0001363829-21-000024 | 10-K | XBRL Viewer

Reinsurance Balances Recoverable on Paid and Unpaid Losses

8. REINSURANCE BALANCES RECOVERABLE ON PAID AND UNPAID LOSSES

The following tables provide the total reinsurance balances recoverable on paid and unpaid losses.


	December 31, 2020
	Non-life Run-off		StarStone		Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	938,231	$	263,638	$	1,201,869
IBNR	508,082		139,761		647,843
ULAE	16,688		—		16,688
Fair value adjustments - acquired companies	(14,014)		(1,339)		(15,353)
Fair value adjustments - fair value option	(21,427)		—		(21,427)
Total reinsurance reserves recoverable	1,427,560		402,060		1,829,620
Paid losses recoverable	172,309		87,234		259,543
Total	$	1,599,869	$	489,294	$	2,089,163

Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable on paid and unpaid losses	$	1,079,039	$	489,294	$	1,568,333
Reinsurance balances recoverable on paid and unpaid losses - fair value option	520,830		—		520,830
Total	$	1,599,869	$	489,294	$	2,089,163


	December 31, 2019
	Non-life Run-off		Atrium		StarStone		Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	972,293	$	9,011	$	264,131	$	1,245,435
IBNR	673,059		19,286		93,185		785,530

Fair value adjustments - acquired companies	(13,652)		519		(2,122)		(15,255)
Fair value adjustments - fair value option	(88,086)		—		—		(88,086)
Total reinsurance reserves recoverable	1,543,614		28,816		355,194		1,927,624
Paid losses recoverable	181,375		1,541		70,594		253,510
Total	$	1,724,989	$	30,357	$	425,788	$	2,181,134

Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable on paid and unpaid losses	$	1,029,471	$	30,357	$	425,788	$	1,485,616
Reinsurance balances recoverable on paid and unpaid losses - fair value option	695,518		—		—		695,518
Total	$	1,724,989	$	30,357	$	425,788	$	2,181,134

Our (re)insurance run-off subsidiaries and assumed portfolios, prior to acquisition, used retrocessional agreements to reduce their exposure to the risk of (re)insurance assumed. On an annual basis, both Atrium (classified as held-for-sale as of December 31, 2020) and StarStone purchased a tailored outwards reinsurance program designed to manage their risk profiles. The majority of Atrium’s and StarStone's third-party reinsurance is with highly rated reinsurers or is collateralized by pledged assets or letters of credit.

The fair value adjustments, determined on acquisition of (re)insurance subsidiaries, are based on the estimated timing of loss and LAE recoveries and an assumed interest rate equivalent to a risk free rate for securities with similar duration to the acquired reinsurance balances recoverable on paid and unpaid losses plus a spread for credit risk, and are amortized over the estimated recovery period, as adjusted for accelerations in timing of payments as a result of commutation settlements. The determination of the fair value adjustments on the retroactive

reinsurance contracts for which we have elected the fair value option is described in Note 12 - "Fair Value Measurements".

As of December 31, 2020 and 2019, we had reinsurance balances recoverable on paid and unpaid losses of $2.1 billion and $2.2 billion, respectively. The decrease of $92.0 million was primarily due to the Hannover Re transaction, cash collections and the classification of Atrium as held-for-sale at December 31, 2020, partially offset by increases due to the retrocession to Enhanzed Re as discussed in Note 21 - "Related Party Transactions"

Top Ten Reinsurers


	December 31, 2020
	Non-life Run-off		StarStone		Total		% of Total
Top 10 reinsurers	$	1,036,676	$	327,917	$	1,364,593	65.3	%
Other reinsurers > $1 million	539,428		158,174		697,602		33.4	%
Other reinsurers < $1 million	23,765		3,203		26,968		1.3	%
Total	$	1,599,869	$	489,294	$	2,089,163	100.0	%


	December 31, 2019
	Non-life Run-off		Atrium		StarStone		Total		% of Total
Top 10 reinsurers	$	1,154,110	$	22,051	$	295,443	$	1,471,604	67.4	%
Other reinsurers > $1 million	551,636		7,761		129,335		688,732		31.6	%
Other reinsurers < $1 million	19,243		545		1,010		20,798		1.0	%
Total	$	1,724,989	$	30,357	$	425,788	$	2,181,134	100.0	%


	December 31, 2020		December 31, 2019
Information regarding top ten reinsurers:
Number of top 10 reinsurers rated A- or better	7		8
Number of top 10 non-rated reinsurers (1)	3		2

Reinsurers rated A- or better in top 10	$	863,819	$	1,199,479
Non-rated reinsurers in top 10 (1)	500,774		272,125
Total top 10 reinsurance recoverables	$	1,364,593	$	1,471,604

Single reinsurers that represent 10% or more of total reinsurance balance recoverables as of December 31, 2020 and 2019:

Hannover Ruck SE (2)	$	—	$	259,077
Lloyd's Syndicates (3)	$	331,118	$	396,246
Michigan Catastrophic Claims Association(4)	$	229,374	$	—

(1) The reinsurance balances recoverable from the three and two non-rated top 10 reinsurers as of December 31, 2020 and 2019, respectively, was comprised of:

•$229.4 million and $190.8 million as of December 31, 2020 and December 31, 2019 respectively, due from a U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state;

•$73.8 million and $81.4 million as of December 31, 2020 and December 31, 2019 respectively, due from a reinsurer who has provided us with security in the form of pledged assets in trust for the full amount of the recoverable balance; and

•$208.4 million as of December 31, 2020 due from Enhanzed Re, an equity method investee to whom some of our subsidiaries have retroceded their exposures through quota share reinsurance agreements as discussed in Note 21 - "Related Party Transactions". These quota share reinsurance agreements are written on a funds withheld basis with our subsidiaries retaining the retrocession premium consideration, to secure the full amount of the recoverable balances due from Enhanzed Re.

(2) Hannover Ruck SE is rated AA- by Standard & Poor’s and A+ by A.M. Best. The transaction described in Note 4 - "Significant New Business" had the effect of reducing the balances due from this reinsurer to below 10% of the total reinsurance balances recoverable as of December 31, 2020.

(3) Lloyd's Syndicates are rated A+ by Standard & Poor's and A by A.M. Best.

(4) U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state.

Allowance for Estimated Uncollectible Reinsurance Balances Recoverable on Paid and Unpaid Losses

We evaluate and monitor the credit risk related to our reinsurers, and an allowance for estimated uncollectible reinsurance balances recoverable on paid and unpaid losses ("allowance for estimated uncollectible reinsurance") is established for amounts considered potentially uncollectible.

With respect to our process for determining the allowances for estimated uncollectible reinsurance, we adopted ASU 2016-13 and the related amendments on January 1, 2020 and recorded a cumulative effect adjustment of $0.2 million to increase the opening retained earnings on the initial adoption of the guidance. Our allowance for estimated uncollectible reinsurance is derived based on various data sources, multiple key inputs and forecast scenarios. These include the duration of the collection period, credit quality, changes in reinsurer credit standing, default rates specific to the individual reinsurer, the geographical location of the reinsurer, contractual disputes with reinsurers over individual contentious claims, contract language or coverage issues, industry analyst reports and consensus economic forecasts.

To determine the allowance for estimated uncollectible reinsurance, we use the PD and LGD methodology whereby each reinsurer is allocated an appropriate PD percentage based on the expected payout duration by portfolio. This PD percentage is then multiplied by an appropriate LGD percentage to arrive at an overall credit allowance percentage which is then applied to the reinsurance balance recoverable for each reinsurer, net of any specific bad debt provisions, collateral or other contract related offsets, to arrive at the overall allowance for estimated uncollectible reinsurance by reinsurer.

The following tables show our gross and net balances recoverable from our reinsurers as well as the related allowance for estimated uncollectible reinsurance broken down by the credit ratings of our reinsurers. The majority of the allowance for estimated uncollectible reinsurance relates to the Non-life Run-off segment.


	December 31, 2020
	Gross		Allowance for estimated uncollectible reinsurance		Net		Provisions as a % of Gross
Reinsurers rated A- or above	$	1,464,529	$	60,801	$	1,403,728	4.2	%
Reinsurers rated below A-, secured	608,999		—		608,999		—	%
Reinsurers rated below A-, unsecured	152,757		76,321		76,436		50.0	%
Total	$	2,226,285	$	137,122	$	2,089,163	6.2	%


	December 31, 2019
	Gross		Allowance for estimated uncollectible reinsurance		Net		Provisions as a % of Gross
Reinsurers rated A- or above	$	1,731,270	$	43,427	$	1,687,843	2.5	%
Reinsurers rated below A-, secured	463,840		—		463,840		—	%
Reinsurers rated below A-, unsecured	133,663		104,212		29,451		78.0	%
Total	$	2,328,773	$	147,639	$	2,181,134	6.3	%

The table below provides a reconciliation of the beginning and ending allowance for estimated uncollectible reinsurance balances for the years ended December 31, 2020 and 2019:


	2020		2019
Allowance for estimated uncollectible reinsurance, beginning of year	$	147,639	$	156,732
Cumulative effect of change in accounting principle	(195)		—
Effect of exchange rate movement	700		(887)
Current period change in the allowance	(381)		2,077
Write-offs charged against the allowance	(9,625)		(9,871)
Recoveries collected	(1,016)		(412)
Allowance for estimated uncollectible reinsurance, end of year	$	137,122	$	147,639

We consider a reinsurance recoverable asset to be past due when it is 90 days past due and record a credit allowance when there is reasonable uncertainty about the collectability of a disputed amount during the reporting period. We did not have significant past due balances older than one year for any of the periods presented.

13. PREMIUMS WRITTEN AND EARNED

The following tables provide a summary of net premiums written and earned for the years ended December 31, 2020, 2019 and 2018:


	2020				2019				2018
	Premiums Written		Premiums Earned		Premiums Written		Premiums Earned		Premiums Written		Premiums Earned
Non-life Run-off
Gross	$	5,191	$	71,522	$	(25,069)	$	197,009	$	(8,910)	$	25,230
Ceded	(2,204)		(12,827)		(269)		(28,513)		(307)		(15,803)
Net	$	2,987	$	58,695	$	(25,338)	$	168,496	$	(9,217)	$	9,427
Atrium
Gross	$	206,656	$	197,492	$	192,373	$	182,678	$	171,494	$	164,428
Ceded	(23,462)		(22,099)		(20,017)		(18,619)		(18,006)		(18,113)
Net	$	183,194	$	175,393	$	172,356	$	164,059	$	153,488	$	146,315
StarStone
Gross	$	326,695	$	441,015	$	472,815	$	549,299	$	622,570	$	647,218
Ceded	(93,493)		(122,900)		(93,292)		(98,187)		(144,561)		(132,055)
Net	$	233,202	$	318,115	$	379,523	$	451,112	$	478,009	$	515,163
Other
Gross	$	13,441	$	19,889	$	18,534	$	20,544	$	32,378	$	25,237
Ceded	—		—		(22)		(164)		(311)		(363)
Net	$	13,441	$	19,889	$	18,512	$	20,380	$	32,067	$	24,874
Total
Gross	$	551,983	$	729,918	$	658,653	$	949,530	$	817,532	$	862,113
Ceded	(119,159)		(157,826)		(113,600)		(145,483)		(163,185)		(166,334)
Net	$	432,824	$	572,092	$	545,053	$	804,047	$	654,347	$	695,779

Gross premiums written for the year ended December 31, 2020 decreased by $106.7 million primarily due to StarStone International being placed into an orderly run-off, whereas gross premiums written for the year ended December 31, 2019 decreased by $158.9 million primarily due to StarStone's strategy to exit certain lines of business.

Deferred Charge Assets and Deferred Gain Liabilities

12 Months Ended

Dec. 31, 2020

Deferred Charge Assets and Deferred Gain Liabilities

9. DEFERRED CHARGE ASSETS AND DEFERRED GAIN LIABILITIES

Deferred charge assets and deferred gain liabilities relate to retroactive reinsurance policies providing indemnification of losses and LAE with respect to past loss events in the Non-life Run-off segment. For (re)insurance contracts for which we do not elect the fair value option, a deferred charge asset is recorded for the excess, if any, of the estimated ultimate losses payable over the premiums received at the initial measurement; whereas, a deferred gain liability is recorded for the excess, if any, of the premiums received over the estimated ultimate losses payable at the initial measurement. In addition, for retrocessions of losses and LAE reserves that we have assumed through retroactive reinsurance contracts where the retroceded liabilities exceed the retrocession premiums paid, we record the excess as a deferred gain liability which is amortized to earnings over the estimated period during which the losses paid on the assumed retroceded liabilities are recovered from the retrocessionaire. For further information on our deferred charge assets and deferred gain liabilities, refer to Note 2 - "Significant Accounting Policies."

Deferred Charge Assets

Deferred charge assets are included in other assets on our consolidated balance sheets. The following table presents a reconciliation of the deferred charge assets for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Beginning carrying value	$	272,462	$	86,585	$	80,192
Recorded during the year	11,746		224,504		20,174
Amortization	(45,606)		(38,627)		(13,781)

Ending carrying value	$	238,602	$	272,462	$	86,585

Deferred charge assets are assessed at each reporting period for impairment. If the asset is determined to be impaired, it is written down in the period in which the determination is made. For the year ended December 31, 2020, we completed our assessment for impairment of deferred charge assets and concluded that there had been no impairment of our carried deferred charge asset balances.

Further information on deferred charges recorded during the years ended December 31, 2020, 2019 and 2018 is included in Note 4 - "Significant New Business."

Deferred Gain Liabilities

Deferred gain liabilities are included in other liabilities on our consolidated balance sheets. The following table presents a reconciliation of the deferred gain liabilities for the years ended December 31, 2020 and 2019:


	2020		2019
Beginning carrying value	$	12,875	$	—
Recorded during the year	9,365		13,758
Amortization	(2,360)		(883)

Ending carrying value	$	19,880	$	12,875

Losses and Loss Adjustment Expenses

12 Months Ended

Dec. 31, 2020

Losses and Loss Adjustment Expenses

10. LOSSES AND LOSS ADJUSTMENT EXPENSES

The liability for losses and loss adjustment expenses ("LAE"), also referred to as loss reserves, represents our gross estimates before reinsurance for unpaid reported losses and includes losses that have been incurred but not reported ("IBNR") for our Non-life Run-off, Atrium (classified as held-for-sale as of December 31, 2020) and StarStone segments using a variety of actuarial methods. We recognize an asset for the portion of the liability that we expect to recover from reinsurers. LAE reserves include allocated loss adjustment expenses ("ALAE"), and unallocated loss adjustment expenses ("ULAE"). ALAE are linked to the settlement of an individual claim or loss, whereas ULAE are based on our estimates of future costs to administer the claims. IBNR represents reserves for loss and LAE that have been incurred but not yet reported to us. This includes amounts for unreported claims, development on known claims and reopened claims.

Our loss reserves cover multiple lines of business, including asbestos, environmental, general casualty, workers' compensation/personal accident, marine, aviation and transit, construction defect, professional indemnity/directors and officers, motor, property and other non-life lines of business.

The following tables summarize the liability for losses and LAE by segment and for our other activities.


	2020
	Non-life Run-off		StarStone		Other		Total
Outstanding losses	$	4,440,425	$	677,220	$	10,204	$	5,127,849
IBNR	4,641,500		615,963		20,040		5,277,503
Fair value adjustments - acquired companies	(142,854)		(329)		—		(143,183)
Fair value adjustments - fair value option	(54,589)		—		—		(54,589)
ULAE	350,600		35,102		—		385,702
Total	$	9,235,082	$	1,327,956	$	30,244	$	10,593,282

Reconciliation to Consolidated Balance Sheet:
Loss and loss adjustment expenses	$	6,782,162	$	1,327,956	$	30,244	$	8,140,362
Loss and loss adjustment expenses, at fair value	2,452,920		—		—		2,452,920
Total	$	9,235,082	$	1,327,956	$	30,244	$	10,593,282


	2019
	Non-life Run-off		Atrium		StarStone		Other		Total
Outstanding losses	$	4,407,082	$	89,141	$	743,830	$	9,512	$	5,249,565
IBNR	3,945,407		136,543		556,134		13,565		4,651,649
Fair value adjustments- acquired companies	(170,689)		3,700		(522)		—		(167,511)
Fair value adjustments - fair value option	(217,933)		—		—		—		(217,933)
ULAE	331,494		2,288		18,852		—		352,634
Total	$	8,295,361	$	231,672	$	1,318,294	$	23,077	$	9,868,404

Reconciliation to Consolidated Balance Sheet:
Loss and loss adjustment expenses	$	5,674,239	$	231,672	$	1,318,294	$	23,077	$	7,247,282
Loss and loss adjustment expenses, at fair value	2,621,122		—		—		—		2,621,122
Total	$	8,295,361	$	231,672	$	1,318,294	$	23,077	$	9,868,404

The overall increase in the liability for losses and LAE between December 31, 2019 and December 31, 2020 was primarily attributable to the reinsurance transactions completed in 2020, as described in Note 4 - "Significant New Business," net incurred losses and LAE and foreign exchange losses in the year, partially offset by losses paid in the year.

The table below provides a consolidated reconciliation of the beginning and ending liability for losses and LAE.


	2020		2019		2018
Balance as of January 1	$	9,868,404	$	9,048,796	$	7,100,488
Less: reinsurance reserves recoverable	1,927,624		1,708,272		1,693,028
Less: net deferred charge assets and gain liabilities on retroactive reinsurance	259,587		86,585		80,192

Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances (1)	643		—		—
Net balance as of January 1	7,680,550		7,253,939		5,327,268
Net incurred losses and LAE:
Current period	405,178		580,074		533,081
Prior periods	10,748		34,105		(209,359)
Total net incurred losses and LAE	415,926		614,179		323,722
Net paid losses:
Current period	(71,989)		(179,461)		(176,172)
Prior periods	(1,413,500)		(1,609,009)		(1,158,614)
Total net paid losses	(1,485,489)		(1,788,470)		(1,334,786)
Effect of exchange rate movement	119,663		47,812		(145,243)
Acquired on purchase of subsidiaries	—		686		1,310,874
Assumed business	2,186,024		1,586,307		1,772,104
Ceded business	(154,926)		(33,260)		—
Reclassification to assets and liabilities held-for-sale	(216,808)		—		—
Net balance as of December 31	8,544,940		7,681,193		7,253,939
Plus: reinsurance reserves recoverable (2)	1,829,620		1,927,624		1,708,272
Plus: net deferred charge assets and gain liabilities on retroactive reinsurance	218,722		259,587		86,585
Balance as of December 31	$	10,593,282	$	9,868,404	$	9,048,796

(1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details. This amount excludes $0.4 million related to the adoption impact of ASU 2016-13 on StarStone U.S., which has been classified as a discontinued operation with the related assets and liabilities disclosed as held-for-sale on our consolidated balance sheets.

(2) Net of allowance for estimated uncollectible reinsurance.

The tables below provide the components of net incurred losses and LAE by segment and for our other activities.


	2020
	Non-life Run-off		Atrium		StarStone		Other		Total
Net losses paid	$	1,074,901	$	73,920	$	326,868	$	9,800	$	1,485,489
Net change in case and LAE reserves (1)	(453,080)		7,245		(95,044)		692		(540,187)
Net change in IBNR reserves (2)	(718,414)		6,661		17,654		6,475		(687,624)
Increase (reduction) in estimates of net ultimate losses	(96,593)		87,826		249,478		16,967		257,678

Increase (reduction) in provisions for unallocated LAE (3)	(48,765)		(29)		17,244		—		(31,550)
Amortization of deferred charge assets and deferred gain liabilities (4)	42,640		—		606		—		43,246
Amortization of fair value adjustments (5)	28,667		(571)		(590)		—		27,506
Changes in fair value - fair value option (6)	119,046		—		—		—		119,046
Net incurred losses and LAE	$	44,995	$	87,226	$	266,738	$	16,967	$	415,926


	2019
	Non-life Run-off		Atrium		StarStone		Other		Total
Net losses paid	$	1,247,624	$	78,189	$	450,835	$	11,822	$	1,788,470
Net change in case and LAE reserves (1)	(530,891)		3,534		(4,686)		3,460		(528,583)
Net change in IBNR reserves (2)	(812,699)		(4,782)		22,021		756		(794,704)
Increase (reduction) in estimates of net ultimate losses	(95,966)		76,941		468,170		16,038		465,183

Increase (reduction) in provisions for unallocated LAE (3)	(57,404)		—		902		—		(56,502)
Amortization of deferred charge assets and deferred gain liabilities (4)	37,744		—		—		—		37,744
Amortization of fair value adjustments (5)	50,070		335		168		—		50,573
Changes in fair value - fair value option (6)	117,181		—		—		—		117,181
Net incurred losses and LAE	$	51,625	$	77,276	$	469,240	$	16,038	$	614,179


	2018
	Non-life Run-off		Atrium		StarStone		Other		Total
Net losses paid	$	838,817	$	64,506	$	427,371	$	4,092	$	1,334,786
Net change in case and LAE reserves (1)	(547,420)		6,331		63,861		4,808		(472,420)
Net change in IBNR reserves (2)	(565,385)		4,091		46,501		7,999		(506,794)
Increase (reduction) in estimates of net ultimate losses	(273,988)		74,928		537,733		16,899		355,572

Increase (reduction) in provisions for unallocated LAE (3)	(65,401)		—		5,613		—		(59,788)
Amortization of deferred charge assets and deferred gain liabilities (4)	13,781		—		—		—		13,781
Amortization of fair value adjustments (5)	12,877		(5,118)		(266)		—		7,493
Changes in fair value - fair value option (6)	6,664		—		—		—		6,664
Net incurred losses and LAE	$	(306,067)	$	69,810	$	543,080	$	16,899	$	323,722

(1)Comprises the movement during the year in specific case reserve liabilities as a result of claims settlements or changes advised to us by our policyholders and attorneys, less changes in case reserves recoverable advised by us to our reinsurers as a result of the settlement or movement of assumed claims.

(2)Represents the gross change in our actuarial estimates of IBNR, less amounts recoverable.

(3) Represents the change in the estimate of the total future costs to administer the claims.

(4) Relates to the amortization of deferred charge assets and deferred gain liabilities on retroactive reinsurance contracts.

(5) Relates to the amortization of fair value adjustments associated with the acquisition of companies. .

(6) Represents the changes in the fair value of liabilities related to our assumed retroactive reinsurance agreements for which we have elected the fair value option.

Loss Development Information

Methodology for Establishing Reserves

The liability for losses and LAE includes an amount determined from reported claims and an amount based on historical loss experience and industry statistics for IBNR using a variety of actuarial methods. Our loss reserves cover multiple lines of business, including workers' compensation, general casualty, asbestos and environmental, marine, aviation and transit, construction defects and other non-life lines of business. Our management, through our loss reserving committees, considers the reasonableness of loss reserves recommended by our actuaries, including actual loss development during the year.

Case reserves are recognized for known claims (including the cost of related litigation) when sufficient information has been reported to us to indicate the involvement of a specific insurance policy. We use considerable judgment in estimating losses for reported claims on an individual claim basis based upon our knowledge of the circumstances surrounding the claim, the severity of the injury or damage, the jurisdiction of the occurrence, the potential for ultimate exposure, the type of loss, and our experience with the line of business and policy provisions relating to the particular type of claim. The reserves for unpaid reported losses and LAE are established by management based on reports from brokers, ceding companies and insureds and represent the estimated ultimate cost of events or conditions that have been reported to, or specifically identified, by us. We also consider facts currently known and the current state of the law and coverage litigation.

IBNR reserves are established by management based on actuarially determined estimates of ultimate losses and loss expenses. We use generally accepted actuarial methodologies to estimate ultimate losses and LAE and those estimates are reviewed by management. In addition, the routine settlement of claims, at either below or above the carried advised loss reserve, updates historical loss development information to which actuarial methodologies are applied, often resulting in revised estimates of ultimate liabilities. On an annual basis, independent actuarial firms are retained by management to provide their estimates of ultimate losses and to review the estimates developed by our actuaries.

Within the annual loss reserve studies produced by either our actuaries or independent actuaries, exposures for each subsidiary are separated into homogeneous reserving categories for the purpose of estimating IBNR. Each reserving category contains either direct insurance or assumed reinsurance reserves and groups relatively similar types of risks and exposures (for example, asbestos, environmental, casualty, property) and lines of business written (for example, marine, aviation, non-marine). Based on the exposure characteristics and the nature of available data for each individual reserving category, a number of methodologies are applied. Recorded reserves for each category are selected from the actuarial indications produced by the various methodologies after consideration of exposure characteristics, data limitations and strengths and weaknesses of each method applied. This approach to estimating IBNR has been consistently adopted in the annual loss reserve studies for each period presented.

The estimation of unpaid claim liabilities at any given point in time is subject to a high degree of uncertainty for a number of reasons. A significant amount of time can lapse between the assumption of risk, the occurrence of a loss event, the reporting of the event to an insurance or reinsurance company and the ultimate payment of the claim on the loss event. Our actuarial methodologies include amongst other methodologies industry benchmarking which, under certain actuarial methods, compares the trend of our loss development to that of the industry. To the extent that the trend of our loss development compared to the industry changes in any period, it is likely to have an impact on our estimate of ultimate liabilities. Unpaid claim liabilities for property and casualty exposures in general are impacted by changes in the legal environment, jury awards, medical cost trends and general inflation. Certain estimates for unpaid claim liabilities involve considerable uncertainty due to significant coverage litigation, and it can be unclear whether past claim experience will be representative of future claim experience. Ultimate values for such claims cannot be estimated using reserving techniques that extrapolate losses to an ultimate basis using loss development factors, and the uncertainties surrounding the estimation of unpaid claim liabilities are not likely to be resolved in the near future. In addition, reserves are established to cover loss development related to both known and unasserted claims. Consequently, our subsequent estimates of ultimate losses and LAE, and our liability for losses and LAE, may differ materially from the amounts recorded in our consolidated financial statements.

These estimates are reviewed regularly and, as experience develops and new information becomes known, the reserves are adjusted as necessary. Such adjustments (i.e. change in ultimate losses), if any, will be recorded in earnings in the period in which they become known. Prior period development arises from changes to loss estimates recognized in the current year that relate to loss reserves established in previous calendar years.

Asbestos and Environmental

In establishing the reserves for losses and LAE related to asbestos and environmental claims, management considers facts currently known and the current state of the law and coverage litigation environment. Liabilities are recognized for known claims (including the cost of related litigation) when sufficient information has been developed to indicate the involvement of a specific insurance policy, and management can reasonably estimate its liability. In addition, reserves have been established to cover additional exposures on both known and unreported claims. Estimates of the reserves are reviewed and updated continually. Developed case law and claim histories are still evolving for such claims, especially because significant uncertainty exists about the outcome of coverage litigation and whether past claim experience will be representative of future claim experience. In view of the changes in the legal and tort environment that affect the development of such claims, the uncertainties inherent in valuing asbestos and environmental claims are not likely to be resolved in the near future. Ultimate values for such claims cannot be estimated using traditional reserving techniques and there are significant uncertainties in estimating the amount of our potential losses for these claims. There can be no assurance that the reserves established by us will be adequate or will not be adversely affected by the development of other latent exposures.

The net liability for unpaid losses and LAE as of December 31, 2020 and 2019 included $1.9 billion and $2.1 billion, respectively, which represented an estimate of the net ultimate liability for asbestos and environmental claims. The gross liability for such claims as of December 31, 2020 and 2019 was $2.1 billion and $2.3 billion, respectively. For the years ended December 31, 2020 and 2019, our reserves for asbestos and environmental liabilities decreased by $178.2 million and increased by $419.9 million on a gross basis, respectively, and decreased by $227.2 million and increased by $374.7 million on a net basis, respectively. The decrease in 2020 was primarily due to net paid losses while the increase in 2019 was primarily due to acquisition activity, partially offset by net paid losses.

Disclosures of Incurred and Paid Loss Development, IBNR, Claims Counts and Payout Percentages

The loss development tables disclosed below, sets forth our historic incurred and paid loss development by accident year through December 31, 2020, net of reinsurance, as well as the cumulative number of reported claims, IBNR balances, and other supplementary information.

The loss development tables disclosed below are presented as follows:

•Non-Life Run-off - Loss development disclosures have been provided for the 10 latest acquisition years, in addition to disclosures for lines of business with material net losses and LAE reserve balances as of December 31, 2020, within those 10 latest acquisition years, also being provided. The disaggregated lines of business include general casualty, workers’ compensation, motor and professional indemnity and directors and officers.

•StarStone - All the lines of business related to the StarStone segment have been included within the loss development disclosures below, namely, casualty, marine, property, aerospace and workers’ compensation.

Incurred and Paid Loss Development and IBNR Disclosures

For each acquisition year and/or line of business for which incurred losses and allocated loss adjustment expenses, net of reinsurance tables have been provided below, the disclosure approach and format adopted reflects the following:

•The incurred loss development tables include both reported case reserves and IBNR liabilities, as well as cumulative paid losses;

•Both the incurred and cumulative paid loss development tables include allocated LAE (i.e. claims handling costs allocated to specific individual claims) but exclude unallocated LAE (i.e. the costs associated with internal claims staff and third party administrators as well as consultants that cannot be allocated to specific individual claims);

•The fair value adjustments related to business acquisitions are excluded from the loss development tables, however the undiscounted incurred losses, cumulative paid losses and allocated LAE related to business acquisitions are included in the loss development tables;

•The fair value adjustments related to retroactive reinsurance agreements for which we have elected the fair value option are excluded from the loss development tables, however the undiscounted incurred losses, cumulative paid losses and allocated LAE related to retroactive reinsurance agreements for which we have elected the fair value option are included in the loss development tables;

•The amounts relating to the amortization of deferred charge assets and deferred gain liabilities are excluded from the loss development tables;

•In the incurred loss development tables, the incurred effect of agreeing a commutation or policy buyback is included in the period in which the commutation or policy buyback is contractually agreed. We reflect the net incurred loss development arising from a commutation or policy buyback in the fiscal year in which a commutation or policy buyback is contractually agreed, and the net incurred loss development is allocated to the appropriate accident year. The claim will generally have been adjusted throughout its lifetime and the amounts recorded in prior years (which is considered supplementary information) remain unchanged in our loss development tables, such that the incurred amount that we recognize in the year in which a commutation or policy buyback is contractually agreed represents the effect of the commutation or policy buyback settlement compared to the carried net loss and LAE reserve balance in the prior year. We do not recast prior years to remove commuted or bought back claims, since this practice would eliminate any historical favorable or adverse development we may have experienced on the commuted loss and LAE reserves. Reserves that have been commuted or bought back are not adjusted in future years but the commuted or bought back value remains in our total incurred losses;

•In the cumulative paid losses tables, we reflect the amount of the commutation or policy buyback settlements in the year in which they are actually paid or received, and the net payment is allocated to the appropriate accident year. The claim or recoverable may have recorded payments or receipts throughout its lifetime and amounts recorded in prior years (which is considered supplementary information) remain unchanged in our loss development tables, such that the amounts paid or received that we recognize in the year in which a commutation or policy buyback is paid or received represents the amount actually paid or received. We do not recast prior years to remove payments or receipts related to commutations or policy buybacks, since we consider commutations and policy buybacks a key component of our business and are reflective of our ability to effectively manage acquired losses and LAE liabilities. Payments relating to commutations and policy buybacks are not adjusted in future years but the payments remain in our total cumulative paid losses;

•The amounts included within the loss development tables for the years ended December 31, 2011 through to December 31, 2019 (and in the case of StarStone, from April 1, 2014 its acquisition date through to December 31, 2019), as well as the historical average annual percentage payout ratios as of December 31, 2020, are presented as supplementary information and are therefore unaudited;

•All data presented within the loss development tables is net of reinsurance recoveries, excluding provisions for uncollectible reinsurance recoverables;

•All the incurred and paid loss activity presented within the loss development tables provided below, exclude intercompany cessions. Upon the sale of StarStone U.S. to Core Specialty on November 30, 2020, the incurred and paid loss development activity related to the cessions from StarStone U.S. to our other subsidiaries were no longer eliminated on consolidation and have been included within the loss development tables presented below;

•The IBNR reserves included within each incurred loss development table by accident year, reflect the net IBNR recorded as of December 31, 2020, including expected development on reported losses;

•For the Non-life Run-off segment loss development tables, all information for both acquisitions and retroactive reinsurance agreements is presented prospectively. As the loss reserves are effectively re-underwritten at the date that they are acquired or assumed, we believe that the historical loss development prior to their acquisition is not relevant with respect to our own experience managing these acquired loss reserves. In addition, the information required to prepare the loss development disclosures on a retrospective basis is not always available to us and a mixed presentation approach would result in loss development tables that are not entirely reflective of the actual loss development of the acquired loss reserves;

•For the Non-life Run-off segment we have also presented the net incurred and paid losses and ALAE information by calendar year as well as IBNR and claim counts for accident years older than 10 years on a single row within the loss development tables. This presentation differs from the typical approach where only the net outstanding losses and LAE reserves are presented as a reconciling item at the bottom of the loss development tables. The additional detailed disclosures are provided on a voluntary basis and the inclusion of the disclosures is to provide additional information to the users of our financial statements and to also enable the reconciliation of our total loss reserves by acquisition year and by significant line of business;

•For the StarStone segment loss development tables, all information has been presented on a prospective basis from the date of our acquisition of StarStone, which was effective on April 1, 2014. Providing pre-acquisition incurred and paid losses by accident year for years prior to 2014 was determined to be impracticable due to significant data limitations; and

•Following our sale of StarStone U.S. to Core Specialty which was completed on November 30, 2020, the loss development disclosures presented below for all the individual lines of business within the StarStone segment have been restated to exclude the historical incurred and paid loss development related to StarStone U.S.

The historical amounts disclosed within the loss development tables for all the acquisition years and lines of business presented below are on a constant-currency basis, which is achieved by using constant foreign exchange rates between periods in the loss development tables, and translating prior period amounts denominated in currencies other than the U.S. dollar, which is our reporting currency, using the closing exchange rates as of December 31, 2020.

The impact of this exchange rate conversion is to show the change between periods exclusive of the effect of exchange rate fluctuations, which would otherwise distort the change in incurred losses and the cash flow patterns associated with those incurred losses shown within the loss development tables. The change in net incurred losses shown within the loss development tables will, however, differ from other U.S. GAAP disclosures of incurred current and prior period reserve development amounts, which include the effect of exchange rate fluctuations.

Establishing an estimate for loss reserves involves various assumptions and judgments, therefore, the information contained within the loss development disclosures only allows readers or users of our consolidated financial statements to understand, at the summary level presented in the development tables, the change over time in our reported incurred loss estimates as well as the nature and patterns of the cash flows associated with those estimates. We, therefore, believe that the information provided within the loss development tables disclosed below is of limited use for independent analysis or application of standard actuarial estimations, and any results obtained from doing so should be interpreted with caution.

Cumulative Number of Reported Claims

Reported claim counts, on a cumulative basis, are provided as supplemental information to each incurred loss development table by accident year. We measure claim frequency information on an individual claim count basis within each of our segments as follows:

•Non-Life Run-off - The claim frequency information for the exposures included within our Non-life Run-off lines of business includes direct and assumed open and closed claims by accident year at the claimant level. Reported claims that are closed without a payment are included within our cumulative number of reported claims because we typically incur claim adjustment expenses on them prior to their closure. The claim count numbers exclude counts related to claims within policy deductibles where the insured is responsible for the payment of losses within the deductible layer. Individual claim counts related to certain assumed reinsurance contracts such as excess-of-loss and quota share treaties are not available to us, and the losses arising from these treaties have been treated as single claims for the purposes of determining

claim counts. Therefore, each treaty year within the reinsurance contract is deemed a single claim because the detailed underlying individual claim information is generally not reported to us by our cedants; and

•StarStone - The claim frequency information is determined at the claimant level for the exposures within the lines of business related to these segments. Our claims system assigns a unique claim identifier to each reported claim we receive. Each unique claim identifier is deemed to be a single claim, irrespective of whether the claim remains open or has been closed with or without payment. For certain insurance facilities and business produced or managed by managing general agents, coverholders and third party administrators where the underlying claims data is reported to us in an aggregated format, the information necessary to provide cumulative claims frequency is not available. In such cases, we typically record a “block” claim in our system. This also applies to a small amount of assumed reinsurance business that we write where, similarly, the underlying claims data is reported to us in an aggregated format. In such instances, each assumed reinsurance contract is deemed a single claim.

Our reported claim frequency information is subject to the following inherent limitations when analyzing our loss experience and severity:

•Claim counts are presented only on a reported and not on an ultimate basis. Therefore, reported claim counts include open claims which have outstanding reserves but exclude IBNR claims. As such the reported claims are consistent with reported losses, which can be calculated by subtracting IBNR losses from incurred losses. However, the reported claim counts are inconsistent with the losses in the incurred loss development tables, which include IBNR losses, and to losses in the paid loss development tables, which exclude outstanding reserves;

•Reported claim counts have not been adjusted for ceded reinsurance, which may distort any measures of frequency or severity;

•For lines of business that have a mix of primary and excess layer exposures, such as our general casualty and workers’ compensation lines of business, the reported claim counts may fluctuate from period to period between exposure layers, thereby distorting any measure of frequency and severity; and

•The use of our reported claim frequency information to project ultimate loss payouts by disaggregated disclosure category or line of business may not be as meaningful as claim count information related to individual contracts at a more granular level.

Payout Percentages

•Non-life Run-off - The annual percentage payout disclosures for our Non-life Run-off segment are based on the payout of incurred claims by age, net of reinsurance. For our Non-life Run-off segment, claims aging reflects the number of years that have lapsed since the original acquisition of the related net liability for losses and LAE reserves to the date the claim is paid. There may be occasions where, due to our claims management strategies (including commutations and policy buy-backs) or due to the timing of claims payments relative to the associated recovery, the cash received from reinsurance recoveries is greater than the cash paid out to our claimants, (i.e. a net recovery rather than a net payout for a particular calendar year), thereby resulting in a negative annual percentage payout for that calendar year.

•StarStone - The average annual percentage payout disclosures for our StarStone segment are based on the payout of incurred claims by age, net of reinsurance.

Non-Life Run-off Segment

The table below provides a reconciliation of the beginning and ending reserves for losses and LAE for the Non-life Run-off segment.


	2020		2019		2018
Balance as of January 1	$	8,295,361	$	7,540,662	$	5,949,472
Less: reinsurance reserves recoverable	1,543,614		1,366,123		1,377,485
Less: net deferred charge assets and gain liabilities on retroactive reinsurance	259,587		86,585		80,192
Plus: cumulative effect of change in accounting principal on allowance for estimated uncollectible reinsurance (1)	703		—		—
Net balance as of January 1	6,492,863		6,087,954		4,491,795
Net incurred losses and LAE:
Current period	30,165		123,559		12,451
Prior periods	14,830		(71,934)		(318,518)
Total net incurred losses and LAE	44,995		51,625		(306,067)
Net paid losses:
Current period	(9,990)		(64,820)		(5)
Prior periods	(1,064,911)		(1,182,804)		(838,812)
Total net paid losses	(1,074,901)		(1,247,624)		(838,817)
Effect of exchange rate movement	94,745		46,472		(132,632)
Acquired on purchase of subsidiaries	—		686		1,111,839
Assumed business	2,186,024		1,586,307		1,761,836
Ceded business	(154,926)		(33,260)		—
Net balance as of December 31	7,588,800		6,492,160		6,087,954
Plus: reinsurance reserves recoverable(2)	1,427,560		1,543,614		1,366,123
Plus: net deferred charge assets and gain liabilities on retroactive reinsurance	218,722		259,587		86,585
Balance as of December 31	$	9,235,082	$	8,295,361	$	7,540,662

(1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details.

(2) Net of allowance for estimated uncollectible reinsurance.

Net incurred losses and LAE in the Non-life Run-off segment were as follows:


	2020						2019						2018
	Prior Period		Current Period		Total		Prior Period		Current Period		Total		Prior Period		Current Period		Total
Net losses paid	$	1,064,911	$	9,990	$	1,074,901	$	1,182,804	$	64,820	$	1,247,624	$	838,812	$	5	$	838,817
Net change in case and LAE reserves (1)	(449,610)		(3,470)		(453,080)		(553,996)		23,105		(530,891)		(552,124)		4,704		(547,420)
Net change in IBNR reserves (2)	(742,417)		24,003		(718,414)		(847,893)		35,194		(812,699)		(573,127)		7,742		(565,385)
Increase (reduction) in estimates of net ultimate losses	(127,116)		30,523		(96,593)		(219,085)		123,119		(95,966)		(286,439)		12,451		(273,988)

Increase (reduction) in provisions for unallocated LAE (3)	(48,407)		(358)		(48,765)		(57,844)		440		(57,404)		(65,401)		—		(65,401)
Amortization of deferred charge assets and deferred gain liabilities (4)	42,640		—		42,640		37,744		—		37,744		13,781		—		13,781
Amortization of fair value adjustments (5)	28,667		—		28,667		50,070		—		50,070		12,877		—		12,877
Changes in fair value - fair value option (6)	119,046		—		119,046		117,181		—		117,181		6,664		—		6,664
Net incurred losses and LAE	$	14,830	$	30,165	$	44,995	$	(71,934)	$	123,559	$	51,625	$	(318,518)	$	12,451	$	(306,067)

(2)Represents the gross change in our actuarial estimates of IBNR, less amounts recoverable.

(3) Represents the change in the estimate of the total future costs to administer the claims.

(4) Relates to the amortization of deferred charge assets and deferred gain liabilities on retroactive reinsurance contracts.

(5) Relates to the amortization of fair value adjustments associated with the acquisition of companies.

(6) Represents the changes in the fair value of liabilities related to our assumed retroactive reinsurance agreements for which we have elected the fair value option.

Year Ended December 31, 2020

The following table shows the components of the 2020 reduction in estimates of net ultimate losses related to prior periods by line of business for the Non-life Run-off segment.


	2020
	Net losses paid		Net change in case and LAE reserves		Net change in IBNR reserves		Increase (reduction) in estimates of net ultimate losses
Asbestos	$	132,853	$	(1,300)	$	(150,054)	$	(18,501)
Environmental	23,866		(266)		(36,362)		(12,762)
General Casualty	170,502		(68,744)		(127,421)		(25,663)
Workers' Compensation	142,790		(176,927)		(149,198)		(183,335)
Marine, aviation and transit	33,927		(14,458)		(50,558)		(31,089)
Construction defect	27,476		(6,092)		(13,382)		8,002
Professional indemnity/ Directors & Officers	63,878		3,698		(79,181)		(11,605)
Motor	349,366		(106,561)		(95,040)		147,765
Property	71,422		(24,356)		(64,331)		(17,265)
All Other	48,831		(54,604)		23,110		17,337
Total	$	1,064,911	$	(449,610)	$	(742,417)	$	(127,116)

The significant drivers of the 2020 reduction in estimates of net ultimate losses are explained below.

Workers' Compensation - The workers’ compensation line of business experienced a $183.3 million reduction in estimates of net ultimate losses as a result of favorable actual development versus expected development across

nearly all our acquired companies and assumed portfolios. We continue to drive favorable loss experience by proactively settling claims for less than the current case reserves. During 2020, we paid net losses of $142.8 million and released case and LAE reserves of $176.9 million. This represents a decline in reported losses of $34.1 million for the year. As a result of the favorable development in our data, our actuarial analyses indicated and resulted in a release of $149.2 million of IBNR reserves, primarily attributed to a settlement of an outwards reinsurance agreement resulting in the reduction in gross ultimate losses inuring to our benefit.

We also continue to actively seek to commute policies in our workers' compensation line of business when possible, and where the commutation of the policy is settled at a level below the carried value of the loss reserves, we record a reduction in our estimates of net ultimate losses. Included in the net paid losses and released case and LAE reserves were 10 commutations that resulted in a net reduction of ultimate losses of $10.8 million.

Marine, aviation and transit - We experienced $31.1 million of favorable development in our marine, aviation and transit line of business. The reduction in net ultimate loss reserves was driven by a number of favorable outcomes on certain large claims from our London based portfolios and better actual than expected experience of reported losses across most reserve segments which led to releases of IBNR reserves as a result of our annual actuarial analyses.

General casualty - Our general casualty line of business experienced $25.7 million in favorable loss development which was the result of better actual than expected claim emergence across several portfolios including a new portfolio acquired in 2020 that underwent its first actuarial analysis by our outside actuarial consultant. To date, we have not experienced adverse social inflation in our general casualty line of business since we are generally proactive in settling claims early for fair value which reduces legal costs for both the defendant and plaintiff.

Motor - The experience in the motor line was adverse by $147.8 million due to higher than expected severity related to a recent assumed loss portfolio transfer transaction. The case reserves were significantly strengthened when we transferred the claim handling to a new third-party administrator with specialist experience in commercial automobile exposures. Along with the new third-party administrator, we have implemented several claim initiatives aimed at reducing defense costs, settling claims earlier, lowering claims severity and increased governance and technical oversight.

Other significant components of the 2020 net incurred losses and LAE include losses related to 2020 net earned premium of $30.2 million, an increase in the fair value of liabilities of $119.0 million related to our assumed retroactive reinsurance agreements for which we have elected the fair value option, primarily due to narrowing credit spreads on corporate bond yields in 2020 and 15 commutations in lines other than workers’ compensation resulting in a decrease of $12.3 million.

Year Ended December 31, 2019

The following table shows the components of the 2019 reduction in estimates of net ultimate losses related to prior periods by line of business for the Non-life Run-off segment.


	2019
	Net losses paid		Net change in case and LAE reserves		Net change in IBNR reserves		Increase (reduction) in estimates of net ultimate losses
Asbestos	$	118,557	$	35,003	$	(146,749)	$	6,811
Environmental	16,899		13,796		(15,707)		14,988
General Casualty	175,044		(89,968)		(91,818)		(6,742)
Workers' Compensation	208,961		(156,435)		(188,944)		(136,418)
Marine, aviation and transit	82,058		(77,958)		(24,508)		(20,408)
Construction defect	32,078		(8,313)		(25,025)		(1,260)
Professional indemnity/ Directors & Officers	103,413		(36,986)		(104,984)		(38,557)
Motor	276,563		(134,127)		(179,887)		(37,451)
Property	94,093		(73,259)		(7,358)		13,476
All Other	75,138		(25,749)		(62,913)		(13,524)
Total	$	1,182,804	$	(553,996)	$	(847,893)	$	(219,085)

The significant drivers of the 2019 reduction in estimates of net ultimate losses are explained below.

Workers' Compensation - A $136.4 million reduction in estimates of net ultimate losses in our workers' compensation line of business arose across multiple portfolios, where reported loss development was generally significantly less than expected development. The lower than expected actual development was driven by significant proactive settlement activity on individual claimants where we were able to settle claims lower than the case reserve estimates. For example, in two of our portfolios we observed favorable reported loss development, where we paid $39.3 million in loss payments to release a corresponding $53.6 million of associated case reserves for $14.3 million in favorable reported loss development. These settlement activities and the favorable actual loss development versus expected loss development, led to a change in the actuarial assumptions in the annual reserve study that reflect this favorable loss development.

We also continue to actively seek to commute policies in our workers' compensation line of business when possible, and where the commutation of the policy is settled at a level below the carried value of the loss reserves, we record a reduction in our estimates of net ultimate losses. During 2019, we completed 6 commutations across several workers' compensation portfolios that contributed to a $6.1 million reduction in estimates of net ultimate losses.

Professional Indemnity/Directors & Officers - A $38.6 million reduction in estimates of net ultimate losses in our professional indemnity/directors’ & officers’ line of business arose based on the annual actuarial analysis which reflected the better than expected loss development during 2019. As part of the reserve analysis, an in-depth review of recently acquired portfolios’ ceded reinsurance programs led to an increase in the ceded reinsurance asset of $13.5 million, which is a reduction in net ultimate losses.

Asbestos - A $6.8 million increase in estimates of net ultimate losses in our asbestos line of business arose primarily due to changes in our actuarial assumptions related to dismissal rates. During 2019, the number of new defendants and filed claims was less than expected, but this was offset by a lowering of the dismissal rate. In asbestos, the dismissal rates are extremely high as many of the claims do not have merit against the insured. However, we have seen a trend in both US and UK exposure of the dismissal rate decreasing in the range of 2 to 3 percentage points.

Similar to workers’ compensation business, during 2019, we completed 6 commutations across several portfolios that contributed to a $9.8 million reduction in estimates of net ultimate losses.

Other - All other line of business changes in estimates of net ultimate losses were primarily due to the application of our reserving methodologies, favorable actual versus expected loss development and proactive claim management.

Other significant components of the 2019 net incurred losses and LAE include losses related to 2019 net earned premium of $123.6 million and an increase in the fair value of liabilities of $117.2 million related to our assumed retroactive reinsurance agreements for which we have elected the fair value option, primarily due to narrowing credit spreads on corporate bond yields in 2019.

Year Ended December 31, 2018

The following table shows the components of the 2018 reduction in estimates of net ultimate losses related to prior periods by line of business for the Non-life Run-off segment.


	2018
	Net losses paid		Net change in case and LAE reserves		Net change in IBNR reserves		Increase (reduction) in estimates of net ultimate losses
Asbestos	$	108,248	$	(21,535)	$	(151,662)	$	(64,949)
Environmental	21,273		479		(7,599)		14,153
General Casualty	141,624		(115,240)		(60,828)		(34,444)
Workers' Compensation	139,226		(178,138)		(115,648)		(154,560)
Marine, aviation and transit	67,831		(44,200)		(21,188)		2,443
Construction defect	22,182		(7,257)		(33,146)		(18,221)
Professional indemnity/ Directors & Officers	161,797		(11,159)		(130,957)		19,681
Motor	104,182		(109,962)		(34,215)		(39,995)
Property	22,178		(24,271)		(11,497)		(13,590)
All Other	50,271		(40,841)		(6,387)		3,043
Total	$	838,812	$	(552,124)	$	(573,127)	$	(286,439)

The significant drivers of the 2018 reduction in estimates of net ultimate losses are explained below.

Workers' Compensation - The $154.6 million reduction in estimates of net ultimate losses in our workers' compensation line of business arose across multiple portfolios, where reported incurred loss development was generally significantly less than expected. When actual development is less than expected for a sustained period of time across a significant volume of exposures, an updated actuarial analysis tends to indicate reductions in IBNR reserves. Updates to actuarial analysis, factoring in the less-than-expected reported incurred loss development for the year, is the primary driver of the reduction to our Workers' Compensation net ultimate loss estimates.

For certain of our portfolios, the lower than expected actual development was driven by significant proactive settlement activity on individual claimants where we were able to close open claims earlier than was indicated by our original payout patterns, and in other portfolios, based on the review of recent loss development activity we revised our actuarial development "tail factor" assumption, which led to a reduction in net ultimate losses. For example, in one portfolio we observed favorable incurred loss development, primarily relating to accident years 1995 through 2005 where we paid $22.7 million in loss payments to release a corresponding $37.0 million of associated case reserves for $14.3 million in favorable incurred loss development.

For recently acquired portfolios of workers' compensation business, we have utilized our subsidiary, Paladin Managed Care Services ("Paladin"), to assist us in reviewing claims. Paladin generally produces savings related to medical expense liabilities over and above savings achieved by prior vendors of such services, and the savings lead to actual development that is less than expected, thereby driving reductions to the estimates of net ultimate losses. In one particular program, our claims personnel pursued a proactive strategy of settling with numerous workers' compensation claimants whose injuries arose in recent accident years. For this portfolio, the claims team reduced the open inventory of claims by 78% during 2018. This reduction in exposure, when incorporated into an updated

actuarial analysis, led to a reduction in our estimate of ultimate net losses of $30.2 million, primarily relating to accident years 2010 through 2014.

We also continue to actively seek commutations on policies when possible, and where the commutation of the policy is settled at a level below the carried value of the loss reserves, we record a reduction in our estimates of net ultimate losses. During 2018, we completed 7 commutations across several portfolios that contributed to an $11.2 million the reduction in estimates of net ultimate losses.

Asbestos - The $64.9 million reduction in estimates of net ultimate losses in our asbestos line of business arose primarily due to one asbestos portfolio where lower than expected volume of claims reported and a lower than expected severity on claims settled in the period, when projected to net ultimate losses through actuarial methodologies, resulted in a significant reduction in estimates of net ultimate losses. The volume of claims reported was 3% less than expected and the average cost per claim was 5% less than expected. Across our other asbestos portfolios, we completed 8 commutations and 2 policy buy-backs contributing to a $9.5 million reduction in estimates of net ultimate losses.

Disclosures of Incurred and Paid Loss Development, IBNR, Claims Counts and Payout Percentages

The following tables provide a breakdown of gross and net losses and LAE reserves, consisting of Outstanding Loss Reserve ("OLR") and IBNR by line of business and adjustments for fair value resulting from business combinations, adjustments for where we elected the fair value option, deferred charge assets and ULAE, as of December 31, 2020 and 2019:


	2020
	Gross						Net
	OLR		IBNR		Total		OLR		IBNR		Total
	(in thousands of U.S. dollars)
Asbestos	$	544,438	$	1,234,101	$	1,778,539	$	464,102	$	1,122,021	$	1,586,123
Environmental	184,783		118,111		302,894		164,709		100,339		265,048
General casualty	610,437		1,279,991		1,890,428		492,039		1,247,662		1,739,701
Workers' compensation/personal accident	1,087,324		918,238		2,005,562		912,068		776,941		1,689,009
Marine, aviation and transit	271,469		73,081		344,550		229,464		56,414		285,878
Construction defect	23,380		85,578		108,958		23,109		83,039		106,148
Professional indemnity/Directors & Officers	764,768		336,705		1,101,473		526,333		307,349		833,682
Motor	619,682		355,044		974,726		451,097		283,576		734,673
Property	116,398		35,832		152,230		97,826		34,182		132,008
Other	217,746		204,819		422,565		141,448		121,895		263,343
	$	4,440,425	$	4,641,500	$	9,081,925	$	3,502,195	$	4,133,418	$	7,635,613
Fair value adjustments					(142,854)						(128,841)
Fair value adjustments - fair value option					(54,589)						(33,163)
Net deferred charge assets and gains on retroactive reinsurance					—						(218,722)

ULAE					350,600						333,913
Total					$	9,235,082					$	7,588,800


	2019
	Gross						Net
	OLR		IBNR		Total		OLR		IBNR		Total
	(in thousands of U.S. dollars)
Asbestos	$	542,681	$	1,373,678	$	1,916,359	$	490,117	$	1,271,982	$	1,762,099
Environmental	187,165		156,121		343,286		173,878		142,351		316,229
General casualty	501,863		489,129		990,992		399,396		421,426		820,822
Workers' compensation/personal accident	1,270,530		977,808		2,248,338		963,578		751,074		1,714,652
Marine, aviation and transit	290,067		121,577		411,644		244,611		100,135		344,746
Construction defect	29,772		98,312		128,084		29,245		94,888		124,133
Professional indemnity/Directors & Officers	693,760		265,490		959,250		485,478		170,926		656,404
Motor	480,668		233,806		714,474		317,829		165,543		483,372
Property	140,620		63,604		204,224		122,010		56,450		178,460
Other	269,956		165,882		435,838		208,647		97,573		306,220
	$	4,407,082	$	3,945,407	$	8,352,489	$	3,434,789	$	3,272,348	$	6,707,137
Fair value adjustments					(170,689)						(157,036)
Fair value adjustments - fair value option					(217,933)						(129,848)
Net deferred charge assets and gain liabilities on retroactive reinsurance					—						(259,587)

ULAE					331,494						331,494
Total					$	8,295,361					$	6,492,160

In addition to the breakdown of our Non-life Run-off reserves by line of business we also monitor our reserves by acquisition year. The acquisition year is the year in which the net reserves were acquired via a business acquisition or assumed via a retroactive reinsurance agreement. By analyzing the loss development tables by acquisition year on a prospective basis, the impact of the take-on positions from year to year does not distort the loss development tables.

The following table provides a summary of our net loss reserves, prior to provisions for bad debt, fair value adjustments, deferred charge assets and deferred gain liabilities and ULAE as of December 31, 2020, by year of acquisition and by significant line of business:


	Acquisition Year
	2010 and Prior		2011		2012		2013		2014		2015		2016		2017		2018		2019		2020		Total
Asbestos	$	142,028	$	—	$	—	$	7,767	$	—	$	—	$	407,958	$	726,901	$	1,105	$	277,947	$	—	$	1,563,706
Environmental	42,356		—		—		—		—		—		89,865		22,891		11,203		95,072		—		261,387
General casualty	52,582		13,270		9,983		16,696		31,610		34,704		3,727		44,551		228,419		218,995		1,077,908		1,732,445
Workers' compensation/personal accident	42,908		125,649		—		48,207		—		287,653		219,157		53,659		322,737		387,438		199,864		1,687,272
Marine, aviation and transit	8,760		2,747		—		(188)		10,592		1,616		32		77,321		106,431		56,709		19,848		283,868
Construction defect	43		—		—		—		—		36,258		14,289		18,836		—		36,709		—		106,135
Professional indemnity/Directors & Officers	7,539		9,564		23,210		—		20,942		—		76,314		—		331,676		130,906		232,934		833,085
Motor	12,452		201		276		—		1,465		13,147		—		3,710		260,797		17,899		422,321		732,268
Property	3,301		161		7,008		—		18,165		3,880		465		(114)		47,270		39,286		10,887		130,309
All Other	17,473		854		2,696		4,260		9,676		6,959		23,582		94,499		18,222		78,474		—		256,695
Total	$	329,442	$	152,446	$	43,173	$	76,742	$	92,450	$	384,217	$	835,389	$	1,042,254	$	1,327,860	$	1,339,435	$	1,963,762	$	7,587,170

The table below reconciles the net loss reserves, prior to provisions for bad debt, fair value adjustments, deferred charge assets and deferred gain liabilities and ULAE as of December 31, 2020, by significant line of business to the line of business table presented above:


	2020
	Total Net Reserves per all Acquisition Years		Provision for Bad Debt		Total Net Reserves
Asbestos	$	1,563,706	$	22,417	$	1,586,123
Environmental	261,387		3,661		265,048
General casualty	1,732,445		7,256		1,739,701
Workers' compensation/personal accident	1,687,272		1,737		1,689,009
Marine, aviation and transit	283,868		2,010		285,878
Construction defect	106,135		13		106,148
Professional indemnity/Directors & Officers	833,085		597		833,682
Motor	732,268		2,405		734,673
Property	130,309		1,699		132,008
All Other	256,695		6,648		263,343
Total	$	7,587,170	$	48,443	$	7,635,613

Loss development tables have been provided for acquisition years 2011 through 2020. In addition, for the acquisition years presented, we have also provided additional loss development tables for lines of business within those acquisition years which had net loss reserve balances that were deemed to be significant as of December 31, 2020 as follows:

•General casualty - 2018, 2019 and 2020 acquisition years;

•Workers' compensation - 2015, 2016, 2018 and 2019 acquisition years;

•Motor - 2018 and 2020 acquisition years; and

•Professional indemnity and directors and officers - 2018 and 2020 acquisition years.

Our Non-life Run-off segment is unique within the insurance industry in that legacy reserves are continuously being acquired and added to this segment through business acquisitions or through retroactive reinsurance agreements. Accordingly, it would not be appropriate to extrapolate redundancies or deficiencies into the future from the loss development tables provided below. Acquired and assumed reserves arising from business acquisitions and retroactive reinsurance agreements are presented on a full prospective basis.

The following tables set forth information about incurred and paid loss development, total IBNR reserves and cumulative loss frequency related to our 2011 through 2020 acquisition years within the Non-Life Run-off segment as of December 31, 2020. In addition, we have also presented loss development tables for the significant lines of business within certain acquisition years. The information related to incurred and paid loss development for the years ended December 31, 2011 through 2019 is presented as supplementary information and is therefore unaudited.

Business Acquired and Contracts Incepting in the Year Ended December 31, 2011


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance																							As of December 31, 2020
			For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired		2011 (unaudited)		2012 (unaudited)		2013 (unaudited)		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	597,263	$	621,819	$	589,004	$	489,877	$	426,777	$	375,227	$	319,423	$	274,136	$	261,234	$	240,808	$	229,458	$	17,493	112,837
2011	—		102		36		45		54		61		71		79		86		93		100		—		19
2012	—				122		11		10		10		10		17		18		17		17		—		7
2013	—						23		43		15		15		15		15		15		15		—		16
2014	—								1		3		3		3		18		15		14		2		14
2015	—										—		(2)		(2)		32		24		19		—		1
2016	—												2		(139)		(111)		(99)		(88)		7		2
2017	—														—		21		15		17		1		2
2018	—																7		8		8		1		1
2019	—																		—		2		1		1
2020	—																				2		1		1
	$	597,263																			$	229,564	$	17,506	112,901

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year			2011 (unaudited)		2012 (unaudited)		2013 (unaudited)		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior			$	58,934	$	98,969	$	90,711	$	24,238	$	19,370	$	27,563	$	19,697	$	31,108	$	56,741	$	77,051
2011			27		36		46		54		61		71		79		86		93		100
2012					6		10		10		10		10		17		17		17		17
2013							6		11		15		15		15		15		15		15
2014									1		3		3		3		4		7		7
2015											(1)		(2)		(2)		2		11		18
2016													2		(153)		(125)		(114)		(105)
2017															—		3		6		10
2018																	1		4		5
2019																			—		—
2020																					—
																					$	77,118
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance																					$	152,446

Business Acquired and Contracts Incepting in the Year Ended December 31, 2012


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance																					As of December 31, 2020
			For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired		2012 (unaudited)		2013 (unaudited)		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020			IBNR		Cumulative Number of Claims
2010 and Prior	$	326,229	$	328,419	$	321,295	$	312,510	$	297,081	$	286,660	$	277,778	$	269,004	$	263,472	$	252,318		$	10,889	47,773
2011	1,487		1,466		1,336		1,182		1,095		1,072		1,049		1,032		1,032		1,032			—		5
2012	55		81		49		363		344		406		397		167		167		167			—		6
2013	—				946		119		427		433		421		136		136		136			—		5
2014	(60)						2,991		3,108		1,552		1,300		1,195		1,146		1,068			1		7
2015	—								729		1,517		739		739		739		739			—		5
2016	(485)										67		1,266		1,113		1,059		445			37		2
2017	—												75		167		100		100			—		4
2018	(59)														—		154		74			4		1
2019	(123)																274		145			11		4
2020	—																		164			—		3
	$	327,044																	$	256,388		$	10,942	47,815

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year			2012 (unaudited)		2013 (unaudited)		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior			$	3,194	$	70,440	$	112,966	$	144,553	$	169,781	$	180,270	$	194,011	$	204,482	$	209,656
2011			120		496		742		866		928		990		1,032		1,032		1,032
2012			31		49		49		52		167		167		167		167		167
2013					109		119		136		136		136		136		136		136
2014							67		224		459		675		864		989		1,053
2015									112		117		739		739		739		739
2016											3		56		98		98		98
2017													13		43		100		100
2018															—		30		34
2019																	18		36
2020																			164
																			$	213,215
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance																	$	43,173

Business Acquired and Contracts Incepting in the Year Ended December 31, 2013


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance																	As of December 31, 2020
			For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired		2013 (unaudited)		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)				2020			IBNR	Cumulative Number of Claims
2010 and Prior	$	320,974	$	349,297	$	354,585	$	361,812	$	356,522	$	340,248	$	326,851	$	313,347	$	314,497		$	16,353	56,441
2011	96,929		102,288		100,482		100,243		95,848		87,913		86,403		85,919		81,616			2,700		11,185
2012	131,119		127,323		121,364		118,085		114,772		110,045		107,853		108,025		105,564			1,831		10,423
2013	13,062		90,739		91,634		88,920		85,791		81,732		80,036		80,091		79,174			1,073		5,656
2014	—				4,514		3,714		3,425		16,800		16,225		16,304		16,269			55		174
2015	—						265		280		982		329		250		237			42		2
2016	—								103		71		70		69		69			1		1
2017	—										30		13		13		13			—		1
2018	—												22		17		18			—		1
2019	—														13		15			—		1
2020	—																61			4		1
	$	562,084															$	597,533		$	22,059	83,886

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year			2013 (unaudited)		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior			$	74,418	$	134,409	$	186,762	$	222,891	$	229,942	$	243,755	$	249,023	$	258,436
2011			30,323		52,455		63,952		70,498		75,055		77,290		79,112		73,282
2012			33,361		59,095		74,663		86,916		92,445		96,780		99,781		98,096
2013			17,022		37,653		52,638		62,876		68,866		71,487		74,556		74,472
2014					993		1,747		2,256		15,804		15,959		16,123		16,164
2015							43		102		112		165		190		191
2016									34		64		65		66		67
2017											9		13		13		13
2018													13		17		18
2019															8		15
2020																	37
																	$	520,791
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance													$	76,742

Business Acquired and Contracts Incepting in the Year Ended December 31, 2014


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance													As of December 31, 2020
			For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)						2019 (unaudited)	2020			IBNR	Cumulative Number of Claims
2010 and Prior	$	142,341	$	133,678	$	123,973	$	155,274	$	142,256	$	141,058	$	145,889	$	144,874		$	6,454	12,014
2011	74,248		129,149		154,394		134,137		136,257		137,806		139,997		135,181			10,057		6,228
2012	141,597		147,347		178,577		187,062		179,745		165,821		162,740		160,769			10,449		6,393
2013	86,920		76,313		95,125		83,564		88,189		90,387		88,391		90,951			8,947		3,173
2014	—		13,802		9,554		14,506		7,438		6,590		6,954		7,098			1,708		1,112
2015	—				33,549		15,553		20,741		18,929		17,206		17,090			72		183
2016	—						330		1,108		4,594		771		724			89		45
2017	—								5,078		3,893		8,200		8,463			24		37
2018	—										6		5		82			—		19
2019	—												—		—			—		10
2020	—														—			—		6
	$	445,106													$	565,232		$	37,800	29,220

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year			2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior			$	36,509	$	82,699	$	103,197	$	118,857	$	120,309	$	121,847	$	127,622
2011			84,031		109,675		110,575		113,701		120,155		123,335		123,364
2012			47,495		90,307		120,910		130,001		130,105		133,900		133,026
2013			21,752		40,817		48,223		56,941		65,073		65,625		66,225
2014			1,462		2,504		3,293		3,989		6,147		6,660		6,654
2015					1,741		4,308		11,566		13,371		13,417		13,473
2016							20		556		558		561		559
2017									537		1,541		1,238		1,778
2018											5		5		81
2019													—		—
2020															—
															$	472,782
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance									$	92,450

Business Acquired and Contracts Incepting in the Year Ended December 31, 2015


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance									As of December 31, 2020
			For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)						2018 (unaudited)		2019 (unaudited)	2020			IBNR	Cumulative Number of Claims
2010 and Prior	$	1,003,949	$	933,328	$	640,324	$	594,466	$	564,502	$	521,598	$	505,379		$	49,461	13,557
2011	124,727		137,429		131,303		129,657		128,155		128,672		126,764			14,306		5,587
2012	179,136		187,488		197,895		201,017		194,277		193,553		192,426			18,110		4,885
2013	229,590		189,838		196,582		199,983		189,737		185,101		184,590			13,855		4,699
2014	144,392		143,193		137,668		142,937		137,541		152,478		147,567			7,413		7,783
2015	23,750		70,276		69,322		66,152		64,974		69,465		73,256			6,959		10,997
2016	—				14,872		13,141		13,440		14,576		12,868			2,178		14,283
2017	—						4,095		4,527		5,277		6,860			345		3,534
2018	—								3,055		1,889		1,805			985		400
2019	—										1,838		1,873			1,831		51
2020	—												1,951			1,962		3
	$	1,705,544											$	1,255,339		$	117,405	65,779

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year			2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior			$	32,819	$	83,350	$	134,737	$	166,983	$	195,205	$	220,984
2011			33,827		55,115		71,023		86,397		98,000		105,178
2012			52,728		94,831		119,520		142,358		158,620		168,213
2013			46,761		89,930		120,509		145,788		159,767		164,215
2014			30,747		64,475		91,016		109,451		125,619		133,094
2015			20,653		38,709		46,668		51,994		59,963		63,181
2016					5,603		7,371		8,687		9,861		10,321
2017							2,321		3,925		4,767		5,047
2018									567		862		820
2019											45		65
2020													4
													$	871,122
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance					$	384,217

Business Acquired and Contracts Incepting in the Year Ended December 31, 2015 - Workers' Compensation


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance									As of December 31, 2020
			For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)						2018 (unaudited)		2019 (unaudited)	2020			IBNR	Cumulative Number of Claims
2010 and Prior	$	953,178	$	868,509	$	569,692	$	518,764	$	490,534	$	449,380	$	434,422		$	40,504	8,605
2011	76,789		73,723		69,009		68,013		66,781		67,741		65,825			3,685		1,241
2012	120,298		110,007		108,251		106,625		100,187		99,212		98,733			4,613		1,809
2013	146,237		124,726		122,238		121,010		113,056		112,677		113,414			5,595		2,386
2014	82,141		86,852		82,038		83,095		78,389		78,948		80,307			1,513		3,686
2015	4,089		18,647		12,623		13,488		12,295		11,309		11,337			557		2,900
2016	—				873		955		583		536		514			52		38
2017	—						358		61		41		33			13		10
2018	—								—		5		3			—		1
2019	—										1		3			1		1
2020	—												—			—		—
	$	1,382,732											$	804,591		$	56,533	20,677

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year			2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior			$	20,630	$	65,008	$	107,906	$	132,025	$	155,329	$	177,205
2011			16,032		30,462		39,635		50,470		55,595		58,420
2012			25,103		52,851		66,092		79,367		88,369		91,332
2013			27,737		55,675		75,065		91,559		100,890		104,265
2014			17,824		38,051		53,308		65,561		72,696		75,781
2015			3,034		5,672		7,917		9,169		9,248		9,461
2016					134		363		417		447		452
2017							2		10		18		19
2018									—		1		2
2019											—		1
2020													—
													$	516,938
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance					$	287,653

Business Acquired and Contracts Incepting in the Year Ended December 31, 2016


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance							As of December 31, 2020
					For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired				2016 (unaudited)						2017 (unaudited)		2018 (unaudited)		2019 (unaudited)	2020			IBNR	Cumulative Number of Claims
2010 and Prior	$	1,304,938			$	1,316,544	$	1,346,575	$	1,321,289	$	1,322,161	$	1,361,353		$	305,042	24,449
2011	17,291				17,291		19,920		19,754		18,829		18,609			2,266		861
2012	13,717				13,717		17,020		14,765		12,717		13,037			1,829		809
2013	373				373		1,312		1,237		1,120		914			603		127
2014	391				391		1,380		1,056		869		817			310		57
2015	—				—		—		—		—		—			—		—
2016	—				—		—		—		—		—			—		—
2017	—						—		—		—		—			—		—
2018	—								—		—		—			—		—
2019	—										—		—			—		—
2020	—												—			—		—
	$	1,336,710											$	1,394,730		$	310,050	26,303

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
					For the Years Ended December 31,
Accident Year					2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior					$	101,098	$	222,703	$	331,218	$	445,770	$	536,987
2011					2,758		6,647		8,218		9,691		13,098
2012					2,734		5,206		6,461		7,587		8,492
2013					145		191		278		285		301
2014					178		207		284		366		463
2015					—		—		—		—		—
2016					—		—		—		—		—
2017							—		—		—		—
2018									—		—		—
2019											—		—
2020													—
													$	559,341
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	835,389

Business Acquired and Contracts Incepting in the Year Ended December 31, 2016 - Workers' Compensation


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance							As of December 31, 2020
					For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired				2016 (unaudited)						2017 (unaudited)		2018 (unaudited)		2019 (unaudited)	2020			IBNR	Cumulative Number of Claims
2010 and Prior	$	437,457			$	437,805	$	403,319	$	391,476	$	382,446	$	367,109		$	19,015	9,452
2011	15,376				15,376		16,399		16,501		16,327		16,472			1,374		469
2012	13,074				13,074		15,465		13,276		11,379		11,256			1,020		612
2013	—				—		—		—		—		—			—		—
2014	—				—		—		—		—		—			—		—
2015	—				—		—		—		—		—			—		—
2016	—				—		—		—		—		—			—		—
2017	—						—		—		—		—			—		—
2018	—								—		—		—			—		—
2019	—										—		—			—		—
2020	—												—			—		—
	$	465,907											$	394,837		$	21,409	10,533

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
					For the Years Ended December 31,
Accident Year					2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior					$	35,518	$	65,264	$	90,599	$	127,081	$	155,433
2011					2,631		5,871		7,305		8,756		12,130
2012					2,638		5,028		6,247		7,382		8,117
2013					—		—		—		—		—
2014					—		—		—		—		—
2015					—		—		—		—		—
2016					—		—		—		—		—
2017							—		—		—		—
2018									—		—		—
2019											—		—
2020													—
													$	175,680
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	219,157

Business Acquired and Contracts Incepting in the Year Ended December 31, 2017


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired					2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	1,507,609				$	1,433,301	$	1,351,451	$	1,364,113	$	1,349,226	$	749,197	31,566
2011	40,743					29,274		25,389		27,316		26,942		5,834		8
2012	43,653					35,470		31,238		29,456		28,485		3,744		10
2013	35,671					30,338		28,139		24,707		29,829		1,860		11
2014	32,858					20,315		16,984		15,996		16,342		2,287		20
2015	8,808					6,494		7,002		6,295		6,043		234		8
2016	362					(4)		126		919		1,074		394		3
2017	—					174		—		—		—		—		1
2018	—							—		—		—		—		—
2019	—									—		—		—		—
2020	—											—		—		—
	$	1,669,704										$	1,457,941	$	763,550	31,627

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Years Ended December 31,
Accident Year						2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior						$	85,514	$	175,630	$	257,071	$	334,586
2011						4,125		9,257		12,971		15,407
2012						10,348		15,372		18,605		21,076
2013						9,509		15,714		21,280		25,832
2014						6,482		8,986		11,559		12,668
2015						1,361		3,720		4,687		5,582
2016						(56)		66		434		536
2017						4		—		—		—
2018								—		—		—
2019										—		—
2020												—
												$	415,687
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	1,042,254

Business Acquired and Contracts Incepting in the Year Ended December 31, 2018


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	662,009				$	497,101	$	476,164	$	409,505	$	50,970	223,572
2011	164,556					150,408		150,388		147,796		16,240		14,072
2012	232,116					224,955		224,959		225,528		29,903		14,382
2013	272,732					274,377		268,237		250,013		35,175		16,126
2014	419,593					462,858		439,396		415,829		38,688		19,463
2015	365,429					483,489		480,093		496,187		62,476		24,768
2016	173,309					175,428		178,061		169,872		36,090		2,026
2017	207,040					207,190		205,466		204,490		55,056		4,163
2018	315,659					315,659		285,038		282,279		53,287		4,929
2019	—							68,271		68,041		9,762		1,634
2020	—									—		—		—
	$	2,812,443								$	2,669,540	$	387,647	325,135

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior						$	50,515	$	86,132	$	81,554
2011						26,236		53,151		65,522
2012						31,772		81,356		106,297
2013						41,544		96,968		133,398
2014						90,689		188,721		235,787
2015						95,688		199,373		269,559
2016						6,854		63,982		93,705
2017						56		72,800		113,770
2018						—		139,815		191,442
2019								39,099		50,646
2020										—
										$	1,341,680
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	1,327,860

Business Acquired and Contracts Incepting in the Year Ended December 31, 2018 - General Casualty


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	130,049				$	74,102	$	70,937	$	67,933	$	4,827	47,893
2011	18,044					16,554		16,650		15,855		151		1,421
2012	37,454					33,433		29,123		29,760		3,270		1,593
2013	43,301					56,092		46,596		46,999		4,352		1,596
2014	66,562					80,896		74,947		68,535		5,802		2,291
2015	79,191					94,124		104,790		109,694		14,188		3,594
2016	28,825					28,825		36,585		36,684		10,075		253
2017	37,209					37,209		41,664		43,174		14,554		230
2018	39,888					39,888		40,753		39,157		11,605		182
2019	—							6,767		6,187		394		34
2020	—									—		—		—
	$	480,523								$	463,978	$	69,218	59,087

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior						$	9,164	$	18,817	$	29,840
2011						2,349		7,115		11,018
2012						1,281		11,453		14,383
2013						10,404		19,938		27,717
2014						13,766		27,833		41,899
2015						15,494		31,535		49,860
2016						—		14,109		18,916
2017						—		11,048		21,130
2018						—		8,879		17,455
2019								2,373		3,341
2020										—
										$	235,559
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	228,419

Business Acquired and Contracts Incepting in the Year Ended December 31, 2018 - Workers' Compensation


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	131,873				$	122,831	$	129,280	$	131,775	$	39,843	2,098
2011	29,897					28,685		29,981		27,203		9,067		401
2012	28,749					29,181		27,676		26,833		10,597		468
2013	38,029					38,554		38,093		35,212		13,243		869
2014	65,049					66,346		57,163		52,797		17,605		1,345
2015	38,851					39,379		35,235		33,253		13,026		1,464
2016	44,686					44,686		38,945		37,714		15,857		892
2017	52,360					52,360		49,156		45,529		23,004		998
2018	65,075					65,075		60,923		59,768		19,310		886
2019	—							20,889		21,417		4,445		383
2020	—									—		—		—
	$	494,569								$	471,501	$	165,997	9,804

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior						$	604	$	11,788	$	21,726
2011						2,281		5,592		9,418
2012						516		5,508		7,941
2013						1,525		7,773		12,280
2014						3,260		14,687		21,380
2015						1,403		4,355		9,844
2016						—		3,666		7,176
2017						—		5,900		9,088
2018						—		28,725		34,317
2019								13,483		15,594
2020										—
										$	148,764
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	322,737

Business Acquired and Contracts Incepting in the Year Ended December 31, 2018 - Motor


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	43,818				$	31,489	$	30,036	$	33,230	$	2,599	1,323
2011	48,231					38,092		37,707		36,301		2,031		1,239
2012	65,427					58,006		63,786		59,276		5,862		1,641
2013	78,456					71,276		65,012		55,345		5,744		683
2014	116,677					103,761		90,902		84,459		5,243		1,260
2015	135,855					133,493		132,167		132,165		15,246		1,510
2016	93,164					95,283		97,040		91,600		9,824		732
2017	100,321					100,471		99,135		102,038		16,628		2,797
2018	180,471					180,471		157,556		160,143		21,609		3,731
2019	—							39,757		39,647		4,955		1,200
2020	—									—		—		—
	$	862,420								$	794,204	$	89,741	16,116

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior						$	7,460	$	13,722	$	16,655
2011						6,060		12,980		15,464
2012						12,380		24,433		31,136
2013						11,114		29,311		35,186
2014						22,393		49,089		60,254
2015						21,712		61,928		84,976
2016						6,854		43,851		65,287
2017						56		48,661		73,440
2018						—		86,861		120,041
2019								22,687		30,968
2020										—
										$	533,407
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	260,797

Business Acquired and Contracts Incepting in the Year Ended December 31, 2018 - Professional Indemnity/Directors & Officers


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	236,568				$	137,394	$	147,383	$	143,585	$	(3,639)	56,674
2011	46,512					52,553		48,884		51,600		3,185		3,762
2012	57,937					70,636		69,641		74,884		4,399		3,285
2013	59,457					63,284		78,933		76,291		10,543		3,257
2014	88,173					111,193		107,411		114,621		11,523		3,619
2015	47,337					100,975		81,272		85,394		15,074		3,990
2016	—					—		—		—		—		—
2017	—					—		—		—		—		—
2018	—					—		—		—		—		—
2019	—							—		—		—		—
2020	—									—		—		—
	$	535,984								$	546,375	$	41,085	74,587

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior						$	29,359	$	54,157	$	28,528
2011						13,123		20,017		22,250
2012						16,382		23,237		33,794
2013						10,987		21,919		34,269
2014						22,734		39,601		61,024
2015						14,245		26,595		34,834
2016						—		—		—
2017						—		—		—
2018						—		—		—
2019								—		—
2020										—
										$	214,699
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	331,676

Business Acquired and Contracts Incepting in the Year Ended December 31, 2019


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2019 (unaudited)		2020			IBNR		Cumulative Number of Claims
2010 and Prior	$	652,608				$	630,171	$	628,495		$	272,910	74,742
2011	49,873					40,554		35,876			8,773		15,218
2012	73,098					54,301		49,349			12,905		12,329
2013	112,031					93,213		88,066			29,931		14,952
2014	137,324					137,478		127,704			53,814		17,624
2015	179,651					188,833		196,007			80,816		25,081
2016	253,099					295,011		260,473			118,653		32,057
2017	116,386					116,386		116,386			116,386		2
2018	162,744					162,744		162,744			162,744		2
2019	—					54,571		64,595			6,155		1,679
2020	—							27,975			5,483		1,020
	$	1,736,814						$	1,757,670		$	868,570	194,706

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2019 (unaudited)		2020
2010 and Prior						$	26,817	$	106,195
2011						4,786		8,100
2012						6,886		9,565
2013						13,540		20,906
2014						28,188		47,310
2015						33,417		63,994
2016						56,125		84,592
2017						—		—
2018						—		—
2019						25,595		55,912
2020								21,661
								$	418,235
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	1,339,435

Business Acquired and Contracts Incepting in the Year Ended December 31, 2019 - General Casualty


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2019 (unaudited)		2020			IBNR		Cumulative Number of Claims
2010 and Prior	$	12,765				$	9,788	$	9,994		$	1,620	1,424
2011	12,321					9,490		7,979			3,587		796
2012	18,107					14,471		13,786			8,214		1,165
2013	23,750					18,230		20,960			8,897		313
2014	33,767					31,181		29,341			16,377		905
2015	58,818					45,936		41,158			18,055		2,003
2016	48,606					64,159		58,061			32,692		3,134
2017	32,188					32,188		32,188			32,188		1
2018	45,010					45,010		45,010			45,010		1
2019	—					1,750		1,873			510		225
2020	—							1,118			267		411
	$	285,332						$	261,468		$	167,417	10,378

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2019 (unaudited)		2020
2010 and Prior						$	2,230	$	2,894
2011						810		1,869
2012						3,326		6,604
2013						3,499		5,813
2014						3,878		8,155
2015						4,421		5,121
2016						4,894		10,723
2017						—		—
2018						—		—
2019						—		841
2020								453
								$	42,473
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	218,995

Business Acquired and Contracts Incepting in the Year Ended December 31, 2019 - Workers' Compensation


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2019 (unaudited)		2020			IBNR		Cumulative Number of Claims
2010 and Prior	$	5,860				$	4,420	$	4,551		$	1,938	9,869
2011	2,474					2,410		2,409			2,342		1,082
2012	6,280					6,176		6,176			6,991		1,640
2013	16,738					18,339		15,980			14,415		2,897
2014	35,023					35,426		35,556			31,501		3,410
2015	57,194					56,171		57,314			48,840		4,802
2016	87,702					85,530		84,862			70,769		4,829
2017	84,197					84,197		84,197			84,197		1
2018	117,734					117,734		117,734			117,734		1
2019	—					—		—			—		—
2020	—							2,045			—		189
	$	413,202						$	410,824		$	378,727	28,720

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2019 (unaudited)		2020
2010 and Prior						$	607	$	696
2011						22		23
2012						22		63
2013						458		572
2014						3,080		3,443
2015						3,549		6,325
2016						7,337		12,137
2017						—		—
2018						—		—
2019						—		—
2020								127
								$	23,386
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	387,438

Business Acquired and Contracts Incepting in the Year Ended December 31, 2020


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
								For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired					2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	256,228				$	169,601	$	91,688	47
2011	26,488					26,983		25,162		36
2012	58,128					58,241		53,749		74
2013	68,683					63,922		47,944		140
2014	100,054					102,600		83,249		201
2015	161,383					161,352		113,476		384
2016	210,661					205,305		120,481		816
2017	316,751					342,330		168,832		1,770
2018	432,590					575,706		305,471		3,108
2019	344,495					343,168		301,463		1,351
2020	166,946					168,091		144,090		1,481
	$	2,142,407				$	2,217,299	$	1,455,605	9,408

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Years Ended December 31,
Accident Year						2020
2010 and Prior						$	2,310
2011						54
2012						601
2013						4,283
2014						5,975
2015						12,253
2016						33,985
2017						73,001
2018						111,871
2019						1,509
2020						7,695
						253,537
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	1,963,762

Business Acquired and Contracts Incepting in the Year Ended December 31, 2020 - General Casualty


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
								For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired					2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	43,511				$	43,849	$	36,455	36
2011	26,434					26,928		25,133		29
2012	55,478					55,591		51,130		60
2013	60,872					56,111		41,186		122
2014	87,620					90,182		71,022		185
2015	140,583					139,947		96,032		280
2016	142,395					143,156		100,293		394
2017	142,862					137,097		112,135		439
2018	141,803					138,267		133,942		316
2019	202,521					201,174		179,284		388
2020	83,021					82,598		77,737		338
	$	1,127,100				$	1,114,900	$	924,349	2,587

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Years Ended December 31,
Accident Year						2020
2010 and Prior						$	522
2011						54
2012						601
2013						3,258
2014						5,983
2015						10,230
2016						9,125
2017						4,149
2018						400
2019						203
2020						2,467
						36,992
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	1,077,908

Business Acquired and Contracts Incepting in the Year Ended December 31, 2020 - Motor


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
								For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired					2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	—				$	—	$	—	—
2011	—					—		—		—
2012	—					—		—		—
2013	—					—		—		—
2014	—					—		—		—
2015	2,397					3,018		603		19
2016	48,505					42,420		2,779		221
2017	154,070					185,445		38,279		1,099
2018	250,028					397,413		145,623		2,204
2019	—					—		—		—
2020	—					—		—		—
	$	455,000				$	628,296	$	187,284	3,543

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Years Ended December 31,
Accident Year						2020
2010 and Prior						$	—
2011						—
2012						—
2013						—
2014						—
2015						2,012
2016						24,804
2017						68,712
2018						110,447
2019						—
2020						—
						205,975
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	422,321

Business Acquired and Contracts Incepting in the Year Ended December 31, 2020 - Professional Indemnity/Directors & Officers


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
								For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired					2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	4,680				$	4,678	$	4,679	1
2011	44					44		44		3
2012	2,593					2,593		2,584		4
2013	7,791					7,791		6,745		6
2014	11,949					11,949		11,947		4
2015	16,120					16,120		15,769		4
2016	16,259					16,216		16,053		9
2017	17,212					17,206		16,906		41
2018	25,323					25,290		19,209		115
2019	99,460					99,350		92,944		135
2020	34,548					34,757		30,144		79
	$	235,979				$	235,994	$	217,024	401

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Years Ended December 31,
Accident Year						2020
2010 and Prior						$	—
2011						—
2012						—
2013						1,025
2014						—
2015						6
2016						1
2017						5
2018						475
2019						410
2020						1,138
						3,060
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	232,934

Annual Historical Duration of Claims

The following is unaudited supplementary information, which presents the annual percentage payout since the year of acquisition, by year of acquisition and significant line of business within each acquisition year:


	Annual Percentage Payout of Incurred Losses since Year of Acquisition, Net of Reinsurance
Year of Acquisition	Year 1		Year 2		Year 3		Year 4		Year 5		Year 6		Year 7		Year 8		Year 9		Year 10


2011 - All lines of business	25.68	%	17.45	%	(3.59)	%	(28.95)	%	(2.12)	%	3.57	%	(3.49)	%	4.99	%	11.18	%	8.86	%
2012 - All lines of business	1.30	%	26.42	%	16.71	%	12.48	%	10.00	%	4.47	%	5.48	%	4.17	%	2.12	%
2013 - All lines of business	25.96	%	21.67	%	15.93	%	11.01	%	6.15	%	3.89	%	2.24	%	0.32	%
2014 - All lines of business	33.84	%	24.15	%	11.11	%	8.07	%	3.74	%	1.65	%	1.10	%
2015 - All lines of business	17.33	%	17.09	%	12.84	%	9.80	%	7.69	%	4.65	%
2015 - Workers' compensation	13.72	%	17.09	%	12.73	%	9.73	%	6.71	%	4.27	%
2016 - All lines of business	7.67	%	9.18	%	7.99	%	8.41	%	6.86	%
2016 - Workers' Compensation	10.33	%	8.96	%	7.09	%	9.89	%	8.22	%
2017 - All lines of business	8.04	%	7.64	%	6.71	%	6.11	%

2018 - All lines of business	12.86	%	25.40	%	12.00	%
2018 - General Casualty	11.31	%	21.69	%	17.77	%
2018 - Workers' Compensation	2.03	%	19.49	%	10.03	%

2018 - Professional Indemnity/Directors & Officers	19.55	%	14.40	%	5.34	%
2018 - Motor	11.08	%	38.47	%	17.61	%
2019 - All lines of business	11.11	%	12.68	%
2019 - General Casualty	8.82	%	7.43	%
2019 - Workers' Compensation	3.67	%	2.02	%
2020 - All lines of business	11.43	%

2020 - General Casualty	3.32	%
2020 - Motor	32.78	%
2020 - Professional Indemnity/Directors & Officers	1.30	%

The negative payout percentages in the table above for years 3, 4, 5, and 7 within the 2011 year of acquisition were primarily due to ceded paid losses exceeding the assumed paid losses as a result of commutations completed with several reinsurers covering the exposures assumed by one of our reinsurance subsidiaries that we acquired in 2011. For the specific years referenced above, we collected more paid recoveries from our reinsurers than the losses we paid on the assumed exposures, and as such, the calculated annual payout percentages were negative.

Atrium (Classified as held-for-sale as of December 31, 2020)

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Balance as of January 1	$	231,672	$	241,284	$	240,873
Less: reinsurance reserves recoverable	28,816		38,768		40,531

Less: cumulative effect of change in accounting principal on allowance for estimated uncollectible reinsurance (1)	851		—		—
Net balance as of January 1	202,005		202,516		200,342
Net incurred losses and LAE:
Current period	93,471		85,027		83,627
Prior periods	(6,245)		(7,751)		(13,817)
Total net incurred losses and LAE	87,226		77,276		69,810
Net paid losses:
Current period	(33,724)		(34,617)		(35,537)
Prior periods	(40,196)		(43,572)		(28,969)
Total net paid losses	(73,920)		(78,189)		(64,506)
Effect of exchange rate movement	1,497		1,253		(3,130)
Reclassification to assets and liabilities held-for-sale	(216,808)		—		—
Net balance as of December 31	—		202,856		202,516
Plus: reinsurance reserves recoverable (2)	—		28,816		38,768
Balance as of December 31	$	—	$	231,672	$	241,284

(1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details.

(2) Net of allowance for estimated uncollectible reinsurance.

Net incurred losses and LAE in the Atrium segment for the years ended December 31, 2020, December 31, 2019 and 2018 were as follows:


	2020						2019						2018
	Prior Period		Current Period		Total		Prior Period		Current Period		Total		Prior Period		Current Period		Total
Net losses paid	$	40,196	$	33,724	$	73,920	$	43,572	$	34,617	$	78,189	$	28,969	$	35,537	$	64,506
Net change in case and LAE reserves(1)	(14,145)		21,390		7,245		(13,278)		16,812		3,534		(10,161)		16,492		6,331
Net change in IBNR reserves(2)	(31,773)		38,434		6,661		(38,380)		33,598		(4,782)		(27,507)		31,598		4,091
Increase (reduction) in estimates of net ultimate losses	(5,722)		93,548		87,826		(8,086)		85,027		76,941		(8,699)		83,627		74,928

Increase (reduction) in provisions for unallocated LAE (3)	48		(77)		(29)		—		—		—		—		—		—
Amortization of fair value adjustments (4)	(571)		—		(571)		335		—		335		(5,118)		—		(5,118)
Net incurred losses and LAE	$	(6,245)	$	93,471	$	87,226	$	(7,751)	$	85,027	$	77,276	$	(13,817)	$	83,627	$	69,810

(2)Represents the gross change in our actuarial estimates of IBNR, less amounts recoverable.

(3) Represents the change in the estimate of the total future costs to administer the claims.

(4) Relates to the amortization of fair value adjustments associated with the acquisition of companies.

The increase in net incurred losses and LAE of $10.0 million in 2020 was primarily driven by $18.4 million of losses related to the COVID-19 pandemic, primarily from accident and health business, partially offset by overall improved loss experience, within other lines of business and lower catastrophe activity on the business we write.

The following table provides a breakdown of the gross and net losses and LAE reserves by line of business and the fair value adjustments recorded on the acquired gross and net losses and LAE reserves and ULAE as of December 31, 2019 for the Atrium segment. The breakdown as of December 31, 2020 has not been disclosed below since we have classified the Atrium segment as held-for-sale as discussed in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations."


	2019
	Gross						Net
	OLR		IBNR		Total		OLR		IBNR		Total
	(in thousands of U.S. dollars)
Marine, Aviation and Transit	$	24,668	$	34,156	$	58,824	$	21,012	$	24,829	$	45,841
Binding Authorities	31,507		54,039		85,546		29,590		51,984		81,574
Reinsurance	18,385		29,533		47,918		16,209		23,338		39,547
Accident and Health	5,460		7,880		13,340		4,735		7,469		12,204
Non-Marine Direct and Facultative	9,121		10,935		20,056		8,584		9,637		18,221
Total	$	89,141	$	136,543	$	225,684	$	80,130	$	117,257	$	197,387
Fair value adjustments					3,700						3,181
ULAE					2,288						2,288
Total					$	231,672					$	202,856

StarStone

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Balance as of January 1	$	1,318,294	$	1,247,989	$	910,143
Less: reinsurance reserves recoverable	355,194		303,381		275,012

Less: cumulative effect of change in accounting principal on allowance for estimated uncollectible reinsurance (1)	495		—		—
Net balance as of January 1	962,605		944,608		635,131
Net incurred losses and LAE:
Current period	263,562		354,884		422,191
Prior periods	3,176		114,356		120,889
Total net incurred losses and LAE	266,738		469,240		543,080
Net paid losses:
Current period	(26,831)		(75,458)		(137,390)
Prior periods	(300,037)		(375,377)		(289,981)
Total net paid losses	(326,868)		(450,835)		(427,371)
Effect of exchange rate movement	23,421		87		(9,481)
Acquired on purchase of subsidiaries	—		—		192,981
Assumed business	—		—		10,268
Ceded business	—		—		—
Net balance as of December 31	925,896		963,100		944,608
Plus: reinsurance reserves recoverable (2)	402,060		355,194		303,381
Balance as of December 31	$	1,327,956	$	1,318,294	$	1,247,989

(1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details.

(2) Net of allowance for estimated uncollectible reinsurance.

Net incurred losses and LAE in the StarStone segment for the years ended December 31, 2020, December 31, 2019 and 2018 were as follows:


	2020						2019						2018
	Prior Period		Current Period		Total		Prior Period		Current Period		Total		Prior Period		Current Period		Total
Net losses paid	$	300,037	$	26,831	$	326,868	$	375,377	$	75,458	$	450,835	$	289,981	$	137,390	$	427,371
Net change in case and LAE reserves (1)	(130,502)		35,458		(95,044)		(95,183)		90,497		(4,686)		(77,821)		141,682		63,861
Net change in IBNR reserves (2)	(165,909)		183,563		17,654		(163,340)		185,361		22,021		(87,963)		134,464		46,501
Increase in estimates of net ultimate losses	3,626		245,852		249,478		116,854		351,316		468,170		124,197		413,536		537,733
Increase (reduction) in provisions for unallocated LAE (3)	(466)		17,710		17,244		(2,666)		3,568		902		(3,042)		8,655		5,613
Amortization of deferred charge assets and deferred gain liabilities (4)	606		—		606		—		—		—		—		—		—
Amortization of fair value adjustments (5)	(590)		—		(590)		168		—		168		(266)		—		(266)
Net incurred losses and LAE	$	3,176	$	263,562	$	266,738	$	114,356	$	354,884	$	469,240	$	120,889	$	422,191	$	543,080

(2) Represents the gross change in our actuarial estimates of IBNR, less amounts recoverable.

(3) Represents the change in the estimate of the total future costs to administer the claims.

(4) Relates to the amortization of deferred charge assets and deferred gain liabilities on retroactive reinsurance contracts.

(5) Relates to the amortization of fair value adjustments associated with the acquisition of companies.

The decrease in net incurred losses and LAE of $202.5 million in 2020 was mainly driven by our strategy to exit certain lines of business in 2019 and StarStone International being placed into an orderly run-off in 2020; partially offset by $52.8 million of losses relating to the COVID-19 pandemic. The decrease in net incurred losses and LAE of $73.8 million in 2019 was primarily driven by our strategy to exit certain lines of business.

Disclosures of Incurred and Paid Loss Development, IBNR, Claims Counts and Payout Percentages

The following tables provide a breakdown of the gross and net losses and LAE reserves by line of business and the fair value adjustments recorded on the acquired gross and net losses and LAE reserves and ULAE as of December 31, 2020 and 2019:


	2020
	Gross						Net
	OLR		IBNR		Total		OLR		IBNR		Total
	(in thousands of U.S. dollars)
Casualty	$	115,295	$	276,941	$	392,236	$	98,721	$	232,433	$	331,154
Marine	142,631		174,015		316,646		119,628		132,482		252,110
Property	322,735		117,240		439,975		141,089		81,459		222,548
Aerospace	84,515		36,178		120,693		42,100		18,240		60,340
Workers' Compensation	12,044		11,589		23,633		12,044		11,589		23,633
Total	$	677,220	$	615,963	$	1,293,183	$	413,582	$	476,203	$	889,785
Fair value adjustments					(329)						1,010
ULAE					35,102						35,101
Total					$	1,327,956					$	925,896


	2019
	Gross						Net
	OLR		IBNR		Total		OLR		IBNR		Total
	(in thousands of U.S. dollars)
Casualty	$	121,945	$	210,969	$	332,914	$	108,543	$	204,800	$	313,343
Marine	189,355		161,379		350,734		158,252		128,242		286,494
Property	341,677		131,596		473,273		150,559		87,653		238,212
Aerospace	75,764		32,325		108,089		47,256		22,389		69,645
Workers' Compensation	15,089		19,865		34,954		15,089		19,865		34,954
Total	$	743,830	$	556,134	$	1,299,964	$	479,699	$	462,949	$	942,648
Fair value adjustments					(522)						1,600
ULAE					18,852						18,852
Total					$	1,318,294					$	963,100

The following tables set forth information about incurred and paid loss development, total IBNR reserves and cumulative loss frequency related to all the individual lines of business within the StarStone segment as of December 31, 2020. The information related to incurred and paid loss development for the years ended December 31, 2014 through 2019 is presented as supplementary information and is therefore unaudited. The information within the tables below is presented on a prospective basis from the date of our acquisition of StarStone on April 1, 2014 since providing pre-acquisition incurred and paid losses by accident year for years prior to 2014 was determined to be impracticable due to significant data limitations. Following our sale of StarStone U.S. to Core Specialty, which was completed on November 30, 2020, the incurred and paid loss development tables presented below for all of the individual lines of business within the StarStone segment have been restated to exclude the historical incurred and paid loss development related to StarStone U.S.

Casualty


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance															As of December 31, 2020
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR(1)		Cumulative Number of Claims
2010 and Prior	$	100,449	$	101,217	$	101,444	$	101,801	$	102,539	$	102,317	$	102,661	$	19	4,322
2011	16,244		18,740		19,681		19,103		27,703		27,859		28,027		429		2,962
2012	39,797		33,853		30,788		28,482		33,511		36,159		37,072		3,418		3,521
2013	51,458		47,304		54,282		53,493		56,145		63,323		67,638		9,044		4,821
2014	66,094		67,141		67,461		66,559		66,585		75,513		72,097		10,495		4,863
2015			76,470		82,050		81,685		92,904		99,425		101,191		13,037		4,323
2016					92,406		95,726		111,020		135,670		128,139		25,293		3,825
2017							100,585		135,743		161,288		166,472		34,822		3,899
2018									87,781		101,381		106,014		39,329		2,929
2019											42,595		59,902		23,758		2,581
2020													98,738		72,789		1,582
											Total		$	967,951	$	232,433	39,628
(1) Total of IBNR plus expected development on reported losses.
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior	$	99,643	$	101,181	$	101,326	$	101,712	$	101,783	$	101,813	$	101,886
2011	12,394		15,941		18,354		18,760		27,385		27,401		27,426
2012	13,336		20,634		22,746		23,711		32,644		32,666		32,706
2013	16,373		22,131		35,799		38,866		42,123		48,898		52,333
2014	4,318		16,141		27,043		36,802		46,654		49,571		51,949
2015			6,439		21,503		36,971		50,598		69,948		75,875
2016					4,206		32,864		59,074		76,175		92,223
2017							7,712		41,896		87,902		114,062
2018									18,747		34,762		54,000
2019											4,721		26,235
2020													8,102
											Total		$	636,797
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance													$	331,154

The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below:


	2020
Liabilities for unpaid losses and allocated LAE, net of reinsurance	$	331,154
Reinsurance recoverable on unpaid losses	61,082
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$	392,236

The following is unaudited supplementary information for average annual historical duration of claims:


	Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance
	Year 1		Year 2		Year 3		Year 4		Year 5		Year 6		Year 7		Year 8		Year 9		Year 10
Casualty	7.72	%	20.87	%	17.53	%	15.99	%	9.96	%	4.35	%	7.85	%	9.00	%	0.06	%	0.08	%

Marine


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance															As of December 31, 2020
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR(1)		Cumulative Number of Claims
2010 and Prior	$	50,395	$	47,336	$	47,194	$	47,287	$	47,175	$	47,213	$	46,828	$	62	3,037
2011	29,890		28,190		27,767		27,824		28,162		27,956		28,075		229		1,966
2012	48,204		52,010		51,710		50,435		51,231		49,176		48,706		307		2,431
2013	63,442		55,981		53,783		54,790		58,209		64,399		63,323		926		2,202
2014	50,959		54,370		49,449		56,049		51,642		51,062		49,676		1,003		3,944
2015			70,492		70,160		80,196		81,864		83,646		80,438		1,612		5,606
2016					80,830		83,187		88,459		88,023		89,309		4,150		6,658
2017							125,976		158,450		166,304		162,629		7,959		8,352
2018									164,461		164,042		161,831		16,444		10,123
2019											152,423		158,919		39,463		7,015
2020													84,427		60,327		2,703
											Total		$	974,161	$	132,482	54,037
(1) Total of IBNR plus expected development on reported losses.
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior	$	44,212	$	46,360	$	46,464	$	46,470	$	46,563	$	46,682	$	46,709
2011	24,599		25,686		26,688		26,942		27,057		27,082		27,285
2012	38,570		42,787		44,681		45,498		45,951		46,178		47,452
2013	29,436		38,880		43,027		45,575		47,698		57,539		62,037
2014	11,037		25,306		33,076		37,594		43,323		44,727		44,740
2015			10,234		30,143		50,376		56,557		59,918		62,401
2016					11,669		41,875		58,438		73,778		76,534
2017							23,986		68,233		107,787		125,335
2018									40,698		103,930		129,632
2019											33,196		84,414
2020													15,512
											Total		$	722,051
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance													$	252,110

The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below:


	2020
Liabilities for unpaid losses and allocated LAE, net of reinsurance	$	252,110
Reinsurance recoverable on unpaid losses	64,536
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$	316,646

The following is unaudited supplementary information for average annual historical duration of claims:


	Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance
	Year 1		Year 2		Year 3		Year 4		Year 5		Year 6		Year 7		Year 8		Year 9		Year 10
Marine	18.17	%	30.97	%	19.08	%	9.99	%	5.02	%	2.46	%	3.48	%	2.04	%	0.99	%	0.39	%

Property


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance															As of December 31, 2020
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR(1)		Cumulative Number of Claims
2010 and Prior	$	190,649	$	188,537	$	187,286	$	187,846	$	188,778	$	189,079	$	190,667	$	13	4,485
2011	91,712		90,272		90,328		90,018		89,918		90,259		90,406		88		1,635
2012	66,137		62,119		61,243		62,177		59,201		59,463		58,247		133		1,516
2013	78,501		65,608		65,394		64,521		62,711		61,114		61,383		152		1,955
2014	59,390		44,130		43,631		44,081		41,968		41,226		40,612		794		2,125
2015			75,514		73,946		67,944		67,733		68,678		69,314		1,377		11,435
2016					83,622		91,680		92,038		91,956		94,450		1,361		14,167
2017							152,172		169,673		181,855		171,673		4,429		14,553
2018									161,507		172,640		174,137		11,123		11,891
2019											116,634		117,009		22,609		6,166
2020													71,147		39,380		1,338
											Total		$	1,139,045	$	81,459	71,266
(1) Total of IBNR plus expected development on reported losses.
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior	$	183,649	$	186,876	$	187,040	$	187,264	$	187,285	$	187,300	$	188,080
2011	87,937		89,149		89,662		89,894		89,894		89,940		90,110
2012	48,322		52,442		54,681		55,672		55,895		58,099		58,100
2013	31,000		46,556		51,431		53,548		59,756		60,916		61,060
2014	5,517		18,945		31,854		34,869		36,461		37,609		39,681
2015			8,756		25,890		52,799		61,347		62,237		62,826
2016					23,803		54,188		72,244		81,904		83,577
2017							34,961		96,151		137,569		146,340
2018									60,944		93,275		126,763
2019											19,461		52,637
2020													7,323
											Total		$	916,497
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance													$	222,548

The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below:


	2020
Liabilities for unpaid losses and allocated LAE, net of reinsurance	$	222,548
Reinsurance recoverable on unpaid losses	217,427
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$	439,975

The following is unaudited supplementary information for average annual historical duration of claims:


	Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance
	Year 1		Year 2		Year 3		Year 4		Year 5		Year 6		Year 7		Year 8		Year 9		Year 10
Property	19.10	%	28.75	%	26.40	%	8.35	%	2.47	%	2.69	%	1.55	%	1.01	%	0.02	%	0.30	%

Aerospace


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance															As of December 31, 2020
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR(1)		Cumulative Number of Claims
2010 and Prior	$	18,439	$	18,083	$	18,393	$	18,906	$	18,962	$	18,759	$	18,693	$	36	622
2011	58,748		57,226		57,653		58,084		59,578		58,677		58,299		96		2,179
2012	55,293		55,087		55,870		55,823		57,044		56,771		56,907		186		2,375
2013	71,930		69,976		70,255		74,733		77,222		76,774		78,673		297		2,538
2014	65,227		53,457		53,533		52,471		54,534		48,757		45,978		485		2,867
2015			64,550		67,846		70,903		71,624		69,612		69,879		1,070		2,962
2016					35,923		43,371		46,832		43,991		42,954		1,463		2,925
2017							28,816		33,623		54,980		52,590		2,193		3,381
2018									58,573		54,969		54,831		3,491		3,390
2019											45,401		45,784		5,148		2,028
2020													8,732		3,775		357
											Total		$	533,320	$	18,240	25,624
(1) Total of IBNR plus expected development on reported losses
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior	$	15,391	$	16,530	$	17,141	$	18,209	$	18,480	$	18,535	$	18,538
2011	53,785		55,133		55,817		56,394		56,954		57,482		57,483
2012	45,618		49,009		51,787		53,271		54,415		55,160		55,290
2013	50,725		59,639		63,226		68,574		72,573		73,309		73,923
2014	17,297		31,192		38,494		40,749		43,857		43,858		43,868
2015			31,417		50,844		59,342		62,522		64,811		65,630
2016					11,001		30,516		35,884		37,909		37,933
2017							9,000		26,857		44,582		46,134
2018									24,979		39,531		43,284
2019											23,294		30,210
2020													687
											Total		$	472,980
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance													$	60,340

The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below:


	2020
Liabilities for unpaid losses and allocated LAE, net of reinsurance	$	60,340
Reinsurance recoverable on unpaid losses	60,353
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$	120,693

The following is unaudited supplementary information for average annual historical duration of claims:


	Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance
	Year 1		Year 2		Year 3		Year 4		Year 5		Year 6		Year 7		Year 8		Year 9		Year 10
Aerospace	32.80	%	29.84	%	15.40	%	4.61	%	4.31	%	2.22	%	1.93	%	1.12	%	0.48	%	0.01	%

Workers' Compensation


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance															As of December 31, 2020
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR(1)		Cumulative Number of Claims
2010 and Prior	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—	—
2011	—		—		—		—		—		—		—		—		—
2012	—		—		—		—		—		—		—		—		—
2013	—		—		—		—		1		1		1		—		—
2014	10,145		11,179		11,889		10,180		9,867		9,666		9,372		500		137
2015			35,735		36,078		32,567		30,742		29,757		28,768		1,870		259
2016					40,912		35,179		37,703		38,739		36,293		2,847		277
2017							28,188		29,931		22,900		23,320		3,888		295
2018									15,100		14,814		14,490		2,484		161
2019											—		—		—		—
2020													—		—		—
											Total		$	112,244	$	11,589	1,129
(1) Total of IBNR plus expected development on reported losses.
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior	$	—	$	—	$	—	$	—	$	—	$	—	$	—
2011	—		—		—		—		—		—		—
2012	—		—		—		—		—		—		—
2013	—		—		—		—		1		1		1
2014	969,000		3,951		6,031		7,430		7,957		8,201		8,503
2015			4,135		13,126		19,785		22,952		24,301		25,032
2016					5,170		15,229		22,940		27,632		29,539
2017							3,560		10,436		14,600		16,520
2018									2,574		6,431		9,016
2019											—		—
2020													—
											Total		$	88,611
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance													$	23,633

The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below:


	2020
Liabilities for unpaid losses and allocated LAE, net of reinsurance	$	23,633
Reinsurance recoverable on unpaid losses	—
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$	23,633

The following is unaudited supplementary information for average annual historical duration of claims:


	Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance
	Year 1		Year 2		Year 3		Year 4		Year 5		Year 6		Year 7		Year 8		Year 9		Year 10
Workers' compensation	14.40	%	29.38	%	20.46	%	11.77	%	5.19	%	2.57	%	1.61	%	—	%	—	%	—	%

Defendant Asbestos and Environmental Liabilities

12 Months Ended

Dec. 31, 2020

Liability for Asbestos and Environmental Claims [Abstract]

DEFENDANT ASBESTOS AND ENVIRONMENTAL LIABILITIES

11. DEFENDANT ASBESTOS AND ENVIRONMENTAL LIABILITIES

We acquired DCo LLC ("DCo") on December 30, 2016, and Morse TEC on October 30, 2019. These companies hold liabilities associated with personal injury asbestos claims and environmental claims arising from their legacy manufacturing operations. Defendant asbestos liabilities on our consolidated balance sheets include amounts for loss payments and defense costs for pending and future asbestos-related claims, determined using standard actuarial techniques for asbestos exposures. Defendant environmental liabilities include estimated clean-up costs associated with the acquired companies' former operations based on engineering reports.

Insurance balances recoverable on our consolidated balance sheets include estimated insurance recoveries relating to these liabilities. The recorded asset represents our assessment of the capacity of the insurance agreements to indemnify our subsidiaries for the anticipated defense and loss payments for pending claims and projected future claims. The recognition of these recoveries is based on an assessment of the right to recover under the respective contracts and on the financial strength of the insurers. The recorded asset does not represent the limits of our insurance coverage, but rather the amount we would expect to recover if the accrued and projected loss and defense costs were paid in full.

Included within insurance balances recoverable and defendant asbestos and environmental liabilities are the fair value adjustments that were initially recognized upon acquisition. These fair value adjustments are amortized in proportion to the actual payout of claims and recoveries. The carrying value of the asbestos and environmental liabilities, insurance recoveries, future estimated expenses and the fair value adjustments related to DCo and Morse TEC as of December 31, 2020 and 2019 was as follows:


	2020		2019
Defendant asbestos and environmental liabilities:
Defendant asbestos liabilities	$	913,276	$	1,100,593
Defendant environmental liabilities	12,572		10,279
Estimated future expenses	42,510		51,637
Fair value adjustments	(262,029)		(314,824)
Defendant asbestos and environmental liabilities	706,329		847,685

Insurance balances recoverable:
Insurance recoveries related to defendant asbestos liabilities (net of allowance: 2020 - $4,824)	310,602		549,593
Fair value adjustments	(60,950)		(100,738)
Insurance balances recoverable	249,652		448,855

Net liabilities relating to defendant asbestos and environmental exposures	$	456,677	$	398,830

The table below provides a consolidated reconciliation of the beginning and ending liability for defendant asbestos and environmental exposures for the years ended December 31, 2020, 2019 and 2018:


	2020	2019	2018
Balance as of January 1	847,685	203,320	219,164
Less: Insurance balances recoverable	448,855	135,808	122,326
Plus: Cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible insurance balances (1)	3,167	—	—
Net balance as of January 1	401,997	67,512	96,838
Total net recoveries (paid claims)	153,964	(10,434)	(6,351)
Amounts recorded in other income (expense):
Change in estimate of net ultimate liabilities	(103,166)	(4,263)	(23,221)
Reduction in estimated future expenses	(9,126)	(3,274)	—
Amortization of fair value adjustments	13,008	13,500	246
Total other expense (income)	(99,284)	5,963	(22,975)
Acquired on purchase of subsidiaries	—	335,789	—
Net balance as of December 31	456,677	398,830	67,512
Plus: Insurance balances recoverable (2)	249,652	448,855	135,808
Balance as of December 31	706,329	847,685	203,320

(1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 1 - "Significant Accounting Policies" for further details.

(2) Net of allowance for estimated uncollectible insurance balances.

Total other income from our defendant asbestos and environmental liabilities companies was $99.3 million for the year ended December 31, 2020 and was driven by a reduction in the actuarially estimated ultimate net liabilities as a result of a lower than expected number of asbestos claims filed against us; lower than expected paid indemnity and defense costs; the collection of disputed insurance recoveries that were carried on our balance sheet at $166.7 million, net of fair value adjustments, for consideration of $179.6 million; and recovery of $19.3 million on insurance payments previously written-off prior to our acquisition of the companies.

Methodologies for determining liabilities

Defendant Asbestos Liabilities

We review, on an ongoing basis, our own experience in handling asbestos-related claims and trends affecting asbestos-related claims in the U.S. tort system generally, for the purposes of assessing the value of pending asbestos-related claims and the number and value of those that may be asserted in the future, as well as potential recoveries from our insurance carriers with respect to such claims and defense costs. The actuarial analysis for these asbestos-related exposures utilizes data resulting from the claim review process, including input from national coordinating counsel and local counsel, and includes the development of an estimate of the potential value of asbestos-related claims asserted but not yet resolved as well as the number and potential value of asbestos-related claims not yet asserted. In developing the estimate of liability for potential future claims, the actuarial analysis projects the potential number of future claims based on our historical claim filings and epidemiological studies. The actuarial analysis also utilizes assumptions based on our historical proportion of claims resolved without payment, historical claim resolution costs for those claims that result in a payment, and historical defense costs. The liabilities are then estimated by multiplying the pending and projected future claim filings by projected payments rates and average claim resolution amounts and then adding an estimate for defense costs.

We determine, based on the factors described above, including the actuarial analysis, that their best estimate of the aggregate liability both for asbestos-related claims asserted but not yet resolved and potential asbestos-related claims not yet asserted, including estimated defense costs, was $913.3 million and $1.1 billion as of December 31, 2020 and 2019, respectively.

Defendant Environmental Liabilities

As a result of our acquisition of DCo and Morse TEC, we have been identified by the United States Environmental Protection Agency and certain U.S. state environmental agencies and private parties as potentially responsible parties ("PRP") at various hazardous waste disposal sites under the Comprehensive Environmental

Response, Compensation and Liability Act ("Superfund") and equivalent U.S. state laws. The PRPs may currently be liable for the cost of clean-up and other remedial activities at 22 such sites. Responsibility for clean-up and other remedial activities at a Superfund site is typically shared among PRPs based on an allocation formula. We have a liability for defendant environmental liabilities of $12.6 million and $10.3 million as of December 31, 2020 and 2019, respectively. The estimate for defendant environmental liabilities is based on information available to us, including an estimate of the allocation of liability among PRPs, the probability that other PRPs will pay the cost apportioned to them, currently available information from PRPs and/or federal or state environmental agencies concerning the scope of contamination and estimated remediation and consulting costs, and remediation alternatives.

Allowance for Estimated Uncollectible Insurance Balances Recoverable on Defendant Asbestos Liabilities

We evaluate and monitor the credit risk related to our insurers and an allowance for estimated uncollectible insurance balances recoverable on our defendant asbestos liabilities ("allowance for estimated uncollectible insurance") is established for amounts considered potentially uncollectible. To determine the allowance for estimated uncollectible insurance, we use the inputs and methodologies as described in Note 8 - "Reinsurance Balances Recoverable on Paid and Unpaid Losses" above.

The table below provides a reconciliation of the beginning and ending allowance for estimated uncollectible insurance balances related to our defendant asbestos liabilities, for the years ended December 31, 2020 and 2019:


	2020		2019
Allowance for estimated uncollectible insurance balances, beginning of year	$	3,818	$	—
Cumulative effect of change in accounting principle	3,167		—
Current period change in the allowance	(2,161)		3,818


Allowance for estimated uncollectible insurance balances, end of year	$	4,824	$	3,818

During the year ended December 31, 2020, we did not have any write-offs charged against the allowance for estimated uncollectible insurance or any recoveries of amounts previously written off.

We did not have significant non-disputed past due balances receivable from our insurers related to our defendant asbestos liabilities, that were older than one year for any of the periods presented.

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

12. FAIR VALUE MEASUREMENTS

Fair Value Hierarchy

Fair value is defined as the price at which to sell an asset or transfer a liability (i.e. the "exit price") in an orderly transaction between market participants. We use a fair value hierarchy that gives the highest priority to quoted prices in active markets and the lowest priority to unobservable data. The hierarchy is broken down into three levels as follows:

•Level 1 - Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that we have the ability to access. Valuation adjustments and block discounts are not applied to Level 1 instruments.

•Level 2 - Valuations based on quoted prices in active markets for similar assets or liabilities, quoted prices for identical assets or liabilities in inactive markets, or for which significant inputs are observable (e.g. interest rates, yield curves, prepayment speeds, default rates, loss severities, etc.) or can be corroborated by observable market data.

•Level 3 - Valuations based on unobservable inputs where there is little or no market activity. Unadjusted third party pricing sources or management's assumptions and internal valuation models may be used to determine the fair values.

In addition, certain of our other investments are measured at fair value using net asset value ("NAV") per share (or its equivalent) as a practical expedient and have not been classified within the fair value hierarchy above. We have categorized our assets and liabilities that are recorded at fair value on a recurring basis among levels based on the observability of inputs, or at fair value using NAV per share (or its equivalent) as follows:


	December 31, 2020
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value Based on NAV as Practical Expedient		Total Fair Value
Investments:
Short-term and Fixed maturity investments:
U.S. government and agency	$	—	$	951,048	$	—	$	—	$	951,048
U.K. government	—		51,082		—		—		51,082
Other government	—		502,153		—		—		502,153
Corporate	—		5,686,732		—		—		5,686,732
Municipal	—		162,669		—		—		162,669
Residential mortgage-backed	—		553,945		—		—		553,945
Commercial mortgage-backed	—		854,090		—		—		854,090
Asset-backed	—		557,460		—		—		557,460

	$	—	$	9,319,179	$	—	$	—	$	9,319,179

Other assets included within funds held - directly managed	—		14,627		—		—		14,627

Equities:
Publicly traded equity investments	$	229,167	$	31,600	$	—	$	—	$	260,767
Exchange-traded funds	311,287		—		—		—		311,287
Privately held equity investments	—		—		274,741		—		274,741
	$	540,454	$	31,600	$	274,741	$	—	$	846,795

Other investments:

Hedge funds	$	—	$	—	$	—	$	2,638,339	$	2,638,339
Fixed income funds	—		285,837		—		266,704		552,541
Equity funds	—		5,073		—		185,694		190,767
Private equity funds	—		—		—		363,103		363,103

CLO equities	—		128,083		—		—		128,083
CLO equity funds	—		—		—		166,523		166,523
Private credit funds	—		—		9,250		183,069		192,319


Other	—		—		314		12,045		12,359
	$	—	$	418,993	$	9,564	$	3,815,477	$	4,244,034
Total Investments	$	540,454	$	9,784,399	$	284,305	$	3,815,477	$	14,424,635

Cash and cash equivalents	$	385,790	$	208,272	$	—	$	—	$	594,062

Reinsurance balances recoverable on paid and unpaid losses:	$	—	$	—	$	520,830	$	—	$	520,830

Other Assets:
Derivatives qualifying as hedging	$	—	$	1,169	$	—	$	—	$	1,169
Derivatives not qualifying as hedges	—		2,964		—		—		2,964
Derivative instruments	$	—	$	4,133	$	—	$	—	$	4,133

Losses and LAE:	$	—	$	—	$	2,452,920	$	—	$	2,452,920

Other Liabilities:
Derivatives qualifying as hedging	$	—	$	28,947	$	—	$	—	$	28,947
Derivatives not qualifying as hedges	—		5,195		—		—		5,195
Derivative instruments	$	—	$	34,142	$	—	$	—	$	34,142


	December 31, 2019
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value Based on NAV as Practical Expedient		Total Fair Value
Investments:
Short-term and Fixed maturity investments:
U.S. government and agency	$	—	$	696,077	$	—	$	—	$	696,077
U.K government	—		161,772		—		—		161,772
Other government	—		702,856		—		—		702,856
Corporate	—		5,448,270		—		—		5,448,270
Municipal	—		140,687		—		—		140,687
Residential mortgage-backed	—		400,914		—		—		400,914
Commercial mortgage-backed	—		813,746		—		—		813,746
Asset-backed	—		670,235		—		—		670,235
	$	—	$	9,034,557	$	—	$	—	$	9,034,557

Other assets included within funds held - directly managed	$	—	$	14,207	$	—	$	—	$	14,207

Equities:
Publicly traded equity investments	$	297,310	$	30,565	$	—	$	—	$	327,875
Exchange-traded funds	133,047		—		—		—		133,047
Privately held equity investments	—		—		265,799		—		265,799
	$	430,357	$	30,565	$	265,799	$	—	$	726,721

Other investments:
Hedge funds	$	—	$	—	$	—	$	1,121,904	$	1,121,904
Fixed income funds	—		398,143		—		82,896		481,039
Equity funds	—		111,040		—		299,109		410,149
Private equity funds	—		—		—		323,496		323,496
CLO equities	—		—		87,555		—		87,555
CLO equity funds	—		—		—		87,509		87,509

Other	—		34		314		6,031		6,379
	$	—	$	509,217	$	87,869	$	1,920,945	$	2,518,031
Total Investments	$	430,357	$	9,588,546	$	353,668	$	1,920,945	$	12,293,516

Cash and cash equivalents	$	144,984	$	222,191	$	—	$	—	$	367,175

Reinsurance balances recoverable on paid and unpaid losses:	$	—	$	—	$	695,518	$	—	$	695,518

Other Assets:
Derivatives qualifying as hedging	$	—	$	642	$	—	$	—	$	642
Derivatives not qualifying as hedges	—		1,369		—		—		1,369
Derivative instruments	$	—	$	2,011	$	—	$	—	$	2,011

Losses and LAE:	$	—	$	—	$	2,621,122	$	—	$	2,621,122

Other Liabilities:
Derivatives qualifying as hedging	$	—	$	11,452	$	—	$	—	$	11,452
Derivatives not qualifying as hedges	—		4,106		—		—		4,106
Derivative instruments	$	—	$	15,558	$	—	$	—	$	15,558

Valuation Methodologies of Financial Instruments Measured at Fair Value

Short-term and Fixed Maturity Investments

The fair values for all securities in the short-term and fixed maturity investments and funds held - directly managed portfolios are independently provided by the investment accounting service providers, investment managers and investment custodians, each of which utilize internationally recognized independent pricing services. We record the unadjusted price provided by the investment accounting service providers, investment managers or investment custodians and validate this price through a process that includes, but is not limited to: (i) comparison of prices against alternative pricing sources; (ii) quantitative analysis (e.g. comparing the quarterly return for each managed portfolio to its target benchmark); (iii) evaluation of methodologies used by external parties to estimate fair value, including a review of the inputs used for pricing; and (iv) comparing the price to our knowledge of the current investment market. Our internal price validation procedures and review of fair value methodology documentation provided by independent pricing services have not historically resulted in adjustment in the prices obtained from the pricing service.

The independent pricing services used by the investment accounting service providers, investment managers and investment custodians obtain actual transaction prices for securities that have quoted prices in active markets. Where we utilize single unadjusted broker-dealer quotes, they are generally provided by market makers or broker-dealers who are recognized as market participants in the markets for which they are providing the quotes. For determining the fair value of securities that are not actively traded, in general, pricing services use "matrix pricing" in which the independent pricing service uses observable market inputs including, but not limited to, reported trades, benchmark yields, broker-dealer quotes, interest rates, prepayment speeds, default rates and other such inputs as are available from market sources to determine a reasonable fair value.

The following describes the techniques generally used to determine the fair value of our short-term and fixed maturity investments by asset class, including the investments underlying the funds held - directly managed.

•U.S. government and agency securities consist of securities issued by the U.S. Treasury and mortgage pass-through agencies such as the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation and other agencies. Non-U.S. government securities consist of bonds issued by non-U.S. governments and agencies along with supranational organizations. The significant inputs used to determine the fair value of these securities include the spread above the risk-free yield curve, reported trades and broker-dealer quotes. These are considered to be observable market inputs and, therefore, the fair values of these securities are classified as Level 2.

•Corporate securities consist primarily of investment-grade debt of a wide variety of corporate issuers and industries. The fair values of these securities are determined using the spread above the risk-free yield curve, reported trades, broker-dealer quotes, benchmark yields, and industry and market indicators. These are considered observable market inputs and, therefore, the fair values of these securities are classified as Level 2. Where pricing is unavailable from pricing services, such as in periods of low trading activity or when transactions are not orderly, we obtain non-binding quotes from broker-dealers. Where significant inputs are unable to be corroborated with market observable information, we classify the securities as Level 3.

•Municipal securities consist primarily of bonds issued by U.S.-domiciled state and municipal entities. The fair values of these securities are determined using the spread above the risk-free yield curve, reported trades, broker-dealer quotes and benchmark yields. These are considered observable market inputs and, therefore, the fair values of these securities are classified as Level 2.

•Asset-backed securities consist primarily of investment-grade bonds backed by pools of loans with a variety of underlying collateral. Residential and commercial mortgage-backed securities include both agency and non-agency originated securities. Where pricing is unavailable from pricing services, we obtain non-binding quotes from broker-dealers. This is generally the case when there is a low volume of trading activity and current transactions are not orderly. The significant inputs used to determine the fair value of these securities include the spread above the risk-free yield curve, reported trades, benchmark yields, prepayment speeds and default rates. The fair values of these securities are classified as Level 2 if the significant inputs are market observable. Where significant inputs are unable to be corroborated with market observable information, we classify the securities as Level 3.

Equities

Our investments in equities consist of a combination of publicly and privately traded investments. Our publicly traded equity investments in common and preferred stocks predominantly trade on major exchanges and are managed by our external advisors. Our exchange-traded funds also trade on major exchanges. Our publicly traded equities are widely diversified and there is no significant concentration in any specific industry. We use an internationally recognized pricing service to estimate the fair value of our publicly traded equities and exchange-traded funds. We have categorized the majority of our publicly traded equity investments, other than preferred stock, and our exchange-traded funds as Level 1 investments because the fair values of these investments are based on unadjusted quoted prices in active markets for identical assets. One equity security is trading in an inactive market and, as a result has been classified as Level 2. The fair value estimates of our investments in publicly traded preferred stock are based on observable market data and, as a result, have been categorized as Level 2.

Our privately held equity investments in common and preferred stocks are direct investments in companies that we believe offer attractive risk adjusted returns and/or offer other strategic advantages. Each investment may have its own unique terms and conditions and there may be restrictions on disposals. The market for these investments is illiquid and there is no active market. We use a combination of cost, internal models, reported values from co-investors/managers and observable inputs, such as capital raises and capital transactions between new and existing shareholders to calculate the fair value of the privately held equity investments. The fair value estimates of our investments in privately held equities are based on unobservable market data and, as a result, have been categorized as Level 3.

Other investments, at fair value

We have ongoing due diligence processes with respect to the other investments carried at fair value in which we invest, including active discussions with managers of the investments. These processes are designed to assist us in assessing the quality of information provided by, or on behalf of, each fund and in determining whether such information continues to be reliable or whether further review is warranted. Certain funds do not provide full transparency of their underlying holdings; however, we obtain the audited financial statements for funds annually and review the audited results relative to the net asset values provided by the managers, and regularly review and discuss the fund performance with the fund managers to corroborate the reasonableness of the reported net asset values ("NAV").

The use of NAV as an estimate of the fair value for investments in certain entities that calculate NAV is a permitted practical expedient. Due to the time lag in the NAV reported by certain fund managers we adjust the valuation for capital calls and distributions. Other investments measured at fair value using NAV as a practical expedient have not been classified in the fair value hierarchy. Other investments for which we do not use NAV as a practical expedient have been valued using prices from independent pricing services, investment managers and broker-dealers.

The following describes the techniques generally used to determine the fair value of our other investments.

•For our investments in hedge funds, we measure fair value by obtaining the most recently available NAV as advised by the external fund manager or third-party administrator. The fair values of these investments are measured using the NAV as a practical expedient and therefore have not been categorized within the fair value hierarchy.

•Our investments in fixed income funds and equity funds are valued based on a combination of prices from independent pricing services, external fund managers or third-party administrators. For the publicly available prices we have classified the investments as Level 2. For the non-publicly available prices we are using NAV as a practical expedient and therefore these have not been categorized within the fair value hierarchy.

•For our investments in private equity funds, we measure fair value by obtaining the most recently available NAV from the external fund manager or third-party administrator. The fair values of these investments are measured using the NAV as a practical expedient and therefore have not been categorized within the fair value hierarchy.

•We measure the fair value of our direct investment in CLO equities based on valuations provided by independent pricing services, our external CLO equity manager, and valuations provided by the broker or lead underwriter of the investment (the "broker"). The fair values measured using prices provided by independent pricing services have been classified as Level 2 and fair values using prices from brokers have

been classified as Level 3 due to the use of unobservable inputs in the valuation and the limited number of relevant trades in secondary markets.

•For our investments in the CLO equity funds, we measure fair value by obtaining the most recently available NAV as advised by the external fund manager or third party administrator. The fair value of these investments is measured using the NAV as a practical expedient and therefore have not been categorized within the fair value hierarchy.

•Our investments in private credit funds are primarily valued by obtaining the most recently available NAV from the external fund manager or third-party administrator. The fair values of these investments are measured using the NAV as a practical expedient and therefore have not been categorized within the fair value hierarchy. Included within private credit funds is a loan which is valued at cost less distributions received to date.

•Included within other is an investment in a real estate debt fund, for which we measure fair value by obtaining the most recently available NAV from the external fund manager or third-party administrator. The fair value of this investment is measured using the NAV as a practical expedient and therefore has not been categorized within the fair value hierarchy.

Cash and Cash Equivalents

Cash equivalents are short-term, highly liquid investments that are readily convertible to known amounts of cash and are very close to maturity that they present insignificant risk of changes in value due to changes in interest rates. Included within cash and cash equivalents are money market funds, fixed interest deposits and highly liquid fixed maturity investments purchased with an original maturity of three months or less.

The majority of our cash and cash equivalents included within the fair value hierarchy are comprised of money market and liquid reserve funds which have been categorized as Level 1. Fixed interest deposits and highly liquid fixed maturity investments with an original maturity of three months or less have been categorized as Level 2. Operating cash balances are not subject to the recurring fair value measurement guidance and are therefore excluded from the fair value hierarchy.

Insurance Contracts - Fair Value Option

The Company uses an internal model to calculate the fair value of the liability for losses and loss adjustment expenses and reinsurance balances recoverable on paid and unpaid losses for certain retroactive reinsurance contracts where we have elected the fair value option in our Non-life Run-off segment. The fair value was calculated as the aggregate of discounted cash flows plus a risk margin. The discounted cash flow approach uses (i) estimated nominal cash flows based upon an appropriate payment pattern developed in accordance with standard actuarial techniques and (ii) a discount rate based upon a high quality rated corporate bond yield plus a credit spread for non-performance risk. The model uses corporate bond rates across the yield curve depending on the estimated timing of the future cash flows and specific to the currency of the risk. The risk margin was calculated using the present value of the cost of capital. The cost of capital approach uses (i) projected capital requirements, (ii) multiplied by the risk cost of capital representing the return required for non-hedgeable risk based upon the weighted average cost of capital less investment income and (iii) discounted using the weighted average cost of capital.

Derivative Instruments

The fair values of our derivative instruments, as described in Note 7 - "Derivatives and Hedging Instruments," are classified as Level 2. The fair values are based upon prices in active markets for identical contracts.

Level 3 Measurements and Changes in Leveling

Transfers into or out of levels are recorded at their fair values as of the end of the reporting period, consistent with the date of determination of fair value.

Investments

The following tables present a reconciliation of the beginning and ending balances for all investments measured at fair value on a recurring basis using Level 3 inputs during the years ended December 31, 2020 and 2019:


				2020
	Privately-held Equities	Other Investments	Total

Beginning fair value				$	265,799	$	87,869	$	353,668
Purchases				20,125		47,092		67,217
Sales				—		(1,289)		(1,289)
Total realized and unrealized losses				(11,183)		(40,368)		(51,551)

Transfer out of Level 3 into Level 2				—		(83,740)		(83,740)
Ending fair value				$	274,741	$	9,564	$	284,305


	2019
	Fixed maturity investments								Privately-held Equities		Other Investments		Total
	Corporate		Residential mortgage-backed		Commercial mortgage-backed		Asset-backed
Beginning fair value	$	37,386	$	—	$	7,389	$	9,121	$	228,710	$	39,367	$	321,973
Purchases	184		—		—		—		30,713		56,908		87,805
Sales	(3,520)		—		(784)		(3,605)		(2,016)		(590)		(10,515)
Total realized and unrealized gains (losses)	90		(1)		64		255		8,392		(7,816)		984
Transfer into Level 3 from Level 2	3,535		102		1,515		21,024		—		—		26,176
Transfer out of Level 3 into Level 2	(37,675)		(101)		(8,184)		(26,795)		—		—		(72,755)
Ending fair value	$	—	$	—	$	—	$	—	$	265,799	$	87,869	$	353,668

Net realized and unrealized gains related to Level 3 assets in the table above are included in net realized and unrealized gains (losses) in our consolidated statements of earnings.

The securities transferred from Level 2 to Level 3 were transferred due to insufficient market observable inputs for the valuation of the specific assets. The transfers from Level 3 to Level 2 were based upon obtaining market observable information regarding the valuations of the specific assets.

Valuations Techniques and Inputs

The table below presents the quantitative information related to the fair value measurements for our privately held equity investments measured at fair value on a recurring basis using Level 3 inputs:


		Quantitative Information about Level 3 Fair Value Measurements
		Fair Value as of December 31, 2020			Valuation Techniques		Unobservable Input	Average (1)
		(in millions of U.S. dollars)


		$	230.3		Guideline company methodology		Distribution waterfall	12.98
$	54.0			Cost as approximation of fair value		Cost as approximation of fair value
$	284.3

(1) The average represents the arithmetic average of the inputs and is not weighted by the relative fair value.

Insurance Contracts - Fair Value Option

The following table presents a reconciliation of the beginning and ending balances for all insurance contracts measured at fair value on a recurring basis using Level 3 inputs during the years ended December 31, 2020 and 2019:


	2020						2019
	Liability for losses and LAE		Reinsurance balances recoverable on paid and unpaid losses		Net		Liability for losses and LAE		Reinsurance balances recoverable on paid and unpaid losses		Net
Beginning fair value	$	2,621,122	$	695,518	$	1,925,604	$	2,874,055	$	739,591	$	2,134,464
Assumed business	1,526		(180,972)		182,498		9,218		—		9,218
Incurred losses and LAE:
Reduction in estimates of ultimate losses	(73,596)		59,478		(133,074)		(32,690)		(2,958)		(29,732)
Reduction in unallocated LAE	(17,484)		—		(17,484)		(19,915)		—		(19,915)
Change in fair value	157,965		38,919		119,046		160,630		43,449		117,181
Total incurred losses and LAE	66,885		98,397		(31,512)		108,025		40,491		67,534
Paid losses	(300,234)		(101,326)		(198,908)		(416,770)		(92,145)		(324,625)
Effect of exchange rate movements	63,621		9,213		54,408		46,594		7,581		39,013
Ending fair value	$	2,452,920	$	520,830	$	1,932,090	$	2,621,122	$	695,518	$	1,925,604

The net assumed business of $182.5 million in the current period relates to the Hannover Re novation transaction disclosed in Note 4 - "Significant New Business." Changes in fair value in the table above are included in net incurred losses and LAE in our consolidated statements of earnings.

The following table presents the components of the net change in fair value for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Changes in fair value due to changes in:
Duration	$	20,861	$	22,719	$	74,011
Corporate bond yield	96,478		94,462		(71,031)

Weighted cost of capital	(5,048)		—
Risk cost of capital	6,755		—		3,684
Change in fair value	$	119,046	$	117,181	$	6,664

Below is a summary of the quantitative information regarding the significant observable and unobservable inputs used in the internal model to determine fair value on a recurring basis as of December 31, 2020 and 2019:

2020

2019

Valuation Technique

Unobservable (U) and Observable (O) Inputs

Weighted Average

Internal model

Corporate bond yield (O)

A rated

Internal model

Credit spread for non-performance risk (U)

0.2%

Internal model

Risk cost of capital (U)

5.1%

Internal model

Weighted average cost of capital (U)

8.25%

8.5%

Internal model

Duration - liability (U)

8.17 years

7.82 years

Internal model

Duration - reinsurance balances recoverable on paid and unpaid losses (U)

8.23 years

8.68 years

The fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses may increase or decrease due to changes in the corporate bond rate, the credit spread for non-performance risk, the risk cost of capital, the weighted average cost of capital and the estimated payment pattern as described

below:

•An increase in the corporate bond rate or credit spread for non-performance risk would result in a decrease in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses. Conversely, a decrease in the corporate bond rate or credit spread for non-performance risk would result in an increase in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses.

•An increase in the weighted average cost of capital would result in an increase in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses. Conversely, a decrease in the weighted average cost of capital would result in a decrease in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses.

•An increase in the risk cost of capital would result in an increase in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses. Conversely, a decrease in the risk cost of capital would result in a decrease in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses.

•The duration of the liability and recoverable is adjusted every period to reflect actual net payments during the period and expected future payments. An acceleration of the estimated payment pattern, a decrease in duration, would result in an increase in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses. Conversely, a deceleration of the estimated payment pattern, an increase in duration, would result in a decrease in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses.

In addition, the estimate of the capital required to support the liabilities is based upon current industry standards for capital adequacy. If the required capital per unit of risk increases, then the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses would increase. Conversely, a decrease in required capital would result in a decrease in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses.

Disclosure of Fair Values for Financial Instruments Carried at Cost

Senior Notes

As of December 31, 2020, our 4.50% Senior Notes due 2022 (the "2022 Senior Notes") and our 4.95% Senior Notes due 2029 (the "2029 Senior Notes" and, together with the 2022 Senior Notes, the "Senior Notes") were carried at amortized cost of $349.3 million and $494.2 million, respectively, while the fair value based on observable market pricing from a third party pricing service was $362.4 million and $573.3 million, respectively. The Senior Notes are classified as Level 2.

Junior Subordinated Notes

As of December 31, 2020, our 5.75% Fixed-Rate Reset Junior Subordinated Notes due 2040 (the “Junior Subordinated Notes”) were carried at amortized cost of $344.8 million, while the fair value based on observable market pricing from a third party pricing service was $365.7 million. The Junior Subordinated Notes are classified as Level 2.

Insurance Contracts

Disclosure of fair value of amounts relating to insurance contracts is not required, except those for which we elected the fair value option, as described above.

Remaining Assets and Liabilities

Our remaining assets and liabilities were generally carried at cost or amortized cost, which due to their short-term nature approximates fair value as of December 31, 2020 and 2019.

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

Premiums Written and Earned

12 Months Ended

Dec. 31, 2020

PREMIUMS WRITTEN AND EARNED

8. REINSURANCE BALANCES RECOVERABLE ON PAID AND UNPAID LOSSES

The following tables provide the total reinsurance balances recoverable on paid and unpaid losses.


	December 31, 2020
	Non-life Run-off		StarStone		Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	938,231	$	263,638	$	1,201,869
IBNR	508,082		139,761		647,843
ULAE	16,688		—		16,688
Fair value adjustments - acquired companies	(14,014)		(1,339)		(15,353)
Fair value adjustments - fair value option	(21,427)		—		(21,427)
Total reinsurance reserves recoverable	1,427,560		402,060		1,829,620
Paid losses recoverable	172,309		87,234		259,543
Total	$	1,599,869	$	489,294	$	2,089,163

Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable on paid and unpaid losses	$	1,079,039	$	489,294	$	1,568,333
Reinsurance balances recoverable on paid and unpaid losses - fair value option	520,830		—		520,830
Total	$	1,599,869	$	489,294	$	2,089,163


	December 31, 2019
	Non-life Run-off		Atrium		StarStone		Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	972,293	$	9,011	$	264,131	$	1,245,435
IBNR	673,059		19,286		93,185		785,530

Fair value adjustments - acquired companies	(13,652)		519		(2,122)		(15,255)
Fair value adjustments - fair value option	(88,086)		—		—		(88,086)
Total reinsurance reserves recoverable	1,543,614		28,816		355,194		1,927,624
Paid losses recoverable	181,375		1,541		70,594		253,510
Total	$	1,724,989	$	30,357	$	425,788	$	2,181,134

Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable on paid and unpaid losses	$	1,029,471	$	30,357	$	425,788	$	1,485,616
Reinsurance balances recoverable on paid and unpaid losses - fair value option	695,518		—		—		695,518
Total	$	1,724,989	$	30,357	$	425,788	$	2,181,134

reinsurance contracts for which we have elected the fair value option is described in Note 12 - "Fair Value Measurements".

Top Ten Reinsurers


	December 31, 2020
	Non-life Run-off		StarStone		Total		% of Total
Top 10 reinsurers	$	1,036,676	$	327,917	$	1,364,593	65.3	%
Other reinsurers > $1 million	539,428		158,174		697,602		33.4	%
Other reinsurers < $1 million	23,765		3,203		26,968		1.3	%
Total	$	1,599,869	$	489,294	$	2,089,163	100.0	%


	December 31, 2019
	Non-life Run-off		Atrium		StarStone		Total		% of Total
Top 10 reinsurers	$	1,154,110	$	22,051	$	295,443	$	1,471,604	67.4	%
Other reinsurers > $1 million	551,636		7,761		129,335		688,732		31.6	%
Other reinsurers < $1 million	19,243		545		1,010		20,798		1.0	%
Total	$	1,724,989	$	30,357	$	425,788	$	2,181,134	100.0	%


	December 31, 2020		December 31, 2019
Information regarding top ten reinsurers:
Number of top 10 reinsurers rated A- or better	7		8
Number of top 10 non-rated reinsurers (1)	3		2

Reinsurers rated A- or better in top 10	$	863,819	$	1,199,479
Non-rated reinsurers in top 10 (1)	500,774		272,125
Total top 10 reinsurance recoverables	$	1,364,593	$	1,471,604

Single reinsurers that represent 10% or more of total reinsurance balance recoverables as of December 31, 2020 and 2019:

Hannover Ruck SE (2)	$	—	$	259,077
Lloyd's Syndicates (3)	$	331,118	$	396,246
Michigan Catastrophic Claims Association(4)	$	229,374	$	—

(1) The reinsurance balances recoverable from the three and two non-rated top 10 reinsurers as of December 31, 2020 and 2019, respectively, was comprised of:

(3) Lloyd's Syndicates are rated A+ by Standard & Poor's and A by A.M. Best.

(4) U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state.

Allowance for Estimated Uncollectible Reinsurance Balances Recoverable on Paid and Unpaid Losses


	December 31, 2020
	Gross		Allowance for estimated uncollectible reinsurance		Net		Provisions as a % of Gross
Reinsurers rated A- or above	$	1,464,529	$	60,801	$	1,403,728	4.2	%
Reinsurers rated below A-, secured	608,999		—		608,999		—	%
Reinsurers rated below A-, unsecured	152,757		76,321		76,436		50.0	%
Total	$	2,226,285	$	137,122	$	2,089,163	6.2	%


	December 31, 2019
	Gross		Allowance for estimated uncollectible reinsurance		Net		Provisions as a % of Gross
Reinsurers rated A- or above	$	1,731,270	$	43,427	$	1,687,843	2.5	%
Reinsurers rated below A-, secured	463,840		—		463,840		—	%
Reinsurers rated below A-, unsecured	133,663		104,212		29,451		78.0	%
Total	$	2,328,773	$	147,639	$	2,181,134	6.3	%

The table below provides a reconciliation of the beginning and ending allowance for estimated uncollectible reinsurance balances for the years ended December 31, 2020 and 2019:


	2020		2019
Allowance for estimated uncollectible reinsurance, beginning of year	$	147,639	$	156,732
Cumulative effect of change in accounting principle	(195)		—
Effect of exchange rate movement	700		(887)
Current period change in the allowance	(381)		2,077
Write-offs charged against the allowance	(9,625)		(9,871)
Recoveries collected	(1,016)		(412)
Allowance for estimated uncollectible reinsurance, end of year	$	137,122	$	147,639

13. PREMIUMS WRITTEN AND EARNED

The following tables provide a summary of net premiums written and earned for the years ended December 31, 2020, 2019 and 2018:


	2020				2019				2018
	Premiums Written		Premiums Earned		Premiums Written		Premiums Earned		Premiums Written		Premiums Earned
Non-life Run-off
Gross	$	5,191	$	71,522	$	(25,069)	$	197,009	$	(8,910)	$	25,230
Ceded	(2,204)		(12,827)		(269)		(28,513)		(307)		(15,803)
Net	$	2,987	$	58,695	$	(25,338)	$	168,496	$	(9,217)	$	9,427
Atrium
Gross	$	206,656	$	197,492	$	192,373	$	182,678	$	171,494	$	164,428
Ceded	(23,462)		(22,099)		(20,017)		(18,619)		(18,006)		(18,113)
Net	$	183,194	$	175,393	$	172,356	$	164,059	$	153,488	$	146,315
StarStone
Gross	$	326,695	$	441,015	$	472,815	$	549,299	$	622,570	$	647,218
Ceded	(93,493)		(122,900)		(93,292)		(98,187)		(144,561)		(132,055)
Net	$	233,202	$	318,115	$	379,523	$	451,112	$	478,009	$	515,163
Other
Gross	$	13,441	$	19,889	$	18,534	$	20,544	$	32,378	$	25,237
Ceded	—		—		(22)		(164)		(311)		(363)
Net	$	13,441	$	19,889	$	18,512	$	20,380	$	32,067	$	24,874
Total
Gross	$	551,983	$	729,918	$	658,653	$	949,530	$	817,532	$	862,113
Ceded	(119,159)		(157,826)		(113,600)		(145,483)		(163,185)		(166,334)
Net	$	432,824	$	572,092	$	545,053	$	804,047	$	654,347	$	695,779

Goodwill and Intangible Assets

12 Months Ended

Dec. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Intangible Assets

14. GOODWILL AND INTANGIBLE ASSETS

The following table presents a reconciliation of the beginning and ending goodwill and intangible assets, included within other assets in the consolidated balance sheets, for the years ended December 31, 2020 and 2019:


	Goodwill		Intangible assets with a definite life		Intangible assets with an indefinite life		Total
Balance as of December 31, 2018	$	109,807	$	16,887	$	67,131	$	193,825

Amortization	—		(2,257)		—		(2,257)
Balance as of December 31, 2019	$	109,807	$	14,630	$	67,131	$	191,568

Amortization	—		(1,524)		—		(1,524)
Impairment losses (StarStone International) (1)	(8,000)		—		(4,000)		(12,000)
Reclassification to assets held-for-sale (Atrium) (2)	(38,848)		(13,106)		(63,131)		(115,085)
Balance as of December 31, 2020	$	62,959	$	—	$	—	$	62,959

(1) On June 10, 2020, we announced the StarStone International Run-Off. During the year ended December 31, 2020, we recognized impairment losses of $8.0 million related to the goodwill allocated to StarStone International and $4.0 million on StarStone's Lloyd's syndicate capacity.

(2) On August 13, 2020, we announced the Atrium Exchange Transaction, which resulted in the assets and liabilities of the Atrium segment being classified as held-for-sale as of December 31, 2020. Refer to Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations" for further information.

The gross carrying value, accumulated amortization and net carrying value of goodwill and intangible assets by segment and by type as of December 31, 2020 and 2019 was as follows:


	December 31, 2020						December 31, 2019
	Gross carrying value		Accumulated amortization		Net carrying value		Gross carrying value		Accumulated amortization		Net carrying value
Non-life Run-off segment:
Goodwill	$	62,959	$	—	$	62,959	$	62,959	$	—	$	62,959

Atrium segment:
Goodwill	—		—		—		38,848		—		38,848
Intangible assets with a definite life:
Distribution channel	—		—		—		20,000		(8,111)		11,889
Brand	—		—		—		7,000		(4,259)		2,741
Intangible assets with an indefinite life:
Lloyd’s syndicate capacity	—		—		—		33,031		—		33,031
Management contract	—		—		—		30,100		—		30,100
Total Atrium segment goodwill and intangible assets	—		—		—		128,979		(12,370)		116,609

StarStone segment:
Goodwill	—		—		—		8,000		—		8,000
Intangible assets with an indefinite life:
Lloyd’s syndicate capacity	—		—		—		4,000		—		4,000
Total StarStone segment goodwill and intangible assets	—		—		—		12,000		—		12,000
Total goodwill and intangible assets	$	62,959	$	—	$	62,959	$	203,938	$	(12,370)	$	191,568

The amortization recorded on the intangible assets of the Atrium segment, prior to the reclassification to held-for-sale, for the years ended December 31, 2020, 2019 and 2018 was $1.5 million, $2.3 million and $3.6 million, respectively.

Debt Obligations and Credit Facilities

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Debt Obligations and Credit Facilities

15. DEBT OBLIGATIONS AND CREDIT FACILITIES

We utilize debt and credit facilities primarily for funding acquisitions and significant new business, investment activities and, from time to time, for general corporate purposes. Our debt obligations were as follows:


Facility	Origination Date	Term	December 31, 2020		December 31, 2019
4.50% Senior Notes due 2022	March 10, 2017	5 years	$	349,253	$	348,616
4.95% Senior Notes due 2029	May 28, 2019	10 years	494,194		493,600
Total Senior Notes			843,447		842,216
5.75% Junior Subordinated Notes due 2040	August 26, 2020	20 years	344,812		—
EGL Revolving Credit Facility	August 16, 2018	5 years	185,000		—
2018 EGL Term Loan Facility	December 27, 2018	3 years	—		348,991
Total debt obligations			$	1,373,259	$	1,191,207

In 2020, we issued the Junior Subordinated Notes and fully repaid the 2018 EGL Term Loan Facility.

The table below provides a summary of the total interest expense for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Interest expense on debt obligations	$	57,974	$	51,245	$	25,205
Amortization of debt issuance costs	1,331		953		537


Funds withheld balances and other	3		343		(46)
Total interest expense	$	59,308	$	52,541	$	25,696

Senior Notes

We have issued two series of Senior Notes as shown in the table above. The Senior Notes are effectively subordinated to any of our secured indebtedness to the extent of the value of the assets securing such indebtedness, and structurally subordinated to all liabilities of our subsidiaries, including claims of policyholders. The 2022 Senior Notes and the 2029 Senior Notes bear interest at a fixed rate per annum, equal to 4.50% and 4.95%, respectively.

Both series of Senior Notes are rated BBB-. We may repurchase the 2029 Senior Notes at any time prior to three months prior to maturity of the 2029 Senior Notes, subject to the payment of a make-whole premium. After such date, we may repurchase the 2029 Senior Notes at a purchase price equal to 100% of the outstanding principal amount, plus accrued and unpaid interest. We do not have the right to repurchase the 2022 Senior Notes prior to their maturity.

We incurred costs of $2.9 million and $6.8 million in issuing the 2022 and 2029 Senior Notes, respectively. The unamortized costs as of December 31, 2020 were $0.7 million and $5.8 million, respectively.

Junior Subordinated Notes

5.75% Junior Subordinated Notes due 2040

On August 26, 2020, our wholly-owned subsidiary, Enstar Finance LLC ("Enstar Finance") issued the Junior Subordinated Notes in an aggregate principal amount of $350.0 million. The Junior Subordinated Notes bear interest (i) during the initial five-year period ending August 30, 2025, at a fixed rate per annual of 5.75% and (ii) during each five-year reset period thereafter beginning September 1, 2025, at a fixed rate per annum equal to the five-year U.S. treasury rate calculated as of two business days prior to the beginning of such five-year period plus 5.468%.

The Junior Subordinated Notes are rated BB+ and are unsecured junior subordinated obligations of Enstar Finance. The Junior Subordinated Notes are fully and unconditionally guaranteed by us on an unsecured and junior subordinated basis. These debt securities of Enstar Finance are effectively subordinated to the obligations of our other subsidiaries.

Subject to certain requirements and during certain time periods, Enstar Finance may repurchase the Junior Subordinated Notes, in whole or in part, at any time, at a repurchase price equal to at least 100% of the principal amount, plus accrued and unpaid interest.

We incurred costs of $5.2 million in issuing the Junior Subordinated Notes. The unamortized costs as of December 31, 2020 were $5.2 million.

EGL Revolving Credit Facility

On August 16, 2018, we entered into a five-year, unsecured $600.0 million revolving credit agreement. We may request additional commitments under the facility up to an additional $400.0 million, which the existing lenders in their discretion or new lenders may provide, in each case subject to the terms of the agreement. To date, we have not requested any additional commitments under the facility.

As of December 31, 2020, we were permitted to borrow up to an aggregate of $600.0 million under the revolving credit facility. As of December 31, 2020, there was $415.0 million of available unutilized capacity under the facility. Subsequent to December 31, 2020, we borrowed an additional $20.0 million and repaid $30.0 million, increasing the unutilized capacity under the facility to $425.0 million.

We pay interest on loans borrowed under the facility at a per annum rate comprising a reference rate determined based on the type of loan we borrow plus a margin based on the Company's long term senior unsecured debt ratings. The applicable reference rate is adjusted base rate for base rate loans and adjusted LIBOR

for LIBOR loans. The applicable margin varies based upon changes to our long term senior unsecured debt ratings assigned by S&P or Fitch. We pay interest quarterly for base rate loans and as frequently as monthly for LIBOR loans, depending on the applicable interest period. We also pay a commitment fee based on the average daily unutilized capacity under the facility. If an event of default occurs, the interest rate may increase and the agent may, and at the request of the required lenders shall, terminate lender commitments and demand early repayment of any outstanding loans borrowed under the facility.We are subject to business and financial covenants under the revolving credit agreement. Business covenants include limitations on indebtedness and guarantees; liens; mergers, consolidations and other fundamental changes; dispositions; and investments and acquisitions, in each case subject to certain exceptions. Generally, the financial covenants require us to maintain a gearing ratio of consolidated indebtedness to total capitalization of not greater than 0.35 to 1.0 and to maintain a consolidated net worth of not less than the aggregate of (i) $2.3 billion, (ii) 50% of net income available for distribution to our ordinary shareholders at any time after August 16, 2018, and (iii) 50% of the proceeds of any common stock issuance made after August 16, 2018. In addition, we must maintain eligible capital in excess of the enhanced capital requirement imposed on us by the Bermuda Monetary Authority pursuant to the Insurance (Group Supervision) Rules 2011 of Bermuda. We are in compliance with the covenants of the

2018 EGL Term Loan Facility

On December 27, 2018, we entered into and fully utilized a three-year, unsecured $500.0 million term loan. During 2019, we repaid $150.0 million, and during 2020, we repaid the remaining $350.0 million and terminated the facility.

Maturities

As of December 31, 2020, the amount of outstanding debt obligations that will become due in each of the next five years and thereafter was as follows: 2021, $0; 2022, $350.0 million; 2023, $185.0 million; 2024, $0; and thereafter, $850.0 million.

Letters of Credit

We utilize unsecured and secured letters of credit to support certain of our (re)insurance performance obligations.

$275.0 million Funds at Lloyd's Letter of Credit Facility

On November 5, 2020, we amended and restated our Fund's at Lloyd's letter of credit facility to reduce its capacity to $275.0 million (with the right to request additional commitments under the facility in an aggregate amount not to exceed $75.0 million) and extended its term by two years. We use letters of credit under this facility to satisfy a portion of our Funds at Lloyd's requirements, and letters of credit issued under the facility will expire at the end of 2025. As of December 31, 2020 and December 31, 2019, our combined Funds at Lloyd's comprised cash and investments of $260.9 million and $639.3 million, respectively, and unsecured letters of credit of $210.0 million and $252.0 million, respectively.

$120.0 million Letter of Credit Facility

We use this facility to provide collateral support for certain reinsurance obligations of our subsidiaries. We may request additional commitments under the facility in an aggregate amount not to exceed $60.0 million, which the existing lender in its discretion or new lenders may provide, in each case subject to the terms of the agreement. As of December 31, 2020 and December 31, 2019, The aggregate amount of letters of credit issued under the facility was $115.7 million and $115.3 million, respectively.

$800.0 million Syndicated Letter of Credit Facility

On August 4, 2020, we increased the total commitments available under this facility by an aggregate amount of $40.0 million, bringing the total size of the facility to $800.0 million. We use this facility to collateralize certain reinsurance obligations. As of December 31, 2020 and December 31, 2019, the aggregate amount of letters of credit issued under the facility was $424.1 million and $608.0 million, respectively.

$65.0 million Letter of Credit Facility

On August 4, 2020, we entered into a $65.0 million letter of credit facility agreement pursuant to which we issued a letter of credit to collateralize a portion of our reinsurance obligations relating to our novation transaction

with Hannover Re, which we completed on August 6, 2020, as discussed in Note 4 - "Significant New Business". As of December 31, 2020, the aggregate amount of letters of credit issued under the facility was $61.0 million.

Subsidiary Capital Letters of Credit

We also utilize unsecured and secured letters of credit to support the regulatory capital requirements of certain of our subsidiaries.

$100.0 million Bermuda Letter of Credit Facility

On December 22, 2017, we entered into a $100.0 million subsidiary capital letter of credit facility agreement. The letter of credit issued under the agreement qualifies as eligible capital for one of our Bermuda regulated subsidiaries. As of December 31, 2020, the aggregate face amount of letters of credit under the facility was $100.0 million.

GBP £32.0 million United Kingdom Letter of Credit Facility

On December 8, 2020, we entered into a £32.0 million ($43.7 million) subsidiary capital letter of credit facility agreement. The letter of credit issued under the agreement qualifies as Ancillary Own Funds capital for one of our U.K. regulated subsidiaries. As of December 31, 2020, the aggregate face amount of letters of credit under the facility was $43.7 million.

Noncontrolling Interest

12 Months Ended

Dec. 31, 2020

Noncontrolling Interest [Abstract]

Noncontrolling Interest

16. NONCONTROLLING INTEREST We have both redeemable noncontrolling interest ("RNCI") and noncontrolling interest ("NCI") on our consolidated balance sheets. RNCI with redemption features that are not solely within our control are classified within temporary equity in the consolidated balance sheets and carried at redemption value, which is fair value. The change in fair value is recognized through retained earnings as if the balance sheet date were also the redemption date. In addition, we also have NCI, which does not have redemption features and is classified within equity in the consolidated balance sheets.

Redeemable Noncontrolling Interest

RNCI as of December 31, 2020 and 2019 comprised the ownership interests held by the Trident V Funds (39.3%) and the Dowling Funds (1.7%) in our subsidiary North Bay. As discussed in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations," North Bay owned our investments in Northshore, the holding company that owns Atrium and Arden, and SSHL, the holding company for the StarStone group.

The following is a reconciliation of the beginning and ending carrying amount of the equity attributable to the RNCI for the years ended December 31, 2020 and 2019:


	2020		2019
Balance at beginning of year	$	438,791	$	458,543
Capital contributions	—		13,127
Dividends paid	—		(11,556)
Net losses attributable to RNCI	(27,512)		(12,029)
Change in unrealized gains (losses) on AFS investments attributable to RNCI	1,517		(126)
Change in currency translation adjustments attributable to RNCI	(1,397)		10

Change in redemption value of RNCI	(46,224)		(9,178)
Cumulative effect of change in accounting principle attributable to RNCI (1)	261		—
Balance at end of year	$	365,436	$	438,791

(1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details.

We carried the RNCI at its estimated redemption value, which is fair value, as of December 31, 2020 and 2019. The decrease in the year ended December 31, 2020 included $27.5 million of net losses attributable to RNCI primarily arising on StarStone and which result from COVID-19 related net underwriting losses and exit costs associated with the decision to place StarStone International into run-off, partially offset by the gain on sale of StarStone U.S.; and $46.2 million due to change in redemption value. The redemption value decreased as a result of the StarStone International Run-Off decision and the agreement to sell both StarStone U.S and Northshore.

Following the completion of the Atrium Exchange Transaction on January 1, 2021, as described in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations," we will deconsolidate the RNCI relating to Northshore in the first quarter of 2021, and thereafter the remaining RNCI will be for StarStone International.Refer to Note 23 - "Commitments and Contingencies" for additional information regarding RNCI.Noncontrolling InterestAs of December 31, 2020 and 2019, we had $13.6 million and $14.2 million, respectively, of NCI primarily related to external interests in three of our subsidiaries. A reconciliation of the beginning and ending carrying amount of the equity attributable to NCI is included in the consolidated statement of changes in shareholders equity.

Shareholders' Equity

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Shareholders' Equity

17. SHAREHOLDERS' EQUITY

As of December 31, 2020 and 2019, the authorized share capital was 111,000,000 ordinary shares ("Voting Ordinary Shares") and non-voting convertible ordinary shares ("Non-Voting Ordinary Shares"), each of par value $1.00 per share, and 45,000,000 preferred shares of par value $1.00 per share.

Voting Ordinary Shares

Our Voting Ordinary Shares are listed and trade under the "ESGR" ticker symbol on the NASDAQ Global Select Market. Each Voting Ordinary Share entitles the holder thereof to one vote.

Share Repurchases

On March 9, 2020, our Board of Directors adopted a stock trading plan for the purpose of repurchasing a limited number of our Company’s ordinary shares, not to exceed $150.0 million in aggregate (the "Repurchase Program"). On March 23, 2020, we suspended our Repurchase Program due to uncertainty from the COVID-19 pandemic. The Repurchase Program resumed on September 21, 2020 and expires on March 1, 2021.

From inception to December 31, 2020, we repurchased 178,280 ordinary shares at an average price of 145.87, for an aggregate price of $26.0 million under the Repurchase Program. As of December 31, 2020, the remaining capacity under the Repurchase Program was $124.0 million. We did not repurchase any shares subsequent to December 31, 2020.

Joint Share Ownership Plan

On January 21, 2020, 565,630 Voting Ordinary Shares were issued to the trustee of the Enstar Group Limited Employee Benefit Trust (the "EB Trust"). Voting rights in respect of shares held in the EB Trust have been contractually waived. We have consolidated the EB Trust, and shares held in the EB Trust are classified like treasury shares as contra-equity in our consolidated balance sheet. The EB Trust supports awards made under our Joint Share Ownership Plan, as described in Note 19 - "Share-Based Compensation and Pensions."

Shares issued in acquisition of KaylaRe

On May 14, 2018, 1,501,778 Voting Ordinary Shares were issued as consideration for the acquisition of KaylaRe Holdings Ltd, as described in Note 3 - "Business Acquisitions".

Non-Voting Ordinary SharesThe Non-Voting Ordinary Shares are comprised of several different series as of December 31, 2020:the Series C shares were originally issued in connection with investment transactions in April and December of 2011 and on exercise of warrants in March 2017. The Series C shares: (i) have all of the economic rights (including dividend rights) attaching to Voting Ordinary Shares but are non-voting except in certain limited circumstances; (ii) will automatically convert at a one-for-one exchange ratio (subject to adjustment for share splits, dividends, recapitalizations, consolidations or similar transactions) into Voting Ordinary Shares if the registered holder transfers them in a widely dispersed offering; (iii) may only vote on certain limited matters that would constitute a variation of class rights and as required under Bermuda law, provided that the aggregate voting power of the Series C shares with respect to any merger, consolidation or amalgamation will not exceed 0.01% of the aggregate voting power of our issued share capital; and (iv) require the registered holders’ written consent in order to vary the rights of the shares in a significant and adverse manner. the Series B and Series D shares were created in connection with the 2011 investment transactions, but no shares in these series are issued and outstanding. Holders of the Series C shares have the right to convert such shares, on a share-for-share basis, subject to certain adjustments, into Series D shares at their option. There is no economic difference in Series B, C or D shares, but there are slight differences in the conversion rights and the limited voting rights of each series.there were 910,010 Series E shares issued and outstanding as of December 31, 2020. On May 14, 2018, 505,239 Series E non-voting shares were issued as consideration for the acquisition of KaylaRe Holdings Ltd, as described in Note 3 - "Business Acquisitions". The Series E shares have substantially the same rights as the Series C shares, except that (i) they are convertible only into Voting Ordinary Shares and (ii) they may only vote as required under Bermuda law. The Series E shares include all other Non-Voting Ordinary Shares authorized under our bye-laws but not classified as Series A, B, C or D Non-Voting Ordinary Shares.

Warrants

As of December 31, 2020, there were warrants outstanding to acquire 175,901 Series C Non-Voting Ordinary Shares for an exercise price of $115.00 per share, subject to certain adjustments (the "Warrants"). The Warrants were issued in April 2011 and expire in April 2021.

Series C Preferred Shares

As of December 31, 2020, there were 388,571 Series C Participating Non-Voting Perpetual Preferred Shares ("Series C Preferred Shares") issued and held by one of our wholly-owned subsidiaries. The Series C Preferred Shares (i) upon liquidation, dissolution or winding up of the Company, entitle their holders to a preference over holders of our ordinary voting and non-voting shares of an amount equal to $0.001 per share with respect to surplus assets and (ii) are non-voting except in certain limited circumstances. The Series C Preferred shares have dividend rights equal to those of the ordinary voting shares, subject to certain limitations and in an amount determined by a "participation rate" that is generally reflective of the reduction in the number of Series C Preferred Shares issued in exchange for the previously outstanding Series A Shares. The Series C Preferred Shares otherwise rank on parity with the ordinary voting and non-voting shares, and they rank senior to each other class or series of share capital, unless the terms of any such class or series shall expressly provide otherwise.

Series D Preferred SharesOn June 28, 2018, the Company raised $400.0 million of gross proceeds through the public offering of 16,000 shares of its 7.00% non-cumulative fixed-to-floating rate Series D perpetual preferred shares ("Series D Preferred Shares") (equivalent to 16,000,000 depositary shares, each of which represents a 1/1,000th interest in a Series D Preferred Share), $1.00 par value and $25,000 liquidation preference (the "Liquidation Preference") per share (equivalent to $25.00 per depositary share). The depositary shares are listed and trade under the "ESGRP" ticker symbol on the NASDAQ Global Select Market. The Series D Preferred Shares are not redeemable prior to September 1, 2028, except in specified circumstances as described in the prospectus supplement relating to the offering. On and after September 1, 2028, the Series D Preferred Shares, represented by the depositary shares, will be redeemable at the Company’s option, in whole or from time to time in part, at a redemption price equal to $25,000 per Series D Preferred Share (equivalent to $25.00 per depositary share), plus any declared and unpaid dividends.Series E Preferred SharesOn November 21, 2018, the Company raised $110.0 million of gross proceeds through the public offering of 4,400 shares of its 7.00% fixed rate non-cumulative Series E perpetual preferred shares ("Series E Preferred Shares") (equivalent to 4,400,000 depositary shares, each of which represents a 1/1,000th interest in a Series E Preferred Share), $1.00 par value and $25,000 liquidation preference (the "Series E Liquidation Preference") per share (equivalent to $25.00 per depositary share). The depositary shares are listed and trade under the "ESGRO" ticker symbol on the NASDAQ Global Select Market. The Series E Preferred Shares are not redeemable prior to March 1, 2024, except in specified circumstances as described in the prospectus supplement relating to the offering. On and after March 1, 2024, the Series E Preferred Shares, represented by the depositary shares, will be redeemable at the Company’s option, in whole or from time to time in part, at a redemption price equal to $25,000 per Series E Preferred Share (equivalent to $25.00 per depositary share), plus any declared and unpaid dividends.

Dividends on Preferred Shares

Holders of Series D and Series E Preferred Shares are entitled to receive, only when, as and if declared, non-cumulative cash dividends, paid quarterly in arrears on the 1st day of March, June, September and December of each year, commencing on September 1, 2018 for the Series D Preferred Shares and March 1, 2019 for the Series

E Preferred Shares, of 7.00% per annum. Commencing on September 1, 2028, the Series D Preferred Shares will convert to a floating rate basis and dividends will be payable on a non-cumulative basis, when, as and if declared, at three-month LIBOR plus 4.015% per annum. Dividends that are not declared will not accumulate and will not be payable. During the years ended December 31, 2020, 2019 and 2018, we declared and paid dividends on Series D Preferred Shares of $28.0 million, $28.0 million and $12.1 million, respectively. During the years ended December 31, 2020 and 2019, we declared and paid dividends on Series E Preferred Shares of $7.7 million and $7.9 million, respectively. On February 5, 2021, we declared $7.0 million and $1.9 million of dividends on the Series D and E Preferred Shares, respectively, to be paid on March 1, 2021 to shareholders of record as of February 15, 2021.

Any payment of dividends must be approved by our Board of Directors. Our ability to pay dividends is subject to certain restrictions, as described in Note 22 - "Dividend Restrictions and Statutory Financial Information".

The following table presents a roll forward of accumulated other comprehensive income (loss):


	Unrealized gains (losses) arising during the year		Cumulative Currency Translation Adjustment		Defined Benefit Pension Liability		Total
Balance, December 31, 2017, net of tax	$	2,440	$	11,171	$	(3,143)	$	10,468
Unrealized gains (losses) on fixed income available-for-sale investments arising during the year	(2,284)		—		—		(2,284)
Reclassification adjustment for net realized (gains) losses included in net earnings	63		—		—		63
Change in currency translation adjustment	—		(202)		—		(202)
Decrease in defined benefit pension liability	—		—		2,156		2,156
Total other comprehensive income (loss)	(2,221)		(202)		2,156		(267)
Other comprehensive (income) loss attributable to RNCI	222		17		—		239
Balance, December 31, 2018, net of tax	441		10,986		(987)		10,440
Unrealized gains (losses) on fixed income available-for-sale investments arising during the year	2,896		—		—		2,896
Reclassification adjustment for net realized (gains) losses included in net earnings	(3,894)		—		—		(3,894)
Change in currency translation adjustment	—		(2,428)		—		(2,428)
Decrease in defined benefit pension liability	—		—		42		42
Total other comprehensive income (loss)	(998)		(2,428)		42		(3,384)
Other comprehensive (income) loss attributable to RNCI	125		(10)		—		115
Balance, December 31, 2019, net of tax	(432)		8,548		(945)		7,171
Unrealized gains (losses) on fixed income available-for-sale investments arising during the year	104,924		—		—		104,924
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(509)		—		—		(509)
Reclassification adjustment for net realized (gains) losses included in net earnings	(18,033)		—		—		(18,033)
Reclassification to earnings on disposal of subsidiary	(11,856)		34		—		(11,822)
Change in currency translation adjustment	—		(2,103)		—		(2,103)
Decrease in defined benefit pension liability	—		—		1,152		1,152
Total other comprehensive income (loss)	74,526		(2,069)		1,152		73,609
Other comprehensive (income) loss attributable to RNCI	(1,518)		1,397		—		(121)
Balance, December 31, 2020, net of tax	$	72,576	$	7,876	$	207	$	80,659

The following table presents details about the tax effects allocated to each component of other comprehensive income (loss):


	Before Tax Amount		Tax (Expense) Benefit		Net of Tax Amount
Twelve months ended December 31, 2020
Unrealized gains (losses) on fixed income available-for-sale investments arising during the year	$	115,610	$	(10,686)	$	104,924
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(499)		(10)		(509)
Reclassification adjustment for net realized (gains) losses included in net earnings	(19,766)		1,733		(18,033)
Reclassification to earnings on disposal of subsidiary	(15,008)		3,152		(11,856)
Change in currency translation adjustment	(2,294)		191		(2,103)
Reclassification to earnings on disposal of subsidiary	34		—		34
Decrease in defined benefit pension liability	1,097		55		1,152
Other comprehensive income (loss)	$	79,174	$	(5,565)	$	73,609

In the year ended December 31, 2019 and 2018, the deferred tax (expense) benefit associated with items reported in other comprehensive income (loss) was subject to a full valuation allowance. For information on valuation allowances on deferred tax assets, refer to “Assessment of Valuation Allowance on Deferred Tax Assets” within Note 20 - "Income Taxation."

The following table presents details amounts reclassified from accumulated other comprehensive income:


Details about AOCI components	2020	2019	2018	Affected Line Item in Statement where Net Earnings are presented
Unrealized gains (losses) on fixed income available-for-sale investments	18,682	3,894	(63)	Net realized and unrealized gains (losses)
	16,591	—	—	Net earnings from discontinued operations
	35,273	3,894	(63)	Total before tax
	(4,875)	—	—	Income tax (expense)
	30,398	3,894	(63)	Net of tax
Currency translation adjustment on disposal of subsidiary	(34)	—	—	Net earnings from discontinued operations
Total reclassifications for the period, net of tax	30,364	3,894	(63)

Earnings Per Share

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Earnings Per Share

18. EARNINGS PER SHARE

The following table sets forth the computation of basic and diluted net earnings per ordinary share for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Numerator:
Earnings (loss) per share attributable to Enstar ordinary shareholders:
Net earnings (loss) from continuing operations(1)	$	1,711,810	$	897,825	$	(163,232)
Net earnings from discontinued operations(2)	7,534		4,350		878
Net earnings (loss) attributable to Enstar ordinary shareholders	$	1,719,344	$	902,175	$	(162,354)
Denominator:
Weighted-average ordinary shares outstanding — basic(3)	21,551,408		21,482,617		20,698,310
Effect of dilutive securities:
Share-based compensation plans(4)	208,293		227,878		129,746
Warrants	58,593		64,571		76,120

Weighted-average ordinary shares outstanding — diluted	21,818,294		21,775,066		20,904,176
Earnings (loss) per share attributable to Enstar ordinary shareholders:
Basic:
Net earnings (loss) from continuing operations	$	79.43	$	41.80	$	(7.89)
Net earnings from discontinued operations	0.35		0.20		0.05
Net earnings (loss) per ordinary share	$	79.78	$	42.00	$	(7.84)
Diluted (5):
Net earnings (loss) from continuing operations	$	78.45	$	41.23	$	(7.89)
Net earnings from discontinued operations	0.35		0.20		0.05
Net earnings (loss) per ordinary share	$	78.80	$	41.43	$	(7.84)

(1) Net earnings (loss) from continuing operations attributable to Enstar ordinary shareholders equals net earnings (loss) from continuing operations, plus net loss (earnings) from continuing operations attributable to noncontrolling interest, less dividends on preferred shares.

(2) Net earnings (loss) from discontinued operations attributable to Enstar ordinary shareholders equals net earnings (loss) from discontinued operations, net of income taxes, plus net loss (earnings) from discontinued operations attributable to noncontrolling interest; refer to Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations" for a breakdown by period.

(3) Weighted-average ordinary shares for basic earnings per share includes ordinary shares (voting and non-voting) but excludes ordinary shares held in the EB Trust in respect of JSOP awards.

(4) Share-based dilutive securities include restricted shares, restricted share units, and performance share units. Certain share-based compensation awards, including the ordinary shares held in the EB Trust in respect of JSOP awards, were excluded from the calculation for the year ended December 31, 2020 because they were anti-dilutive.

(5) During a period of loss, the basic weighted average ordinary shares outstanding is used in the denominator of the diluted loss per ordinary share computation as the effect of including potentially dilutive securities would be anti-dilutive.

Share-Based Compensation and Pensions

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Share-Based Compensation and Pensions

19. SHARE-BASED COMPENSATION AND PENSIONS

Share-based compensation

The 2016 and 2006 Equity Incentive Plans are our primary share-based compensation plans. We also maintain other share-based compensation plans as discussed below. The table below provides a summary of the compensation costs for all of our share-based compensation plans for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Share-based compensation plans:
Restricted shares and restricted share units	$	8,286	$	6,564	$	7,641
Performance share units	12,678		23,582		1,968
Cash-settled stock appreciation rights	215		2,575		(3,316)
Joint share ownership plan expense	4,296		—		—
Other share-based compensation plans:
Northshore/Atrium incentive plan	971		3,652		2,792
StarStone incentive plan	(223)		223		—
Deferred compensation and ordinary share plan for non-employee directors	1,183		992		1,155
Employee share purchase plan	339		411		430
Total share-based compensation	$	27,745	$	37,999	$	10,670

The associated tax benefit recorded to income tax expense in the Consolidated statement of operations was $2.7 million, $2.9 million and $1.9 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Restricted Shares and Restricted Share Units

Restricted shares and restricted share units are service awards that typically vest over three years. These awards are share-settled and are recorded in additional paid-in capital on the consolidated balance sheets. The fair value of these awards is measured at the grant date and expensed over the service period. The following table summarizes the activity related to restricted shares and restricted share awards during 2020:


	Number of Shares	Weighted-Average Share Price
Nonvested — January 1	64,572	$180.49
Granted	70,012	152.28
Vested	(38,961)	174.93
Forfeited	(373)	177.73
Nonvested — December 31	95,250	161.60

The unrecognized compensation cost related to our unvested restricted share and restricted share unit awards as of December 31, 2020 was $7.9 million. This cost is recognizable over the next 2.07 years, which is the weighted average contractual life.

Performance Share Units ("PSUs")

PSUs are share-settled and vest following the end of the three-year performance period. The number of shares to vest will be determined by a performance adjustment based on either (i) the change in fully diluted book value per share ("FDBVPS") over three years, or (ii) average annual non-GAAP operating income return on equity, excluding StarStone.

Performance Share Units based on FDBVPS

The following table summarizes the awards granted, the vested and unvested PSU awards at December 31, 2020, and the performance criteria and associated performance multipliers at various levels of achievement.


Grant Year	Inception-to-date Activity Roll-forward					Performance Criteria: Change in FDBVPS (3 year)								Performance Multiplier Levels Per Award Agreements
	PSUs Granted at Target	Forfeited	Estimated Change in Multiplier	Vested	Unvested at December 31, 2020	Threshold		Target		Target +		Maximum		Threshold		Target		Target +		Maximum
2017	36,321	(12,267)	9,527	(33,581)	—	20.00	%	30.00	%	N/A		40.00	%	50.00	%	100.00	%	N/A		150.00	%
2017	91,875	—	18,100	(109,975)	—	30.30	%	35.65	%	N/A		41.00	%	50.00	%	100.00	%	N/A		150.00	%
2018	39,682	(12,545)	10,218	(6,700)	30,655	25.00	%	32.50	%	N/A		40.00	%	50.00	%	100.00	%	N/A		150.00	%
2019	18,308	(1,758)	7,835	(881)	23,504	20.00	%	30.00	%	N/A		40.00	%	60.00	%	100.00	%	N/A		150.00	%
2020	22,591	(2,151)	—	(701)	19,739	25.00	%	32.50	%	N/A		40.00	%	60.00	%	100.00	%	N/A		150.00	%
2020	52,948	—	—	—	52,948	33.10	%	36.80	%	44.30	%	52.10	%	50.00	%	100.00	%	150.00	%	200.00	%
	261,725	(28,721)	45,680	(151,838)	126,846

For each type of PSU based on FDBVPS, a change in the FDBVPS Performance Criteria at each of Threshold, Target and Maximum will result in the application of the respective Threshold, Target and Maximum Performance Multiplier and a settlement of awards at that level. In addition, for the 2020 FDBVPS Type II award, a change in the FDBVPS Performance Criteria at "Target +" will result in the application of the "Target +" Performance Multiplier. Straight-line interpolation applies within these ranges, and no settlement occurs if the increase in FDBVPS is less than the Threshold.

Performance Share Units based on Average Annual Non-GAAP Operating Income Return on Equity ("Operating ROE")

The following table summarizes the awards granted, the vested and unvested units at December 31, 2020, and the performance criteria and associated performance multipliers at various levels of achievement.


Grant Year	Inception-to-date Activity Roll-forward					Performance Criteria: Average Annual Operating ROE						Performance Multiplier Levels Per Award Agreements
	PSUs Granted at Target	Forfeited	Estimated Change in Multiplier	Vested	Unvested at December 31, 2020	Threshold		Target		Maximum		Threshold		Target		Maximum
2019	18,308	(1,756)	7,811	(930)	23,433	9.60	%	12.00	%	14.40	%	60.00	%	100.00	%	150.00	%
2020	22,560	(2,151)	—	(701)	19,708	9.60	%	12.00	%	14.40	%	60.00	%	100.00	%	150.00	%
	40,868	(3,907)	7,811	(1,631)	43,141

Annual Operating ROE is calculated based upon the non-GAAP operating income return on opening shareholder's equity, excluding StarStone. Average Annual Operating ROE is the sum of the three individual year annual operating ROE %'s divided by three. An Average Annual Operating ROE of Target to Maximum or more results in a settlement of 100% to a maximum of 150% of the units granted, respectively. An Average Annual Operating ROE of Threshold to Target results in a settlement of 60% to 100%. Straight-line interpolation applies within these ranges and no settlement occurs if the Average Annual Operating ROE is less than the Threshold.

Performance Multipliers

For expense purposes we assume a Target vesting at the initial time of award. At the end of each reporting period, we estimate the expected performance multiplier, as shown in the table below:


Award Description	2020		2019	2018
2017 FDBVPS Type I (30.00% Target Change)	139%	(1)	139%	50%
2017 FDBVPS Type II (35.65% Target Change)	120%	(1)	120%	50%
2018 FDBVPS	150%	(1)	100%	50%
2019 FDBVPS	150%		100%	N/A
2019 Average Operating ROE	150%		100%	N/A
2020 FDBVPS Type I (32.50% Target Change)	100%		N/A	N/A
2020 Average Operating ROE	100%		N/A	N/A
2020 FDBVPS Type II (36.80% Target Change)	100%		N/A	N/A

(1) Multipliers for the 2017 and 2018 awards are the final achieved terms.

The unrecognized compensation cost related to our unvested PSU share awards as of December 31, 2020 was $14.4 million. This cost is recognizable over the next 1.9 years, which is the weighted average contractual life.

Roll-forward of Performance Share Units

The following table summarizes the activity related to PSUs during 2020:


	Number of Shares	Weighted-Average Share Price
Nonvested — January 1	206,949	$185.61
Granted	98,099	167.94
Change in performance multiplier	25,850	179.71
Vested	(153,469)	187.24
Forfeited	(7,442)	146.76
Nonvested — December 31	169,987	174.10

Cash-Settled Stock Appreciation Rights

Cash-settled stock appreciation right awards ("SARs") give the holder the right, upon exercise, to receive in cash the difference between the market price per share of our ordinary shares at the time of exercise and the exercise price of the SARs. The exercise price of each SAR is equal to the market price of our ordinary shares on the date of the grant. Vested SARs are exercisable for periods not to exceed either 4 years or 10 years from the date of grant. We have not granted any new SARs since 2015.

The following table summarizes the activity related to SARs during 2020:


	Number of SARs	Weighted-Average Exercise Price of SARs		Weighted-Average Expected Term (in years)	Aggregate Intrinsic Value(1)
Balance, beginning of year	89,227	$	143.33
Exercised	(12,793)	136.94

Balance, end of year	76,434	144.40		1.90	$	4,623

(1) The aggregate intrinsic value is calculated as the pre-tax difference between the exercise price of the underlying share awards and the closing price per share of our ordinary shares of $204.89 on December 31, 2020.

Compensation expense for SARs is based on the estimated fair value on the date of grant using the Black-Scholes valuation model, which requires the use of subjective assumptions related to the expected stock price volatility, expected term, expected dividend yield and risk-free interest rate. SARs are liability-classified awards for which compensation expense and the liability are re-measured using the then-current Black Scholes assumptions at each interim reporting date based upon the portion of the requisite service period rendered. There was no unrecognized compensation cost related to our SARs as of December 31, 2020.

The following table sets forth the assumptions used to estimate the fair value of the SARs using the Black-Scholes option valuation model as of December 31, 2020, 2019 and 2018:


	2020			2019			2018
Weighted-average fair value per SAR	$	78.47		$	76.03		$	45.85
Weighted-average volatility	49.43		%	19.75		%	18.94		%
Weighted-average risk-free interest rate	0.15		%	1.64		%	2.72		%
Dividend yield	0.00		%	0.00		%	0.00		%

Joint Share Ownership Plan

Under the JSOP, we have the ability to make equity awards to our U.K.-based staff through which a recipient acquires jointly held interests in a set number of our Voting Ordinary Shares together with the independent trustee of the EB Trust at fair market value, pursuant to the terms of a joint ownership agreement. Voting rights in respect of shares held in the EB Trust are contractually waived. Shares held in the EB Trust are classified as treasury shares.

On January 21, 2020, a JSOP award comprising 565,630 underlying Voting Ordinary Shares was made to our Chief Executive Officer which cliff-vests after 3 years. The value of the award at vesting, if any, is determined based on the price of our Voting Ordinary Shares appreciating above a certain threshold between the date of grant and the vesting date. If the higher of the closing price per Share on January 20, 2023 and the 10-day volume weighted average price per Share for the ten consecutive trading days ending on January 20, 2023 (each, the "Market Price") is $266.00 or greater (the "Hurdle"), the award will have a value equal to the Market Price, less $205.89, multiplied

by 565,630. If the Market Price is less than $266.00 on such date, the award will have no value. In addition, 20% of the award is subject to a performance condition based on growth in fully diluted book value per share between January 1, 2020 and December 31, 2022.

The accounting for stock-settled JSOP awards is similar to options, whereby the grant date fair value of $13.6 million is expensed over the life of the award. To determine the grant date fair value of $24.13 per share, we utilized a Monte-Carlo valuation model with the following assumptions:


	2020

Weighted-average volatility	18.66	%
Weighted-average risk-free interest rate	1.55	%
Dividend yield	0.00	%

The unrecognized compensation cost related to our unvested JSOP share awards as of December 31, 2020 was $9.4 million. This cost is recognizable over the next 2.1 years, which is the weighted average contractual life.

Other share-based compensation plans

Northshore and Atrium Incentive Plans

Our subsidiary, Northshore, had long-term incentive plans that award time-based restricted shares of Northshore to certain Atrium employees. Shares generally vested over two to three years. These share awards have been classified as liability awards. There is no unrecognized compensation as we de-consolidated Northshore on January 1, 2021 as discussed in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations."

StarStone Incentive Plan

Our subsidiary, StarStone, had long-term incentive plans that were cash-settled plans for StarStone employees. The awards were based on StarStone's performance over two to three years. These share awards were classified as liability awards. The plan was terminated and awards settled during 2020. There is no unrecognized compensation cost.

Deferred Compensation and Ordinary Share Plan for Non-Employee Directors

The number of units credited to the accounts of non-employee directors for the years ended December 31, 2020, 2019 and 2018 under the Enstar Group Limited Deferred Compensation and Ordinary Share Plan for Non-Employee Directors (the "Deferred Compensation Plan") were 7,204, 5,976 and 5,691, respectively.

Employee Share Purchase Plan

We provide an Employee Share Purchase Plan whereby eligible employees may purchase Enstar shares at a 15% discount to market price, in an amount of share value limited to the lower of $21,250 or 15% of the employee's base salary. The 15% discount is expensed as compensation cost. The number of shares issued to employees under the Employee Share Purchase Plan for the years ended December 31, 2020, 2019 and 2018 were 16,914, 15,269 and 14,183, respectively.

Pension Plans

We provide retirement benefits to eligible employees through various plans that we sponsor. Pension expense can be affected by changes in our employee headcount. The table below summarizes the expense related to our Defined Contribution Plans and our Defined Benefit Plan for the years ended December 31, 2020, 2019 and 2018.


	2020		2019		2018
Defined contribution plans	$	11,791	$	11,798	$	11,434
Defined benefit plan	2,975		684		2,243
Total pension expense	$	14,766	$	12,482	$	13,677

The increase in the 2020 defined benefit plan pension expense was driven by annuity purchases for partial risk transfer of certain plan liabilities. During 2020, an actuarial review was performed on the defined benefit plan, which determined that the plan’s unfunded liability, as of December 31, 2020 and 2019 was $6.9 million and $8.9 million, respectively. As of December 31, 2020 and 2019, we had an accrued liability of $6.9 million and $8.9 million, respectively, for this plan.

Income Taxation

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxation

20. INCOME TAXATION

Enstar Group Limited is incorporated under the laws of Bermuda and under Bermuda law is not required to pay taxes in Bermuda based upon income or capital gains. The Company, under the Exempted Undertakings Tax Protection Act of 1966, is protected against any legislation that may be enacted in Bermuda which would impose any tax on profits, income, or gain until March 31, 2035.

We have foreign operating subsidiaries and branch operations principally located in the United States, United Kingdom, Continental Europe and Australia that are subject to federal, foreign, state and local taxes in those jurisdictions. The undistributed earnings from our foreign subsidiaries will be indefinitely reinvested in those jurisdictions where the undistributed earnings were earned.

Deferred tax liabilities have not been accrued with respect to the undistributed earnings of our foreign subsidiaries. Generally, when earnings are distributed as dividends, withholding taxes may be imposed by the jurisdiction of the paying subsidiary. For our U.S. subsidiaries, we have not currently accrued any withholding taxes with respect to unremitted earnings because, solely for U.S. Federal income tax purposes, there are no accumulated positive earnings and profits that could be subject to U.S. dividend withholding tax. For our United Kingdom subsidiaries, there are no withholding taxes imposed as a matter of UK domestic tax law. For our other foreign subsidiaries, an insignificant amount of earnings is indefinitely reinvested; however, it would not be practicable to compute the related amounts of withholding taxes due to a variety of factors, including the amount, timing and manner of any repatriation. Because we operate in many jurisdictions, our net earnings are subject to risk due to changing tax laws and tax rates around the world. The current, rapidly changing economic environment may increase the likelihood of substantial changes to tax laws in the jurisdictions in which we operate.

Income Tax Expense

The following table presents earnings (loss) before income taxes by jurisdiction attributable to continuing operations, including earnings from equity method investments, for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Domestic (Bermuda)	$	1,503,505	$	576,338	$	(232,743)
Foreign	231,444		356,878		15,293
Total earnings (loss) before income taxes attributable to continuing operations	$	1,734,949	$	933,216	$	(217,450)

The following table presents our current and deferred income tax expense (benefit) attributable to continuing operations by jurisdiction for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Current:
Domestic (Bermuda)	$	—	$	—	$	—
Foreign	15,232		16,330		(917)
	15,232		16,330		(917)
Deferred:
Domestic (Bermuda)	—		—		—
Foreign	8,595		(3,958)		(2,772)
	8,595		(3,958)		(2,772)
Total income tax expense (benefit) attributable to continuing operations	$	23,827	$	12,372	$	(3,689)

The actual effective income tax rate differs from the statutory rate of 0 percent under Bermuda law to earnings (loss) attributable to continuing operations before income taxes, including earnings (loss) from equity method investments for the years ended December 31, 2020, 2019 and 2018 as shown in the following reconciliation:


	2020			2019			2018
Earnings (loss) before income taxes	$	1,734,949		$	933,216		$	(217,450)
Bermuda income taxes at statutory rate	0.0		%	0.0		%	0.0		%
Foreign income tax rate differential	1.2		%	8.6		%	0.6		%



Change in valuation allowance	0.1		%	(7.2)		%	(1.8)		%


U.S. base erosion and anti-abuse tax	—		%	0.3		%	(0.3)		%


Other	0.1		%	(0.4)		%	3.2		%
Effective tax rate	1.4		%	1.3		%	1.7		%

Our effective tax rate is generally driven by the geographical distribution of our pre-tax earnings between our taxable and non-taxable jurisdictions.

Deferred Tax Assets and Liabilities

Deferred tax assets and liabilities (included in other assets and other liabilities, respectively, on the consolidated balance sheet) reflect the tax effect of the differences between the financial statement carrying amount and the income tax bases of assets and liabilities. Significant components of the deferred tax assets and deferred tax liabilities as of December 31, 2020 and 2019 were as follows:


	2020		2019
Deferred tax assets:
Net operating loss carryforwards	$	141,459	$	144,609

Insurance reserves	22,238		7,535
Unearned premiums	68		151

Provisions for bad debt	407		6,172

Defendant asbestos and environmental liabilities	121,006		140,000
Other deferred tax assets	16,696		3,230
Deferred tax assets	301,874		301,697
Valuation allowance	(118,229)		(117,390)
Deferred tax assets, net of valuation allowance	183,645		184,307

Deferred tax liabilities:
Unrealized gains on investments	(20,185)		(14,079)
Lloyd's underwriting profit taxable in future periods	(15,555)		(8,852)
Deferred policy acquisition cost	—		(8,267)
Other deferred tax liabilities	(9,242)		(13,390)
Deferred tax liabilities	(44,982)		(44,588)

Net deferred tax asset	$	138,663	$	139,719

Net Deferred Tax Asset (Liability) Balance by Major Jurisdiction:


	December 31,
	2020		2019
	Net Deferred Tax Asset		Net Deferred Tax Asset

United States	$	156,730	$	154,700
United Kingdom	(18,095)		(16,074)
Other	28		1,093
Total	$	138,663	$	139,719

Net Operating Loss Carryforwards:

As of December 31, 2020, we had net operating loss carryforwards that could be available to offset future taxable income, as follows:


Tax Jurisdiction	Loss Carryforwards		Tax effect		Expiration
Operating and Capital Loss Carryforwards:
United States - Net operating loss	$	428,732	$	90,034	2024-2038

United Kingdom	185,230		35,194		Indefinitely
Luxembourg	17,200		4,300		2035-2036
Other	48,683		11,931		Indefinitely

The U.S. and UK net operating loss carryforwards are also subject to certain utilization limitations and have been considered in management's assessment of Valuation Allowance.

Assessment of Valuation Allowance on Deferred Tax Assets

As of December 31, 2020 and 2019, we had deferred tax asset valuation allowances of $118.2 million and $117.4 million, respectively, related to foreign subsidiaries. We recorded a net increase of $0.8 million in our deferred tax valuation allowance primarily due to a change in deferred tax assets which management does not believe meet the "more likely than not" realization standard.

The realization of deferred tax assets is dependent on generating sufficient taxable income in future periods in which the tax benefits are deductible or creditable. The amount of the deferred tax asset considered realizable, however, could be revised in the future if estimates of future taxable income change. Income taxes are determined and assessed jurisdictionally by legal entity or by filing group. Certain jurisdictions require or allow combined or consolidated tax filings. We have estimated future taxable income of our foreign subsidiaries and provided a valuation allowance in respect of those assets where we do not expect to realize a benefit. We have considered all available evidence using a “more likely than not” standard in determining the amount of the valuation allowance. We considered the following evidence: (i) net earnings or losses in recent years; (ii) the future sustainability and likelihood of positive net earnings of our subsidiaries; (iii) the carryforward periods of tax losses including the effect of reversing temporary differences; and (iv) tax planning strategies, in making our determination. The assumptions used in determining future taxable income require significant judgment and any changes in these assumptions could have an impact on earnings.

Unrecognized Tax Benefits

During the years ended December 31, 2020, 2019 and 2018, there were no unrecognized tax benefits. There were no accruals for the payment of interest and penalties related to unrecognized tax benefits as of each of December 31, 2020, 2019 and 2018.

Open Tax Years

Our operating subsidiaries may be subject to audit by various tax authorities and may have different statutes of limitations expiration dates. Tax authorities may propose adjustments to our income taxes. Listed below are the tax years that remain subject to examination by a major tax jurisdiction as of December 31, 2020:

Major Tax Jurisdiction

Open Tax Years

United States

2017-2020

United Kingdom

2019-2020

Australia

2015-2020

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

Related Party Transactions

Related Party Transactions

12 Months Ended

Dec. 31, 2020

21. RELATED PARTY TRANSACTIONSStone Point Capital LLCThrough several private transactions occurring from May 2012 to July 2012 and an additional private transaction that closed in May 2018, investment funds managed by Stone Point Capital LLC ("Stone Point") have acquired an aggregate of 1,635,986 of our Voting Ordinary Shares (which constitutes 8.8% of our outstanding Voting Ordinary Shares). On November 6, 2013, we appointed James D. Carey to our Board of Directors. Mr. Carey is the sole member of an entity that is one of four general partners of the entities serving as general partners for Trident, is a member of the investment committees of such general partners, and is a member and senior principal

of Stone Point, the manager of the Trident funds.

On November 30, 2020, we completed the sale and recapitalization of StarStone U.S. to Core Specialty in a transaction described in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations".

Pursuant to the terms of a Recapitalization Agreement entered into on August 13, 2020 among us, the Trident V Funds, which are advised by Stone Point, and the Dowling Funds (the "Recapitalization Agreement"), we agreed to exchange a portion of our indirect interest in Northshore, the holding company that owns Atrium and Arden, for all of the Trident V Funds’ indirect interest in StarStone U.S. (the “Exchange Transaction”), which is described in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations."

Our interests in StarStone and Atrium are held through North Bay, which is a joint venture between us, the Trident V Funds and the Dowling Funds. As of December 31, 2020, we had an indirect 59.0% interest in North Bay and the Trident V Funds and the Dowling Funds owned 39.3% and 1.7%, respectively. North Bay owned 100% of StarStone Specialty Holdings Limited ("SSHL"), the holding company for the StarStone group, which included StarStone U.S. and StarStone International. North Bay also owned 92% of Northshore. North Bay also owns the preferred equity of three segregated cells within our wholly-owned subsidiary Fitzwilliam Insurance Limited (the “Fitzwilliam Cells”) that have provided reinsurance to StarStone and are considered part of StarStone International. Following the completion of the sale and recapitalization of StarStone U.S. and the Exchange Transaction, we now own 25.23% of Core Specialty on a fully diluted basis, which owns StarStone U.S., and 13.8% of Northshore, which continues to own Atrium and Arden. The Trident V Funds own 76.3% of Northshore, and the Dowling Funds own 0.4% of Core Specialty and 1.6% of Northshore. The Exchange Transaction had no impact on the ultimate ownership of SSHL, which continues to own StarStone International, with us, the Trident V Funds and the Dowling Funds retaining our and their prior ownership interests in SSHL of 59.0%, 39.3% and 1.7%, respectively.

In connection with the closing of the Exchange Transaction, we entered into amended and restated shareholders’ agreements with the Trident V Funds and the Dowling Funds with respect to our investment in SSHL and Northshore. With respect to SSHL, we have the right to designate three of five members of the SSHL board of directors and the Trident V Funds have the right to designate the other two members. The Trident V Funds also have certain customary rights as a minority shareholder to approve certain material matters and transactions. Each shareholder of SSHL must provide us and the Trident V Funds with a right of first offer to acquire its shares in SSHL if such shareholder wishes to sell them. Each shareholder will also have certain rights to participate in sales of SSHL shares by the other shareholders, and we have certain rights to cause the Trident V Funds and the Dowling Funds to sell their SSHL shares if we wish to sell control of SSHL or the StarStone International business.

Also pursuant to the terms of the shareholders’ agreement for SSHL, at any time after December 31, 2022, the Trident V Funds have the right to cause us to purchase their shares in SSHL at their fair market value, and the Dowling Funds have the right to participate in any such sale transaction initiated by the Trident V Funds. We would be entitled to pay the purchase price for such SSHL shares in cash or in unrestricted ordinary shares of Enstar that are then listed or admitted to trading on a national securities exchange. At any time after March 31, 2023, we will have the right to cause the Trident V Funds and the Dowling Funds to sell their shares in SSHL to us at their fair market value. We would be obligated to pay the purchase price for such SSHL shares in cash.

Pursuant to the terms of the shareholders’ agreement for Northshore, for so long as we own 50% or more of the Northshore shares we held upon the closing of the Exchange Transaction, we have the right to designate one member to the board of directors of Northshore and each of its material subsidiaries. Our shares in Northshore are subject to an 18-month restriction on transfer following the closing of the Exchange Transaction, after which the Trident V Funds have a right of first offer to acquire our shares in Northshore if we wish to sell them. We have certain rights to participate in sales of Northshore shares by the Trident V Funds, and the Trident V Funds have certain rights to cause us to sell our Northshore shares if the Trident V Funds wish to sell control of Northshore or the Atrium business. We, in partnership with StarStone's other shareholders, have previously completed transactions to provide capital support to StarStone in the form of:

(i) a contribution to its contributed surplus account and a loss portfolio transfer, effective October 1, 2018. To fund the transaction, the North Bay shareholders contributed an aggregate amount of $135.0 million to North Bay in proportion to their ownership interests. Trident’s proportionate contribution of $53.1 million was temporarily funded by North Bay and was reimbursed in the first quarter of 2019; and

(ii) a loss portfolio transfer, effective April 1, 2019, for which shareholders agreed to contribute an aggregate amount of $48.0 million.

In addition, Enstar has separately entered into a loss portfolio transfer and adverse development cover with StarStone effective October 1, 2019, whereby StarStone transferred $189.4 million in loss reserves and unearned premium to a wholly-owned Enstar subsidiary in exchange for premium of $189.4 million. Enstar also provided an additional $59.0 million adverse development cover in excess of the $189.4 million.

As of December 31, 2020 and December 31, 2019, the RNCI on our balance sheet relating to these Trident co-investment transactions was $350.2 million and $420.5 million, respectively.

As of December 31, 2020, we had the following additional relationships with Stone Point and its affiliates:

•Investments in funds (carried within other investments) managed by Stone Point, with respect to which we recognized net unrealized gains (losses);

•Investments in registered investment companies affiliated with entities owned by Trident or otherwise affiliated with Stone Point, with respect to which we recognized net unrealized gains (losses) and interest income;

•Separate accounts managed by Eagle Point Credit Management, PRIMA Capital Advisors and SKY Harbor Capital Management, which are affiliates of entities owned by Trident, with respect to which we incurred management fees;

•Investments in funds (carried within other investments) managed by Sound Point Capital, an entity in which Mr. Carey has an indirect minority ownership interest and serves as a director, with respect to which we recognized net unrealized gains (losses);

•Sound Point Capital has acted as collateral manager for certain of our direct investments in CLO debt and equity securities, with respect to which we recognized net unrealized gains (losses) and interest income;

•Marble Point Capital, which is an affiliate of an entity owned by Trident, has acted as collateral manager for certain of our direct investments in CLO debt and equity securities, with respect to which we recognized net unrealized gains (losses) and interest income;

•A separate account managed by Sound Point Capital, with respect to which we incurred management fees in prior periods;

•In the fourth quarter of 2018, we invested $25.0 million in Mitchell TopCo Holdings, the parent company of Mitchell International and Genex Services, as a co-investor alongside certain Trident funds; and

•In the second quarter of 2020, we invested $10.0 million in a 2 year senior secured unrated floating rate term loan facility with an extension option which was arranged and managed by Sound Point Capital. The facility's borrower, Amplify U.S. Inc., is a subsidiary of Evergreen (as defined below) and has used the proceeds to purchase AmTrust's preferred stock. The facility ranks senior to all other claims of the borrower, the purchased preferred stock and cash flows therefrom serve as collateral, and AmTrust has provided an unsecured guarantee for the facility. For further information on our relationships with Evergreen and AmTrust, refer to the AmTrust section below.

The following table presents the amounts included in our consolidated balance sheet related to our related party transactions with Stone Point and its affiliated entities:


	December 31, 2020		December 31, 2019

Short-term investments, AFS, at fair value	$	878	$	1,431
Fixed maturities, trading, at fair value	196,086		269,131
Fixed maturities, AFS, at fair value	227,397		160,303
Equities, at fair value	103,914		121,794
Other investments, at fair value:
Hedge funds	19,844		18,993
Fixed income funds	210,017		381,449

Private equity funds	37,262		34,858
CLO equities	38,658		32,560
CLO equity funds	166,523		87,509


Private Debt	27,016		16,312
Real estate fund	27,278		18,106
Total investments	1,054,873		1,142,446
Cash and cash equivalents	23,933		54,080
Other assets	403		10
Other liabilities	745		4,710
Net investment	$	1,078,464	$	1,191,826

The following table presents the amounts included in net earnings related to our related party transactions with Stone Point and its affiliated entities:


	2020		2019		2018
Net investment income	$	16,325	$	8,733	$	7,424
Net realized and unrealized gains (losses)	23,750		26,631		207
Total net earnings	$	40,075	$	35,364	$	7,631

KaylaRe

On December 15, 2016, KaylaRe completed an initial capital raise of $620.0 million. We originally owned 48.2% of KaylaRe's common shares and recorded our investment in KaylaRe using the equity method basis of accounting, pursuant to the conclusion that we were not required to consolidate following an analysis based on the guidance in ASC 810 - Consolidation.

On May 14, 2018, we completed a transaction to acquire all of the outstanding shares and warrants of KaylaRe, following the receipt of all required regulatory approvals. In consideration for the acquired shares and warrants of KaylaRe, we issued an aggregate of 2,007,017 ordinary shares, comprising 1,501,778 voting ordinary shares and 505,239 Series E non-voting ordinary shares to the shareholders of KaylaRe as follows: (i) 1,204,353 voting ordinary shares and 505,239 Series E Shares to a fund managed by Hillhouse Capital Management, Ltd.; (ii) 285,986 voting ordinary shares to Trident; and (iii) 11,439 voting ordinary shares to the minority shareholder. In addition, the Shareholders Agreement between Enstar and the other KaylaRe shareholders was effectively terminated. Effective May 14, 2018 we consolidated KaylaRe into our consolidated financial statements and any balances between KaylaRe and Enstar are now eliminated on consolidation. Refer to Note 3 - "Business Acquisitions" for additional information. Effective September 30, 2019, KaylaRe and KaylaRe Ltd. merged with Cavello Bay Reinsurance Limited, a wholly-owned subsidiary of the Company, with Cavello Bay Reinsurance Limited as the surviving company.

Our consolidated statement of earnings for the year ended December 31, 2018 included the following balances related to transactions between us and KaylaRe and KaylaRe Ltd. up until May 14, 2018, the date of acquisition:


	2018
Fee income due to Enstar Limited	$	1,453

Transactions under KaylaRe-StarStone QS:
Ceded premium earned	(52,651)
Net incurred losses	31,654
Acquisition costs	18,774




Total net earnings (loss)	$	(770)

HillhouseInvestment funds managed by Hillhouse Capital (defined below) collectively own 9.4% of Enstar’s voting ordinary shares. These funds also own non-voting ordinary shares and warrants to purchase additional non-voting ordinary shares, which together with their voting ordinary shares, represent 16.6% economic interest in Enstar. The warrants, which expire in April 2021, permit these funds to acquire 175,901 Series C Non-Voting Ordinary Shares for an exercise price of $115.00 per share, subject to certain adjustments. From February 2017 to February 2021, Jie Liu, a partner of AnglePoint (defined below), served on our Board.

We have made significant direct investments in funds (the "Hillhouse Funds") managed by Hillhouse Capital Management, Ltd. and Hillhouse Capital Advisors, Ltd. (together, "Hillhouse Capital") and AnglePoint Asset Management Ltd., an affiliate of Hillhouse Capital ("AnglePoint"). As of December 31, 2020, the carrying value (i.e., the net asset value) of our direct investment in the InRe Fund, L.P. (the "InRe Fund"), which is managed by AnglePoint, was $2.4 billion (December 31, 2019: $918.6 million). The growth in the fund for the year ended December 31, 2020 was generated by significant unrealized investment gains during the year and an increase in our subscription to the fund of $300.0 million in June 2020. The InRe Fund qualifies as a variable interest entity and our maximum exposure to loss is the amount of our investment in the fund, as disclosed in the table below. As of December 31, 2020, the InRe Fund's assets were invested (5)% in net short fixed income securities, 20% in North American equities, 67% in international equities and 18% in financing, derivatives and other items. The derivatives in the InRe Fund are used for both hedging and investment purposes. The InRe Fund utilizes prime brokerage borrowing facilities and has also securitized certain letters of credit relating to intragroup reinsurances. We do not provide any financial support to the InRe Fund. Funds that employ leverage through borrowings and derivatives can generate outsized returns but can also experience greater levels of volatility.

As of December 31, 2020 and 2019, our equity method investee, Enhanzed Re, had investments in a fund managed by AnglePoint, as set forth in the table below.

Our consolidated balance sheet as of December 31, 2020 and 2019 included the following balances related to transactions with Hillhouse Capital and AnglePoint (as applicable):


	2020			2019
Investments in funds managed by AnglePoint, held by Enhanzed Re	$	851,435		$	327,799
Our ownership percentage of Enhanzed Re	47.4		%	47.4		%
Our share of investments in funds managed by AnglePoint held by Enhanzed Re (through our equity method investment ownership)	$	403,580		$	155,377

Investment in other funds managed by AnglePoint and Hillhouse:
InRe Fund	$	2,365,158		$	918,633
Other funds	369,508			232,968
	$	2,734,666		$	1,151,601

We incurred management and performance fees of $394.0 million, which is deducted from the Hillhouse Funds' reported NAV, for the year ended December 31, 2020 in relation to the investment in funds managed by Hillhouse Capital and AnglePoint as described above.

On February 21, 2021, we entered into a Termination and Release Agreement with InRe Fund, Hillhouse Capital, AnglePoint, and certain of their affiliates to terminate certain relationships, primarily with respect to InRe Fund, and to work collaboratively to effectuate the smooth transition of these changes. Pursuant to the Termination

and Release Agreement, AnglePoint will cease to serve as the InRe Fund's investment manager on or prior to April 1, 2021 in connection with the intended purchase of AnglePoint’s Hong Kong affiliate (“AnglePoint HK”) by us or our designee from affiliates of Hillhouse Capital. As part of those transactions, AnglePoint will assign its investment management agreement with InRe Fund to AnglePoint HK. In connection with AnglePoint ceasing to serve as investment manager, affiliates of Hillhouse Capital agreed to a deduction of $100.0 million from amounts due to them from the InRe Fund and to waive their right to receive any performance fees that could have been earned for 2021. The Agreement also includes mutual releases of certain liabilities and obligations between Enstar and its affiliates on the one hand and Hillhouse and its affiliates on the other hand.

In the first quarter of 2021, as a result of the Termination and Release Agreement, we will re-evaluate our conclusions with regard to consolidation of the InRe Fund in accordance with the accounting for variable interest entities.

Monument Re

Monument Insurance Group Limited ("Monument Re") was established in October 2016 and Enstar has invested a total of $59.6 million in the common and preferred shares of Monument Re as of December 31, 2020 (December 31, 2019: $26.6 million). We own 20% of the common shares of Monument Re, as well as different classes of preferred shares which have fixed dividend yields, and which collectively represented a total economic interest of 23.0% as of December 31, 2020 (December 31, 2019: 23.5%). In connection with our investment in Monument Re, we entered into a Shareholders Agreement with the other shareholders and have accounted for our equity interest in Monument Re as an equity method investment since we have significant influence over its operating and financial policies.

On May 31, 2019, we completed the transfer of our remaining life assurance policies written by our wholly-owned subsidiary Alpha Insurance SA to a subsidiary of Monument Re. In this transaction, we transferred policy benefits for life and annuity contracts with a carrying value of €88.8 million (or $99.1 million) and total assets with a fair value of €91.1 million (or $101.6 million) to a subsidiary of Monument Re.

Our investment in the common and preferred shares of Monument Re, which is included in equity method investments on our consolidated balance sheet, as of December 31, 2020 and 2019 was $193.7 million and $60.6 million, respectively.

During the twelve months ended December 31, 2020 and 2019 our share of net earnings on our investment in Monument Re was $88.3 million and $19.8 million, respectively. In addition, we received director fees from Monument Re of less than $0.1 million in connection with one of our representatives serving on Monument Re's board of directors during the twelve months ended December 31, 2020.

Clear Spring (formerly SeaBright)

Effective January 1, 2017, we sold SeaBright Insurance Company (“SeaBright Insurance”) to Clear Spring PC Acquisition Corp., a subsidiary of Delaware Life Insurance Company ("Delaware Life"). Following the sale, SeaBright Insurance was capitalized with $56.0 million of equity, with Enstar retaining a 20% indirect equity interest in SeaBright Insurance. Subsequently, SeaBright Insurance was renamed Clear Spring Property and Casualty Company ("Clear Spring"). Effective December 30, 2020, we sold our remaining interest in Clear Spring to Delaware Life for $12.2 million and recorded a gain on sale of $0.6 million in the fourth quarter of 2020. As a result, Clear Spring was not a related party as of December 31, 2020.

Prior to the sale, we accounted for our equity interest in Clear Spring as an equity method investment as we had significant influence over its operating and financial policies. Our investment in the common shares of Clear Spring which is included in equity method investments on our consolidated balance sheet, as of December 31, 2020 and 2019 was $0 and $10.6 million, respectively.

During the twelve months ended December 31, 2020 and 2019 our share of net earnings on our investment in Clear Spring was $1.0 million and $0.6 million, respectively.

Effective January 1, 2017, StarStone National Insurance Company (“StarStone National”) entered into a ceding quota share treaty with Clear Spring pursuant to which Clear Spring reinsures 33.3% of core workers' compensation business written by StarStone National. This agreement was terminated as of December 31, 2018.

Effective January 1, 2017, we also entered into an assuming quota share treaty with Clear Spring pursuant to which an Enstar subsidiary reinsures 25% of all workers' compensation business written by Clear Spring. This is recorded as other activities.

As noted above, Clear Spring was not a related party as of December 31, 2020. Our consolidated balance sheet as of December 31, 2019 included the following balances between us and Clear Spring:


	2019
Balances under StarStone ceding quota share included, in assets or liabilities held-for-sale:
Reinsurance balances recoverable on paid and unpaid losses	$	22,812
Prepaid insurance premiums	51
Ceded payable	3,616
Ceded acquisition costs	21

Balances under assuming quota share:
Losses and LAE	6,135
Unearned reinsurance premiums	13
Funds held	8,611

Our consolidated statement of earnings for the years ended December 31, 2020, 2019 and 2018 included the following amounts between us and Clear Spring:


	2020		2019		2018
Transactions under StarStone ceding quota share, included in net earnings (loss) from discontinued operations:
Ceded premium earned	$	122	$	(14,994)	(29,520)
Net incurred losses and LAE	2,730		6,567		18,143
Acquisition costs	56		356		7,035

Transactions under assuming quota share:
Premium earned	(15)		3,749		7,380
Net incurred losses and LAE	1,014		(2,202)		(4,536)
Acquisition costs	11		(92)		(1,836)

Total net earnings (loss)	$	3,918	$	(6,616)	$	(3,334)

AmTrustIn November 2018, pursuant to a Subscription Agreement with Evergreen Parent L.P. ("Evergreen"), K-Z Evergreen, LLC and Trident Pine Acquisition LP ("Trident Pine"), we purchased equity in Evergreen in the aggregate amount of $200.0 million. Evergreen is an entity formed by private equity funds managed by Stone Point and the Karfunkel-Zyskind family that acquired the 45% of the issued and outstanding shares of common stock of AmTrust that the Karfunkel-Zyskind Family and certain of its affiliates and related parties did not already own or control. The equity interest was in the form of equity securities issued at the same price and in the same proportion as the equity interest purchased by Trident Pine. In a second transaction in December 2019, Enstar acquired an additional $25.9 million of Evergreen securities from another investor.Following the closing of the second transaction, Enstar owns 8.5% of the equity interest in Evergreen and Trident Pine owns 21.8%. Evergreen owns all of the equity interest in AmTrust. In addition, upon the successful closing of the transaction we received a fee of $3.3 million, half of which was received upon closing, and the other half was received on the first anniversary of the closing. The fee was recorded in full in other income within our consolidated statements of earnings for the year ended December 31, 2018.Our indirect investment in the shares of AmTrust, carried in equities on our consolidated balance sheet, as of December 31, 2020 and 2019 was $230.3 million and $240.1 million, respectively.

The following table presents the amounts included in net earnings related to our related party transactions with AmTrust:


	2020		2019		2018
Net investment income	$	7,365	$	7,667	$	299
Net realized and unrealized gains	(11,183)		10,086		—
Total net earnings	$	(3,818)	$	17,753	$	299

Citco

In June 2018, we made a $50.0 million indirect investment in the shares of Citco III Limited ("Citco"), a fund administrator with global operations. As of December 31, 2020, we owned 31.9% of the common shares in HH CTCO Holdings Limited, which in turn owns 15.4% of the convertible preferred shares, amounting to a 6.2% interest in the total equity of Citco. Pursuant to an investment agreement and in consideration for participation therein, a related party of Hillhouse Capital provided us with investment support. In a private transaction that preceded our co-investment opportunity, certain Citco shareholders, including Trident, agreed to sell all or a portion of their interests in Citco. As of December 31, 2020, Trident owned 3.4% interest in Citco. Mr. Carey currently serves as an observer to the board of directors of Citco in connection with Trident's investment therein.

Our indirect investment in the shares of Citco, which is included in equity method investments on our consolidated balance sheet, as of December 31, 2020 and 2019 was $53.0 million and $51.7 million, respectively.

During the twelve months ended December 31, 2020 and 2019 our share of net earnings on our indirect investment in Citco was $2.2 million and $2.7 million, respectively.

Enhanzed Re

Enhanzed Re is a joint venture between Enstar, Allianz SE ("Allianz") and Hillhouse Capital that was capitalized in December 2018. Enhanzed Re is a Bermuda-based Class 4 and Class E reinsurer and will reinsure life, Non-life Run-off, and property and casualty insurance business, initially sourced from Allianz and Enstar. Enstar, Allianz and Hillhouse Capital affiliates have made equity investment commitments in the aggregate of $470.0 million to Enhanzed Re. Enstar owns 47.4% of the entity, Allianz owns 24.9%, and an affiliate of Hillhouse Capital owns 27.7%. As of December 31, 2020, Enstar contributed $154.1 million of its total capital commitment to Enhanzed Re and had an uncalled amount of $68.7 million. We have accounted for our equity interest in Enhanzed Re as an equity method investment as we have significant influence over its operating and financial policies.

Enstar acts as the (re)insurance manager for Enhanzed Re, for which it receives fee income recorded within fees and commission income, AnglePoint acts as the primary investment manager, and an affiliate of Allianz provides investment management services. Enhanzed Re writes business from affiliates of its operating sponsors, Allianz SE and Enstar. It also underwrites other business to maximize diversification by risk and geography.

Our investment in the common shares of Enhanzed Re, which is included in equity method investments on our consolidated balance sheet, as of December 31, 2020 and 2019 was $330.3 million and $182.9 million, respectively.

During the twelve months ended December 31, 2020 and 2019 our share of net earnings on our investment in Enhanzed Re was $147.3 million and $28.9 million, respectively.

We have ceded 10% of the Zurich and AXA transactions, as discussed in Note 4 - "Significant New Business," to Enhanzed Re on the same terms and conditions as those received by Enstar.

During the year ended December 31, 2020, one of our UK-based Non-life Run-off subsidiaries ceded $137.0 million of net loss reserves to Enhanzed Re. The reinsurance is on a funds held basis with fixed crediting rates.

Our consolidated balance sheet as of December 31, 2020 and 2019 included the following balances between us and Enhanzed Re:


	2020		2019
Balances under ceding quota share:
Reinsurance balances recoverable	$	208,379	$	59,601
Funds held	193,981		50,089
Insurance balances payables	1,276		1,443

Other assets	730		1,033

Our consolidated statement of earnings for the years ended December 31, 2020 and 2019 included the following amounts between us and Enhanzed Re:


	2020		2019
Amounts under ceding quota share:
Ceded premium earned	$	(391)	$	—
Net incurred losses and LAE	(5,977)		—
Acquisition costs	169		73
Net investment income	(4,272)		—
Net realized and unrealized gains	(740)		—
Other income	2,617		—
Fees and commission income	572		749
Total Net earnings	$	(8,022)	$	822

Change in unrealized gains (losses) on AFS investments	$	(2,729)	$	—

Core Specialty

Following the sale and recapitalization of StarStone U.S. as described in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations," our investment in the common shares of Core Specialty, which is included in equity method investments on our consolidated balance sheet was $235.0 million as of December 31, 2020.

In connection with the sale and recapitalization of StarStone U.S. we entered into an LPT and ADC reinsurance agreement with respect to StarStone U.S.’ legacy reserves. Concurrent with the closing of the LPT and ADC reinsurance agreement, we entered into an ASA with StarStone U.S., through which one of our wholly-owned subsidiaries was appointed as an independent contractor to provide certain administrative services covering the business we assumed from StarStone U.S. through the LPT and ADC reinsurance agreement.

In addition, concurrent with the sale of StarStone U.S. to Core Specialty, one of our wholly-owned subsidiaries entered into a TSA with Core Specialty through which our subsidiary and Core Specialty agreed to provide certain transitional services to each other relating to the StarStone U.S. businesses, for a specified period of time.

On completion of the sale and recapitalization of StarStone U.S. on November 30, 2020, we received $235.0 million of Core Specialty shares and $51.5 million of cash. Subsequently, the cash component of the consideration has been determined to be $47.0 million. The surplus of $4.5 million is repayable to Core Specialty and is recorded within other liabilities.

Furthermore, there are existing reinsurance agreements whereby (i) certain of our subsidiaries provide reinsurance protection to StarStone U.S. ("the assuming reinsurances") and (ii) StarStone U.S. provides reinsurance protection to certain of our subsidiaries ("the ceding reinsurances"). These arrangements remain in place.

Our consolidated balance sheet as of December 31, 2020 included the following balances between us and Core Specialty:


	2020
Balances under assuming quota share, LPT and ADC reinsurances:
Funds held by reinsured companies	$	58,086
Other assets	38,846
Losses and loss adjustment expenses	682,637
Insurance and reinsurance balances payable	24,806
Other liabilities	5,003

Balances under ceding reinsurances:
Reinsurance balances recoverable on paid and unpaid losses	1,736

Balances under service agreements:
Other assets	6,727
Other liabilities	328

Balances under sale and recapitalization agreement:
Other liabilities	4,512

Our consolidated statement of earnings for the year ended December 31, 2020 included the following amounts between us and Core Specialty:


	2020
Transactions under assuming quota share, LPT and ADC reinsurances:
Net premiums earned	$	76
Net incurred losses and loss adjustment expenses	(1,223)
Acquisition costs	458

Transactions under service agreements:
Fees and commission income	4,004

Total net earnings	$	3,315

Dividend Restrictions and Statutory Financial Information

12 Months Ended

Dec. 31, 2020

Dividend Restrictions and Statutory Financial Information

22. DIVIDEND RESTRICTIONS AND STATUTORY FINANCIAL INFORMATION

Parent Company Dividend Restrictions

There were no significant restrictions on the Parent Company's ability to pay dividends from retained earnings as of December 31, 2020. Bermuda law permits the payment of dividends if (i) we are not, or would not be after payment, unable to pay our liabilities as they become due and (ii) the realizable value of our assets is in excess of our liabilities after taking such payment into account. We have not historically declared a dividend on our ordinary shares. The issuance of our Series D and E Preferred Shares have resulted in the declaration of dividends. Holders of Series D and Series E Preferred Shares are entitled to receive, only when, as and if declared, non-cumulative cash dividends, paid quarterly in arrears on the 1st day of March, June, September and December of each year of 7.0% per annum. Refer to Note 17 - "Shareholders' Equity" for details regarding dividends on preferred shares.

The Bermuda Monetary Authority ("BMA") acts as group supervisor to Enstar. On an annual basis, we are required to file group statutory financial statements, a group statutory financial return, a group capital and solvency return, audited group financial statements and a Group Solvency Self-Assessment ("GSSA") with the BMA. The

GSSA is designed to document our perspective on the capital resources necessary to achieve our business strategies and remain solvent, and to provide the BMA with insights on our risk management, governance procedures and documentation related to this process. We are required to maintain available group statutory capital and surplus in an amount that is at least equal to the group enhanced capital requirement ("Group ECR"). The BMA has also established a group target capital level equal to 120% of the Group ECR. We are in compliance with these requirements.

Our ability to pay dividends to our shareholders is dependent upon the ability of our (re)insurance subsidiaries to distribute capital and pay dividends to us. Our (re)insurance subsidiaries are subject to certain regulatory restrictions on the distribution of capital and payment of dividends in the jurisdictions in which they operate, as described below. The restrictions are generally based on net income or levels of capital and surplus as determined in accordance with the relevant statutory accounting practices. Failure of these subsidiaries to meet their applicable regulatory requirements could result in restrictions on any distributions of capital or retained earnings or stricter regulatory oversight of the subsidiaries.

Our ability to pay dividends and make other forms of distributions may also be limited by repayment obligations and financial covenants in our outstanding loan facility agreements.

Subsidiary Statutory Financial Information and Dividend Restrictions

Our (re)insurance subsidiaries prepare their statutory financial statements in accordance with statutory accounting practices prescribed or permitted by local regulators. Statutory and local accounting differs from U.S. GAAP, including in the treatment of investments, acquisition costs and deferred income taxes, amongst other items.

The statutory capital and surplus amounts for the years ended December 31, 2020 and 2019 and statutory net income amounts for the years ended December 31, 2020, 2019 and 2018 for our (re)insurance subsidiaries based in Bermuda, the United Kingdom, Australia, the United States and Continental Europe are summarized in the table below which includes information relating to acquisitions from the year of acquisition:


	Statutory Capital and Surplus
	Required				Actual				Statutory Income
	2020		2019		2020		2019		2020		2019		2018
Bermuda	$	2,711,687	$	2,138,395	$	5,565,429	$	4,016,663	$	1,850,913	$	643,683	$	29,486
U.K.	803,685		837,104		1,224,208		1,532,751		43,219		154,644		(52,936)
U.S.	185,904		364,507		554,339		861,379		(67,477)		121,406		(75,005)
Europe	95,746		94,334		214,115		229,344		(983)		11,816		(17,611)
Australia	18,858		18,110		58,531		37,815		(1,722)		4,847		1,761

As of December 31, 2020, the total amount of net assets of our consolidated subsidiaries that were restricted was $3.8 billion.

Certain material aspects of these laws and regulations as they relate to solvency, dividends and capital and surplus are summarized below.

Bermuda

Our Bermuda-based (re)insurance subsidiaries are registered under the Insurance Act 1978 of Bermuda and related regulations, as amended (the "Insurance Act"). The Insurance Act imposes certain solvency and liquidity standards and auditing and reporting requirements and grants the BMA powers to supervise, investigate, require information and the production of documents and intervene in the affairs of insurance companies.

The Insurance Act requires that our Bermuda-based (re)insurance subsidiaries maintain certain solvency and liquidity standards. The minimum liquidity ratio requires that the value of relevant assets not be less than 75% of the amount of relevant liabilities. The minimum solvency margin, which varies depending on the class of the insurer, is determined as a percentage of either net reserves for losses and LAE or premiums. Our Bermuda subsidiaries with commercial insurance licenses are required to maintain a minimum statutory capital and surplus (Enhanced Capital Requirement or "ECR") at least equal to the greater of a minimum solvency margin or the Bermuda Solvency Capital Requirement ("BSCR"). The BSCR is calculated based on a standardized risk-based capital model as provided by the BMA.

Each of our regulated Bermuda subsidiaries would be prohibited from declaring or paying any dividends if it were in breach of its minimum solvency margin or liquidity ratio or if the declaration or payment of such dividends

would cause it to fail to meet such margin or ratio. In addition, each of our regulated Bermuda subsidiaries is prohibited, without the prior approval of the BMA, from reducing by 15% or more its total statutory capital, or from reducing by 25% of more its total statutory capital and surplus, as set out in its previous year’s statutory financial statements. Our Bermuda insurance companies that are in run-off are required to seek BMA approval for any dividends or distributions.

As of December 31, 2020 and 2019, each of our Bermuda-based (re)insurance subsidiaries exceeded their respective minimum solvency and liquidity requirements. The Bermuda (re)insurance subsidiaries in aggregate exceeded minimum solvency requirements by $2.9 billion as of December 31, 2020 (2019: $1.9 billion) and were in compliance with their liquidity requirements.

United Kingdom

U.K. Insurance Companies (non-Lloyd's)

Our U.K. based insurance subsidiaries are regulated by the U.K. Prudential Regulatory Authority (the "PRA") and the Financial Conduct Authority (the "FCA", together with the PRA, the "U.K. Regulator").

Our U.K.-based insurance subsidiaries are required to maintain adequate financial resources in accordance with the requirements of the U.K. Regulator. Insurers must comply with a Solvency Capital Requirement ("SCR"), which is calculated using either the Solvency II standard formula or a bespoke internal model. Our non-Lloyd's U.K. companies use the standard formula for determining compliance with the SCR.

The calculation of the minimum capital resources requirements in any particular case depends on, among other things, the type and amount of insurance business written and claims paid by the insurance company. As of December 31, 2020 and 2019, all of our U.K. insurance subsidiaries maintained capital in excess of the minimum capital resources requirements and complied with the relevant U.K. Regulator requirements. Our U.K.-based insurance subsidiaries, including our Lloyd's Syndicates described below, in aggregate, maintained capital in excess of the minimum capital resources requirements by $420.5 million and $695.6 million as of December 31, 2020 and 2019, respectively.

The U.K. Regulator’s rules require our U.K. insurance subsidiaries to obtain regulatory approval for any proposed or actual payment of a dividend. The U.K. Regulator uses the SCR, among other tests, when assessing requests to make distributions.

Lloyd’s

As of December 31, 2020, we participated in the Lloyd’s market through our interests in: (i) Atrium’s Syndicate 609, which is managed by Atrium Underwriters Limited, a Lloyd's managing agent; (ii) StarStone’s Syndicate 1301, which is managed by StarStone Underwriting Limited ("SUL"), a Lloyd’s managing agent; and (iii) Syndicate 2008, a wholly aligned syndicate that has permission to underwrite RITC business and other run-off or discontinued business type transactions with other Lloyd’s syndicates. We participated on each of the three syndicates through a single, wholly owned Lloyd’s corporate member. SUL serves as managing agent for Syndicate 2008. On November 17, 2020, we announced an agreement to sell SUL, together with the right to operate StarStone's Syndicate 1301; and on January 1, 2021, we sold the Atrium business. These transactions are discussed further in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations."

The underwriting capacity of a member of Lloyd’s is supported by providing Funds at Lloyd’s, as described in Note 6 - "Investments". Business plans, including maximum underwriting capacity, for Lloyd’s syndicates requires annual approval by the Lloyd’s Franchise Board, which may require changes to any business plan or additional capital to support underwriting plans.

The Lloyd’s market has applied the Solvency II internal model under Lloyd’s supervision, and our Lloyd’s operations are required to meet Solvency II standards. Lloyd's has the approval of the PRA to use its internal model under the Solvency II regime.

United States

Our U.S. Non-life Run-off (re)insurance subsidiaries are subject to the insurance laws and regulations of the states in which they are domiciled, licensed and/or eligible to conduct business. These laws restrict the amount of dividends the subsidiaries can pay to us. The restrictions are generally based on statutory net income and/or certain levels of statutory surplus as determined in accordance with the relevant statutory accounting requirements of the individual domiciliary states or states in which any of the (re)insurance subsidiaries are commercially domiciled. Generally, prior regulatory approval must be obtained before an insurer may make a distribution above a specified

level.

The U.S. (re)insurance subsidiaries are also required to maintain minimum levels of solvency and liquidity as determined by law, and to comply with Risk-Based Capital ("RBC") requirements and licensing rules as specified by the National Association of Insurance Commissioners ("NAIC"). RBC is used to evaluate the adequacy of capital and surplus maintained by our U.S. (re)insurance subsidiaries in relation to three major risk areas associated with: (i) asset risk; (ii) insurance risk and (iii) other risks. For all of our U.S. (re)insurance subsidiaries, with the exception of one subsidiary which has a permitted accounting practice to treat an adverse development cover reinsurance agreement as prospective reinsurance, there are no prescribed or permitted statutory accounting practices that differ significantly from the statutory accounting principles established by NAIC.

As of December 31, 2020, all of our U.S. non-life (re)insurance subsidiaries exceeded their required levels of risk-based capital. On an aggregate basis, our U.S. non-life (re)insurance subsidiaries exceeded their minimum levels of risk-based capital as of December 31, 2020 by $362.2 million (2019: $488.3 million).

Europe

Our Liechtenstein insurance subsidiary (StarStone Insurance SE) is regulated by the Liechtenstein Financial Market Authority ("FMA") pursuant to the Liechtenstein Insurance Supervisory Act. This subsidiary is obligated to maintain a minimum solvency margin based on the Solvency II regulations. As of December 31, 2020, this subsidiary exceeded the Solvency II requirements by $97.6 million (2019: $119.0 million). The amount of dividends that this subsidiary is permitted to distribute is restricted to freely distributable reserves, which consist of retained earnings, the current year profit and legal reserves. Any dividend exceeding the current year profit requires the FMA’s approval. Solvency and capital requirements for this subsidiary are based on the Solvency II framework and must continue to be met following any distribution.

Australia

The Company’s Australian insurance subsidiary is regulated and subject to prudential supervision by the Australian Prudential Regulation Authority (“APRA”). APRA is the primary regulatory body responsible for regulating compliance with the Insurance Act 1973. APRA’s prudential standards require that all insurers maintain and meet prescribed capital adequacy requirements designed to ensure that insurers to meet their insurance obligations under a wide range of scenarios.

A run-off insurer must obtain APRA’s written consent prior to making any capital releases, including any payment of dividends, not from current year profits. The Company’s insurance subsidiary must provide APRA a valuation prepared by its Appointed Actuary that demonstrates that the tangible assets of the insurer, after the proposed capital reduction, are sufficient to cover its insurance liabilities.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

23. COMMITMENTS AND CONTINGENCIES

Concentration of Credit Risk

We believe that there are no significant concentrations of credit risk associated with our cash and cash equivalents, fixed maturity investments, or other investments. Our cash and investments are managed pursuant to guidelines that follow prudent standards of diversification and liquidity, and limit the allowable holdings of a single issue and issuers. We are also subject to custodial credit risk on our investments, which we manage by diversifying our holdings amongst large financial institutions that are highly regulated.

We have exposure to credit risk on certain of our assets pledged to ceding companies under insurance contracts. In addition, we are potentially exposed should any insurance intermediaries be unable to fulfill their contractual obligations with respect to payments of balances owed to and by us.

Credit risk exists in relation to (re)insurance balances recoverable on paid and unpaid losses. We remain liable to the extent that counterparties do not meet their contractual obligations and, therefore, we evaluate and monitor concentration of credit risk among our (re)insurers.

We are also subject to credit risk in relation to funds held by reinsured companies. Under funds held arrangements, the reinsured company has retained funds that would otherwise have been remitted to our reinsurance subsidiaries. The funds may be placed into trust or subject to other security arrangements. However,

we generally have the contractual ability to offset any shortfall in the payment of the funds held balances with amounts owed by us. As of December 31, 2020, we had a significant funds held concentration of $955.0 million to one reinsured company which has financial strength credit ratings of A+ from A.M. Best and AA from S&P.

We limit the amount of credit exposure to any one counterparty and none of our counterparty credit exposures, excluding U.S. government instruments and the counterparty noted above, exceeded 10% of shareholders’ equity as of December 31, 2020. Our credit exposure to the U.S. government was $1.4 billion as of December 31, 2020.

Legal Proceedings

We are, from time to time, involved in various legal proceedings in the ordinary course of business, including litigation and arbitration regarding claims. Estimated losses relating to claims arising in the ordinary course of business, including the anticipated outcome of any pending arbitration or litigation are included in the liability for losses and LAE in our consolidated balance sheets. In addition to claims litigation, we may be subject to other lawsuits and regulatory actions in the normal course of business, which may involve, among other things, allegations of underwriting errors or omissions, employment claims or regulatory activity. We do not believe that the resolution of any currently pending legal proceedings, either individually or taken as a whole, will have a material effect on our business, results of operations or financial condition. We anticipate that, similar to the rest of the (re)insurance industry, we will continue to be subject to litigation and arbitration proceedings in the ordinary course of business, including litigation generally related to the scope of coverage with respect to asbestos and environmental and other claims.

Unfunded Investment Commitments

As of December 31, 2020, we had unfunded commitments of $975.5 million to other investments, $68.7 million to equity method investments and $5.0 million to fixed maturity investments.

Guarantees

As of December 31, 2020 and 2019, parental guarantees and capital instruments supporting subsidiaries' insurance obligations were $1.5 billion and $1.0 billion, respectively. We also guarantee the Junior Subordinated Notes and the FAL facility, which are described in Note 15 - "Debt Obligations and Credit Facilities."

Redeemable Noncontrolling Interest

We have the right to purchase the RNCI interests from the RNCI holders at certain times in the future (each such right, a "call right") and the RNCI holders have the right to sell their RNCI interests to us at certain times in the future (each such right, a "put right"). Pursuant to the Exchange Transaction described in Note 21 - "Related Party Transactions" we exchanged a portion of our indirect interest in Northshore, the holding company that owns Atrium and Arden, for all of the Trident V Funds' indirect interest in StarStone U.S. on January 1, 2021. Following the closing of the Exchange Transaction, we have maintained a call right over the portion of SSHL owned by the Trident V Funds and the Dowling Funds, and they will maintain put rights to transfer those interests to us.

Leases

We have recognized a right-of-use asset and an offsetting lease liability on our consolidated balance sheets, relating primarily to office space and facilities that we have leased to conduct our business operations. On an ongoing basis we determine whether an arrangement is a lease or contains a lease at inception and also complete an assessment to determine the classification of each lease as either a finance lease or an operating lease. Our leases are all currently classified as operating leases.

Our leases have remaining lease terms of one year to 36 years, some of which include options to extend the lease term for up to five years and some of which include options to terminate the lease within one year. We consider these options in determining the lease term used to establish our right-of-use assets and lease liabilities. Renewal options that we believe we are likely to exercise are considered when determining lease terms. Our lease agreements do not contain any material residual value guarantees or material restrictive covenants.

Since a majority of our leases do not provide an implicit discount rate, we use our collateralized incremental borrowing rate in determining the present value of lease payments.

The table below provides the lease cost and other information relating to our operating leases for the years ended December 31, 2020 and 2019:


	2020			2019
Lease cost:
Operating lease cost	$	12,720		$	13,627
Short-term lease cost(1)	246			—
Total lease cost	12,966			13,627
Sub-lease income(2)	(553)			(542)
Total net lease cost	$	12,413		$	13,085

Other information:
Operating cash paid for amounts included in the measurement of lease liabilities	$	13,421		$	11,129
Non-cash activity: right-of-use assets relating to leases	295			57,536

Weighted-average remaining lease term	6.1 years			6.3 years
Weighted-average discount rate	6.5		%	6.3		%

(1) Leases with an initial lease term of twelve months or less are not recognized within our consolidated balance sheets.

(2) Sub-lease income consists of rental income received from third parties to whom we have sub-leased some of our leased office spaces and is included within other income in our consolidated statements of earnings.

Lease expense for the year ended December 31, 2018 was $11.3 million, relating to office space and facilities that we leased to conduct our business operations.

The table below provides a summary of the operating leases recorded on our consolidated balance sheets for the years ended December 31, 2020 and 2019:


	Balance sheet classification	2020		2019
Right-of-use assets (1) (2)	Other assets	$	32,297	$	46,747
Current lease liabilities (2)	Other liabilities	7,959		11,403
Non-current lease liabilities (2)	Other liabilities	27,064		34,785

(1) Following our decision to put the StarStone International operations into orderly run-off effective June 10, 2020, we recorded total impairment charges of $3.5 million on the right-of-use assets relating to certain StarStone International operating leases as of December 31, 2020.

(2) The right-of-use assets and the total lease liability balances exclude balances of $1.0 million and $0.8 million respectively, related to Atrium which have been reclassified to held-for-sale balances on our consolidated balance sheet as of December 31, 2020.

The table below provides a summary of the contractual maturities of our operating lease liabilities:



	2021		2022	2023	2024	2025	2026 and beyond	Total lease payments	Less: Imputed interest	Present value of lease liabilities
Contractual maturities	$	9,774	8,099	7,267	5,561	4,534	8,577	43,812	(8,789)	$	35,023

Segment Information

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Segment Information

24. SEGMENT INFORMATION

We have three reportable segments of business that are each managed, operated and separately reported: (i) Non-life Run-off; (ii) Atrium; and (iii) StarStone. Our other activities, which do not qualify as a reportable segment, include our corporate expenses, debt servicing costs, holding company income and expenses, foreign exchange and other miscellaneous items. These segments are described in Note 1 - "Description of Business."

As discussed in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations," the strategic transactions related to our Atrium and StarStone segments will enable us to focus on our core Non-life Run-off business. We will review and assess our segment structure in 2021 to reflect the changes to the StarStone and Atrium segments in the fourth quarter of 2020 and the first quarter of 2021, respectively.

The following tables set forth selected and consolidated statement of earnings results by segment for the years ended December 31, 2020, 2019, and 2018:


	2020
	Non-life Run-off		Atrium			StarStone			Other		Total
Gross premiums written	$	5,191	$	206,656		$	326,695		$	13,441	$	551,983

Net premiums written	$	2,987	$	183,194		$	233,202		$	13,441	$	432,824

Net premiums earned	$	58,695	$	175,393		$	318,115		$	19,889	$	572,092
Net incurred losses and LAE	(44,995)		(87,226)			(266,738)			(16,967)		(415,926)

Acquisition costs	(20,177)		(59,611)			(90,797)			(435)		(171,020)
Operating expenses	(200,990)		(13,078)			(81,853)			—		(295,921)
Underwriting income (loss)	(207,467)		15,478			(121,273)			2,487		(310,775)
Net investment income	282,048		5,542			27,443			(12,216)		302,817
Net realized and unrealized gains	1,627,526		4,165			10,328			—		1,642,019
Fees and commission income	19,462		22,984			—			—		42,446
Other income (losses)	99,940		131			3,734			(2,673)		101,132
Corporate expenses	(97,727)		(21,522)			(42,011)			(44,298)		(205,558)
Interest income (expense)	(67,195)		—			(2,110)			9,997		(59,308)
Net foreign exchange gains (losses)	(13,214)		4,327			(10,140)			2,634		(16,393)


EARNINGS (LOSS) BEFORE INCOME TAXES	1,643,373		31,105			(134,029)			(44,069)		1,496,380
Income tax expense	(17,412)		(4,122)			(902)			(1,391)		(23,827)
Earnings from equity method investments	238,569		—			—			—		238,569
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	1,864,530		26,983			(134,931)			(45,460)		1,711,122
Net earnings from discontinued operations, net of income taxes	—		—			16,251			—		16,251
NET EARNINGS (LOSS)	1,864,530		26,983			(118,680)			(45,460)		1,727,373
Net (earnings) loss attributable to noncontrolling interest	1,597		(11,059)			37,133			—		27,671
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	1,866,127		15,924			(81,547)			(45,460)		1,755,044
Dividends on preferred shares	—		—			—			(35,700)		(35,700)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$	1,866,127	$	15,924		$	(81,547)		$	(81,160)	$	1,719,344

Underwriting ratios:
Loss ratio			49.7		%	83.8		%
Acquisition expense ratio			34.0		%	28.5		%
Operating expense ratio			7.5		%	25.8		%
Combined ratio			91.2		%	138.1		%


	2019
	Non-life Run-off		Atrium			StarStone			Other		Total
Gross premiums written	$	(25,069)	$	192,373		$	472,815		$	18,534	$	658,653

Net premiums written	$	(25,338)	$	172,356		$	379,523		$	18,512	$	545,053

Net premiums earned	$	168,496	$	164,059		$	451,112		$	20,380	$	804,047
Net incurred losses and LAE	(51,625)		(77,276)			(469,240)			(16,038)		(614,179)

Acquisition costs	(73,642)		(56,956)			(109,369)			(642)		(240,609)
Operating expenses	(199,756)		(14,452)			(60,627)			—		(274,835)
Underwriting income (loss)	(156,527)		15,375			(188,124)			3,700		(325,576)
Net investment income	275,236		7,049			34,396			(8,410)		308,271
Net realized and unrealized gains	968,350		6,195			31,572			5,849		1,011,966
Fees and commission income	18,293		10,160			—			—		28,453
Other income	34,809		140			329			1,792		37,070
Corporate expenses	(70,689)		(13,825)			(7,790)			(45,945)		(138,249)
Interest income (expense)	(62,055)		—			(475)			9,989		(52,541)
Net foreign exchange gains (losses)	9,918		(504)			(1,505)			3		7,912


EARNINGS (LOSS) BEFORE INCOME TAXES	1,017,335		24,590			(131,597)			(33,022)		877,306
Income tax expense	(7,250)		(4,033)			(1,004)			(85)		(12,372)
Earnings (losses) from equity method investments	56,128		—			(218)			—		55,910
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	1,066,213		20,557			(132,819)			(33,107)		920,844
Net earnings from discontinued operations, net of income taxes	—		—			7,375			—		7,375
NET EARNINGS (LOSS)	1,066,213		20,557			(125,444)			(33,107)		928,219
Net (earnings) loss attributable to noncontrolling interest	(6,409)		(8,432)			24,711			—		9,870
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	1,059,804		12,125			(100,733)			(33,107)		938,089
Dividends on preferred shares	—		—			—			(35,914)		(35,914)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$	1,059,804	$	12,125		$	(100,733)		$	(69,021)	$	902,175

Underwriting ratios:
Loss ratio			47.1		%	104.0		%
Acquisition expense ratio			34.7		%	24.2		%
Operating expense ratio			8.8		%	13.5		%
Combined ratio			90.6		%	141.7		%


	2018
	Non-life Run-off		Atrium			StarStone			Other		Total
Gross premiums written	$	(8,910)	$	171,494		$	622,570		$	32,378	$	817,532

Net premiums written	$	(9,217)	$	153,488		$	478,009		$	32,067	$	654,347

Net premiums earned	$	9,427	$	146,315		$	515,163		$	24,874	$	695,779
Net incurred losses and LAE	306,067		(69,810)			(543,080)			(16,899)		(323,722)

Acquisition costs	(4,006)		(50,646)			(120,517)			(2,686)		(177,855)
Operating expenses	(158,731)		(17,777)			(98,137)			—		(274,645)
Underwriting income (loss)	152,757		8,082			(246,571)			5,289		(80,443)
Net investment income	226,287		5,686			27,000			2,725		261,698
Net realized and unrealized losses	(381,712)		(3,251)			(12,320)			(10,249)		(407,532)
Fees and commission income	16,466		18,622			—			—		35,088
Other income (losses)	35,978		162			(550)			(1,517)		34,073
Corporate expenses	(39,093)		(6,921)			—			(28,127)		(74,141)
Interest income (expense)	(30,616)		—			(103)			5,023		(25,696)
Net foreign exchange gains (losses)	2,534		(3,394)			(2,832)			1,048		(2,644)


EARNINGS (LOSS) BEFORE INCOME TAXES	(17,399)		18,986			(235,376)			(25,808)		(259,597)
Income tax benefit (expense)	3,581		(3,732)			3,892			(52)		3,689
Earnings from equity method investments	42,147		—			—			—		42,147
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	28,329		15,254			(231,484)			(25,860)		(213,761)
Net earnings from discontinued operations, net of income taxes	—		—			1,489			—		1,489
NET EARNINGS (LOSS)	28,329		15,254			(229,995)			(25,860)		(212,272)
Net (earnings) loss attributable to noncontrolling interest	(3,107)		(6,257)			71,415			—		62,051
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	25,222		8,997			(158,580)			(25,860)		(150,221)
Dividend on preferred shares	—		—			—			(12,133)		(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$	25,222	$	8,997		$	(158,580)		$	(37,993)	$	(162,354)

Underwriting ratios:
Loss ratio			47.7		%	105.4		%
Acquisition expense ratio			34.6		%	23.4		%
Operating expense ratio			12.2		%	19.1		%
Combined ratio			94.5		%	147.9		%

Gross Premiums Written by Geographical Area

The following table summarizes our gross premiums written for the year ended December 31, 2020 by geographic area. Geographic distribution in future years is subject to variation based upon market conditions and business strategies.


	Non-life Run-off			Atrium			StarStone			Other			Total
	Total		%	Total		%	Total		%	Total		%	Total		%
	(In thousands of U.S. dollars, except percentages)
United States	$	4,969	95.7	$	103,411	50.1	$	61,104	18.7	$	13,441	100.0	$	182,925	33.2
United Kingdom	(229)		(4.4)	14,054		6.8	105,057		32.2	—		—	118,882		21.5
Europe	1,615		31.1	19,705		9.5	62,181		19.0	—		—	83,501		15.1
Asia	—		—	7,834		3.8	60,262		18.4	—		—	68,096		12.3
Rest of World	(1,164)		(22.4)	61,652		29.8	38,091		11.7	—		—	98,579		17.9
Total	$	5,191	100.0	$	206,656	100.0	$	326,695	100.0	$	13,441	100.0	$	551,983	100.0

Assets by Segment

Invested assets are managed on a subsidiary by subsidiary basis, and investment income and realized and unrealized gains (losses) on investments are recognized in each segment as earned. Our total assets as of December 31, 2020 and 2019 by segment and for our other activities were as follows:


	2020		2019
Assets by Segment:
Non-life Run-off (1)	$	19,062,400	$	15,775,409
Atrium (2)	615,778		580,405
StarStone	2,583,247		3,985,137
Other	(614,141)		(514,852)
Total assets	$	21,647,284	$	19,826,099

(1) The total assets within the Non-life Run-off segment include assets of $95.5 million related to Arden's operations that have been included within Northshore's held-for-sale assets in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations" and Discontinued Operations."

(2) The total assets within the Atrium segment are all included within Northshore's held-for-sale assets in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations".

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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Quarterly Financial Information Disclosure [Abstract]

Unaudited Condensed Quarterly Financial Data

12 Months Ended

Dec. 31, 2020

Unaudited Condensed Quarterly Financial Data

25. UNAUDITED CONDENSED QUARTERLY FINANCIAL DATA


	December 31,				September 30,				June 30,				March 31,
	2020		2019		2020		2019		2020		2019		2020		2019
INCOME
Net premiums earned	$	108,146	$	185,336	$	161,724	$	175,802	$	142,871	$	190,962	$	159,351	$	251,947
Fees and commission income	14,121		9,522		10,787		6,437		10,010		6,017		7,528		6,477
Net investment income	61,530		76,847		72,130		81,502		94,443		74,271		74,714		75,651
Net realized and unrealized gains (losses)	803,467		153,477		500,005		145,060		967,608		260,669		(629,061)		452,760
Other income (losses)	33,372		21,703		48,404		822		(1,087)		8,831		20,443		5,714
	1,020,636		446,885		793,050		409,623		1,213,845		540,750		(367,025)		792,549
EXPENSES
Net incurred losses and loss adjustment expenses	76,248		48,068		109,686		163,258		186,692		146,554		43,300		256,299

Acquisition costs	38,202		78,417		37,708		33,310		49,067		51,081		46,043		77,801
General and administrative expenses	142,394		116,780		115,828		97,365		144,830		100,676		98,427		98,263
Interest expense	16,872		13,519		15,003		14,950		14,018		13,036		13,415		11,036
Net foreign exchange losses (gains)	15,018		12,186		8,156		(13,665)		5,158		(2,579)		(11,939)		(3,854)

	288,734		268,970		286,381		295,218		399,765		308,768		189,246		439,545
EARNINGS (LOSS) BEFORE INCOME TAXES	731,902		177,915		506,669		114,405		814,080		231,982		(556,271)		353,004
Income tax benefit (expense)	1,468		12,893		(13,915)		(13,465)		(16,652)		(7,698)		5,272		(4,102)
Earnings (losses) from equity method investments	85,844		11,722		149,065		17,703		(8,790)		17,713		12,450		8,772
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	819,214		202,530		641,819		118,643		788,638		241,997		(538,549)		357,674
Net earnings (loss) from discontinued operations, net of income taxes	15,441		(4,666)		4,031		7,916		(1,152)		(3,943)		(2,069)		8,068
NET EARNINGS (LOSS)	834,655		197,864		645,850		126,559		787,486		238,054		(540,618)		365,742
Net (earnings) loss attributable to noncontrolling interest	(3,131)		4,900		(21,912)		109		19,992		2,713		32,722		2,148
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	831,524		202,764		623,938		126,668		807,478		240,767		(507,896)		367,890
Dividends on preferred shares	(8,925)		(8,925)		(8,925)		(8,925)		(8,925)		(8,925)		(8,925)		(9,139)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$	822,599	$	193,839	$	615,013	$	117,743	$	798,553	$	231,842	$	(516,821)	$	358,751

Earnings (loss) per ordinary share attributable to Enstar ordinary shareholders:
Basic:
Net earnings (loss) from continuing operations	$	37.91	$	9.15	$	28.39	$	5.26	$	37.06	$	10.90	$	(23.93)	$	16.49
Net earnings (loss) from discontinued operations	0.33		(0.13)		0.11		0.22		(0.03)		(0.11)		(0.05)		0.22
Basic	$	38.24	$	9.02	$	28.50	$	5.48	$	37.03	$	10.79	$	(23.98)	$	16.71
Diluted(1):
Net earnings (loss) from continuing operations	$	37.47	$	9.02	$	28.13	$	5.21	$	36.68	$	10.81	$	(23.93)	$	16.35
Net earnings (loss) from discontinued operations	0.32		(0.13)		0.11		0.21		(0.03)		(0.11)		(0.05)		0.22
Net earnings (loss) per ordinary share	$	37.79	$	8.89	$	28.24	$	5.42	$	36.65	$	10.70	$	(23.98)	$	16.57

(1) During a period of loss, the basic weighted average ordinary shares outstanding is used in the denominator of the diluted loss per ordinary share computation as the effect of including potentially dilutive securities would be anti-dilutive.

Schedule I - Summary of Investments Other Than Investments in Related Parties

12 Months Ended

Dec. 31, 2020

SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Abstract]

Schedule I - Summary of Investments Other Than Investments in Related Parties

SCHEDULE I

ENSTAR GROUP LIMITED

SUMMARY OF INVESTMENTS OTHER THAN INVESTMENTS IN RELATED PARTIES

As of December 31, 2020

(Expressed in thousands of U.S. Dollars)


Type of investment	Cost (1)		Fair Value		Amount at which shown in the balance sheet
Short-term and fixed maturity investments — Trading and short-term and fixed maturity investments within funds held - directly managed:(2)
U.S. government and agency	$	219,487	$	233,050	$	233,050
U.K. government	34,494		37,508		37,508
Other government	321,306		352,026		352,026
Corporate	3,353,054		3,749,383		3,749,383
Municipal	116,588		132,637		132,637
Residential mortgage-backed	219,360		225,074		225,074
Commercial mortgage-backed	554,639		577,602		577,602
Asset-backed	349,941		339,675		339,675
Total	5,168,869		5,646,955		5,646,955
Short-term and fixed maturity investments — AFS:(2)
U.S. government and agency	715,527		717,998		717,998
U.K. government	12,494		13,574		13,574
Other government	142,459		150,127		150,127
Corporate	1,873,184		1,937,349		1,937,349
Municipal	28,881		30,032		30,032
Residential mortgage-backed	326,268		328,871		328,871
Commercial mortgage-backed	273,516		276,488		276,488
Asset-backed	199,467		199,610		199,610
Total	3,571,796		3,654,049		3,654,049
Equities(3)	444,570		512,557		512,557
Other investments, at fair value(4)	982,770		982,770		982,770

Total	$	10,168,005	$	10,796,331	$	10,796,331

(1)Original cost of fixed maturity securities is reduced by repayments and adjusted for amortization of premiums or accretion of discounts.

(2)The difference in the amount of fixed maturities shown at fair value and the fixed maturities shown in our consolidated balance sheet relates to the fair value of $18.2 million as of December 31, 2020 for our investment in fixed maturities issued by affiliates of Stone Point. Refer to Note 21 - "Related Party Transactions" of the notes to the consolidated financial statements.

(3)The difference in the amount of equities shown at fair value and the equities shown in our consolidated balance sheet relates to the fair value of $77.1 million as of December 31, 2020 for our investment in a registered investment company affiliated with entities owned by Trident, $26.9 million as a co-investor alongside Stone Point and a $230.3 million investment in AmTrust. Refer to Note 21 - "Related Party Transactions" of the notes to the consolidated financial statements.

(4)The difference in the amount of other investments shown at fair value and the other investments shown in our consolidated balance sheet relates to the fair value of $3.3 billion as of December 31, 2020 for our other investments in funds or companies owned by or affiliated with certain related parties. Refer to Note 21 - "Related Party Transactions" of the notes to the consolidated financial statements.

Schedule II - Condensed Financial Statements

12 Months Ended

Dec. 31, 2020

Condensed Financial Information Disclosure [Abstract]

Schedule II - Condensed Financial Statements

SCHEDULE II

ENSTAR GROUP LIMITED

CONDENSED FINANCIAL INFORMATION OF REGISTRANT

Balance Sheets - Parent Company Only

As of December 31, 2020 and 2019


	2020		2019
	(in thousands of U.S. dollars, except share data)
ASSETS
Cash and cash equivalents	$	7,872	$	4,568
Balances due from subsidiaries	18,951		134,897
Investments in subsidiaries	7,887,255		6,050,197
Other assets	8,047		6,391
TOTAL ASSETS	$	7,922,125	$	6,196,053
LIABILITIES
Debt obligations	$	903,447	$	1,191,207
Balances due to subsidiaries	300,987		135,532
Other liabilities	43,296		27,131
TOTAL LIABILITIES	1,247,730		1,353,870
COMMITMENTS AND CONTINGENCIES
SHAREHOLDERS’ EQUITY










Ordinary shares (par value $1 each, issued and outstanding 2020: 22,085,232; 2019: 21,511,505):
Voting Ordinary Shares (issued and outstanding 2020: 18,575,550; 2019: 18,001,823)	18,576		18,002

Non-voting convertible ordinary Series C Shares (issued and outstanding 2020 and 2019: 2,599,672)	2,600		2,600
Non-voting convertible ordinary Series E Shares (issued and outstanding 2020 and 2019: 910,010)	910		910
Preferred Shares:
Series C Preferred Shares (issued and held in treasury 2020 and 2019: 388,571)	389		389
Series D Preferred Shares (issued and outstanding 2020 and 2019: 16,000)	400,000		400,000
Series E Preferred Shares (issued and outstanding 2020 and 2019: 4,400)	110,000		110,000
Treasury shares, at cost (Series C Preferred Shares 2020 and 2019: 388,571)	(421,559)		(421,559)
Joint Share Ownership Plan (voting ordinary shares, held in trust 2020: 565,630; 2019: 0)	(566)		—
Additional paid-in capital	1,836,074		1,836,778
Accumulated other comprehensive income	80,659		7,171
Retained earnings	4,647,312		2,887,892
Total Enstar Group Limited Shareholders’ Equity	6,674,395		4,842,183
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$	7,922,125	$	6,196,053

See accompanying notes to the Condensed Financial Information of Registrant

SCHEDULE II

ENSTAR GROUP LIMITED

CONDENSED FINANCIAL INFORMATION OF REGISTRANT - CONTINUED

Statements of Earnings - Parent Company Only

For the Years Ended December 31, 2020, 2019 and 2018


	2020		2019		2018
	(in thousands of U.S. dollars)
INCOME
Net investment income	$	1,680	$	3,649	$	142


	1,680		3,649		142
EXPENSES
General and administrative expenses	45,689		44,964		68,977
Interest expense	51,739		51,508		27,353
Net foreign exchange losses (gains)	(2,655)		(21,516)		7,655
	94,773		74,956		103,985
EARNINGS (LOSSES) BEFORE EQUITY IN UNDISTRIBUTED EARNINGS OF SUBSIDIARIES	(93,093)		(71,307)		(103,843)
Equity in undistributed earnings (losses) of subsidiaries - continuing operations	1,831,886		1,002,021		(47,867)
Equity in undistributed earnings (losses) of subsidiaries - discontinued operations	16,251		7,375		1,489
NET EARNINGS	1,755,044		938,089		(150,221)
Dividends on preferred shares	(35,700)		(35,914)		(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$	1,719,344	$	902,175	$	(162,354)

See accompanying notes to the Condensed Financial Information of Registrant

Statements of Comprehensive Income - Parent Company Only

For the Years Ended December 31, 2020, 2019 and 2018


	2020		2019		2018
	(in thousands of U.S. dollars)
NET EARNINGS	$	1,755,044	$	938,089	$	(150,221)
OTHER COMPREHENSIVE INCOME (LOSS) RELATING TO SUBSIDIARIES, NET OF TAX	73,488		(3,269)		(27)
COMPREHENSIVE INCOME	$	1,828,532	$	934,820	$	(150,248)

See accompanying notes to the Condensed Financial Information of Registrant

SCHEDULE II

ENSTAR GROUP LIMITED

CONDENSED FINANCIAL INFORMATION OF REGISTRANT - CONTINUED

Statements of Cash Flows - Parent Company Only

For the Years Ended December 31, 2020, 2019 and 2018


	2020		2019		2018
	(in thousands of U.S. dollars)
OPERATING ACTIVITIES:
Net cash flows provided by (used in) operating activities	$	117,220	$	(128,462)	$	(128,382)
INVESTING ACTIVITIES:
Dividends and return of capital from subsidiaries	44,000		65,500		101,000
Contributions to subsidiaries	(26,000)		(240,382)		(660,339)
Net cash flows provided by (used in) investing activities	18,000		(174,882)		(559,339)
FINANCING ACTIVITIES:
Net proceeds from the issuance of preferred shares	—		—		495,357
Dividends on preferred shares	(35,700)		(35,914)		(12,133)
Repurchase of shares	(26,006)		—		—
Repayment of loans	(449,210)		(219,000)		(898,633)
Receipt of loans	379,000		547,613		1,115,885
Net cash flows provided by (used in) financing activities	(131,916)		292,699		700,476
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	3,304		(10,645)		12,755
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	4,568		15,213		2,458
CASH AND CASH EQUIVALENTS, END OF YEAR	$	7,872	$	4,568	$	15,213

See accompanying notes to the Condensed Financial Information of Registrant

Notes to the Condensed Financial Information of Registrant

The Condensed Financial Information of Registrant should be read in conjunction with our consolidated financial statements and the accompanying notes thereto included in Part II - Item 8 of this Annual Report on Form 10-K. Our wholly-owned and majority owned subsidiaries are recorded based upon our proportionate share of our subsidiaries' net assets (similar to presenting them on the equity method).

Net investment income relates to interest on loans to subsidiaries. For the years ended December 31, 2020, 2019, and 2018, interest paid was $46.5 million, $46.5 million, and $25.1 million, respectively.

Investing activities in the Condensed Statements of Cash Flows primarily represents the flow of funds to and from subsidiaries to provide cash on hand to fund business acquisitions and significant new business.

Non-Cash investing activities during the years ended December 31, 2020, 2019, and 2018, included:

i.$130.0 million, $0 and $0, respectively, for dividends and return of capital from subsidiaries. In 2020, these transactions were to settle intercompany balances, resulting in a net reduction in balances due to subsidiaries and a decrease in investments in subsidiaries.

ii.$0, $0 and $414.8 million, respectively, for contributions to subsidiaries. In 2018, these transactions represented the contribution of the acquired outstanding shares and warrants of KaylaRe Holdings, Ltd, to another subsidiary company.

As of December 31, 2020 and 2019, parental guarantees and capital support instruments supporting subsidiaries' insurance obligations were $1.5 billion and $1.0 billion, respectively. In addition, as of December 31, 2020 and 2019, there were $210.0 million and $252.0 million, respectively, of unsecured letters of credit for Funds at Lloyd's which have a parental guarantee. Furthermore, as of December 31, 2020, we also guarantee the Junior Subordinated Notes issued in 2020 for an aggregate principal amount of $350.0 million.

As of December 31, 2020 and 2019, retained earnings were $4,647.3 million and $2,887.9 million, respectively, an increase of $1,759.4 million. This increase was primarily attributable to the net earnings of $1,719.3 million.

Schedule III - Supplementary Insurance Information

12 Months Ended

Dec. 31, 2020

SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Abstract]

Schedule III - Supplementary Insurance Information

SCHEDULE III

ENSTAR GROUP LIMITED

SUPPLEMENTARY INSURANCE INFORMATION

(Expressed in thousands of U.S. Dollars)


	As of December 31,								Year ended December 31,
	Deferred Acquisition Costs		Reserves for Losses and Loss Adjustment Expenses		Unearned Premiums		Policy Benefits for Life and Annuity Contracts		Net Premiums Earned		Net Investment Income		Losses and Loss Expenses and Policy Benefits		Amortization of Deferred Acquisition Costs		Other Operating Expenses		Net Premiums Written
2020
Non-life Run-off (1)	$	22,736	$	9,235,082	$	71,629	$	—	$	58,695	$	282,048	$	44,995	$	20,177	$	298,717	$	2,987
Atrium (1)	—		—		—		—		175,393		5,542		87,226		59,611		34,600		183,194
StarStone	21,439		1,327,956		191,502		—		318,115		27,443		266,738		90,797		123,864		233,202
Other	264		30,244		11,550		—		19,889		(12,216)		16,967		435		44,298		13,441
Total	$	44,439	$	10,593,282	$	274,681	$	—	$	572,092	$	302,817	$	415,926	$	171,020	$	501,479	$	432,824
2019
Non-life Run-off	$	41,753	$	8,295,361	$	129,715	$	—	$	168,496	$	275,236	$	51,625	$	73,642	$	270,445	$	(25,338)
Atrium	22,184		231,672		80,863		—		164,059		7,049		77,276		56,956		28,277		172,356
StarStone	52,188		1,318,294		305,116		—		451,112		34,396		469,240		109,369		68,417		379,523
Other	388		23,077		17,998		—		20,380		(8,410)		16,038		642		45,945		18,512
Total	$	116,513	$	9,868,404	$	533,692	$	—	$	804,047	$	308,271	$	614,179	$	240,609	$	413,084	$	545,053
2018
Non-life Run-off	$	4,378	$	7,540,662	$	136,023	$	—	$	9,427	$	226,287	$	(306,067)	$	4,006	$	197,824	$	(9,217)
Atrium	20,355		241,284		70,429		—		146,315		5,686		69,810		50,646		24,698		153,488
StarStone	62,161		1,247,989		382,605		—		515,163		27,000		543,080		120,517		98,137		478,009
Other	364		18,861		17,002		105,080		24,874		2,725		16,899		2,686		28,127		32,067
Total	$	87,258	$	9,048,796	$	606,059	$	105,080	$	695,779	$	261,698	$	323,722	$	177,855	$	348,786	$	654,347

(1) As of December 31, 2020, the assets and liabilities of Northshore, the holding company which owns Atrium and Arden (a Non-life Run-off subsidiary), were classified as held-for-sale. Deferred acquisition costs, reserves for losses and loss adjustment expenses and unearned premiums for Northshore were $24.0 million, $254.1 million and $91.4 million, respectively. Refer to Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations" for further information.

Schedule IV - Reinsurance

12 Months Ended

Dec. 31, 2020

SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract]

Schedule IV - Reinsurance

SCHEDULE IV

ENSTAR GROUP LIMITED

REINSURANCE

For the Years Ended December 31, 2020, 2019 and 2018

(Expressed in thousands of U.S. Dollars)


	Gross		Ceded to Other Companies		Assumed from Other Companies		Net Amount		Percentage of Amount Assumed to Net

2020

Premiums earned:
Property and casualty	$	542,119	$	(157,826)	$	187,799	$	572,092	32.8	%

Total premiums earned	$	542,119	$	(157,826)	$	187,799	$	572,092

2019
Life insurance in force	$	725,293	$	(65,795)	$	—	$	659,498	—	%
Premiums earned:
Property and casualty	679,212		(145,460)		269,023		802,775		33.5	%
Life and annuities	1,295		(23)		—		1,272		—	%
Total premiums earned	$	680,507	$	(145,483)	$	269,023	$	804,047

2018
Life insurance in force	$	855,366	$	(84,603)	$	—	$	770,763	—	%
Premiums earned:
Property and casualty	539,169		(166,308)		319,052		691,913		46.1	%
Life and annuities	3,892		(26)		—		3,866		—	%
Total premiums earned	$	543,061	$	(166,334)	$	319,052	$	695,779

Schedule V - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2020

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Schedule V - Valuation and Qualifying Accounts

SCHEDULE V

ENSTAR GROUP LIMITED

VALUATION AND QUALIFYING ACCOUNTS

For the Years Ended December 31, 2020, 2019 and 2018

(Expressed in thousands of U.S. Dollars)


	Balance at Beginning of Year		Charged to costs and expenses		Charged to other accounts (1)		Deductions (2)		Balance at End of Year
December 31, 2020
Reinsurance balances recoverable on paid and unpaid losses:
Allowance for estimated uncollectible reinsurance	$	147,639	$	—	$	124	$	(10,641)	$	137,122
Insurance balances recoverable:
Allowance for estimated uncollectible insurance	3,818		—		1,006		—		4,824
Valuation allowance for deferred tax assets	117,390		3,854		—		(3,015)		118,229

December 31, 2019
Reinsurance balances recoverable on paid and unpaid losses:
Allowance for estimated uncollectible reinsurance	156,732		—		111		(9,204)		147,639
Insurance balances recoverable:
Allowance for estimated uncollectible insurance	—		—		3,818		—		3,818
Valuation allowance for deferred tax assets	212,113		2,792		—		(97,515)		117,390

December 31, 2018
Reinsurance balances recoverable on paid and unpaid losses:
Allowance for estimated uncollectible reinsurance	165,213		—		(1,837)		(6,644)		156,732
Valuation allowance for deferred tax assets	188,300		(2,492)		18,000		8,305		212,113

(1)The 2020 amount includes $3.0 million for the cumulative effect of change in accounting principle.

(2)Credited to the related asset account.

Schedule VI - Supplementary Information Concerning Property/Casualty Insurance Operations

12 Months Ended

Dec. 31, 2020

SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Abstract]

Schedule VI - Supplementary Information Concerning Property/Casualty Insurance Operations

SCHEDULE VI

ENSTAR GROUP LIMITED

SUPPLEMENTARY INFORMATION CONCERNING PROPERTY/CASUALTY INSURANCE OPERATIONS

As of and for the years ended December 31, 2020, 2019 and 2018

(Expressed in thousands of U.S. Dollars)


	As of December 31,						Year ended December 31,
Affiliation with Registrant	Deferred Acquisition Costs		Reserves for Unpaid Losses and Loss Adjustment Expenses		Unearned Premiums		Net Premiums Earned		Net Investment Income		Net Losses and Loss Expenses Incurred				Net Paid Losses and Loss Expenses		Amortization of Deferred Acquisition Costs		Net Premiums Written
											Current Year		Prior Year
Consolidated Subsidiaries
2020	$	44,439	$	10,593,282	$	274,681	$	572,092	$	302,817	$	405,178	$	10,748	$	(1,485,489)	$	171,020	$	432,824
2019	116,513		9,868,404		533,692		802,775		307,775		580,074		34,105		(1,788,470)		240,432		543,781
2018	87,258		9,048,796		606,059		691,912		260,120		533,081		(209,359)		(1,334,786)		177,855		650,484

Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Preparation	The consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("U.S. GAAP").
Basis of Consolidation	The consolidated financial statements include our assets, liabilities and results of operations as of December 31, 2020 and 2019 and for the years ended December 31, 2020, 2019 and 2018. Results of operations for acquired subsidiaries are included from the date of acquisition. All significant intercompany transactions and balances have been eliminated.
Use of Estimates	The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amount of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Our actual results may differ materially from these estimates. The impact of changes in estimates are reflected in earnings in the period during which the estimate is changed. Accounting policies that we believe are most dependent on assumptions and estimates are considered to be our critical accounting estimates and are related to the determination of: •liability for losses and loss adjustment expenses ("LAE"); •reinsurance balances recoverable on paid and unpaid losses; •defendant asbestos and environmental liabilities and related insurance balances recoverable; •valuation allowances on reinsurance balances recoverable and deferred tax assets; •impairment charges, including credit allowances on investment securities classified as available-for-sale ("AFS"), and impairments on deferred charge assets; •gross and net premiums written and net premiums earned; •fair value measurements of investments; •fair value estimates associated with accounting for acquisitions; •fair value estimates associated with loss portfolio transfer reinsurance agreements for which we have elected the fair value option; and •redeemable noncontrolling interests.
Premiums	Non-Life Non-life premiums written are earned on a pro-rata basis over the period the coverage is provided. Reinsurance premiums are recorded at the inception of the policy, are based upon contractual terms and, for certain business, are estimated based on underlying contracts or from information provided by insureds and/or brokers. Changes in reinsurance premium estimates are expected and may result in adjustments in future periods. Any subsequent differences arising on such estimates are recorded as premiums written in the period in which they are determined. Certain non-life contracts are retrospectively rated and provide for a final adjustment to the premium based on the final settlement of all losses. Premiums on such contracts are adjusted based upon contractual terms, and management judgment is involved with respect to the estimate of the amount of losses that we expect to incur. Additional premiums are recognized at the time loss thresholds specified in the contract are exceeded and are earned over the coverage period, or are earned immediately if the period of risk coverage has passed. Unearned Premium Reserves and Premiums Receivable Unearned premium reserves represent the unexpired portion of policy premiums. For retrospectively rated contracts as well as those contracts whose written premium amounts are recorded based on premium estimates at inception, changes to accrued premiums arising from changes to these estimates are reflected as changes in premium balances receivable where appropriate. Premium balances receivable are reported net of an allowance for expected credit losses as appropriate. The allowance is based upon our ongoing review of amounts outstanding, historical loss data, including delinquencies and write-offs, current and forecasted economic conditions and other relevant factors. However, the credit risk on our premiums receivable balances is substantially reduced where we have the ability to cancel the underlying policy if the policyholder does not pay the related premium.
Acquisition Costs	Acquisition costs, consisting principally of commissions and brokerage expenses and certain premium taxes and fees incurred at the time a contract or policy is issued and that vary with and are directly related to the successful efforts of acquiring new insurance contracts or renewing existing insurance contracts, are deferred and amortized over the period in which the related premiums are earned. Deferred acquisition costs are limited to their estimated realizable value by line of business based on the related unearned premiums, anticipated claims and claim expenses and anticipated investment income. A premium deficiency occurs if the sum of anticipated losses and loss adjustment expenses exceed unearned premiums, deferred acquisition costs and anticipated investment income. A premium deficiency is initially recognized by charging any deferred acquisition costs to expense to the extent required in order to eliminate the deficiency. If the premium deficiency exceeds the deferred acquisition costs then a liability is accrued for the excess deficiency.
Losses and LAE	Non-life Run-off The liability for losses and LAE in the Non-life Run-off segment includes an amount determined from reported claims and an amount, based on historical loss experience and industry statistics, for losses incurred but not reported ("IBNR") determined using a variety of actuarial methods. These estimates are continually reviewed and are necessarily subject to the impact of future changes in factors such as claim severity and frequency, changes in economic conditions including the impact of inflation, legal and judicial developments, and medical cost trends. Our estimates, at inception and on an ongoing basis, do not include an estimate for potential future commutations and policy buybacks. Commutations and policy buybacks are often unique and circumstance-based, and each commutation or policy buyback is separately negotiated. Therefore, the successful execution of one commutation or policy buyback does not necessarily impact the likelihood of other commutations or policy buybacks occurring in the future. While we believe that our liability for losses and LAE is adequate, the ultimate amount may be in excess of, or less than, the amounts recorded on our financial statements. Adjustments will be reflected as part of the net increase or reduction in losses and LAE liabilities in the periods in which they become known. Premium and commission adjustments may be triggered by changes in incurred losses, and any changes in such amounts are recorded in the same period that the related change in incurred loss is recognized. Commutations of acquired companies’ exposures have the effect of accelerating the payout of claims compared to the probability-weighted ranges of actuarially projected cash flows that we applied when estimating the fair values of assets and liabilities at the time of acquisition. Commutations and policy buybacks provide an opportunity for us to exit exposures to certain policies and insureds generally at a discount to our estimate of the ultimate liability and provide us with the ability to eliminate exposure to further losses. Commutations and policy buybacks can be beneficial to us as they legally extinguish liabilities in full, reduce the potential for future adverse loss development, and reduce future claims handling costs. Any material acceleration of payout together with the impact of any material loss reserve savings in any period will also accelerate the amortization of fair value adjustments and deferred charge assets and gain liabilities in that period. Commutations are only executed directly with insureds or reinsureds and any gains realized or losses incurred on the settlement of losses and LAE liabilities through commutations or policy buybacks are recognized upon the execution of a commutation or policy buyback with the insured or reinsured. Our (re)insurance subsidiaries also establish provisions for LAE relating to run-off costs for the estimated duration of the run-off, which are included in the liability for losses and LAE. These provisions are assessed at each reporting date, and provisions relating to future periods are adjusted to reflect any changes in estimates of the periodic run-off costs or the duration of the run-off, including the impact of any acceleration of the run-off period that may be caused by commutations. Provisions relating to the current period together with any adjustment to future run-off provisions are included in net incurred losses and LAE in the consolidated statements of earnings. Atrium and StarStone The reserves for losses and LAE in the Atrium and StarStone segments include reserves for unpaid reported losses and for IBNR loss reserves. The reserves for unpaid reported losses and loss expenses are established by management based on reports from brokers, ceding companies and insureds and represent the estimated ultimate cost of events or conditions that have been reported to or specifically identified by us. The reserve for IBNR losses is established by us based on actuarially determined estimates of ultimate losses and loss expenses. Inherent in the estimate of ultimate losses and loss expenses are expected trends in claim severity and frequency and other factors which may vary significantly as claims are settled. Accordingly, ultimate losses and loss expenses may differ from the amounts recorded in the consolidated financial statements. These estimates are reviewed regularly and, as experience develops and new information becomes known, the reserves are adjusted as necessary. Such adjustments, if any, will be recorded in earnings in the period in which they become known. Prior period development arises from changes to loss estimates recognized in the current year that relate to loss reserves established in previous calendar years. Components of Net Incurred Losses and LAE Included within the total net incurred losses and LAE on our consolidated statement of earnings are the following items: •Net losses paid: paid losses and LAE, net of related reinsurance recoveries. •Net change in case and LAE reserves: the change in case reserves and associated LAE, net of related reinsurance recoveries. •Net change in IBNR reserves: the change in IBNR reserves, net of related reinsurance recoveries. •Increase (reduction) in estimates of net ultimate losses: the total of net losses paid, net change in case and LAE reserves and the net change in IBNR. This includes the net impact of commutations and policy buybacks on the liability for losses and LAE reserves and reinsurance recoveries. •Increase (reduction) in provisions for unallocated LAE: the net change in our provision for unallocated LAE. •Amortization of deferred charge assets and deferred gain liabilities: relates to retroactive reinsurance contracts where, if at the inception of the contract, the estimated undiscounted ultimate losses payable are in excess of the premiums received, a deferred charge asset is recorded for the excess; whereas, if the premiums received are in excess of the estimated undiscounted ultimate losses payable, a deferred gain liability is recorded for the excess, such that we don't record any gain or loss at the inception of these retroactive reinsurance contracts. In addition, for retrocessions of losses and LAE reserves that we have assumed through retroactive reinsurance contracts where the retroceded liabilities exceed the retrocession premiums paid, we record the excess as a deferred gain liability which is amortized to earnings over the estimated period during which the losses paid on the assumed retroceded liabilities are recovered from the retrocessionaire. •Amortization of fair value adjustments: the amortization of the fair value adjustments associated with acquired companies, where the assumed losses and LAE reserves and the acquired reinsurance recoveries are fair valued on acquisition. •Changes in fair value - fair value option: the changes in the fair value for reinsurance agreements where we have elected the fair value option. The change in fair value component includes the changes in the discounted cash flows and risk margin. The underlying ("nominal") net losses paid, net change in case and LAE reserves and the net change in IBNR reserves relating to these reinsurance agreements for which we have elected the fair value option are included within the appropriate line items described above. •Net incurred losses and LAE: the total of the increase (reduction) in estimates of net ultimate losses, increase (reduction) in provisions for unallocated LAE, amortization of deferred charge assets and deferred gain liabilities, amortization of fair value adjustments and changes in fair value - fair value option.
Defendant Asbestos and Environmental Liabilities	We acquired DCo LLC ("DCo") on December 30, 2016, and Morse TEC LLC ("Morse TEC") on October 30, 2019, as described in Note 3 - "Business Acquisitions." DCo and Morse TEC hold liabilities associated with personal injury asbestos claims and environmental claims arising from their legacy manufacturing operations. DCo and Morse TEC continue to process asbestos personal injury claims.Defendant asbestos and environmental liabilities on our consolidated balance sheets include amounts for indemnity and defense costs for pending and future claims, determined using standard actuarial techniques for asbestos-related exposures. Defendant asbestos and environmental liabilities also include amounts for environmental liabilities associated with DCo's and Morse TEC's properties.
Reinsurance Balances Recoverable on Paid and Unpaid Losses, Funds Held, and Retroactive Reinsurance	Amounts recoverable from reinsurers are estimated in a manner consistent with the underlying liability for losses and loss adjustment expenses. We report our reinsurance balances recoverable on paid and unpaid losses net of an allowance for estimated uncollectible amounts. The allowance is based upon our ongoing review of the outstanding balances and reflects factors such as the duration of the collection period, credit quality, changes in reinsurer credit standing, default rates specific to the individual reinsurer, the geographical location of the reinsurer, contractual disputes with reinsurers over individual contentious claims, contract language or coverage issues, industry analyst reports and consensus economic forecasts. A probability-of-default methodology that reflects current and forecasted economic conditions is used to estimate the allowance for uncollectible reinsurance due to credit-related factors. See "New Accounting Standards Adopted in 2020" below for the discussion on our adoption of the credit losses standard. The allowance also includes estimated uncollectible amounts related to dispute risk with reinsurers. Amounts deemed to be uncollectible, including amounts due from known insolvent reinsurers, are written off against the allowance. Changes in the allowance, as well as any subsequent collections of amounts previously written off, are reported as part of the net incurred losses and loss adjustment expenses in our consolidated statements of earnings. On an ongoing basis, we also evaluate and monitor the financial condition of our reinsurers under voluntary schemes of arrangement to minimize our exposure to significant losses from potential insolvencies. Under funds held arrangements, the reinsured company has retained funds that would otherwise have been remitted to our reinsurance subsidiaries. The funds balance is credited with investment income and losses payable are deducted. Funds held are shown under two categories on the consolidated balance sheets, funds held where we receive the underlying portfolio economics are shown as "Funds held - directly managed", and funds held where we receive a fixed crediting rate are shown as "Funds held by reinsured companies". Funds held by reinsured companies are carried at cost. Funds held - directly managed, are carried at fair value and represents the aggregate of funds held at cost and the value of an embedded derivative. The embedded derivative relates to our contractual right to receive the return on the underlying investment portfolio economics. The investment returns on both categories of funds held are recognized in net investment income and net realized and unrealized gains (losses). The revaluation of the embedded derivative is included in net unrealized gains (losses). Retroactive reinsurance policies provide indemnification for losses and LAE with respect to past loss events. In our Non-life Run-off segment we generally use the balance sheet accounting approach for assumed loss portfolio transfers, whereby at the inception of the contract there are no premiums or losses recorded in earnings. Deferred Charge Assets and Deferred Gain Liabilities If, at the inception of a Non-life Run-off retroactive reinsurance contract, the estimated undiscounted ultimate losses payable are in excess of the premiums received, a deferred charge asset is recorded for the excess; whereas, if the premiums received are in excess of the estimated undiscounted ultimate losses payable, a deferred gain liability is recorded for the excess, such that we don't record any gain or loss at the inception of these retroactive reinsurance contracts. In addition, for retrocessions of losses and LAE reserves that we have assumed through retroactive reinsurance contracts where the retroceded liabilities exceed the retrocession premiums paid, we record the excess as a deferred gain liability which is amortized to earnings over the estimated period during which the losses paid on the assumed retroceded liabilities are recovered from the retrocessionaire. The premium consideration that we charge the ceding companies under retroactive reinsurance contracts may be lower than the undiscounted estimated ultimate losses payable due to the time value of money. After receiving the premium consideration in full from our cedents at the inception of the contract, we invest the premium received over an extended period of time, thereby generating investment income. We expect to generate profits from these retroactive reinsurance contracts when taking into account the premium received and expected investment income, less contractual obligations and expenses. Deferred charge assets, recorded in other assets, and deferred gain liabilities, recorded in other liabilities, are amortized over the estimated claim payment period of the related contract with the periodic amortization reflected in earnings as a component of losses and LAE. The amortization of deferred charge assets and deferred gain liabilities is adjusted at each reporting period to reflect new estimates of the amount and timing of remaining loss and LAE payments. Changes in the estimated amount and the timing of payments of unpaid losses may have an effect on the unamortized deferred charge assets and deferred gain liabilities and the amount of periodic amortization. When liabilities for losses and LAE are extinguished through commutations and policy buybacks, they are removed from our estimates for the remaining loss and LAE payments, and this will generally result in an acceleration of the amortization of the deferred charge assets and deferred gain liabilities. Deferred charge assets are assessed at each reporting period for impairment and if the asset is determined to be impaired, then it is written down in the period in which the determination is made with that write down reflected in earnings as a component of net incurred losses and LAE. Fair Value Option In our Non-life Run-off segment, we have elected to apply the fair value option for certain loss portfolio transfer reinsurance transactions. This is an irrevocable election that applies to all balances under the insurance contract, including funds held assets, reinsurance balances recoverable on paid and unpaid losses, and the liability for losses and loss adjustment expenses. We use an internal model to calculate the fair value of the liability for losses and loss adjustment expenses and the reinsurance balances recoverable on paid and unpaid losses. The nominal amounts related to the funds held assets, reinsurance balances recoverable on paid and unpaid losses, and the liability for losses and loss adjustment expenses, are inputs in our internal model. Note 12 - "Fair Value Measurements" describes the internal model, including the observable and unobservable inputs used in the model.
Insurance Balances Recoverable	Amounts billed to and due from insurers providing coverage for our defendant asbestos liabilities are calculated in accordance with the terms of the individual insurance contracts. The insurance balances recoverable related to our defendant asbestos liabilities are presented net of a provision for uncollectible amounts, reflecting the amount deemed not collectible primarily due to credit quality and contractual disputes with insurers over coverage issues.
Investments	Short-term investments and fixed maturity investments Short-term investments comprise investments with a maturity greater than three months up to one year from the date of purchase. Fixed maturities comprise investments with a maturity of greater than one year from the date of purchase. Short-term and fixed maturity investments classified as trading are carried at fair value, with realized and unrealized gains and losses included in net earnings and reported as net realized and unrealized gains and losses. Short-term and fixed maturity investments classified as AFS are carried at fair value, with unrealized gains and losses excluded from net earnings and reported as a separate component of accumulated other comprehensive income (loss) ("AOCI"). Realized gains and losses on sales of investments classified as AFS are recognized in the consolidated statements of earnings. The costs of short-term and fixed maturity investments are adjusted for amortization of premiums and accretion of discounts, recognized using the effective yield method and included in net investment income. For mortgage-backed and asset-backed investments, and any other holdings for which there is a prepayment risk, prepayment assumptions are evaluated and reviewed on a regular basis. Investment purchases and sales are recorded on a trade-date basis. Realized gains and losses on the sale of investments are based upon specific identification of the cost of investments. Allowance for Credit Losses We perform a detailed analysis every reporting period to identify any credit losses on our investment portfolios not measured at fair value through net earnings. Some of the factors that we consider when assessing whether an allowance for credit losses is required on our debt securities include: (1) the extent to which the fair value has been less than the amortized cost; (2) the financial condition, near-term and long-term prospects of the issuer, including the relevant industry conditions and trends, and implications of rating agency actions and offering prices; (3) the likelihood of the recoverability of principal and interest; and (4) whether it is more likely than not that we will be required to sell the security prior to an anticipated recovery in value. With effect from January 1, 2020, credit losses on our AFS debt securities are recognized through an allowance account which is deducted from the amortized cost basis of the security, with the net carrying value of the security presented on the consolidated balance sheet at the amount expected to be collected. To calculate the amount of the credit loss, we compare the present value of the expected future cash flows with the amortized cost basis of the AFS debt security, with the amount of the credit loss recognized being limited to the excess of the amortized cost basis over the fair value of the AFS debt security, effectively creating a “fair value floor”. See "New Accounting Standards Adopted in 2020" below for the discussion on our adoption of the credit losses standard. For our AFS debt securities that we do not intend to sell or for which it is more likely than not that we will not be required to sell before an anticipated recovery in value, we separate the credit loss component of any unrealized losses from the amount related to all other factors and report the credit loss component in net realized investment gains (losses) in our consolidated statements of earnings. The unrealized losses related to non-credit factors is reported in other comprehensive income. The allowance for credit losses account is adjusted for any additional credit losses, write-offs and subsequent recoveries and is reflected in earnings. For our AFS debt securities where we record a credit loss, a determination is made as to the cause of the credit loss and whether we expect a recovery in the fair value of the security. For our AFS debt securities where we expect a recovery in fair value, the constant effective yield method is utilized, and the investment is amortized to par. For our AFS debt securities that we intend to sell or for which it is more likely than not that we will be required to sell before an anticipated recovery in fair value, the full amount of the unrealized loss is included in net realized investment gains (losses). The new cost basis of the investment is the previous amortized cost basis less the credit loss recognized in net realized investment gains (losses). The new cost basis is not adjusted for any subsequent recoveries in fair value. We report the investment income accrued on our AFS debt securities within other assets and therefore separately from the underlying AFS debt securities. In addition, due to the short-term period during which accrued investment income remains unpaid, which is typically six months or less, since the coupon on our AFS debt securities is paid semi-annually or more frequently, we have elected not to establish an allowance for credit losses on our accrued investment income balances. Accrued investment income is written off through net realized investment gains (losses) at the time the issuer of the debt security defaults or is expected to default on payments. Uncollectible debt securities are written off when we determine that no additional payments of principal or interest will be received. Other-Than-Temporary Impairments ("OTTI") As discussed above and below, with effect from January 1, 2020, we adopted the new credit losses standard which replaced the OTTI model that was previously applicable to our AFS debt securities. The new approach now requires the recognition of impairment charges relating to credit losses through an allowance account and limits the amount of credit loss to the difference between a security’s amortized cost basis and its fair value. A description of our historical OTTI process which was in place prior to our adoption of the new credit losses standard and which applied to our comparative financial statements is provided below. Fixed maturity investments classified as AFS were reviewed quarterly to determine if they had sustained an impairment of value that was, based on our judgment, considered to be other than temporary. The process included reviewing each fixed maturity investment whose fair value was below amortized cost and: (1) determining if we had the intent to sell the fixed maturity investment; (2) determining if it was more likely than not that we would be required to sell the fixed maturity investment before its anticipated recovery; and (3) assessing whether a credit loss existed, that is, whether we anticipated if the present value of the cash flows expected to be collected from the fixed maturity investment would be less than the amortized cost basis of the investment. In assessing whether it was more likely than not that we would be required to sell a fixed maturity investment before its anticipated recovery, we considered various factors including our future cash flow requirements, legal and regulatory requirements, the level of our cash, cash equivalents, short-term investments and fixed maturity investments available-for-sale in an unrealized gain position, and other relevant factors. In evaluating credit losses, we considered a variety of factors in the assessment of a fixed maturity investment including: (1) the time period during which there had been a significant decline below cost; (2) the extent of the decline below cost and par; (3) the potential for the investment to recover in value; (4) an analysis of the financial condition of the issuer; (5) the rating of the issuer; and (6) failure of the issuer of the investment to make scheduled interest or principal payments. If we concluded that an investment was other-than-temporarily impaired, then the difference between the fair value and the amortized cost of the investment was presented as an OTTI charge in the consolidated statements of earnings, with an offset for any non-credit related loss component of the OTTI charge recognized in other comprehensive income. Accordingly, only the credit loss component of the OTTI amount would have an impact on our earnings. Equities We hold investments in publicly traded equities and exchange-traded funds as well as in privately held equities. Our equity investments are carried at fair value with realized and unrealized gains and losses included in net earnings and reported as net realized and unrealized gains and losses. Other investments, at fair value Other investments include investments in limited partnerships and limited liability companies (collectively "private equities") and fixed income funds, hedge funds, equity funds, private credit funds and collateralized loan obligation ("CLO") equity funds that carry their investments at fair value, as well as direct investments in CLO equities. These other investments are stated at fair value, which ordinarily will be the most recently reported net asset value as advised by the fund manager or administrator. Many of our fund investments publish net asset values on a daily basis and provide daily liquidity while others report on a monthly or quarterly basis. The change in fair value is included in net realized and unrealized gains and losses on investments and recognized in net earnings. Equity method investments Investments in which the Company has significant influence over the operating and financial policies of the investee are classified as equity method investments and are accounted for using the equity method of accounting. In applying the equity method of accounting, investments are initially recorded at cost and are subsequently adjusted based on the Company's proportionate share of net income or loss of the investee, net of any distributions received from the investee. We typically record our proportionate share of an investee's net income or loss on a quarter lag in line with the timing of when they report their financial information to us. Any adjustments made to the carrying value of our equity method investees are based on the most recently available financial information from the investees. Changes in the carrying value of such investments are recorded in our consolidated statements of earnings as earnings (losses) from equity method investments. Any decline in the value of our equity method investments considered by management to be other-than-temporary is reflected in our consolidated statements of earnings in the period in which it is determined.
Cash and cash equivalents	Cash equivalents includes money market funds, fixed interest deposits and all highly liquid debt instruments purchased with an original maturity of three months or less.
Variable Interest Entities	We have investments in certain limited partnership funds which are deemed to be variable interest entities (“VIEs”) and which are included in other investments at the reported net asset value (“NAV”). Determining whether to consolidate a VIE may require judgment in assessing (i) whether an entity is a VIE, and (ii) if we are the entity’s primary beneficiary and thus required to consolidate the entity. To determine if we are the primary beneficiary of a VIE, we evaluate whether we have (i) the power to direct the activities that most significantly impact the VIE’s economic performance, and (ii) the obligation to absorb losses or the right to receive benefits of the VIE that could potentially be significant to the VIE. Our evaluation includes identification of the activities that most significantly impact the VIE’s economic performance and an assessment of our ability to direct those activities based on governance provisions, contractual arrangements to provide or receive certain services, funding commitments and other applicable agreements and circumstances. Our assessment of whether we are the primary beneficiary of our VIEs requires significant assumptions and judgment.
Fees and Commission Income	Fees and commission income primarily includes profit commissions earned from managed Lloyd's syndicates as well as fees earned under fronting and consulting arrangements with third-party clients, which are recorded on an accrual basis.
Foreign Exchange	Our reporting currency is the U.S. dollar. Assets and liabilities of certain of our subsidiaries and equity method investees whose functional currency is not the U.S. dollar are translated at period end exchange rates. Revenues and expenses of such foreign entities are translated at average exchange rates during the year. The effect of the currency translation adjustments for these foreign entities is included in accumulated other comprehensive income (loss). Other foreign currency assets and liabilities that are considered monetary items are translated at exchange rates in effect at the balance sheet date. Foreign currency revenues and expenses are translated either at transaction date exchange rates or using an appropriately weighted average exchange rate for the reporting period. These exchange gains and losses are recognized in net earnings.
Share-based Compensation	We primarily use four types of share-based compensation arrangements: (i) restricted shares, restricted share units and performance share units ("PSUs"), (ii) joint share ownership program ("JSOP"), (iii) cash-settled stock appreciation rights ("SARs") and (iv) shares issued under our employee share purchase plans. With the exception of SARs and the incentive plan awards issued to certain employees of Atrium and StarStone, our share-based compensation awards qualify for equity classification. For equity-classified awards, the fair value of the compensation cost is measured at the grant date and is expensed over the service period of the award within general and administrative expenses in the consolidated statements of earnings except for PSUs where the expense also varies depending on the performance multiplier on the award. The SARs, the Atrium and StarStone incentive plan awards are classified as liability awards. Liability classified awards are recorded at fair value within other liabilities in the consolidated balance sheet with changes in fair value relating to the vested portion of the award recorded within general and administrative expenses in the consolidated statements of earnings.
Derivative Instruments	We utilize derivative instruments in our foreign currency, investments and interest rate risk management strategies and recognize all derivatives as either assets or liabilities in the consolidated balance sheets and carry them at the fair value of the specific instrument utilized. Changes in the fair value as well as realized gains or losses on derivative instruments are recognized in net earnings if they are not designated as qualifying hedging instruments or if the criteria for establishing a perfectly effective designated hedging relationship for our net investment hedges has not been met. However, if a designated net investment hedge is deemed to be perfectly effective, then we recognize the changes in the fair value of the underlying hedging instrument in accumulated other comprehensive income (loss) until the application of hedge accounting is discontinued. Any cumulative gains or losses arising on designated net investment hedges are deferred in accumulated other comprehensive income (loss) until the cumulative translation adjustment ("CTA") from the underlying hedged net investment is recognized in net earnings due to a disposal, deconsolidation or substantial liquidation. Certain of our funds held arrangements also contain embedded derivatives as described above, which are carried at fair value. In addition, we may also hold equity call options and other derivatives carried at fair value, as part of our investment strategy.
Income Taxes	Certain of our subsidiaries and branches operate in jurisdictions where they are subject to taxation. Current and deferred tax expense or benefit is allocated to net earnings (loss), or, in certain cases, to discontinued operations or other comprehensive income (loss). Current tax is recognized and measured upon enacted tax laws and rates applicable in the relevant jurisdiction in the period in which the income tax becomes accruable or realizable. Deferred taxes are provided for temporary differences between the carrying amount of assets and liabilities used in the financial statements and the tax basis used in the various jurisdictional tax returns. When our assessment indicates that all or some portion of deferred tax assets will not be realized, a valuation allowance is recorded against the deferred tax assets to reduce the assets to an amount more likely than not to be realized. We recognize the benefit relating to tax positions only where the position is more likely than not to be sustained assuming examination by tax authorities. A recognized tax benefit is measured as the largest amount that is greater than 50 percent likely of being realized upon settlement. A liability or other adjustment is recognized for any tax benefit (along with any interest and penalty, if applicable) claimed in a tax return in excess of the amount allowed to be recognized in the financial statements under U.S. GAAP. Any changes in amounts recognized are recorded in the period in which they are determined in our consolidated statements of earnings.
Earnings Per Share	Basic earnings per share is based on the weighted average number of ordinary shares outstanding and excludes potentially dilutive securities such as restricted shares, restricted share units, warrants, options and convertible securities. Diluted earnings per share is based on the weighted average number of ordinary and ordinary share equivalents outstanding calculated using the treasury stock method for all potentially dilutive securities. When the effect of dilutive securities would be anti-dilutive, these securities are excluded from the calculation of diluted earnings per share.
Acquisitions	The acquisition method is used to account for all business acquisitions. This method requires that we record the acquired assets and liabilities at their estimated fair value. The fair values of each of the acquired reinsurance assets and liabilities are derived from probability-weighted ranges of the associated projected cash flows, based on actuarially prepared information and management’s run-off strategy. Our run-off strategy, as well as that of other run-off market participants, is expected to be different from the seller's as generally sellers are not specialized in running off (re)insurance liabilities whereas we and other market participants do specialize in such run-offs. The key assumptions used by us and, we believe, by other run-off market participants in the valuation of acquired companies are (i) the projected payout, timing and amount of claims liabilities; (ii) the related projected timing and amount of reinsurance collections; (iii) an appropriate discount rate, which is applied to determine the present value of the future cash flows; (iv) the estimated unallocated LAE to be incurred over the life of the run-off; (v) the impact of any accelerated run-off strategy; and (vi) an appropriate risk margin.
Acquisitions, Fair Value Adjustment	The difference between the nominal carrying values of the acquired reinsurance liabilities and assets as of the acquisition date and their fair value is recorded as a fair value adjustment ("FVA") on the consolidated balance sheet. The FVA is amortized over the estimated payout period of the acquired outstanding losses and LAE and reinsurance balances recoverable. To the extent the actual payout experience after the acquisition is materially faster or slower than anticipated at the time of the acquisition as a result of, (i) our active claims management strategies, which include commutations and policy buybacks, (ii) an adjustment to the estimated ultimate loss reserves, (iii) changes in bad debt provisions, or (iv) changes in estimates of future run-off costs following accelerated payouts, then the amortization of the FVA is adjusted to reflect such changes.
Intangible Assets	Intangible assets arising from our business acquisitions are classified as either definite-lived or indefinite-lived intangible assets. Definite-lived intangible assets are amortized over their useful lives with the amortization expense being recognized in the consolidated statements of earnings. Indefinite-lived intangible assets are however not subject to amortization. The carrying values of intangible assets are reviewed for indicators of impairment at least annually. Impairment is recognized if the carrying values of the definite-lived intangible assets are not recoverable from their undiscounted cash flows and is measured as the amount by which the carrying value exceeds the fair value. Similarly, for indefinite-lived intangible assets, if the carrying value of the asset exceeds its fair value, then an impairment loss is recognized in an amount equal to the excess.
Goodwill	The difference between the fair value of net assets acquired and the purchase price is recorded as goodwill and included as an asset on the consolidated balance sheet or as a gain from bargain purchase in the consolidated statements of earnings. Goodwill is established initially upon acquisition and assessed at least annually for impairment. If the goodwill asset is determined to be impaired it is written down in the period in which the determination is made.
Redeemable Noncontrolling Interest	In connection with the acquisitions of Arden, Atrium and StarStone, certain subsidiaries issued shares to noncontrolling interests. These shares provide certain redemption rights to the holders, which may be settled in our own shares or cash or a combination of cash and shares, at our option. Redeemable noncontrolling interests with redemption features that are not solely within our control are classified within temporary equity in the consolidated balance sheets and carried at their redemption value, which is fair value. Any change in the fair value is recognized through retained earnings as if the balance sheet date was also the redemption date.
Held-for-sale Business and Discontinued Operations	We report a business as held-for-sale when certain criteria are met, which include (1) management has either approved the sale or is in the process of obtaining approval to sell the business and is committed to a formal plan to sell the business, (2) the business is available for immediate sale in its present condition, (3) the business is being actively marketed for sale at a price that is reasonable in relation to its current fair value, and (4) the sale is anticipated to occur within the next 12 months, among other specified criteria. A business classified as held-for-sale is recorded at the lower of its carrying amount or estimated fair value less costs to sell. If the carrying amount of the business exceeds its estimated fair value, a loss is recognized. Assets and liabilities related to the businesses classified as held-for-sale are separately reported in our Consolidated Balance Sheets beginning in the period in which the business is classified as held-for-sale. Refer to Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations" for further information regarding our held-for-sale business.Disposals that represent strategic shifts that have or will have a major effect on our operations and financial results are reported as discontinued operations which requires the restatement of the comparatives reflected on our consolidated financial statements.
New Accounting Standards Adopted and Recently Issued Accounting Pronouncements Not Yet Adopted	New Accounting Standards Adopted in 2020 Accounting Standards Update ("ASU") 2020-10 – Codification Improvements In October 2020, the Financial Accounting Standards Board ("FASB") issued ASU 2020-10, which (1) removes references to various FASB Concepts Statements, (2) situates all disclosure guidance in the appropriate disclosure section of the Codification, and (3) makes other improvements and technical corrections to the Codification, with these amendments being applied retrospectively. We early adopted this guidance and that adoption did not have a material impact on our consolidated financial statements and disclosures. ASU 2020-09 – Amendments to SEC Paragraphs Pursuant to SEC Release No. 33-10762 In October 2020, the FASB issued ASU 2020-09, which amends and supersedes various SEC paragraphs included in a number of Codification Topics pursuant to the issuance of the SEC's Release No. 33-10762. Through Release No. 33-10762, which was issued in March 2020, the SEC made amendments to the financial disclosure requirements in Regulation S-X for guarantors and issuers of guaranteed securities registered or being registered, and issuers’ affiliates whose securities collateralize securities registered or being registered, to improve those requirements for both investors and registrants. The changes made by the SEC are intended to (1) provide investors with material information given the specific facts and circumstances, (2) make the disclosures easier to understand, and (3) reduce the costs and burdens to registrants. The amended rules in Release No. 33-10762 became effective on January 4, 2021, although early compliance was permitted. We elected early compliance with the new rules subsequent to their issuance. Because the amendments made by the FASB in this ASU are designed to ensure alignment of the relevant SEC paragraphs in various Codification Topics with the amended rules in Release No. 33-10762, the amendments did not have a material impact on our disclosures, since we already elected early compliance with the amended rules in Release No. 33-10762. ASU 2020-04 and ASU 2021-01– Reference Rate Reform In March 2020, the FASB issued ASU 2020-04, which is codified in Accounting Standards Codification ("ASC") 848 and which provides entities with temporary optional expedients and exceptions to the existing US GAAP guidance on contract modifications and hedge accounting to ease the financial reporting burdens related to the expected market transition from the London Inter-bank Offered Rate ("LIBOR") and other inter-bank offered rates to alternative reference rates, such as the Secured Overnight Financing Rate ("SOFR"). Under the provisions of ASU 2020-04, entities can elect not to apply certain modification accounting requirements to contracts affected by reference rate reform, if certain criteria are met. An entity that makes this election would not have to remeasure the contracts at the modification date or reassess a previous accounting determination. Entities can also elect various optional expedients for hedging relationships affected by reference rate reform, if certain criteria are met. Once elected, the amendments in this guidance must be applied prospectively for all eligible contract modifications. Subsequently in January 2021, the FASB issued ASU 2021-01 to refine the scope of ASC 848 and clarify that certain optional expedients and exceptions in ASC 848 for contract modifications and hedge accounting apply to derivatives that are affected by the discounting transition. Specifically, the ASU clarified that certain provisions in ASC 848, if elected by an entity, apply to derivative instruments that use an interest rate for margining, discounting, or contract price alignment that is modified as a result of reference rate reform. The amendments in ASU 2021-01 are effective immediately for all entities and can be applied either on a full retrospective or prospective basis depending on the facts and circumstances. ASU 2020-04 was effective upon issuance and can be applied through to December 31, 2022. We adopted the ASU upon its issuance and as we transition from LIBOR to alternative reference rates, we have elected the temporary optional expedients and exceptions to the existing US GAAP guidance on contract modifications and hedge accounting permitted by the ASU, as appropriate. The adoption of this standard did not have any impact on our consolidated financial statements and disclosures. ASU 2020-03 – Codification Improvements to Financial Instruments In March 2020, the FASB issued ASU 2020-03, which makes narrow-scope improvements to various topics within the codification relating to financial instruments, including the new credit losses standard. The amendments related to certain specific issues covered by the ASU were effective immediately upon the issuance of the ASU, while certain specific issues covered by the ASU and affecting the credit losses standard in ASU 2016-13 were effective in 2020 for those entities that have already adopted ASU 2016-13. We adopted the amendments in this ASU upon its issuance and that adoption did not have a material impact on our consolidated financial statements and the related disclosures. ASUs 2016-13, 2018-19, 2019-04, 2019-05, 2019-10 and 2019-11, Financial Instruments – Credit Losses – Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued ASU 2016-13, which is codified in ASC 326 - Financial Instruments - Credit Losses, amending the guidance on the impairment of financial instruments and significantly changing how entities measure credit losses for most financial assets and certain other financial instruments, including reinsurance balances recoverable on paid and unpaid losses that are not measured at fair value through net earnings. The ASU replaced the “incurred loss” approach that was previously applied to determine credit losses with an “expected loss” model for financial instruments measured at amortized cost. Under the "expected loss" model, the estimate of expected credit losses should consider historical information, current information, as well as reasonable and supportable forecasts, including estimates of prepayments. The expected credit losses and subsequent adjustments to such losses are recorded through an allowance account that is deducted from the amortized cost basis of the financial asset, with the net carrying value of the financial asset presented on the consolidated balance sheet at the amount expected to be collected. ASU 2016-13 also amends the other-than-temporary impairment ("OTTI") model that was previously applicable to AFS debt securities, with the new approach now requiring the recognition of impairments relating to credit losses through an allowance account and limiting the amount of credit loss to the difference between a security’s amortized cost basis and its fair value. This revised approach records the full effect of reversals of any credit losses in current period earnings, compared to previous guidance where this reversal was amortized over the lifetime of the security. Under this revised approach, the length of time a security has been in an unrealized loss position will no longer be considered in determining whether to record a credit loss. In addition, the historical and implied volatility of the fair value of a security and recoveries or declines in fair value after the balance sheet date will no longer be considered when making a determination of whether a credit loss exists. We adopted ASU 2016-13 and all the related amendments on January 1, 2020 using the modified retrospective approach for our financial instruments carried at amortized cost, and prospectively for our AFS debt securities as required by the standard, resulting in an overall reduction in retained earnings of $6.1 million as summarized below: •A cumulative effect adjustment of $3.0 million relating to our financial instruments carried at amortized cost, which primarily relates to our insurance balances recoverable on paid and unpaid losses. We already carried significant specific allowances for credit losses of $147.6 million on our reinsurance balances recoverable on paid and unpaid losses, relating primarily to our Non-life Run-off segment and therefore the adoption of this standard did not have a material impact on our balance sheet; and •$3.1 million related to our AFS debt securities whose fair values were less than their amortized cost basis. Recently Issued Accounting Pronouncements Not Yet Adopted ASU 2020-08 – Codification Improvements to Subtopic 310-20 - Receivables - Nonrefundable Fees and Other Costs In October 2020, the FASB issued ASU 2020-08 to clarify that an entity should re-evaluate whether a callable debt security is within the scope of ASC 310-20-35-33 during each reporting period. All entities are required to apply the amendments in this ASU on a prospective basis as of the beginning of the period of adoption for existing or newly purchased callable debt securities. The amendments in this ASU are effective for interim and annual reporting periods beginning after December 15, 2020, and early adoption is not permitted. We do not expect the adoption of this guidance to have a material impact on our consolidated financial statements and the related disclosures. ASU 2020-06 – Accounting for Convertible Instruments and Contracts in an Entity's Own Equity In August 2020, the FASB issued ASU 2020-06, which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts in an entity's own equity. For convertible instruments, the ASU eliminates two of the three accounting models in ASC 470-20 that require separate accounting for embedded conversion features. The ASU also simplifies an issuer's application of the derivatives scope exception in ASC 815-40 for contracts in its own equity and removes some of the conditions that preclude a freestanding contract from being classified in equity, thereby allowing more of such contracts to qualify for equity classification. The amendments in this ASU are effective for interim and annual reporting periods beginning after December 15, 2021 and, although early adoption is permitted, the amendments may not be adopted earlier than during interim and annual reporting periods beginning after December 15, 2020. In addition, the FASB specified that an entity should adopt the guidance as of the beginning of its annual reporting period through either a modified retrospective method of transition or a fully retrospective method of transition. We do not expect the adoption of this guidance to have a material impact on our consolidated financial statements and the related disclosures. ASU 2020-01 - Clarifying the Interactions between ASC 321, ASC 323 and ASC 815 In January 2020, the FASB issued ASU 2020-01 to clarify the interaction of the accounting for equity securities under ASC 321 and investments accounted for under the equity method of accounting in ASC 323 and the accounting for certain forward contracts and purchased options accounted for under ASC 815. With respect to the interactions between ASC 321 and ASC 323, the amendments clarify that an entity should consider observable transactions that require it to either apply or discontinue the equity method of accounting when applying the measurement alternative in ASC 321, immediately before applying or upon discontinuing the equity method of accounting. With respect to forward contracts or purchased options to purchase securities, the amendments clarify that when applying the guidance in ASC 815-10-15-141(a), an entity should not consider whether upon the settlement of the forward contract or exercise of the purchased option, individually or with existing investments, the underlying securities would be accounted for under the equity method in ASC 323 or the fair value option in accordance with ASC 825. The ASU is effective for interim and annual reporting periods beginning after December 15, 2020, although early adoption is permitted, including adoption in any interim period. We do not expect the adoption of this guidance to have a material impact on our consolidated financial statements and disclosures. ASU 2019-12 - Simplifying the Accounting for Income Taxes In December 2019, the FASB issued ASU 2019-12 which removes certain exceptions for (1) recognizing deferred taxes for investments, (2) performing intraperiod tax allocation, and (3) calculating income taxes in interim periods. The ASU also adds guidance to reduce complexity in certain areas, including recognizing deferred taxes for tax goodwill and allocating income taxes to a legal entity that is not subject to income taxes. The ASU is effective for interim and annual reporting periods beginning after December 15, 2020, although early adoption is permitted, including adoption in any interim period. We do not expect the adoption of this guidance to have a material impact on our consolidated financial statements and disclosures.

Business Acquisitions (Tables)

12 Months Ended

Dec. 31, 2020

Morse TEC

Business Acquisition [Line Items]

Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed as of Date of Acquisition


ASSETS
Cash and cash equivalents	$	171,412

Deferred tax assets	140,000
Other assets - insurance balances receivable	371,116

TOTAL ASSETS	682,528
LIABILITIES
Defendant asbestos and environmental liabilities	662,507


Other liabilities	20,021
TOTAL LIABILITIES	$	682,528
NET ASSETS ACQUIRED AT FAIR VALUE	—

Pro Forma Condensed Combined Statement of Earnings

The table below summarizes the results of the Morse TEC operations, which were included in our consolidated statement of earnings from the acquisition date to December 31, 2019:


Net investment income	$	488

General and administrative expenses	(1,459)
Other expenses	(1,512)
Net loss	$	(2,483)

Maiden Re

Business Acquisition [Line Items]

Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed as of Date of Acquisition


ASSETS
Fixed maturities, trading, at fair value	$	1,098,593
Short-term investments, trading, at fair value	3,508
Total investments	1,102,101
Cash and cash equivalents	12,035
Restricted cash and cash equivalents	26,871
Premiums receivable	138,378
Prepaid reinsurance premiums	3,257
Reinsurance balances recoverable	87,018


Other assets	96,669
TOTAL ASSETS	$	1,466,329
LIABILITIES
Losses and LAE	$	1,027,367
Unearned premiums	85,696

Other liabilities	56,618
TOTAL LIABILITIES	1,169,681
NET ASSETS ACQUIRED AT FAIR VALUE	$	296,648

Pro Forma Condensed Combined Statement of Earnings

The table below summarizes the results of the Maiden Re North America operations, which were included in our consolidated statement of earnings from the acquisition date to December 31, 2018:






Net investment income	$	675
Net unrealized gains	3,749
General and administrative expenses	(435)

Net earnings	$	3,989

Purchase Price and Fair Value of Assets Acquired

The components of the consideration paid to acquire all of the outstanding shares of Maiden Re North America were as follows:


Cash paid	$	286,375
Adjustment for the fair value of preexisting relationships	10,273
Total purchase price	$	296,648
Net assets acquired at fair value (including preexisting relationships)	$	296,648
Excess of purchase price over fair value of net assets acquired	$	—

KaylaRe

Business Acquisition [Line Items]

Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed as of Date of Acquisition


ASSETS	Carrying value		Fair value		Loss on deemed settlement
Funds held by reinsured companies	$	386,793	$	386,793	$	—
Deferred acquisition costs/Value of business acquired	33,549		40,268		6,719
TOTAL ASSETS	420,342		427,061		6,719
LIABILITIES
Losses and LAE	339,747		333,205		(6,542)
Unearned premiums	105,602		105,602		—
Insurance and reinsurance balances payable	25,897		23,559		(2,338)
Other liabilities	1,864		1,864		—
TOTAL LIABILITIES	473,110		464,230		(8,880)
NET ASSETS (LIABILITIES)	$	(52,768)	$	(37,169)	$	15,599


ASSETS
Fixed maturities, trading, at fair value	$	126,393
Other investments, at fair value	626,476
Total investments	752,869
Cash and cash equivalents	5,657
Premiums receivable	10,965

Deferred acquisition costs	275
Other assets	614
TOTAL ASSETS	$	770,380
LIABILITIES
Losses and LAE	$	4,059
Unearned premiums	10,984
Insurance and reinsurance balances payable	13
Other liabilities	9,004
TOTAL LIABILITIES	24,060
NET ASSETS ACQUIRED AT FAIR VALUE	$	746,320

Pro Forma Condensed Combined Statement of Earnings

The table below summarizes the results of the KaylaRe operations, which are included in our consolidated statement of earnings from the acquisition date to December 31, 2018:


Premiums earned	$	13,627
Incurred losses and LAE	(12,364)
Acquisition costs	(341)
Underwriting income	922
Net investment income	3,096
Net unrealized gains	(47,769)
General and administrative expenses	(2,164)
Net loss	$	(45,915)

Purchase Price and Fair Value of Assets Acquired

The components of the consideration paid to acquire all of the outstanding shares and warrants of KaylaRe were as follows:


Fair value of Enstar ordinary shares issued	$	414,750
Fair value of previously held equity method investment	336,137
Adjustment for the fair value of preexisting relationships	37,169
Total purchase price	$	788,056
Net assets acquired at fair value (excluding preexisting relationships)	$	746,320
Excess of purchase price over fair value of net assets acquired	$	41,736


Number of Enstar ordinary shares issued	2,007,017
Closing price of Enstar voting ordinary shares as of May 14, 2018	$	206.65
Fair value of Enstar ordinary shares issued to shareholders of KaylaRe	$	414,750


Carrying value of previously held equity method investment prior to the close of the transaction	$	320,130
Price-to-book multiple	1.05
Fair value of previously held equity method investment prior to the close of the transaction	$	336,137

Gain recognized on remeasurement of previously held equity method investment to fair value	$	16,007

Significant New Business (Tables)

12 Months Ended

Dec. 31, 2020

Business Combinations [Abstract]

Summary Of Significant New Business

The table below sets forth a summary of significant new business that we have completed between January 1, 2018 and December 31, 2020:


Transaction	Date Completed	Total Assets Assumed		Deferred Charge Asset (1)		Total Liabilities Assumed		Net Fair Value Adjustment (2)		Primary Nature of Business



Hannover Re	August 6, 2020	$	182,498	N/A		$	209,713	$	(27,215)	U.S. asbestos, environmental and workers' compensation liabilities
Munich Re	July 1, 2020	$	100,956	N/A		$	100,956	N/A		Australian public liability, professional liability and builders' warranty liabilities
AXA Group (3)	June 1, 2020	$	179,681	N/A		$	179,681	N/A		U.S. construction general liability
Aspen	June 1, 2020	$	770,000	$	11,746	$	781,746	N/A		Diversified mix of property, liability and specialty lines of business across the U.S., U.K. and Europe
Lyft	March 31, 2020	$	465,000	N/A		$	465,000	N/A		U.S. motor
Zurich (3)	October 1, 2019	$	507,061	$	115,815	$	622,876	N/A		U.S. asbestos and environmental liability
Maiden Re Bermuda	August 5, 2019	$	445,000	$	85,183	$	530,183	N/A		U.S. workers' compensation and General Casualty
Amerisure	April 11, 2019	$	45,463	$	2,873	$	48,336	N/A		U.S. construction defect
AmTrust	February 14, 2019	$	1,143,949	$	20,633	$	1,164,582	N/A		Lloyd's property, professional, marine, non-marine, affinity annual, extended warranty and political
Allianz SE	December 31, 2018	$	70,000	N/A		$	70,000	N/A		Asbestos and environmental
Maiden Re Bermuda	December 27, 2018	$	70,425	$	1,704	$	72,129	N/A		U.S. workers' compensation and motor
Coca-Cola	August 1, 2018	$	103,617	$	17,208	$	120,825	N/A		U.S. workers' compensation, auto liability, general and product liability
Zurich Australia	February 23, 2018	$	268,657	N/A		$	280,764	$	(12,107)	Australian motor
Neon	February 16, 2018	$	525,673	N/A		$	546,298	$	(20,625)	Medical malpractice, general liability, professional indemnity and marine
Novae	January 29, 2018	$	1,095,730	N/A		$	1,163,198	$	(67,468)	Financial, casualty, marine and energy, professional indemnity, aviation, motor and property

The table below sets forth a summary of significant new business that we have signed or completed between January 1, 2021 and March 1, 2021:

Transaction

Date Completed

Initial Estimate of Liabilities Assumed

Primary Nature of Business

AXA Group(4)

N/A - Announced February 25, 2021

1,395,000

Diversified mix of global casualty and professional lines

ProSight (4)

N/A - Announced January 15, 2021

500,000

U.S. discontinued workers' compensation and excess workers' compensation lines of business and adverse development cover on a diversified mix of general liability classes of business

CNA (4)

February 5, 2021

690,000

U.S. excess workers' compensation

Liberty Mutual (4)

January 8, 2021

420,000

U.S. energy liability, construction liability and homebuilders liability

(1) Where the estimated ultimate losses payable exceed the premium consideration received at the inception of the agreement, a deferred charge asset is recorded.

(2) When the fair value option is elected for any retroactive reinsurance agreement, an initial net fair value adjustment is recorded at the inception of the agreement.

Divestitures, Held-For-Sale Businesses and Discontinued Operations (Tables)

12 Months Ended

Dec. 31, 2020

Discontinued Operations and Disposal Groups [Abstract]

Financial Information of Held-For-Sale Business

The following table summarizes the components of Northshore's assets and liabilities held-for-sale on our consolidated balance sheet as of December 31, 2020:


	December 31, 2020
ASSETS

Short-term investments, AFS, at fair value	$	1,720
Fixed maturities, trading, at fair value	154,026

Fixed maturities, AFS, at fair value	7,483


Other investments, at fair value	9,897


Total investments	173,126
Cash and cash equivalents	71,156
Restricted cash and cash equivalents	152,044
Premiums receivable	62,392


Reinsurance balances recoverable on paid and unpaid losses	37,341


Funds held by reinsured companies	32,226


Other assets	182,993
TOTAL ASSETS HELD-FOR-SALE	$	711,278

LIABILITIES
Losses and loss adjustment expenses	$	254,149



Insurance and reinsurance balances payable	12,393

Debt obligations	39,850
Other liabilities	177,265
TOTAL LIABILITIES HELD-FOR-SALE	$	483,657

NET ASSETS HELD-FOR-SALE	$	227,621


	December 31, 2019 (1)
ASSETS


Fixed maturities, trading, at fair value	$	202,994

Fixed maturities, AFS, at fair value	375,337

Equities, at fair value	3,000
Other investments, at fair value	6,389


Total investments	587,720
Cash and cash equivalents	78,613
Restricted cash and cash equivalents	5,815
Premiums receivable	99,367
Deferred tax assets	15,191

Reinsurance balances recoverable on paid and unpaid losses	530,604


Funds held by reinsured companies	35,861
Deferred acquisition costs	36,992
Goodwill and intangible assets	24,900
Other assets	59,707
TOTAL ASSETS HELD-FOR-SALE	$	1,474,770

LIABILITIES
Losses and loss adjustment expenses	$	836,761


Unearned premiums	218,166
Insurance and reinsurance balances payable	22,453


Other liabilities	131,151
TOTAL LIABILITIES HELD-FOR-SALE	$	1,208,531

NET ASSETS HELD-FOR-SALE	$	266,239

The following table summarizes the components of net earnings (loss) from discontinued operations, net of income taxes, related to StarStone U.S., on the consolidated statements of earnings for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
INCOME
Net premiums earned	$	291,326	$	350,814	$	199,796

Net investment income	12,849		15,606		10,572
Net realized and unrealized gains	5,431		19,385		(5,352)
Other income	49		9		10
	309,655		385,814		205,026
EXPENSES
Net incurred losses and loss adjustment expenses	191,844		258,396		130,303
Acquisition costs	57,640		65,342		14,935
General and administrative expenses	60,236		60,003		58,590
Interest expense	2,066		2,600		2,120
Net foreign exchange (gains) losses	(13)		33		24
	311,773		386,374		205,972
EARNINGS (LOSS) BEFORE INCOME TAXES	(2,118)		(560)		(946)
Income tax benefit	2,255		7,935		2,435

NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES, BEFORE GAIN ON SALE	$	137	$	7,375	$	1,489

DISPOSAL
Consideration received	$	281,989	$	—	$	—
Less: Carrying value of subsidiary	(277,697)		—		—

Add: Net realized gains on AFS securities and cumulative currency translation adjustments previously recognized in AOCI	11,822		—		—
Gain on sale of subsidiary	$	16,114	$	—	$	—

NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES	$	16,251	$	7,375	$	1,489
Net loss (earnings) from discontinued operations attributable to noncontrolling interest	(8,717)		(3,025)		(611)
NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$	7,534	$	4,350	$	878


	2020		2019		2018
Total Income	$	11,911	$	10,672	$	98,402
Total Expenses (1)	(16,397)		62,515		113,952
Net Earnings (Loss)	$	28,308	$	(51,843)	$	(15,550)

(1) For the year ended December 31, 2020, negative total expenses were driven by favorable loss development on the losses and LAE reserves ceded by StarStone U.S. to our subsidiaries.

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

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Investments, Debt and Equity Securities [Abstract]

Investments (Tables)

12 Months Ended

Dec. 31, 2020

Estimated Fair Values of Investments in Fixed Maturity Investments, Short-Term Investments and Equities, Trading Securities


	2020
	Short-term investments, trading		Short-term investments, AFS		Fixed maturities, trading		Fixed maturities, AFS		Fixed maturities, funds held - directly managed		Total
U.S. government and agency	$	—	$	243,556	$	123,874	$	474,442	$	109,176	$	951,048
U.K. government	—		—		37,508		13,574		—		51,082
Other government	3,424		3,213		327,437		146,914		21,165		502,153
Corporate	1,705		17,026		3,227,726		1,920,323		519,952		5,686,732
Municipal	—		—		79,959		30,032		52,678		162,669
Residential mortgage-backed	—		—		154,471		328,871		70,603		553,945
Commercial mortgage-backed	—		—		347,225		276,488		230,377		854,090
Asset-backed	—		—		296,692		204,456		56,312		557,460
Total fixed maturity and short-term investments	$	5,129	$	263,795	$	4,594,892	$	3,395,100	$	1,060,263	$	9,319,179


	2019
	Short-term investments, trading		Short-term investments, AFS		Fixed maturities, trading		Fixed maturities, AFS		Fixed maturities, funds held - directly managed		Total
U.S. government and agency	$	—	$	111,583	$	208,296	$	269,661	$	106,537	$	696,077
U.K. government	24,411		1,069		122,012		14,280		—		161,772
Other government	21,958		387		575,017		84,760		20,734		702,856
Corporate	5,121		13,915		3,959,288		866,557		603,389		5,448,270
Municipal	—		1,381		87,451		2,399		49,456		140,687
Residential mortgage-backed	—		—		215,521		99,188		86,205		400,914
Commercial mortgage-backed	—		—		534,357		49,046		230,343		813,746
Asset-backed	—		—		441,393		152,161		76,681		670,235
Total fixed maturity and short-term investments	$	51,490	$	128,335	$	6,143,335	$	1,538,052	$	1,173,345	$	9,034,557

Summary of Amortized Cost and Estimated Fair Value of Fixed Maturity and Short-term Investments by Contractual Maturity


As of December 31, 2020	Amortized Cost		Fair Value		% of Total Fair Value
One year or less	$	489,559	$	494,490	5.3	%
More than one year through two years	710,621		726,331		7.8	%
More than two years through five years	2,097,923		2,206,020		23.7	%
More than five years through ten years	1,974,838		2,151,191		23.1	%
More than ten years	1,544,533		1,775,652		19.0	%
Residential mortgage-backed	545,628		553,945		5.9	%
Commercial mortgage-backed	828,155		854,090		9.2	%
Asset-backed	567,638		557,460		6.0	%
	$	8,758,895	$	9,319,179	100.0	%

Credit Ratings Company's Fixed Maturity and Short-Term Investments Available-for-Sale


	Amortized Cost		Fair Value		% of Total		AAA Rated			AA Rated			A Rated			BBB Rated			Non- Investment Grade			Not Rated

U.S. government and agency	$	935,014	$	951,048	10.2	%	$	951,048		$	—		$	—		$	—		$	—		$	—
U.K. government	46,988		51,082		0.6	%	—			43,199			7,883			—			—			—
Other government	463,765		502,153		5.4	%	244,041			159,095			42,337			51,413			5,267			—
Corporate	5,226,238		5,686,732		61.0	%	172,718			607,796			2,646,602			1,960,971			287,363			11,282
Municipal	145,469		162,669		1.7	%	8,270			78,585			55,631			20,183			—			—
Residential mortgage-backed	545,628		553,945		5.9	%	544,545			—			2,195			2,615			2,472			2,118
Commercial mortgage-backed	828,155		854,090		9.2	%	591,396			115,114			74,615			61,730			3,961			7,274
Asset-backed	567,638		557,460		6.0	%	239,733			84,058			119,757			89,898			24,014			—
Total	$	8,758,895	$	9,319,179	100.0	%	$	2,751,751		$	1,087,847		$	2,949,020		$	2,186,810		$	323,077		$	20,674
% of total fair value							29.5		%	11.7		%	31.6		%	23.5		%	3.5		%	0.2		%

Amortized Cost and Estimated Fair Values of Company's Fixed Maturity and Short-Term Investments Classified as Available-for-Sale


					Gross Unrealized Losses
2020	Amortized Cost		Gross Unrealized Gains		Non-Credit Related Losses		Allowance for Credit Losses(1)		Fair Value
U.S. government and agency	$	715,527	$	3,305	$	(834)	$	—	$	717,998
U.K. government	12,494		1,080		—		—		13,574
Other government	142,459		7,721		(53)		—		150,127
Corporate	1,873,184		65,913		(1,567)		(181)		1,937,349
Municipal	28,881		1,155		(4)		—		30,032
Residential mortgage-backed	326,268		3,292		(689)		—		328,871
Commercial mortgage-backed	273,516		5,202		(2,097)		(133)		276,488
Asset-backed	204,312		846		(694)		(8)		204,456
	$	3,576,641	$	88,514	$	(5,938)	$	(322)	$	3,658,895

(1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 1 - "Significant Accounting Policies" for further details.

The amortized cost, unrealized gains and losses and fair values of our short-term and fixed maturity investments classified as AFS as of December 31, 2019 were as follows:


2019	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses Non-OTTI		Fair Value
U.S. government and agency	$	381,488	$	78	$	(322)	$	381,244
U.K. government	15,067		282		—		15,349
Other government	84,116		1,119		(88)		85,147
Corporate	880,667		3,739		(3,934)		880,472
Municipal	3,770		12		(2)		3,780
Residential mortgage-backed	99,646		221		(679)		99,188
Commercial mortgage-backed	49,219		30		(203)		49,046
Asset-backed	152,153		127		(119)		152,161
	$	1,666,126	$	5,608	$	(5,347)	$	1,666,387


		12 Months or Greater				Less Than 12 Months				Total
2020		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
	U.S. government and agency	$	—	$	—	$	55,839	$	(834)	$	55,839	$	(834)
	UK government	—		—		—		—		—		—
	Other government	—		—		7,971		(53)		7,971		(53)
	Corporate	—		—		199,048		(1,224)		199,048		(1,224)
	Municipal	—		—		1,690		(4)		1,690		(4)
	Residential mortgage-backed	4,626		(125)		79,149		(564)		83,775		(689)
	Commercial mortgage-backed	38		(38)		67,094		(1,562)		67,132		(1,600)
	Asset-backed	—		—		116,827		(564)		116,827		(564)
Total short-term and fixed maturity investments		$	4,664	$	(163)	$	527,618	$	(4,805)	$	532,282	$	(4,968)


		12 Months or Greater				Less Than 12 Months				Total
2019		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
	U.S. government and agency	$	—	$	—	$	193,574	$	(322)	$	193,574	$	(322)

	Other government	1,080		(23)		37,796		(65)		38,876		(88)
	Corporate	2,754		(306)		338,965		(3,628)		341,719		(3,934)
	Municipal	128		—		761		(2)		889		(2)
	Residential mortgage-backed	—		—		52,005		(679)		52,005		(679)
	Commercial mortgage-backed	—		—		35,777		(203)		35,777		(203)
	Asset-backed	—		—		101,591		(119)		101,591		(119)
Total short-term and fixed maturity investments		$	3,962	$	(329)	$	760,469	$	(5,018)	$	764,431	$	(5,347)

Summary of Allowance for Credit Losses

The following table provides a reconciliation of the beginning and ending allowance for credit losses on our AFS debt securities:


	December 31, 2020
	Other government		Corporate		Residential mortgage-backed		Commercial mortgage backed		Asset-backed		Total
Allowance for credit losses, beginning of year	$	—	$	—	$	—	$	—	$	—	$	—
Cumulative effect of change in accounting principle	(22)		(2,987)		—		(50)		—		(3,059)
Allowances for credit losses on securities for which credit losses were not previously recorded	—		(10,748)		(2)		(675)		(142)		(11,567)
Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets	—		—		—		—		—		—
Reductions for securities sold during the year	22		2,545		—		—		—		2,567
Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis	—		—		—		—		—		—
(Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period	—		11,009		2		592		134		11,737


Allowance for credit losses, end of year	$	—	$	(181)	$	—	$	(133)	$	(8)	$	(322)

Schedule Of Equity Securities

The following table summarizes our equity investments classified as trading as of December 31, 2020 and 2019:


	2020		2019
Publicly traded equity investments in common and preferred stocks	$	260,767	$	327,875
Exchange-traded funds	311,287		133,047
Privately held equity investments in common and preferred stocks	274,741		265,799
	$	846,795	$	726,721

Other Investments

The following table summarizes our other investments carried at fair value as of December 31, 2020 and 2019:


	2020		2019
Hedge funds	$	2,638,339	$	1,121,904
Fixed income funds	552,541		481,039
Private equity funds	363,103		323,496
Private credit funds	192,319		—
Equity funds	190,767		410,149
CLO equity funds	166,523		87,509
CLO equities	128,083		87,555
Others	12,359		6,379
	$	4,244,034	$	2,518,031

The table below details the estimated date by which proceeds would be received if we had provided notice of our intent to redeem or initiated a

sales process as of December 31, 2020:


	Less than 1 Year		1-2 years		2-3 years		More than 3 years		Not Eligible/ Restricted		Total		Redemption Frequency
Hedge funds	$	2,590,164	$	—	$	—	$	—	$	48,175	$	2,638,339	Monthly to Bi-annually
Fixed income funds	537,055		—		—		—		15,486		552,541		Daily to Quarterly
Equity funds	190,767		—		—		—		—		190,767		Daily to Quarterly
Private equity funds	—		—		—		—		363,103		363,103		N/A
CLO equity funds	94,313		61,741		10,469		—		—		166,523		Quarterly to Bi-annually
CLO equities	128,083		—		—		—		—		128,083		Daily to Quarterly
Private credit funds	—		9,250				—		183,069		192,319		N/A
Other									12,359		12,359		N/A
	$	3,540,382	$	70,991	$	10,469	$	—	$	622,192	$	4,244,034

Equity Method Investments

The table below shows our equity method investments as of December 31, 2020 and 2019:


	2020				2019
	Ownership %		Carrying Value		Ownership %		Carrying Value
Enhanzed Re	47.4	%	$	330,289	47.4	%	$	182,856
Citco (1)	31.9	%	53,022		31.9	%	51,742
Monument Re (2)	20.0	%	193,716		20.0	%	60,598
Clear Spring	—	%	—		20.0	%	10,645
Core Specialty	25.2	%	235,000		—	%	—
Other	27%		20,268		30%		20,436

			$	832,295			$	326,277

(2) We own 20.0% of the common shares in Monument Re as well as different classes of preferred shares which have fixed dividend yields and whose balances are included in the Investment amount.

Funds Held, Directly Managed, Carrying Values of Assets

The following table summarizes the components of the funds held - directly managed as of December 31, 2020 and 2019:


	2020		2019
Fixed maturity investments, trading	$	1,060,263	$	1,173,345
Cash and cash equivalents	9,067		10,296
Other assets	5,560		3,911
	$	1,074,890	$	1,187,552

Funds Held, Directly Managed, Fair Value To Amortized Cost

The following table summarizes the short-term and fixed maturity investment components of funds held - directly managed as of December 31, 2020 and 2019:


	2020						2019
	Funds held - Directly Managed - Fair Value Option		Funds held - Directly Managed - Variable Return		Total		Funds held - Directly Managed - Fair Value Option		Funds held - Directly Managed - Variable Return		Total
Short-term and fixed maturity investments, at amortized cost	$	106,938	$	859,403	$	966,341	$	185,859	$	940,194	$	1,126,053
Net unrealized gains (losses):
Change in fair value - fair value option accounting	9,693		—		9,693		5,438		—		5,438
Change in fair value - embedded derivative accounting	—		84,229		84,229		—		41,854		41,854
Short-term and fixed maturity investments within funds held - directly managed, at fair value	$	116,631	$	943,632	$	1,060,263	$	191,297	$	982,048	$	1,173,345

Investment Income

Major categories of net investment income for the years ended December 31, 2020, 2019 and 2018 are summarized as follows:


	2020		2019		2018
Fixed maturity investments	$	198,988	$	217,886	$	178,213
Short-term investments and cash and cash equivalents	4,843		15,609		11,692
Funds held	33,920		22,580		11,640
Funds held – directly managed	34,563		38,173		37,623
Investment income from fixed maturities and cash and cash equivalents	272,314		294,248		239,168
Equity investments	19,240		16,671		5,397
Other investments	27,153		11,792		26,214

Investment income from equities and other investments	46,393		28,463		31,611
Gross investment income	318,707		322,711		270,779
Investment expenses	(15,890)		(14,440)		(9,081)
Net investment income	$	302,817	$	308,271	$	261,698

Realized Gain (Loss) on Investments

Components of net realized and unrealized gains (losses) for the years ended December 31, 2020, 2019 and 2018 were as follows:


	2020		2019		2018
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, AFS	$	26,313	$	4,844	$	27
Gross realized losses on fixed maturity securities, AFS	(7,801)		(905)		(90)
Decrease in allowance for expected credit losses on fixed maturity securities, AFS	170		—		—
Net realized gains (losses) on fixed maturity securities, trading	126,945		81,011		(27,408)
Net realized gains (losses) on fixed maturity securities in funds held - directly managed	8,798		1,495		(3,940)
Net realized gains (losses) on equity investments	24,282		(374)		4,016
Net realized investment gains on investment derivatives	144		—		—
Total net realized gains (losses) on sale	178,851		86,071		(27,395)
Net unrealized gains (losses):
Fixed maturity securities, trading	101,022		341,130		(159,594)
Fixed maturity securities in funds held - directly managed	50,837		88,053		(46,257)
Equity investments	(25,752)		55,359		(9,831)
Other investments	1,336,343		441,702		(164,455)
Investment derivatives	718		(349)		—


Total net unrealized gains (losses)	1,463,168		925,895		(380,137)
Net realized and unrealized gains (losses)	$	1,642,019	$	1,011,966	$	(407,532)

Unrealized Gain (Loss) on Investments

Components of net realized and unrealized gains (losses) for the years ended December 31, 2020, 2019 and 2018 were as follows:


	2020		2019		2018
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, AFS	$	26,313	$	4,844	$	27
Gross realized losses on fixed maturity securities, AFS	(7,801)		(905)		(90)
Decrease in allowance for expected credit losses on fixed maturity securities, AFS	170		—		—
Net realized gains (losses) on fixed maturity securities, trading	126,945		81,011		(27,408)
Net realized gains (losses) on fixed maturity securities in funds held - directly managed	8,798		1,495		(3,940)
Net realized gains (losses) on equity investments	24,282		(374)		4,016
Net realized investment gains on investment derivatives	144		—		—
Total net realized gains (losses) on sale	178,851		86,071		(27,395)
Net unrealized gains (losses):
Fixed maturity securities, trading	101,022		341,130		(159,594)
Fixed maturity securities in funds held - directly managed	50,837		88,053		(46,257)
Equity investments	(25,752)		55,359		(9,831)
Other investments	1,336,343		441,702		(164,455)
Investment derivatives	718		(349)		—


Total net unrealized gains (losses)	1,463,168		925,895		(380,137)
Net realized and unrealized gains (losses)	$	1,642,019	$	1,011,966	$	(407,532)

Reconciliation to Comprehensive Income


	2020		2019		2018






Included within continuing operations:
Gross realized gains on fixed maturity securities, AFS	$	26,313	$	4,844	$	27
Gross realized losses on fixed maturity securities, AFS	(7,801)		(905)		(90)
Tax effect	(1,623)		—		—
Included within discontinued operations:
Gross realized gains on fixed maturity securities, AFS	1,374		12		—
Gross realized losses on fixed maturity securities, AFS	(120)		(57)		—
Tax effect	(110)		—		—
Total reclassification adjustment for net realized gains (losses) included in net earnings	$	18,033	$	3,894	$	(63)
Included within continuing operations:
Credit recoveries (losses) on fixed maturity securities, AFS	$	170	$	—	$	—
Tax effect	3		—		—
Included within discontinued operations:
Credit recoveries (losses) on fixed maturity securities, AFS	329		—		—
Tax effect	7		—		—
Total reclassification adjustment for change in allowance for credit losses recognized in net earnings	$	509	$	—	$	—

The following table presents details amounts reclassified from accumulated other comprehensive income:


Details about AOCI components	2020	2019	2018	Affected Line Item in Statement where Net Earnings are presented
Unrealized gains (losses) on fixed income available-for-sale investments	18,682	3,894	(63)	Net realized and unrealized gains (losses)
	16,591	—	—	Net earnings from discontinued operations
	35,273	3,894	(63)	Total before tax
	(4,875)	—	—	Income tax (expense)
	30,398	3,894	(63)	Net of tax
Currency translation adjustment on disposal of subsidiary	(34)	—	—	Net earnings from discontinued operations
Total reclassifications for the period, net of tax	30,364	3,894	(63)

Schedule of Carrying Value of Restricted Investments

The carrying value of our restricted assets, including restricted cash of $472.0 million and $346.9 million, as of December 31, 2020 and 2019, respectively, was as follows:


	2020		2019
Collateral in trust for third party agreements	$	4,924,866	$	4,103,847
Assets on deposit with regulatory authorities	131,283		309,659
Collateral for secured letter of credit facilities	104,627		132,670
Funds at Lloyd's (1)	260,914		639,316
	$	5,421,690	$	5,185,492

Derivatives and Hedging Instruments (Tables)

12 Months Ended

Dec. 31, 2020

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Estimated Fair Value and Unrealized Gains (Losses) on Derivative Instruments


	2020						2019
			Fair Value						Fair Value
	Gross Notional Amount		Assets		Liabilities		Gross Notional Amount		Assets		Liabilities
Foreign currency forward - AUD	$	73,852	$	13	$	5,060	$	64,620	$	52	$	2,033
Foreign currency forward - EUR	217,168		205		8,889		112,284		246		1,635
Foreign currency forward - GBP	312,671		951		14,998		318,387		344		7,784
Total qualifying hedges	$	603,691	$	1,169	$	28,947	$	495,291	$	642	$	11,452


	Amount of Gains (Losses) Deferred in AOCI
	2020		2019		2018
Foreign currency forward - AUD	$	(6,792)	$	(722)	$	3,438
Foreign currency forward - EUR	(15,026)		1,817		1,000
Foreign currency forward - GBP	(8,457)		(16,423)		—
Total qualifying hedges	$	(30,275)	$	(15,328)	$	4,438


	December 31, 2020						December 31, 2019
			Fair Value						Fair Value
	Gross Notional Amount		Assets		Liabilities		Gross Notional Amount		Assets		Liabilities
Foreign currency forward - AUD	$	28,848	$	882	$	2,847	$	913	$	839	$	892
Foreign currency forward - CAD	64,224		10		1,764		66,266		10		1,482
Foreign currency forward - EUR	43,531		1,782		41		74,444		507		1,440
Foreign currency forward - GBP	2,731		161		404		11,940		13		292
Total non-qualifying hedges	$	139,334	$	2,835	$	5,056	$	153,563	$	1,369	$	4,106


	Gains (losses) on non-qualifying hedges charged to earnings
	2020		2019		2018
Foreign currency forward - AUD	$	(2,388)	$	1,523	$	4,958
Foreign currency forward - CAD	(879)		(2,079)		9,311
Foreign currency forward - EUR	1,871		1,759		2,296
Foreign currency forward - GBP	(1,558)		12,004		15,078
Net gains (losses) on non-qualifying hedges	$	(2,954)	$	13,207	$	31,643


	December 31, 2020
			Fair Value
	Gross Notional Amount		Assets		Liabilities

Futures contracts - long positions	$	34,502	$	32	$	5
Futures contracts - short positions	(32,316)		6		121
Currency forward contracts - long positions - USD	1,428		—		13
Currency forward contracts - short positions - USD	(3,233)		60		—
Currency forward contracts - long positions - GBP	1,278		19		—
Currency forward contracts - short positions - GBP	(4,418)		12		—
Total	$	(2,759)	$	129	$	139

Derivative Instruments, Gain (Loss)

The following table presents the amounts of the net gains included in earnings related to our credit default swaps, government bond futures contracts and currency forward contracts:


	2020
Credit default swaps	$	181
Futures contracts	(127)
Currency forward contracts	572
Total net gains	$	626

Tabular disclosure of pertinent information about a derivative or group of derivatives on a disaggregated basis, such as for individual instruments, or small groups of similar instruments. May include a combination of the type of instrument, risks being hedged, notional amount, hedge designation, related hedged item, inception date, maturity date, or other relevant item.

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Reinsurance Balances Recoverable on Paid and Unpaid Losses (Tables)

12 Months Ended

Dec. 31, 2020

Summary of Reinsurance Reserves Recoverable

The following tables provide the total reinsurance balances recoverable on paid and unpaid losses.


	December 31, 2020
	Non-life Run-off		StarStone		Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	938,231	$	263,638	$	1,201,869
IBNR	508,082		139,761		647,843
ULAE	16,688		—		16,688
Fair value adjustments - acquired companies	(14,014)		(1,339)		(15,353)
Fair value adjustments - fair value option	(21,427)		—		(21,427)
Total reinsurance reserves recoverable	1,427,560		402,060		1,829,620
Paid losses recoverable	172,309		87,234		259,543
Total	$	1,599,869	$	489,294	$	2,089,163

Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable on paid and unpaid losses	$	1,079,039	$	489,294	$	1,568,333
Reinsurance balances recoverable on paid and unpaid losses - fair value option	520,830		—		520,830
Total	$	1,599,869	$	489,294	$	2,089,163


	December 31, 2019
	Non-life Run-off		Atrium		StarStone		Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	972,293	$	9,011	$	264,131	$	1,245,435
IBNR	673,059		19,286		93,185		785,530

Fair value adjustments - acquired companies	(13,652)		519		(2,122)		(15,255)
Fair value adjustments - fair value option	(88,086)		—		—		(88,086)
Total reinsurance reserves recoverable	1,543,614		28,816		355,194		1,927,624
Paid losses recoverable	181,375		1,541		70,594		253,510
Total	$	1,724,989	$	30,357	$	425,788	$	2,181,134

Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable on paid and unpaid losses	$	1,029,471	$	30,357	$	425,788	$	1,485,616
Reinsurance balances recoverable on paid and unpaid losses - fair value option	695,518		—		—		695,518
Total	$	1,724,989	$	30,357	$	425,788	$	2,181,134


	December 31, 2020
	Gross		Allowance for estimated uncollectible reinsurance		Net		Provisions as a % of Gross
Reinsurers rated A- or above	$	1,464,529	$	60,801	$	1,403,728	4.2	%
Reinsurers rated below A-, secured	608,999		—		608,999		—	%
Reinsurers rated below A-, unsecured	152,757		76,321		76,436		50.0	%
Total	$	2,226,285	$	137,122	$	2,089,163	6.2	%


	December 31, 2019
	Gross		Allowance for estimated uncollectible reinsurance		Net		Provisions as a % of Gross
Reinsurers rated A- or above	$	1,731,270	$	43,427	$	1,687,843	2.5	%
Reinsurers rated below A-, secured	463,840		—		463,840		—	%
Reinsurers rated below A-, unsecured	133,663		104,212		29,451		78.0	%
Total	$	2,328,773	$	147,639	$	2,181,134	6.3	%

The following tables provide a summary of net premiums written and earned for the years ended December 31, 2020, 2019 and 2018:


	2020				2019				2018
	Premiums Written		Premiums Earned		Premiums Written		Premiums Earned		Premiums Written		Premiums Earned
Non-life Run-off
Gross	$	5,191	$	71,522	$	(25,069)	$	197,009	$	(8,910)	$	25,230
Ceded	(2,204)		(12,827)		(269)		(28,513)		(307)		(15,803)
Net	$	2,987	$	58,695	$	(25,338)	$	168,496	$	(9,217)	$	9,427
Atrium
Gross	$	206,656	$	197,492	$	192,373	$	182,678	$	171,494	$	164,428
Ceded	(23,462)		(22,099)		(20,017)		(18,619)		(18,006)		(18,113)
Net	$	183,194	$	175,393	$	172,356	$	164,059	$	153,488	$	146,315
StarStone
Gross	$	326,695	$	441,015	$	472,815	$	549,299	$	622,570	$	647,218
Ceded	(93,493)		(122,900)		(93,292)		(98,187)		(144,561)		(132,055)
Net	$	233,202	$	318,115	$	379,523	$	451,112	$	478,009	$	515,163
Other
Gross	$	13,441	$	19,889	$	18,534	$	20,544	$	32,378	$	25,237
Ceded	—		—		(22)		(164)		(311)		(363)
Net	$	13,441	$	19,889	$	18,512	$	20,380	$	32,067	$	24,874
Total
Gross	$	551,983	$	729,918	$	658,653	$	949,530	$	817,532	$	862,113
Ceded	(119,159)		(157,826)		(113,600)		(145,483)		(163,185)		(166,334)
Net	$	432,824	$	572,092	$	545,053	$	804,047	$	654,347	$	695,779

Reinsurance Balances Recoverable by Reinsurer


	December 31, 2020
	Non-life Run-off		StarStone		Total		% of Total
Top 10 reinsurers	$	1,036,676	$	327,917	$	1,364,593	65.3	%
Other reinsurers > $1 million	539,428		158,174		697,602		33.4	%
Other reinsurers < $1 million	23,765		3,203		26,968		1.3	%
Total	$	1,599,869	$	489,294	$	2,089,163	100.0	%


	December 31, 2019
	Non-life Run-off		Atrium		StarStone		Total		% of Total
Top 10 reinsurers	$	1,154,110	$	22,051	$	295,443	$	1,471,604	67.4	%
Other reinsurers > $1 million	551,636		7,761		129,335		688,732		31.6	%
Other reinsurers < $1 million	19,243		545		1,010		20,798		1.0	%
Total	$	1,724,989	$	30,357	$	425,788	$	2,181,134	100.0	%


	December 31, 2020		December 31, 2019
Information regarding top ten reinsurers:
Number of top 10 reinsurers rated A- or better	7		8
Number of top 10 non-rated reinsurers (1)	3		2

Reinsurers rated A- or better in top 10	$	863,819	$	1,199,479
Non-rated reinsurers in top 10 (1)	500,774		272,125
Total top 10 reinsurance recoverables	$	1,364,593	$	1,471,604

Single reinsurers that represent 10% or more of total reinsurance balance recoverables as of December 31, 2020 and 2019:

Hannover Ruck SE (2)	$	—	$	259,077
Lloyd's Syndicates (3)	$	331,118	$	396,246
Michigan Catastrophic Claims Association(4)	$	229,374	$	—

(1) The reinsurance balances recoverable from the three and two non-rated top 10 reinsurers as of December 31, 2020 and 2019, respectively, was comprised of:

(3) Lloyd's Syndicates are rated A+ by Standard & Poor's and A by A.M. Best.

(4) U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state.

Summary of Reinsurance Recoverable, Allowance for Credit Loss

The table below provides a reconciliation of the beginning and ending allowance for estimated uncollectible reinsurance balances for the years ended December 31, 2020 and 2019:


	2020		2019
Allowance for estimated uncollectible reinsurance, beginning of year	$	147,639	$	156,732
Cumulative effect of change in accounting principle	(195)		—
Effect of exchange rate movement	700		(887)
Current period change in the allowance	(381)		2,077
Write-offs charged against the allowance	(9,625)		(9,871)
Recoveries collected	(1,016)		(412)
Allowance for estimated uncollectible reinsurance, end of year	$	137,122	$	147,639

Deferred Charge Assets and Deferred Gain Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Deferred Gain Liabilities

Deferred Charge Assets

The following table presents a reconciliation of the deferred charge assets for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Beginning carrying value	$	272,462	$	86,585	$	80,192
Recorded during the year	11,746		224,504		20,174
Amortization	(45,606)		(38,627)		(13,781)

Ending carrying value	$	238,602	$	272,462	$	86,585


	2020		2019
Beginning carrying value	$	12,875	$	—
Recorded during the year	9,365		13,758
Amortization	(2,360)		(883)

Ending carrying value	$	19,880	$	12,875

Losses and Loss Adjustment Expenses (Tables)

12 Months Ended

Dec. 31, 2020

Total Losses and Loss Adjustment Expense Liabilities, and Reconciliation of Beginning and Ending Balances

The following tables summarize the liability for losses and LAE by segment and for our other activities.


	2020
	Non-life Run-off		StarStone		Other		Total
Outstanding losses	$	4,440,425	$	677,220	$	10,204	$	5,127,849
IBNR	4,641,500		615,963		20,040		5,277,503
Fair value adjustments - acquired companies	(142,854)		(329)		—		(143,183)
Fair value adjustments - fair value option	(54,589)		—		—		(54,589)
ULAE	350,600		35,102		—		385,702
Total	$	9,235,082	$	1,327,956	$	30,244	$	10,593,282

Reconciliation to Consolidated Balance Sheet:
Loss and loss adjustment expenses	$	6,782,162	$	1,327,956	$	30,244	$	8,140,362
Loss and loss adjustment expenses, at fair value	2,452,920		—		—		2,452,920
Total	$	9,235,082	$	1,327,956	$	30,244	$	10,593,282


	2019
	Non-life Run-off		Atrium		StarStone		Other		Total
Outstanding losses	$	4,407,082	$	89,141	$	743,830	$	9,512	$	5,249,565
IBNR	3,945,407		136,543		556,134		13,565		4,651,649
Fair value adjustments- acquired companies	(170,689)		3,700		(522)		—		(167,511)
Fair value adjustments - fair value option	(217,933)		—		—		—		(217,933)
ULAE	331,494		2,288		18,852		—		352,634
Total	$	8,295,361	$	231,672	$	1,318,294	$	23,077	$	9,868,404

Reconciliation to Consolidated Balance Sheet:
Loss and loss adjustment expenses	$	5,674,239	$	231,672	$	1,318,294	$	23,077	$	7,247,282
Loss and loss adjustment expenses, at fair value	2,621,122		—		—		—		2,621,122
Total	$	8,295,361	$	231,672	$	1,318,294	$	23,077	$	9,868,404

The table below provides a consolidated reconciliation of the beginning and ending liability for losses and LAE.


	2020		2019		2018
Balance as of January 1	$	9,868,404	$	9,048,796	$	7,100,488
Less: reinsurance reserves recoverable	1,927,624		1,708,272		1,693,028
Less: net deferred charge assets and gain liabilities on retroactive reinsurance	259,587		86,585		80,192

Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances (1)	643		—		—
Net balance as of January 1	7,680,550		7,253,939		5,327,268
Net incurred losses and LAE:
Current period	405,178		580,074		533,081
Prior periods	10,748		34,105		(209,359)
Total net incurred losses and LAE	415,926		614,179		323,722
Net paid losses:
Current period	(71,989)		(179,461)		(176,172)
Prior periods	(1,413,500)		(1,609,009)		(1,158,614)
Total net paid losses	(1,485,489)		(1,788,470)		(1,334,786)
Effect of exchange rate movement	119,663		47,812		(145,243)
Acquired on purchase of subsidiaries	—		686		1,310,874
Assumed business	2,186,024		1,586,307		1,772,104
Ceded business	(154,926)		(33,260)		—
Reclassification to assets and liabilities held-for-sale	(216,808)		—		—
Net balance as of December 31	8,544,940		7,681,193		7,253,939
Plus: reinsurance reserves recoverable (2)	1,829,620		1,927,624		1,708,272
Plus: net deferred charge assets and gain liabilities on retroactive reinsurance	218,722		259,587		86,585
Balance as of December 31	$	10,593,282	$	9,868,404	$	9,048,796

(2) Net of allowance for estimated uncollectible reinsurance.

The table below provides a reconciliation of the beginning and ending reserves for losses and LAE for the Non-life Run-off segment.


	2020		2019		2018
Balance as of January 1	$	8,295,361	$	7,540,662	$	5,949,472
Less: reinsurance reserves recoverable	1,543,614		1,366,123		1,377,485
Less: net deferred charge assets and gain liabilities on retroactive reinsurance	259,587		86,585		80,192
Plus: cumulative effect of change in accounting principal on allowance for estimated uncollectible reinsurance (1)	703		—		—
Net balance as of January 1	6,492,863		6,087,954		4,491,795
Net incurred losses and LAE:
Current period	30,165		123,559		12,451
Prior periods	14,830		(71,934)		(318,518)
Total net incurred losses and LAE	44,995		51,625		(306,067)
Net paid losses:
Current period	(9,990)		(64,820)		(5)
Prior periods	(1,064,911)		(1,182,804)		(838,812)
Total net paid losses	(1,074,901)		(1,247,624)		(838,817)
Effect of exchange rate movement	94,745		46,472		(132,632)
Acquired on purchase of subsidiaries	—		686		1,111,839
Assumed business	2,186,024		1,586,307		1,761,836
Ceded business	(154,926)		(33,260)		—
Net balance as of December 31	7,588,800		6,492,160		6,087,954
Plus: reinsurance reserves recoverable(2)	1,427,560		1,543,614		1,366,123
Plus: net deferred charge assets and gain liabilities on retroactive reinsurance	218,722		259,587		86,585
Balance as of December 31	$	9,235,082	$	8,295,361	$	7,540,662

(1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details.

(2) Net of allowance for estimated uncollectible reinsurance.

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Balance as of January 1	$	231,672	$	241,284	$	240,873
Less: reinsurance reserves recoverable	28,816		38,768		40,531

Less: cumulative effect of change in accounting principal on allowance for estimated uncollectible reinsurance (1)	851		—		—
Net balance as of January 1	202,005		202,516		200,342
Net incurred losses and LAE:
Current period	93,471		85,027		83,627
Prior periods	(6,245)		(7,751)		(13,817)
Total net incurred losses and LAE	87,226		77,276		69,810
Net paid losses:
Current period	(33,724)		(34,617)		(35,537)
Prior periods	(40,196)		(43,572)		(28,969)
Total net paid losses	(73,920)		(78,189)		(64,506)
Effect of exchange rate movement	1,497		1,253		(3,130)
Reclassification to assets and liabilities held-for-sale	(216,808)		—		—
Net balance as of December 31	—		202,856		202,516
Plus: reinsurance reserves recoverable (2)	—		28,816		38,768
Balance as of December 31	$	—	$	231,672	$	241,284

(1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details.

(2) Net of allowance for estimated uncollectible reinsurance.

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Balance as of January 1	$	1,318,294	$	1,247,989	$	910,143
Less: reinsurance reserves recoverable	355,194		303,381		275,012

Less: cumulative effect of change in accounting principal on allowance for estimated uncollectible reinsurance (1)	495		—		—
Net balance as of January 1	962,605		944,608		635,131
Net incurred losses and LAE:
Current period	263,562		354,884		422,191
Prior periods	3,176		114,356		120,889
Total net incurred losses and LAE	266,738		469,240		543,080
Net paid losses:
Current period	(26,831)		(75,458)		(137,390)
Prior periods	(300,037)		(375,377)		(289,981)
Total net paid losses	(326,868)		(450,835)		(427,371)
Effect of exchange rate movement	23,421		87		(9,481)
Acquired on purchase of subsidiaries	—		—		192,981
Assumed business	—		—		10,268
Ceded business	—		—		—
Net balance as of December 31	925,896		963,100		944,608
Plus: reinsurance reserves recoverable (2)	402,060		355,194		303,381
Balance as of December 31	$	1,327,956	$	1,318,294	$	1,247,989

(1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details.

(2) Net of allowance for estimated uncollectible reinsurance.

Schedule of Incurred Losses

The tables below provide the components of net incurred losses and LAE by segment and for our other activities.


	2020
	Non-life Run-off		Atrium		StarStone		Other		Total
Net losses paid	$	1,074,901	$	73,920	$	326,868	$	9,800	$	1,485,489
Net change in case and LAE reserves (1)	(453,080)		7,245		(95,044)		692		(540,187)
Net change in IBNR reserves (2)	(718,414)		6,661		17,654		6,475		(687,624)
Increase (reduction) in estimates of net ultimate losses	(96,593)		87,826		249,478		16,967		257,678

Increase (reduction) in provisions for unallocated LAE (3)	(48,765)		(29)		17,244		—		(31,550)
Amortization of deferred charge assets and deferred gain liabilities (4)	42,640		—		606		—		43,246
Amortization of fair value adjustments (5)	28,667		(571)		(590)		—		27,506
Changes in fair value - fair value option (6)	119,046		—		—		—		119,046
Net incurred losses and LAE	$	44,995	$	87,226	$	266,738	$	16,967	$	415,926


	2019
	Non-life Run-off		Atrium		StarStone		Other		Total
Net losses paid	$	1,247,624	$	78,189	$	450,835	$	11,822	$	1,788,470
Net change in case and LAE reserves (1)	(530,891)		3,534		(4,686)		3,460		(528,583)
Net change in IBNR reserves (2)	(812,699)		(4,782)		22,021		756		(794,704)
Increase (reduction) in estimates of net ultimate losses	(95,966)		76,941		468,170		16,038		465,183

Increase (reduction) in provisions for unallocated LAE (3)	(57,404)		—		902		—		(56,502)
Amortization of deferred charge assets and deferred gain liabilities (4)	37,744		—		—		—		37,744
Amortization of fair value adjustments (5)	50,070		335		168		—		50,573
Changes in fair value - fair value option (6)	117,181		—		—		—		117,181
Net incurred losses and LAE	$	51,625	$	77,276	$	469,240	$	16,038	$	614,179


	2018
	Non-life Run-off		Atrium		StarStone		Other		Total
Net losses paid	$	838,817	$	64,506	$	427,371	$	4,092	$	1,334,786
Net change in case and LAE reserves (1)	(547,420)		6,331		63,861		4,808		(472,420)
Net change in IBNR reserves (2)	(565,385)		4,091		46,501		7,999		(506,794)
Increase (reduction) in estimates of net ultimate losses	(273,988)		74,928		537,733		16,899		355,572

Increase (reduction) in provisions for unallocated LAE (3)	(65,401)		—		5,613		—		(59,788)
Amortization of deferred charge assets and deferred gain liabilities (4)	13,781		—		—		—		13,781
Amortization of fair value adjustments (5)	12,877		(5,118)		(266)		—		7,493
Changes in fair value - fair value option (6)	6,664		—		—		—		6,664
Net incurred losses and LAE	$	(306,067)	$	69,810	$	543,080	$	16,899	$	323,722

(2)Represents the gross change in our actuarial estimates of IBNR, less amounts recoverable.

(3) Represents the change in the estimate of the total future costs to administer the claims.

(4) Relates to the amortization of deferred charge assets and deferred gain liabilities on retroactive reinsurance contracts.

(5) Relates to the amortization of fair value adjustments associated with the acquisition of companies. .

(6) Represents the changes in the fair value of liabilities related to our assumed retroactive reinsurance agreements for which we have elected the fair value option

Net incurred losses and LAE in the Non-life Run-off segment were as follows:


	2020						2019						2018
	Prior Period		Current Period		Total		Prior Period		Current Period		Total		Prior Period		Current Period		Total
Net losses paid	$	1,064,911	$	9,990	$	1,074,901	$	1,182,804	$	64,820	$	1,247,624	$	838,812	$	5	$	838,817
Net change in case and LAE reserves (1)	(449,610)		(3,470)		(453,080)		(553,996)		23,105		(530,891)		(552,124)		4,704		(547,420)
Net change in IBNR reserves (2)	(742,417)		24,003		(718,414)		(847,893)		35,194		(812,699)		(573,127)		7,742		(565,385)
Increase (reduction) in estimates of net ultimate losses	(127,116)		30,523		(96,593)		(219,085)		123,119		(95,966)		(286,439)		12,451		(273,988)

Increase (reduction) in provisions for unallocated LAE (3)	(48,407)		(358)		(48,765)		(57,844)		440		(57,404)		(65,401)		—		(65,401)
Amortization of deferred charge assets and deferred gain liabilities (4)	42,640		—		42,640		37,744		—		37,744		13,781		—		13,781
Amortization of fair value adjustments (5)	28,667		—		28,667		50,070		—		50,070		12,877		—		12,877
Changes in fair value - fair value option (6)	119,046		—		119,046		117,181		—		117,181		6,664		—		6,664
Net incurred losses and LAE	$	14,830	$	30,165	$	44,995	$	(71,934)	$	123,559	$	51,625	$	(318,518)	$	12,451	$	(306,067)

(2)Represents the gross change in our actuarial estimates of IBNR, less amounts recoverable.

(3) Represents the change in the estimate of the total future costs to administer the claims.

(4) Relates to the amortization of deferred charge assets and deferred gain liabilities on retroactive reinsurance contracts.

(5) Relates to the amortization of fair value adjustments associated with the acquisition of companies.

(6) Represents the changes in the fair value of liabilities related to our assumed retroactive reinsurance agreements for which we have elected the fair value option.

Net incurred losses and LAE in the Atrium segment for the years ended December 31, 2020, December 31, 2019 and 2018 were as follows:


	2020						2019						2018
	Prior Period		Current Period		Total		Prior Period		Current Period		Total		Prior Period		Current Period		Total
Net losses paid	$	40,196	$	33,724	$	73,920	$	43,572	$	34,617	$	78,189	$	28,969	$	35,537	$	64,506
Net change in case and LAE reserves(1)	(14,145)		21,390		7,245		(13,278)		16,812		3,534		(10,161)		16,492		6,331
Net change in IBNR reserves(2)	(31,773)		38,434		6,661		(38,380)		33,598		(4,782)		(27,507)		31,598		4,091
Increase (reduction) in estimates of net ultimate losses	(5,722)		93,548		87,826		(8,086)		85,027		76,941		(8,699)		83,627		74,928

Increase (reduction) in provisions for unallocated LAE (3)	48		(77)		(29)		—		—		—		—		—		—
Amortization of fair value adjustments (4)	(571)		—		(571)		335		—		335		(5,118)		—		(5,118)
Net incurred losses and LAE	$	(6,245)	$	93,471	$	87,226	$	(7,751)	$	85,027	$	77,276	$	(13,817)	$	83,627	$	69,810

(2)Represents the gross change in our actuarial estimates of IBNR, less amounts recoverable.

(3) Represents the change in the estimate of the total future costs to administer the claims.

(4) Relates to the amortization of fair value adjustments associated with the acquisition of companies.

Net incurred losses and LAE in the StarStone segment for the years ended December 31, 2020, December 31, 2019 and 2018 were as follows:


	2020						2019						2018
	Prior Period		Current Period		Total		Prior Period		Current Period		Total		Prior Period		Current Period		Total
Net losses paid	$	300,037	$	26,831	$	326,868	$	375,377	$	75,458	$	450,835	$	289,981	$	137,390	$	427,371
Net change in case and LAE reserves (1)	(130,502)		35,458		(95,044)		(95,183)		90,497		(4,686)		(77,821)		141,682		63,861
Net change in IBNR reserves (2)	(165,909)		183,563		17,654		(163,340)		185,361		22,021		(87,963)		134,464		46,501
Increase in estimates of net ultimate losses	3,626		245,852		249,478		116,854		351,316		468,170		124,197		413,536		537,733
Increase (reduction) in provisions for unallocated LAE (3)	(466)		17,710		17,244		(2,666)		3,568		902		(3,042)		8,655		5,613
Amortization of deferred charge assets and deferred gain liabilities (4)	606		—		606		—		—		—		—		—		—
Amortization of fair value adjustments (5)	(590)		—		(590)		168		—		168		(266)		—		(266)
Net incurred losses and LAE	$	3,176	$	263,562	$	266,738	$	114,356	$	354,884	$	469,240	$	120,889	$	422,191	$	543,080

(2) Represents the gross change in our actuarial estimates of IBNR, less amounts recoverable.

(3) Represents the change in the estimate of the total future costs to administer the claims.

(4) Relates to the amortization of deferred charge assets and deferred gain liabilities on retroactive reinsurance contracts.

(5) Relates to the amortization of fair value adjustments associated with the acquisition of companies.

Schedule of Gross and Net Losses and LAE Reserves by Category

The following table shows the components of the 2020 reduction in estimates of net ultimate losses related to prior periods by line of business for the Non-life Run-off segment.


	2020
	Net losses paid		Net change in case and LAE reserves		Net change in IBNR reserves		Increase (reduction) in estimates of net ultimate losses
Asbestos	$	132,853	$	(1,300)	$	(150,054)	$	(18,501)
Environmental	23,866		(266)		(36,362)		(12,762)
General Casualty	170,502		(68,744)		(127,421)		(25,663)
Workers' Compensation	142,790		(176,927)		(149,198)		(183,335)
Marine, aviation and transit	33,927		(14,458)		(50,558)		(31,089)
Construction defect	27,476		(6,092)		(13,382)		8,002
Professional indemnity/ Directors & Officers	63,878		3,698		(79,181)		(11,605)
Motor	349,366		(106,561)		(95,040)		147,765
Property	71,422		(24,356)		(64,331)		(17,265)
All Other	48,831		(54,604)		23,110		17,337
Total	$	1,064,911	$	(449,610)	$	(742,417)	$	(127,116)

The following table shows the components of the 2019 reduction in estimates of net ultimate losses related to prior periods by line of business for the Non-life Run-off segment.


	2019
	Net losses paid		Net change in case and LAE reserves		Net change in IBNR reserves		Increase (reduction) in estimates of net ultimate losses
Asbestos	$	118,557	$	35,003	$	(146,749)	$	6,811
Environmental	16,899		13,796		(15,707)		14,988
General Casualty	175,044		(89,968)		(91,818)		(6,742)
Workers' Compensation	208,961		(156,435)		(188,944)		(136,418)
Marine, aviation and transit	82,058		(77,958)		(24,508)		(20,408)
Construction defect	32,078		(8,313)		(25,025)		(1,260)
Professional indemnity/ Directors & Officers	103,413		(36,986)		(104,984)		(38,557)
Motor	276,563		(134,127)		(179,887)		(37,451)
Property	94,093		(73,259)		(7,358)		13,476
All Other	75,138		(25,749)		(62,913)		(13,524)
Total	$	1,182,804	$	(553,996)	$	(847,893)	$	(219,085)

The following table shows the components of the 2018 reduction in estimates of net ultimate losses related to prior periods by line of business for the Non-life Run-off segment.


	2018
	Net losses paid		Net change in case and LAE reserves		Net change in IBNR reserves		Increase (reduction) in estimates of net ultimate losses
Asbestos	$	108,248	$	(21,535)	$	(151,662)	$	(64,949)
Environmental	21,273		479		(7,599)		14,153
General Casualty	141,624		(115,240)		(60,828)		(34,444)
Workers' Compensation	139,226		(178,138)		(115,648)		(154,560)
Marine, aviation and transit	67,831		(44,200)		(21,188)		2,443
Construction defect	22,182		(7,257)		(33,146)		(18,221)
Professional indemnity/ Directors & Officers	161,797		(11,159)		(130,957)		19,681
Motor	104,182		(109,962)		(34,215)		(39,995)
Property	22,178		(24,271)		(11,497)		(13,590)
All Other	50,271		(40,841)		(6,387)		3,043
Total	$	838,812	$	(552,124)	$	(573,127)	$	(286,439)


	2020
	Gross						Net
	OLR		IBNR		Total		OLR		IBNR		Total
	(in thousands of U.S. dollars)
Asbestos	$	544,438	$	1,234,101	$	1,778,539	$	464,102	$	1,122,021	$	1,586,123
Environmental	184,783		118,111		302,894		164,709		100,339		265,048
General casualty	610,437		1,279,991		1,890,428		492,039		1,247,662		1,739,701
Workers' compensation/personal accident	1,087,324		918,238		2,005,562		912,068		776,941		1,689,009
Marine, aviation and transit	271,469		73,081		344,550		229,464		56,414		285,878
Construction defect	23,380		85,578		108,958		23,109		83,039		106,148
Professional indemnity/Directors & Officers	764,768		336,705		1,101,473		526,333		307,349		833,682
Motor	619,682		355,044		974,726		451,097		283,576		734,673
Property	116,398		35,832		152,230		97,826		34,182		132,008
Other	217,746		204,819		422,565		141,448		121,895		263,343
	$	4,440,425	$	4,641,500	$	9,081,925	$	3,502,195	$	4,133,418	$	7,635,613
Fair value adjustments					(142,854)						(128,841)
Fair value adjustments - fair value option					(54,589)						(33,163)
Net deferred charge assets and gains on retroactive reinsurance					—						(218,722)

ULAE					350,600						333,913
Total					$	9,235,082					$	7,588,800


	2019
	Gross						Net
	OLR		IBNR		Total		OLR		IBNR		Total
	(in thousands of U.S. dollars)
Asbestos	$	542,681	$	1,373,678	$	1,916,359	$	490,117	$	1,271,982	$	1,762,099
Environmental	187,165		156,121		343,286		173,878		142,351		316,229
General casualty	501,863		489,129		990,992		399,396		421,426		820,822
Workers' compensation/personal accident	1,270,530		977,808		2,248,338		963,578		751,074		1,714,652
Marine, aviation and transit	290,067		121,577		411,644		244,611		100,135		344,746
Construction defect	29,772		98,312		128,084		29,245		94,888		124,133
Professional indemnity/Directors & Officers	693,760		265,490		959,250		485,478		170,926		656,404
Motor	480,668		233,806		714,474		317,829		165,543		483,372
Property	140,620		63,604		204,224		122,010		56,450		178,460
Other	269,956		165,882		435,838		208,647		97,573		306,220
	$	4,407,082	$	3,945,407	$	8,352,489	$	3,434,789	$	3,272,348	$	6,707,137
Fair value adjustments					(170,689)						(157,036)
Fair value adjustments - fair value option					(217,933)						(129,848)
Net deferred charge assets and gain liabilities on retroactive reinsurance					—						(259,587)

ULAE					331,494						331,494
Total					$	8,295,361					$	6,492,160


	2019
	Gross						Net
	OLR		IBNR		Total		OLR		IBNR		Total
	(in thousands of U.S. dollars)
Marine, Aviation and Transit	$	24,668	$	34,156	$	58,824	$	21,012	$	24,829	$	45,841
Binding Authorities	31,507		54,039		85,546		29,590		51,984		81,574
Reinsurance	18,385		29,533		47,918		16,209		23,338		39,547
Accident and Health	5,460		7,880		13,340		4,735		7,469		12,204
Non-Marine Direct and Facultative	9,121		10,935		20,056		8,584		9,637		18,221
Total	$	89,141	$	136,543	$	225,684	$	80,130	$	117,257	$	197,387
Fair value adjustments					3,700						3,181
ULAE					2,288						2,288
Total					$	231,672					$	202,856


	2020
	Gross						Net
	OLR		IBNR		Total		OLR		IBNR		Total
	(in thousands of U.S. dollars)
Casualty	$	115,295	$	276,941	$	392,236	$	98,721	$	232,433	$	331,154
Marine	142,631		174,015		316,646		119,628		132,482		252,110
Property	322,735		117,240		439,975		141,089		81,459		222,548
Aerospace	84,515		36,178		120,693		42,100		18,240		60,340
Workers' Compensation	12,044		11,589		23,633		12,044		11,589		23,633
Total	$	677,220	$	615,963	$	1,293,183	$	413,582	$	476,203	$	889,785
Fair value adjustments					(329)						1,010
ULAE					35,102						35,101
Total					$	1,327,956					$	925,896


	2019
	Gross						Net
	OLR		IBNR		Total		OLR		IBNR		Total
	(in thousands of U.S. dollars)
Casualty	$	121,945	$	210,969	$	332,914	$	108,543	$	204,800	$	313,343
Marine	189,355		161,379		350,734		158,252		128,242		286,494
Property	341,677		131,596		473,273		150,559		87,653		238,212
Aerospace	75,764		32,325		108,089		47,256		22,389		69,645
Workers' Compensation	15,089		19,865		34,954		15,089		19,865		34,954
Total	$	743,830	$	556,134	$	1,299,964	$	479,699	$	462,949	$	942,648
Fair value adjustments					(522)						1,600
ULAE					18,852						18,852
Total					$	1,318,294					$	963,100

Incurred and Paid Loss Development Information, and IBNR Liabilities and Cumulative Loss Frequency


	Acquisition Year
	2010 and Prior		2011		2012		2013		2014		2015		2016		2017		2018		2019		2020		Total
Asbestos	$	142,028	$	—	$	—	$	7,767	$	—	$	—	$	407,958	$	726,901	$	1,105	$	277,947	$	—	$	1,563,706
Environmental	42,356		—		—		—		—		—		89,865		22,891		11,203		95,072		—		261,387
General casualty	52,582		13,270		9,983		16,696		31,610		34,704		3,727		44,551		228,419		218,995		1,077,908		1,732,445
Workers' compensation/personal accident	42,908		125,649		—		48,207		—		287,653		219,157		53,659		322,737		387,438		199,864		1,687,272
Marine, aviation and transit	8,760		2,747		—		(188)		10,592		1,616		32		77,321		106,431		56,709		19,848		283,868
Construction defect	43		—		—		—		—		36,258		14,289		18,836		—		36,709		—		106,135
Professional indemnity/Directors & Officers	7,539		9,564		23,210		—		20,942		—		76,314		—		331,676		130,906		232,934		833,085
Motor	12,452		201		276		—		1,465		13,147		—		3,710		260,797		17,899		422,321		732,268
Property	3,301		161		7,008		—		18,165		3,880		465		(114)		47,270		39,286		10,887		130,309
All Other	17,473		854		2,696		4,260		9,676		6,959		23,582		94,499		18,222		78,474		—		256,695
Total	$	329,442	$	152,446	$	43,173	$	76,742	$	92,450	$	384,217	$	835,389	$	1,042,254	$	1,327,860	$	1,339,435	$	1,963,762	$	7,587,170

Business Acquired and Contracts Incepting in the Year Ended December 31, 2011


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance																							As of December 31, 2020
			For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired		2011 (unaudited)		2012 (unaudited)		2013 (unaudited)		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	597,263	$	621,819	$	589,004	$	489,877	$	426,777	$	375,227	$	319,423	$	274,136	$	261,234	$	240,808	$	229,458	$	17,493	112,837
2011	—		102		36		45		54		61		71		79		86		93		100		—		19
2012	—				122		11		10		10		10		17		18		17		17		—		7
2013	—						23		43		15		15		15		15		15		15		—		16
2014	—								1		3		3		3		18		15		14		2		14
2015	—										—		(2)		(2)		32		24		19		—		1
2016	—												2		(139)		(111)		(99)		(88)		7		2
2017	—														—		21		15		17		1		2
2018	—																7		8		8		1		1
2019	—																		—		2		1		1
2020	—																				2		1		1
	$	597,263																			$	229,564	$	17,506	112,901

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year			2011 (unaudited)		2012 (unaudited)		2013 (unaudited)		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior			$	58,934	$	98,969	$	90,711	$	24,238	$	19,370	$	27,563	$	19,697	$	31,108	$	56,741	$	77,051
2011			27		36		46		54		61		71		79		86		93		100
2012					6		10		10		10		10		17		17		17		17
2013							6		11		15		15		15		15		15		15
2014									1		3		3		3		4		7		7
2015											(1)		(2)		(2)		2		11		18
2016													2		(153)		(125)		(114)		(105)
2017															—		3		6		10
2018																	1		4		5
2019																			—		—
2020																					—
																					$	77,118
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance																					$	152,446

Business Acquired and Contracts Incepting in the Year Ended December 31, 2012


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance																					As of December 31, 2020
			For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired		2012 (unaudited)		2013 (unaudited)		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020			IBNR		Cumulative Number of Claims
2010 and Prior	$	326,229	$	328,419	$	321,295	$	312,510	$	297,081	$	286,660	$	277,778	$	269,004	$	263,472	$	252,318		$	10,889	47,773
2011	1,487		1,466		1,336		1,182		1,095		1,072		1,049		1,032		1,032		1,032			—		5
2012	55		81		49		363		344		406		397		167		167		167			—		6
2013	—				946		119		427		433		421		136		136		136			—		5
2014	(60)						2,991		3,108		1,552		1,300		1,195		1,146		1,068			1		7
2015	—								729		1,517		739		739		739		739			—		5
2016	(485)										67		1,266		1,113		1,059		445			37		2
2017	—												75		167		100		100			—		4
2018	(59)														—		154		74			4		1
2019	(123)																274		145			11		4
2020	—																		164			—		3
	$	327,044																	$	256,388		$	10,942	47,815

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year			2012 (unaudited)		2013 (unaudited)		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior			$	3,194	$	70,440	$	112,966	$	144,553	$	169,781	$	180,270	$	194,011	$	204,482	$	209,656
2011			120		496		742		866		928		990		1,032		1,032		1,032
2012			31		49		49		52		167		167		167		167		167
2013					109		119		136		136		136		136		136		136
2014							67		224		459		675		864		989		1,053
2015									112		117		739		739		739		739
2016											3		56		98		98		98
2017													13		43		100		100
2018															—		30		34
2019																	18		36
2020																			164
																			$	213,215
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance																	$	43,173

Business Acquired and Contracts Incepting in the Year Ended December 31, 2013


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance																	As of December 31, 2020
			For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired		2013 (unaudited)		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)				2020			IBNR	Cumulative Number of Claims
2010 and Prior	$	320,974	$	349,297	$	354,585	$	361,812	$	356,522	$	340,248	$	326,851	$	313,347	$	314,497		$	16,353	56,441
2011	96,929		102,288		100,482		100,243		95,848		87,913		86,403		85,919		81,616			2,700		11,185
2012	131,119		127,323		121,364		118,085		114,772		110,045		107,853		108,025		105,564			1,831		10,423
2013	13,062		90,739		91,634		88,920		85,791		81,732		80,036		80,091		79,174			1,073		5,656
2014	—				4,514		3,714		3,425		16,800		16,225		16,304		16,269			55		174
2015	—						265		280		982		329		250		237			42		2
2016	—								103		71		70		69		69			1		1
2017	—										30		13		13		13			—		1
2018	—												22		17		18			—		1
2019	—														13		15			—		1
2020	—																61			4		1
	$	562,084															$	597,533		$	22,059	83,886

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year			2013 (unaudited)		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior			$	74,418	$	134,409	$	186,762	$	222,891	$	229,942	$	243,755	$	249,023	$	258,436
2011			30,323		52,455		63,952		70,498		75,055		77,290		79,112		73,282
2012			33,361		59,095		74,663		86,916		92,445		96,780		99,781		98,096
2013			17,022		37,653		52,638		62,876		68,866		71,487		74,556		74,472
2014					993		1,747		2,256		15,804		15,959		16,123		16,164
2015							43		102		112		165		190		191
2016									34		64		65		66		67
2017											9		13		13		13
2018													13		17		18
2019															8		15
2020																	37
																	$	520,791
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance													$	76,742

Business Acquired and Contracts Incepting in the Year Ended December 31, 2014


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance													As of December 31, 2020
			For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired		2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)						2019 (unaudited)	2020			IBNR	Cumulative Number of Claims
2010 and Prior	$	142,341	$	133,678	$	123,973	$	155,274	$	142,256	$	141,058	$	145,889	$	144,874		$	6,454	12,014
2011	74,248		129,149		154,394		134,137		136,257		137,806		139,997		135,181			10,057		6,228
2012	141,597		147,347		178,577		187,062		179,745		165,821		162,740		160,769			10,449		6,393
2013	86,920		76,313		95,125		83,564		88,189		90,387		88,391		90,951			8,947		3,173
2014	—		13,802		9,554		14,506		7,438		6,590		6,954		7,098			1,708		1,112
2015	—				33,549		15,553		20,741		18,929		17,206		17,090			72		183
2016	—						330		1,108		4,594		771		724			89		45
2017	—								5,078		3,893		8,200		8,463			24		37
2018	—										6		5		82			—		19
2019	—												—		—			—		10
2020	—														—			—		6
	$	445,106													$	565,232		$	37,800	29,220

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year			2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior			$	36,509	$	82,699	$	103,197	$	118,857	$	120,309	$	121,847	$	127,622
2011			84,031		109,675		110,575		113,701		120,155		123,335		123,364
2012			47,495		90,307		120,910		130,001		130,105		133,900		133,026
2013			21,752		40,817		48,223		56,941		65,073		65,625		66,225
2014			1,462		2,504		3,293		3,989		6,147		6,660		6,654
2015					1,741		4,308		11,566		13,371		13,417		13,473
2016							20		556		558		561		559
2017									537		1,541		1,238		1,778
2018											5		5		81
2019													—		—
2020															—
															$	472,782
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance									$	92,450

Business Acquired and Contracts Incepting in the Year Ended December 31, 2015


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance									As of December 31, 2020
			For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)						2018 (unaudited)		2019 (unaudited)	2020			IBNR	Cumulative Number of Claims
2010 and Prior	$	1,003,949	$	933,328	$	640,324	$	594,466	$	564,502	$	521,598	$	505,379		$	49,461	13,557
2011	124,727		137,429		131,303		129,657		128,155		128,672		126,764			14,306		5,587
2012	179,136		187,488		197,895		201,017		194,277		193,553		192,426			18,110		4,885
2013	229,590		189,838		196,582		199,983		189,737		185,101		184,590			13,855		4,699
2014	144,392		143,193		137,668		142,937		137,541		152,478		147,567			7,413		7,783
2015	23,750		70,276		69,322		66,152		64,974		69,465		73,256			6,959		10,997
2016	—				14,872		13,141		13,440		14,576		12,868			2,178		14,283
2017	—						4,095		4,527		5,277		6,860			345		3,534
2018	—								3,055		1,889		1,805			985		400
2019	—										1,838		1,873			1,831		51
2020	—												1,951			1,962		3
	$	1,705,544											$	1,255,339		$	117,405	65,779

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year			2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior			$	32,819	$	83,350	$	134,737	$	166,983	$	195,205	$	220,984
2011			33,827		55,115		71,023		86,397		98,000		105,178
2012			52,728		94,831		119,520		142,358		158,620		168,213
2013			46,761		89,930		120,509		145,788		159,767		164,215
2014			30,747		64,475		91,016		109,451		125,619		133,094
2015			20,653		38,709		46,668		51,994		59,963		63,181
2016					5,603		7,371		8,687		9,861		10,321
2017							2,321		3,925		4,767		5,047
2018									567		862		820
2019											45		65
2020													4
													$	871,122
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance					$	384,217

Business Acquired and Contracts Incepting in the Year Ended December 31, 2015 - Workers' Compensation


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance									As of December 31, 2020
			For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)						2018 (unaudited)		2019 (unaudited)	2020			IBNR	Cumulative Number of Claims
2010 and Prior	$	953,178	$	868,509	$	569,692	$	518,764	$	490,534	$	449,380	$	434,422		$	40,504	8,605
2011	76,789		73,723		69,009		68,013		66,781		67,741		65,825			3,685		1,241
2012	120,298		110,007		108,251		106,625		100,187		99,212		98,733			4,613		1,809
2013	146,237		124,726		122,238		121,010		113,056		112,677		113,414			5,595		2,386
2014	82,141		86,852		82,038		83,095		78,389		78,948		80,307			1,513		3,686
2015	4,089		18,647		12,623		13,488		12,295		11,309		11,337			557		2,900
2016	—				873		955		583		536		514			52		38
2017	—						358		61		41		33			13		10
2018	—								—		5		3			—		1
2019	—										1		3			1		1
2020	—												—			—		—
	$	1,382,732											$	804,591		$	56,533	20,677

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year			2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior			$	20,630	$	65,008	$	107,906	$	132,025	$	155,329	$	177,205
2011			16,032		30,462		39,635		50,470		55,595		58,420
2012			25,103		52,851		66,092		79,367		88,369		91,332
2013			27,737		55,675		75,065		91,559		100,890		104,265
2014			17,824		38,051		53,308		65,561		72,696		75,781
2015			3,034		5,672		7,917		9,169		9,248		9,461
2016					134		363		417		447		452
2017							2		10		18		19
2018									—		1		2
2019											—		1
2020													—
													$	516,938
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance					$	287,653

Business Acquired and Contracts Incepting in the Year Ended December 31, 2016


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance							As of December 31, 2020
					For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired				2016 (unaudited)						2017 (unaudited)		2018 (unaudited)		2019 (unaudited)	2020			IBNR	Cumulative Number of Claims
2010 and Prior	$	1,304,938			$	1,316,544	$	1,346,575	$	1,321,289	$	1,322,161	$	1,361,353		$	305,042	24,449
2011	17,291				17,291		19,920		19,754		18,829		18,609			2,266		861
2012	13,717				13,717		17,020		14,765		12,717		13,037			1,829		809
2013	373				373		1,312		1,237		1,120		914			603		127
2014	391				391		1,380		1,056		869		817			310		57
2015	—				—		—		—		—		—			—		—
2016	—				—		—		—		—		—			—		—
2017	—						—		—		—		—			—		—
2018	—								—		—		—			—		—
2019	—										—		—			—		—
2020	—												—			—		—
	$	1,336,710											$	1,394,730		$	310,050	26,303

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
					For the Years Ended December 31,
Accident Year					2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior					$	101,098	$	222,703	$	331,218	$	445,770	$	536,987
2011					2,758		6,647		8,218		9,691		13,098
2012					2,734		5,206		6,461		7,587		8,492
2013					145		191		278		285		301
2014					178		207		284		366		463
2015					—		—		—		—		—
2016					—		—		—		—		—
2017							—		—		—		—
2018									—		—		—
2019											—		—
2020													—
													$	559,341
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	835,389

Business Acquired and Contracts Incepting in the Year Ended December 31, 2016 - Workers' Compensation


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance							As of December 31, 2020
					For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired				2016 (unaudited)						2017 (unaudited)		2018 (unaudited)		2019 (unaudited)	2020			IBNR	Cumulative Number of Claims
2010 and Prior	$	437,457			$	437,805	$	403,319	$	391,476	$	382,446	$	367,109		$	19,015	9,452
2011	15,376				15,376		16,399		16,501		16,327		16,472			1,374		469
2012	13,074				13,074		15,465		13,276		11,379		11,256			1,020		612
2013	—				—		—		—		—		—			—		—
2014	—				—		—		—		—		—			—		—
2015	—				—		—		—		—		—			—		—
2016	—				—		—		—		—		—			—		—
2017	—						—		—		—		—			—		—
2018	—								—		—		—			—		—
2019	—										—		—			—		—
2020	—												—			—		—
	$	465,907											$	394,837		$	21,409	10,533

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
					For the Years Ended December 31,
Accident Year					2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior					$	35,518	$	65,264	$	90,599	$	127,081	$	155,433
2011					2,631		5,871		7,305		8,756		12,130
2012					2,638		5,028		6,247		7,382		8,117
2013					—		—		—		—		—
2014					—		—		—		—		—
2015					—		—		—		—		—
2016					—		—		—		—		—
2017							—		—		—		—
2018									—		—		—
2019											—		—
2020													—
													$	175,680
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	219,157

Business Acquired and Contracts Incepting in the Year Ended December 31, 2017


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired					2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	1,507,609				$	1,433,301	$	1,351,451	$	1,364,113	$	1,349,226	$	749,197	31,566
2011	40,743					29,274		25,389		27,316		26,942		5,834		8
2012	43,653					35,470		31,238		29,456		28,485		3,744		10
2013	35,671					30,338		28,139		24,707		29,829		1,860		11
2014	32,858					20,315		16,984		15,996		16,342		2,287		20
2015	8,808					6,494		7,002		6,295		6,043		234		8
2016	362					(4)		126		919		1,074		394		3
2017	—					174		—		—		—		—		1
2018	—							—		—		—		—		—
2019	—									—		—		—		—
2020	—											—		—		—
	$	1,669,704										$	1,457,941	$	763,550	31,627

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Years Ended December 31,
Accident Year						2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior						$	85,514	$	175,630	$	257,071	$	334,586
2011						4,125		9,257		12,971		15,407
2012						10,348		15,372		18,605		21,076
2013						9,509		15,714		21,280		25,832
2014						6,482		8,986		11,559		12,668
2015						1,361		3,720		4,687		5,582
2016						(56)		66		434		536
2017						4		—		—		—
2018								—		—		—
2019										—		—
2020												—
												$	415,687
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	1,042,254

Business Acquired and Contracts Incepting in the Year Ended December 31, 2018


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	662,009				$	497,101	$	476,164	$	409,505	$	50,970	223,572
2011	164,556					150,408		150,388		147,796		16,240		14,072
2012	232,116					224,955		224,959		225,528		29,903		14,382
2013	272,732					274,377		268,237		250,013		35,175		16,126
2014	419,593					462,858		439,396		415,829		38,688		19,463
2015	365,429					483,489		480,093		496,187		62,476		24,768
2016	173,309					175,428		178,061		169,872		36,090		2,026
2017	207,040					207,190		205,466		204,490		55,056		4,163
2018	315,659					315,659		285,038		282,279		53,287		4,929
2019	—							68,271		68,041		9,762		1,634
2020	—									—		—		—
	$	2,812,443								$	2,669,540	$	387,647	325,135

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior						$	50,515	$	86,132	$	81,554
2011						26,236		53,151		65,522
2012						31,772		81,356		106,297
2013						41,544		96,968		133,398
2014						90,689		188,721		235,787
2015						95,688		199,373		269,559
2016						6,854		63,982		93,705
2017						56		72,800		113,770
2018						—		139,815		191,442
2019								39,099		50,646
2020										—
										$	1,341,680
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	1,327,860

Business Acquired and Contracts Incepting in the Year Ended December 31, 2018 - General Casualty


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	130,049				$	74,102	$	70,937	$	67,933	$	4,827	47,893
2011	18,044					16,554		16,650		15,855		151		1,421
2012	37,454					33,433		29,123		29,760		3,270		1,593
2013	43,301					56,092		46,596		46,999		4,352		1,596
2014	66,562					80,896		74,947		68,535		5,802		2,291
2015	79,191					94,124		104,790		109,694		14,188		3,594
2016	28,825					28,825		36,585		36,684		10,075		253
2017	37,209					37,209		41,664		43,174		14,554		230
2018	39,888					39,888		40,753		39,157		11,605		182
2019	—							6,767		6,187		394		34
2020	—									—		—		—
	$	480,523								$	463,978	$	69,218	59,087

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior						$	9,164	$	18,817	$	29,840
2011						2,349		7,115		11,018
2012						1,281		11,453		14,383
2013						10,404		19,938		27,717
2014						13,766		27,833		41,899
2015						15,494		31,535		49,860
2016						—		14,109		18,916
2017						—		11,048		21,130
2018						—		8,879		17,455
2019								2,373		3,341
2020										—
										$	235,559
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	228,419

Business Acquired and Contracts Incepting in the Year Ended December 31, 2018 - Workers' Compensation


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	131,873				$	122,831	$	129,280	$	131,775	$	39,843	2,098
2011	29,897					28,685		29,981		27,203		9,067		401
2012	28,749					29,181		27,676		26,833		10,597		468
2013	38,029					38,554		38,093		35,212		13,243		869
2014	65,049					66,346		57,163		52,797		17,605		1,345
2015	38,851					39,379		35,235		33,253		13,026		1,464
2016	44,686					44,686		38,945		37,714		15,857		892
2017	52,360					52,360		49,156		45,529		23,004		998
2018	65,075					65,075		60,923		59,768		19,310		886
2019	—							20,889		21,417		4,445		383
2020	—									—		—		—
	$	494,569								$	471,501	$	165,997	9,804

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior						$	604	$	11,788	$	21,726
2011						2,281		5,592		9,418
2012						516		5,508		7,941
2013						1,525		7,773		12,280
2014						3,260		14,687		21,380
2015						1,403		4,355		9,844
2016						—		3,666		7,176
2017						—		5,900		9,088
2018						—		28,725		34,317
2019								13,483		15,594
2020										—
										$	148,764
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	322,737

Business Acquired and Contracts Incepting in the Year Ended December 31, 2018 - Motor


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	43,818				$	31,489	$	30,036	$	33,230	$	2,599	1,323
2011	48,231					38,092		37,707		36,301		2,031		1,239
2012	65,427					58,006		63,786		59,276		5,862		1,641
2013	78,456					71,276		65,012		55,345		5,744		683
2014	116,677					103,761		90,902		84,459		5,243		1,260
2015	135,855					133,493		132,167		132,165		15,246		1,510
2016	93,164					95,283		97,040		91,600		9,824		732
2017	100,321					100,471		99,135		102,038		16,628		2,797
2018	180,471					180,471		157,556		160,143		21,609		3,731
2019	—							39,757		39,647		4,955		1,200
2020	—									—		—		—
	$	862,420								$	794,204	$	89,741	16,116

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior						$	7,460	$	13,722	$	16,655
2011						6,060		12,980		15,464
2012						12,380		24,433		31,136
2013						11,114		29,311		35,186
2014						22,393		49,089		60,254
2015						21,712		61,928		84,976
2016						6,854		43,851		65,287
2017						56		48,661		73,440
2018						—		86,861		120,041
2019								22,687		30,968
2020										—
										$	533,407
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	260,797

Business Acquired and Contracts Incepting in the Year Ended December 31, 2018 - Professional Indemnity/Directors & Officers


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2018 (unaudited)		2019 (unaudited)		2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	236,568				$	137,394	$	147,383	$	143,585	$	(3,639)	56,674
2011	46,512					52,553		48,884		51,600		3,185		3,762
2012	57,937					70,636		69,641		74,884		4,399		3,285
2013	59,457					63,284		78,933		76,291		10,543		3,257
2014	88,173					111,193		107,411		114,621		11,523		3,619
2015	47,337					100,975		81,272		85,394		15,074		3,990
2016	—					—		—		—		—		—
2017	—					—		—		—		—		—
2018	—					—		—		—		—		—
2019	—							—		—		—		—
2020	—									—		—		—
	$	535,984								$	546,375	$	41,085	74,587

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior						$	29,359	$	54,157	$	28,528
2011						13,123		20,017		22,250
2012						16,382		23,237		33,794
2013						10,987		21,919		34,269
2014						22,734		39,601		61,024
2015						14,245		26,595		34,834
2016						—		—		—
2017						—		—		—
2018						—		—		—
2019								—		—
2020										—
										$	214,699
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	331,676

Business Acquired and Contracts Incepting in the Year Ended December 31, 2019


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2019 (unaudited)		2020			IBNR		Cumulative Number of Claims
2010 and Prior	$	652,608				$	630,171	$	628,495		$	272,910	74,742
2011	49,873					40,554		35,876			8,773		15,218
2012	73,098					54,301		49,349			12,905		12,329
2013	112,031					93,213		88,066			29,931		14,952
2014	137,324					137,478		127,704			53,814		17,624
2015	179,651					188,833		196,007			80,816		25,081
2016	253,099					295,011		260,473			118,653		32,057
2017	116,386					116,386		116,386			116,386		2
2018	162,744					162,744		162,744			162,744		2
2019	—					54,571		64,595			6,155		1,679
2020	—							27,975			5,483		1,020
	$	1,736,814						$	1,757,670		$	868,570	194,706

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2019 (unaudited)		2020
2010 and Prior						$	26,817	$	106,195
2011						4,786		8,100
2012						6,886		9,565
2013						13,540		20,906
2014						28,188		47,310
2015						33,417		63,994
2016						56,125		84,592
2017						—		—
2018						—		—
2019						25,595		55,912
2020								21,661
								$	418,235
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	1,339,435

Business Acquired and Contracts Incepting in the Year Ended December 31, 2019 - General Casualty


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2019 (unaudited)		2020			IBNR		Cumulative Number of Claims
2010 and Prior	$	12,765				$	9,788	$	9,994		$	1,620	1,424
2011	12,321					9,490		7,979			3,587		796
2012	18,107					14,471		13,786			8,214		1,165
2013	23,750					18,230		20,960			8,897		313
2014	33,767					31,181		29,341			16,377		905
2015	58,818					45,936		41,158			18,055		2,003
2016	48,606					64,159		58,061			32,692		3,134
2017	32,188					32,188		32,188			32,188		1
2018	45,010					45,010		45,010			45,010		1
2019	—					1,750		1,873			510		225
2020	—							1,118			267		411
	$	285,332						$	261,468		$	167,417	10,378

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2019 (unaudited)		2020
2010 and Prior						$	2,230	$	2,894
2011						810		1,869
2012						3,326		6,604
2013						3,499		5,813
2014						3,878		8,155
2015						4,421		5,121
2016						4,894		10,723
2017						—		—
2018						—		—
2019						—		841
2020								453
								$	42,473
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	218,995

Business Acquired and Contracts Incepting in the Year Ended December 31, 2019 - Workers' Compensation


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
										For the Year Ended December 31,
Accident Year	Total Net Reserves Acquired					2019 (unaudited)		2020			IBNR		Cumulative Number of Claims
2010 and Prior	$	5,860				$	4,420	$	4,551		$	1,938	9,869
2011	2,474					2,410		2,409			2,342		1,082
2012	6,280					6,176		6,176			6,991		1,640
2013	16,738					18,339		15,980			14,415		2,897
2014	35,023					35,426		35,556			31,501		3,410
2015	57,194					56,171		57,314			48,840		4,802
2016	87,702					85,530		84,862			70,769		4,829
2017	84,197					84,197		84,197			84,197		1
2018	117,734					117,734		117,734			117,734		1
2019	—					—		—			—		—
2020	—							2,045			—		189
	$	413,202						$	410,824		$	378,727	28,720

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Year Ended December 31,
Accident Year						2019 (unaudited)		2020
2010 and Prior						$	607	$	696
2011						22		23
2012						22		63
2013						458		572
2014						3,080		3,443
2015						3,549		6,325
2016						7,337		12,137
2017						—		—
2018						—		—
2019						—		—
2020								127
								$	23,386
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	387,438


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
								For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired					2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	256,228				$	169,601	$	91,688	47
2011	26,488					26,983		25,162		36
2012	58,128					58,241		53,749		74
2013	68,683					63,922		47,944		140
2014	100,054					102,600		83,249		201
2015	161,383					161,352		113,476		384
2016	210,661					205,305		120,481		816
2017	316,751					342,330		168,832		1,770
2018	432,590					575,706		305,471		3,108
2019	344,495					343,168		301,463		1,351
2020	166,946					168,091		144,090		1,481
	$	2,142,407				$	2,217,299	$	1,455,605	9,408

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Years Ended December 31,
Accident Year						2020
2010 and Prior						$	2,310
2011						54
2012						601
2013						4,283
2014						5,975
2015						12,253
2016						33,985
2017						73,001
2018						111,871
2019						1,509
2020						7,695
						253,537
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	1,963,762

Business Acquired and Contracts Incepting in the Year Ended December 31, 2020 - General Casualty


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
								For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired					2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	43,511				$	43,849	$	36,455	36
2011	26,434					26,928		25,133		29
2012	55,478					55,591		51,130		60
2013	60,872					56,111		41,186		122
2014	87,620					90,182		71,022		185
2015	140,583					139,947		96,032		280
2016	142,395					143,156		100,293		394
2017	142,862					137,097		112,135		439
2018	141,803					138,267		133,942		316
2019	202,521					201,174		179,284		388
2020	83,021					82,598		77,737		338
	$	1,127,100				$	1,114,900	$	924,349	2,587

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Years Ended December 31,
Accident Year						2020
2010 and Prior						$	522
2011						54
2012						601
2013						3,258
2014						5,983
2015						10,230
2016						9,125
2017						4,149
2018						400
2019						203
2020						2,467
						36,992
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	1,077,908

Business Acquired and Contracts Incepting in the Year Ended December 31, 2020 - Motor


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
								For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired					2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	—				$	—	$	—	—
2011	—					—		—		—
2012	—					—		—		—
2013	—					—		—		—
2014	—					—		—		—
2015	2,397					3,018		603		19
2016	48,505					42,420		2,779		221
2017	154,070					185,445		38,279		1,099
2018	250,028					397,413		145,623		2,204
2019	—					—		—		—
2020	—					—		—		—
	$	455,000				$	628,296	$	187,284	3,543

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Years Ended December 31,
Accident Year						2020
2010 and Prior						$	—
2011						—
2012						—
2013						—
2014						—
2015						2,012
2016						24,804
2017						68,712
2018						110,447
2019						—
2020						—
						205,975
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	422,321

Business Acquired and Contracts Incepting in the Year Ended December 31, 2020 - Professional Indemnity/Directors & Officers


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance					As of December 31, 2020
								For the Years Ended December 31,
Accident Year	Total Net Reserves Acquired					2020		IBNR		Cumulative Number of Claims
2010 and Prior	$	4,680				$	4,678	$	4,679	1
2011	44					44		44		3
2012	2,593					2,593		2,584		4
2013	7,791					7,791		6,745		6
2014	11,949					11,949		11,947		4
2015	16,120					16,120		15,769		4
2016	16,259					16,216		16,053		9
2017	17,212					17,206		16,906		41
2018	25,323					25,290		19,209		115
2019	99,460					99,350		92,944		135
2020	34,548					34,757		30,144		79
	$	235,979				$	235,994	$	217,024	401

Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
						For the Years Ended December 31,
Accident Year						2020
2010 and Prior						$	—
2011						—
2012						—
2013						1,025
2014						—
2015						6
2016						1
2017						5
2018						475
2019						410
2020						1,138
						3,060
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance			$	232,934


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance															As of December 31, 2020
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR(1)		Cumulative Number of Claims
2010 and Prior	$	100,449	$	101,217	$	101,444	$	101,801	$	102,539	$	102,317	$	102,661	$	19	4,322
2011	16,244		18,740		19,681		19,103		27,703		27,859		28,027		429		2,962
2012	39,797		33,853		30,788		28,482		33,511		36,159		37,072		3,418		3,521
2013	51,458		47,304		54,282		53,493		56,145		63,323		67,638		9,044		4,821
2014	66,094		67,141		67,461		66,559		66,585		75,513		72,097		10,495		4,863
2015			76,470		82,050		81,685		92,904		99,425		101,191		13,037		4,323
2016					92,406		95,726		111,020		135,670		128,139		25,293		3,825
2017							100,585		135,743		161,288		166,472		34,822		3,899
2018									87,781		101,381		106,014		39,329		2,929
2019											42,595		59,902		23,758		2,581
2020													98,738		72,789		1,582
											Total		$	967,951	$	232,433	39,628
(1) Total of IBNR plus expected development on reported losses.
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
			For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior	$	99,643	$	101,181	$	101,326	$	101,712	$	101,783	$	101,813	$	101,886
2011	12,394		15,941		18,354		18,760		27,385		27,401		27,426
2012	13,336		20,634		22,746		23,711		32,644		32,666		32,706
2013	16,373		22,131		35,799		38,866		42,123		48,898		52,333
2014	4,318		16,141		27,043		36,802		46,654		49,571		51,949
2015			6,439		21,503		36,971		50,598		69,948		75,875
2016					4,206		32,864		59,074		76,175		92,223
2017							7,712		41,896		87,902		114,062
2018									18,747		34,762		54,000
2019											4,721		26,235
2020													8,102
											Total		$	636,797
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance													$	331,154


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance															As of December 31, 2020
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR(1)		Cumulative Number of Claims
2010 and Prior	$	50,395	$	47,336	$	47,194	$	47,287	$	47,175	$	47,213	$	46,828	$	62	3,037
2011	29,890		28,190		27,767		27,824		28,162		27,956		28,075		229		1,966
2012	48,204		52,010		51,710		50,435		51,231		49,176		48,706		307		2,431
2013	63,442		55,981		53,783		54,790		58,209		64,399		63,323		926		2,202
2014	50,959		54,370		49,449		56,049		51,642		51,062		49,676		1,003		3,944
2015			70,492		70,160		80,196		81,864		83,646		80,438		1,612		5,606
2016					80,830		83,187		88,459		88,023		89,309		4,150		6,658
2017							125,976		158,450		166,304		162,629		7,959		8,352
2018									164,461		164,042		161,831		16,444		10,123
2019											152,423		158,919		39,463		7,015
2020													84,427		60,327		2,703
											Total		$	974,161	$	132,482	54,037
(1) Total of IBNR plus expected development on reported losses.
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior	$	44,212	$	46,360	$	46,464	$	46,470	$	46,563	$	46,682	$	46,709
2011	24,599		25,686		26,688		26,942		27,057		27,082		27,285
2012	38,570		42,787		44,681		45,498		45,951		46,178		47,452
2013	29,436		38,880		43,027		45,575		47,698		57,539		62,037
2014	11,037		25,306		33,076		37,594		43,323		44,727		44,740
2015			10,234		30,143		50,376		56,557		59,918		62,401
2016					11,669		41,875		58,438		73,778		76,534
2017							23,986		68,233		107,787		125,335
2018									40,698		103,930		129,632
2019											33,196		84,414
2020													15,512
											Total		$	722,051
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance													$	252,110


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance															As of December 31, 2020
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR(1)		Cumulative Number of Claims
2010 and Prior	$	190,649	$	188,537	$	187,286	$	187,846	$	188,778	$	189,079	$	190,667	$	13	4,485
2011	91,712		90,272		90,328		90,018		89,918		90,259		90,406		88		1,635
2012	66,137		62,119		61,243		62,177		59,201		59,463		58,247		133		1,516
2013	78,501		65,608		65,394		64,521		62,711		61,114		61,383		152		1,955
2014	59,390		44,130		43,631		44,081		41,968		41,226		40,612		794		2,125
2015			75,514		73,946		67,944		67,733		68,678		69,314		1,377		11,435
2016					83,622		91,680		92,038		91,956		94,450		1,361		14,167
2017							152,172		169,673		181,855		171,673		4,429		14,553
2018									161,507		172,640		174,137		11,123		11,891
2019											116,634		117,009		22,609		6,166
2020													71,147		39,380		1,338
											Total		$	1,139,045	$	81,459	71,266
(1) Total of IBNR plus expected development on reported losses.
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior	$	183,649	$	186,876	$	187,040	$	187,264	$	187,285	$	187,300	$	188,080
2011	87,937		89,149		89,662		89,894		89,894		89,940		90,110
2012	48,322		52,442		54,681		55,672		55,895		58,099		58,100
2013	31,000		46,556		51,431		53,548		59,756		60,916		61,060
2014	5,517		18,945		31,854		34,869		36,461		37,609		39,681
2015			8,756		25,890		52,799		61,347		62,237		62,826
2016					23,803		54,188		72,244		81,904		83,577
2017							34,961		96,151		137,569		146,340
2018									60,944		93,275		126,763
2019											19,461		52,637
2020													7,323
											Total		$	916,497
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance													$	222,548


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance															As of December 31, 2020
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR(1)		Cumulative Number of Claims
2010 and Prior	$	18,439	$	18,083	$	18,393	$	18,906	$	18,962	$	18,759	$	18,693	$	36	622
2011	58,748		57,226		57,653		58,084		59,578		58,677		58,299		96		2,179
2012	55,293		55,087		55,870		55,823		57,044		56,771		56,907		186		2,375
2013	71,930		69,976		70,255		74,733		77,222		76,774		78,673		297		2,538
2014	65,227		53,457		53,533		52,471		54,534		48,757		45,978		485		2,867
2015			64,550		67,846		70,903		71,624		69,612		69,879		1,070		2,962
2016					35,923		43,371		46,832		43,991		42,954		1,463		2,925
2017							28,816		33,623		54,980		52,590		2,193		3,381
2018									58,573		54,969		54,831		3,491		3,390
2019											45,401		45,784		5,148		2,028
2020													8,732		3,775		357
											Total		$	533,320	$	18,240	25,624
(1) Total of IBNR plus expected development on reported losses
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior	$	15,391	$	16,530	$	17,141	$	18,209	$	18,480	$	18,535	$	18,538
2011	53,785		55,133		55,817		56,394		56,954		57,482		57,483
2012	45,618		49,009		51,787		53,271		54,415		55,160		55,290
2013	50,725		59,639		63,226		68,574		72,573		73,309		73,923
2014	17,297		31,192		38,494		40,749		43,857		43,858		43,868
2015			31,417		50,844		59,342		62,522		64,811		65,630
2016					11,001		30,516		35,884		37,909		37,933
2017							9,000		26,857		44,582		46,134
2018									24,979		39,531		43,284
2019											23,294		30,210
2020													687
											Total		$	472,980
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance													$	60,340


Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance															As of December 31, 2020
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020		IBNR(1)		Cumulative Number of Claims
2010 and Prior	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—	—
2011	—		—		—		—		—		—		—		—		—
2012	—		—		—		—		—		—		—		—		—
2013	—		—		—		—		1		1		1		—		—
2014	10,145		11,179		11,889		10,180		9,867		9,666		9,372		500		137
2015			35,735		36,078		32,567		30,742		29,757		28,768		1,870		259
2016					40,912		35,179		37,703		38,739		36,293		2,847		277
2017							28,188		29,931		22,900		23,320		3,888		295
2018									15,100		14,814		14,490		2,484		161
2019											—		—		—		—
2020													—		—		—
											Total		$	112,244	$	11,589	1,129
(1) Total of IBNR plus expected development on reported losses.
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance
	For The Years Ended December 31,
Accident Year	2014 (unaudited)		2015 (unaudited)		2016 (unaudited)		2017 (unaudited)		2018 (unaudited)		2019 (unaudited)		2020
2010 and Prior	$	—	$	—	$	—	$	—	$	—	$	—	$	—
2011	—		—		—		—		—		—		—
2012	—		—		—		—		—		—		—
2013	—		—		—		—		1		1		1
2014	969,000		3,951		6,031		7,430		7,957		8,201		8,503
2015			4,135		13,126		19,785		22,952		24,301		25,032
2016					5,170		15,229		22,940		27,632		29,539
2017							3,560		10,436		14,600		16,520
2018									2,574		6,431		9,016
2019											—		—
2020													—
											Total		$	88,611
Total outstanding liabilities for unpaid losses and LAE, net of reinsurance													$	23,633

Short-duration Insurance Contracts, Reconciliation Of Net Loss Reserves Prior To Provision For Bad Debt


	2020
	Total Net Reserves per all Acquisition Years		Provision for Bad Debt		Total Net Reserves
Asbestos	$	1,563,706	$	22,417	$	1,586,123
Environmental	261,387		3,661		265,048
General casualty	1,732,445		7,256		1,739,701
Workers' compensation/personal accident	1,687,272		1,737		1,689,009
Marine, aviation and transit	283,868		2,010		285,878
Construction defect	106,135		13		106,148
Professional indemnity/Directors & Officers	833,085		597		833,682
Motor	732,268		2,405		734,673
Property	130,309		1,699		132,008
All Other	256,695		6,648		263,343
Total	$	7,587,170	$	48,443	$	7,635,613

Reconciliation of Incurred and Paid Loss Development to Liability for Unpaid Losses and LAE

The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below:


	2020
Liabilities for unpaid losses and allocated LAE, net of reinsurance	$	331,154
Reinsurance recoverable on unpaid losses	61,082
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$	392,236

The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below:


	2020
Liabilities for unpaid losses and allocated LAE, net of reinsurance	$	252,110
Reinsurance recoverable on unpaid losses	64,536
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$	316,646

The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below:


	2020
Liabilities for unpaid losses and allocated LAE, net of reinsurance	$	222,548
Reinsurance recoverable on unpaid losses	217,427
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$	439,975

The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below:


	2020
Liabilities for unpaid losses and allocated LAE, net of reinsurance	$	60,340
Reinsurance recoverable on unpaid losses	60,353
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$	120,693

The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below:


	2020
Liabilities for unpaid losses and allocated LAE, net of reinsurance	$	23,633
Reinsurance recoverable on unpaid losses	—
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$	23,633

Average Annual Duration of Claims


	Annual Percentage Payout of Incurred Losses since Year of Acquisition, Net of Reinsurance
Year of Acquisition	Year 1		Year 2		Year 3		Year 4		Year 5		Year 6		Year 7		Year 8		Year 9		Year 10


2011 - All lines of business	25.68	%	17.45	%	(3.59)	%	(28.95)	%	(2.12)	%	3.57	%	(3.49)	%	4.99	%	11.18	%	8.86	%
2012 - All lines of business	1.30	%	26.42	%	16.71	%	12.48	%	10.00	%	4.47	%	5.48	%	4.17	%	2.12	%
2013 - All lines of business	25.96	%	21.67	%	15.93	%	11.01	%	6.15	%	3.89	%	2.24	%	0.32	%
2014 - All lines of business	33.84	%	24.15	%	11.11	%	8.07	%	3.74	%	1.65	%	1.10	%
2015 - All lines of business	17.33	%	17.09	%	12.84	%	9.80	%	7.69	%	4.65	%
2015 - Workers' compensation	13.72	%	17.09	%	12.73	%	9.73	%	6.71	%	4.27	%
2016 - All lines of business	7.67	%	9.18	%	7.99	%	8.41	%	6.86	%
2016 - Workers' Compensation	10.33	%	8.96	%	7.09	%	9.89	%	8.22	%
2017 - All lines of business	8.04	%	7.64	%	6.71	%	6.11	%

2018 - All lines of business	12.86	%	25.40	%	12.00	%
2018 - General Casualty	11.31	%	21.69	%	17.77	%
2018 - Workers' Compensation	2.03	%	19.49	%	10.03	%

2018 - Professional Indemnity/Directors & Officers	19.55	%	14.40	%	5.34	%
2018 - Motor	11.08	%	38.47	%	17.61	%
2019 - All lines of business	11.11	%	12.68	%
2019 - General Casualty	8.82	%	7.43	%
2019 - Workers' Compensation	3.67	%	2.02	%
2020 - All lines of business	11.43	%

2020 - General Casualty	3.32	%
2020 - Motor	32.78	%
2020 - Professional Indemnity/Directors & Officers	1.30	%

The following is unaudited supplementary information for average annual historical duration of claims:


	Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance
	Year 1		Year 2		Year 3		Year 4		Year 5		Year 6		Year 7		Year 8		Year 9		Year 10
Casualty	7.72	%	20.87	%	17.53	%	15.99	%	9.96	%	4.35	%	7.85	%	9.00	%	0.06	%	0.08	%

The following is unaudited supplementary information for average annual historical duration of claims:


	Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance
	Year 1		Year 2		Year 3		Year 4		Year 5		Year 6		Year 7		Year 8		Year 9		Year 10
Marine	18.17	%	30.97	%	19.08	%	9.99	%	5.02	%	2.46	%	3.48	%	2.04	%	0.99	%	0.39	%

The following is unaudited supplementary information for average annual historical duration of claims:


	Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance
	Year 1		Year 2		Year 3		Year 4		Year 5		Year 6		Year 7		Year 8		Year 9		Year 10
Property	19.10	%	28.75	%	26.40	%	8.35	%	2.47	%	2.69	%	1.55	%	1.01	%	0.02	%	0.30	%

The following is unaudited supplementary information for average annual historical duration of claims:


	Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance
	Year 1		Year 2		Year 3		Year 4		Year 5		Year 6		Year 7		Year 8		Year 9		Year 10
Aerospace	32.80	%	29.84	%	15.40	%	4.61	%	4.31	%	2.22	%	1.93	%	1.12	%	0.48	%	0.01	%

The following is unaudited supplementary information for average annual historical duration of claims:


	Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance
	Year 1		Year 2		Year 3		Year 4		Year 5		Year 6		Year 7		Year 8		Year 9		Year 10
Workers' compensation	14.40	%	29.38	%	20.46	%	11.77	%	5.19	%	2.57	%	1.61	%	—	%	—	%	—	%

Defendant Asbestos and Environmental Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Liability for Asbestos and Environmental Claims [Abstract]

Schedule Of Liability For Asbestos And Liability Claims


	2020		2019
Defendant asbestos and environmental liabilities:
Defendant asbestos liabilities	$	913,276	$	1,100,593
Defendant environmental liabilities	12,572		10,279
Estimated future expenses	42,510		51,637
Fair value adjustments	(262,029)		(314,824)
Defendant asbestos and environmental liabilities	706,329		847,685

Insurance balances recoverable:
Insurance recoveries related to defendant asbestos liabilities (net of allowance: 2020 - $4,824)	310,602		549,593
Fair value adjustments	(60,950)		(100,738)
Insurance balances recoverable	249,652		448,855

Net liabilities relating to defendant asbestos and environmental exposures	$	456,677	$	398,830

Reconciliation of Asbestos and Environmental Liabilities

The table below provides a consolidated reconciliation of the beginning and ending liability for defendant asbestos and environmental exposures for the years ended December 31, 2020, 2019 and 2018:


	2020	2019	2018
Balance as of January 1	847,685	203,320	219,164
Less: Insurance balances recoverable	448,855	135,808	122,326
Plus: Cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible insurance balances (1)	3,167	—	—
Net balance as of January 1	401,997	67,512	96,838
Total net recoveries (paid claims)	153,964	(10,434)	(6,351)
Amounts recorded in other income (expense):
Change in estimate of net ultimate liabilities	(103,166)	(4,263)	(23,221)
Reduction in estimated future expenses	(9,126)	(3,274)	—
Amortization of fair value adjustments	13,008	13,500	246
Total other expense (income)	(99,284)	5,963	(22,975)
Acquired on purchase of subsidiaries	—	335,789	—
Net balance as of December 31	456,677	398,830	67,512
Plus: Insurance balances recoverable (2)	249,652	448,855	135,808
Balance as of December 31	706,329	847,685	203,320

(1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 1 - "Significant Accounting Policies" for further details.

(2) Net of allowance for estimated uncollectible insurance balances.

Reconciliation of Allowance for Estimated Uncollectible Insurance Balances


	2020		2019
Allowance for estimated uncollectible insurance balances, beginning of year	$	3,818	$	—
Cumulative effect of change in accounting principle	3,167		—
Current period change in the allowance	(2,161)		3,818


Allowance for estimated uncollectible insurance balances, end of year	$	4,824	$	3,818

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Categorized Investments Recorded at Fair Value among Levels

We have categorized our assets and liabilities that are recorded at fair value on a recurring basis among levels based on the observability of inputs, or at fair value using NAV per share (or its equivalent) as follows:


	December 31, 2020
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value Based on NAV as Practical Expedient		Total Fair Value
Investments:
Short-term and Fixed maturity investments:
U.S. government and agency	$	—	$	951,048	$	—	$	—	$	951,048
U.K. government	—		51,082		—		—		51,082
Other government	—		502,153		—		—		502,153
Corporate	—		5,686,732		—		—		5,686,732
Municipal	—		162,669		—		—		162,669
Residential mortgage-backed	—		553,945		—		—		553,945
Commercial mortgage-backed	—		854,090		—		—		854,090
Asset-backed	—		557,460		—		—		557,460

	$	—	$	9,319,179	$	—	$	—	$	9,319,179

Other assets included within funds held - directly managed	—		14,627		—		—		14,627

Equities:
Publicly traded equity investments	$	229,167	$	31,600	$	—	$	—	$	260,767
Exchange-traded funds	311,287		—		—		—		311,287
Privately held equity investments	—		—		274,741		—		274,741
	$	540,454	$	31,600	$	274,741	$	—	$	846,795

Other investments:

Hedge funds	$	—	$	—	$	—	$	2,638,339	$	2,638,339
Fixed income funds	—		285,837		—		266,704		552,541
Equity funds	—		5,073		—		185,694		190,767
Private equity funds	—		—		—		363,103		363,103

CLO equities	—		128,083		—		—		128,083
CLO equity funds	—		—		—		166,523		166,523
Private credit funds	—		—		9,250		183,069		192,319


Other	—		—		314		12,045		12,359
	$	—	$	418,993	$	9,564	$	3,815,477	$	4,244,034
Total Investments	$	540,454	$	9,784,399	$	284,305	$	3,815,477	$	14,424,635

Cash and cash equivalents	$	385,790	$	208,272	$	—	$	—	$	594,062

Reinsurance balances recoverable on paid and unpaid losses:	$	—	$	—	$	520,830	$	—	$	520,830

Other Assets:
Derivatives qualifying as hedging	$	—	$	1,169	$	—	$	—	$	1,169
Derivatives not qualifying as hedges	—		2,964		—		—		2,964
Derivative instruments	$	—	$	4,133	$	—	$	—	$	4,133

Losses and LAE:	$	—	$	—	$	2,452,920	$	—	$	2,452,920

Other Liabilities:
Derivatives qualifying as hedging	$	—	$	28,947	$	—	$	—	$	28,947
Derivatives not qualifying as hedges	—		5,195		—		—		5,195
Derivative instruments	$	—	$	34,142	$	—	$	—	$	34,142


	December 31, 2019
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Fair Value Based on NAV as Practical Expedient		Total Fair Value
Investments:
Short-term and Fixed maturity investments:
U.S. government and agency	$	—	$	696,077	$	—	$	—	$	696,077
U.K government	—		161,772		—		—		161,772
Other government	—		702,856		—		—		702,856
Corporate	—		5,448,270		—		—		5,448,270
Municipal	—		140,687		—		—		140,687
Residential mortgage-backed	—		400,914		—		—		400,914
Commercial mortgage-backed	—		813,746		—		—		813,746
Asset-backed	—		670,235		—		—		670,235
	$	—	$	9,034,557	$	—	$	—	$	9,034,557

Other assets included within funds held - directly managed	$	—	$	14,207	$	—	$	—	$	14,207

Equities:
Publicly traded equity investments	$	297,310	$	30,565	$	—	$	—	$	327,875
Exchange-traded funds	133,047		—		—		—		133,047
Privately held equity investments	—		—		265,799		—		265,799
	$	430,357	$	30,565	$	265,799	$	—	$	726,721

Other investments:
Hedge funds	$	—	$	—	$	—	$	1,121,904	$	1,121,904
Fixed income funds	—		398,143		—		82,896		481,039
Equity funds	—		111,040		—		299,109		410,149
Private equity funds	—		—		—		323,496		323,496
CLO equities	—		—		87,555		—		87,555
CLO equity funds	—		—		—		87,509		87,509

Other	—		34		314		6,031		6,379
	$	—	$	509,217	$	87,869	$	1,920,945	$	2,518,031
Total Investments	$	430,357	$	9,588,546	$	353,668	$	1,920,945	$	12,293,516

Cash and cash equivalents	$	144,984	$	222,191	$	—	$	—	$	367,175

Reinsurance balances recoverable on paid and unpaid losses:	$	—	$	—	$	695,518	$	—	$	695,518

Other Assets:
Derivatives qualifying as hedging	$	—	$	642	$	—	$	—	$	642
Derivatives not qualifying as hedges	—		1,369		—		—		1,369
Derivative instruments	$	—	$	2,011	$	—	$	—	$	2,011

Losses and LAE:	$	—	$	—	$	2,621,122	$	—	$	2,621,122

Other Liabilities:
Derivatives qualifying as hedging	$	—	$	11,452	$	—	$	—	$	11,452
Derivatives not qualifying as hedges	—		4,106		—		—		4,106
Derivative instruments	$	—	$	15,558	$	—	$	—	$	15,558

Reconciliation of Beginning and Ending Balances for All Investments Measured at Fair Value on Recurring Basis


				2020
	Privately-held Equities	Other Investments	Total

Beginning fair value				$	265,799	$	87,869	$	353,668
Purchases				20,125		47,092		67,217
Sales				—		(1,289)		(1,289)
Total realized and unrealized losses				(11,183)		(40,368)		(51,551)

Transfer out of Level 3 into Level 2				—		(83,740)		(83,740)
Ending fair value				$	274,741	$	9,564	$	284,305


	2019
	Fixed maturity investments								Privately-held Equities		Other Investments		Total
	Corporate		Residential mortgage-backed		Commercial mortgage-backed		Asset-backed
Beginning fair value	$	37,386	$	—	$	7,389	$	9,121	$	228,710	$	39,367	$	321,973
Purchases	184		—		—		—		30,713		56,908		87,805
Sales	(3,520)		—		(784)		(3,605)		(2,016)		(590)		(10,515)
Total realized and unrealized gains (losses)	90		(1)		64		255		8,392		(7,816)		984
Transfer into Level 3 from Level 2	3,535		102		1,515		21,024		—		—		26,176
Transfer out of Level 3 into Level 2	(37,675)		(101)		(8,184)		(26,795)		—		—		(72,755)
Ending fair value	$	—	$	—	$	—	$	—	$	265,799	$	87,869	$	353,668


	2020						2019
	Liability for losses and LAE		Reinsurance balances recoverable on paid and unpaid losses		Net		Liability for losses and LAE		Reinsurance balances recoverable on paid and unpaid losses		Net
Beginning fair value	$	2,621,122	$	695,518	$	1,925,604	$	2,874,055	$	739,591	$	2,134,464
Assumed business	1,526		(180,972)		182,498		9,218		—		9,218
Incurred losses and LAE:
Reduction in estimates of ultimate losses	(73,596)		59,478		(133,074)		(32,690)		(2,958)		(29,732)
Reduction in unallocated LAE	(17,484)		—		(17,484)		(19,915)		—		(19,915)
Change in fair value	157,965		38,919		119,046		160,630		43,449		117,181
Total incurred losses and LAE	66,885		98,397		(31,512)		108,025		40,491		67,534
Paid losses	(300,234)		(101,326)		(198,908)		(416,770)		(92,145)		(324,625)
Effect of exchange rate movements	63,621		9,213		54,408		46,594		7,581		39,013
Ending fair value	$	2,452,920	$	520,830	$	1,932,090	$	2,621,122	$	695,518	$	1,925,604

The following table presents the components of the net change in fair value for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Changes in fair value due to changes in:
Duration	$	20,861	$	22,719	$	74,011
Corporate bond yield	96,478		94,462		(71,031)

Weighted cost of capital	(5,048)		—
Risk cost of capital	6,755		—		3,684
Change in fair value	$	119,046	$	117,181	$	6,664

Valuation Techniques and Inputs


		Quantitative Information about Level 3 Fair Value Measurements
		Fair Value as of December 31, 2020			Valuation Techniques		Unobservable Input	Average (1)
		(in millions of U.S. dollars)


		$	230.3		Guideline company methodology		Distribution waterfall	12.98
$	54.0			Cost as approximation of fair value		Cost as approximation of fair value
$	284.3

(1) The average represents the arithmetic average of the inputs and is not weighted by the relative fair value.

Reconciliation of Beginning and Ending Balances for All Investments Measured at Fair Value on Recurring Basis


	2020						2019
	Liability for losses and LAE		Reinsurance balances recoverable on paid and unpaid losses		Net		Liability for losses and LAE		Reinsurance balances recoverable on paid and unpaid losses		Net
Beginning fair value	$	2,621,122	$	695,518	$	1,925,604	$	2,874,055	$	739,591	$	2,134,464
Assumed business	1,526		(180,972)		182,498		9,218		—		9,218
Incurred losses and LAE:
Reduction in estimates of ultimate losses	(73,596)		59,478		(133,074)		(32,690)		(2,958)		(29,732)
Reduction in unallocated LAE	(17,484)		—		(17,484)		(19,915)		—		(19,915)
Change in fair value	157,965		38,919		119,046		160,630		43,449		117,181
Total incurred losses and LAE	66,885		98,397		(31,512)		108,025		40,491		67,534
Paid losses	(300,234)		(101,326)		(198,908)		(416,770)		(92,145)		(324,625)
Effect of exchange rate movements	63,621		9,213		54,408		46,594		7,581		39,013
Ending fair value	$	2,452,920	$	520,830	$	1,932,090	$	2,621,122	$	695,518	$	1,925,604

The following table presents the components of the net change in fair value for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Changes in fair value due to changes in:
Duration	$	20,861	$	22,719	$	74,011
Corporate bond yield	96,478		94,462		(71,031)

Weighted cost of capital	(5,048)		—
Risk cost of capital	6,755		—		3,684
Change in fair value	$	119,046	$	117,181	$	6,664

Quantitative Information

2020

2019

Valuation Technique

Unobservable (U) and Observable (O) Inputs

Weighted Average

Internal model

Corporate bond yield (O)

A rated

Internal model

Credit spread for non-performance risk (U)

0.2%

Internal model

Risk cost of capital (U)

5.1%

Internal model

Weighted average cost of capital (U)

8.25%

8.5%

Internal model

Duration - liability (U)

8.17 years

7.82 years

Internal model

Duration - reinsurance balances recoverable on paid and unpaid losses (U)

8.23 years

8.68 years

Premiums Written and Earned (Tables)

12 Months Ended

Dec. 31, 2020

Schedule of Net Premiums Written and Earned

The following tables provide the total reinsurance balances recoverable on paid and unpaid losses.


	December 31, 2020
	Non-life Run-off		StarStone		Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	938,231	$	263,638	$	1,201,869
IBNR	508,082		139,761		647,843
ULAE	16,688		—		16,688
Fair value adjustments - acquired companies	(14,014)		(1,339)		(15,353)
Fair value adjustments - fair value option	(21,427)		—		(21,427)
Total reinsurance reserves recoverable	1,427,560		402,060		1,829,620
Paid losses recoverable	172,309		87,234		259,543
Total	$	1,599,869	$	489,294	$	2,089,163

Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable on paid and unpaid losses	$	1,079,039	$	489,294	$	1,568,333
Reinsurance balances recoverable on paid and unpaid losses - fair value option	520,830		—		520,830
Total	$	1,599,869	$	489,294	$	2,089,163


	December 31, 2019
	Non-life Run-off		Atrium		StarStone		Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	972,293	$	9,011	$	264,131	$	1,245,435
IBNR	673,059		19,286		93,185		785,530

Fair value adjustments - acquired companies	(13,652)		519		(2,122)		(15,255)
Fair value adjustments - fair value option	(88,086)		—		—		(88,086)
Total reinsurance reserves recoverable	1,543,614		28,816		355,194		1,927,624
Paid losses recoverable	181,375		1,541		70,594		253,510
Total	$	1,724,989	$	30,357	$	425,788	$	2,181,134

Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable on paid and unpaid losses	$	1,029,471	$	30,357	$	425,788	$	1,485,616
Reinsurance balances recoverable on paid and unpaid losses - fair value option	695,518		—		—		695,518
Total	$	1,724,989	$	30,357	$	425,788	$	2,181,134


	December 31, 2020
	Gross		Allowance for estimated uncollectible reinsurance		Net		Provisions as a % of Gross
Reinsurers rated A- or above	$	1,464,529	$	60,801	$	1,403,728	4.2	%
Reinsurers rated below A-, secured	608,999		—		608,999		—	%
Reinsurers rated below A-, unsecured	152,757		76,321		76,436		50.0	%
Total	$	2,226,285	$	137,122	$	2,089,163	6.2	%


	December 31, 2019
	Gross		Allowance for estimated uncollectible reinsurance		Net		Provisions as a % of Gross
Reinsurers rated A- or above	$	1,731,270	$	43,427	$	1,687,843	2.5	%
Reinsurers rated below A-, secured	463,840		—		463,840		—	%
Reinsurers rated below A-, unsecured	133,663		104,212		29,451		78.0	%
Total	$	2,328,773	$	147,639	$	2,181,134	6.3	%

The following tables provide a summary of net premiums written and earned for the years ended December 31, 2020, 2019 and 2018:


	2020				2019				2018
	Premiums Written		Premiums Earned		Premiums Written		Premiums Earned		Premiums Written		Premiums Earned
Non-life Run-off
Gross	$	5,191	$	71,522	$	(25,069)	$	197,009	$	(8,910)	$	25,230
Ceded	(2,204)		(12,827)		(269)		(28,513)		(307)		(15,803)
Net	$	2,987	$	58,695	$	(25,338)	$	168,496	$	(9,217)	$	9,427
Atrium
Gross	$	206,656	$	197,492	$	192,373	$	182,678	$	171,494	$	164,428
Ceded	(23,462)		(22,099)		(20,017)		(18,619)		(18,006)		(18,113)
Net	$	183,194	$	175,393	$	172,356	$	164,059	$	153,488	$	146,315
StarStone
Gross	$	326,695	$	441,015	$	472,815	$	549,299	$	622,570	$	647,218
Ceded	(93,493)		(122,900)		(93,292)		(98,187)		(144,561)		(132,055)
Net	$	233,202	$	318,115	$	379,523	$	451,112	$	478,009	$	515,163
Other
Gross	$	13,441	$	19,889	$	18,534	$	20,544	$	32,378	$	25,237
Ceded	—		—		(22)		(164)		(311)		(363)
Net	$	13,441	$	19,889	$	18,512	$	20,380	$	32,067	$	24,874
Total
Gross	$	551,983	$	729,918	$	658,653	$	949,530	$	817,532	$	862,113
Ceded	(119,159)		(157,826)		(113,600)		(145,483)		(163,185)		(166,334)
Net	$	432,824	$	572,092	$	545,053	$	804,047	$	654,347	$	695,779

Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill and Intangible Assets


	Goodwill		Intangible assets with a definite life		Intangible assets with an indefinite life		Total
Balance as of December 31, 2018	$	109,807	$	16,887	$	67,131	$	193,825

Amortization	—		(2,257)		—		(2,257)
Balance as of December 31, 2019	$	109,807	$	14,630	$	67,131	$	191,568

Amortization	—		(1,524)		—		(1,524)
Impairment losses (StarStone International) (1)	(8,000)		—		(4,000)		(12,000)
Reclassification to assets held-for-sale (Atrium) (2)	(38,848)		(13,106)		(63,131)		(115,085)
Balance as of December 31, 2020	$	62,959	$	—	$	—	$	62,959

The gross carrying value, accumulated amortization and net carrying value of goodwill and intangible assets by segment and by type as of December 31, 2020 and 2019 was as follows:


	December 31, 2020						December 31, 2019
	Gross carrying value		Accumulated amortization		Net carrying value		Gross carrying value		Accumulated amortization		Net carrying value
Non-life Run-off segment:
Goodwill	$	62,959	$	—	$	62,959	$	62,959	$	—	$	62,959

Atrium segment:
Goodwill	—		—		—		38,848		—		38,848
Intangible assets with a definite life:
Distribution channel	—		—		—		20,000		(8,111)		11,889
Brand	—		—		—		7,000		(4,259)		2,741
Intangible assets with an indefinite life:
Lloyd’s syndicate capacity	—		—		—		33,031		—		33,031
Management contract	—		—		—		30,100		—		30,100
Total Atrium segment goodwill and intangible assets	—		—		—		128,979		(12,370)		116,609

StarStone segment:
Goodwill	—		—		—		8,000		—		8,000
Intangible assets with an indefinite life:
Lloyd’s syndicate capacity	—		—		—		4,000		—		4,000
Total StarStone segment goodwill and intangible assets	—		—		—		12,000		—		12,000
Total goodwill and intangible assets	$	62,959	$	—	$	62,959	$	203,938	$	(12,370)	$	191,568

Debt Obligations and Credit Facilities (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Amounts of Loans Payable Outstanding, and Accrued Interest

Our debt obligations were as follows:


Facility	Origination Date	Term	December 31, 2020		December 31, 2019
4.50% Senior Notes due 2022	March 10, 2017	5 years	$	349,253	$	348,616
4.95% Senior Notes due 2029	May 28, 2019	10 years	494,194		493,600
Total Senior Notes			843,447		842,216
5.75% Junior Subordinated Notes due 2040	August 26, 2020	20 years	344,812		—
EGL Revolving Credit Facility	August 16, 2018	5 years	185,000		—
2018 EGL Term Loan Facility	December 27, 2018	3 years	—		348,991
Total debt obligations			$	1,373,259	$	1,191,207

In 2020,

Interest Income and Interest Expense Disclosure

The table below provides a summary of the total interest expense for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Interest expense on debt obligations	$	57,974	$	51,245	$	25,205
Amortization of debt issuance costs	1,331		953		537


Funds withheld balances and other	3		343		(46)
Total interest expense	$	59,308	$	52,541	$	25,696

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

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Carrying Amount of Equity Attributable to Noncontrolling Interest

Noncontrolling Interest (Tables)

12 Months Ended

Dec. 31, 2020

Noncontrolling Interest [Abstract]

The following is a reconciliation of the beginning and ending carrying amount of the equity attributable to the RNCI for the years ended December 31, 2020 and 2019:


	2020		2019
Balance at beginning of year	$	438,791	$	458,543
Capital contributions	—		13,127
Dividends paid	—		(11,556)
Net losses attributable to RNCI	(27,512)		(12,029)
Change in unrealized gains (losses) on AFS investments attributable to RNCI	1,517		(126)
Change in currency translation adjustments attributable to RNCI	(1,397)		10

Change in redemption value of RNCI	(46,224)		(9,178)
Cumulative effect of change in accounting principle attributable to RNCI (1)	261		—
Balance at end of year	$	365,436	$	438,791

(1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details.

Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss)

The following table presents a roll forward of accumulated other comprehensive income (loss):


	Unrealized gains (losses) arising during the year		Cumulative Currency Translation Adjustment		Defined Benefit Pension Liability		Total
Balance, December 31, 2017, net of tax	$	2,440	$	11,171	$	(3,143)	$	10,468
Unrealized gains (losses) on fixed income available-for-sale investments arising during the year	(2,284)		—		—		(2,284)
Reclassification adjustment for net realized (gains) losses included in net earnings	63		—		—		63
Change in currency translation adjustment	—		(202)		—		(202)
Decrease in defined benefit pension liability	—		—		2,156		2,156
Total other comprehensive income (loss)	(2,221)		(202)		2,156		(267)
Other comprehensive (income) loss attributable to RNCI	222		17		—		239
Balance, December 31, 2018, net of tax	441		10,986		(987)		10,440
Unrealized gains (losses) on fixed income available-for-sale investments arising during the year	2,896		—		—		2,896
Reclassification adjustment for net realized (gains) losses included in net earnings	(3,894)		—		—		(3,894)
Change in currency translation adjustment	—		(2,428)		—		(2,428)
Decrease in defined benefit pension liability	—		—		42		42
Total other comprehensive income (loss)	(998)		(2,428)		42		(3,384)
Other comprehensive (income) loss attributable to RNCI	125		(10)		—		115
Balance, December 31, 2019, net of tax	(432)		8,548		(945)		7,171
Unrealized gains (losses) on fixed income available-for-sale investments arising during the year	104,924		—		—		104,924
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(509)		—		—		(509)
Reclassification adjustment for net realized (gains) losses included in net earnings	(18,033)		—		—		(18,033)
Reclassification to earnings on disposal of subsidiary	(11,856)		34		—		(11,822)
Change in currency translation adjustment	—		(2,103)		—		(2,103)
Decrease in defined benefit pension liability	—		—		1,152		1,152
Total other comprehensive income (loss)	74,526		(2,069)		1,152		73,609
Other comprehensive (income) loss attributable to RNCI	(1,518)		1,397		—		(121)
Balance, December 31, 2020, net of tax	$	72,576	$	7,876	$	207	$	80,659

The following table presents details about the tax effects allocated to each component of other comprehensive income (loss):


	Before Tax Amount		Tax (Expense) Benefit		Net of Tax Amount
Twelve months ended December 31, 2020
Unrealized gains (losses) on fixed income available-for-sale investments arising during the year	$	115,610	$	(10,686)	$	104,924
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(499)		(10)		(509)
Reclassification adjustment for net realized (gains) losses included in net earnings	(19,766)		1,733		(18,033)
Reclassification to earnings on disposal of subsidiary	(15,008)		3,152		(11,856)
Change in currency translation adjustment	(2,294)		191		(2,103)
Reclassification to earnings on disposal of subsidiary	34		—		34
Decrease in defined benefit pension liability	1,097		55		1,152
Other comprehensive income (loss)	$	79,174	$	(5,565)	$	73,609

The following table presents details amounts reclassified from accumulated other comprehensive income:


Details about AOCI components	2020	2019	2018	Affected Line Item in Statement where Net Earnings are presented
Unrealized gains (losses) on fixed income available-for-sale investments	18,682	3,894	(63)	Net realized and unrealized gains (losses)
	16,591	—	—	Net earnings from discontinued operations
	35,273	3,894	(63)	Total before tax
	(4,875)	—	—	Income tax (expense)
	30,398	3,894	(63)	Net of tax
Currency translation adjustment on disposal of subsidiary	(34)	—	—	Net earnings from discontinued operations
Total reclassifications for the period, net of tax	30,364	3,894	(63)

Schedule of Reclassification from Accumulated Other Comprehensive Income


	2020		2019		2018






Included within continuing operations:
Gross realized gains on fixed maturity securities, AFS	$	26,313	$	4,844	$	27
Gross realized losses on fixed maturity securities, AFS	(7,801)		(905)		(90)
Tax effect	(1,623)		—		—
Included within discontinued operations:
Gross realized gains on fixed maturity securities, AFS	1,374		12		—
Gross realized losses on fixed maturity securities, AFS	(120)		(57)		—
Tax effect	(110)		—		—
Total reclassification adjustment for net realized gains (losses) included in net earnings	$	18,033	$	3,894	$	(63)
Included within continuing operations:
Credit recoveries (losses) on fixed maturity securities, AFS	$	170	$	—	$	—
Tax effect	3		—		—
Included within discontinued operations:
Credit recoveries (losses) on fixed maturity securities, AFS	329		—		—
Tax effect	7		—		—
Total reclassification adjustment for change in allowance for credit losses recognized in net earnings	$	509	$	—	$	—

The following table presents details amounts reclassified from accumulated other comprehensive income:


Details about AOCI components	2020	2019	2018	Affected Line Item in Statement where Net Earnings are presented
Unrealized gains (losses) on fixed income available-for-sale investments	18,682	3,894	(63)	Net realized and unrealized gains (losses)
	16,591	—	—	Net earnings from discontinued operations
	35,273	3,894	(63)	Total before tax
	(4,875)	—	—	Income tax (expense)
	30,398	3,894	(63)	Net of tax
Currency translation adjustment on disposal of subsidiary	(34)	—	—	Net earnings from discontinued operations
Total reclassifications for the period, net of tax	30,364	3,894	(63)

Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Comparison of Basic and Diluted Earnings per Share

The following table sets forth the computation of basic and diluted net earnings per ordinary share for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Numerator:
Earnings (loss) per share attributable to Enstar ordinary shareholders:
Net earnings (loss) from continuing operations(1)	$	1,711,810	$	897,825	$	(163,232)
Net earnings from discontinued operations(2)	7,534		4,350		878
Net earnings (loss) attributable to Enstar ordinary shareholders	$	1,719,344	$	902,175	$	(162,354)
Denominator:
Weighted-average ordinary shares outstanding — basic(3)	21,551,408		21,482,617		20,698,310
Effect of dilutive securities:
Share-based compensation plans(4)	208,293		227,878		129,746
Warrants	58,593		64,571		76,120

Weighted-average ordinary shares outstanding — diluted	21,818,294		21,775,066		20,904,176
Earnings (loss) per share attributable to Enstar ordinary shareholders:
Basic:
Net earnings (loss) from continuing operations	$	79.43	$	41.80	$	(7.89)
Net earnings from discontinued operations	0.35		0.20		0.05
Net earnings (loss) per ordinary share	$	79.78	$	42.00	$	(7.84)
Diluted (5):
Net earnings (loss) from continuing operations	$	78.45	$	41.23	$	(7.89)
Net earnings from discontinued operations	0.35		0.20		0.05
Net earnings (loss) per ordinary share	$	78.80	$	41.43	$	(7.84)

(3) Weighted-average ordinary shares for basic earnings per share includes ordinary shares (voting and non-voting) but excludes ordinary shares held in the EB Trust in respect of JSOP awards.

Share-Based Compensation and Pensions (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Compensation Cost for Share-based Compensation Plans

The table below provides a summary of the compensation costs for all of our share-based compensation plans for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Share-based compensation plans:
Restricted shares and restricted share units	$	8,286	$	6,564	$	7,641
Performance share units	12,678		23,582		1,968
Cash-settled stock appreciation rights	215		2,575		(3,316)
Joint share ownership plan expense	4,296		—		—
Other share-based compensation plans:
Northshore/Atrium incentive plan	971		3,652		2,792
StarStone incentive plan	(223)		223		—
Deferred compensation and ordinary share plan for non-employee directors	1,183		992		1,155
Employee share purchase plan	339		411		430
Total share-based compensation	$	27,745	$	37,999	$	10,670

The table below summarizes the expense related to our Defined Contribution Plans and our Defined Benefit Plan for the years ended December 31, 2020, 2019 and 2018.


	2020		2019		2018
Defined contribution plans	$	11,791	$	11,798	$	11,434
Defined benefit plan	2,975		684		2,243
Total pension expense	$	14,766	$	12,482	$	13,677

Restricted Shares, Restricted Share Units and Performance Share Units

The following table summarizes the activity related to restricted shares and restricted share awards during 2020:


	Number of Shares	Weighted-Average Share Price
Nonvested — January 1	64,572	$180.49
Granted	70,012	152.28
Vested	(38,961)	174.93
Forfeited	(373)	177.73
Nonvested — December 31	95,250	161.60


Grant Year	Inception-to-date Activity Roll-forward					Performance Criteria: Change in FDBVPS (3 year)								Performance Multiplier Levels Per Award Agreements
	PSUs Granted at Target	Forfeited	Estimated Change in Multiplier	Vested	Unvested at December 31, 2020	Threshold		Target		Target +		Maximum		Threshold		Target		Target +		Maximum
2017	36,321	(12,267)	9,527	(33,581)	—	20.00	%	30.00	%	N/A		40.00	%	50.00	%	100.00	%	N/A		150.00	%
2017	91,875	—	18,100	(109,975)	—	30.30	%	35.65	%	N/A		41.00	%	50.00	%	100.00	%	N/A		150.00	%
2018	39,682	(12,545)	10,218	(6,700)	30,655	25.00	%	32.50	%	N/A		40.00	%	50.00	%	100.00	%	N/A		150.00	%
2019	18,308	(1,758)	7,835	(881)	23,504	20.00	%	30.00	%	N/A		40.00	%	60.00	%	100.00	%	N/A		150.00	%
2020	22,591	(2,151)	—	(701)	19,739	25.00	%	32.50	%	N/A		40.00	%	60.00	%	100.00	%	N/A		150.00	%
2020	52,948	—	—	—	52,948	33.10	%	36.80	%	44.30	%	52.10	%	50.00	%	100.00	%	150.00	%	200.00	%
	261,725	(28,721)	45,680	(151,838)	126,846

The following table summarizes the activity related to PSUs during 2020:


	Number of Shares	Weighted-Average Share Price
Nonvested — January 1	206,949	$185.61
Granted	98,099	167.94
Change in performance multiplier	25,850	179.71
Vested	(153,469)	187.24
Forfeited	(7,442)	146.76
Nonvested — December 31	169,987	174.10

Summary of Performance Share Units and Performance Criteria and Multiplier


Grant Year	Inception-to-date Activity Roll-forward					Performance Criteria: Average Annual Operating ROE						Performance Multiplier Levels Per Award Agreements
	PSUs Granted at Target	Forfeited	Estimated Change in Multiplier	Vested	Unvested at December 31, 2020	Threshold		Target		Maximum		Threshold		Target		Maximum
2019	18,308	(1,756)	7,811	(930)	23,433	9.60	%	12.00	%	14.40	%	60.00	%	100.00	%	150.00	%
2020	22,560	(2,151)	—	(701)	19,708	9.60	%	12.00	%	14.40	%	60.00	%	100.00	%	150.00	%
	40,868	(3,907)	7,811	(1,631)	43,141

Summary of Performance Multipliers

At the end of each reporting period, we estimate the expected performance multiplier, as shown in the table below:


Award Description	2020		2019	2018
2017 FDBVPS Type I (30.00% Target Change)	139%	(1)	139%	50%
2017 FDBVPS Type II (35.65% Target Change)	120%	(1)	120%	50%
2018 FDBVPS	150%	(1)	100%	50%
2019 FDBVPS	150%		100%	N/A
2019 Average Operating ROE	150%		100%	N/A
2020 FDBVPS Type I (32.50% Target Change)	100%		N/A	N/A
2020 Average Operating ROE	100%		N/A	N/A
2020 FDBVPS Type II (36.80% Target Change)	100%		N/A	N/A

(1) Multipliers for the 2017 and 2018 awards are the final achieved terms.

Summary of SARs Activity

The following table summarizes the activity related to SARs during 2020:


	Number of SARs	Weighted-Average Exercise Price of SARs		Weighted-Average Expected Term (in years)	Aggregate Intrinsic Value(1)
Balance, beginning of year	89,227	$	143.33
Exercised	(12,793)	136.94

Balance, end of year	76,434	144.40		1.90	$	4,623

Assumptions Used to Estimate Fair Value of SARs Using Black-Scholes Option Valuation Model

The following table sets forth the assumptions used to estimate the fair value of the SARs using the Black-Scholes option valuation model as of December 31, 2020, 2019 and 2018:


	2020			2019			2018
Weighted-average fair value per SAR	$	78.47		$	76.03		$	45.85
Weighted-average volatility	49.43		%	19.75		%	18.94		%
Weighted-average risk-free interest rate	0.15		%	1.64		%	2.72		%
Dividend yield	0.00		%	0.00		%	0.00		%

Share-Based Compensation Arrangement By Share-Based Payment Award, Valuation Assumptions


	2020

Weighted-average volatility	18.66	%
Weighted-average risk-free interest rate	1.55	%
Dividend yield	0.00	%

Income Taxation (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Earnings before Income Taxes


	2020		2019		2018
Domestic (Bermuda)	$	1,503,505	$	576,338	$	(232,743)
Foreign	231,444		356,878		15,293
Total earnings (loss) before income taxes attributable to continuing operations	$	1,734,949	$	933,216	$	(217,450)

Tax Expense for Income Taxes

The following table presents our current and deferred income tax expense (benefit) attributable to continuing operations by jurisdiction for the years ended December 31, 2020, 2019 and 2018:


	2020		2019		2018
Current:
Domestic (Bermuda)	$	—	$	—	$	—
Foreign	15,232		16,330		(917)
	15,232		16,330		(917)
Deferred:
Domestic (Bermuda)	—		—		—
Foreign	8,595		(3,958)		(2,772)
	8,595		(3,958)		(2,772)
Total income tax expense (benefit) attributable to continuing operations	$	23,827	$	12,372	$	(3,689)

Reconciliation of Earnings before Income Taxes Computed by Applying Effective Rate


	2020			2019			2018
Earnings (loss) before income taxes	$	1,734,949		$	933,216		$	(217,450)
Bermuda income taxes at statutory rate	0.0		%	0.0		%	0.0		%
Foreign income tax rate differential	1.2		%	8.6		%	0.6		%



Change in valuation allowance	0.1		%	(7.2)		%	(1.8)		%


U.S. base erosion and anti-abuse tax	—		%	0.3		%	(0.3)		%


Other	0.1		%	(0.4)		%	3.2		%
Effective tax rate	1.4		%	1.3		%	1.7		%

Components of Deferred Tax Assets and Deferred Tax Liabilities

Significant components of the deferred tax assets and deferred tax liabilities as of December 31, 2020 and 2019 were as follows:


	2020		2019
Deferred tax assets:
Net operating loss carryforwards	$	141,459	$	144,609

Insurance reserves	22,238		7,535
Unearned premiums	68		151

Provisions for bad debt	407		6,172

Defendant asbestos and environmental liabilities	121,006		140,000
Other deferred tax assets	16,696		3,230
Deferred tax assets	301,874		301,697
Valuation allowance	(118,229)		(117,390)
Deferred tax assets, net of valuation allowance	183,645		184,307

Deferred tax liabilities:
Unrealized gains on investments	(20,185)		(14,079)
Lloyd's underwriting profit taxable in future periods	(15,555)		(8,852)
Deferred policy acquisition cost	—		(8,267)
Other deferred tax liabilities	(9,242)		(13,390)
Deferred tax liabilities	(44,982)		(44,588)

Net deferred tax asset	$	138,663	$	139,719

Net Deferred Tax Asset (Liability) Balance by Major Jurisdiction:


	December 31,
	2020		2019
	Net Deferred Tax Asset		Net Deferred Tax Asset

United States	$	156,730	$	154,700
United Kingdom	(18,095)		(16,074)
Other	28		1,093
Total	$	138,663	$	139,719

Summary of Operating Loss Carryforwards

As of December 31, 2020, we had net operating loss carryforwards that could be available to offset future taxable income, as follows:


Tax Jurisdiction	Loss Carryforwards		Tax effect		Expiration
Operating and Capital Loss Carryforwards:
United States - Net operating loss	$	428,732	$	90,034	2024-2038

United Kingdom	185,230		35,194		Indefinitely
Luxembourg	17,200		4,300		2035-2036
Other	48,683		11,931		Indefinitely

Summary of Income Tax Examinations

Listed below are the tax years that remain subject to examination by a major tax jurisdiction as of December 31, 2020:

Major Tax Jurisdiction

Open Tax Years

United States

2017-2020

United Kingdom

2019-2020

Australia

2015-2020

Related Party Transactions (Tables)

12 Months Ended

Dec. 31, 2020

Schedule of Related Party Transactions

The following table presents the amounts included in our consolidated balance sheet related to our related party transactions with Stone Point and its affiliated entities:


	December 31, 2020		December 31, 2019

Short-term investments, AFS, at fair value	$	878	$	1,431
Fixed maturities, trading, at fair value	196,086		269,131
Fixed maturities, AFS, at fair value	227,397		160,303
Equities, at fair value	103,914		121,794
Other investments, at fair value:
Hedge funds	19,844		18,993
Fixed income funds	210,017		381,449

Private equity funds	37,262		34,858
CLO equities	38,658		32,560
CLO equity funds	166,523		87,509


Private Debt	27,016		16,312
Real estate fund	27,278		18,106
Total investments	1,054,873		1,142,446
Cash and cash equivalents	23,933		54,080
Other assets	403		10
Other liabilities	745		4,710
Net investment	$	1,078,464	$	1,191,826

The following table presents the amounts included in net earnings related to our related party transactions with Stone Point and its affiliated entities:


	2020		2019		2018
Net investment income	$	16,325	$	8,733	$	7,424
Net realized and unrealized gains (losses)	23,750		26,631		207
Total net earnings	$	40,075	$	35,364	$	7,631


	2018
Fee income due to Enstar Limited	$	1,453

Transactions under KaylaRe-StarStone QS:
Ceded premium earned	(52,651)
Net incurred losses	31,654
Acquisition costs	18,774




Total net earnings (loss)	$	(770)

Our consolidated balance sheet as of December 31, 2020 and 2019 included the following balances related to transactions with Hillhouse Capital and AnglePoint (as applicable):


	2020			2019
Investments in funds managed by AnglePoint, held by Enhanzed Re	$	851,435		$	327,799
Our ownership percentage of Enhanzed Re	47.4		%	47.4		%
Our share of investments in funds managed by AnglePoint held by Enhanzed Re (through our equity method investment ownership)	$	403,580		$	155,377

Investment in other funds managed by AnglePoint and Hillhouse:
InRe Fund	$	2,365,158		$	918,633
Other funds	369,508			232,968
	$	2,734,666		$	1,151,601

As noted above, Clear Spring was not a related party as of December 31, 2020. Our consolidated balance sheet as of December 31, 2019 included the following balances between us and Clear Spring:


	2019
Balances under StarStone ceding quota share included, in assets or liabilities held-for-sale:
Reinsurance balances recoverable on paid and unpaid losses	$	22,812
Prepaid insurance premiums	51
Ceded payable	3,616
Ceded acquisition costs	21

Balances under assuming quota share:
Losses and LAE	6,135
Unearned reinsurance premiums	13
Funds held	8,611

Our consolidated statement of earnings for the years ended December 31, 2020, 2019 and 2018 included the following amounts between us and Clear Spring:


	2020		2019		2018
Transactions under StarStone ceding quota share, included in net earnings (loss) from discontinued operations:
Ceded premium earned	$	122	$	(14,994)	(29,520)
Net incurred losses and LAE	2,730		6,567		18,143
Acquisition costs	56		356		7,035

Transactions under assuming quota share:
Premium earned	(15)		3,749		7,380
Net incurred losses and LAE	1,014		(2,202)		(4,536)
Acquisition costs	11		(92)		(1,836)

Total net earnings (loss)	$	3,918	$	(6,616)	$	(3,334)

The following table presents the amounts included in net earnings related to our related party transactions with AmTrust:


	2020		2019		2018
Net investment income	$	7,365	$	7,667	$	299
Net realized and unrealized gains	(11,183)		10,086		—
Total net earnings	$	(3,818)	$	17,753	$	299

Our consolidated balance sheet as of December 31, 2020 and 2019 included the following balances between us and Enhanzed Re:


	2020		2019
Balances under ceding quota share:
Reinsurance balances recoverable	$	208,379	$	59,601
Funds held	193,981		50,089
Insurance balances payables	1,276		1,443

Other assets	730		1,033

Our consolidated statement of earnings for the years ended December 31, 2020 and 2019 included the following amounts between us and Enhanzed Re:


	2020		2019
Amounts under ceding quota share:
Ceded premium earned	$	(391)	$	—
Net incurred losses and LAE	(5,977)		—
Acquisition costs	169		73
Net investment income	(4,272)		—
Net realized and unrealized gains	(740)		—
Other income	2,617		—
Fees and commission income	572		749
Total Net earnings	$	(8,022)	$	822

Change in unrealized gains (losses) on AFS investments	$	(2,729)	$	—

Our consolidated balance sheet as of December 31, 2020 included the following balances between us and Core Specialty:


	2020
Balances under assuming quota share, LPT and ADC reinsurances:
Funds held by reinsured companies	$	58,086
Other assets	38,846
Losses and loss adjustment expenses	682,637
Insurance and reinsurance balances payable	24,806
Other liabilities	5,003

Balances under ceding reinsurances:
Reinsurance balances recoverable on paid and unpaid losses	1,736

Balances under service agreements:
Other assets	6,727
Other liabilities	328

Balances under sale and recapitalization agreement:
Other liabilities	4,512

Our consolidated statement of earnings for the year ended December 31, 2020 included the following amounts between us and Core Specialty:


	2020
Transactions under assuming quota share, LPT and ADC reinsurances:
Net premiums earned	$	76
Net incurred losses and loss adjustment expenses	(1,223)
Acquisition costs	458

Transactions under service agreements:
Fees and commission income	4,004

Total net earnings	$	3,315

Dividend Restrictions and Statutory Financial Information (Tables)

12 Months Ended

Dec. 31, 2020

Summary of Statutory Capital and Surplus


	Statutory Capital and Surplus
	Required				Actual				Statutory Income
	2020		2019		2020		2019		2020		2019		2018
Bermuda	$	2,711,687	$	2,138,395	$	5,565,429	$	4,016,663	$	1,850,913	$	643,683	$	29,486
U.K.	803,685		837,104		1,224,208		1,532,751		43,219		154,644		(52,936)
U.S.	185,904		364,507		554,339		861,379		(67,477)		121,406		(75,005)
Europe	95,746		94,334		214,115		229,344		(983)		11,816		(17,611)
Australia	18,858		18,110		58,531		37,815		(1,722)		4,847		1,761

Tabular disclosure of how the entity's reporting under GAAP as of the balance sheet date differs from the results based on prescribed and permitted accounting practices of the state or country of domicile in which a relevant statutory filing is made, or differences in results based on the National Association of Insurance Commissioners (NAIC) prescribed practices, or a combination thereof. Describes the accounting practices used and the related monetary effect on statutory surplus, net income, and risk-based capital. If an insurance enterprise's risk-based capital would have triggered a regulatory event had it not used a permitted practice, that fact is disclosed in the financial statements. Permitted statutory accounting practices include practices not prescribed but allowed by the domiciliary state insurance department regulatory authority.

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2020

Lease, Cost and Other Lease Information

The table below provides the lease cost and other information relating to our operating leases for the years ended December 31, 2020 and 2019:


	2020			2019
Lease cost:
Operating lease cost	$	12,720		$	13,627
Short-term lease cost(1)	246			—
Total lease cost	12,966			13,627
Sub-lease income(2)	(553)			(542)
Total net lease cost	$	12,413		$	13,085

Other information:
Operating cash paid for amounts included in the measurement of lease liabilities	$	13,421		$	11,129
Non-cash activity: right-of-use assets relating to leases	295			57,536

Weighted-average remaining lease term	6.1 years			6.3 years
Weighted-average discount rate	6.5		%	6.3		%

(1) Leases with an initial lease term of twelve months or less are not recognized within our consolidated balance sheets.

Assets And Liabilities, Lessee

The table below provides a summary of the operating leases recorded on our consolidated balance sheets for the years ended December 31, 2020 and 2019:


	Balance sheet classification	2020		2019
Right-of-use assets (1) (2)	Other assets	$	32,297	$	46,747
Current lease liabilities (2)	Other liabilities	7,959		11,403
Non-current lease liabilities (2)	Other liabilities	27,064		34,785

Lessee, Operating Lease, Liability, Maturity

The table below provides a summary of the contractual maturities of our operating lease liabilities:



	2021		2022	2023	2024	2025	2026 and beyond	Total lease payments	Less: Imputed interest	Present value of lease liabilities
Contractual maturities	$	9,774	8,099	7,267	5,561	4,534	8,577	43,812	(8,789)	$	35,023

Segment Information (Tables)

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Summary of Operations by Segment


	2020
	Non-life Run-off		Atrium			StarStone			Other		Total
Gross premiums written	$	5,191	$	206,656		$	326,695		$	13,441	$	551,983

Net premiums written	$	2,987	$	183,194		$	233,202		$	13,441	$	432,824

Net premiums earned	$	58,695	$	175,393		$	318,115		$	19,889	$	572,092
Net incurred losses and LAE	(44,995)		(87,226)			(266,738)			(16,967)		(415,926)

Acquisition costs	(20,177)		(59,611)			(90,797)			(435)		(171,020)
Operating expenses	(200,990)		(13,078)			(81,853)			—		(295,921)
Underwriting income (loss)	(207,467)		15,478			(121,273)			2,487		(310,775)
Net investment income	282,048		5,542			27,443			(12,216)		302,817
Net realized and unrealized gains	1,627,526		4,165			10,328			—		1,642,019
Fees and commission income	19,462		22,984			—			—		42,446
Other income (losses)	99,940		131			3,734			(2,673)		101,132
Corporate expenses	(97,727)		(21,522)			(42,011)			(44,298)		(205,558)
Interest income (expense)	(67,195)		—			(2,110)			9,997		(59,308)
Net foreign exchange gains (losses)	(13,214)		4,327			(10,140)			2,634		(16,393)


EARNINGS (LOSS) BEFORE INCOME TAXES	1,643,373		31,105			(134,029)			(44,069)		1,496,380
Income tax expense	(17,412)		(4,122)			(902)			(1,391)		(23,827)
Earnings from equity method investments	238,569		—			—			—		238,569
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	1,864,530		26,983			(134,931)			(45,460)		1,711,122
Net earnings from discontinued operations, net of income taxes	—		—			16,251			—		16,251
NET EARNINGS (LOSS)	1,864,530		26,983			(118,680)			(45,460)		1,727,373
Net (earnings) loss attributable to noncontrolling interest	1,597		(11,059)			37,133			—		27,671
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	1,866,127		15,924			(81,547)			(45,460)		1,755,044
Dividends on preferred shares	—		—			—			(35,700)		(35,700)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$	1,866,127	$	15,924		$	(81,547)		$	(81,160)	$	1,719,344

Underwriting ratios:
Loss ratio			49.7		%	83.8		%
Acquisition expense ratio			34.0		%	28.5		%
Operating expense ratio			7.5		%	25.8		%
Combined ratio			91.2		%	138.1		%


	2019
	Non-life Run-off		Atrium			StarStone			Other		Total
Gross premiums written	$	(25,069)	$	192,373		$	472,815		$	18,534	$	658,653

Net premiums written	$	(25,338)	$	172,356		$	379,523		$	18,512	$	545,053

Net premiums earned	$	168,496	$	164,059		$	451,112		$	20,380	$	804,047
Net incurred losses and LAE	(51,625)		(77,276)			(469,240)			(16,038)		(614,179)

Acquisition costs	(73,642)		(56,956)			(109,369)			(642)		(240,609)
Operating expenses	(199,756)		(14,452)			(60,627)			—		(274,835)
Underwriting income (loss)	(156,527)		15,375			(188,124)			3,700		(325,576)
Net investment income	275,236		7,049			34,396			(8,410)		308,271
Net realized and unrealized gains	968,350		6,195			31,572			5,849		1,011,966
Fees and commission income	18,293		10,160			—			—		28,453
Other income	34,809		140			329			1,792		37,070
Corporate expenses	(70,689)		(13,825)			(7,790)			(45,945)		(138,249)
Interest income (expense)	(62,055)		—			(475)			9,989		(52,541)
Net foreign exchange gains (losses)	9,918		(504)			(1,505)			3		7,912


EARNINGS (LOSS) BEFORE INCOME TAXES	1,017,335		24,590			(131,597)			(33,022)		877,306
Income tax expense	(7,250)		(4,033)			(1,004)			(85)		(12,372)
Earnings (losses) from equity method investments	56,128		—			(218)			—		55,910
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	1,066,213		20,557			(132,819)			(33,107)		920,844
Net earnings from discontinued operations, net of income taxes	—		—			7,375			—		7,375
NET EARNINGS (LOSS)	1,066,213		20,557			(125,444)			(33,107)		928,219
Net (earnings) loss attributable to noncontrolling interest	(6,409)		(8,432)			24,711			—		9,870
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	1,059,804		12,125			(100,733)			(33,107)		938,089
Dividends on preferred shares	—		—			—			(35,914)		(35,914)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$	1,059,804	$	12,125		$	(100,733)		$	(69,021)	$	902,175

Underwriting ratios:
Loss ratio			47.1		%	104.0		%
Acquisition expense ratio			34.7		%	24.2		%
Operating expense ratio			8.8		%	13.5		%
Combined ratio			90.6		%	141.7		%


	2018
	Non-life Run-off		Atrium			StarStone			Other		Total
Gross premiums written	$	(8,910)	$	171,494		$	622,570		$	32,378	$	817,532

Net premiums written	$	(9,217)	$	153,488		$	478,009		$	32,067	$	654,347

Net premiums earned	$	9,427	$	146,315		$	515,163		$	24,874	$	695,779
Net incurred losses and LAE	306,067		(69,810)			(543,080)			(16,899)		(323,722)

Acquisition costs	(4,006)		(50,646)			(120,517)			(2,686)		(177,855)
Operating expenses	(158,731)		(17,777)			(98,137)			—		(274,645)
Underwriting income (loss)	152,757		8,082			(246,571)			5,289		(80,443)
Net investment income	226,287		5,686			27,000			2,725		261,698
Net realized and unrealized losses	(381,712)		(3,251)			(12,320)			(10,249)		(407,532)
Fees and commission income	16,466		18,622			—			—		35,088
Other income (losses)	35,978		162			(550)			(1,517)		34,073
Corporate expenses	(39,093)		(6,921)			—			(28,127)		(74,141)
Interest income (expense)	(30,616)		—			(103)			5,023		(25,696)
Net foreign exchange gains (losses)	2,534		(3,394)			(2,832)			1,048		(2,644)


EARNINGS (LOSS) BEFORE INCOME TAXES	(17,399)		18,986			(235,376)			(25,808)		(259,597)
Income tax benefit (expense)	3,581		(3,732)			3,892			(52)		3,689
Earnings from equity method investments	42,147		—			—			—		42,147
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	28,329		15,254			(231,484)			(25,860)		(213,761)
Net earnings from discontinued operations, net of income taxes	—		—			1,489			—		1,489
NET EARNINGS (LOSS)	28,329		15,254			(229,995)			(25,860)		(212,272)
Net (earnings) loss attributable to noncontrolling interest	(3,107)		(6,257)			71,415			—		62,051
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	25,222		8,997			(158,580)			(25,860)		(150,221)
Dividend on preferred shares	—		—			—			(12,133)		(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$	25,222	$	8,997		$	(158,580)		$	(37,993)	$	(162,354)

Underwriting ratios:
Loss ratio			47.7		%	105.4		%
Acquisition expense ratio			34.6		%	23.4		%
Operating expense ratio			12.2		%	19.1		%
Combined ratio			94.5		%	147.9		%

Schedule of Revenue from External Customers


	Non-life Run-off			Atrium			StarStone			Other			Total
	Total		%	Total		%	Total		%	Total		%	Total		%
	(In thousands of U.S. dollars, except percentages)
United States	$	4,969	95.7	$	103,411	50.1	$	61,104	18.7	$	13,441	100.0	$	182,925	33.2
United Kingdom	(229)		(4.4)	14,054		6.8	105,057		32.2	—		—	118,882		21.5
Europe	1,615		31.1	19,705		9.5	62,181		19.0	—		—	83,501		15.1
Asia	—		—	7,834		3.8	60,262		18.4	—		—	68,096		12.3
Rest of World	(1,164)		(22.4)	61,652		29.8	38,091		11.7	—		—	98,579		17.9
Total	$	5,191	100.0	$	206,656	100.0	$	326,695	100.0	$	13,441	100.0	$	551,983	100.0

Summary of Company's Assets by Segment

Our total assets as of December 31, 2020 and 2019 by segment and for our other activities were as follows:


	2020		2019
Assets by Segment:
Non-life Run-off (1)	$	19,062,400	$	15,775,409
Atrium (2)	615,778		580,405
StarStone	2,583,247		3,985,137
Other	(614,141)		(514,852)
Total assets	$	21,647,284	$	19,826,099

(2) The total assets within the Atrium segment are all included within Northshore's held-for-sale assets in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations".

Unaudited Condensed Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Unaudited Condensed Quarterly Financial Data


	December 31,				September 30,				June 30,				March 31,
	2020		2019		2020		2019		2020		2019		2020		2019
INCOME
Net premiums earned	$	108,146	$	185,336	$	161,724	$	175,802	$	142,871	$	190,962	$	159,351	$	251,947
Fees and commission income	14,121		9,522		10,787		6,437		10,010		6,017		7,528		6,477
Net investment income	61,530		76,847		72,130		81,502		94,443		74,271		74,714		75,651
Net realized and unrealized gains (losses)	803,467		153,477		500,005		145,060		967,608		260,669		(629,061)		452,760
Other income (losses)	33,372		21,703		48,404		822		(1,087)		8,831		20,443		5,714
	1,020,636		446,885		793,050		409,623		1,213,845		540,750		(367,025)		792,549
EXPENSES
Net incurred losses and loss adjustment expenses	76,248		48,068		109,686		163,258		186,692		146,554		43,300		256,299

Acquisition costs	38,202		78,417		37,708		33,310		49,067		51,081		46,043		77,801
General and administrative expenses	142,394		116,780		115,828		97,365		144,830		100,676		98,427		98,263
Interest expense	16,872		13,519		15,003		14,950		14,018		13,036		13,415		11,036
Net foreign exchange losses (gains)	15,018		12,186		8,156		(13,665)		5,158		(2,579)		(11,939)		(3,854)

	288,734		268,970		286,381		295,218		399,765		308,768		189,246		439,545
EARNINGS (LOSS) BEFORE INCOME TAXES	731,902		177,915		506,669		114,405		814,080		231,982		(556,271)		353,004
Income tax benefit (expense)	1,468		12,893		(13,915)		(13,465)		(16,652)		(7,698)		5,272		(4,102)
Earnings (losses) from equity method investments	85,844		11,722		149,065		17,703		(8,790)		17,713		12,450		8,772
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	819,214		202,530		641,819		118,643		788,638		241,997		(538,549)		357,674
Net earnings (loss) from discontinued operations, net of income taxes	15,441		(4,666)		4,031		7,916		(1,152)		(3,943)		(2,069)		8,068
NET EARNINGS (LOSS)	834,655		197,864		645,850		126,559		787,486		238,054		(540,618)		365,742
Net (earnings) loss attributable to noncontrolling interest	(3,131)		4,900		(21,912)		109		19,992		2,713		32,722		2,148
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	831,524		202,764		623,938		126,668		807,478		240,767		(507,896)		367,890
Dividends on preferred shares	(8,925)		(8,925)		(8,925)		(8,925)		(8,925)		(8,925)		(8,925)		(9,139)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$	822,599	$	193,839	$	615,013	$	117,743	$	798,553	$	231,842	$	(516,821)	$	358,751

Earnings (loss) per ordinary share attributable to Enstar ordinary shareholders:
Basic:
Net earnings (loss) from continuing operations	$	37.91	$	9.15	$	28.39	$	5.26	$	37.06	$	10.90	$	(23.93)	$	16.49
Net earnings (loss) from discontinued operations	0.33		(0.13)		0.11		0.22		(0.03)		(0.11)		(0.05)		0.22
Basic	$	38.24	$	9.02	$	28.50	$	5.48	$	37.03	$	10.79	$	(23.98)	$	16.71
Diluted(1):
Net earnings (loss) from continuing operations	$	37.47	$	9.02	$	28.13	$	5.21	$	36.68	$	10.81	$	(23.93)	$	16.35
Net earnings (loss) from discontinued operations	0.32		(0.13)		0.11		0.21		(0.03)		(0.11)		(0.05)		0.22
Net earnings (loss) per ordinary share	$	37.79	$	8.89	$	28.24	$	5.42	$	36.65	$	10.70	$	(23.98)	$	16.57

Description of Business - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020 Segment
Segment Reporting Information [Line Items]
Number of segments	3
Atrium
Segment Reporting Information [Line Items]
Syndicate underwriting capacity percentage	25.00%

Significant Accounting Policies (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease to retained earnings	$ 4,647,312	$ 2,887,892
Reinsurance recoverable, allowance for credit loss	137,122	147,639	$ 156,732
Allowance for credit losses	$ 322	0
Cumulative effect of change in accounting principle
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease to retained earnings		6,100
Financial instruments, allowance for credit loss		3,000
Reinsurance recoverable, allowance for credit loss		(195)	$ 0
Allowance for credit losses		$ 3,059

Business Acquisitions - Additional Information (Details)				3 Months Ended	6 Months Ended
	Oct. 30, 2019 USD ($)	Dec. 27, 2018 USD ($)	May 14, 2018 USD ($) $ / shares shares	Jun. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	May 13, 2018
Business Acquisition [Line Items]
Asbestos and environmental liabilities						$ 2,100,000,000	$ 2,300,000,000
Goodwill						$ 62,959,000	$ 109,807,000	$ 109,807,000
Ownership percentage						47.40%	47.40%
Morse TEC
Business Acquisition [Line Items]
Cash paid	$ 0
Asbestos and environmental liabilities	700,000,000
Goodwill	0
Gain on bargain purchase	0
Intangible assets acquired	0
Gain on bargain purchase	$ 0
Maiden Re
Business Acquisition [Line Items]
Cash paid		$ 286,375,000
Goodwill		$ 0
KaylaRe
Business Acquisition [Line Items]
Goodwill			$ 41,736,000
Number of Enstar ordinary shares issued (shares) \| shares			2,007,017
Closing price of shares (dollars per share) \| $ / shares			$ 206.65
Ownership percentage acquired			51.80%
Price-to-book multiple			1.05
Gain recognized on remeasurement of previously held equity method investment to fair value				$ 16,000,000.0	$ 16,007,000
Loss on settlement of preexisting relationships				$ 15,600,000	$ 15,600,000
Ordinary Shares \| KaylaRe
Business Acquisition [Line Items]
Number of Enstar ordinary shares issued (shares) \| shares			1,501,778
Series E non-voting convertible ordinary shares \| KaylaRe
Business Acquisition [Line Items]
Number of Enstar ordinary shares issued (shares) \| shares			505,239
KaylaRe
Business Acquisition [Line Items]
Ownership percentage									48.20%

Business Acquisitions - Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed as of Date of Acquisition (Details) - USD ($) $ in Thousands	Oct. 30, 2019	Dec. 27, 2018	May 14, 2018
Morse TEC
ASSETS
Cash and cash equivalents	$ 171,412
Deferred tax assets	140,000
Other assets - insurance balances receivable	371,116
TOTAL ASSETS	682,528
LIABILITIES
Defendant asbestos and environmental liabilities	662,507
Other liabilities	20,021
TOTAL LIABILITIES	682,528
NET ASSETS ACQUIRED AT FAIR VALUE	$ 0
Maiden Re
ASSETS
Cash and cash equivalents		$ 12,035
Restricted cash and cash equivalents		26,871
Other assets		96,669
Premiums receivable		138,378
Prepaid reinsurance premiums		3,257
Reinsurance balances recoverable		87,018
TOTAL ASSETS		1,466,329
Fixed maturities, trading, at fair value		1,098,593
Short-term investments, trading, at fair value		3,508
Total investments		1,102,101
LIABILITIES
Other liabilities		56,618
Losses and LAE		1,027,367
Unearned premiums		85,696
TOTAL LIABILITIES		1,169,681
NET ASSETS ACQUIRED AT FAIR VALUE		$ 296,648
KaylaRe
ASSETS
Cash and cash equivalents			$ 5,657
Other assets			614
Premiums receivable			10,965
Deferred acquisition costs			275
TOTAL ASSETS			770,380
Fixed maturities, trading, at fair value			126,393
Short-term investments, trading, at fair value			626,476
Total investments			752,869
LIABILITIES
Other liabilities			9,004
Losses and LAE			4,059
Unearned premiums			10,984
Insurance and reinsurance balances payable			13
TOTAL LIABILITIES			24,060
NET ASSETS ACQUIRED AT FAIR VALUE			$ 746,320

Business Acquisitions - Results of Operations Of Acquiree (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Morse TEC
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net investment income	$ 488
General and administrative expenses	(1,459)
Other expenses	(1,512)
Earnings of acquiree since acquisition date	(2,483)
Maiden Re
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net investment income	675
General and administrative expenses	(435)
Net unrealized gains	3,749
Earnings of acquiree since acquisition date	$ 3,989
KaylaRe
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net investment income		$ 3,096
General and administrative expenses		(2,164)
Net unrealized gains		(47,769)
Earnings of acquiree since acquisition date		(45,915)
Premiums earned		13,627
Incurred losses and LAE		(12,364)
Acquisition costs		(341)
Underwriting income		$ 922

Business Acquisitions - Purchase Price and Fair Value of Assets Acquired (Details) $ / shares in Units, $ in Thousands			3 Months Ended	6 Months Ended
	Dec. 27, 2018 USD ($)	May 14, 2018 USD ($) $ / shares shares	Jun. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	May 13, 2018 USD ($)
Purchase Price
Excess of purchase price over fair value of net assets acquired					$ 62,959	$ 109,807	$ 109,807
Fair Value of Previously Held Equity Method Investment
Carrying value of previously held equity method investment prior to the close of the transaction					$ 832,295	$ 326,277
Maiden Re
Purchase Price
Cash paid	$ 286,375
Adjustment for the fair value of preexisting relationships	10,273
Purchase price	296,648
Net assets acquired at fair value	296,648
Excess of purchase price over fair value of net assets acquired	$ 0
KaylaRe
Purchase Price
Adjustment for the fair value of preexisting relationships		$ 37,169
Value of ordinary shares issued		414,750
Fair value of previously held equity method investment		336,137
Purchase price		788,056
Net assets acquired at fair value		746,320
Excess of purchase price over fair value of net assets acquired		$ 41,736
Fair Value of Enstar Ordinary Shares Issued
Number of Enstar ordinary shares issued (shares) \| shares		2,007,017
Closing price of shares (dollars per share) \| $ / shares		$ 206.65
Fair value of Enstar ordinary shares issued to shareholders of KaylaRe		$ 414,750
Fair Value of Previously Held Equity Method Investment
Price-to-book multiple		1.05
Fair value of previously held equity method investment prior to the close of the transaction		$ 336,137
Gain recognized on remeasurement of previously held equity method investment to fair value			$ 16,000	$ 16,007
KaylaRe
Fair Value of Previously Held Equity Method Investment
Carrying value of previously held equity method investment prior to the close of the transaction								$ 320,130

Business Acquisitions - Loss on Settlement Of Contractual Preexisting Relationships (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 14, 2018	Dec. 31, 2017
ASSETS
Funds held by reinsured companies	$ 635,819	$ 475,732
Deferred acquisition costs/Value of business acquired	238,602	272,462	$ 86,585		$ 80,192
TOTAL ASSETS	21,647,284	19,826,099
LIABILITIES
Losses and LAE	10,593,282	9,868,404	$ 9,048,796		$ 7,100,488
Insurance and reinsurance balances payable	494,412	420,546
Other liabilities	942,905	994,584
TOTAL LIABILITIES	14,593,844	14,530,957
NET ASSETS (LIABILITIES)	$ 6,688,004	$ 4,856,351
Carrying value \| KaylaRe
ASSETS
Funds held by reinsured companies				$ 386,793
Deferred acquisition costs/Value of business acquired				33,549
TOTAL ASSETS				420,342
LIABILITIES
Losses and LAE				339,747
Unearned premiums				105,602
Insurance and reinsurance balances payable				25,897
Other liabilities				1,864
TOTAL LIABILITIES				473,110
NET ASSETS (LIABILITIES)				(52,768)
Fair value \| KaylaRe
ASSETS
Funds held by reinsured companies				386,793
Deferred acquisition costs/Value of business acquired				40,268
TOTAL ASSETS				427,061
LIABILITIES
Losses and LAE				333,205
Unearned premiums				105,602
Insurance and reinsurance balances payable				23,559
Other liabilities				1,864
TOTAL LIABILITIES				464,230
NET ASSETS (LIABILITIES)				(37,169)
Loss on deemed settlement \| KaylaRe
ASSETS
Funds held by reinsured companies				0
Deferred acquisition costs/Value of business acquired				6,719
TOTAL ASSETS				6,719
LIABILITIES
Losses and LAE				(6,542)
Unearned premiums				0
Insurance and reinsurance balances payable				(2,338)
Other liabilities				0
TOTAL LIABILITIES				(8,880)
NET ASSETS (LIABILITIES)				$ 15,599

Significant New Business (Details) - USD ($) $ in Thousands	Feb. 25, 2021	Feb. 05, 2021	Jan. 15, 2021	Jan. 08, 2021	Oct. 01, 2020	Aug. 06, 2020	Jul. 01, 2020	Jun. 01, 2020	Mar. 31, 2020	Oct. 01, 2019	Aug. 05, 2019	Apr. 11, 2019	Feb. 14, 2019	Dec. 31, 2018	Dec. 27, 2018	Aug. 01, 2018	Feb. 23, 2018	Feb. 16, 2018	Jan. 29, 2018
Hannover Re
Schedule of Investments [Line Items]
Total Assets Assumed						$ 182,498
Total Liabilities Assumed						209,713
Fair Value Adjustment						$ (27,215)
Munich Re
Schedule of Investments [Line Items]
Total Assets Assumed							$ 100,956
Total Liabilities Assumed							$ 100,956
AXA Group
Schedule of Investments [Line Items]
Total Assets Assumed								$ 179,681
Total Liabilities Assumed								179,681
Percentage ceded					10.00%
Aspen
Schedule of Investments [Line Items]
Total Assets Assumed								770,000
Deferred Charge Asset								11,746
Total Liabilities Assumed								$ 781,746
Lyft
Schedule of Investments [Line Items]
Total Assets Assumed									$ 465,000
Total Liabilities Assumed									$ 465,000
Zurich
Schedule of Investments [Line Items]
Total Assets Assumed										$ 507,061
Deferred Charge Asset										115,815
Total Liabilities Assumed										$ 622,876
Maiden Re Bermuda
Schedule of Investments [Line Items]
Total Assets Assumed											$ 445,000				$ 70,425
Deferred Charge Asset											85,183				1,704
Total Liabilities Assumed											$ 530,183				$ 72,129
Amerisure
Schedule of Investments [Line Items]
Total Assets Assumed												$ 45,463
Deferred Charge Asset												2,873
Total Liabilities Assumed												$ 48,336
AmTrust
Schedule of Investments [Line Items]
Total Assets Assumed													$ 1,143,949
Deferred Charge Asset													20,633
Total Liabilities Assumed													$ 1,164,582
Allianz SE
Schedule of Investments [Line Items]
Total Assets Assumed														$ 70,000
Total Liabilities Assumed														$ 70,000
Coca-Cola
Schedule of Investments [Line Items]
Total Assets Assumed																$ 103,617
Deferred Charge Asset																17,208
Total Liabilities Assumed																$ 120,825
Zurich Australia
Schedule of Investments [Line Items]
Total Assets Assumed																	$ 268,657
Total Liabilities Assumed																	280,764
Fair Value Adjustment																	$ (12,107)
Neon
Schedule of Investments [Line Items]
Total Assets Assumed																		$ 525,673
Total Liabilities Assumed																		546,298
Fair Value Adjustment																		$ (20,625)
Novae
Schedule of Investments [Line Items]
Total Assets Assumed																			$ 1,095,730
Total Liabilities Assumed																			1,163,198
Fair Value Adjustment																			$ (67,468)
Subsequent Event \| AXA Group
Schedule of Investments [Line Items]
Total Liabilities Assumed	$ 1,395,000
Subsequent Event \| ProSight
Schedule of Investments [Line Items]
Total Liabilities Assumed			$ 500,000
Subsequent Event \| CNA
Schedule of Investments [Line Items]
Total Liabilities Assumed		$ 690,000
Subsequent Event \| Liberty Mutual
Schedule of Investments [Line Items]
Total Liabilities Assumed				$ 420,000

Divestitures, Held-For-Sale Businesses and Discontinued Operations - Additional Information (Details) $ in Thousands, € in Millions					3 Months Ended	6 Months Ended	12 Months Ended
	Nov. 30, 2020 USD ($)	Oct. 14, 2020 USD ($)	Oct. 14, 2020 EUR (€)	Oct. 02, 2020 USD ($)	Dec. 31, 2020 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jan. 01, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership %					47.40%		47.40%	47.40%
Assumed business							$ 2,186,024	$ 1,586,307	$ 1,772,104
Equity method investments					$ 832,295		$ 832,295	326,277
StarStone US
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assumed business	$ 462,400
Reinsurance premium consideration	478,200
Additional consideration	130,000
Atrium
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Syndicate underwriting capacity percentage							25.00%
Held-for-sale or disposed of by sale, not discontinued operations \| Northshore
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restricted investments					94,400		$ 94,400
Discontinued operations, disposed of by sale \| StarStone US
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received	235,000				281,989		281,989
Cash consideration received	$ 47,000
Not discontinued operations, disposed of by sale \| Vander Haeghen & CO SA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales of subsidiaries, net of cash sold		$ 4,500	€ 3.8
Gain on sale of subsidiary					3,400
Discontinued operations, held-for-sale \| StarStone US
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restricted investments								131,000
Cash inflows (outflows)							99,200	$ (53,900)	$ (64,600)
Scenario, Forecast
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments to acquire investments						$ 27,000
Scenario, Forecast \| Held-for-sale or disposed of by sale, not discontinued operations \| SUL
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales of subsidiaries, net of cash sold						30,000
Core Specialty
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership %										25.23%
Equity method investments					235,000		235,000
Core Specialty \| Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership %										25.23%
Inigo
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Investment, fair value					$ 16,900		$ 16,900
Trident \| Scenario, Forecast
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments to acquire investments						$ 18,000
Starstone International
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of renewal rights				$ 500
North Bay
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by parent					59.00%		59.00%
North Bay \| Trident
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners					39.30%		39.30%
North Bay \| Dowling
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners					1.70%		1.70%
SSHL
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by parent					59.00%		59.00%
SSHL \| Trident
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners					39.30%		39.30%
SSHL \| Dowling
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners					1.70%		1.70%
SSHL \| North Bay
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by parent					100.00%		100.00%
Northshore \| Trident \| Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners										76.30%
Northshore \| Dowling \| Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners										1.60%
Northshore \| North Bay
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by parent					92.10%		92.10%
Northshore \| Core Specialty \| Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners										13.80%
Core Specialty \| Dowling \| Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners										0.40%
SUL
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by parent					59.00%		59.00%
SUL \| Trident
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners					39.30%		39.30%
SUL \| Dowling
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners					1.70%		1.70%
Inigo \| Scenario, Forecast
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by parent						5.40%

Divestitures, Held-For-Sale Businesses and Discontinued Operations - Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Nov. 30, 2020
ASSETS
TOTAL ASSETS HELD-FOR-SALE	$ 711,278				$ 1,474,770				$ 711,278	$ 1,474,770
LIABILITIES
TOTAL LIABILITIES HELD-FOR-SALE	483,657				1,208,531				483,657	1,208,531
DISPOSAL
Reclassification to earnings on disposal of subsidiary									(34)	0	$ 0
NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES	15,441	$ 4,031	$ (1,152)	$ (2,069)	(4,666)	$ 7,916	$ (3,943)	$ 8,068	16,251	7,375	1,489
Northshore \| Held-for-sale or disposed of by sale, not discontinued operations
ASSETS
Other investments, at fair value	9,897								9,897
Total investments	173,126								173,126
Cash and cash equivalents	71,156								71,156
Restricted cash and cash equivalents	152,044								152,044
Premiums receivable	62,392								62,392
Reinsurance balances recoverable on paid and unpaid losses	37,341								37,341
Funds held by reinsured companies	32,226								32,226
Deferred acquisition costs	24,000								24,000
Other assets	182,993								182,993
TOTAL ASSETS HELD-FOR-SALE	711,278								711,278
LIABILITIES
Losses and loss adjustment expenses	254,149								254,149
Unearned premiums	91,400								91,400
Insurance and reinsurance balances payable	12,393								12,393
Debt obligations	39,850								39,850
Other liabilities	177,265								177,265
TOTAL LIABILITIES HELD-FOR-SALE	483,657								483,657
NET ASSETS HELD-FOR-SALE	227,621								227,621
Northshore \| Held-for-sale or disposed of by sale, not discontinued operations \| Short-term Investments
ASSETS
AFS, at fair value	1,720								1,720
Northshore \| Held-for-sale or disposed of by sale, not discontinued operations \| Fixed maturity investments, trading
ASSETS
AFS, at fair value	7,483								7,483
Fixed maturities, trading, at fair value	154,026								154,026
StarStone US \| Discontinued operations, held-for-sale
ASSETS
AFS, at fair value					375,337					375,337
Fixed maturities, trading, at fair value					202,994					202,994
Equities, at fair value					3,000					3,000
Other investments, at fair value					6,389					6,389
Total investments					587,720					587,720
Cash and cash equivalents					78,613					78,613
Restricted cash and cash equivalents					5,815					5,815
Premiums receivable					99,367					99,367
Deferred tax assets					15,191					15,191
Reinsurance balances recoverable on paid and unpaid losses					530,604					530,604
Funds held by reinsured companies					35,861					35,861
Deferred acquisition costs					36,992					36,992
Goodwill and intangible assets					24,900					24,900
Other assets					59,707					59,707
TOTAL ASSETS HELD-FOR-SALE					1,474,770					1,474,770
LIABILITIES
Losses and loss adjustment expenses					836,761					836,761
Unearned premiums					218,166					218,166
Insurance and reinsurance balances payable					22,453					22,453
Other liabilities					131,151					131,151
TOTAL LIABILITIES HELD-FOR-SALE					1,208,531					1,208,531
NET ASSETS HELD-FOR-SALE					$ 266,239					266,239
Discontinued Operation, Continuing Involvement [Abstract]
Discontinued Operation, Intra-Entity Amounts, Discontinued Operation after Disposal, Revenue									11,911	10,672	98,402
Discontinued Operation, Intra-Entity Amounts, Discontinued Operation after Disposal, Income (Expense)									(16,397)	62,515	113,952
Discontinued Operation, Intra-Entity Amounts, Discontinued Operation After Disposal, Income (Loss) From Continuing Operations									28,308	(51,843)	(15,550)
StarStone US \| Discontinued operations, disposed of by sale
INCOME
Net premiums earned									291,326	350,814	199,796
Net investment income									12,849	15,606	10,572
Net realized and unrealized gains									5,431	19,385	(5,352)
Other income									49	9	10
Total income									309,655	385,814	205,026
EXPENSES
Net incurred losses and loss adjustment expenses									191,844	258,396	130,303
Acquisition costs									57,640	65,342	14,935
General and administrative expenses									60,236	60,003	58,590
Interest expense									2,066	2,600	2,120
Net foreign exchange (gains) losses									(13)	33	24
Total expenses									311,773	386,374	205,972
EARNINGS (LOSS) BEFORE INCOME TAXES									(2,118)	(560)	(946)
Income tax benefit									2,255	7,935	2,435
NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES, BEFORE GAIN ON SALE									137	7,375	1,489
DISPOSAL
Consideration received	281,989								281,989			$ 235,000
Less: Carrying value of subsidiary	$ (277,697)								(277,697)
Reclassification to earnings on disposal of subsidiary									11,822
Gain on sale of subsidiary									16,114
NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES									16,251	7,375	1,489
Net loss (earnings) from discontinued operations attributable to noncontrolling interest									(8,717)	(3,025)	(611)
NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS									$ 7,534	$ 4,350	$ 878

Investments - Asset Types (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	$ 3,658,895,000	$ 1,666,387,000
Total investments	9,319,179,000	9,034,557,000
U.S. government and agency
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	717,998,000	381,244,000
Total investments	951,048,000	696,077,000
U.K. government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	13,574,000	15,349,000
Total investments	51,082,000	161,772,000
Other government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	150,127,000	85,147,000
Total investments	502,153,000	702,856,000
Corporate
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	1,937,349,000	880,472,000
Total investments	5,686,732,000	5,448,270,000
Municipal
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	30,032,000	3,780,000
Total investments	162,669,000	140,687,000
Residential mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	328,871,000	99,188,000
Total investments	553,945,000	400,914,000
Commercial mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	276,488,000	49,046,000
Total investments	854,090,000	813,746,000
Asset-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	204,456,000	152,161,000
Total investments	557,460,000	670,235,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	458,100,000	333,300,000
Senior Secured Debt Securities
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	31,400,000
Short-term Investments
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	5,129,000	51,490,000
Debt securities, available-for-sale	263,795,000	128,335,000
Short-term Investments \| U.S. government and agency
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Debt securities, available-for-sale	243,556,000	111,583,000
Short-term Investments \| U.K. government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	24,411,000
Debt securities, available-for-sale	0	1,069,000
Short-term Investments \| Other government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	3,424,000	21,958,000
Debt securities, available-for-sale	3,213,000	387,000
Short-term Investments \| Corporate
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	1,705,000	5,121,000
Debt securities, available-for-sale	17,026,000	13,915,000
Short-term Investments \| Municipal
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Debt securities, available-for-sale	0	1,381,000
Short-term Investments \| Residential mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Debt securities, available-for-sale	0	0
Short-term Investments \| Commercial mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Debt securities, available-for-sale	0	0
Short-term Investments \| Asset-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Debt securities, available-for-sale	0	0
Fixed Maturities
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	4,594,892,000	6,143,335,000
Debt securities, available-for-sale	3,395,100,000	1,538,052,000
Fixed Maturities \| U.S. government and agency
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	123,874,000	208,296,000
Debt securities, available-for-sale	474,442,000	269,661,000
Fixed Maturities \| U.K. government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	37,508,000	122,012,000
Debt securities, available-for-sale	13,574,000	14,280,000
Fixed Maturities \| Other government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	327,437,000	575,017,000
Debt securities, available-for-sale	146,914,000	84,760,000
Fixed Maturities \| Corporate
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	3,227,726,000	3,959,288,000
Debt securities, available-for-sale	1,920,323,000	866,557,000
Fixed Maturities \| Municipal
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	79,959,000	87,451,000
Debt securities, available-for-sale	30,032,000	2,399,000
Fixed Maturities \| Residential mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	154,471,000	215,521,000
Debt securities, available-for-sale	328,871,000	99,188,000
Fixed Maturities \| Commercial mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	347,225,000	534,357,000
Debt securities, available-for-sale	276,488,000	49,046,000
Fixed Maturities \| Asset-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	296,692,000	441,393,000
Debt securities, available-for-sale	204,456,000	152,161,000
Funds Held - Directly Managed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	1,060,263,000	1,173,345,000
Funds Held - Directly Managed \| U.S. government and agency
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	109,176,000	106,537,000
Funds Held - Directly Managed \| U.K. government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Funds Held - Directly Managed \| Other government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	21,165,000	20,734,000
Funds Held - Directly Managed \| Corporate
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	519,952,000	603,389,000
Funds Held - Directly Managed \| Municipal
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	52,678,000	49,456,000
Funds Held - Directly Managed \| Residential mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	70,603,000	86,205,000
Funds Held - Directly Managed \| Commercial mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	230,377,000	230,343,000
Funds Held - Directly Managed \| Asset-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	$ 56,312,000	$ 76,681,000

Investments - Contractual Maturities (Details) - Short-term investments and fixed maturities $ in Thousands	Dec. 31, 2020 USD ($)
Amortized Cost
One year or less	$ 489,559
More than one year through two years	710,621
More than two years through five years	2,097,923
More than five years through ten years	1,974,838
More than ten years	1,544,533
Fixed maturity investments, at amortized cost	8,758,895
Fair Value
One year or less	494,490
More than one year through two years	726,331
More than two years through five years	2,206,020
More than five years through ten years	2,151,191
More than ten years	1,775,652
Trading securities, debt	$ 9,319,179
% of Total Fair Value
One year or less	5.30%
More than one year through two years	7.80%
More than two years through five years	23.70%
More than five years through ten years	23.10%
More than ten years	19.00%
Trading securities, percentage of fair value	100.00%
Residential mortgage-backed
Amortized Cost
Securities without single maturity date	$ 545,628
Fair Value
Securities without single maturity date	$ 553,945
% of Total Fair Value
Securities without single maturity date	5.90%
Commercial mortgage-backed
Amortized Cost
Securities without single maturity date	$ 828,155
Fair Value
Securities without single maturity date	$ 854,090
% of Total Fair Value
Securities without single maturity date	9.20%
Asset-backed
Amortized Cost
Securities without single maturity date	$ 567,638
Fair Value
Securities without single maturity date	$ 557,460
% of Total Fair Value
Securities without single maturity date	6.00%

Investments - Available-for-sale Portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 3,576,641	$ 1,666,126
Gross Unrealized Gains	88,514	5,608
Non-Credit Related Losses	(5,938)	(5,347)
Investments, allowance for credit losses	(322)	0
Fair Value	3,658,895	1,666,387
U.S. government and agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	715,527	381,488
Gross Unrealized Gains	3,305	78
Non-Credit Related Losses	(834)	(322)
Investments, allowance for credit losses	0
Fair Value	717,998	381,244
U.K. government
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	12,494	15,067
Gross Unrealized Gains	1,080	282
Non-Credit Related Losses	0	0
Investments, allowance for credit losses	0
Fair Value	13,574	15,349
Other government
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	142,459	84,116
Gross Unrealized Gains	7,721	1,119
Non-Credit Related Losses	(53)	(88)
Investments, allowance for credit losses	0	0
Fair Value	150,127	85,147
Corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,873,184	880,667
Gross Unrealized Gains	65,913	3,739
Non-Credit Related Losses	(1,567)	(3,934)
Investments, allowance for credit losses	(181)	0
Fair Value	1,937,349	880,472
Municipal
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	28,881	3,770
Gross Unrealized Gains	1,155	12
Non-Credit Related Losses	(4)	(2)
Investments, allowance for credit losses	0
Fair Value	30,032	3,780
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	326,268	99,646
Gross Unrealized Gains	3,292	221
Non-Credit Related Losses	(689)	(679)
Investments, allowance for credit losses	0	0
Fair Value	328,871	99,188
Commercial mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	273,516	49,219
Gross Unrealized Gains	5,202	30
Non-Credit Related Losses	(2,097)	(203)
Investments, allowance for credit losses	(133)	0
Fair Value	276,488	49,046
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	204,312	152,153
Gross Unrealized Gains	846	127
Non-Credit Related Losses	(694)	(119)
Investments, allowance for credit losses	(8)	0
Fair Value	$ 204,456	$ 152,161

Investments - Gross Unrealized Losses (Details) $ in Thousands	Dec. 31, 2020 USD ($) Security	Dec. 31, 2019 USD ($) Security
Fair Value
12 Months or Greater	$ 4,664	$ 3,962
Less Than 12 Months	527,618	760,469
Total	532,282	764,431
Gross Unrealized Losses
12 Months or Greater	(163)	(329)
Less Than 12 Months	(4,805)	(5,018)
Total	$ (4,968)	$ (5,347)
Number of securities in unrealized loss position \| Security	407	479
Number of securities in unrealized loss position, twelve months or longer \| Security	2	12
U.S. government and agency
Fair Value
12 Months or Greater	$ 0	$ 0
Less Than 12 Months	55,839	193,574
Total	55,839	193,574
Gross Unrealized Losses
12 Months or Greater	0	0
Less Than 12 Months	(834)	(322)
Total	(834)	(322)
UK government
Fair Value
12 Months or Greater	0
Less Than 12 Months	0
Total	0
Gross Unrealized Losses
12 Months or Greater	0
Less Than 12 Months	0
Total	0
Other government
Fair Value
12 Months or Greater	0	1,080
Less Than 12 Months	7,971	37,796
Total	7,971	38,876
Gross Unrealized Losses
12 Months or Greater	0	(23)
Less Than 12 Months	(53)	(65)
Total	(53)	(88)
Corporate
Fair Value
12 Months or Greater	0	2,754
Less Than 12 Months	199,048	338,965
Total	199,048	341,719
Gross Unrealized Losses
12 Months or Greater	0	(306)
Less Than 12 Months	(1,224)	(3,628)
Total	(1,224)	(3,934)
Municipal
Fair Value
12 Months or Greater	0	128
Less Than 12 Months	1,690	761
Total	1,690	889
Gross Unrealized Losses
12 Months or Greater	0	0
Less Than 12 Months	(4)	(2)
Total	(4)	(2)
Residential mortgage-backed
Fair Value
12 Months or Greater	4,626	0
Less Than 12 Months	79,149	52,005
Total	83,775	52,005
Gross Unrealized Losses
12 Months or Greater	(125)	0
Less Than 12 Months	(564)	(679)
Total	(689)	(679)
Commercial mortgage-backed
Fair Value
12 Months or Greater	38	0
Less Than 12 Months	67,094	35,777
Total	67,132	35,777
Gross Unrealized Losses
12 Months or Greater	(38)	0
Less Than 12 Months	(1,562)	(203)
Total	(1,600)	(203)
Asset-backed
Fair Value
12 Months or Greater	0	0
Less Than 12 Months	116,827	101,591
Total	116,827	101,591
Gross Unrealized Losses
12 Months or Greater	0	0
Less Than 12 Months	(564)	(119)
Total	$ (564)	$ (119)

Investments - Allowance for Credit Losses (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	$ 0
Allowances for credit losses on securities for which credit losses were not previously recorded	(11,567)
Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets	0
Reductions for securities sold during the year	2,567
Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis	0
(Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period	11,737
Allowance for credit losses, end of year	(322)
Cumulative effect of change in accounting principle
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	(3,059)
Other government
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	0
Allowances for credit losses on securities for which credit losses were not previously recorded	0
Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets	0
Reductions for securities sold during the year	22
Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis	0
(Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period	0
Allowance for credit losses, end of year	0
Other government \| Cumulative effect of change in accounting principle
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	(22)
Corporate
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	0
Allowances for credit losses on securities for which credit losses were not previously recorded	(10,748)
Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets	0
Reductions for securities sold during the year	2,545
Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis	0
(Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period	11,009
Allowance for credit losses, end of year	(181)
Corporate \| Cumulative effect of change in accounting principle
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	(2,987)
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	0
Allowances for credit losses on securities for which credit losses were not previously recorded	(2)
Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets	0
Reductions for securities sold during the year	0
Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis	0
(Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period	2
Allowance for credit losses, end of year	0
Residential mortgage-backed \| Cumulative effect of change in accounting principle
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	0
Commercial mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	0
Allowances for credit losses on securities for which credit losses were not previously recorded	(675)
Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets	0
Reductions for securities sold during the year	0
Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis	0
(Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period	592
Allowance for credit losses, end of year	(133)
Commercial mortgage-backed \| Cumulative effect of change in accounting principle
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	(50)
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	0
Allowances for credit losses on securities for which credit losses were not previously recorded	(142)
Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets	0
Reductions for securities sold during the year	0
Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis	0
(Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period	134
Allowance for credit losses, end of year	(8)
Asset-backed \| Cumulative effect of change in accounting principle
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	$ 0

Investments - Other Than Temporary Impairment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Other than temporary impairment losses, available-for-sale securities	$ 0	$ 0
Available-for-sale securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Credit losses	$ 0

Investments - Equity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt and Equity Securities, FV-NI [Line Items]
Equity investments	$ 846,795	$ 726,721
Publicly traded equity investments
Debt and Equity Securities, FV-NI [Line Items]
Equity investments	260,767	327,875
Exchange-traded funds
Debt and Equity Securities, FV-NI [Line Items]
Equity investments	311,287	133,047
Private equity funds
Debt and Equity Securities, FV-NI [Line Items]
Equity investments	274,741	265,799
AmTrust
Debt and Equity Securities, FV-NI [Line Items]
Indirect investment	$ 230,300	$ 240,100

Investments - Other Investments, at Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Investments [Line Items]
Other investments, at fair value	$ 4,244,034	$ 2,518,031
Valuation lag period	3 months
Net additional subscriptions	$ 975,024	794,613	$ 900,262
Hedge funds
Other Investments [Line Items]
Other investments, at fair value	2,638,339	1,121,904
Fixed income funds
Other Investments [Line Items]
Other investments, at fair value	552,541	481,039
Private equity funds
Other Investments [Line Items]
Other investments, at fair value	363,103	323,496
Private credit funds
Other Investments [Line Items]
Other investments, at fair value	192,319	0
Equity funds
Other Investments [Line Items]
Other investments, at fair value	190,767	410,149
CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	166,523	87,509
CLO equities
Other Investments [Line Items]
Other investments, at fair value	128,083	87,555
Others
Other Investments [Line Items]
Other investments, at fair value	12,359	6,379
Other investments
Other Investments [Line Items]
Unrealized gains	1,336,343	441,702	$ (164,455)
Net additional subscriptions		380,300
Unfunded commitments	975,500
Less than 1 Year
Other Investments [Line Items]
Other investments, at fair value	3,540,382
Less than 1 Year \| Hedge funds
Other Investments [Line Items]
Other investments, at fair value	2,590,164
Less than 1 Year \| Fixed income funds
Other Investments [Line Items]
Other investments, at fair value	537,055
Less than 1 Year \| Private equity funds
Other Investments [Line Items]
Other investments, at fair value	0
Less than 1 Year \| Private credit funds
Other Investments [Line Items]
Other investments, at fair value	0
Less than 1 Year \| Equity funds
Other Investments [Line Items]
Other investments, at fair value	190,767
Less than 1 Year \| CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	94,313
Less than 1 Year \| CLO equities
Other Investments [Line Items]
Other investments, at fair value	128,083
Less than 1 Year \| Others
Other Investments [Line Items]
Other investments, at fair value
1-2 years
Other Investments [Line Items]
Other investments, at fair value	70,991
1-2 years \| Hedge funds
Other Investments [Line Items]
Other investments, at fair value	0
1-2 years \| Fixed income funds
Other Investments [Line Items]
Other investments, at fair value	0
1-2 years \| Private equity funds
Other Investments [Line Items]
Other investments, at fair value	0
1-2 years \| Private credit funds
Other Investments [Line Items]
Other investments, at fair value	9,250
1-2 years \| Equity funds
Other Investments [Line Items]
Other investments, at fair value	0
1-2 years \| CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	61,741
1-2 years \| CLO equities
Other Investments [Line Items]
Other investments, at fair value	0
1-2 years \| Others
Other Investments [Line Items]
Other investments, at fair value
2-3 years
Other Investments [Line Items]
Other investments, at fair value	10,469
2-3 years \| Hedge funds
Other Investments [Line Items]
Other investments, at fair value	0
2-3 years \| Fixed income funds
Other Investments [Line Items]
Other investments, at fair value	0
2-3 years \| Private equity funds
Other Investments [Line Items]
Other investments, at fair value	0
2-3 years \| Private credit funds
Other Investments [Line Items]
Other investments, at fair value
2-3 years \| Equity funds
Other Investments [Line Items]
Other investments, at fair value	0
2-3 years \| CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	10,469
2-3 years \| CLO equities
Other Investments [Line Items]
Other investments, at fair value	0
2-3 years \| Others
Other Investments [Line Items]
Other investments, at fair value
More than 3 years
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years \| Hedge funds
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years \| Fixed income funds
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years \| Private equity funds
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years \| Private credit funds
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years \| Equity funds
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years \| CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years \| CLO equities
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years \| Others
Other Investments [Line Items]
Other investments, at fair value
Not Eligible/ Restricted
Other Investments [Line Items]
Other investments, at fair value	622,192
Not Eligible/ Restricted \| Hedge funds
Other Investments [Line Items]
Other investments, at fair value	48,175	$ 51,800
Not Eligible/ Restricted \| Fixed income funds
Other Investments [Line Items]
Other investments, at fair value	15,486
Not Eligible/ Restricted \| Private equity funds
Other Investments [Line Items]
Other investments, at fair value	363,103
Not Eligible/ Restricted \| Private credit funds
Other Investments [Line Items]
Other investments, at fair value	183,069
Not Eligible/ Restricted \| Equity funds
Other Investments [Line Items]
Other investments, at fair value	0
Not Eligible/ Restricted \| CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	0
Not Eligible/ Restricted \| CLO equities
Other Investments [Line Items]
Other investments, at fair value	0
Not Eligible/ Restricted \| Others
Other Investments [Line Items]
Other investments, at fair value	$ 12,359

Investments - Equity Method Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Ownership %	47.40%	47.40%
Equity method investments	$ 832,295	$ 326,277
Citco \| CTCO Holdings Limited
Schedule of Equity Method Investments [Line Items]
Ownership interest held by noncontrolling owners	6.20%
Convertible Preferred Stock \| Citco \| CTCO Holdings Limited
Schedule of Equity Method Investments [Line Items]
Ownership interest held by noncontrolling owners	15.40%
Enhanzed Re
Schedule of Equity Method Investments [Line Items]
Ownership %	47.40%	47.40%
Equity method investments	$ 330,289	$ 182,856
Citco
Schedule of Equity Method Investments [Line Items]
Ownership %		31.90%
Equity method investments	$ 53,022	$ 51,742
Citco \| Ordinary Shares
Schedule of Equity Method Investments [Line Items]
Ownership %	31.90%
Monument Re
Schedule of Equity Method Investments [Line Items]
Ownership %	23.00%	23.50%
Equity method investments	$ 193,716	$ 60,598
Monument Re \| Ordinary Shares
Schedule of Equity Method Investments [Line Items]
Ownership %	20.00%	20.00%
Clear Spring
Schedule of Equity Method Investments [Line Items]
Ownership %	0.00%	20.00%
Equity method investments	$ 0	$ 10,645
StarStone US
Schedule of Equity Method Investments [Line Items]
Ownership %	25.20%	0.00%
Equity method investments	$ 235,000	$ 0
Other
Schedule of Equity Method Investments [Line Items]
Ownership %	27.00%	30.00%
Equity method investments	$ 20,268	$ 20,436
Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Unfunded commitments	$ 68,700

Investments - Funds Held (Details) - USD ($) $ in Thousands	12 Months Ended
Investments - Funds Held (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Funds Held, Directly Managed [Abstract]
Funds held - directly managed	$ 1,074,890	$ 1,187,552
Net unrealized gains (losses):
Funds held by reinsured companies	635,819	475,732
AXA Group
Net unrealized gains (losses):
Reinsurance premium consideration	204,200
Funds Held - Directly Managed
Funds Held, Directly Managed [Abstract]
Fixed maturity investments, trading	1,060,263	1,173,345
Cash and cash equivalents	9,067	10,296
Other assets	5,560	3,911
Funds held - directly managed	1,074,890	1,187,552
Funds Held, Directly Managed, Fixed-Maturity Investment Components [Abstract]
Fixed maturity investments, at amortized cost	966,341	1,126,053
Net unrealized gains (losses):
Change in fair value - fair value option accounting	9,693	5,438
Change in fair value - embedded derivative accounting	84,229	41,854
Fixed maturity investments, trading	1,060,263	1,173,345
Funds held - Directly Managed - Fair Value Option
Funds Held, Directly Managed [Abstract]
Fixed maturity investments, trading	116,631	191,297
Funds Held, Directly Managed, Fixed-Maturity Investment Components [Abstract]
Fixed maturity investments, at amortized cost	106,938	185,859
Net unrealized gains (losses):
Change in fair value - fair value option accounting	9,693	5,438
Change in fair value - embedded derivative accounting	0	0
Fixed maturity investments, trading	116,631	191,297
Funds held - Directly Managed - Variable Return
Funds Held, Directly Managed [Abstract]
Fixed maturity investments, trading	943,632	982,048
Funds Held, Directly Managed, Fixed-Maturity Investment Components [Abstract]
Fixed maturity investments, at amortized cost	859,403	940,194
Net unrealized gains (losses):
Change in fair value - fair value option accounting	0	0
Change in fair value - embedded derivative accounting	84,229	41,854
Fixed maturity investments, trading	$ 943,632	$ 982,048

Investments - Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Investment Income [Line Items]
Gross investment income									$ 318,707	$ 322,711	$ 270,779
Investment expenses									(15,890)	(14,440)	(9,081)
Net investment income	$ 61,530	$ 72,130	$ 94,443	$ 74,714	$ 76,847	$ 81,502	$ 74,271	$ 75,651	302,817	308,271	261,698
Fixed maturity investments, trading
Net Investment Income [Line Items]
Gross investment income									198,988	217,886	178,213
Short-term investments and cash and cash equivalents
Net Investment Income [Line Items]
Gross investment income									4,843	15,609	11,692
Funds held
Net Investment Income [Line Items]
Gross investment income									33,920	22,580	11,640
Funds held – directly managed
Net Investment Income [Line Items]
Gross investment income									34,563	38,173	37,623
Investment income from fixed maturities and cash and cash equivalents
Net Investment Income [Line Items]
Gross investment income									272,314	294,248	239,168
Equity investments
Net Investment Income [Line Items]
Gross investment income									19,240	16,671	5,397
Other investments
Net Investment Income [Line Items]
Gross investment income									27,153	11,792	26,214
Investment income from equities and other investments
Net Investment Income [Line Items]
Gross investment income									$ 46,393	$ 28,463	$ 31,611

Investments - Net Realized and Unrealized Gains (Losses) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, AFS									$ 26,313	$ 4,844	$ 27
Gross realized losses on fixed maturity securities, AFS									(7,801)	(905)	(90)
Decrease in allowance for expected credit losses on fixed maturity securities, AFS									(509)	0	0
Net realized investment gains on investment derivatives									144	0	0
Total net realized gains (losses) on sale									178,851	86,071	(27,395)
Net unrealized gains (losses):
Investment derivatives									718	(349)	0
Total net unrealized gains (losses)									1,463,168	925,895	(380,137)
Net realized and unrealized gains (losses)	$ 803,467	$ 500,005	$ 967,608	$ (629,061)	$ 153,477	$ 145,060	$ 260,669	$ 452,760	1,642,019	1,011,966	(407,532)
Proceeds from sale of available from sale securities									2,000,000	302,900	11,400
Fixed maturity investments
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, AFS									26,313	4,844	27
Gross realized losses on fixed maturity securities, AFS									(7,801)	(905)	(90)
Decrease in allowance for expected credit losses on fixed maturity securities, AFS									170	0	0
Net realized gains (losses) on trading securities									126,945	81,011	(27,408)
Net unrealized gains (losses):
Fixed maturity securities, trading									101,022	341,130
Fixed maturity securities, trading											(159,594)
Funds Held - Directly Managed
Net realized gains (losses) on sale:
Net realized gains (losses) on trading securities									8,798	1,495	(3,940)
Net unrealized gains (losses):
Fixed maturity securities, trading									50,837	88,053
Fixed maturity securities, trading											(46,257)
Equity investments
Net realized gains (losses) on sale:
Net realized gains (losses) on equity investments									24,282	(374)	4,016
Net unrealized gains (losses):
Equity investments									(25,752)	55,359	(9,831)
Other investments
Net unrealized gains (losses):
Other investments									1,336,343	$ 441,702	$ (164,455)
Other investments \| Hedge Fund Managed By AnglePoint
Net unrealized gains (losses):
Total net unrealized gains (losses)									$ 1,200,000

Investments - Reconciliation to Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Gross realized gains on fixed maturity securities, AFS	$ 26,313	$ 4,844	$ 27
Gross realized losses on fixed maturity securities, AFS	(7,801)	(905)	(90)
Tax effect	(1,623)	0	0
Total reclassification adjustment for net realized gains (losses) included in net earnings	18,033	3,894	(63)
Credit recoveries (losses) on fixed maturity securities, AFS	509	0	0
Discontinued Operations
Debt Securities, Available-for-sale [Line Items]
Gross realized gains on fixed maturity securities, AFS	1,374	12	0
Gross realized losses on fixed maturity securities, AFS	(120)	(57)	0
Tax effect	(110)	0	0
Credit recoveries (losses) on fixed maturity securities, AFS	329	0	0
Tax effect	7	0	0
Continuing Operations
Debt Securities, Available-for-sale [Line Items]
Credit recoveries (losses) on fixed maturity securities, AFS	170	0	0
Tax effect	$ 3	$ 0	$ 0

Investments - Restricted Assets (Details) $ in Thousands	Dec. 31, 2020 USD ($) syndicate	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Investments, Debt and Equity Securities [Abstract]
Restricted cash and cash equivalents	$ 471,964	$ 346,877	$ 366,187
Line of Credit Facility [Line Items]
Collateral in trust for third party agreements	4,924,866	4,103,847
Assets on deposit with regulatory authorities	131,283	309,659
Funds at Lloyd's	260,914	639,316
Restricted assets, total	$ 5,421,690	5,185,492
Number of syndicates \| syndicate	3
Asset Pledged as Collateral
Line of Credit Facility [Line Items]
Collateral for secured letter of credit facilities	$ 104,627	$ 132,670

Derivatives and Hedging Instruments - Foreign Currency Hedging (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effect of Net Investment Hedge
Cumulative currency translation adjustment	$ (2,069)	$ (2,428)	$ (202)
Net Investment Hedging
Effect of Net Investment Hedge
Cumulative currency translation adjustment			3,100
Designated as Hedging Instrument \| Currency forward contracts
Gross Notional Amounts and Estimated Fair Values
Gross Notional Amount	603,691	495,291
Assets	1,169	642
Liabilities	28,947	11,452
Effect of Net Investment Hedge
Amount of Gains (Losses) Deferred in AOCI	(30,275)	(15,328)	4,438
Designated as Hedging Instrument \| Currency forward contracts \| Australia, Dollars
Gross Notional Amounts and Estimated Fair Values
Gross Notional Amount	73,852	64,620
Assets	13	52
Liabilities	5,060	2,033
Effect of Net Investment Hedge
Amount of Gains (Losses) Deferred in AOCI	(6,792)	(722)	3,438
Designated as Hedging Instrument \| Currency forward contracts \| Euro Member Countries, Euro
Gross Notional Amounts and Estimated Fair Values
Gross Notional Amount	217,168	112,284
Assets	205	246
Liabilities	8,889	1,635
Effect of Net Investment Hedge
Amount of Gains (Losses) Deferred in AOCI	(15,026)	1,817	1,000
Designated as Hedging Instrument \| Currency forward contracts \| United Kingdom, Pounds
Gross Notional Amounts and Estimated Fair Values
Gross Notional Amount	312,671	318,387
Assets	951	344
Liabilities	14,998	7,784
Effect of Net Investment Hedge
Amount of Gains (Losses) Deferred in AOCI	$ (8,457)	$ (16,423)	$ 0

Derivatives and Hedging Instruments - Foreign Currency Forward Contracts (Details) - Not Designated as Hedging Instrument - Currency forward contracts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Gross Notional Amount	$ 139,334	$ 153,563
Assets	2,835	1,369
Liabilities	5,056	4,106
Gains (losses) on non-qualifying hedges charged to earnings	(2,954)	13,207	$ 31,643
Australia, Dollars
Derivative [Line Items]
Gross Notional Amount	28,848	913
Assets	882	839
Liabilities	2,847	892
Gains (losses) on non-qualifying hedges charged to earnings	(2,388)	1,523	4,958
Canada, Dollars
Derivative [Line Items]
Gross Notional Amount	64,224	66,266
Assets	10	10
Liabilities	1,764	1,482
Gains (losses) on non-qualifying hedges charged to earnings	(879)	(2,079)	9,311
Euro Member Countries, Euro
Derivative [Line Items]
Gross Notional Amount	43,531	74,444
Assets	1,782	507
Liabilities	41	1,440
Gains (losses) on non-qualifying hedges charged to earnings	1,871	1,759	2,296
United Kingdom, Pounds
Derivative [Line Items]
Gross Notional Amount	2,731	11,940
Assets	161	13
Liabilities	404	292
Gains (losses) on non-qualifying hedges charged to earnings	$ (1,558)	$ 12,004	$ 15,078

Derivatives and Hedging Instruments - Investments in Call Options (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Unrealized gains (losses) in net earnings (less than)	$ 718	$ (349)	$ 0
Not Designated as Hedging Instrument \| Call options on equity
Derivative [Line Items]
Unrealized gains (losses) in net earnings (less than)	$ (100)	500	(9,400)
Gross Notional Amount			$ 10,000
Fair value (less than)		$ 100

Derivatives and Hedging Instruments - Forward Interest Rate Swaps (Details) $ in Thousands, $ in Millions	12 Months Ended			15 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Apr. 07, 2020 USD ($)	Dec. 31, 2019 AUD ($)
Derivative [Line Items]
Unrealized gains (losses) in net earnings	$ 718	$ (349)	$ 0
Interest Rate Swap
Derivative [Line Items]
Notional amount					$ 120.0
Unrealized gains (losses) in net earnings	$ 800
Realized gain				$ 500
Carrying value \| Interest Rate Swap
Derivative [Line Items]
Derivative instruments		$ 300

Derivatives and Hedging Instruments - Credit Default Swaps, Futures and Currency Forward Contracts (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Derivative [Line Items]
Net gains (losses)	$ 626
Credit default swaps
Derivative [Line Items]
Net gains (losses)	181
Futures contracts
Derivative [Line Items]
Net gains (losses)	(127)
Futures contracts \| Long positions
Derivative [Line Items]
Gross Notional Amount	34,502
Assets	32
Liabilities	5
Futures contracts \| Short positions
Derivative [Line Items]
Gross Notional Amount	(32,316)
Assets	6
Liabilities	121
Currency forward contracts
Derivative [Line Items]
Net gains (losses)	572
Currency forward contracts \| Long positions \| United States of America, Dollars
Derivative [Line Items]
Gross Notional Amount	1,428
Assets	0
Liabilities	13
Currency forward contracts \| Long positions \| United Kingdom, Pounds
Derivative [Line Items]
Gross Notional Amount	1,278
Assets	19
Liabilities	0
Currency forward contracts \| Short positions \| United States of America, Dollars
Derivative [Line Items]
Gross Notional Amount	(3,233)
Assets	60
Liabilities	0
Currency forward contracts \| Short positions \| United Kingdom, Pounds
Derivative [Line Items]
Gross Notional Amount	(4,418)
Assets	12
Liabilities	0
Credit default swaps, futures contracts and currency forward contracts
Derivative [Line Items]
Gross Notional Amount	(2,759)
Assets	129
Liabilities	$ 139

Reinsurance Balances Recoverable on Paid and Unpaid Losses - Summary of Reinsurance Reserves Recoverable (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effects of Reinsurance [Line Items]
Outstanding losses	$ 1,201,869	$ 1,245,435
IBNR	647,843	785,530
ULAE	16,688
Fair value adjustments - acquired companies	(15,353)	(15,255)
Fair value adjustments - fair value option	(21,427)	(88,086)
Total reinsurance reserves recoverable	1,829,620	1,927,624	$ 1,708,272	$ 1,693,028
Paid losses recoverable	259,543	253,510
Total	2,089,163	2,181,134
Reinsurance balances recoverable on paid and unpaid losses	1,568,333	1,485,616
Reinsurance balances recoverable on paid and unpaid losses - fair value option	520,830	695,518
Non-life Run-off
Effects of Reinsurance [Line Items]
Outstanding losses	938,231	972,293
IBNR	508,082	673,059
ULAE	16,688
Fair value adjustments - acquired companies	(14,014)	(13,652)
Fair value adjustments - fair value option	(21,427)	(88,086)
Total reinsurance reserves recoverable	1,427,560	1,543,614	1,366,123	1,377,485
Paid losses recoverable	172,309	181,375
Total	1,599,869	1,724,989
Reinsurance balances recoverable on paid and unpaid losses	1,079,039	1,029,471
Reinsurance balances recoverable on paid and unpaid losses - fair value option	520,830	695,518
Atrium
Effects of Reinsurance [Line Items]
Outstanding losses		9,011
IBNR		19,286
Fair value adjustments - acquired companies		519
Fair value adjustments - fair value option		0
Total reinsurance reserves recoverable	0	28,816	38,768	40,531
Paid losses recoverable		1,541
Total		30,357
Reinsurance balances recoverable on paid and unpaid losses		30,357
Reinsurance balances recoverable on paid and unpaid losses - fair value option		0
StarStone
Effects of Reinsurance [Line Items]
Outstanding losses	263,638	264,131
IBNR	139,761	93,185
ULAE	0
Fair value adjustments - acquired companies	(1,339)	(2,122)
Fair value adjustments - fair value option	0	0
Total reinsurance reserves recoverable	402,060	355,194	$ 303,381	$ 275,012
Paid losses recoverable	87,234	70,594
Total	489,294	425,788
Reinsurance balances recoverable on paid and unpaid losses	489,294	425,788
Reinsurance balances recoverable on paid and unpaid losses - fair value option	$ 0	$ 0

Reinsurance Balances Recoverable on Paid and Unpaid Losses - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 2,089,163	$ 2,181,134
(Decrease) in reinsurance recoverable	(52,027)	$ 316,440	$ 289,295
Non-Life Run-Off
Effects of Reinsurance [Line Items]
(Decrease) in reinsurance recoverable	$ (92,000)

Reinsurance Balances Recoverable on Paid and Unpaid Losses - Top Ten Reinsurers (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) reinsurer	Dec. 31, 2019 USD ($) reinsurer
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 2,089,163	$ 2,181,134
Reinsurer concentration risk \| Top 10 reinsurers
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	1,364,593	1,471,604
Reinsurance balances recoverable \| Reinsurer concentration risk
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 2,089,163	$ 2,181,134
% of Total	100.00%	100.00%
Reinsurance balances recoverable \| Reinsurer concentration risk \| Top Ten Reinsurers, Rated A Minus Or Higher
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 863,819	$ 1,199,479
Number of external reinsurers \| reinsurer	7	8
Reinsurance balances recoverable \| Reinsurer concentration risk \| Top Ten Reinsurers, Non-Rated Reinsurers
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 500,774	$ 272,125
Number of external reinsurers \| reinsurer	3	2
Reinsurance balances recoverable \| Reinsurer concentration risk \| Top 10 reinsurers
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 1,364,593	$ 1,471,604
% of Total	65.30%	67.40%
Reinsurance balances recoverable \| Reinsurer concentration risk \| Other Reinsurers' Balances Greater Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 697,602	$ 688,732
% of Total	33.40%	31.60%
Reinsurance balances recoverable \| Reinsurer concentration risk \| Other Reinsurers' Balances Less Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 26,968	$ 20,798
% of Total	1.30%	1.00%
Reinsurance balances recoverable \| Reinsurer concentration risk \| Top Ten Reinsurers, Non-Rated Reinsurers, US State Backed
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 229,400	$ 190,800
Reinsurance balances recoverable \| Reinsurer concentration risk \| Top Ten Reinsurers, Non-Rated Reinsurers, Provided Security
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	73,800	81,400
Reinsurance balances recoverable \| Reinsurer concentration risk \| Top Ten Reinsurers, Non-Rated Reinsurers, Provided Security, Reinsurer Two
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	208,400
Non-life Run-off
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	1,599,869	1,724,989
Non-life Run-off \| Reinsurance balances recoverable \| Reinsurer concentration risk
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	1,599,869	1,724,989
Non-life Run-off \| Reinsurance balances recoverable \| Reinsurer concentration risk \| Top 10 reinsurers
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	1,036,676	1,154,110
Non-life Run-off \| Reinsurance balances recoverable \| Reinsurer concentration risk \| Other Reinsurers' Balances Greater Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	539,428	551,636
Non-life Run-off \| Reinsurance balances recoverable \| Reinsurer concentration risk \| Other Reinsurers' Balances Less Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	23,765	19,243
Atrium
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses		30,357
Atrium \| Reinsurance balances recoverable \| Reinsurer concentration risk
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses		30,357
Atrium \| Reinsurance balances recoverable \| Reinsurer concentration risk \| Top 10 reinsurers
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses		22,051
Atrium \| Reinsurance balances recoverable \| Reinsurer concentration risk \| Other Reinsurers' Balances Greater Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses		7,761
Atrium \| Reinsurance balances recoverable \| Reinsurer concentration risk \| Other Reinsurers' Balances Less Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses		545
StarStone
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	489,294	425,788
StarStone \| Reinsurance balances recoverable \| Reinsurer concentration risk
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	489,294	425,788
StarStone \| Reinsurance balances recoverable \| Reinsurer concentration risk \| Top 10 reinsurers
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	327,917	295,443
StarStone \| Reinsurance balances recoverable \| Reinsurer concentration risk \| Other Reinsurers' Balances Greater Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	158,174	129,335
StarStone \| Reinsurance balances recoverable \| Reinsurer concentration risk \| Other Reinsurers' Balances Less Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	3,203	1,010
Equity method investee \| Reinsurer concentration risk \| Hannover Ruck SE
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	0	259,077
Equity method investee \| Reinsurer concentration risk \| Lloyd's Syndicate
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	331,118	396,246
Equity method investee \| Reinsurer concentration risk \| Michigan Catastrophic Claims Associations
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 229,374	$ 0

Reinsurance Balances Recoverable on Paid and Unpaid Losses - Provisions for Uncollectible Reinsurance Balances Recoverable by Rating of Reinsurer (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effects of Reinsurance [Line Items]
Gross	$ 2,226,285	$ 2,328,773
Allowance for estimated uncollectible reinsurance	137,122	147,639	$ 156,732
Total	$ 2,089,163	$ 2,181,134
Provisions as a % of Gross	6.20%	6.30%
Reinsurers rated A- or above
Effects of Reinsurance [Line Items]
Gross	$ 1,464,529	$ 1,731,270
Allowance for estimated uncollectible reinsurance	60,801	43,427
Total	$ 1,403,728	$ 1,687,843
Provisions as a % of Gross	4.20%	2.50%
Secured \| Reinsurers Rated Below A-
Effects of Reinsurance [Line Items]
Gross	$ 608,999	$ 463,840
Allowance for estimated uncollectible reinsurance	0	0
Total	$ 608,999	$ 463,840
Provisions as a % of Gross	0.00%	0.00%
Unsecured \| Reinsurers Rated Below A-
Effects of Reinsurance [Line Items]
Gross	$ 152,757	$ 133,663
Allowance for estimated uncollectible reinsurance	76,321	104,212
Total	$ 76,436	$ 29,451
Provisions as a % of Gross	50.00%	78.00%

Reinsurance Balances Recoverable on Paid and Unpaid Losses - Allowance For Credit Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Allowance for estimated uncollectible reinsurance, beginning of year	$ 147,639	$ 156,732
Effect of exchange rate movement	700	(887)
Current period change in the allowance	(381)	2,077
Write-offs charged against the allowance	(9,625)	(9,871)
Recoveries collected	(1,016)	(412)
Allowance for estimated uncollectible reinsurance, end of year	137,122	147,639
Cumulative effect of change in accounting principle
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Allowance for estimated uncollectible reinsurance, beginning of year	$ (195)	0
Allowance for estimated uncollectible reinsurance, end of year		$ (195)

Deferred Charge Assets and Deferred Gain Liabilities (Deferred Charge Assets) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning carrying value	$ 272,462,000	$ 86,585,000	$ 80,192,000
Recorded during the year	11,746,000	224,504,000	20,174,000
Amortization	(45,606,000)	(38,627,000)	(13,781,000)
Ending carrying value	238,602,000	$ 272,462,000	$ 86,585,000
Impairment	$ 0

Amount of amortization expense (reversal of expense) for deferred policy acquisition costs.

Deferred Charge Assets and Deferred Gain Liabilities (Deferred Gain Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Movement Analysis Of Deferred Gain Liabilities [Roll Forward]
Beginning carrying value	$ 12,875	$ 0
Recorded during the year	9,365	13,758
Amortization	(2,360)	(883)
Ending carrying value	$ 19,880	$ 12,875

Losses and Loss Adjustment Expenses - Total Losses and Loss Adjustment Expense Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	$ 5,127,849	$ 5,249,565
IBNR	5,277,503	4,651,649
Fair value adjustments - acquired companies	(143,183)	(167,511)
Fair value adjustments - fair value option	(54,589)	(217,933)
ULAE	385,702	352,634
Total	10,593,282	9,868,404	$ 9,048,796	$ 7,100,488
Loss and loss adjustment expenses	8,140,362	7,247,282
Loss and loss adjustment expenses, at fair value	2,452,920	2,621,122
Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	4,440,425	4,407,082
IBNR	4,641,500	3,945,407
Fair value adjustments - acquired companies	(142,854)	(170,689)
Fair value adjustments - fair value option	(54,589)	(217,933)
ULAE	333,913	331,494
Total	9,235,082	8,295,361	7,540,662	5,949,472
Atrium
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses		89,141
IBNR		136,543
Fair value adjustments - acquired companies		3,700
ULAE		2,288
Total	0	231,672	241,284	240,873
StarStone
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	677,220	743,830
IBNR	615,963	556,134
Fair value adjustments - acquired companies	(329)	(522)
ULAE	35,101	18,852
Total	1,327,956	1,318,294	$ 1,247,989	$ 910,143
Operating Segments \| Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	4,440,425	4,407,082
IBNR	4,641,500	3,945,407
Fair value adjustments - acquired companies	(142,854)	(170,689)
Fair value adjustments - fair value option	(54,589)	(217,933)
ULAE	350,600	331,494
Total	9,235,082	8,295,361
Loss and loss adjustment expenses	6,782,162	5,674,239
Loss and loss adjustment expenses, at fair value	2,452,920	2,621,122
Operating Segments \| Atrium
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses		89,141
IBNR		136,543
Fair value adjustments - acquired companies		3,700
Fair value adjustments - fair value option		0
ULAE		2,288
Total		231,672
Loss and loss adjustment expenses		231,672
Loss and loss adjustment expenses, at fair value		0
Operating Segments \| StarStone
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	677,220	743,830
IBNR	615,963	556,134
Fair value adjustments - acquired companies	(329)	(522)
Fair value adjustments - fair value option	0	0
ULAE	35,102	18,852
Total	1,327,956	1,318,294
Loss and loss adjustment expenses	1,327,956	1,318,294
Loss and loss adjustment expenses, at fair value	0	0
Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	10,204	9,512
IBNR	20,040	13,565
Fair value adjustments - acquired companies	0	0
Fair value adjustments - fair value option	0	0
ULAE	0	0
Total	30,244	23,077
Loss and loss adjustment expenses	30,244	23,077
Loss and loss adjustment expenses, at fair value	$ 0	$ 0

Losses and Loss Adjustment Expenses - Reconciliation of Beginning and Ending Reserves for Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as of January 1				$ 9,868,404				$ 9,048,796	$ 9,868,404	$ 9,048,796	$ 7,100,488
Less: reinsurance reserves recoverable				1,927,624				1,708,272	1,927,624	1,708,272	1,693,028
Less: net deferred charge assets and gain liabilities on retroactive reinsurance				259,587				86,585	259,587	86,585	80,192
Net balance as of January 1				7,681,193				7,253,939	7,681,193	7,253,939
Net incurred losses and LAE:
Current period									405,178	580,074	533,081
Prior periods									10,748	34,105	(209,359)
Total net incurred losses and LAE	$ 76,248	$ 109,686	$ 186,692	43,300	$ 48,068	$ 163,258	$ 146,554	256,299	415,926	614,179	323,722
Net paid losses:
Current period									(71,989)	(179,461)	(176,172)
Prior periods									(1,413,500)	(1,609,009)	(1,158,614)
Total net paid losses									(1,485,489)	(1,788,470)	(1,334,786)
Effect of exchange rate movement									119,663	47,812	(145,243)
Acquired on purchase of subsidiaries									0	686	1,310,874
Assumed business									2,186,024	1,586,307	1,772,104
Ceded business									(154,926)	(33,260)	0
Reclassification to assets and liabilities held-for-sale									(216,808)	0	0
Net balance as of December 31	8,544,940				7,681,193				8,544,940	7,681,193	7,253,939
Plus: reinsurance reserves recoverable	1,829,620				1,927,624				1,829,620	1,927,624	1,708,272
Plus: net deferred charge assets and gain liabilities on retroactive reinsurance	218,722				259,587				218,722	259,587	86,585
Balance as of December 31	10,593,282				9,868,404				10,593,282	9,868,404	9,048,796
Cumulative effect of change in accounting principle
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances					643					643	0	$ 0
Cumulative effect of change in accounting principle \| Discontinued operations, held-for-sale \| StarStone US
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances					400					400
Cumulative effect of change in accounting principle, adjusted balance
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net balance as of January 1				7,680,550				7,253,939	7,680,550	7,253,939	5,327,268
Net paid losses:
Net balance as of December 31					7,680,550					7,680,550	7,253,939
Non-life Run-off
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as of January 1				8,295,361				7,540,662	8,295,361	7,540,662	5,949,472
Less: reinsurance reserves recoverable				1,543,614				1,366,123	1,543,614	1,366,123	1,377,485
Less: net deferred charge assets and gain liabilities on retroactive reinsurance				259,587				86,585	259,587	86,585	80,192
Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances	(48,443)								(48,443)
Net balance as of January 1				6,492,160				6,087,954	6,492,160	6,087,954
Net incurred losses and LAE:
Current period									30,165	123,559	12,451
Prior periods									14,830	(71,934)	(318,518)
Total net incurred losses and LAE									44,995	51,625	(306,067)
Net paid losses:
Current period									(9,990)	(64,820)	(5)
Prior periods									(1,064,911)	(1,182,804)	(838,812)
Total net paid losses									(1,074,901)	(1,247,624)	(838,817)
Effect of exchange rate movement									94,745	46,472	(132,632)
Acquired on purchase of subsidiaries									0	686	1,111,839
Assumed business									2,186,024	1,586,307	1,761,836
Ceded business									(154,926)	(33,260)	0
Net balance as of December 31	7,588,800				6,492,160				7,588,800	6,492,160	6,087,954
Plus: reinsurance reserves recoverable	1,427,560				1,543,614				1,427,560	1,543,614	1,366,123
Plus: net deferred charge assets and gain liabilities on retroactive reinsurance	218,722				259,587				218,722	259,587	86,585
Balance as of December 31	9,235,082				8,295,361				9,235,082	8,295,361	7,540,662
Non-life Run-off \| Cumulative effect of change in accounting principle
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances					703					703	0	0
Non-life Run-off \| Cumulative effect of change in accounting principle, adjusted balance
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net balance as of January 1				6,492,863				6,087,954	6,492,863	6,087,954	4,491,795
Net paid losses:
Net balance as of December 31					6,492,863					6,492,863	6,087,954
Atrium
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as of January 1				231,672				241,284	231,672	241,284	240,873
Less: reinsurance reserves recoverable				28,816				38,768	28,816	38,768	40,531
Net balance as of January 1				202,856				202,516	202,856	202,516
Net incurred losses and LAE:
Current period									93,471	85,027	83,627
Prior periods									(6,245)	(7,751)	(13,817)
Total net incurred losses and LAE									87,226	77,276	69,810
Net paid losses:
Current period									(33,724)	(34,617)	(35,537)
Prior periods									(40,196)	(43,572)	(28,969)
Total net paid losses									(73,920)	(78,189)	(64,506)
Effect of exchange rate movement									1,497	1,253	(3,130)
Reclassification to assets and liabilities held-for-sale									(216,808)	0	0
Net balance as of December 31	0				202,856				0	202,856	202,516
Plus: reinsurance reserves recoverable	0				28,816				0	28,816	38,768
Balance as of December 31	0				231,672				0	231,672	241,284
Atrium \| Cumulative effect of change in accounting principle
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances					851					851	0	0
Atrium \| Cumulative effect of change in accounting principle, adjusted balance
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net balance as of January 1				202,005				202,516	202,005	202,516	200,342
Net paid losses:
Net balance as of December 31					202,005					202,005	202,516
StarStone
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as of January 1				1,318,294				1,247,989	1,318,294	1,247,989	910,143
Less: reinsurance reserves recoverable				355,194				303,381	355,194	303,381	275,012
Net balance as of January 1				963,100				944,608	963,100	944,608
Net incurred losses and LAE:
Current period									263,562	354,884	422,191
Prior periods									3,176	114,356	120,889
Total net incurred losses and LAE									266,738	469,240	543,080
Net paid losses:
Current period									(26,831)	(75,458)	(137,390)
Prior periods									(300,037)	(375,377)	(289,981)
Total net paid losses									(326,868)	(450,835)	(427,371)
Effect of exchange rate movement									23,421	87	(9,481)
Acquired on purchase of subsidiaries									0	0	192,981
Assumed business									0	0	10,268
Ceded business									0	0	0
Net balance as of December 31	925,896				963,100				925,896	963,100	944,608
Plus: reinsurance reserves recoverable	402,060				355,194				402,060	355,194	303,381
Balance as of December 31	$ 1,327,956				1,318,294				1,327,956	1,318,294	1,247,989
StarStone \| Cumulative effect of change in accounting principle
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances					495					495	0	$ 0
StarStone \| Cumulative effect of change in accounting principle, adjusted balance
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net balance as of January 1				$ 962,605				$ 944,608	$ 962,605	944,608	635,131
Net paid losses:
Net balance as of December 31					$ 962,605					$ 962,605	$ 944,608

Losses and Loss Adjustment Expenses - Net Incurred Losses and Loss Adjustment Expense Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Prior Period
Net losses paid, prior period									$ 1,413,500	$ 1,609,009	$ 1,158,614
Prior periods									10,748	34,105	(209,359)
Current Period
Net losses paid, current period									71,989	179,461	176,172
Net incurred losses and LAE, current period									405,178	580,074	533,081
Total
Net losses paid									1,485,489	1,788,470	1,334,786
Net change in case and LAE reserves									(540,187)	(528,583)	(472,420)
Net change in IBNR reserves									(687,624)	(794,704)	(506,794)
Increase (reduction) in estimates of net ultimate losses									257,678	465,183	355,572
Increase (reduction) in provisions for unallocated LAE									(31,550)	(56,502)	(59,788)
Amortization of deferred charge assets and deferred gain liabilities									43,246	37,744	13,781
Amortization of fair value adjustments									27,506	50,573	7,493
Changes in fair value - fair value option									119,046	117,181	6,664
Total net incurred losses and LAE	$ 76,248	$ 109,686	$ 186,692	$ 43,300	$ 48,068	$ 163,258	$ 146,554	$ 256,299	415,926	614,179	323,722
Non-life Run-off
Prior Period
Net losses paid, prior period									1,064,911	1,182,804	838,812
Net change in case and LAE reserves, prior period									(449,610)	(553,996)	(552,124)
Net change in IBNR reserves, prior period									(742,417)	(847,893)	(573,127)
Increase (reduction) in estimates of net ultimate losses, prior period									(127,116)	(219,085)	(286,439)
Increase (reduction) in provisions for unallocated LAE, prior period									(48,407)	(57,844)	(65,401)
Amortization of deferred charge assets and deferred gain liabilities, prior period									42,640	37,744	13,781
Amortization of fair value adjustments, prior period									28,667	50,070	12,877
Changes in fair value - fair value option, prior period									119,046	117,181	6,664
Prior periods									14,830	(71,934)	(318,518)
Current Period
Net losses paid, current period									9,990	64,820	5
Net change in case and LAE reserves, current period									(3,470)	23,105	4,704
Net change in IBNR reserves, current period									24,003	35,194	7,742
Increase (reduction) in estimates of net ultimate losses, current period									30,523	123,119	12,451
Increase (reduction) in provisions for unallocated LAE, current period									(358)	440	0
Amortization of deferred charge assets and deferred gain liabilities, current period									0	0	0
Amortization of fair value adjustments, current period									0	0	0
Changes in fair value - fair value option, current period									0	0	0
Net incurred losses and LAE, current period									30,165	123,559	12,451
Total
Net losses paid									1,074,901	1,247,624	838,817
Net change in case and LAE reserves									(453,080)	(530,891)	(547,420)
Net change in IBNR reserves									(718,414)	(812,699)	(565,385)
Increase (reduction) in estimates of net ultimate losses									(96,593)	(95,966)	(273,988)
Increase (reduction) in provisions for unallocated LAE									(48,765)	(57,404)	(65,401)
Amortization of deferred charge assets and deferred gain liabilities									42,640	37,744	13,781
Amortization of fair value adjustments									28,667	50,070	12,877
Changes in fair value - fair value option									119,046	117,181	6,664
Total net incurred losses and LAE									44,995	51,625	(306,067)
Atrium
Prior Period
Net losses paid, prior period									40,196	43,572	28,969
Net change in case and LAE reserves, prior period									(14,145)	(13,278)	(10,161)
Net change in IBNR reserves, prior period									(31,773)	(38,380)	(27,507)
Increase (reduction) in estimates of net ultimate losses, prior period									(5,722)	(8,086)	(8,699)
Increase (reduction) in provisions for unallocated LAE, prior period									48	0	0
Amortization of fair value adjustments, prior period									(571)	335	(5,118)
Prior periods									(6,245)	(7,751)	(13,817)
Current Period
Net losses paid, current period									33,724	34,617	35,537
Net change in case and LAE reserves, current period									21,390	16,812	16,492
Net change in IBNR reserves, current period									38,434	33,598	31,598
Increase (reduction) in estimates of net ultimate losses, current period									93,548	85,027	83,627
Increase (reduction) in provisions for unallocated LAE, current period									(77)	0	0
Amortization of fair value adjustments, current period									0	0	0
Net incurred losses and LAE, current period									93,471	85,027	83,627
Total
Net losses paid									73,920	78,189	64,506
Net change in case and LAE reserves									7,245	3,534	6,331
Net change in IBNR reserves									6,661	(4,782)	4,091
Increase (reduction) in estimates of net ultimate losses									87,826	76,941	74,928
Increase (reduction) in provisions for unallocated LAE									(29)	0	0
Amortization of deferred charge assets and deferred gain liabilities									0	0	0
Amortization of fair value adjustments									(571)	335	(5,118)
Changes in fair value - fair value option									0	0	0
Total net incurred losses and LAE									87,226	77,276	69,810
StarStone
Prior Period
Net losses paid, prior period									300,037	375,377	289,981
Net change in case and LAE reserves, prior period									(130,502)	(95,183)	(77,821)
Net change in IBNR reserves, prior period									(165,909)	(163,340)	(87,963)
Increase (reduction) in estimates of net ultimate losses, prior period									3,626	116,854	124,197
Increase (reduction) in provisions for unallocated LAE, prior period									(466)	(2,666)	(3,042)
Amortization of deferred charge assets and deferred gain liabilities, prior period									606	0	0
Amortization of fair value adjustments, prior period									(590)	168	(266)
Prior periods									3,176	114,356	120,889
Current Period
Net losses paid, current period									26,831	75,458	137,390
Net change in case and LAE reserves, current period									35,458	90,497	141,682
Net change in IBNR reserves, current period									183,563	185,361	134,464
Increase (reduction) in estimates of net ultimate losses, current period									245,852	351,316	413,536
Increase (reduction) in provisions for unallocated LAE, current period									17,710	3,568	8,655
Amortization of deferred charge assets and deferred gain liabilities, current period									0	0	0
Amortization of fair value adjustments, current period									0	0	0
Net incurred losses and LAE, current period									263,562	354,884	422,191
Total
Net losses paid									326,868	450,835	427,371
Net change in case and LAE reserves									(95,044)	(4,686)	63,861
Net change in IBNR reserves									17,654	22,021	46,501
Increase (reduction) in estimates of net ultimate losses									249,478	468,170	537,733
Increase (reduction) in provisions for unallocated LAE									17,244	902	5,613
Amortization of deferred charge assets and deferred gain liabilities									606	0	0
Amortization of fair value adjustments									(590)	168	(266)
Changes in fair value - fair value option									0	0	0
Total net incurred losses and LAE									266,738	469,240	543,080
Other
Total
Net losses paid									9,800	11,822	4,092
Net change in case and LAE reserves									692	3,460	4,808
Net change in IBNR reserves									6,475	756	7,999
Increase (reduction) in estimates of net ultimate losses									16,967	16,038	16,899
Increase (reduction) in provisions for unallocated LAE									0	0	0
Amortization of deferred charge assets and deferred gain liabilities									0	0	0
Amortization of fair value adjustments									0	0	0
Changes in fair value - fair value option									0	0	0
Total net incurred losses and LAE									$ 16,967	$ 16,038	$ 16,899

Losses and Loss Adjustment Expenses - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) commutation	Dec. 31, 2019 USD ($) commutation policy_buy_back	Dec. 31, 2018 USD ($) commutation
Effects of Reinsurance [Line Items]
Net liabilities relating to direct asbestos and environmental exposures	$ 1,900,000	$ 2,100,000
Asbestos and environmental liabilities	2,100,000	2,300,000
Increase (decrease) in asbestos and environmental reserves, gross	(178,200)	(419,900)
Increase (decrease) in asbestos and environmental reserves, net	(227,200)	(374,700)
Net losses paid, prior period	1,413,500	1,609,009	$ 1,158,614
Net incurred losses and LAE, current period	405,178	580,074	533,081
Changes in fair value - fair value option	119,046	117,181	6,664
Atrium
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	(5,722)	(8,086)	(8,699)
Net losses paid, prior period	40,196	43,572	28,969
Net change in case and LAE reserves, prior period	(14,145)	(13,278)	(10,161)
Downward incurred loss development	(31,773)	(38,380)	(27,507)
Increase (decrease) in net incurred losses and LAE, current period	10,000
Net incurred losses and LAE, current period	93,471	85,027	83,627
Changes in fair value - fair value option	0	0	0
Atrium \| COVID-19
Effects of Reinsurance [Line Items]
Net incurred losses and LAE, current period	18,400
Non-life Run-off
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	(127,116)	(219,085)	(286,439)
Net losses paid, prior period	1,064,911	1,182,804	838,812
Net change in case and LAE reserves, prior period	(449,610)	(553,996)	(552,124)
Downward incurred loss development	(742,417)	(847,893)	(573,127)
Net incurred losses and LAE, current period	30,165	123,559	12,451
Changes in fair value - fair value option	119,046	117,181	6,664
Non-life Run-off \| Workers' compensation/personal accident
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	(183,335)	(136,418)	(154,560)
Net losses paid, prior period	142,790	208,961	139,226
Net change in case and LAE reserves, prior period	(176,927)	(156,435)	(178,138)
Increase (decrease) in reported losses	(34,100)
Downward incurred loss development	(149,198)	(188,944)	$ (115,648)
Reduction of open inventory claims, percentage			(78.00%)
Non-life Run-off \| Workers' compensation, two portfolios
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period		39,300
Net change in case and LAE reserves, prior period		53,600
Downward incurred loss development		14,300
Non-life Run-off \| Six Communications
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	$ (10,800)	$ (6,100)
Number of commutations \| commutation	10	6
Non-life Run-off \| Seven Communications
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period			$ 11,200
Number of commutations \| commutation			7
Non-life Run-off \| Marine, aviation and transit
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	$ (31,089)	$ (20,408)	$ 2,443
Net losses paid, prior period	33,927	82,058	67,831
Net change in case and LAE reserves, prior period	(14,458)	(77,958)	(44,200)
Downward incurred loss development	(50,558)	(24,508)	(21,188)
Non-life Run-off \| General Casualty
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	(25,663)	(6,742)	(34,444)
Net losses paid, prior period	170,502	175,044	141,624
Net change in case and LAE reserves, prior period	(68,744)	(89,968)	(115,240)
Downward incurred loss development	(127,421)	(91,818)	(60,828)
Non-life Run-off \| Motor
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	147,765	(37,451)	(39,995)
Net losses paid, prior period	349,366	276,563	104,182
Net change in case and LAE reserves, prior period	(106,561)	(134,127)	(109,962)
Downward incurred loss development	(95,040)	(179,887)	(34,215)
Non-life Run-off \| Professional indemnity/ Directors & Officers
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	(11,605)	(38,557)	19,681
Net losses paid, prior period	63,878	103,413	161,797
Net change in case and LAE reserves, prior period	3,698	(36,986)	(11,159)
Downward incurred loss development	(79,181)	(104,984)	(130,957)
Ceded reinsurance asset increase		13,500
Non-life Run-off \| Asbestos
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	(18,501)	6,811	(64,949)
Net losses paid, prior period	132,853	118,557	108,248
Net change in case and LAE reserves, prior period	(1,300)	35,003	(21,535)
Downward incurred loss development	(150,054)	(146,749)	$ (151,662)
Volume of claims reported, percentage, less than			3.00%
Average cost per claims, percentage			5.00%
Non-life Run-off \| Asbestos Exposure, Six Commutations
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period		$ (9,800)
Number of commutations \| commutation		6
Non-life Run-off \| Asbestos Exposure, Eight Communications and Two Policy Buy-Backs
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period			$ (9,500)
Number of commutations \| commutation			8
Number of policy buy-backs \| policy_buy_back		2
Non-life Run-off \| Product And Service Other Than Workers' Compensation
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	$ (12,300)
Number of commutations \| commutation	15
StarStone
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	$ 3,626	$ 116,854	$ 124,197
Net losses paid, prior period	300,037	375,377	289,981
Net change in case and LAE reserves, prior period	(130,502)	(95,183)	(77,821)
Downward incurred loss development	(165,909)	(163,340)	(87,963)
Increase (decrease) in net incurred losses and LAE, current period	(202,500)	(73,800)
Net incurred losses and LAE, current period	263,562	354,884	422,191
Changes in fair value - fair value option	0	$ 0	0
StarStone \| COVID-19
Effects of Reinsurance [Line Items]
Net incurred losses and LAE, current period	$ 52,800
Short-duration Insurance Contracts, Accident Years 1995-2005 \| Non-life Run-off \| Workers' compensation/personal accident
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period			22,700
Net change in case and LAE reserves, prior period			37,000
Downward incurred loss development			14,300
Short-duration Insurance Contracts, Accident Years 2010-2014 \| Non-life Run-off \| Workers' compensation/personal accident
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period			$ (30,200)

Losses and Loss Adjustment Expenses - Net Incurred Losses by Line of Business (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	$ 1,413,500	$ 1,609,009	$ 1,158,614
Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	1,064,911	1,182,804	838,812
Net change in case and LAE reserves, prior period	(449,610)	(553,996)	(552,124)
Net change in IBNR reserves, prior period	(742,417)	(847,893)	(573,127)
Increase (reduction) in estimates of net ultimate losses, prior period	(127,116)	(219,085)	(286,439)
Asbestos \| Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	132,853	118,557	108,248
Net change in case and LAE reserves, prior period	(1,300)	35,003	(21,535)
Net change in IBNR reserves, prior period	(150,054)	(146,749)	(151,662)
Increase (reduction) in estimates of net ultimate losses, prior period	(18,501)	6,811	(64,949)
Environmental \| Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	23,866	16,899	21,273
Net change in case and LAE reserves, prior period	(266)	13,796	479
Net change in IBNR reserves, prior period	(36,362)	(15,707)	(7,599)
Increase (reduction) in estimates of net ultimate losses, prior period	(12,762)	14,988	14,153
General Casualty \| Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	170,502	175,044	141,624
Net change in case and LAE reserves, prior period	(68,744)	(89,968)	(115,240)
Net change in IBNR reserves, prior period	(127,421)	(91,818)	(60,828)
Increase (reduction) in estimates of net ultimate losses, prior period	(25,663)	(6,742)	(34,444)
Workers' compensation/personal accident \| Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	142,790	208,961	139,226
Net change in case and LAE reserves, prior period	(176,927)	(156,435)	(178,138)
Net change in IBNR reserves, prior period	(149,198)	(188,944)	(115,648)
Increase (reduction) in estimates of net ultimate losses, prior period	(183,335)	(136,418)	(154,560)
Marine, aviation and transit \| Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	33,927	82,058	67,831
Net change in case and LAE reserves, prior period	(14,458)	(77,958)	(44,200)
Net change in IBNR reserves, prior period	(50,558)	(24,508)	(21,188)
Increase (reduction) in estimates of net ultimate losses, prior period	(31,089)	(20,408)	2,443
Construction defect \| Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	27,476	32,078	22,182
Net change in case and LAE reserves, prior period	(6,092)	(8,313)	(7,257)
Net change in IBNR reserves, prior period	(13,382)	(25,025)	(33,146)
Increase (reduction) in estimates of net ultimate losses, prior period	8,002	(1,260)	(18,221)
Professional indemnity/ Directors & Officers \| Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	63,878	103,413	161,797
Net change in case and LAE reserves, prior period	3,698	(36,986)	(11,159)
Net change in IBNR reserves, prior period	(79,181)	(104,984)	(130,957)
Increase (reduction) in estimates of net ultimate losses, prior period	(11,605)	(38,557)	19,681
Motor \| Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	349,366	276,563	104,182
Net change in case and LAE reserves, prior period	(106,561)	(134,127)	(109,962)
Net change in IBNR reserves, prior period	(95,040)	(179,887)	(34,215)
Increase (reduction) in estimates of net ultimate losses, prior period	147,765	(37,451)	(39,995)
Property \| Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	71,422	94,093	22,178
Net change in case and LAE reserves, prior period	(24,356)	(73,259)	(24,271)
Net change in IBNR reserves, prior period	(64,331)	(7,358)	(11,497)
Increase (reduction) in estimates of net ultimate losses, prior period	(17,265)	13,476	(13,590)
All Other \| Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	48,831	75,138	50,271
Net change in case and LAE reserves, prior period	(54,604)	(25,749)	(40,841)
Net change in IBNR reserves, prior period	23,110	(62,913)	(6,387)
Increase (reduction) in estimates of net ultimate losses, prior period	$ 17,337	$ (13,524)	$ 3,043

Losses and Loss Adjustment Expenses - Breakdown of Gross and Net Losses and LAE Reserves by Major Category (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Gross
OLR	$ 5,127,849	$ 5,249,565
IBNR	5,277,503	4,651,649
Fair value adjustments - acquired companies	(143,183)	(167,511)
Fair value adjustments - fair value option	(54,589)	(217,933)
Total	10,593,282	9,868,404	$ 9,048,796	$ 7,100,488
Net
ULAE	385,702	352,634
Total	8,544,940	7,681,193	7,253,939
Non-life Run-off
Gross
OLR	4,440,425	4,407,082
IBNR	4,641,500	3,945,407
Total	9,081,925	8,352,489
Fair value adjustments - acquired companies	(142,854)	(170,689)
Fair value adjustments - fair value option	(54,589)	(217,933)
Net deferred charge assets and gains on retroactive reinsurance	0	0
ULAE	350,600	331,494
Total	9,235,082	8,295,361	7,540,662	5,949,472
Net
OLR	3,502,195	3,434,789
IBNR	4,133,418	3,272,348
Total Net Reserves	7,635,613	6,707,137
Fair value adjustments	(128,841)	(157,036)
Fair value adjustments - fair value option	(33,163)	(129,848)
Net deferred charge assets and gains on retroactive reinsurance	(218,722)	(259,587)
ULAE	333,913	331,494
Total	7,588,800	6,492,160	6,087,954
Non-life Run-off \| Asbestos
Gross
OLR	544,438	542,681
IBNR	1,234,101	1,373,678
Total	1,778,539	1,916,359
Net
OLR	464,102	490,117
IBNR	1,122,021	1,271,982
Total Net Reserves	1,586,123	1,762,099
Non-life Run-off \| Environmental
Gross
OLR	184,783	187,165
IBNR	118,111	156,121
Total	302,894	343,286
Net
OLR	164,709	173,878
IBNR	100,339	142,351
Total Net Reserves	265,048	316,229
Non-life Run-off \| General Casualty
Gross
OLR	610,437	501,863
IBNR	1,279,991	489,129
Total	1,890,428	990,992
Net
OLR	492,039	399,396
IBNR	1,247,662	421,426
Total Net Reserves	1,739,701	820,822
Non-life Run-off \| Workers' compensation/personal accident
Gross
OLR	1,087,324	1,270,530
IBNR	918,238	977,808
Total	2,005,562	2,248,338
Net
OLR	912,068	963,578
IBNR	776,941	751,074
Total Net Reserves	1,689,009	1,714,652
Non-life Run-off \| Marine, aviation and transit
Gross
OLR	271,469	290,067
IBNR	73,081	121,577
Total	344,550	411,644
Net
OLR	229,464	244,611
IBNR	56,414	100,135
Total Net Reserves	285,878	344,746
Non-life Run-off \| Construction defect
Gross
OLR	23,380	29,772
IBNR	85,578	98,312
Total	108,958	128,084
Net
OLR	23,109	29,245
IBNR	83,039	94,888
Total Net Reserves	106,148	124,133
Non-life Run-off \| Professional indemnity/ Directors & Officers
Gross
OLR	764,768	693,760
IBNR	336,705	265,490
Total	1,101,473	959,250
Net
OLR	526,333	485,478
IBNR	307,349	170,926
Total Net Reserves	833,682	656,404
Non-life Run-off \| Motor
Gross
OLR	619,682	480,668
IBNR	355,044	233,806
Total	974,726	714,474
Net
OLR	451,097	317,829
IBNR	283,576	165,543
Total Net Reserves	734,673	483,372
Non-life Run-off \| Property
Gross
OLR	116,398	140,620
IBNR	35,832	63,604
Total	152,230	204,224
Net
OLR	97,826	122,010
IBNR	34,182	56,450
Total Net Reserves	132,008	178,460
Non-life Run-off \| All Other
Gross
OLR	217,746	269,956
IBNR	204,819	165,882
Total	422,565	435,838
Net
OLR	141,448	208,647
IBNR	121,895	97,573
Total Net Reserves	263,343	306,220
Atrium
Gross
OLR		89,141
IBNR		136,543
Total		225,684
Fair value adjustments - acquired companies		3,700
ULAE		2,288
Total	0	231,672	241,284	240,873
Net
OLR		80,130
IBNR		117,257
Total Net Reserves		197,387
Fair value adjustments		3,181
ULAE		2,288
Total	0	202,856	202,516
Atrium \| Marine, aviation and transit
Gross
OLR		24,668
IBNR		34,156
Total		58,824
Net
OLR		21,012
IBNR		24,829
Total Net Reserves		45,841
Atrium \| Binding Authorities
Gross
OLR		31,507
IBNR		54,039
Total		85,546
Net
OLR		29,590
IBNR		51,984
Total Net Reserves		81,574
Atrium \| Reinsurance
Gross
OLR		18,385
IBNR		29,533
Total		47,918
Net
OLR		16,209
IBNR		23,338
Total Net Reserves		39,547
Atrium \| Accident and Health
Gross
OLR		5,460
IBNR		7,880
Total		13,340
Net
OLR		4,735
IBNR		7,469
Total Net Reserves		12,204
Atrium \| Non-Marine Direct and Facultative
Gross
OLR		9,121
IBNR		10,935
Total		20,056
Net
OLR		8,584
IBNR		9,637
Total Net Reserves		18,221
StarStone
Gross
OLR	677,220	743,830
IBNR	615,963	556,134
Total	1,293,183	1,299,964
Fair value adjustments - acquired companies	(329)	(522)
ULAE	35,102	18,852
Total	1,327,956	1,318,294	1,247,989	$ 910,143
Net
OLR	413,582	479,699
IBNR	476,203	462,949
Total Net Reserves	889,785	942,648
Fair value adjustments	1,010	1,600
ULAE	35,101	18,852
Total	925,896	963,100	$ 944,608
StarStone \| General Casualty
Gross
OLR	115,295	121,945
IBNR	276,941	210,969
Total	392,236	332,914
Net
OLR	98,721	108,543
IBNR	232,433	204,800
Total Net Reserves	331,154	313,343
StarStone \| Workers' compensation/personal accident
Gross
OLR	12,044	15,089
IBNR	11,589	19,865
Total	23,633	34,954
Net
OLR	12,044	15,089
IBNR	11,589	19,865
Total Net Reserves	23,633	34,954
StarStone \| Property
Gross
OLR	322,735	341,677
IBNR	117,240	131,596
Total	439,975	473,273
Net
OLR	141,089	150,559
IBNR	81,459	87,653
Total Net Reserves	222,548	238,212
StarStone \| Marine
Gross
OLR	142,631	189,355
IBNR	174,015	161,379
Total	316,646	350,734
Net
OLR	119,628	158,252
IBNR	132,482	128,242
Total Net Reserves	252,110	286,494
StarStone \| Aerospace
Gross
OLR	84,515	75,764
IBNR	36,178	32,325
Total	120,693	108,089
Net
OLR	42,100	47,256
IBNR	18,240	22,389
Total Net Reserves	$ 60,340	$ 69,645

Losses and Loss Adjustment Expenses - Reconciliation Of Net Incurred Losses Prior To Provision For Bad Debt (Details) - Non-life Run-off - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	$ 7,587,170
Provision for Bad Debt	48,443
Total Net Reserves	7,635,613	$ 6,707,137
Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	1,563,706
Provision for Bad Debt	22,417
Total Net Reserves	1,586,123	1,762,099
Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	261,387
Provision for Bad Debt	3,661
Total Net Reserves	265,048	316,229
General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	1,732,445
Provision for Bad Debt	7,256
Total Net Reserves	1,739,701	820,822
Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	1,687,272
Provision for Bad Debt	1,737
Total Net Reserves	1,689,009	1,714,652
Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	283,868
Provision for Bad Debt	2,010
Total Net Reserves	285,878	344,746
Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	106,135
Provision for Bad Debt	13
Total Net Reserves	106,148	124,133
Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	833,085
Provision for Bad Debt	597
Total Net Reserves	833,682	656,404
Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	732,268
Provision for Bad Debt	2,405
Total Net Reserves	734,673	483,372
Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	130,309
Provision for Bad Debt	1,699
Total Net Reserves	132,008	178,460
All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	256,695
Provision for Bad Debt	6,648
Total Net Reserves	$ 263,343	$ 306,220

Losses and Loss Adjustment Expenses - Average Annual Duration of Claims (Details)	Dec. 31, 2020
StarStone \| Workers' compensation/personal accident
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	14.40%
Year 2	29.38%
Year 3	20.46%
Year 4	11.77%
Year 5	5.19%
Year 6	2.57%
Year 7	1.61%
Year 8	0.00%
Year 9	0.00%
Year 10	0.00%
StarStone \| General Casualty
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	7.72%
Year 2	20.87%
Year 3	17.53%
Year 4	15.99%
Year 5	9.96%
Year 6	4.35%
Year 7	7.85%
Year 8	9.00%
Year 9	0.06%
Year 10	0.08%
StarStone \| Marine
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	18.17%
Year 2	30.97%
Year 3	19.08%
Year 4	9.99%
Year 5	5.02%
Year 6	2.46%
Year 7	3.48%
Year 8	2.04%
Year 9	0.99%
Year 10	0.39%
StarStone \| Property
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	19.10%
Year 2	28.75%
Year 3	26.40%
Year 4	8.35%
Year 5	2.47%
Year 6	2.69%
Year 7	1.55%
Year 8	1.01%
Year 9	0.02%
Year 10	0.30%
StarStone \| Aerospace
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	32.80%
Year 2	29.84%
Year 3	15.40%
Year 4	4.61%
Year 5	4.31%
Year 6	2.22%
Year 7	1.93%
Year 8	1.12%
Year 9	0.48%
Year 10	0.01%
2011 \| Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	25.68%
Year 2	17.45%
Year 3	(3.59%)
Year 4	(28.95%)
Year 5	(2.12%)
Year 6	3.57%
Year 7	(3.49%)
Year 8	4.99%
Year 9	11.18%
Year 10	8.86%
2012 \| Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	1.30%
Year 2	26.42%
Year 3	16.71%
Year 4	12.48%
Year 5	10.00%
Year 6	4.47%
Year 7	5.48%
Year 8	4.17%
Year 9	2.12%
2013 \| Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	25.96%
Year 2	21.67%
Year 3	15.93%
Year 4	11.01%
Year 5	6.15%
Year 6	3.89%
Year 7	2.24%
Year 8	0.32%
2014 \| Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	33.84%
Year 2	24.15%
Year 3	11.11%
Year 4	8.07%
Year 5	3.74%
Year 6	1.65%
Year 7	1.10%
2015 \| Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	17.33%
Year 2	17.09%
Year 3	12.84%
Year 4	9.80%
Year 5	7.69%
Year 6	4.65%
2015 \| Non-life Run-off \| Workers' compensation/personal accident
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	13.72%
Year 2	17.09%
Year 3	12.73%
Year 4	9.73%
Year 5	6.71%
Year 6	4.27%
2016 \| Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	7.67%
Year 2	9.18%
Year 3	7.99%
Year 4	8.41%
Year 5	6.86%
2016 \| Non-life Run-off \| Workers' compensation/personal accident
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	10.33%
Year 2	8.96%
Year 3	7.09%
Year 4	9.89%
Year 5	8.22%
2017 \| Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	8.04%
Year 2	7.64%
Year 3	6.71%
Year 4	6.11%
2018 \| Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	12.86%
Year 2	25.40%
Year 3	12.00%
2018 \| Non-life Run-off \| Workers' compensation/personal accident
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	2.03%
Year 2	19.49%
Year 3	10.03%
2018 \| Non-life Run-off \| General Casualty
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	11.31%
Year 2	21.69%
Year 3	17.77%
2018 \| Non-life Run-off \| Professional indemnity/ Directors & Officers
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	19.55%
Year 2	14.40%
Year 3	5.34%
2018 \| Non-life Run-off \| Motor
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	11.08%
Year 2	38.47%
Year 3	17.61%
2019 \| Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	11.11%
Year 2	12.68%
2019 \| Non-life Run-off \| Workers' compensation/personal accident
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	3.67%
Year 2	2.02%
2019 \| Non-life Run-off \| General Casualty
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	8.82%
Year 2	7.43%
2020 \| Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	11.43%
2020 \| Non-life Run-off \| General Casualty
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	3.32%
2020 \| Non-life Run-off \| Professional indemnity/ Directors & Officers
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	1.30%
2020 \| Non-life Run-off \| Motor
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	32.78%

Losses and Loss Adjustment Expenses - Reconciliation of Incurred and Paid Loss Development (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Atrium
Liability for Claims and Claims Adjustment Expense [Line Items]
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments		$ 225,684
StarStone
Liability for Claims and Claims Adjustment Expense [Line Items]
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$ 1,293,183	1,299,964
StarStone \| General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	331,154
Reinsurance recoverable on unpaid losses	61,082
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	392,236	332,914
StarStone \| Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	252,110
Reinsurance recoverable on unpaid losses	64,536
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	316,646	350,734
StarStone \| Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	222,548
Reinsurance recoverable on unpaid losses	217,427
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	439,975	473,273
StarStone \| Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	60,340
Reinsurance recoverable on unpaid losses	60,353
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	120,693	108,089
StarStone \| Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	23,633
Reinsurance recoverable on unpaid losses	0
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$ 23,633	$ 34,954

Defendant Asbestos and Environmental Liabilities - Liability for Asbestos and Liability Claims (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Estimated future expenses	$ 42,510	$ 51,637
Fair value adjustments	(262,029)	(314,824)
Defendant asbestos and environmental liabilities	706,329	847,685	$ 203,320	$ 219,164
Insurance recoveries related to defendant asbestos liabilities (net of allowance: 2020 - $4,824)	310,602	549,593
Fair value adjustments	(60,950)	(100,738)
Insurance balances recoverable	249,652	448,855	135,808	$ 122,326
Net liabilities relating to defendant asbestos and environmental exposures	456,677	398,830	67,512
Insurance balance recoverable, allowance for credit loss	4,824	3,818	$ 0
Defendant asbestos liabilities
Loss Contingencies [Line Items]
Defendant asbestos and environmental liabilities	913,276	1,100,593
Defendant environmental liabilities
Loss Contingencies [Line Items]
Defendant asbestos and environmental liabilities	$ 12,572	$ 10,279

Defendant Asbestos and Environmental Liabilities - Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Balance as of January 1	$ 847,685	$ 203,320	$ 219,164
Less: Insurance balances recoverable	448,855	135,808	122,326
Plus: Cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible insurance balances	4,824	3,818	0
Net balance as of January 1	398,830	67,512
Total net recoveries (paid claims)	153,964	(10,434)	(6,351)
Amounts recorded in other income (expense):
Change in estimate of net ultimate liabilities	(103,166)	(4,263)	(23,221)
Reduction in estimated future expenses	(9,126)	(3,274)	0
Amortization of fair value adjustments	13,008	13,500	246
Total other expense (income)	(99,284)	5,963	(22,975)
Acquired on purchase of subsidiaries	0	335,789	0
Net balance as of December 31	456,677	398,830	67,512
Plus: insurance balances recoverable	249,652	448,855	135,808
Balance as of December 31	706,329	847,685	203,320
Cumulative effect of change in accounting principle
Liability for Claims and Claims Adjustment Expense [Line Items]
Plus: Cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible insurance balances		3,167	0	$ 0
Cumulative effect of change in accounting principle, adjusted balance
Liability for Claims and Claims Adjustment Expense [Line Items]
Net balance as of January 1	$ 401,997	67,512	96,838
Amounts recorded in other income (expense):
Net balance as of December 31		$ 401,997	$ 67,512

Defendant Asbestos and Environmental Liabilities - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) site	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
Other expense (income)	$ (99,284)	$ 5,963	$ (22,975)
Collection of disputed insurance recoveries	166,700
Proceeds from disputed insurance recoveries	179,600
Recovery of previously written-off insurance payments	19,300
Asbestos and environmental liabilities	$ 2,100,000	2,300,000
Number of hazardous waste disposal sites \| site	22
Defendant asbestos liabilities
Liability for Claims and Claims Adjustment Expense [Line Items]
Asbestos and environmental liabilities	$ 913,300	1,100,000
Defendant environmental liabilities
Liability for Claims and Claims Adjustment Expense [Line Items]
Asbestos and environmental liabilities	$ 12,600	$ 10,300

Defendant Asbestos and Environmental Liabilities - Allowance for Credit Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Liability For Asbestos And Environmental Claims, Allowance for Credit Loss [Roll Forward]
Allowance for estimated uncollectible insurance balances, beginning of year	$ 3,818	$ 0
Current period change in the allowance	(2,161)	3,818
Allowance for estimated uncollectible insurance balances, end of year	4,824	3,818
Cumulative effect of change in accounting principle
Liability For Asbestos And Environmental Claims, Allowance for Credit Loss [Roll Forward]
Allowance for estimated uncollectible insurance balances, beginning of year	$ 3,167	0
Allowance for estimated uncollectible insurance balances, end of year		$ 3,167

Fair Value Measurements - Reconciliation for Investments Measured At Fair Value on Recurring Basis Level 3 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	$ 353,668	$ 321,973
Purchases	67,217	87,805
Sales	(1,289)	(10,515)
Total realized and unrealized losses	(51,551)	984
Transfer into Level 3 from Level 2		26,176
Transfer out of Level 3 into Level 2	(83,740)	(72,755)
Ending fair value	284,305	353,668
Corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	0	37,386
Purchases		184
Sales		(3,520)
Total realized and unrealized losses		90
Transfer into Level 3 from Level 2		3,535
Transfer out of Level 3 into Level 2		(37,675)
Ending fair value		0
Residential mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	0	0
Purchases		0
Sales		0
Total realized and unrealized losses		(1)
Transfer into Level 3 from Level 2		102
Transfer out of Level 3 into Level 2		(101)
Ending fair value		0
Commercial mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	0	7,389
Purchases		0
Sales		(784)
Total realized and unrealized losses		64
Transfer into Level 3 from Level 2		1,515
Transfer out of Level 3 into Level 2		(8,184)
Ending fair value		0
Asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	0	9,121
Purchases		0
Sales		(3,605)
Total realized and unrealized losses		255
Transfer into Level 3 from Level 2		21,024
Transfer out of Level 3 into Level 2		(26,795)
Ending fair value		0
Privately-held Equities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	265,799	228,710
Purchases	20,125	30,713
Sales	0	(2,016)
Total realized and unrealized losses	(11,183)	8,392
Transfer into Level 3 from Level 2		0
Transfer out of Level 3 into Level 2	0	0
Ending fair value	274,741	265,799
Other Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	87,869	39,367
Purchases	47,092	56,908
Sales	(1,289)	(590)
Total realized and unrealized losses	(40,368)	(7,816)
Transfer into Level 3 from Level 2		0
Transfer out of Level 3 into Level 2	(83,740)	0
Ending fair value	$ 9,564	$ 87,869

Fair Value Measurements - Valuation Techniques and Inputs (Details) - Private equity funds - Significant Unobservable Inputs (Level 3) $ in Millions	Dec. 31, 2020 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 284.3
Guideline company methodology
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	230.3
Cost as approximation of fair value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 54.0
Arithmetic Average \| Guideline company methodology \| Distribution waterfall
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investments, measurement input	12.98

Fair Value Measurements - Insurance Contracts - Fair Value Option (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reinsurance balances recoverable on paid and unpaid losses
Beginning fair value	$ 353,668	$ 321,973
Assumed business	67,217	87,805
Incurred losses and LAE:
Change in fair value	(51,551)	984
Ending fair value	284,305	353,668	$ 321,973
Net
Beginning fair value	1,925,604	2,134,464
Assumed business	182,498	9,218
Incurred losses and LAE:
Reduction in estimates of ultimate losses	(133,074)	(29,732)
Reduction in unallocated LAE	(17,484)	(19,915)
Change in fair value	119,046	117,181	6,664
Total incurred losses and LAE	(31,512)	67,534
Paid losses	(198,908)	(324,625)
Effect of exchange rate movements	54,408	39,013
Ending fair value	1,932,090	1,925,604	2,134,464
Components of Changes in Fair Value
Change in fair value	119,046	117,181	6,664
Reinsurance balances recoverable on paid and unpaid losses
Reinsurance balances recoverable on paid and unpaid losses
Beginning fair value	695,518	739,591
Assumed business	(180,972)	0
Incurred losses and LAE:
Reduction in estimates of ultimate losses	59,478	(2,958)
Reduction in unallocated LAE	0	0
Change in fair value	38,919	43,449
Total incurred losses and LAE	98,397	40,491
Paid losses	(101,326)	(92,145)
Effect of exchange rate movements	9,213	7,581
Ending fair value	520,830	695,518	739,591
Liability for losses and LAE
Liability for losses and LAE
Beginning fair value	2,621,122	2,874,055
Assumed business	1,526	9,218
Incurred losses and LAE:
Reduction in estimates of ultimate losses	(73,596)	(32,690)
Reduction in unallocated LAE	(17,484)	(19,915)
Change in fair value	157,965	160,630
Total incurred losses and LAE	66,885	108,025
Paid losses	(300,234)	(416,770)
Effect of exchange rate movements	63,621	46,594
Ending fair value	2,452,920	2,621,122	2,874,055
Duration
Incurred losses and LAE:
Change in fair value	20,861	22,719	74,011
Components of Changes in Fair Value
Change in fair value	20,861	22,719	74,011
Corporate bond yield
Incurred losses and LAE:
Change in fair value	96,478	94,462	(71,031)
Components of Changes in Fair Value
Change in fair value	96,478	94,462	(71,031)
Weighted cost of capital
Incurred losses and LAE:
Change in fair value	(5,048)	0
Components of Changes in Fair Value
Change in fair value	(5,048)	0
Risk cost of capital
Incurred losses and LAE:
Change in fair value	6,755	0	3,684
Components of Changes in Fair Value
Change in fair value	$ 6,755	$ 0	$ 3,684

Fair Value Measurements - Quantitative Information (Details) - Internal Model - Recurring	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Liability for losses and LAE
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Weighted average cost of capital	8.25%	8.50%
Fair value inputs, duration	8 years 2 months 1 day	7 years 9 months 25 days
Reinsurance balances recoverable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk cost of capital	5.10%	5.10%
Fair value inputs, duration	8 years 2 months 23 days	8 years 8 months 4 days
Credit spread for non-performing risk \| Liability for losses and LAE
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit spread for non-performing risk	0.20%	0.20%

Fair Value Measurements - Fair Values for Financial Instruments Carried At Cost (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Aug. 26, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of debt	$ 1,373,259		$ 1,191,207
Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of debt	$ 843,447		842,216
Senior Notes \| 4.50% Senior Notes due 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate	4.50%
Carrying value of debt	$ 349,253		348,616
Fair value of debt	$ 362,400
Senior Notes \| 4.95% Senior Notes due 2029
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate	4.95%
Carrying value of debt	$ 494,194		493,600
Fair value of debt	$ 573,300
Junior Subordinated Notes \| 5.75% Junior Subordinated Notes due 2040
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate	5.75%	5.75%
Carrying value of debt	$ 344,812		$ 0
Fair value of debt	$ 365,700

Premiums Written and Earned - Schedule of Net Premiums Written and Earned (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effects of Reinsurance [Line Items]
Gross, premiums written									$ 551,983	$ 658,653	$ 817,532
Ceded, premiums written									(119,159)	(113,600)	(163,185)
Net, premiums written									432,824	545,053	654,347
Gross, premiums earned									729,918	949,530	862,113
Ceded, premiums earned									(157,826)	(145,483)	(166,334)
Net, premiums earned	$ 108,146	$ 161,724	$ 142,871	$ 159,351	$ 185,336	$ 175,802	$ 190,962	$ 251,947	572,092	804,047	695,779
Operating Segments \| Non-life Run-off
Effects of Reinsurance [Line Items]
Gross, premiums written									5,191	(25,069)	(8,910)
Ceded, premiums written									(2,204)	(269)	(307)
Net, premiums written									2,987	(25,338)	(9,217)
Gross, premiums earned									71,522	197,009	25,230
Ceded, premiums earned									(12,827)	(28,513)	(15,803)
Net, premiums earned									58,695	168,496	9,427
Operating Segments \| Atrium
Effects of Reinsurance [Line Items]
Gross, premiums written									206,656	192,373	171,494
Ceded, premiums written									(23,462)	(20,017)	(18,006)
Net, premiums written									183,194	172,356	153,488
Gross, premiums earned									197,492	182,678	164,428
Ceded, premiums earned									(22,099)	(18,619)	(18,113)
Net, premiums earned									175,393	164,059	146,315
Operating Segments \| StarStone
Effects of Reinsurance [Line Items]
Gross, premiums written									326,695	472,815	622,570
Ceded, premiums written									(93,493)	(93,292)	(144,561)
Net, premiums written									233,202	379,523	478,009
Gross, premiums earned									441,015	549,299	647,218
Ceded, premiums earned									(122,900)	(98,187)	(132,055)
Net, premiums earned									318,115	451,112	515,163
Other
Effects of Reinsurance [Line Items]
Gross, premiums written									13,441	18,534	32,378
Ceded, premiums written									0	(22)	(311)
Net, premiums written									13,441	18,512	32,067
Gross, premiums earned									19,889	20,544	25,237
Ceded, premiums earned									0	(164)	(363)
Net, premiums earned									$ 19,889	$ 20,380	$ 24,874

Premiums Written and Earned - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Insurance [Abstract]
Decrease in premiums written, gross	$ 106.7	$ 158.9

Goodwill and Intangible Assets- Schedule of Goodwill, Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill
Goodwill, Beginning balance	$ 109,807	$ 109,807
Impairment losses (StarStone International)	(8,000)
Reclassification to assets held-for-sale (Atrium)	(38,848)
Goodwill, Ending balance	62,959	109,807	$ 109,807
Intangible assets with a definite life
Intangible assets with a definite life, Beginning balance	14,630	16,887
Amortization	(1,524)	(2,257)	(3,600)
Impairment losses (StarStone International)	0
Reclassification to assets held-for-sale (Atrium)	(13,106)
Intangible assets with a definite life, Ending balance	0	14,630	16,887
Intangible assets with an indefinite life
Intangible assets with an indefinite life, Beginning balance	67,131	67,131
Impairment losses (StarStone International)	(4,000)
Reclassification to assets held-for-sale (Atrium)	(63,131)
Intangible assets with an indefinite life, Ending balance	0	67,131	67,131
Goodwill and Intangible Assets [Roll Forward]
Goodwill and intangible assets, Beginning Balance	191,568	193,825
Impairment losses (StarStone International)	12,000
Reclassification to assets held-for-sale (Atrium)	115,085
Goodwill and intangible assets, Ending balance	62,959	191,568	$ 193,825
StarStone
Goodwill
Goodwill, Beginning balance	8,000
Impairment losses (StarStone International)	(8,000)
Goodwill, Ending balance	0	8,000
Goodwill and Intangible Assets [Roll Forward]
Goodwill and intangible assets, Beginning Balance	12,000
Goodwill and intangible assets, Ending balance	0	12,000
Lloyd’s syndicate capacity \| StarStone
Intangible assets with an indefinite life
Intangible assets with an indefinite life, Beginning balance	4,000
Impairment losses (StarStone International)	(4,000)
Intangible assets with an indefinite life, Ending balance	$ 0	$ 4,000

Goodwill and Intangible Assets - Summary of Gross Carrying Value, Accumulated Amortization and Net Carrying Value of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill
Net carrying value	$ 62,959	$ 109,807	$ 109,807
Intangible assets with a definite life:
Accumulated amortization	0	(12,370)
Net carrying value	0	14,630	16,887
Intangible assets with an indefinite life:
Net carrying value	0	67,131	67,131
Gross carrying value	62,959	203,938
Net carrying value	62,959	191,568	$ 193,825
Non-life Run-off
Goodwill
Goodwill	62,959	62,959
Net carrying value	62,959	62,959
Atrium
Goodwill
Goodwill	0	38,848
Net carrying value	0	38,848
Intangible assets with a definite life:
Accumulated amortization	0	(12,370)
Intangible assets with an indefinite life:
Gross carrying value	0	128,979
Net carrying value	0	116,609
Atrium \| Distribution channel
Intangible assets with a definite life:
Gross carrying value	0	20,000
Accumulated amortization	0	(8,111)
Net carrying value	0	11,889
Atrium \| Brand
Intangible assets with a definite life:
Gross carrying value	0	7,000
Accumulated amortization	0	(4,259)
Net carrying value	0	2,741
StarStone
Goodwill
Goodwill	0	8,000
Net carrying value	0	8,000
Intangible assets with an indefinite life:
Gross carrying value	0	12,000
Net carrying value	0	12,000
Lloyd’s syndicate capacity \| Atrium
Intangible assets with an indefinite life:
Gross carrying value	0	33,031
Net carrying value	0	33,031
Lloyd’s syndicate capacity \| StarStone
Intangible assets with an indefinite life:
Gross carrying value	0	4,000
Net carrying value	0	4,000
Management contract \| Atrium
Intangible assets with an indefinite life:
Gross carrying value	0	30,100
Net carrying value	$ 0	$ 30,100

Goodwill and Intangible Assets - Intangible Assets Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization	$ 1,524	$ 2,257	$ 3,600

Debt Obligations and Credit Facilities - Amounts of Outstanding Debt and Accrued Interest (Details) - USD ($) $ in Thousands			3 Months Ended								12 Months Ended
	Dec. 27, 2018	Aug. 16, 2018	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Carrying value of debt			$ 1,373,259				$ 1,191,207				$ 1,373,259	$ 1,191,207
Interest expense on debt obligations											57,974	51,245	$ 25,205
Amortization of debt issuance costs											1,331	953	537
Funds withheld balances and other											3	343	(46)
Total interest expense			16,872	$ 15,003	$ 14,018	$ 13,415	13,519	$ 14,950	$ 13,036	$ 11,036	59,308	52,541	$ 25,696
Senior Notes
Line of Credit Facility [Line Items]
Carrying value of debt			843,447				842,216				$ 843,447	842,216
Senior Notes \| 4.50% Senior Notes due 2022
Line of Credit Facility [Line Items]
Term											5 years
Carrying value of debt			349,253				348,616				$ 349,253	348,616
Senior Notes \| 4.95% Senior Notes due 2029
Line of Credit Facility [Line Items]
Term											10 years
Carrying value of debt			494,194				493,600				$ 494,194	493,600
Junior Subordinated Notes \| 5.75% Junior Subordinated Notes due 2040
Line of Credit Facility [Line Items]
Term											20 years
Carrying value of debt			344,812				0				$ 344,812	0
Loan facilities \| EGL Revolving Credit Facility
Line of Credit Facility [Line Items]
Term		5 years									5 years
Carrying value of debt							0					0
Loan facilities \| 2018 EGL Term Loan Facility
Line of Credit Facility [Line Items]
Term	3 years										3 years
Carrying value of debt			$ 0				$ 348,991				$ 0	$ 348,991

Debt Obligations and Credit Facilities - Senior Notes (Details) $ in Millions			12 Months Ended
	May 28, 2019 USD ($)	Mar. 10, 2017 USD ($)	Dec. 31, 2020 USD ($) debt_instrument
Debt Instrument [Line Items]
Number of debt instruments \| debt_instrument			2
Senior Notes \| 4.50% Senior Notes due 2022
Debt Instrument [Line Items]
Interest rate			4.50%
Redemption price, percentage of principal amount			100.00%
Debt issuance costs		$ 2.9
Unamortized costs of debt			$ (0.7)
Senior Notes \| 4.95% Senior Notes due 2029
Debt Instrument [Line Items]
Interest rate			4.95%
Debt issuance costs	$ 6.8
Unamortized costs of debt			$ (5.8)

Debt Obligations and Credit Facilities - Junior Subordinated Notes (Details) - 5.75% Junior Subordinated Notes due 2040 - Junior Subordinated Notes - USD ($)	12 Months Ended	180 Months Ended
	Dec. 31, 2020	Sep. 01, 2040	Aug. 26, 2020
Debt Instrument [Line Items]
Interest rate	5.75%		5.75%
Aggregate principal amount			$ 350,000,000.0
Redemption price, percentage of principal amount	100.00%
Unamortized costs	$ 5,200,000		$ 5,200,000
Scenario, Forecast \| Treasury rate
Debt Instrument [Line Items]
Basis spread on interest rate		5.468%

Debt Obligations and Credit Facilities - EGL Revolving Credit Facility (Details) - Loan facilities - EGL Revolving Credit Facility		2 Months Ended	12 Months Ended
	Aug. 16, 2018 USD ($)	Mar. 01, 2021 USD ($)	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Facility term	5 years		5 years
Maximum borrowing capacity	$ 600,000,000.0		$ 600,000,000.0
Increase in borrowing capacity, limit	$ 400,000,000.0
Available unutilized capacity			$ 415,000,000.0
Covenant compliance, consolidated indebtedness to total capitalization (not greater than)	0.35
Covenant compliance, net income (loss) threshold	$ 2,300,000,000
Covenant compliance, net income threshold percent	50.00%
Covenant compliance, percentage of proceeds of common stock issuance	50.00%
Subsequent Event
Debt Instrument [Line Items]
Available unutilized capacity		$ 425,000,000.0
Additional borrowings		(20,000,000.0)
Repayment of revolving credit facility		$ 30,000,000.0

Debt Obligations and Credit Facilities - EGL Term Loan Facilities (Details) - USD ($)		12 Months Ended
	Dec. 27, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Repayment of loans		$ 679,000,000	$ 742,574,000	$ 914,319,000
Loan facilities \| 2018 EGL Term Loan Facility
Debt Instrument [Line Items]
Facility term	3 years	3 years
Maximum borrowing capacity	$ 500,000,000.0
Repayment of loans		$ 350,000,000.0	$ 150,000,000.0

Debt Obligations and Credit Facilities - Maturities (Details)	Dec. 31, 2020 USD ($)
Receivables [Abstract]
2021	$ 0
2022	350,000,000.0
2023	185,000,000
2024	0
Thereafter	$ 850,000,000.0

Debt Obligations and Credit Facilities - Letters of Credit (Details)	Nov. 05, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 08, 2020 USD ($)	Dec. 08, 2020 GBP (£)	Aug. 04, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 06, 2019 USD ($)	Dec. 22, 2017 USD ($)
Debt Instrument [Line Items]
Cash and investments		$ 260,900,000				$ 639,300,000
Letters of Credit \| Cavello Letter of Credit Facility \| Loan facilities
Debt Instrument [Line Items]
Maximum borrowing capacity								$ 100,000,000.0
Letters of credit		100,000,000.0
Letters of Credit \| Mercantile Letter of Credit Facility \| Loan facilities
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 43,700,000	£ 32,000,000.0
Letters of credit		43,700,000
Letters of Credit \| Loan facilities \| FAL Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 275,000,000.0
Increase in borrowing capacity, limit	$ 75,000,000.0
Term extension	2 years
Available unutilized capacity		210,000,000.0				252,000,000.0
Letters of Credit \| Loan facilities \| 2018 Facility Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity							$ 120,000,000.0
Increase in borrowing capacity, limit							$ 60,000,000.0
Letters of credit		115,700,000				115,300,000
Letters of Credit \| Loan facilities \| Maiden Facility Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 800,000,000.0
Increase in borrowing capacity, limit					40,000,000.0
Letters of credit		$ 424,100,000				$ 608,000,000.0
Letters of Credit \| Loan facilities \| 2020 Letter of Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity					65,000,000.0
Letters of credit					$ 61,000,000.0

Noncontrolling Interest - Redeemable Noncontrolling Interest (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balance at beginning of year	$ 438,791	$ 458,543
Capital contributions	0	13,127
Dividends paid	0	(11,556)
Net losses attributable to RNCI	(27,512)	(12,029)
Change in unrealized gains (losses) on AFS investments attributable to RNCI	1,517	(126)
Change in currency translation adjustments attributable to RNCI	(1,397)	10
Change in redemption value of RNCI	(46,224)	(9,178)
Cumulative effect of change in accounting principle attributable to RNCI	261	0
Balance at end of year	$ 365,436	$ 438,791
North Bay \| Trident
Redeemable Noncontrolling Interest [Line Items]
Ownership interest held by noncontrolling owners	39.30%
North Bay \| Dowling
Redeemable Noncontrolling Interest [Line Items]
Ownership interest held by noncontrolling owners	1.70%
Subsidiaries \| North Bay \| Trident
Redeemable Noncontrolling Interest [Line Items]
Ownership interest held by noncontrolling owners	39.30%	39.30%
Subsidiaries \| North Bay \| Dowling
Redeemable Noncontrolling Interest [Line Items]
Ownership interest held by noncontrolling owners	1.70%	1.70%

Noncontrolling Interest - Noncontrolling Interest (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Noncontrolling Interest [Abstract]
Noncontrolling interest	$ 13,609	$ 14,168

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which is directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent (that is, noncontrolling interest, previously referred to as minority interest).

Shareholders' Equity - Voting Ordinary Shares (Details)			10 Months Ended	12 Months Ended
Shareholders' Equity - Voting Ordinary Shares (Details)	Jan. 21, 2020 shares	May 14, 2018 shares	Dec. 31, 2020 USD ($) vote $ / shares shares	Dec. 31, 2020 USD ($) vote $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($)	Mar. 09, 2020 USD ($)
Class of Stock [Line Items]
Authorized share capital (shares)			111,000,000	111,000,000	111,000,000
Ordinary shares, par value (dollars per share) \| $ / shares			$ 1	$ 1	$ 1
Preference shares (shares)			45,000,000	45,000,000	45,000,000
Preferred shares, par value (dollars per share) \| $ / shares			$ 1.00	$ 1.00	$ 1.00
Authorized repurchase amount \| $							$ 150,000,000.0
Treasury shares repurchased (shares)			178,280
Treasury shares repurchased, average price (dollars per share) \| $ / shares			$ 145.87
Price of repurchased stock \| $			$ 26,000,000.0	$ 26,006,000	$ 0	$ 0
Remaining repurchase amount \| $			$ 124,000,000.0	$ 124,000,000.0
Chief Executive Officer \| Joint Share Ownership Plan
Class of Stock [Line Items]
Shares subscribed (shares)	565,630
Voting ordinary shares
Class of Stock [Line Items]
Ordinary shares, par value (dollars per share) \| $ / shares			$ 1.00	$ 1.00	$ 1.00
Number of votes \| vote			1	1
Non-voting ordinary shares
Class of Stock [Line Items]
Ordinary shares, par value (dollars per share) \| $ / shares			$ 1.00	$ 1.00	$ 1.00
KaylaRe
Class of Stock [Line Items]
Number of Enstar ordinary shares issued (shares)		2,007,017
KaylaRe \| Ordinary Shares
Class of Stock [Line Items]
Number of Enstar ordinary shares issued (shares)		1,501,778

Shareholders' Equity - Non-Voting Shares (Details) - shares	May 14, 2018	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2017
Class of Stock [Line Items]
Ordinary shares, issued (shares)		22,085,232	21,511,505
Ordinary shares, outstanding (shares)		22,085,232	21,511,505
Series C non-voting convertible ordinary shares
Class of Stock [Line Items]
Conversion ratio, issued upon conversion (shares)				1
Aggregate voting power of Company's issued share capital (percent) (not to exceed)				0.01%
Ordinary shares, issued (shares)		2,599,672	2,599,672
Ordinary shares, outstanding (shares)		2,599,672	2,599,672
Common Class B
Class of Stock [Line Items]
Ordinary shares, issued (shares)		0
Ordinary shares, outstanding (shares)		0
Common Class D
Class of Stock [Line Items]
Ordinary shares, issued (shares)		0
Ordinary shares, outstanding (shares)		0
Common Class E
Class of Stock [Line Items]
Ordinary shares, issued (shares)		910,010	910,010
Ordinary shares, outstanding (shares)		910,010	910,010
KaylaRe
Class of Stock [Line Items]
Number of Enstar Ordinary shares issued (in shares)	2,007,017
Common Class E \| KaylaRe
Class of Stock [Line Items]
Number of Enstar Ordinary shares issued (in shares)	505,239

Shareholders' Equity - Warrants (Details) - Common Class C	Dec. 31, 2020 $ / shares shares
Class of Stock [Line Items]
Warrants outstanding (shares) \| shares	175,901
Warrants, exercise price (dollars per share) \| $ / shares	$ 115.00

Shareholders' Equity - Preferred Shares (Details) $ / shares in Units, $ in Millions			12 Months Ended
	Nov. 21, 2018 USD ($) $ / shares shares	Jun. 28, 2018 USD ($) $ / shares shares	Dec. 31, 2020 $ / shares shares	Dec. 31, 2019 $ / shares shares
Class of Stock [Line Items]
Preferred shares, par value (dollars per share)			$ 1.00	$ 1.00
Series C Preferred Shares
Class of Stock [Line Items]
Preferred shares, issued (shares) \| shares			388,571	388,571
Preferred shares, liquidation preference (dollars per share)			$ 0.001
Series D Preferred Stock
Class of Stock [Line Items]
Preferred shares, issued (shares) \| shares			16,000	16,000
Dividend rate			7.00%
Series E Preferred Shares
Class of Stock [Line Items]
Preferred shares, issued (shares) \| shares			4,400	4,400
Dividend rate			7.00%
Public Stock Offering \| Series D Preferred Stock
Class of Stock [Line Items]
Preferred shares, liquidation preference (dollars per share)		$ 25,000
Consideration received on sale of stock \| $		$ 400.0
Number of shares issued (shares) \| shares		16,000
Dividend rate		7.00%
Depositary shares equivalent (shares) \| shares		16,000,000
Depositary share, interest in preferred share		0.001
Preferred shares, par value (dollars per share)		$ 1.00
Liquidation preference per depositary share (dollars per share)		$ 25.00
Public Stock Offering \| Series E Preferred Shares
Class of Stock [Line Items]
Preferred shares, liquidation preference (dollars per share)	$ 25,000
Consideration received on sale of stock \| $	$ 110.0
Number of shares issued (shares) \| shares	4,400
Dividend rate	7.00%
Depositary shares equivalent (shares) \| shares	4,400,000
Depositary share, interest in preferred share	0.001
Preferred shares, par value (dollars per share)	$ 1.00
Liquidation preference per depositary share (dollars per share)	$ 25.00

Shareholders' Equity - Dividends on Preferred Shares (Details) - USD ($) $ in Thousands				12 Months Ended
	Feb. 05, 2021	Nov. 21, 2018	Jun. 28, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Total dividends paid				$ 35,700	$ 35,914	$ 12,133
Series D Preferred Shares
Class of Stock [Line Items]
Dividend rate				7.00%
Total dividends paid				$ 28,000	28,000	$ 12,100
Series E Preferred Shares
Class of Stock [Line Items]
Dividend rate				7.00%
Total dividends paid				$ 7,700	$ 7,900
Public Stock Offering \| Series D Preferred Shares
Class of Stock [Line Items]
Dividend rate			7.00%
Public Stock Offering \| Series E Preferred Shares
Class of Stock [Line Items]
Dividend rate		7.00%
LIBOR \| Public Stock Offering \| Series D Preferred Shares
Class of Stock [Line Items]
Basis spread on variable rate			4.015%
Subsequent Event \| Series D Preferred Shares
Class of Stock [Line Items]
Total dividends paid	$ 7,000
Subsequent Event \| Series E Preferred Shares
Class of Stock [Line Items]
Total dividends paid	$ 1,900

Shareholders' Equity - Changes in AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of year	$ 4,856,351
Unrealized gains (losses) on fixed income available-for-sale investments arising during the year	104,924	$ 2,896	$ (2,284)
Reclassification adjustment for net realized (gains) losses included in net earnings	(18,033)	(3,894)	63
Change in currency translation adjustment	(2,103)	(2,428)	(202)
Decrease in defined benefit pension liability	1,152	42	2,156
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(509)	0	0
Reclassification to earnings on disposal of subsidiary	(11,822)
Total other comprehensive income (loss)	73,609	(3,384)	(267)
Balance, end of year	6,688,004	4,856,351
Unrealized gains (losses) on fixed income available-for-sale investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Unrealized gains (losses) on fixed income available-for-sale investments arising during the year	104,924	2,896	(2,284)
Reclassification adjustment for net realized (gains) losses included in net earnings	(18,033)	(3,894)	63
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(509)
Reclassification to earnings on disposal of subsidiary	(11,856)
Total other comprehensive income (loss)	74,526	(998)	(2,221)
Unrealized gains (losses) on available-for-sale investments, Noncontrolling interests
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive (income) loss attributable to RNCI	(1,518)	125	222
Unrealized gains (losses) on available-for-sale investments, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of year	(432)	441	2,440
Total other comprehensive income (loss)	73,008	(873)	(1,999)
Balance, end of year	72,576	(432)	441
Cumulative Currency Translation Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Change in currency translation adjustment	(2,103)	(2,428)	(202)
Reclassification to earnings on disposal of subsidiary	34
Total other comprehensive income (loss)	(2,069)	(2,428)	(202)
Cumulative current translation adjustment, Noncontrolling interests
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive (income) loss attributable to RNCI	1,397	(10)	17
Cumulative current translation adjustment, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of year	8,548	10,986	11,171
Total other comprehensive income (loss)	(672)	(2,438)	(185)
Balance, end of year	7,876	8,548	10,986
Defined benefit pension liability, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of year	(945)	(987)	(3,143)
Decrease in defined benefit pension liability	1,152	42	2,156
Balance, end of year	207	(945)	(987)
Defined Benefit Pension Liability
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Decrease in defined benefit pension liability	1,152	42	2,156
Reclassification to earnings on disposal of subsidiary	0
Total other comprehensive income (loss)	1,152	42	2,156
Defined benefit pension liability, Noncontrolling interests
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive (income) loss attributable to RNCI	0	0	0
Accumulated Other Comprehensive Income, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of year	7,171	10,440	10,468
Balance, end of year	80,659	7,171	10,440
Accumulated Other Comprehensive Income
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Total other comprehensive income (loss)	73,609	(3,384)	(267)
Accumulated Other Comprehensive Income, Noncontrolling interests
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive (income) loss attributable to RNCI	$ (121)	$ 115	$ 239

Shareholders' Equity - Tax Effect (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax Amount	$ 79,174
Tax (Expense) Benefit	(5,565)
Reclassification adjustment for net realized (gains) losses included in net earnings	(18,033)	$ (3,894)	$ 63
Total other comprehensive income (loss)	73,609	(3,384)	(267)
Unrealized gains (losses) on fixed income available-for-sale investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before reclassifications and tax	115,610
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(499)
Reclassification adjustment for net realized (gains) losses included in net earnings	(19,766)
Reclassification to earnings on disposal of subsidiary	(15,008)
Before reclassifications, tax	(10,686)
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(10)
Reclassification adjustment for net realized (gains) losses included in net earnings	1,733
Reclassification to earnings on disposal of subsidiary	3,152
Before reclassifications, net of tax amount	104,924
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(509)
Reclassification adjustment for net realized (gains) losses included in net earnings	(18,033)	(3,894)	63
Reclassification to earnings on disposal of subsidiary	(11,856)
Total other comprehensive income (loss)	74,526	(998)	(2,221)
Cumulative Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before reclassifications and tax	(2,294)
Reclassification to earnings on disposal of subsidiary	34
Before reclassifications, tax	191
Reclassification to earnings on disposal of subsidiary	0
Before reclassifications, net of tax amount	(2,103)
Reclassification to earnings on disposal of subsidiary	34
Total other comprehensive income (loss)	(2,069)	(2,428)	(202)
Defined Benefit Pension Liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before reclassifications and tax	1,097
Before reclassifications, tax	55
Before reclassifications, net of tax amount	1,152
Total other comprehensive income (loss)	$ 1,152	$ 42	$ 2,156

Shareholders' Equity - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net realized and unrealized gains (losses)	$ 803,467	$ 500,005	$ 967,608	$ (629,061)	$ 153,477	$ 145,060	$ 260,669	$ 452,760	$ 1,642,019	$ 1,011,966	$ (407,532)
Net earnings from discontinued operations, net of income taxes	15,441	4,031	(1,152)	(2,069)	(4,666)	7,916	(3,943)	8,068	16,251	7,375	1,489
Income tax (expense)	1,468	(13,915)	(16,652)	5,272	12,893	(13,465)	(7,698)	(4,102)	(23,827)	(12,372)	3,689
NET EARNINGS (LOSS)	$ 834,655	$ 645,850	$ 787,486	$ (540,618)	$ 197,864	$ 126,559	$ 238,054	$ 365,742	1,727,373	928,219	(212,272)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
NET EARNINGS (LOSS)									30,364	3,894	(63)
Reclassification out of Accumulated Other Comprehensive Income \| Unrealized gains (losses) on fixed income available-for-sale investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net realized and unrealized gains (losses)									18,682	3,894	(63)
Net earnings from discontinued operations, net of income taxes									16,591	0	0
Total before tax									35,273	3,894	(63)
Income tax (expense)									(4,875)	0	0
NET EARNINGS (LOSS)									30,398	3,894	(63)
Reclassification out of Accumulated Other Comprehensive Income \| Cumulative Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net earnings from discontinued operations, net of income taxes									$ (34)	$ 0	$ 0

Amount after tax of income (loss) from a discontinued operation including the portion attributable to the noncontrolling interest. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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Reference 20: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 55
-Paragraph 4K
-URI http://asc.fasb.org/extlink&oid=120409616&loc=SL4591552-111686

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22658-107794

Earnings Per Share - Comparison of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net earnings (loss) from continuing operations									$ 1,711,810	$ 897,825	$ (163,232)
Net earnings from discontinued operations									7,534	4,350	878
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$ 822,599	$ 615,013	$ 798,553	$ (516,821)	$ 193,839	$ 117,743	$ 231,842	$ 358,751	$ 1,719,344	$ 902,175	$ (162,354)
Denominator:
Weighted-average ordinary shares outstanding — basic (shares)									21,551,408	21,482,617	20,698,310
Effect of dilutive securities:
Share-based compensation plans (shares)									208,293	227,878	129,746
Warrants (shares)									58,593	64,571	76,120
Weighted-average ordinary shares outstanding - diluted (shares)									21,818,294	21,775,066	20,904,176
Basic:
Net earnings (loss) from continuing operations (dollars per share)	$ 37.91	$ 28.39	$ 37.06	$ (23.93)	$ 9.15	$ 5.26	$ 10.90	$ 16.49	$ 79.43	$ 41.80	$ (7.89)
Net earnings from discontinued operations (dollars per share)	0.33	0.11	(0.03)	(0.05)	(0.13)	0.22	(0.11)	0.22	0.35	0.20	0.05
Net earnings (loss) per ordinary share (dollars per share)	38.24	28.50	37.03	(23.98)	9.02	5.48	10.79	16.71	79.78	42.00	(7.84)
Diluted:
Net earnings (loss) from continuing operations (dollars per share)	37.47	28.13	36.68	(23.93)	9.02	5.21	10.81	16.35	78.45	41.23	(7.89)
Net earnings from discontinued operations (dollars per share)	0.32	0.11	(0.03)	(0.05)	(0.13)	0.21	(0.11)	0.22	0.35	0.20	0.05
Net earnings (loss) per ordinary share (dollars per share)	$ 37.79	$ 28.24	$ 36.65	$ (23.98)	$ 8.89	$ 5.42	$ 10.70	$ 16.57	$ 78.80	$ 41.43	$ (7.84)

Share-Based Compensation and Pensions - Compensation Costs for Share-based Compensation Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	$ 27,745	$ 37,999	$ 10,670
Tax benefit	2,700	2,900	1,900
Restricted shares and restricted share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	8,286	6,564	7,641
Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	12,678	23,582	1,968
Cash-settled stock appreciation rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	215	2,575	(3,316)
Employee share purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	339	411	430
Joint share ownership plan expense \| Employee share purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	4,296	0
Northshore/Atrium incentive plan \| Time-based restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	971	3,652	2,792
StarStone incentive plan \| Time-based restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	(223)	223	0
Deferred compensation and ordinary share plan for non-employee directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation and ordinary share plan for non-employee directors	$ 1,183	$ 992	$ 1,155

Share-Based Compensation and Pensions - Restricted Shares and Restricted Share Units (Details) - Restricted shares and restricted share units - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Number of Shares
Nonvested — January 1 (shares)	64,572
Granted (shares)	70,012
Vested (shares)	(38,961)
Forfeited (shares)	(373)
Nonvested — December 31 (shares)	95,250
Weighted-Average Share Price
Nonvested - January 1 (dollars per share)	$ 180.49
Granted (dollars per share)	152.28
Vested (dollars per share)	174.93
Forfeited (dollars per share)	177.73
Nonvested - December 31 (dollars per share)	$ 161.60
Unrecognized compensation cost	$ 7.9
Unrecognized compensation cost, period of recognition	2 years 25 days

Share-Based Compensation and Pensions - Performance Share Units (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended				24 Months Ended	48 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2020
Performance share units, FDBVPS
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)						261,725
Forfeited (shares)						(28,721)
Estimated Change in Multiplier (shares)						45,680
Vested (shares)						(151,838)
Unnvested Units (shares)	126,846				126,846	126,846	126,846
Number of Shares
Granted (shares)						261,725
Increase for above target vest (shares)						45,680
Vested (shares)						(151,838)
Forfeited (shares)						(28,721)
Nonvested — December 31 (shares)	126,846				126,846	126,846
Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
PSU's Granted at Target (shares)	98,099
Forfeited (shares)	(7,442)
Estimated Change in Multiplier (shares)	25,850
Vested (shares)	(153,469)
Unnvested Units (shares)	169,987	206,949			169,987	169,987	169,987
Performance Criteria: Average Annual Operating ROE
Unrecognized compensation cost							$ 14.4
Unrecognized compensation cost, period of recognition	1 year 10 months 24 days
Number of Shares
Nonvested — January 1 (shares)	206,949
Granted (shares)	98,099
Increase for above target vest (shares)	25,850
Vested (shares)	(153,469)
Forfeited (shares)	(7,442)
Nonvested — December 31 (shares)	169,987	206,949			169,987	169,987
Weighted-Average Share Price
Nonvested - January 1 (dollars per share)	$ 185.61
Granted (dollars per share)	167.94
Increase for above target vest (dollars per share)	179.71
Vested (dollars per share)	187.24
Forfeited (dollars per share)	146.76
Nonvested - December 31 (dollars per share)	$ 174.10	$ 185.61			$ 174.10	$ 174.10
Performance share units, Average Operating ROE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)					40,868
Forfeited (shares)					(3,907)
Estimated Change in Multiplier (shares)					7,811
Vested (shares)					(1,631)
Unnvested Units (shares)	43,141				43,141	43,141	43,141
Number of Shares
Granted (shares)					40,868
Increase for above target vest (shares)					7,811
Vested (shares)					(1,631)
Forfeited (shares)					(3,907)
Nonvested — December 31 (shares)	43,141				43,141	43,141
Performance Target One \| Performance share units \| Minimum
Performance Criteria: Average Annual Operating ROE
Share settlement percentage	100.00%
Performance Target One \| Performance share units \| Maximum
Performance Criteria: Average Annual Operating ROE
Share settlement percentage	150.00%
Performance Target Two \| Performance share units \| Minimum
Performance Criteria: Average Annual Operating ROE
Share settlement percentage	60.00%
Performance Target Two \| Performance share units \| Maximum
Performance Criteria: Average Annual Operating ROE
Share settlement percentage	100.00%
2017 Awards \| Performance share units, FDBVPS \| Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)				36,321
Forfeited (shares)				(12,267)
Estimated Change in Multiplier (shares)				9,527
Vested (shares)				(33,581)
Unnvested Units (shares)	0				0	0	0
Performance Criteria: Change in FDBVPS (3 year)
Threshold	20.00%
Target	30.00%
Maximum	40.00%
Performance Multiplier Levels Per Award Agreements
Threshold	50.00%
Target	100.00%
Maximum	150.00%
Performance Criteria: Average Annual Operating ROE
Performance multiplier	139.00%	139.00%	50.00%
Number of Shares
Granted (shares)				36,321
Increase for above target vest (shares)				9,527
Vested (shares)				(33,581)
Forfeited (shares)				(12,267)
Nonvested — December 31 (shares)	0				0	0
2017 Awards \| Performance share units, FDBVPS \| Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)				91,875
Forfeited (shares)				0
Estimated Change in Multiplier (shares)				18,100
Vested (shares)				(109,975)
Unnvested Units (shares)	0				0	0	0
Performance Criteria: Change in FDBVPS (3 year)
Threshold	30.30%
Target	35.65%
Maximum	41.00%
Performance Multiplier Levels Per Award Agreements
Threshold	50.00%
Target	100.00%
Maximum	150.00%
Performance Criteria: Average Annual Operating ROE
Performance multiplier	120.00%	120.00%	50.00%
Number of Shares
Granted (shares)				91,875
Increase for above target vest (shares)				18,100
Vested (shares)				(109,975)
Forfeited (shares)				0
Nonvested — December 31 (shares)	0				0	0
2018 Awards \| Performance share units, FDBVPS
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)			39,682
Forfeited (shares)			(12,545)
Estimated Change in Multiplier (shares)			10,218
Vested (shares)			(6,700)
Unnvested Units (shares)	30,655				30,655	30,655	30,655
Performance Criteria: Change in FDBVPS (3 year)
Threshold	25.00%
Target	32.50%
Maximum	40.00%
Performance Multiplier Levels Per Award Agreements
Threshold	50.00%
Target	100.00%
Maximum	150.00%
Performance Criteria: Average Annual Operating ROE
Performance multiplier	150.00%	100.00%	50.00%
Number of Shares
Granted (shares)			39,682
Increase for above target vest (shares)			10,218
Vested (shares)			(6,700)
Forfeited (shares)			(12,545)
Nonvested — December 31 (shares)	30,655				30,655	30,655
2019 Awards \| Performance share units, FDBVPS
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)		18,308
Forfeited (shares)		(1,758)
Estimated Change in Multiplier (shares)		7,835
Vested (shares)		(881)
Unnvested Units (shares)	23,504				23,504	23,504	23,504
Performance Criteria: Change in FDBVPS (3 year)
Threshold	20.00%
Target	30.00%
Maximum	40.00%
Performance Multiplier Levels Per Award Agreements
Threshold	60.00%
Target	100.00%
Maximum	150.00%
Number of Shares
Granted (shares)		18,308
Increase for above target vest (shares)		7,835
Vested (shares)		(881)
Forfeited (shares)		(1,758)
Nonvested — December 31 (shares)	23,504				23,504	23,504
2019 Awards \| Performance share units, FDBVPS \| Tranche One
Performance Criteria: Average Annual Operating ROE
Performance multiplier	150.00%	100.00%
2019 Awards \| Performance share units, Average Operating ROE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)		18,308
Forfeited (shares)		(1,756)
Estimated Change in Multiplier (shares)		7,811
Vested (shares)		(930)
Unnvested Units (shares)	23,433				23,433	23,433	23,433
Performance Multiplier Levels Per Award Agreements
Threshold	60.00%
Target	100.00%
Maximum	150.00%
Performance Criteria: Average Annual Operating ROE
Threshold	9.60%
Target	12.00%
Maximum	14.40%
Number of Shares
Granted (shares)		18,308
Increase for above target vest (shares)		7,811
Vested (shares)		(930)
Forfeited (shares)		(1,756)
Nonvested — December 31 (shares)	23,433				23,433	23,433
2019 Awards \| Performance share units, Average Operating ROE \| Tranche Two
Performance Criteria: Average Annual Operating ROE
Performance multiplier	150.00%	100.00%
2020 Awards \| Performance share units, FDBVPS \| Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)	22,591
Forfeited (shares)	(2,151)
Estimated Change in Multiplier (shares)	0
Vested (shares)		(701)
Unnvested Units (shares)	19,739				19,739	19,739	19,739
Performance Criteria: Change in FDBVPS (3 year)
Threshold	25.00%
Target	32.50%
Maximum	40.00%
Performance Multiplier Levels Per Award Agreements
Threshold	60.00%
Target	100.00%
Maximum	150.00%
Performance Criteria: Average Annual Operating ROE
Performance multiplier	100.00%
Number of Shares
Granted (shares)	22,591
Increase for above target vest (shares)	0
Vested (shares)		(701)
Forfeited (shares)	(2,151)
Nonvested — December 31 (shares)	19,739				19,739	19,739
2020 Awards \| Performance share units, FDBVPS \| Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)	52,948
Forfeited (shares)	0
Estimated Change in Multiplier (shares)	0
Vested (shares)		0
Unnvested Units (shares)	52,948				52,948	52,948	52,948
Performance Criteria: Change in FDBVPS (3 year)
Threshold	33.10%
Target	36.80%
Target +	44.30%
Maximum	52.10%
Performance Multiplier Levels Per Award Agreements
Threshold	50.00%
Target	100.00%
Target +	150.00%
Maximum	200.00%
Number of Shares
Granted (shares)	52,948
Increase for above target vest (shares)	0
Vested (shares)		0
Forfeited (shares)	0
Nonvested — December 31 (shares)	52,948				52,948	52,948
2020 Awards \| Performance share units, FDBVPS \| Tranche Three
Performance Criteria: Average Annual Operating ROE
Performance multiplier	100.00%
2020 Awards \| Performance share units, Average Operating ROE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)	22,560
Forfeited (shares)	(2,151)
Estimated Change in Multiplier (shares)	0
Vested (shares)	(701)
Unnvested Units (shares)	19,708				19,708	19,708	19,708
Performance Multiplier Levels Per Award Agreements
Threshold	60.00%
Target	100.00%
Maximum	150.00%
Performance Criteria: Average Annual Operating ROE
Threshold	9.60%
Target	12.00%
Maximum	14.40%
Number of Shares
Granted (shares)	22,560
Increase for above target vest (shares)	0
Vested (shares)	(701)
Forfeited (shares)	(2,151)
Nonvested — December 31 (shares)	19,708				19,708	19,708
2020 Awards \| Performance share units, Average Operating ROE \| Tranche Two
Performance Criteria: Average Annual Operating ROE
Performance multiplier	100.00%

Share-Based Compensation and Pensions - Cash-Settled Stock Appreciation Rights (Detail) - Cash-settled stock appreciation rights - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of SARs
Balance, beginning of year, Number of SARs (shares)	89,227
Exercised, Number of SARs (shares)	(12,793)
Balance, end of year, Number of SARs (shares)	76,434	89,227
Weighted-Average Exercise Price of SARs
Balance, beginning of year, Weighted Average Exercise Price of SARs (dollars per share)	$ 143.33
Exercised, Weighted Average Exercise Price of SARs (dollars per share)	136.94
Balance, end of year, Weighted Average Exercise Price of SARs (dollars per share)	$ 144.40	$ 143.33
Balance, end of year, Weighted Average Remaining Contractual Term (in years)	1 year 10 months 24 days
Balance, end of year, Aggregate Intrinsic Value	$ 4,623,000
Closing price per share, ordinary shares (dollars per share)	$ 204.89
Unrecognized compensation cost	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Weighted-average fair value per SAR (dollars per share)	$ 78.47	$ 76.03	$ 45.85
Weighted-average volatility	49.43%	19.75%	18.94%
Weighted-average risk-free interest rate	0.15%	1.64%	2.72%
Dividend yield	0.00%	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise period	4 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise period	10 years

Share-Based Compensation and Pensions - Joint Share Ownership Plan (Details) - USD ($) $ / shares in Units, $ in Millions			12 Months Ended
	Jan. 20, 2023	Jan. 21, 2020	Dec. 31, 2020
Joint Share Ownership Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (shares)		565,630
Hurdle price per share (dollars per share)		$ 266.00
Shares issued, price per share (dollars per share)		205.89
Percentage of award subject to performance condition			20.00%
Grant date fair value (dollars per share)		$ 24.13
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Weighted-average volatility			18.66%
Weighted-average risk-free interest rate			1.55%
Dividend yield			0.00%
Unrecognized compensation cost			$ 9.4
Unrecognized compensation cost, period of recognition			2 years 1 month 6 days
Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (shares)		565,630
Chief Executive Officer \| Joint Share Ownership Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		3 years
Grant date fair value		$ 13.6
Scenario, Forecast \| Joint Share Ownership Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volume weighted average price per share, days	10 days
Consecutive trading days	10 days

Share-Based Compensation and Pensions - Other Share-Based Compensation Plans (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Northshore/Atrium incentive plan \| Minimum \| Time-based restricted shares
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period	2 years
Northshore/Atrium incentive plan \| Maximum \| Time-based restricted shares
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period	3 years
StarStone incentive plan \| Minimum \| Time-based restricted shares
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period	2 years
StarStone incentive plan \| Maximum \| Time-based restricted shares
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period	3 years
Deferred compensation and ordinary share plan for non-employee directors \| Director \| Share-based compensation plans
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Restricted share units credited to the accounts of non-employee directors (shares)	7,204	5,976	5,691
Joint share ownership plan expense \| Employee share purchase plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Discount rate from market price	15.00%
Maximum subscription rate	15.00%
Stock issued to employees (shares)	16,914	15,269	14,183

Share-Based Compensation and Pensions - Pension Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plans	$ 11,791	$ 11,798	$ 11,434
Defined benefit plan	2,975	684	2,243
Total pension expense	14,766	12,482	$ 13,677
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, unfunded liability	6,900	8,900
Accrued liability, defined benefit plan	$ 6,900	$ 8,900

Income Taxation - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Bermuda income taxes, statutory rate	0.00%	0.00%	0.00%
Valuation allowance	$ 118,229,000	$ 117,390,000
Increase (decrease) in valuation allowance	800,000
Unrecognized tax benefits	0	0	$ 0
Accrued interest and penalties related to unrecognized tax benefits	$ 0	$ 0	$ 0

Income Taxation - Earnings before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Domestic (Bermuda)	$ 1,503,505	$ 576,338	$ (232,743)
Foreign	231,444	356,878	15,293
Total earnings (loss) before income taxes attributable to continuing operations	$ 1,734,949	$ 933,216	$ (217,450)

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
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-Subparagraph (c)
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(15))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Income Taxation - Tax Expense for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Domestic (Bermuda)									$ 0	$ 0	$ 0
Foreign									15,232	16,330	(917)
Total current tax expense									15,232	16,330	(917)
Deferred:
Domestic (Bermuda)									0	0	0
Foreign									8,595	(3,958)	(2,772)
Total deferred tax expense									8,595	(3,958)	(2,772)
Total income tax expense (benefit) attributable to continuing operations	$ (1,468)	$ 13,915	$ 16,652	$ (5,272)	$ (12,893)	$ 13,465	$ 7,698	$ 4,102	$ 23,827	$ 12,372	$ (3,689)

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Income Taxation - Reconciliation of Earnings before Income Taxes Computed by Applying Effective Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Earnings (loss) before income taxes	$ 1,734,949	$ 933,216	$ (217,450)
Bermuda income taxes at statutory rate	0.00%	0.00%	0.00%
Foreign income tax rate differential	1.20%	8.60%	0.60%
Change in valuation allowance	0.10%	(7.20%)	(1.80%)
U.S. base erosion and anti-abuse tax	0.00%	0.30%	(0.30%)
Other	0.10%	(0.40%)	3.20%
Effective tax rate	1.40%	1.30%	1.70%

Income Taxation - Components of Deferred Tax Assets and Deferred Tax Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 141,459	$ 144,609
Insurance reserves	22,238	7,535
Unearned premiums	68	151
Provisions for bad debt	407	6,172
Defendant asbestos and environmental liabilities	121,006	140,000
Other deferred tax assets	16,696	3,230
Deferred tax assets	301,874	301,697
Valuation allowance	(118,229)	(117,390)
Deferred tax assets, net of valuation allowance	183,645	184,307
Deferred tax liabilities:
Unrealized gains on investments	(20,185)	(14,079)
Lloyd's underwriting profit taxable in future periods	(15,555)	(8,852)
Deferred policy acquisition cost	0	(8,267)
Other deferred tax liabilities	(9,242)	(13,390)
Deferred tax liabilities	(44,982)	(44,588)
Net deferred tax asset	$ 138,663	$ 139,719

Income Taxation - Deferred Tax Ending Balance (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Net Deferred Tax Asset	$ 138,663	$ 139,719
United States
Segment Reporting Information [Line Items]
Net Deferred Tax Asset	156,730	154,700
United Kingdom
Segment Reporting Information [Line Items]
Net Deferred Tax Liability	(18,095)	(16,074)
Other
Segment Reporting Information [Line Items]
Net Deferred Tax Asset	$ 28	$ 1,093

Income Taxation - Net Operating Loss Carryforwards (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Tax effect	$ 141,459	$ 144,609
Foreign Tax Authority \| United States
Operating Loss Carryforwards [Line Items]
Loss Carryforwards	428,732
Tax effect	90,034
Foreign Tax Authority \| United Kingdom
Operating Loss Carryforwards [Line Items]
Loss Carryforwards	185,230
Tax effect	35,194
Foreign Tax Authority \| Luxembourg
Operating Loss Carryforwards [Line Items]
Loss Carryforwards	17,200
Tax effect	4,300
Foreign Tax Authority \| Other
Operating Loss Carryforwards [Line Items]
Loss Carryforwards	48,683
Tax effect	$ 11,931

Related Party Transactions - Stone Point Capital LLC (Details) $ in Thousands					3 Months Ended									6 Months Ended	12 Months Ended
	Dec. 31, 2020 USD ($) director	Oct. 01, 2019 USD ($)	Apr. 01, 2019 USD ($)	Oct. 01, 2018 USD ($)	Dec. 31, 2020 USD ($) director	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Jul. 31, 2012 shares	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($) director	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jan. 01, 2021	Nov. 06, 2013 general_partner
Related Party Transaction [Line Items]
Number of newly elected board of directors \| director	5				5										5
Ownership %	47.40%				47.40%				47.40%						47.40%	47.40%
Assumed business															$ 2,186,024	$ 1,586,307	$ 1,772,104
Adverse development cover		$ 59,000
Redeemable noncontrolling interest	$ 365,436				$ 365,436				$ 438,791						365,436	438,791	458,543
Related Party, Consolidated Balance Sheet [Abstract]
Available-for-sale, at fair value	3,658,895				3,658,895				1,666,387						3,658,895	1,666,387
Equities, at fair value	846,795				846,795				726,721						846,795	726,721
Investments in funds	4,244,034				4,244,034				2,518,031						4,244,034	2,518,031
Total investments	15,256,930				15,256,930				12,619,793						15,256,930	12,619,793
Cash and cash equivalents	901,152				901,152				624,472						901,152	624,472	535,809
Other assets	925,533				925,533				1,162,955						925,533	1,162,955
Other liabilities	$ 942,905				942,905				994,584						942,905	994,584
Related Party, Consolidated Statement of Earnings [Abstract]
Net investment income					61,530	$ 72,130	$ 94,443	$ 74,714	76,847	$ 81,502	$ 74,271	$ 75,651			302,817	308,271	261,698
Net realized and unrealized gains (losses)					803,467	500,005	967,608	(629,061)	153,477	145,060	260,669	452,760			1,642,019	1,011,966	(407,532)
NET EARNINGS (LOSS)					$ 834,655	$ 645,850	787,486	$ (540,618)	197,864	$ 126,559	$ 238,054	$ 365,742			$ 1,727,373	928,219	(212,272)
Scenario, Forecast
Related Party Transaction [Line Items]
Payments to acquire investments														$ 27,000
North Bay
Related Party Transaction [Line Items]
Ownership interest held by parent	59.00%				59.00%										59.00%
Northshore
Related Party Transaction [Line Items]
Percentage of shares owned in order to designate member of board of directors	50.00%				50.00%										50.00%
Right to designate board of directors if 50% or more of shares owned \| director	1				1										1
Common shares subject to transfer restriction, term	18 months
SSHL
Related Party Transaction [Line Items]
Ownership interest held by parent	59.00%				59.00%										59.00%
Affiliated entity
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	$ 3,300,000				$ 3,300,000										$ 3,300,000
SSHL
Related Party Transaction [Line Items]
Number designated to board of directors \| director	3				3										3
Trident \| Affiliated entity
Related Party Transaction [Line Items]
Voting ordinary shares acquired (shares) \| shares													1,635,986
Number of newly elected board of directors \| general_partner																			1
Number of general partners \| general_partner																			4
Redeemable noncontrolling interest	$ 350,200				$ 350,200				420,500						$ 350,200	420,500
Related Party, Consolidated Balance Sheet [Abstract]
Equities, at fair value	77,100				77,100										77,100
StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Equities, at fair value	103,914				103,914				121,794						103,914	121,794
Total investments	1,054,873				1,054,873				1,142,446						1,054,873	1,142,446
Cash and cash equivalents	23,933				23,933				54,080						23,933	54,080
Other assets	403				403				10						403	10
Other liabilities	745				745				4,710						745	4,710
Net investment	1,078,464				1,078,464				1,191,826						1,078,464	1,191,826
Related Party, Consolidated Statement of Earnings [Abstract]
Net investment income															16,325	8,733	7,424
Net realized and unrealized gains (losses)															23,750	26,631	207
NET EARNINGS (LOSS)															40,075	35,364	7,631
Starstone
Related Party Transaction [Line Items]
Assumed business		189,400
Reinsurance premium consideration		$ 189,400
Short-term Investments
Related Party, Consolidated Balance Sheet [Abstract]
Available-for-sale, at fair value	263,795				263,795				128,335						263,795	128,335
Fixed maturity investments, trading	5,129				5,129				51,490						5,129	51,490
Short-term Investments \| StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Available-for-sale, at fair value	878				878				1,431						878	1,431
Fixed Maturities
Related Party, Consolidated Balance Sheet [Abstract]
Available-for-sale, at fair value	3,395,100				3,395,100				1,538,052						3,395,100	1,538,052
Fixed maturity investments, trading	4,594,892				4,594,892				6,143,335						4,594,892	6,143,335
Fixed Maturities \| StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Available-for-sale, at fair value	227,397				227,397				160,303						227,397	160,303
Fixed maturity investments, trading	196,086				196,086				269,131						196,086	269,131
Hedge funds
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	2,638,339				2,638,339				1,121,904						2,638,339	1,121,904
Hedge funds \| StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	19,844				19,844				18,993						19,844	18,993
Fixed income funds
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	552,541				552,541				481,039						552,541	481,039
Fixed income funds \| StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	210,017				210,017				381,449						210,017	381,449
Private equity funds
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	363,103				363,103				323,496						363,103	323,496
Private equity funds \| StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	37,262				37,262				34,858						37,262	34,858
CLO equities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	128,083				128,083				87,555						128,083	87,555
CLO equities \| StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	38,658				38,658				32,560						38,658	32,560
CLO equity funds
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	166,523				166,523				87,509						166,523	87,509
CLO equity funds \| StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	166,523				166,523				87,509						166,523	87,509
Private Debt \| StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	27,016				27,016				16,312						27,016	16,312
Real estate fund \| StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	$ 27,278				$ 27,278				$ 18,106						$ 27,278	$ 18,106
Stone Point \| Affiliated entity
Related Party Transaction [Line Items]
Voting ordinary shares acquired, percent	8.80%				8.80%										8.80%
Trident \| Scenario, Forecast
Related Party Transaction [Line Items]
Payments to acquire investments														$ 18,000
Trident \| North Bay
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners	39.30%				39.30%										39.30%
Trident \| Northshore \| Subsequent Event
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners																		76.30%
Trident \| SSHL
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners	39.30%				39.30%										39.30%
Trident \| SSHL
Related Party Transaction [Line Items]
Number designated to board of directors \| director	2				2										2
Trident \| North Bay
Related Party Transaction [Line Items]
Payments to acquire investments				$ 53,100
Dowling \| North Bay
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners	1.70%				1.70%										1.70%
Dowling \| Northshore \| Subsequent Event
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners																		1.60%
Dowling \| Core Specialty \| Subsequent Event
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners																		0.40%
Dowling \| SSHL
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners	1.70%				1.70%										1.70%
Core Specialty \| Northshore \| Subsequent Event
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners																		13.80%
North Bay \| Northshore
Related Party Transaction [Line Items]
Ownership interest held by parent	92.10%				92.10%										92.10%
North Bay \| SSHL
Related Party Transaction [Line Items]
Ownership interest held by parent	100.00%				100.00%										100.00%
North Bay Shareholders \| North Bay
Related Party Transaction [Line Items]
Payments to acquire investments			$ 48,000	$ 135,000
Mitchell International \| Affiliated entity
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	$ 26,900				$ 26,900										$ 26,900		$ 25,000
Sound Point Capital \| Affiliated entity \| Senior Loans
Related Party Transaction [Line Items]
Note receivable							$ 10,000
Term loan facility, term							2 years
Core Specialty
Related Party Transaction [Line Items]
Ownership %																		25.23%
Core Specialty \| Subsequent Event
Related Party Transaction [Line Items]
Ownership %																		25.23%

Related Party Transactions - KaylaRe (Details) - USD ($) $ in Thousands			3 Months Ended								12 Months Ended
	May 14, 2018	Dec. 15, 2016	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 13, 2018
Related Party Transaction [Line Items]
Ownership percentage			47.40%				47.40%				47.40%	47.40%
Fee income due to Enstar Limited													$ 1,453
Transactions under KaylaRe-StarStone QS:
Ceded premium earned											$ (157,826)	$ (145,483)	(166,334)
Net incurred losses and LAE			$ 76,248	$ 109,686	$ 186,692	$ 43,300	$ 48,068	$ 163,258	$ 146,554	$ 256,299	415,926	614,179	323,722
Acquisition costs			$ 38,202	$ 37,708	$ 49,067	$ 46,043	$ 78,417	$ 33,310	$ 51,081	$ 77,801	$ 171,020	$ 240,609	177,855
KaylaRe
Related Party Transaction [Line Items]
Initial capital raise		$ 620,000
KaylaRe Transactions With Starstone
Transactions under KaylaRe-StarStone QS:
Ceded premium earned													(52,651)
Net incurred losses and LAE													31,654
Acquisition costs													18,774
Affiliated entity \| KaylaRe
Transactions under KaylaRe-StarStone QS:
Total net earnings (loss)													$ (770)
KaylaRe
Related Party Transaction [Line Items]
Ownership percentage														48.20%
KaylaRe
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	2,007,017
Ordinary Shares \| KaylaRe
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	1,501,778
Ordinary Shares \| KaylaRe \| Hillhouse
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	1,204,353
Ordinary Shares \| KaylaRe \| Trident
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	285,986
Series E non-voting convertible ordinary shares \| KaylaRe
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	505,239
Series E non-voting convertible ordinary shares \| KaylaRe \| Hillhouse
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	505,239
Series E non-voting convertible ordinary shares \| KaylaRe \| Minority Shareholder
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	11,439

Related Party Transactions - Hillhouse (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Feb. 21, 2021	Dec. 31, 2019
Related Party Transaction [Line Items]
Investments in funds	$ 4,244,034		$ 2,518,031
Ownership %	47.40%		47.40%
Series C non-voting convertible ordinary shares
Related Party Transaction [Line Items]
Warrants outstanding (shares)	175,901
Warrants, exercise price (dollars per share)	$ 115.00
Affiliated entity
Related Party Transaction [Line Items]
Investments in funds	$ 3,300,000
Hillhouse Affiliates \| Affiliated entity
Related Party Transaction [Line Items]
Voting ordinary shares acquired, percent	9.40%
Economic ownership percentage	16.60%
Hillhouse
Related Party Transaction [Line Items]
Investments in funds	$ 2,734,666		$ 1,151,601
Hillhouse \| Affiliated entity
Related Party Transaction [Line Items]
Investments in funds	403,580		155,377
Increase in other investments	300,000
Management fees	394,000
Hillhouse \| Affiliated entity \| Scenario, Forecast
Related Party Transaction [Line Items]
Performance fee waived		$ 100,000
Hillhouse \| Hillhouse Affiliates \| Affiliated entity
Related Party Transaction [Line Items]
Investments in funds	$ 851,435		327,799
Hillhouse InRe Fund, L.P. \| Fixed Income Securities \| Affiliated entity
Related Party Transaction [Line Items]
Percent of funds invested	(5.00%)
Hillhouse InRe Fund, L.P. \| North American Equities \| Affiliated entity
Related Party Transaction [Line Items]
Percent of funds invested	20.00%
Hillhouse InRe Fund, L.P. \| International Equities \| Affiliated entity
Related Party Transaction [Line Items]
Percent of funds invested	67.00%
Hillhouse InRe Fund, L.P. \| Financing, Derivatives And Other Items \| Affiliated entity
Related Party Transaction [Line Items]
Percent of funds invested	18.00%
InRe Fund \| Hillhouse \| Affiliated entity
Related Party Transaction [Line Items]
Investments in funds	$ 2,365,158		918,633
Other funds \| Hillhouse \| Affiliated entity
Related Party Transaction [Line Items]
Investments in funds	$ 369,508		$ 232,968

Related Party Transactions - Monument (Details) $ in Thousands, € in Millions	3 Months Ended								12 Months Ended			39 Months Ended	51 Months Ended
	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2020 USD ($)	May 31, 2019 USD ($)	May 31, 2019 EUR (€)
Related Party Transaction [Line Items]
Investment in common and preferred shares									$ 33,000	$ 69,213	$ 155,440
Ownership percentage	47.40%				47.40%				47.40%	47.40%		47.40%	47.40%
Equity method investments	$ 832,295				$ 326,277				$ 832,295	$ 326,277		$ 326,277	$ 832,295
Earnings from equity method investments	$ 85,844	$ 149,065	$ (8,790)	$ 12,450	$ 11,722	$ 17,703	$ 17,713	$ 8,772	$ 238,569	$ 55,910	42,147
Fee income due to Enstar Limited											$ 1,453
Monument Re
Related Party Transaction [Line Items]
Investment in common and preferred shares												$ 26,600	$ 59,600
Voting ordinary shares acquired, percent	20.00%								20.00%				20.00%
Ownership percentage	23.00%				23.50%				23.00%	23.50%		23.50%	23.00%
Equity method investments	$ 193,716				$ 60,598				$ 193,716	$ 60,598		$ 60,598	$ 193,716
Earnings from equity method investments									88,300	$ 19,800
Fee income due to Enstar Limited									$ 100
Transfer Of Life Assurance Policies \| Subsidiary of Monument
Related Party Transaction [Line Items]
Policy benefits for life contracts														$ 99,100	€ 88.8
Assets related to future policy benefits														$ (101,600)	€ (91.1)

Related Party Transactions - Clear Spring (Details) - USD ($)		1 Months Ended	3 Months Ended								12 Months Ended
	Jan. 01, 2017	Dec. 31, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Capitalized amount	$ 56,000,000.0
Ownership percentage		47.40%	47.40%				47.40%				47.40%	47.40%
Sale of equity method investment		$ 12,200,000									$ 12,200,000	$ 0	$ 0
Gain on sale of equity method investment			$ 600,000
Equity method investments		832,295,000	832,295,000				$ 326,277,000				832,295,000	326,277,000
Earnings from equity method investments			85,844,000	$ 149,065,000	$ (8,790,000)	$ 12,450,000	11,722,000	$ 17,703,000	$ 17,713,000	$ 8,772,000	238,569,000	55,910,000	42,147,000
Balances under ceding quota share:
Reinsurance balances recoverable		2,089,163,000	2,089,163,000				2,181,134,000				2,089,163,000	2,181,134,000
Balances under assuming quota share:
Losses and LAE		10,593,282,000	10,593,282,000				9,868,404,000				10,593,282,000	9,868,404,000	9,048,796,000	$ 7,100,488,000
Funds held by reinsured companies		$ 635,819,000	635,819,000				475,732,000				635,819,000	475,732,000
Amounts under ceding quota share:
Net incurred losses and LAE											154,926,000	33,260,000	0
Acquisition costs			38,202,000	37,708,000	49,067,000	46,043,000	78,417,000	33,310,000	51,081,000	77,801,000	171,020,000	240,609,000	177,855,000
Transactions under assuming quota share:
Net incurred losses and loss adjustment expenses			$ 76,248,000	$ 109,686,000	$ 186,692,000	$ 43,300,000	$ 48,068,000	$ 163,258,000	$ 146,554,000	$ 256,299,000	$ 415,926,000	$ 614,179,000	323,722,000
Clear Spring
Related Party Transaction [Line Items]
Ownership percentage		0.00%	0.00%				20.00%				0.00%	20.00%
Equity method investments		$ 0	$ 0				$ 10,645,000				$ 0	$ 10,645,000
Earnings from equity method investments											$ 1,000,000.0	600,000
Clear Spring
Related Party Transaction [Line Items]
Percentage reinsured of certain businesses	25.00%
Balances under assuming quota share:
Losses and LAE							6,135,000					6,135,000
Unearned premiums							13,000					13,000
Funds held by reinsured companies							8,611,000					8,611,000
Equity method investee \| Clear Spring
Related Party Transaction [Line Items]
Ownership percentage		20.00%	20.00%								20.00%
Affiliated entity \| Clear Spring
Amounts under ceding quota share:
Acquisition costs											$ (11,000)	92,000	1,836,000
Transactions under assuming quota share:
Premium earned											(15,000)	3,749,000	7,380,000
Net incurred losses and loss adjustment expenses											1,014,000	(2,202,000)	(4,536,000)
Total income impact											3,918,000	(6,616,000)	(3,334,000)
Starstone \| Clear Spring
Related Party Transaction [Line Items]
Equity method investments		$ 0	$ 0				10,600,000				0	10,600,000
Percentage reinsured of certain businesses	33.30%
Starstone \| Equity method investee \| Clear Spring
Balances under ceding quota share:
Reinsurance balances recoverable							22,812,000					22,812,000
Prepaid reinsurance premiums							51,000					51,000
Ceded other liabilities							3,616,000					3,616,000
Ceded acquisition costs							$ 21,000					21,000
Starstone \| Affiliated entity \| Clear Spring
Amounts under ceding quota share:
Ceded premium earned											122,000	(14,994,000)	(29,520,000)
Net incurred losses and LAE											2,730,000	6,567,000	18,143,000
Acquisition costs											$ 56,000	$ 356,000	$ 7,035,000

Related Party Transactions - AmTrust (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended								12 Months Ended
	Dec. 31, 2019	Nov. 30, 2018	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Investment in common and preferred shares											$ 33,000	$ 69,213	$ 155,440
Fees and commission income													1,453
Net investment income			$ 61,530	$ 72,130	$ 94,443	$ 74,714	$ 76,847	$ 81,502	$ 74,271	$ 75,651	302,817	308,271	261,698
Net realized and unrealized gains (losses)			803,467	500,005	967,608	(629,061)	153,477	145,060	260,669	452,760	1,642,019	1,011,966	(407,532)
NET EARNINGS (LOSS)			834,655	$ 645,850	$ 787,486	$ (540,618)	197,864	$ 126,559	$ 238,054	$ 365,742	1,727,373	928,219	(212,272)
Evergreen Parent L.P. \| Affiliated entity
Related Party Transaction [Line Items]
Investment in common and preferred shares	$ 25,900	$ 200,000
Ownership of equity interest		8.50%
Fees and commission income												3,300
AmTrust \| Affiliated entity
Related Party Transaction [Line Items]
Indirect investment	$ 240,100		$ 230,300				$ 240,100				230,300	240,100
Net investment income											7,365	7,667	299
Net realized and unrealized gains (losses)											(11,183)	10,086	0
NET EARNINGS (LOSS)											$ (3,818)	$ 17,753	$ 299
AmTrust \| Affiliated entity
Related Party Transaction [Line Items]
Voting ordinary shares acquired, percent		45.00%
Evergreen Parent L.P. \| Trident Pine \| Affiliated entity
Related Party Transaction [Line Items]
Ownership of equity interest		21.80%

Related Party Transactions - Citco (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	Jun. 30, 2018	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Ownership %		47.40%				47.40%				47.40%	47.40%
Net additional subscriptions										$ 975,024	$ 794,613	$ 900,262
Investments in funds		$ 4,244,034				$ 2,518,031				4,244,034	2,518,031
Earnings from equity method investments		85,844	$ 149,065	$ (8,790)	$ 12,450	$ 11,722	$ 17,703	$ 17,713	$ 8,772	238,569	$ 55,910	$ 42,147
Affiliated entity
Related Party Transaction [Line Items]
Investments in funds		$ 3,300,000								$ 3,300,000
CTCO Holdings Limited \| Citco
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners		6.20%								6.20%
CTCO Holdings Limited \| Convertible Preferred Stock \| Citco
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners		15.40%								15.40%
Citco \| Trident \| Affiliated entity
Related Party Transaction [Line Items]
Net additional subscriptions	$ 50,000
Voting ordinary shares acquired, percent		3.40%								3.40%
Citco
Related Party Transaction [Line Items]
Ownership %						31.90%					31.90%
Investments in funds		$ 53,000				$ 51,700				$ 53,000	$ 51,700
Earnings from equity method investments										$ 2,200	$ 2,700
Citco \| Ordinary Shares
Related Party Transaction [Line Items]
Ownership %		31.90%								31.90%

Related Party Transactions - EnhanzedRe (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Equity method investments	$ 832,295				$ 326,277				$ 832,295	$ 326,277
Ownership percentage	47.40%				47.40%				47.40%	47.40%
Earnings from equity method investments	$ 85,844	$ 149,065	$ (8,790)	$ 12,450	$ 11,722	$ 17,703	$ 17,713	$ 8,772	$ 238,569	$ 55,910	$ 42,147
Balances under ceding quota share:
Reinsurance balances recoverable	2,089,163				2,181,134				2,089,163	2,181,134
Funds held	635,819				475,732				635,819	475,732
Insurance balances payables	494,412				420,546				494,412	420,546
Other assets	925,533				1,162,955				925,533	1,162,955
Amounts under ceding quota share:
Ceded premium earned									(157,826)	(145,483)	(166,334)
Net incurred losses and LAE									154,926	33,260	0
Acquisition costs	38,202	37,708	49,067	46,043	78,417	33,310	51,081	77,801	171,020	240,609	177,855
Net investment income	61,530	72,130	94,443	74,714	76,847	81,502	74,271	75,651	302,817	308,271	261,698
Net realized and unrealized gains (losses)	803,467	500,005	967,608	(629,061)	153,477	145,060	260,669	452,760	1,642,019	1,011,966	(407,532)
Fees and commission income											1,453
NET EARNINGS (LOSS)	834,655	$ 645,850	$ 787,486	(540,618)	197,864	$ 126,559	$ 238,054	$ 365,742	1,727,373	928,219	(212,272)
Non-life Run-off
Balances under ceding quota share:
Reinsurance balances recoverable	1,599,869				1,724,989				1,599,869	1,724,989
Amounts under ceding quota share:
Net incurred losses and LAE									154,926	33,260	$ 0
Enhanzed Re \| Enstar
Related Party Transaction [Line Items]
Equity method investments				$ 154,100
Ownership percentage											47.40%
Uncalled amount of investment	68,700								68,700
Enhanzed Re \| Allianz
Related Party Transaction [Line Items]
Ownership percentage											24.90%
Enhanzed Re \| Hillhouse
Related Party Transaction [Line Items]
Ownership percentage											27.70%
Enhanzed Re
Related Party Transaction [Line Items]
Equity method investments	$ 330,289				$ 182,856				$ 330,289	$ 182,856
Ownership percentage	47.40%				47.40%				47.40%	47.40%
Earnings from equity method investments									$ 147,300	$ 28,900
Enhanzed Re \| Non-life Run-off
Amounts under ceding quota share:
Net incurred losses and LAE									137,000
Enhanzed Re \| Affiliated entity
Related Party Transaction [Line Items]
Equity method investments											$ 470,000
Balances under ceding quota share:
Reinsurance balances recoverable	$ 208,379				$ 59,601				208,379	59,601
Funds held	193,981				50,089				193,981	50,089
Insurance balances payables	1,276				1,443				1,276	1,443
Other assets	$ 730				$ 1,033				730	1,033
Amounts under ceding quota share:
Ceded premium earned									(391)	0
Net incurred losses and LAE									(5,977)	0
Acquisition costs									169	73
Net investment income									(4,272)	0
Net realized and unrealized gains (losses)									(740)	0
Other income									2,617	0
Fees and commission income									572	749
NET EARNINGS (LOSS)									(8,022)	822
Change in unrealized gains (losses) on AFS investments									$ (2,729)	$ 0
Enhanzed Re \| Zurich
Related Party Transaction [Line Items]
Percentage ceded									10.00%

Related Party Disclosures - Core Specialty (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Nov. 30, 2020	Dec. 31, 2017
Related Party Transaction [Line Items]
Equity method investments	$ 832,295				$ 326,277				$ 832,295	$ 326,277
Funds held by reinsured companies	635,819				475,732				635,819	475,732
Other assets	925,533				1,162,955				925,533	1,162,955
Losses and LAE	10,593,282				9,868,404				10,593,282	9,868,404	$ 9,048,796		$ 7,100,488
Insurance and reinsurance balances payable	494,412				420,546				494,412	420,546
Other liabilities	942,905				994,584				942,905	994,584
Reinsurance balances recoverable on paid and unpaid losses	2,089,163				2,181,134				2,089,163	2,181,134
Net premiums earned	108,146	$ 161,724	$ 142,871	$ 159,351	185,336	$ 175,802	$ 190,962	$ 251,947	572,092	804,047	695,779
Net incurred losses and loss adjustment expenses									(154,926)	(33,260)	0
Acquisition costs	38,202	37,708	49,067	46,043	78,417	33,310	51,081	77,801	171,020	240,609	177,855
Fees and commission income											1,453
NET EARNINGS (LOSS)	834,655	$ 645,850	$ 787,486	$ (540,618)	$ 197,864	$ 126,559	$ 238,054	$ 365,742	1,727,373	$ 928,219	$ (212,272)
Discontinued operations, disposed of by sale \| StarStone US
Related Party Transaction [Line Items]
Consideration received	281,989								281,989			$ 235,000
Initial cash consideration received												51,500
Cash consideration received												$ 47,000
Core Specialty
Related Party Transaction [Line Items]
Equity method investments	235,000								235,000
Affiliated entity \| Core Specialty
Related Party Transaction [Line Items]
Cash consideration repayable	4,500								4,500
Core Specialty \| Affiliated entity
Related Party Transaction [Line Items]
NET EARNINGS (LOSS)									3,315
Core Specialty \| Affiliated entity \| Balances under assuming quota share, LTP and ADC reinsurances
Related Party Transaction [Line Items]
Funds held by reinsured companies	58,086								58,086
Other assets	38,846								38,846
Losses and LAE	682,637								682,637
Insurance and reinsurance balances payable	24,806								24,806
Other liabilities	5,003								5,003
Net premiums earned									76
Net incurred losses and loss adjustment expenses									(1,223)
Acquisition costs									458
Core Specialty \| Affiliated entity \| Balances under ceding reinsurances
Related Party Transaction [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	1,736								1,736
Core Specialty \| Affiliated entity \| Balances under service agreements
Related Party Transaction [Line Items]
Other assets	6,727								6,727
Other liabilities	328								328
Fees and commission income									4,004
Core Specialty \| Affiliated entity \| Balances under sale and recapitalization agreement
Related Party Transaction [Line Items]
Other liabilities	$ 4,512								$ 4,512

Dividend Restrictions and Statutory Financial Information - Parent Company Dividends (Details)	12 Months Ended
	Dec. 31, 2020
Series D Preferred Shares
Statutory Accounting Practices [Line Items]
Dividend rate	7.00%
Series E Preferred Shares
Statutory Accounting Practices [Line Items]
Dividend rate	7.00%
Bermuda
Statutory Accounting Practices [Line Items]
Target statutory capital and surplus percent	120.00%

Dividend Restrictions and Statutory Financial Information - Subsidiary Statutory Financial Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Bermuda
Statutory Accounting Practices [Line Items]
Required	$ 2,711,687	$ 2,138,395
Actual	5,565,429	4,016,663
Statutory Income	1,850,913	643,683	$ 29,486
U.K.
Statutory Accounting Practices [Line Items]
Required	803,685	837,104
Actual	1,224,208	1,532,751
Statutory Income	43,219	154,644	(52,936)
U.S.
Statutory Accounting Practices [Line Items]
Required	185,904	364,507
Actual	554,339	861,379
Statutory Income	(67,477)	121,406	(75,005)
Europe
Statutory Accounting Practices [Line Items]
Required	95,746	94,334
Actual	214,115	229,344
Statutory Income	(983)	11,816	(17,611)
Australia
Statutory Accounting Practices [Line Items]
Required	18,858	18,110
Actual	58,531	37,815
Statutory Income	$ (1,722)	$ 4,847	$ 1,761

Dividend Restrictions and Statutory Financial Information - Subsidiary Statutory Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statutory Accounting Practices [Line Items]
Restricted net assets of consolidated subsidiaries	$ 3,800.0
Bermuda
Statutory Accounting Practices [Line Items]
Minimum liquidity ratio percent (not less than)	75.00%
Minimum percentage reduction in total statutory capital without prior approval of Bermuda regulator (percent) (or more)	15.00%
Maximum percentage reduction in total statutory capital without prior approval of Bermuda regulator (percent) (or more)	25.00%
Minimum solvency requirement	$ 2,900.0	$ 1,900.0
United Kingdom
Statutory Accounting Practices [Line Items]
Minimum capital requirements	420.5	695.6
United States
Statutory Accounting Practices [Line Items]
Minimum levels of risk-based capital	362.2	488.3
Liechtenstein
Statutory Accounting Practices [Line Items]
Minimum solvency requirement	$ 97.6	$ 119.0

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2019
Concentration Risk [Line Items]
Funds held by reinsured companies	$ 635,819		$ 475,732
Renewal lease term	5 years
Termination period	1 year
Rent expense		$ 11,300
Minimum
Concentration Risk [Line Items]
Remaining lease terms	1 year
Maximum
Concentration Risk [Line Items]
Remaining lease terms	36 years
Limited Parental Guarantee
Concentration Risk [Line Items]
Total parental guarantees	$ 1,500,000		$ 1,000,000
Reinsurer concentration risk \| Reinsurance balances recoverable
Concentration Risk [Line Items]
Funds held by reinsured companies	955,000
United States
Concentration Risk [Line Items]
Exposure to government	1,400,000
Other investments
Concentration Risk [Line Items]
Commitments, unfunded	975,500
Equity Method Investments
Concentration Risk [Line Items]
Commitments, unfunded	68,700
Fixed maturity investments, trading
Concentration Risk [Line Items]
Commitments, unfunded	$ 5,000

Commitments and Contingencies - Leases - Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lease cost:
Operating lease cost	$ 12,720	$ 13,627
Short-term lease cost	246	0
Total lease cost	12,966	13,627
Sub-lease income	(553)	(542)
Total net lease cost	12,413	13,085
Other information:
Operating cash paid for amounts included in the measurement of lease liabilities	13,421	11,129
Non-cash activity: right-of-use assets relating to leases	$ 295	$ 57,536
Weighted-average remaining lease term	6 years 1 month 6 days	6 years 3 months 18 days
Weighted-average discount rate	6.50%	6.30%

Commitments and Contingencies - Leases - Balance Sheet Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Right-of-use assets	$ 32,297	$ 46,747
Current lease liabilities	7,959	11,403
Non-current lease liabilities	27,064	$ 34,785
Starstone International
Lessee, Lease, Description [Line Items]
Operating lease, impairment loss	3,500
Atrium \| Held-for-sale or disposed of by sale, not discontinued operations
Lessee, Lease, Description [Line Items]
Right-of-use asset, held-for-sale	1,000
Lease liability, held-for-sale	$ 800

Commitments and Contingencies - Leases - Operating Lease Liabilities (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 9,774
2022	8,099
2023	7,267
2024	5,561
2025	4,534
2026 and beyond	8,577
Total lease payments	43,812
Less: Imputed interest	(8,789)
Present value of lease liabilities	$ 35,023

Segment Information - Additional Information (Details)	12 Months Ended
Segment Information - Additional Information (Details)	Dec. 31, 2020 Segment
Segment Reporting [Abstract]
Number of segments	3

Segment Information - Summary of Operations by Segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Gross premiums written									$ 551,983	$ 658,653	$ 817,532
Net premiums written									432,824	545,053	654,347
Net premiums earned	$ 108,146	$ 161,724	$ 142,871	$ 159,351	$ 185,336	$ 175,802	$ 190,962	$ 251,947	572,092	804,047	695,779
Net incurred losses and LAE	(76,248)	(109,686)	(186,692)	(43,300)	(48,068)	(163,258)	(146,554)	(256,299)	(415,926)	(614,179)	(323,722)
Acquisition costs	(38,202)	(37,708)	(49,067)	(46,043)	(78,417)	(33,310)	(51,081)	(77,801)	(171,020)	(240,609)	(177,855)
Operating expenses									(295,921)	(274,835)	(274,645)
Underwriting income (loss)									(310,775)	(325,576)	(80,443)
Net investment income	61,530	72,130	94,443	74,714	76,847	81,502	74,271	75,651	302,817	308,271	261,698
Net realized and unrealized gains	803,467	500,005	967,608	(629,061)	153,477	145,060	260,669	452,760	1,642,019	1,011,966	(407,532)
Fees and commission income	14,121	10,787	10,010	7,528	9,522	6,437	6,017	6,477	42,446	28,453	35,088
Other income (losses)	33,372	48,404	(1,087)	20,443	21,703	822	8,831	5,714	101,132	37,070	34,073
Corporate expenses									(205,558)	(138,249)	(74,141)
Interest income (expense)									(59,308)	(52,541)	(25,696)
Net foreign exchange gains (losses)	(15,018)	(8,156)	(5,158)	11,939	(12,186)	13,665	2,579	3,854	(16,393)	7,912	(2,644)
EARNINGS (LOSS) BEFORE INCOME TAXES	731,902	506,669	814,080	(556,271)	177,915	114,405	231,982	353,004	1,496,380	877,306	(259,597)
Income tax benefit (expense)	1,468	(13,915)	(16,652)	5,272	12,893	(13,465)	(7,698)	(4,102)	(23,827)	(12,372)	3,689
Earnings (losses) from equity method investments	85,844	149,065	(8,790)	12,450	11,722	17,703	17,713	8,772	238,569	55,910	42,147
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	819,214	641,819	788,638	(538,549)	202,530	118,643	241,997	357,674	1,711,122	920,844	(213,761)
Net earnings from discontinued operations, net of income taxes	15,441	4,031	(1,152)	(2,069)	(4,666)	7,916	(3,943)	8,068	16,251	7,375	1,489
NET EARNINGS (LOSS)	834,655	645,850	787,486	(540,618)	197,864	126,559	238,054	365,742	1,727,373	928,219	(212,272)
Net loss attributable to noncontrolling interest	(3,131)	(21,912)	19,992	32,722	4,900	109	2,713	2,148	27,671	9,870	62,051
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	831,524	623,938	807,478	(507,896)	202,764	126,668	240,767	367,890	1,755,044	938,089	(150,221)
Dividends on preferred shares	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(9,139)	(35,700)	(35,914)	(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$ 822,599	$ 615,013	$ 798,553	$ (516,821)	$ 193,839	$ 117,743	$ 231,842	$ 358,751	1,719,344	902,175	(162,354)
Non-life Run-off
Segment Reporting Information [Line Items]
Net incurred losses and LAE									(44,995)	(51,625)	306,067
Atrium
Segment Reporting Information [Line Items]
Net incurred losses and LAE									$ (87,226)	$ (77,276)	$ (69,810)
Underwriting ratios:
Loss ratio									49.70%	47.10%	47.70%
Acquisition expense ratio									34.00%	34.70%	34.60%
Operating expense ratio									7.50%	8.80%	12.20%
Combined ratio									91.20%	90.60%	94.50%
StarStone
Segment Reporting Information [Line Items]
Net incurred losses and LAE									$ (266,738)	$ (469,240)	$ (543,080)
Underwriting ratios:
Loss ratio									83.80%	104.00%	105.40%
Acquisition expense ratio									28.50%	24.20%	23.40%
Operating expense ratio									25.80%	13.50%	19.10%
Combined ratio									138.10%	141.70%	147.90%
Operating Segments \| Non-life Run-off
Segment Reporting Information [Line Items]
Gross premiums written									$ 5,191	$ (25,069)	$ (8,910)
Net premiums written									2,987	(25,338)	(9,217)
Net premiums earned									58,695	168,496	9,427
Net incurred losses and LAE									(44,995)	(51,625)	306,067
Acquisition costs									(20,177)	(73,642)	(4,006)
Operating expenses									(200,990)	(199,756)	(158,731)
Underwriting income (loss)									(207,467)	(156,527)	152,757
Net investment income									282,048	275,236	226,287
Net realized and unrealized gains									1,627,526	968,350	(381,712)
Fees and commission income									19,462	18,293	16,466
Other income (losses)									99,940	34,809	35,978
Corporate expenses									(97,727)	(70,689)	(39,093)
Interest income (expense)									(67,195)	(62,055)	(30,616)
Net foreign exchange gains (losses)									(13,214)	9,918	2,534
EARNINGS (LOSS) BEFORE INCOME TAXES									1,643,373	1,017,335	(17,399)
Income tax benefit (expense)									(17,412)	(7,250)	3,581
Earnings (losses) from equity method investments									238,569	56,128	42,147
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS									1,864,530	1,066,213	28,329
Net earnings from discontinued operations, net of income taxes									0	0	0
NET EARNINGS (LOSS)									1,864,530	1,066,213	28,329
Net loss attributable to noncontrolling interest									1,597	(6,409)	(3,107)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR									1,866,127	1,059,804	25,222
Dividends on preferred shares									0	0	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS									1,866,127	1,059,804	25,222
Operating Segments \| Atrium
Segment Reporting Information [Line Items]
Gross premiums written									206,656	192,373	171,494
Net premiums written									183,194	172,356	153,488
Net premiums earned									175,393	164,059	146,315
Net incurred losses and LAE									(87,226)	(77,276)	(69,810)
Acquisition costs									(59,611)	(56,956)	(50,646)
Operating expenses									(13,078)	(14,452)	(17,777)
Underwriting income (loss)									15,478	15,375	8,082
Net investment income									5,542	7,049	5,686
Net realized and unrealized gains									4,165	6,195	(3,251)
Fees and commission income									22,984	10,160	18,622
Other income (losses)									131	140	162
Corporate expenses									(21,522)	(13,825)	(6,921)
Interest income (expense)									0	0	0
Net foreign exchange gains (losses)									4,327	(504)	(3,394)
EARNINGS (LOSS) BEFORE INCOME TAXES									31,105	24,590	18,986
Income tax benefit (expense)									(4,122)	(4,033)	(3,732)
Earnings (losses) from equity method investments									0	0	0
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS									26,983	20,557	15,254
Net earnings from discontinued operations, net of income taxes									0	0	0
NET EARNINGS (LOSS)									26,983	20,557	15,254
Net loss attributable to noncontrolling interest									(11,059)	(8,432)	(6,257)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR									15,924	12,125	8,997
Dividends on preferred shares									0	0	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS									15,924	12,125	8,997
Operating Segments \| StarStone
Segment Reporting Information [Line Items]
Gross premiums written									326,695	472,815	622,570
Net premiums written									233,202	379,523	478,009
Net premiums earned									318,115	451,112	515,163
Net incurred losses and LAE									(266,738)	(469,240)	(543,080)
Acquisition costs									(90,797)	(109,369)	(120,517)
Operating expenses									(81,853)	(60,627)	(98,137)
Underwriting income (loss)									(121,273)	(188,124)	(246,571)
Net investment income									27,443	34,396	27,000
Net realized and unrealized gains									10,328	31,572	(12,320)
Fees and commission income									0	0	0
Other income (losses)									3,734	329	(550)
Corporate expenses									(42,011)	(7,790)	0
Interest income (expense)									(2,110)	(475)	(103)
Net foreign exchange gains (losses)									(10,140)	(1,505)	(2,832)
EARNINGS (LOSS) BEFORE INCOME TAXES									(134,029)	(131,597)	(235,376)
Income tax benefit (expense)									(902)	(1,004)	3,892
Earnings (losses) from equity method investments									0	(218)	0
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS									(134,931)	(132,819)	(231,484)
Net earnings from discontinued operations, net of income taxes									16,251	7,375	1,489
NET EARNINGS (LOSS)									(118,680)	(125,444)	(229,995)
Net loss attributable to noncontrolling interest									37,133	24,711	71,415
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR									(81,547)	(100,733)	(158,580)
Dividends on preferred shares									0	0	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS									(81,547)	(100,733)	(158,580)
Other
Segment Reporting Information [Line Items]
Gross premiums written									13,441	18,534	32,378
Net premiums written									13,441	18,512	32,067
Net premiums earned									19,889	20,380	24,874
Net incurred losses and LAE									(16,967)	(16,038)	(16,899)
Acquisition costs									(435)	(642)	(2,686)
Operating expenses									0	0	0
Underwriting income (loss)									2,487	3,700	5,289
Net investment income									(12,216)	(8,410)	2,725
Net realized and unrealized gains									0	5,849	(10,249)
Fees and commission income									0	0	0
Other income (losses)									(2,673)	1,792	(1,517)
Corporate expenses									(44,298)	(45,945)	(28,127)
Interest income (expense)									9,997	9,989	5,023
Net foreign exchange gains (losses)									2,634	3	1,048
EARNINGS (LOSS) BEFORE INCOME TAXES									(44,069)	(33,022)	(25,808)
Income tax benefit (expense)									(1,391)	(85)	(52)
Earnings (losses) from equity method investments									0	0	0
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS									(45,460)	(33,107)	(25,860)
Net earnings from discontinued operations, net of income taxes									0	0	0
NET EARNINGS (LOSS)									(45,460)	(33,107)	(25,860)
Net loss attributable to noncontrolling interest									0	0	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR									(45,460)	(33,107)	(25,860)
Dividends on preferred shares									(35,700)	(35,914)	(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS									$ (81,160)	$ (69,021)	$ (37,993)

Segment Information - Summary of Company's Assets by Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 21,647,284	$ 19,826,099
Assets held-for-sale (Note 5)	711,278	1,474,770
Non-life Run-off \| Held-for-sale or disposed of by sale, not discontinued operations \| Arden
Segment Reporting, Asset Reconciling Item [Line Items]
Assets held-for-sale (Note 5)	95,500
Operating Segments \| Non-life Run-off
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	19,062,400	15,775,409
Operating Segments \| Atrium
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	615,778	580,405
Operating Segments \| StarStone
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	2,583,247	3,985,137
Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ (614,141)	$ (514,852)

Unaudited Condensed Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
INCOME
Net premiums earned	$ 108,146	$ 161,724	$ 142,871	$ 159,351	$ 185,336	$ 175,802	$ 190,962	$ 251,947	$ 572,092	$ 804,047	$ 695,779
Fees and commission income	14,121	10,787	10,010	7,528	9,522	6,437	6,017	6,477	42,446	28,453	35,088
Net investment income	61,530	72,130	94,443	74,714	76,847	81,502	74,271	75,651	302,817	308,271	261,698
Net realized and unrealized gains	803,467	500,005	967,608	(629,061)	153,477	145,060	260,669	452,760	1,642,019	1,011,966	(407,532)
Other income (losses)	33,372	48,404	(1,087)	20,443	21,703	822	8,831	5,714	101,132	37,070	34,073
Total income	1,020,636	793,050	1,213,845	(367,025)	446,885	409,623	540,750	792,549	2,660,506	2,189,807	619,106
EXPENSES
Net incurred losses and loss adjustment expenses	76,248	109,686	186,692	43,300	48,068	163,258	146,554	256,299	415,926	614,179	323,722
Acquisition costs	38,202	37,708	49,067	46,043	78,417	33,310	51,081	77,801	171,020	240,609	177,855
General and administrative expenses	142,394	115,828	144,830	98,427	116,780	97,365	100,676	98,263	501,479	413,084	348,786
Interest expense	16,872	15,003	14,018	13,415	13,519	14,950	13,036	11,036	59,308	52,541	25,696
Net foreign exchange (gains) losses	15,018	8,156	5,158	(11,939)	12,186	(13,665)	(2,579)	(3,854)	16,393	(7,912)	2,644
Total expenses	288,734	286,381	399,765	189,246	268,970	295,218	308,768	439,545	1,164,126	1,312,501	878,703
EARNINGS (LOSS) BEFORE INCOME TAXES	731,902	506,669	814,080	(556,271)	177,915	114,405	231,982	353,004	1,496,380	877,306	(259,597)
Income tax benefit (expense)	1,468	(13,915)	(16,652)	5,272	12,893	(13,465)	(7,698)	(4,102)	(23,827)	(12,372)	3,689
Earnings (losses) from equity method investments	85,844	149,065	(8,790)	12,450	11,722	17,703	17,713	8,772	238,569	55,910	42,147
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	819,214	641,819	788,638	(538,549)	202,530	118,643	241,997	357,674	1,711,122	920,844	(213,761)
Net earnings from discontinued operations, net of income taxes	15,441	4,031	(1,152)	(2,069)	(4,666)	7,916	(3,943)	8,068	16,251	7,375	1,489
NET EARNINGS (LOSS)	834,655	645,850	787,486	(540,618)	197,864	126,559	238,054	365,742	1,727,373	928,219	(212,272)
Net loss attributable to noncontrolling interest	(3,131)	(21,912)	19,992	32,722	4,900	109	2,713	2,148	27,671	9,870	62,051
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	831,524	623,938	807,478	(507,896)	202,764	126,668	240,767	367,890	1,755,044	938,089	(150,221)
Dividends on preferred shares	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(9,139)	(35,700)	(35,914)	(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$ 822,599	$ 615,013	$ 798,553	$ (516,821)	$ 193,839	$ 117,743	$ 231,842	$ 358,751	$ 1,719,344	$ 902,175	$ (162,354)
Basic:
Net earnings (loss) from continuing operations (dollars per share)	$ 37.91	$ 28.39	$ 37.06	$ (23.93)	$ 9.15	$ 5.26	$ 10.90	$ 16.49	$ 79.43	$ 41.80	$ (7.89)
Net earnings (loss) from discontinued operations (dollars per share)	0.33	0.11	(0.03)	(0.05)	(0.13)	0.22	(0.11)	0.22	0.35	0.20	0.05
Net earnings (loss) per ordinary share (dollars per share)	38.24	28.50	37.03	(23.98)	9.02	5.48	10.79	16.71	79.78	42.00	(7.84)
Diluted:
Net earnings (loss) from continuing operations (dollars per share)	37.47	28.13	36.68	(23.93)	9.02	5.21	10.81	16.35	78.45	41.23	(7.89)
Net earnings (loss) from discontinued operations (dollars per share)	0.32	0.11	(0.03)	(0.05)	(0.13)	0.21	(0.11)	0.22	0.35	0.20	0.05
Net earnings (loss) per ordinary share (dollars per share)	$ 37.79	$ 28.24	$ 36.65	$ (23.98)	$ 8.89	$ 5.42	$ 10.70	$ 16.57	$ 78.80	$ 41.43	$ (7.84)

Schedule I - Summary of Investments Other Than Investments in Related Parties (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	$ 10,168,005
Fair Value	10,796,331
Amount at which shown in the balance sheet	10,796,331
Equity investments	846,795	$ 726,721
Fair value of other investments in funds or companies owned by or affiliated with related parties	4,244,034	2,518,031
Stone Point
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Fixed maturity investments	18,200
Affiliated entity
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Fair value of other investments in funds or companies owned by or affiliated with related parties	3,300,000
Affiliated entity \| Trident
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Equity investments	77,100
AmTrust
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Indirect investment	230,300	$ 240,100
Equities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	444,570
Fair Value	512,557
Amount at which shown in the balance sheet	512,557
Other investments, at fair value
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	982,770
Fair Value	982,770
Amount at which shown in the balance sheet	982,770
Funds Held - Directly Managed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	5,168,869
Fair Value	5,646,955
Amount at which shown in the balance sheet	5,646,955
Funds Held - Directly Managed \| U.S. government and agency
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	219,487
Fair Value	233,050
Amount at which shown in the balance sheet	233,050
Funds Held - Directly Managed \| U.K. government
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	34,494
Fair Value	37,508
Amount at which shown in the balance sheet	37,508
Funds Held - Directly Managed \| Other government
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	321,306
Fair Value	352,026
Amount at which shown in the balance sheet	352,026
Funds Held - Directly Managed \| Corporate
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	3,353,054
Fair Value	3,749,383
Amount at which shown in the balance sheet	3,749,383
Funds Held - Directly Managed \| Municipal
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	116,588
Fair Value	132,637
Amount at which shown in the balance sheet	132,637
Funds Held - Directly Managed \| Residential mortgage-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	219,360
Fair Value	225,074
Amount at which shown in the balance sheet	225,074
Funds Held - Directly Managed \| Commercial mortgage-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	554,639
Fair Value	577,602
Amount at which shown in the balance sheet	577,602
Funds Held - Directly Managed \| Asset-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	349,941
Fair Value	339,675
Amount at which shown in the balance sheet	339,675
Available-for-sale securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	3,571,796
Fair Value	3,654,049
Amount at which shown in the balance sheet	3,654,049
Available-for-sale securities \| U.S. government and agency
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	715,527
Fair Value	717,998
Amount at which shown in the balance sheet	717,998
Available-for-sale securities \| U.K. government
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	12,494
Fair Value	13,574
Amount at which shown in the balance sheet	13,574
Available-for-sale securities \| Other government
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	142,459
Fair Value	150,127
Amount at which shown in the balance sheet	150,127
Available-for-sale securities \| Corporate
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	1,873,184
Fair Value	1,937,349
Amount at which shown in the balance sheet	1,937,349
Available-for-sale securities \| Municipal
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	28,881
Fair Value	30,032
Amount at which shown in the balance sheet	30,032
Available-for-sale securities \| Residential mortgage-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	326,268
Fair Value	328,871
Amount at which shown in the balance sheet	328,871
Available-for-sale securities \| Commercial mortgage-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	273,516
Fair Value	276,488
Amount at which shown in the balance sheet	276,488
Available-for-sale securities \| Asset-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	199,467
Fair Value	199,610
Amount at which shown in the balance sheet	199,610
Mitchell International \| Affiliated entity
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Fair value of other investments in funds or companies owned by or affiliated with related parties	$ 26,900		$ 25,000

Schedule II - Condensed Balance Sheets (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
ASSETS
Cash and cash equivalents	$ 901,152	$ 624,472	$ 535,809
Other assets	925,533	1,162,955
TOTAL ASSETS	21,647,284	19,826,099
LIABILITIES
Debt obligations (Note 15)	1,373,259	1,191,207
Other liabilities	942,905	994,584
TOTAL LIABILITIES	14,593,844	14,530,957
SHAREHOLDERS’ EQUITY (Note 17)
Treasury shares, at cost (Series C Preferred Shares 2020 and 2019: 388,571)	(421,559)	(421,559)
Joint Share Ownership Plan (voting ordinary shares, held in trust 2020: 565,630; 2019: 0)	(566)	0
Additional paid-in capital	1,836,074	1,836,778
Accumulated other comprehensive income	80,659	7,171
Retained earnings	4,647,312	2,887,892
Total Enstar Shareholders’ Equity	6,674,395	4,842,183
TOTAL LIABILITIES, REDEEMABLE NONCONTROLLING INTEREST AND SHAREHOLDERS’ EQUITY	$ 21,647,284	$ 19,826,099
Parenthetical Disclosures [Abstract]
Common shares, par value (dollars per share)	$ 1	$ 1
Ordinary shares, shares issued (shares)	22,085,232	21,511,505
Ordinary shares, outstanding (shares)	22,085,232	21,511,505
Treasury stock, preferred shares (shares)	388,571	388,571
Treasury stock, ordinary shares (shares)	565,630	0
Voting ordinary shares
SHAREHOLDERS’ EQUITY (Note 17)
Ordinary shares	$ 18,576	$ 18,002
Parenthetical Disclosures [Abstract]
Common shares, par value (dollars per share)	$ 1.00	$ 1.00
Ordinary shares, shares issued (shares)	18,575,550	18,001,823
Ordinary shares, outstanding (shares)	18,575,550	18,001,823
Series C non-voting convertible ordinary shares
SHAREHOLDERS’ EQUITY (Note 17)
Ordinary shares	$ 2,600	$ 2,600
Parenthetical Disclosures [Abstract]
Ordinary shares, shares issued (shares)	2,599,672	2,599,672
Ordinary shares, outstanding (shares)	2,599,672	2,599,672
Series E non-voting convertible ordinary shares
SHAREHOLDERS’ EQUITY (Note 17)
Ordinary shares	$ 910	$ 910
Parenthetical Disclosures [Abstract]
Ordinary shares, shares issued (shares)	910,010	910,010
Ordinary shares, outstanding (shares)	910,010	910,010
Series C Preferred Shares
SHAREHOLDERS’ EQUITY (Note 17)
Preferred shares	$ 389	$ 389
Parenthetical Disclosures [Abstract]
Preferred shares, issued (shares)	388,571	388,571
Treasury stock, preferred shares (shares)	388,571	388,571
Series D Preferred Shares
SHAREHOLDERS’ EQUITY (Note 17)
Preferred shares	$ 400,000	$ 400,000
Parenthetical Disclosures [Abstract]
Preferred shares, issued (shares)	16,000	16,000
Preferred shares, outstanding (shares)	16,000	16,000
Series E Preferred Shares
SHAREHOLDERS’ EQUITY (Note 17)
Preferred shares	$ 110,000	$ 110,000
Parenthetical Disclosures [Abstract]
Preferred shares, issued (shares)	4,400	4,400
Preferred shares, outstanding (shares)	4,400	4,400
Enstar Group Limited
ASSETS
Cash and cash equivalents	$ 7,872	$ 4,568
Balances due from subsidiaries	18,951	134,897
Investments in subsidiaries	7,887,255	6,050,197
Other assets	8,047	6,391
TOTAL ASSETS	7,922,125	6,196,053
LIABILITIES
Debt obligations (Note 15)	903,447	1,191,207
Balances due to subsidiaries	300,987	135,532
Other liabilities	43,296	27,131
TOTAL LIABILITIES	1,247,730	1,353,870
SHAREHOLDERS’ EQUITY (Note 17)
Treasury shares, at cost (Series C Preferred Shares 2020 and 2019: 388,571)	(421,559)	(421,559)
Additional paid-in capital	1,836,074	1,836,778
Accumulated other comprehensive income	80,659	7,171
Retained earnings	4,647,312	2,887,892
Total Enstar Shareholders’ Equity	6,674,395	4,842,183
TOTAL LIABILITIES, REDEEMABLE NONCONTROLLING INTEREST AND SHAREHOLDERS’ EQUITY	7,922,125	6,196,053
Enstar Group Limited \| Voting ordinary shares
SHAREHOLDERS’ EQUITY (Note 17)
Ordinary shares	18,576	18,002
Enstar Group Limited \| Series C non-voting convertible ordinary shares
SHAREHOLDERS’ EQUITY (Note 17)
Ordinary shares	2,600	2,600
Enstar Group Limited \| Series E non-voting convertible ordinary shares
SHAREHOLDERS’ EQUITY (Note 17)
Ordinary shares	910	910
Enstar Group Limited \| Series C Preferred Shares
SHAREHOLDERS’ EQUITY (Note 17)
Preferred shares	389	389
Enstar Group Limited \| Series D Preferred Shares
SHAREHOLDERS’ EQUITY (Note 17)
Preferred shares	400,000	400,000
Enstar Group Limited \| Series E Preferred Shares
SHAREHOLDERS’ EQUITY (Note 17)
Preferred shares	$ 110,000	$ 110,000

Schedule II - Condensed Statements of Earnings (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
INCOME
Net investment income	$ 61,530	$ 72,130	$ 94,443	$ 74,714	$ 76,847	$ 81,502	$ 74,271	$ 75,651	$ 302,817	$ 308,271	$ 261,698
Total income	1,020,636	793,050	1,213,845	(367,025)	446,885	409,623	540,750	792,549	2,660,506	2,189,807	619,106
EXPENSES
General and administrative expenses	142,394	115,828	144,830	98,427	116,780	97,365	100,676	98,263	501,479	413,084	348,786
Interest expense	16,872	15,003	14,018	13,415	13,519	14,950	13,036	11,036	59,308	52,541	25,696
Net foreign exchange losses (gains)	15,018	8,156	5,158	(11,939)	12,186	(13,665)	(2,579)	(3,854)	16,393	(7,912)	2,644
Total expenses	288,734	286,381	399,765	189,246	268,970	295,218	308,768	439,545	1,164,126	1,312,501	878,703
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	831,524	623,938	807,478	(507,896)	202,764	126,668	240,767	367,890	1,755,044	938,089	(150,221)
Dividends on preferred shares	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(9,139)	(35,700)	(35,914)	(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$ 822,599	$ 615,013	$ 798,553	$ (516,821)	$ 193,839	$ 117,743	$ 231,842	$ 358,751	1,719,344	902,175	(162,354)
Enstar Group Limited
INCOME
Net investment income									1,680	3,649	142
Total income									1,680	3,649	142
EXPENSES
General and administrative expenses									45,689	44,964	68,977
Interest expense									51,739	51,508	27,353
Net foreign exchange losses (gains)									(2,655)	(21,516)	7,655
Total expenses									94,773	74,956	103,985
EARNINGS (LOSSES) BEFORE EQUITY IN UNDISTRIBUTED EARNINGS OF SUBSIDIARIES									(93,093)	(71,307)	(103,843)
Equity in undistributed earnings (losses) of subsidiaries - continuing operations									1,831,886	1,002,021	(47,867)
Equity in undistributed earnings (losses) of subsidiaries - discontinued operations									16,251	7,375	1,489
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR									1,755,044	938,089	(150,221)
Dividends on preferred shares									(35,700)	(35,914)	(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS									$ 1,719,344	$ 902,175	$ (162,354)

Schedule II - Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Statement of Income Captions [Line Items]
NET EARNINGS	$ 831,524	$ 623,938	$ 807,478	$ (507,896)	$ 202,764	$ 126,668	$ 240,767	$ 367,890	$ 1,755,044	$ 938,089	$ (150,221)
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSTAR									1,828,532	934,820	(150,248)
Enstar Group Limited
Condensed Statement of Income Captions [Line Items]
NET EARNINGS									1,755,044	938,089	(150,221)
OTHER COMPREHENSIVE INCOME (LOSS) RELATING TO SUBSIDIARIES, NET OF TAX									73,488	(3,269)	(27)
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSTAR									$ 1,828,532	$ 934,820	$ (150,248)

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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