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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2019	May 07, 2019
Document Information [Line Items]
Entity Registrant Name	Enstar Group LTD
Entity Central Index Key	0001363829
Trading Symbol	ESGR
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false
Voting Ordinary Shares
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		17,971,679
Non-Voting Convertible Ordinary Shares
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		3,509,682

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
ASSETS
Trading, at fair value	$ 8,739,303
Fixed maturities, available-for-sale, at fair value (amortized cost: 2019 — $142,675; 2018 — $151,433)	146,575	$ 151,609
Funds held - directly managed	1,288,210	1,198,154
Equities, at fair value	400,420	367,125
Other investments, at fair value	2,324,345	1,957,757
Equity method investments	221,023	204,507
Total investments (Note 3 and Note 8)	11,773,687	11,242,061
Cash and cash equivalents	718,050	602,096
Restricted cash and cash equivalents	427,601	380,488
Premiums receivable	719,979	787,468
Deferred tax assets (Note 17)	9,062	10,124
Prepaid reinsurance premiums	208,558	198,990
Reinsurance balances recoverable (Note 5)	1,551,190	1,290,072
Reinsurance balances recoverable, at fair value (Note 5 and Note 8)	735,257	739,591
Funds held by reinsured companies	919,738	321,267
Deferred acquisition costs	195,733	121,101
Goodwill and intangible assets (Note 11)	218,160	218,725
Other assets	581,236	644,287
TOTAL ASSETS	18,058,251	16,556,270
LIABILITIES
Losses and loss adjustment expenses (Note 7)	7,248,229	6,535,449
Losses and loss adjustment expenses, at fair value (Note 7 and Note 8)	2,847,793	2,874,055
Policy benefits for life and annuity contracts (Note 9)	100,682	105,080
Unearned premiums	951,042	842,618
Insurance and reinsurance balances payable	455,738	388,086
Deferred tax liabilities (Note 17)	9,204	10,542
Debt obligations (Note 12)	1,103,790	861,539
Other liabilities	605,263	566,369
TOTAL LIABILITIES	13,321,741	12,183,738
COMMITMENTS AND CONTINGENCIES (Note 19)
REDEEMABLE NONCONTROLLING INTEREST (Note 13)	456,346	458,543
SHAREHOLDERS’ EQUITY (Note 14)
Treasury shares, at cost	(421,559)	(421,559)
Additional paid-in capital	1,809,107	1,804,664
Accumulated other comprehensive income	13,279	10,440
Retained earnings	2,335,028	1,976,539
Total Enstar Group Limited Shareholders’ Equity	4,267,712	3,901,933
Noncontrolling interest	12,452	12,056
TOTAL SHAREHOLDERS’ EQUITY	4,280,164	3,913,989
TOTAL LIABILITIES, REDEEMABLE NONCONTROLLING INTEREST AND SHAREHOLDERS’ EQUITY	18,058,251	16,556,270
Voting Ordinary shares (issued and outstanding 2019: 17,957,833; 2018: 17,950,315)
SHAREHOLDERS’ EQUITY (Note 14)
Ordinary shares	17,958	17,950
Non-voting convertible ordinary Series C Shares (issued and outstanding 2019 and 2018: 2,599,672)
SHAREHOLDERS’ EQUITY (Note 14)
Ordinary shares	2,600	2,600
Non-voting convertible ordinary Series E Shares (issued and outstanding 2019 and 2018: 910,010)
SHAREHOLDERS’ EQUITY (Note 14)
Ordinary shares	910	910
Series C Preferred Shares (issued and held in treasury 2019 and 2018: 388,571)
SHAREHOLDERS’ EQUITY (Note 14)
Preferred Shares	389	389
Series D Preferred Shares (issued and outstanding 2019 and 2018: 16,000)
SHAREHOLDERS’ EQUITY (Note 14)
Preferred Shares	400,000	400,000
Series E Preferred Shares (issued and outstanding 2019 and 2018: 4,400)
SHAREHOLDERS’ EQUITY (Note 14)
Preferred Shares	110,000	110,000
Short-term Investments
ASSETS
Trading, at fair value	76,060	114,116
Fixed maturity investments
ASSETS
Trading, at fair value	7,317,054	7,248,793
Fixed maturities, available-for-sale, at fair value (amortized cost: 2019 — $142,675; 2018 — $151,433)	$ 146,575	$ 151,609

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Short-term investments, available-for-sale, at fair value, amortized cost	$ 142,675	$ 151,433
Ordinary shares, par value (in dollars per share)	$ 1	$ 1
Ordinary shares issued (in shares)	21,467,515	51,459,997
Ordinary shares outstanding (in shares)	21,467,515	21,459,997
Treasury shares at cost (in shares)	388,571	388,571
Voting Ordinary Shares
Ordinary shares issued (in shares)	17,957,833	17,950,315
Ordinary shares outstanding (in shares)	17,957,833	17,950,315
Series C Non-Voting Convertible Ordinary Shares
Ordinary shares issued (in shares)	2,599,672	2,599,672
Ordinary shares outstanding (in shares)	2,599,672	2,599,672
Series E Non-Voting Convertible Ordinary Shares
Ordinary shares issued (in shares)	910,010	910,010
Ordinary shares outstanding (in shares)	910,010	910,010
Series C Preferred Shares
Preferred shares issued (in shares)	388,571	388,571
Series D Preferred Stock
Preferred shares issued (in shares)	16,000	16,000
Preferred shares outstanding (in shares)	16,000	16,000
Series E Preferred Stock
Preferred shares issued (in shares)	4,400	4,400
Preferred shares outstanding (in shares)	4,400	4,400
Fixed maturity investments
Short-term investments, available-for-sale, at fair value, amortized cost	$ 142,675	$ 151,433

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
INCOME
Net premiums earned	$ 335,287	$ 170,219
Fees and commission income	6,681	8,331
Net investment income	78,696	66,319
Net realized and unrealized gains (losses)	460,791	(143,030)
Other income	5,812	1,943
Total income	887,267	103,782
EXPENSES
Net incurred losses and loss adjustment expenses	312,404	19,534
Life and annuity policy benefits	96	(46)
Acquisition costs	93,788	30,108
General and administrative expenses	112,074	95,260
Interest expense	11,036	8,011
Net foreign exchange gains (losses)	(3,850)	5,868
Total expenses	525,548	158,735
EARNINGS (LOSS) BEFORE INCOME TAXES	361,719	(54,953)
Income tax expense	(4,749)	(172)
Earnings from equity method investments	8,772	14,697
NET EARNINGS (LOSS)	365,742	(40,428)
Net loss (earnings) attributable to noncontrolling interest	2,148	(782)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED	367,890	(41,210)
Dividends on preferred shares	(9,139)	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$ 358,751	$ (41,210)
Earnings (Loss) per ordinary share attributable to Enstar Group Limited:
Basic (in dollars per share)	$ 16.71	$ (2.12)
Diluted (in dollars per share)	$ 16.57	$ (2.12)
Weighted average ordinary shares outstanding:
Basic (in shares)	21,463,499	19,409,021
Diluted (in shares)	21,645,862	19,602,512

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
NET EARNINGS (LOSS)	$ 365,742	$ (40,428)
Other comprehensive income, net of tax:
Unrealized holding gains (losses) on fixed income available-for-sale investments arising during the period	3,663	(346)
Reclassification adjustment for net realized gains included in net earnings	61	30
Unrealized gains (losses) arising during the period, net of reclassification adjustments	3,724	(316)
Total cumulative translation adjustment	(801)	1,225
Total other comprehensive income	2,923	909
Comprehensive income (loss)	368,665	(39,519)
Comprehensive (income) loss attributable to noncontrolling interest	2,064	(756)
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED	$ 370,729	$ (40,275)

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Ordinary Shares Voting Ordinary Shares	Ordinary Shares Series C Non-Voting Convertible Ordinary Shares	Ordinary Shares Series E Non-Voting Convertible Ordinary Shares	Preferred Stock Series C Preferred Shares	Preferred Stock Series D Preferred Stock	Preferred Stock Series E Preferred Stock	Treasury Shares (Series C Preferred shares)	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Currency translation adjustment	Defined benefit pension liability	Unrealized gains (losses) on available-for-sale investments	Retained Earnings	Noncontrolling Interest (excludes Redeemable Noncontrolling Interest)
Balance, beginning of period at Dec. 31, 2017		$ 16,402	$ 2,600	$ 405	$ 389	$ 0	$ 0	$ (421,559)	$ 1,395,067	$ 10,468	$ 11,171		$ 2,440	$ 2,132,912	$ 9,264
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of shares		11							(94)
Amortization of share-based compensation									5,651
Change in other comprehensive income (loss)	$ 909										1,229		(294)
Net earnings (losses) attributable to Enstar Group Limited	(41,210)													(40,428)
Net loss (earnings) attributable to noncontrolling interest	(782)													(782)	(37)
Dividend on preferred shares														0
Change in redemption value of redeemable noncontrolling interests														(369)
Contribution of capital															49
Balance, end of period at Mar. 31, 2018		16,413	2,600	405	389	0	0	(421,559)	1,400,624	11,403	12,400	$ (3,143)	2,146	2,089,760	9,276
Balance, beginning of period at Dec. 31, 2018	3,913,989	17,950	2,600	910	389	400,000	110,000	(421,559)	1,804,664	10,440	10,986		441	1,976,539	12,056
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of shares		8							466
Amortization of share-based compensation									3,977
Change in other comprehensive income (loss)	2,923										(803)		3,642
Net earnings (losses) attributable to Enstar Group Limited	358,751													365,742
Net loss (earnings) attributable to noncontrolling interest	2,148													2,148	396
Dividend on preferred shares														(9,139)
Change in redemption value of redeemable noncontrolling interests														(262)
Contribution of capital															0
Balance, end of period at Mar. 31, 2019	$ 4,280,164	$ 17,958	$ 2,600	$ 910	$ 389	$ 400,000	$ 110,000	$ (421,559)	$ 1,809,107	$ 13,279	$ 10,183	$ (987)	$ 4,083	$ 2,335,028	$ 12,452

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
OPERATING ACTIVITIES:
Net earnings (loss)	$ 365,742	$ (40,428)
Adjustments to reconcile net earnings (loss) to cash flows provided by (used in) operating activities:
Realized losses (gains) on sale of investments	(270)	5,978
Unrealized losses (gains) on investments	(460,521)	137,052
Depreciation and other amortization	7,900	7,576
Earnings from equity method investments	(8,772)	(14,697)
Sales and maturities of trading securities	1,486,423	904,977
Purchases of trading securities	(1,379,411)	(1,733,720)
Other non-cash items	4,687	6,363
Changes in:
Reinsurance balances recoverable	(256,706)	(347,798)
Funds held by reinsured companies	(598,471)	(639,394)
Losses and loss adjustment expenses	685,834	1,587,609
Policy benefits for life and annuity contracts	(2,304)	(2,980)
Insurance and reinsurance balances payable	67,653	119,830
Unearned premiums	108,424	128,973
Premiums receivable	67,489	0
Other operating assets and liabilities	19,441	(193,555)
Net cash flows provided by (used in) operating activities	107,138	(74,214)
INVESTING ACTIVITIES:
Sales and maturities of available-for-sale securities	5,839	22,700
Purchase of available-for-sale securities	(147)	(5,039)
Purchase of other investments	(225,961)	(275,862)
Proceeds from other investments	58,980	32,276
Purchase of equity method investments	(9,762)	0
Other investing activities	(1,956)	(4,304)
Net cash flows used in investing activities	(173,007)	(230,229)
FINANCING ACTIVITIES:
Dividends on preferred shares	(9,139)	0
Contribution by noncontrolling interest	0	49
Receipt of loans	344,000	345,400
Repayment of loans	(102,000)	(132,938)
Net cash flows provided by financing activities	232,861	212,511
EFFECT OF EXCHANGE RATE CHANGES ON FOREIGN CURRENCY CASH AND CASH EQUIVALENTS	(3,925)	15,059
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	163,067	(76,873)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	982,584	1,212,836
CASH AND CASH EQUIVALENTS, END OF PERIOD	1,145,651	1,135,963
Supplemental Cash Flow Information:
Income taxes paid, net of refunds	9	2,461
Interest paid	14,215	10,530
Reconciliation to Consolidated Balance Sheets:
Cash, cash equivalents and restricted cash	$ 982,584	$ 1,212,836

Significant Accounting Policies

3 Months Ended

Mar. 31, 2019

Accounting Policies [Abstract]

SIGNIFICANT ACCOUNTING POLICIES

1. SIGNIFICANT ACCOUNTING POLICIES

Basis of Preparation

These unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("U.S. GAAP") for interim financial information. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, these financial statements reflect all adjustments consisting of normal recurring items considered necessary for a fair presentation under U.S. GAAP. The results of operations for any interim period are not necessarily indicative of results of the full year. These financial statements should be read in conjunction with the consolidated financial statements and related notes included in our Annual Report on Form 10-K for the year ended December 31, 2018. All significant inter-company transactions and balances have been eliminated. In these notes, the terms "we," "us," "our," or "the Company" refer to Enstar Group Limited and its consolidated subsidiaries. Certain prior period amounts have been reclassified to conform to the current period presentation. These reclassifications had no impact on net earnings.

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. Results of changes in estimates are reflected in earnings in the period in which the change is made. Accounting policies that we believe are most dependent on assumptions and estimates are considered to be our critical accounting policies and are related to the determination of:


•	liability for losses and loss adjustment expenses ("LAE");


•	liability for policy benefits for life contracts;


•	reinsurance balances recoverable on paid and unpaid losses;


•	Valuation allowances on reinsurance balances recoverable and deferred tax assets;


•	impairment charges, including other-than-temporary impairments on investment securities classified as available-for-sale, and impairments on goodwill, intangible assets and deferred charge asset;


•	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.New Accounting Standards Adopted in 2019

Accounting Standards Update ("ASU") 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income

In February 2018, the Financial Accounting Standards Board (the "FASB") issued ASU 2018-02, which gives entities the option to reclassify to retained earnings tax effects related to items in accumulated other comprehensive income (“AOCI”) that are deemed stranded in AOCI as a result of the Tax Cuts and Jobs Act (the "Tax Act") enacted in the United States at the end of 2017. The amendments in this guidance eliminate the stranded tax effects resulting from the Tax Act and will improve the usefulness of information reported to financial statement users. We adopted the new standard on January 1, 2019, and that adoption did not have a material impact on our consolidated financial statements and related disclosures.

ASUs 2016-02, 2018-10, 2018-11 and 2019-01, Leases

In February 2016, the FASB issued ASU 2016-02, which is codified in Accounting Standards Codification ("ASC") 842 - Leases, amending the guidance on the classification, measurement and disclosure of leases for both lessors and lessees. The ASU requires lessees to recognize a right-of-use asset and an offsetting lease liability on the balance sheet and to disclose qualitative and quantitative information about leasing arrangements. Subsequently, in July 2018, the FASB issued ASU 2018-10, which clarifies how to apply certain aspects of ASC 842. The amendments in the ASU address a number of issues in the new leases guidance, including (1) the rate implicit in the lease, (2) impairment of the net investment in the lease, (3) lessee reassessment of lease classification, (4) lessor reassessment of lease term and purchase options, (5) variable payments that depend on an index or rate, and (6) certain transition adjustments.

In July 2018, the FASB also issued ASU 2018-11, which adds a transition option for all entities and a practical expedient only for lessors to ASU 2016-02. The transition option, which we elected on adoption of the guidance, allows entities to choose not to apply the new leases standard in the comparative periods they present in their financial statements in the year of adoption. Under the transition option, entities can instead opt to continue to apply the legacy guidance in ASC 840 - Leases, including its disclosure requirements, in the comparative periods presented in the year they adopt the new leases standard. This means that entities that elect this option will only provide annual disclosures for the comparative periods because ASC 840 does not require interim disclosures. Entities that elect this transition option are still required to adopt the new leases standard using the modified retrospective transition method, but they will recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption rather than in the earliest period presented. The practical expedient provides lessors with an option to not separate the non-lease components from the associated lease components when certain criteria are met and requires them to account for the combined component in accordance with the revenue recognition standard in ASC 606 if the associated non-lease components are the predominant components.

In addition, in March 2019, the FASB issued ASU 2019-01 to clarify that in the year of initial adoption of ASC 842, entities are not subject to the transition disclosure requirements in ASC 250-10-50-3 related to the effect of an accounting change on certain interim period financial information. Prior to this clarification, the transition guidance in ASC 842 only excluded the annual disclosures required in ASC 250-10-50-1(b)(2).

We adopted ASU 2016-02 and the related amendments on January 1, 2019 using the modified retrospective transition method as required by the standard and recognized a right-of-use asset and an offsetting lease liability of $51.6 million on our consolidated balance sheet, relating primarily to office space and facilities that we have leased to conduct our business operations. Refer to Note 19 - "Commitments and Contingencies" for further details.Recently Issued Accounting Pronouncements Not Yet Adopted

Note 2 - "Significant Accounting Policies" to the consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2018 describes accounting pronouncements that were not adopted as of December 31, 2018. Those pronouncements have not yet been adopted unless discussed above in "New Accounting Standards Adopted in 2019". In addition, the following relevant accounting pronouncement was issued by the FASB subsequent to the three months ended March 31, 2019 and is yet to be adopted.

ASU 2019-04 - Codification Improvements to ASC 326 - Financial Instruments - Credit Losses, ASC 815 - Derivatives and Hedging and ASC 825 - Financial Instruments

In April 2019, the FASB issued ASU 2019-04, which amends, (1) ASU 2016-13 on credit losses as codified in ASC 326, (2) ASU 2017-12 on hedging activities as codified in ASC 815, and (3) ASU 2016-01 on recognizing and measuring financial instruments as codified in ASC 825-10. The amendments in ASU 2019-04 clarify the scope and also address certain implementation issues related to these three standards. Specifically, the amendments clarify the scope of the credit losses standard and addresses issues related to accrued interest receivable balances, recoveries, variable interest rates and prepayments. With respect to the hedge accounting standard, the amendments address partial-term fair value hedges, fair value hedge basis adjustments and certain transition requirements. On recognizing and measuring financial instruments, the ASU addresses the scope of ASC 825, the requirement for re-measurement under ASC 820 when using the measurement alternative, certain disclosure requirements and which equity securities have to be remeasured at historical exchange rates.

The amendments to the credit losses and hedging standards have the same effective dates and transition requirements as the initial standards, unless an entity has already adopted those standards. For entities that have already adopted the credit losses standard, the amendments are effective for interim and annual reporting periods beginning after December 15, 2019, although early adoption is permitted, and the amendments should be applied on a modified retrospective basis.

For entities that have already adopted ASU 2017-12, which we did during the quarter ended September 30, 2017, the amendments are effective as of the beginning of the next annual period which is January 1, 2020 for us, although early adoption is permitted. The ASU requires entities to either retrospectively apply the amendments as of the date they adopted ASU 2017-12, or prospectively, as of the date they adopt the amendments, with certain exceptions.

The amendments on recognizing and measuring financial instruments are effective for interim and annual reporting periods beginning after December 15, 2019 although early adoption is permitted for entities that have already adopted ASU 2016-01 which we did on January 1, 2018. The ASU requires entities to apply these amendments on a modified retrospective basis, except for those related to equity securities without readily determinable fair values that are measured using the measurement alternative, which entities are required to apply prospectively.

We expect to adopt ASU 2019-04 on January 1, 2020 using the modified retrospective approach required by the standard however, we do not expect that adoption to have a material impact on our consolidated financial statements and related disclosures in view of the composition of our current balance sheet, specifically our financial instruments within the scope of ASU 2016-01 and ASU 2016-13 as well as our existing hedging strategies which largely relate to net investment and cash flow hedging activities.

Significant New Business	3 Months Ended
Significant New Business	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
SIGNIFICANT NEW BUSINESS	2. SIGNIFICANT NEW BUSINESSZurichOn April 16, 2019, we entered into a reinsurance transaction with Zurich Insurance Group ("Zurich"), pursuant to which we will reinsure certain of Zurich's U.S. asbestos and environmental liability insurance portfolios. In the transaction we will assume approximately $0.5 billion of gross reserves, relating to 1986 and prior year business. Completion of the transaction, which is expected to occur in 2019, is subject to, among other things, regulatory approvals and satisfaction of various other customary closing conditions.MaidenOn March 1, 2019, we entered into a Master Agreement with Maiden Holdings, Ltd. ("Maiden Holdings") and Maiden Reinsurance Ltd. (“Maiden Re Bermuda”). Under the Master Agreement, Enstar and Maiden Re Bermuda agreed to enter into an Adverse Development Cover Reinsurance Agreement (“ADC Agreement”) pursuant to which Maiden Re Bermuda will cede and Enstar will reinsure 100% of the liability of Maiden Re Bermuda, as reinsurer, under Maiden Re Bermuda’s two existing quota share agreements with certain insurance companies owned directly or indirectly by AmTrust Financial Services, Inc. (“AmTrust”) for losses incurred on or prior to December 31, 2018 in excess of a $2.44 billion retention, as such figure may be adjusted based upon Maiden Re Bermuda’s final year end reserves for the underlying business, up to a $675 million limit. The premium payable by Maiden Re Bermuda to Enstar under the ADC Agreement will be $500 million. Completion of the transaction is subject to, among other things, regulatory approvals and satisfaction of various closing conditions. The transaction is expected to close in the second quarter of 2019.AmerisureOn February 15, 2019, we entered into a loss portfolio transfer reinsurance agreement with Amerisure Mutual Insurance Company ("Amerisure") and Allianz Risk Transfer (Bermuda) Limited (“ART Bermuda”). In the transaction, Amerisure has agreed to cede, and each of Enstar and ART Bermuda has agreed to severally assume, a 50% quota share of the construction defect losses incurred by Amerisure and certain of its subsidiaries on or before December 31, 2012. At closing, Amerisure paid Enstar and ART Bermuda an aggregate premium of $125.0 million, which was adjusted for a broker commission and paid claims and recoveries from April 1, 2018, and Enstar's subsidiary assumed $60.0 million of net reserves in the transaction. This transaction closed in the second quarter.AmTrust RITC TransactionsOn February 14, 2019, we completed four RITC transactions with Syndicates 1206, 1861, 2526 and 5820 (collectively the "AmTrust RITC Transactions"), managed by AmTrust Syndicates Limited, under which we reinsured to close the 2016 and prior underwriting years. We assumed, among other items, gross loss reserves of £703.8 million ($897.1 million) and net loss reserves of £486.8 million ($620.4 million) relating to the portfolios in exchange for consideration of £539.9 million ($688.2 million) and recorded a deferred charge asset of $20.6 million. We have an investment in AmTrust, as described further in Note 18 - "Related Party Transactions".

Investments

3 Months Ended

Mar. 31, 2019

Investments, Debt and Equity Securities [Abstract]

INVESTMENTS

3. INVESTMENTS We hold: (i) trading portfolios of fixed maturity investments, short-term investments and equities, carried at fair value; (ii) available-for-sale portfolios of fixed maturity investments, carried at fair value; (iii) other investments, carried at fair value; (iv) equity method investments; and (v) funds held - directly managed.Fixed Maturity Investments

Asset Types

The fair values of the underlying asset types of our short-term investments and fixed maturity investments, classified as trading and available-for-sale, and the fixed maturity investments included within our funds held - directly managed balance were as follows:



	March 31, 2019
	Short-term investments, trading		Fixed maturities, trading		Fixed maturities, available-for-sale		Fixed maturities, funds held - directly managed		Total
U.S. government and agency	$	23,188	$	318,695	$	574	$	74,849	$	417,306
U.K. government	1,238		277,205		—		—		278,443
Other government	5,402		673,155		72,099		19,320		769,976
Corporate	43,662		4,343,019		71,846		645,488		5,104,015
Municipal	—		101,747		2,047		56,272		160,066
Residential mortgage-backed	—		342,891		9		86,105		429,005
Commercial mortgage-backed	—		645,751		—		238,373		884,124
Asset-backed	2,570		614,591		—		79,207		696,368
Total fixed maturity and short-term investments	$	76,060	$	7,317,054	$	146,575	$	1,199,614	$	8,739,303



	December 31, 2018
	Short-term investments, trading		Fixed maturities, trading		Fixed maturities, available-for-sale		Fixed maturities, funds held - directly managed		Total
U.S. government and agency	$	45,885	$	389,735	$	573	$	74,052	$	510,245
U.K. government	2,275		298,356		—		—		300,631
Other government	19,064		679,525		73,185		22,036		793,810
Corporate	44,900		4,081,793		75,359		637,788		4,839,840
Municipal	—		73,856		2,480		53,929		130,265
Residential mortgage-backed	—		682,962		12		90,583		773,557
Commercial mortgage-backed	—		488,598		—		224,465		713,063
Asset-backed	1,992		553,968		—		80,521		636,481
Total fixed maturity and short-term investments	$	114,116	$	7,248,793	$	151,609	$	1,183,374	$	8,697,892

Included within residential and commercial mortgage-backed securities as of March 31, 2019 were securities issued by U.S. governmental agencies with a fair value of $294.5 million (as of December 31, 2018: $656.6 million). Included within corporate securities as of March 31, 2019 were senior secured loans of $29.1 million (as of December 31, 2018: $20.4 million).Contractual Maturities

The contractual maturities of our short-term investments and fixed maturity investments, classified as trading and available-for-sale, and the fixed maturity investments included within our funds held - directly managed balance are shown below. Actual maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties.



As of March 31, 2019	Amortized Cost		Fair Value		% of Total Fair Value
One year or less	$	408,671	$	401,606	4.6	%
More than one year through two years	477,168		473,004		5.4	%
More than two years through five years	1,958,078		1,955,798		22.4	%
More than five years through ten years	2,115,535		2,137,694		24.5	%
More than ten years	1,723,351		1,761,704		20.1	%
Residential mortgage-backed	424,195		429,005		4.9	%
Commercial mortgage-backed	884,640		884,124		10.1	%
Asset-backed	698,724		696,368		8.0	%
	$	8,690,362	$	8,739,303	100.0	%

Credit Ratings

The following table sets forth the credit ratings of our short-term investments and fixed maturity investments, classified as trading and available-for-sale, and the fixed maturity investments included within our funds held - directly managed balance as of March 31, 2019:



	Amortized Cost		Fair Value		% of Total		AAA Rated			AA Rated			A Rated			BBB Rated			Non- Investment Grade			Not Rated

U.S. government and agency	$	415,689	$	417,306	4.8	%	$	417,243		$	63		$	—		$	—		$	—		$	—
U.K. government	261,213		278,443		3.2	%	644			277,799			—			—			—			—
Other government	769,300		769,976		8.8	%	308,413			198,228			55,991			171,579			35,765			—
Corporate	5,079,783		5,104,015		58.4	%	132,282			506,434			2,517,323			1,737,171			197,543			13,262
Municipal	156,818		160,066		1.8	%	12,284			81,059			49,814			16,909			—			—
Residential mortgage-backed	424,195		429,005		4.9	%	309,100			55,819			2,054			3,119			51,372			7,541
Commercial mortgage-backed	884,640		884,124		10.1	%	641,337			87,319			77,117			61,139			6,514			10,698
Asset-backed	698,724		696,368		8.0	%	302,491			99,371			164,249			110,806			18,111			1,340
Total	$	8,690,362	$	8,739,303	100.0	%	$	2,123,794		$	1,306,092		$	2,866,548		$	2,100,723		$	309,305		$	32,841
% of total fair value							24.3		%	14.9		%	32.9		%	24.0		%	3.5		%	0.4		%

Unrealized Gains and Losses Available-for-sale Fixed Maturity Investments

The amortized cost and fair values of our fixed maturity investments classified as available-for-sale were as follows:



As of March 31, 2019	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses (Non-OTTI)			Fair Value
U.S. government and agency	$	574	$	—	$	—		$	574
Other government	69,918		2,730		(549		)	72,099
Corporate	70,120		2,230		(504		)	71,846
Municipal	2,054		4		(11		)	2,047
Residential mortgage-backed	9		—		—			9
	$	142,675	$	4,964	$	(1,064	)	$	146,575



As of December 31, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses (Non-OTTI)			Fair Value
U.S. government and agency	$	576	$	—	$	(3	)	$	573
Other government	72,811		1,219		(845		)	73,185
Corporate	75,535		1,006		(1,182		)	75,359
Municipal	2,499		—		(19		)	2,480
Residential mortgage-backed	12		—		—			12
	$	151,433	$	2,225	$	(2,049	)	$	151,609

Gross Unrealized Losses on Available-for-sale Fixed Maturity Investments

The following tables summarize our fixed maturity investments classified as available-for-sale that are in a gross unrealized loss position:



	12 Months or Greater					Less Than 12 Months					Total
As of March 31, 2019	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Fixed maturity investments, at fair value
Other government	3,570		(318		)	6,260		(231		)	9,830		(549		)
Corporate	12,351		(405		)	4,208		(99		)	16,559		(504		)
Municipal	1,683		(11		)	—		—			1,683		(11		)
Total fixed maturity investments	$	17,604	$	(734	)	$	10,468	$	(330	)	$	28,072	$	(1,064	)



	12 Months or Greater					Less Than 12 Months					Total
As of December 31, 2018	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Fixed maturity investments, at fair value
U.S. government and agency	$	573	$	(3	)	$	—	$	—		$	573	$	(3	)
Other government	7,351		(345		)	11,000		(500		)	18,351		(845		)
Corporate	11,888		(629		)	25,227		(553		)	37,115		(1,182		)
Municipal	1,783		(18		)	283		(1		)	2,066		(19		)
Residential mortgage-backed	12		—			—		—			12		—
Total fixed maturity investments	$	21,607	$	(995	)	$	36,510	$	(1,054	)	$	58,117	$	(2,049	)

As of March 31, 2019 and December 31, 2018, the number of securities classified as available-for-sale in an unrealized loss position was 55 and 88, respectively. Of these securities, the number of securities that had been in an unrealized loss position for twelve months or longer was 43 and 42, respectively.Other-Than-Temporary Impairment on Available-for-sale Fixed Maturity InvestmentsFor the three months ended March 31, 2019 and 2018, we did not recognize any other-than-temporary impairment losses on our available-for-sale securities. We determined that no credit losses existed as of March 31, 2019 or December 31, 2018. A description of our other-than-temporary impairment process is included in Note 2 - "Significant Accounting Policies" in the notes to our consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2018. There were no changes to our process during the three months ended March 31, 2019.Equity Investments

The following table summarizes our equity investments:



	March 31, 2019		December 31, 2018
Publicly traded equity investments in common and preferred stocks	$	171,710	$	138,415
Privately held equity investments in common and preferred stocks	228,710		228,710
	$	400,420	$	367,125

Our publicly traded equity investments in common and preferred stocks predominantly trade on major exchanges and are managed by our external advisors. Our publicly traded equity investments are widely diversified, and there is no significant concentration in any specific industry.

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. Included within the above balance as of March 31, 2019 and December 31, 2018 is an indirect investment in AmTrust, with a fair value of $200.0 million and $200.0 million, respectively. Refer to Note 18 - "Related Party Transactions" for further information.Other Investments, at fair value

The following table summarizes our other investments carried at fair value:



	March 31, 2019		December 31, 2018
Hedge funds	$	979,270	$	852,584
Fixed income funds	587,093		403,858
Equity funds	374,249		333,681
Private equity funds	235,538		248,628
CLO equities	41,434		39,052
CLO equity fund	40,348		37,260
Private credit funds	53,258		33,381
Other	13,155		9,313
	$	2,324,345	$	1,957,757

The valuation of our other investments is described in Note 8 - "Fair Value Measurements". Due to a lag in the valuations of certain funds reported by the managers, we may record changes in valuation with up to a three-month lag. We regularly review and discuss fund performance with the fund managers to corroborate the reasonableness of the reported net asset values and to assess whether any events have occurred within the lag period that would affect the valuation of the investments. The following is a description of the nature of each of these investment categories:

•

Hedge funds may invest in a wide range of instruments, including debt and equity securities, and utilize various sophisticated strategies to achieve their objectives. We invest in a mixture of fixed income, equity and multi-strategy hedge funds. The hedge funds in which we invest have various imposed lock-up periods of up to three years and redemption terms, predominantly 60 and 90 days. Certain of the hedge funds in which we invest that are past their lock up periods are currently eligible for redemption, while others, with a market value of $891.6 million, are still in the lock-up period. Investments of $72.4 million in fixed income hedge funds were subject to gates or side-pockets, where redemptions are subject to the sale of underlying investments. A gate is the ability to deny or delay a redemption request, whereas a side-pocket is a designated account for which the investor loses its redemption rights.

•

Fixed income funds comprise a number of positions in diversified fixed income funds that are managed by third-party managers. Underlying investments vary from high-grade corporate bonds to non-investment grade senior secured loans and bonds, but are generally invested in liquid fixed income markets. These funds have regularly published prices. One of the funds in which we invest, with a market value of $43.7 million, has a lock-up period of up to two years and is eligible for quarterly redemptions thereafter with 65 days' notice. Another fund, with a market value of $73.7 million, is not currently eligible for redemption. All other funds have liquidity terms that vary from daily up to 30 days' notice.


•	Equity funds invest in a diversified portfolio of U.S. and international publicly-traded equity securities. The funds have liquidity terms that vary from daily up to quarterly.


•	Private equity funds invest primarily in the financial services industry. All of our investments in private equity funds are subject to restrictions on redemptions and sales that are determined by the governing documents and limit our ability to liquidate those investments. These restrictions have been in place since the dates of our initial investments.


•	CLO equities comprise investments in the equity tranches of term-financed securitizations of diversified pools of corporate bank loans.


•	CLO equity fund invests primarily in the equity tranches of term-financed securitizations of diversified pools of corporate bank loans. This fund has a fair value of $40.3 million and approximately 28% of the fund is eligible for redemption.


•	Private credit funds invest in direct senior or collateralized loans. The investments are subject to restrictions on redemption and sales that are determined by the governing documents and limit our ability to liquidate our positions in the funds.


•	Others comprise of various investments including real estate debt funds that invest primarily in European real estate, call options on equities and a fund that provides loans to educational institutions throughout the United States and its territories.

The increase in our other investments carried at fair value between March 31, 2019 and December 31, 2018 was primarily attributable to unrealized gains of $204.7 million and net additional subscriptions of $167.0 million to hedge funds, equity funds and fixed income funds.

As of March 31, 2019, we had unfunded commitments of $210.8 million to private equity funds.Equity Method Investments

The following table summarizes our equity method investments:



	March 31, 2019						December 31, 2018
	Investment		Ownership %		Carrying Value		Investment		Ownership %		Carrying Value
Enhanzed Re	$	94,800	47.4	%	$	91,883	$	94,800	47.4	%	$	94,800
Citco	50,000		31.9	%	50,917		50,000		31.9	%	50,812
Monument	26,600		26.6	%	47,746		26,600		26.6	%	42,193
Clear Spring	11,210		20.0	%	$	10,070	11,210		20.0	%	10,070
Other	25,012		~30%		20,407		15,250		~30%		6,632
	$	207,622			$	221,023	$	197,860			$	204,507

Refer to Note 18 - "Related Party Transactions" for further information regarding our investments in Enhanzed Re, Citco, Monument and Clear Spring.

As of March 31, 2019, we had unfunded commitments of $152.3 million related to equity method investments.Funds Held

Under funds held arrangements, the reinsured company has retained funds that would otherwise have been remitted to our reinsurance subsidiaries. We either have (i) funds held by reinsured companies, which are carried at amortized cost and on which we receive a fixed crediting rate, or (ii) funds held - directly managed, which are carried at fair value and on which we receive the underlying return on the portfolio. The investment returns on both categories of funds held are recognized in net investment income and net realized and unrealized gains (losses). The funds held balance is credited with investment income and losses payable are deducted.

Funds Held - Directly Managed

Funds held - directly managed, where we receive the underlying return on the investment portfolio, are carried at fair value, either because we elected the fair value option at the inception of the reinsurance contract, or because it represents the aggregate of funds held at amortized cost and the fair value of an embedded derivative. The embedded derivative relates to our contractual right to receive the return on the underlying investment portfolio supporting the reinsurance contract. We include the estimated fair value of these embedded derivatives in the consolidated balance sheets with the host contract in order to reflect the expected settlement of these features with the host contract. The change in the fair value of the embedded derivative is included in net unrealized gains (losses). The following table summarizes the components of the funds held - directly managed as of March 31, 2019 and December 31, 2018:



	2019		2018
Fixed maturity investments, trading	$	1,199,614	$	1,183,374
Other assets	88,596		14,780
	$	1,288,210	$	1,198,154

The following table summarizes the fixed maturity investment components of funds held - directly managed as of March 31, 2019 and December 31, 2018:



	March 31, 2019								December 31, 2018
	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
Fixed maturity investments, at amortized cost	$	181,689	$	1,019,636		$	1,201,325		$	179,670		$	1,044,377		$	1,224,047
Net unrealized gains (losses):
Change in fair value - fair value option accounting	978		—			978			(2,733		)	—			(2,733		)
Change in fair value - embedded derivative accounting	—		(2,689		)	(2,689		)	—			(37,940		)	(37,940		)
Fixed maturity investments within funds held - directly managed, at fair value	$	182,667	$	1,016,947		$	1,199,614		$	176,937		$	1,006,437		$	1,183,374

Refer to the sections above for details of the fixed maturity investments within our funds held - directly managed portfolios.

Funds Held by Reinsured Companies

Funds held by reinsured companies, where we received a fixed crediting rate, are carried at cost on our consolidated balance sheets. As of March 31, 2019 and December 31, 2018, we had funds held by reinsured companies of $919.7 million and $321.3 million, respectively. In connection with the AmTrust RITC transactions, we have recorded in aggregate $601.9 million as funds held, which is expected to be received in the second quarter of 2019 and subsequently invested in accordance with our investment guidelines.Net Investment Income

Major categories of net investment income are summarized as follows:



	Three Months Ended
	March 31,
	2019			2018
Fixed maturity investments	$	58,070		$	43,888
Short-term investments and cash and cash equivalents	3,860			2,082
Funds held	5,798			3,129
Funds held - directly managed	9,750			8,626
Investment income from fixed maturities and cash and cash equivalents	77,478			57,725
Equity investments	3,380			1,490
Other investments	2,114			3,314
Life settlements and other	—			6,659
Investment income from equities and other investments	5,494			11,463
Gross investment income	82,972			69,188
Investment expenses	(4,276		)	(2,869		)
Net investment income	$	78,696		$	66,319

Net Realized and Unrealized Gains and Losses

Components of net realized and unrealized gains and losses were as follows:



	Three Months Ended
	March 31,
	2019			2018
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, available-for-sale	$	4		$	7
Gross realized losses on fixed maturity securities, available-for-sale	(65		)	(37		)
Net realized losses on fixed maturity securities, trading	(611		)	(6,947		)
Net realized gains (losses) on funds held - directly managed	(1,606		)	96
Net realized gains on equity investments	2,548			903
Total net realized gains (losses) on sale	$	270		$	(5,978	)
Net unrealized gains (losses):
Fixed maturity securities, trading	$	209,467		$	(100,301	)
Fixed maturity securities in funds held - directly managed portfolios	38,962			(30,924		)
Equity investments	7,383			3,835
Other Investments	204,709			(9,662		)
Total net unrealized gains (losses)	460,521			(137,052		)
Net realized and unrealized gains (losses)	$	460,791		$	(143,030	)

The gross realized gains and losses on available-for-sale investments included in the table above resulted from sales of $1.2 million and $7.5 million for the three months ended March 31, 2019 and 2018, respectively.Restricted Assets

We utilize trust accounts to collateralize business with our insurance and reinsurance counterparties. We are also required to maintain investments and cash and cash equivalents on deposit with regulatory authorities and Lloyd's to support our insurance and reinsurance operations. The investments and cash and cash equivalents on deposit are available to settle insurance and reinsurance liabilities. Collateral generally takes the form of assets held in trust, letters of credit or funds held. The assets used as collateral are primarily highly rated fixed maturity securities. The carrying value of our restricted assets, including restricted cash of $427.6 million and $380.5 million, as of March 31, 2019 and December 31, 2018, respectively, was as follows:



	March 31, 2019		December 31, 2018
Collateral in trust for third party agreements	$	4,276,436	$	4,336,752
Assets on deposit with regulatory authorities	583,780		579,048
Collateral for secured letter of credit facilities	124,576		127,841
Funds at Lloyd's ⁽¹⁾	642,068		354,589
	$	5,626,860	$	5,398,230

⁽¹⁾Our businesses include three Lloyd's syndicates. Lloyd's determines the required capital principally through the annual business plan of each syndicate. This capital is referred to as "Funds at Lloyd's" and will be drawn upon in the event that a syndicate has a loss that cannot be funded from other sources. We also utilize unsecured letters of credit for Funds at Lloyd's, as described in Note 12 - "Debt Obligations and Credit Facilities".

The increase in the Funds at Lloyd's was primarily due to the loss portfolio transfer reinsurance transactions as described in Note 2 - "Significant New Business".

Derivative and Hedging Instruments

3 Months Ended

Mar. 31, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

DERIVATIVE AND HEDGING INSTRUMENTS

4. DERIVATIVES AND HEDGING INSTRUMENTSForeign Currency Hedging of Net Investments in Foreign Operations

We use foreign currency forward contracts in qualifying hedging relationships to hedge the foreign currency exchange rate risk associated with certain of our net investments in foreign operations. As of March 31, 2019 and December 31, 2018, we had forward currency contracts in place, which we had designated as hedges of our net investments in foreign operations.

The following table presents the gross notional amounts and estimated fair values recorded within other assets and other liabilities related to our qualifying foreign currency forward exchange rate contracts as of March 31, 2019 and December 31, 2018.



	March 31, 2019						December 31, 2018
			Fair Value						Fair Value
	Gross Notional Amount		Assets		Liabilities		Gross Notional Amount		Assets		Liabilities
Foreign currency forward - AUD	$	41,874	$	22	$	25	$	42,258	$	1,377	$	—
Foreign currency forward - EUR	115,575		1,568		—		66,422		238		300
Total qualifying hedges	$	157,449	$	1,590	$	25	$	108,680	$	1,615	$	300

The following table presents the amounts of the net gains and losses deferred in the cumulative translation adjustment ("CTA") account, which is a component of accumulated other comprehensive income (loss) ("AOCI"), in shareholders' equity, relating to our foreign currency forward exchange rate contracts for the three months ended March 31, 2019 and 2018.



	Amount of Gains (Losses) Deferred in AOCI
	Three Months Ended
	March 31,
	2019			2018
Foreign currency forward - AUD	$	(327	)	$	530
Foreign currency forward - EUR	1,855			—
Net gains on qualifying derivative hedges	$	1,528		$	530

Non-derivative Hedging Instruments of Net Investments in Foreign Operations

As of March 31, 2018 there were borrowings of €60.0 million ($73.7 million) under our revolving credit facility that were designated as non-derivative hedges of our net investment in certain subsidiaries whose functional currency is denominated in Euros. These Euro-denominated borrowings were repaid in full and replaced by a Euro-denominated foreign currency forward contract in a qualifying hedging arrangement during the year ended December 31, 2018. The net losses deferred in the CTA account in AOCI relating to these qualifying Euro-loan derivative hedging instruments for the three months ended March 31, 2018 was $1.2 million.Derivatives Not Designated or Not Qualifying as Hedging InstrumentsFrom time to time, we may also utilize foreign currency forward contracts as part of our overall foreign currency risk management strategy or to obtain exposure to a particular financial market, as well as for yield enhancement in non-qualifying hedging relationships. We may also utilize equity call option instruments either to obtain exposure to a particular equity instrument or for yield enhancement in non-qualifying hedging relationships.Foreign Currency Forward Contracts

The following table presents the gross notional amounts and estimated fair values recorded within other assets and other liabilities related to our non-qualifying foreign currency forward hedging relationships as of March 31, 2019 and December 31, 2018.



	March 31, 2019						December 31, 2018
			Fair Value						Fair Value
	Gross Notional Amount		Assets		Liabilities		Gross Notional Amount		Assets		Liabilities
Foreign currency forward - AUD	$	73,953	$	71	$	25	$	45,427	$	1,952	$	310
Foreign currency forward - CAD	122,690		1,750		—		55,050		1,441		—
Foreign currency forward - EUR	28,389		419		14		54,282		139		301
Foreign currency forward - GBP	224,951		1,448		—		256,959		1,554		72
Total non-qualifying hedges	$	449,983	$	3,688	$	39	$	411,718	$	5,086	$	683

The following table presents the amounts of the net gains (losses) included in earnings related to our non-qualifying foreign currency forward contracts during the three months ended March 31, 2019 and 2018.



	Gains (Losses) on non-qualifying-hedges included in net earnings
	Three Months Ended March 31,
	2019			2018
Foreign currency forward - AUD	$	(765	)	$	982
Foreign currency forward - CAD	1			2,040
Foreign currency forward - EUR	1,205			(267		)
Foreign currency forward - GBP	(4,059		)	(6,842		)
Net losses on non-qualifying hedges	$	(3,618	)	$	(4,087	)

Investments in Call Options on EquitiesDuring the three months ended March 31, 2019 and 2018 we recorded unrealized losses in net earnings of $0.2 million and $2.5 million respectively, on the call options on equities that we purchased in 2018 at a cost of $10.0 million. These call options on equities had a fair value of $0.2 million and $0.4 million as of March 31, 2019 and December 31, 2018, respectively.

Reinsurance Balances Recoverable on Paid and Unpaid Losses

3 Months Ended

Mar. 31, 2019

Insurance [Abstract]

REINSURANCE BALANCES RECOVERABLE ON PAID AND UNPAID LOSSES

5. REINSURANCE BALANCES RECOVERABLE ON PAID AND UNPAID LOSSESThe following tables provide the total reinsurance balances recoverable:



	March 31, 2019
	Non-life Run-off			Atrium		StarStone			Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	1,007,758		$	11,242	$	290,095		$	1,309,095
IBNR	695,921			19,726		178,143			893,790
Fair value adjustments	(14,364		)	714		(1,643		)	(15,293		)
Fair value adjustments - fair value option	(109,669		)	—		—			(109,669		)
Total reinsurance reserves recoverable	1,579,646			31,682		466,595			2,077,923
Paid losses recoverable	170,633			647		37,244			208,524
	$	1,750,279		$	32,329	$	503,839		$	2,286,447
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	1,015,022		$	32,329	$	503,839		$	1,551,190
Reinsurance balances recoverable - fair value option	735,257			—		—			735,257
Total	$	1,750,279		$	32,329	$	503,839		$	2,286,447



	December 31, 2018
	Non-life Run-off			Atrium			StarStone			Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	901,772		$	18,891		$	263,065		$	1,183,728
IBNR	609,434			19,247			201,784			830,465
Fair value adjustments	(14,344		)	630			(1,899		)	(15,613		)
Fair value adjustments - fair value option	(130,739		)	—			—			(130,739		)
Total reinsurance reserves recoverable	1,366,123			38,768			462,950			1,867,841
Paid losses recoverable	138,265			(256		)	23,813			161,822
	$	1,504,388		$	38,512		$	486,763		$	2,029,663
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	764,797		$	38,512		$	486,763		$	1,290,072
Reinsurance balances recoverable - fair value option	739,591			—			—			739,591
Total	$	1,504,388		$	38,512		$	486,763		$	2,029,663

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

The fair value adjustments, determined on acquisition of insurance and reinsurance 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 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 8 - "Fair Value Measurements".

As of March 31, 2019 and December 31, 2018, we had reinsurance balances recoverable of $2,286.4 million and $2,029.7 million, respectively. The increase of $256.8 million in reinsurance balances recoverable was primarily related to the AmTrust RITC transactions, which closed during the first quarter of 2019.Top Ten Reinsurers



	March 31, 2019
	Non-life Run-off		Atrium		StarStone		Total		% of Total
Top ten reinsurers	$	1,202,892	$	22,421	$	299,058	$	1,524,371	66.7	%
Other reinsurers > $1 million	532,030		8,149		201,709		741,888		32.4	%
Other reinsurers < $1 million	15,357		1,759		3,072		20,188		0.9	%
Total	$	1,750,279	$	32,329	$	503,839	$	2,286,447	100.0	%



	December 31, 2018
	Non-life Run-off		Atrium		StarStone		Total		% of Total
Top ten reinsurers	$	1,124,079	$	25,239	$	263,192	$	1,412,510	69.6	%
Other reinsurers > $1 million	364,098		12,091		220,123		596,312		29.4	%
Other reinsurers < $1 million	16,211		1,182		3,448		20,841		1.0	%
Total	$	1,504,388	$	38,512	$	486,763	$	2,029,663	100.0	%



	March 31, 2019		December 31, 2018
Information regarding top ten reinsurers:
Number of top 10 reinsurers rated A- or better	8		7
Number of top 10 non-rated reinsurers ⁽¹⁾	2		3

Top 10 rated A- or better reinsurers recoverables	$	1,285,067	$	1,096,272
Top 10 collaterized non-rated reinsurers recoverables ⁽¹⁾	239,304		316,238
	$	1,524,371	$	1,412,510

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

Hannover Ruck SE ⁽²⁾	$	297,129	$	279,723
Lloyd's Syndicates ⁽³⁾	$	392,205	$	334,509

⁽¹⁾For the two non-rated reinsurers as of March 31, 2019 and three non-rated reinsurers as of December 31, 2018, we hold security in the form of pledged assets in trust or letters of credit issued to us in the full amount of the recoverable.

⁽²⁾ Hannover Ruck SE is rated AA- by Standard & Poor’s and A+ by A.M. Best.

⁽³⁾ Lloyd's Syndicates are rated A+ by Standard & Poor's and A by A.M. Best. Provisions for Uncollectible Reinsurance Balances Recoverable

We evaluate and monitor concentration of credit risk among our reinsurers, and provisions are made for amounts considered potentially uncollectible.

The following table shows our reinsurance balances recoverable by rating of reinsurer and our provisions for uncollectible reinsurance balances recoverable ("provisions for bad debt"). The majority of the provisions for bad debt relate to the Non-life Run-off segment.



	March 31, 2019								December 31, 2018
	Gross		Provisions for Bad Debt		Net		Provisions as a % of Gross		Gross		Provisions for Bad Debt		Net		Provisions as a % of Gross
Reinsurers rated A- or above	$	1,883,418	$	54,048	$	1,829,370	2.9	%	$	1,612,464	$	51,519	$	1,560,945	3.2	%
Reinsurers rated below A-, secured	421,205		—		421,205		—	%	430,852		—		430,852		—	%
Reinsurers rated below A-, unsecured	143,303		107,431		35,872		75.0	%	143,079		105,213		37,866		73.5	%
Total	$	2,447,926	$	161,479	$	2,286,447	6.6	%	$	2,186,395	$	156,732	$	2,029,663	7.2	%

10. PREMIUMS WRITTEN AND EARNED

The following table provides a summary of premiums written and earned in our Non-life Run-off, Atrium and StarStone segments and Other activities:



	Three Months Ended March 31,
	2019						2018
	Premiums Written			Premiums Earned			Premiums Written			Premiums Earned
Non-life Run-off
Gross	$	(20,877	)	$	83,966		$	7,380		$	13,110
Ceded	1,699			(7,292		)	(7,280		)	(5,932		)
Net	$	(19,178	)	$	76,674		$	100		$	7,178
Atrium
Gross	$	53,985		$	43,386		$	49,442		$	39,674
Ceded	(7,486		)	(4,633		)	(7,948		)	(4,451		)
Net	$	46,499		$	38,753		$	41,494		$	35,223
StarStone
Gross	$	251,373		$	268,264		$	304,989		$	234,943
Ceded	(56,772		)	(55,002		)	(124,426		)	(108,117		)
Net	$	194,601		$	213,262		$	180,563		$	126,826
Other
Gross	$	864		$	6,673		$	1,037		$	1,050
Ceded	(19		)	(75		)	(47		)	(58		)
Net	$	845		$	6,598		$	990		$	992
Total
Gross	$	285,345		$	402,289		$	362,848		$	288,777
Ceded	(62,578		)	(67,002		)	(139,701		)	(118,558		)
Total	$	222,767		$	335,287		$	223,147		$	170,219

Gross premiums written for the three months ended March 31, 2019 and 2018 were $285.3 million and $362.8 million, respectively, a decrease of $77.5 million. The decrease was primarily due to a decrease in gross written premiums in our StarStone segment due to our strategy to exit certain lines of business, and reductions in gross written premiums in our Non-life Run-off segment for which associated unearned premium was also released.

Deferred Charge Assets

3 Months Ended

Mar. 31, 2019

Insurance [Abstract]

DEFERRED CHARGE ASSETS

6. DEFERRED CHARGE ASSETS

Deferred charge assets 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 insurance and reinsurance 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. Deferred charge assets are included in other assets on our consolidated balance sheets. The following table presents a reconciliation of the deferred charge assets:



	Three Months Ended March 31,
	2019			2018
Beginning carrying value	$	86,585		$	80,192
Recorded during the period	20,632			—
Amortization	(7,063		)	(5,081		)
Ending carrying value	$	100,154		$	75,111

Deferred charge assets 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. Deferred charge assets amortization is adjusted at each reporting period to reflect new estimates of the amount and timing of remaining loss 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 the amount of periodic amortization. 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 three months ended March 31, 2019 we completed our assessment for impairment of deferred charge assets and concluded that there had been no impairment of our carried deferred charge assets amount.

Further information on deferred charge assets recorded during the three months ended March 31, 2019, is included in Note 2 - "Significant New Business".

Losses and Loss Adjustment Expenses

3 Months Ended

Mar. 31, 2019

Insurance [Abstract]

LOSSES AND LOSS ADJUSTMENT EXPENSES

7. 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 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, which include workers' compensation, general casualty, asbestos and environmental, marine, aviation and transit, construction defects, property, motor and other non-life lines of business. Refer to Note 10 - "Losses and Loss Adjustment Expenses" to the consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2018 for more information on establishing the liability for losses and LAE.The following table summarizes the liability for losses and LAE by segment:



	March 31, 2019
	Non-life Run-off			Atrium		StarStone			Other		Total
Outstanding losses	$	4,624,209		$	86,986	$	824,366		$	6,647	$	5,542,208
IBNR	3,694,932			135,411		840,306			14,335		4,684,984
Fair value adjustments	(209,631		)	4,691		(404		)	—		(205,344		)
Fair value adjustments - fair value option	(300,774		)	—		—			—		(300,774		)
ULAE	346,238			2,292		26,418			—		374,948
Total	$	8,154,974		$	229,380	$	1,690,686		$	20,982	$	10,096,022

Reconciliation to Consolidated Balance Sheet:
Loss and loss adjustment expenses	$	5,307,181		$	229,380	$	1,690,686		$	20,982	$	7,248,229
Loss and loss adjustment expenses, at fair value	2,847,793			—		—			—		2,847,793
Total	$	8,154,974		$	229,380	$	1,690,686		$	20,982	$	10,096,022



	December 31, 2018
	Non-life Run-off			Atrium		StarStone			Other		Total
Outstanding losses	$	4,271,769		$	94,885	$	796,194		$	6,052	$	5,168,900
IBNR	3,527,767			140,521		787,894			12,809		4,468,991
Fair value adjustments	(217,527		)	3,476		(467		)	—		(214,518		)
Fair value adjustments - fair value option	(374,752		)	—		—			—		(374,752		)
ULAE	333,405			2,402		25,076			—		360,883
Total	$	7,540,662		$	241,284	$	1,608,697		$	18,861	$	9,409,504

Reconciliation to Consolidated Balance Sheet:
Loss and loss adjustment expenses	$	4,666,607		$	241,284	$	1,608,697		$	18,861	$	6,535,449
Loss and loss adjustment expenses, at fair value	2,874,055			—		—			—		2,874,055
Total	$	7,540,662		$	241,284	$	1,608,697		$	18,861	$	9,409,504

The overall increase in the liability for losses and LAE between December 31, 2018 and March 31, 2019 was primarily attributable to the AmTrust RITC Transactions in our Non-life Run-off segment, as described in Note 2 - "Significant New Business".The table below provides a reconciliation of the beginning and ending liability for losses and LAE:



	Three Months Ended
	March 31,
	2019			2018
Balance as of beginning of period	$	9,409,504		$	7,398,088
Less: reinsurance reserves recoverable	1,867,841			1,870,033
Less: deferred charge assets on retroactive reinsurance	86,585			80,192
Net balance as of beginning of period	7,455,078			5,447,863
Net incurred losses and LAE:
Current period	217,266			95,154
Prior periods	95,138			(75,620)
Total net incurred losses and LAE	312,404			19,534
Net paid losses:
Current period	(28,029		)	(8,103)
Prior periods	(461,605		)	(350,646)
Total net paid losses	(489,634		)	(358,749)
Effect of exchange rate movement	19,679			57,727
Assumed business	620,418			1,527,551
Net balance as of March 31	7,917,945			6,693,926
Plus: reinsurance reserves recoverable	2,077,923			2,217,033
Plus: deferred charge assets on retroactive reinsurance	100,154			75,111
Balance as of March 31	$	10,096,022		$	8,986,070

The tables below provide the net incurred losses and LAE by segment:



	Three Months Ended
	March 31, 2019
	Non-life Run-off			Atrium			StarStone			Other		Total
Net losses paid	$	349,069		$	22,313		$	115,417		$	2,835	$	489,634
Net change in case and LAE reserves	(77,701		)	(413		)	2,056			595		(75,463		)
Net change in IBNR reserves	(232,895		)	(5,817		)	76,424			1,526		(160,762		)
Increase in estimates of net ultimate losses	38,473			16,083			193,897			4,956		253,409
Increase (reduction) in provisions for unallocated LAE	(15,175		)	—			1,348			—		(13,827		)
Amortization of deferred charge assets	7,064			—			—			—		7,064
Amortization of fair value adjustments	8,779			1,131			(193		)	—		9,717
Changes in fair value - fair value option	56,041			—			—			—		56,041
Net incurred losses and LAE	$	95,182		$	17,214		$	195,052		$	4,956	$	312,404



	Three Months Ended
	March 31, 2018
	Non-life Run-off			Atrium			StarStone			Total
Net losses paid	$	252,584		$	17,530		$	88,635		$	358,749
Net change in case and LAE reserves	(123,486		)	3,890			(4,475		)	(124,071		)
Net change in IBNR reserves	(154,111		)	(1,709		)	(8,871		)	(164,691		)
Increase (reduction) in estimates of net ultimate losses	(25,013		)	19,711			75,289			69,987
Increase (reduction) in provisions for unallocated LAE	(14,952		)	—			192			(14,760		)
Amortization of deferred charge assets	5,081			—			—			5,081
Amortization of fair value adjustments	2,147			(2,539		)	(141		)	(533		)
Changes in fair value - fair value option	(40,241		)	—			—			(40,241		)
Net incurred losses and LAE	$	(72,978	)	$	17,172		$	75,340		$	19,534

Non-Life Run-off Segment

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



	Three Months Ended
	March 31,
	2019			2018
Balance as of beginning of period	$	7,540,662		$	5,949,472
Less: reinsurance reserves recoverable	1,366,123			1,377,485
Less: deferred charge assets on retroactive insurance	86,585			80,192
Net balance as of beginning of period	6,087,954			4,491,795
Net incurred losses and LAE:
Current period	49,071			346
Prior periods	46,111			(73,324		)
Total net incurred losses and LAE	95,182			(72,978		)
Net paid losses:
Current period	(18,014		)	(1		)
Prior periods	(331,055		)	(252,583		)
Total net paid losses	(349,069		)	(252,584		)
Effect of exchange rate movement	20,689			55,403
Assumed business	620,418			1,517,283
Net balance as of March 31	6,475,174			5,738,919
Plus: reinsurance reserves recoverable	1,579,646			1,703,481
Plus: deferred charge assets on retroactive reinsurance	100,154			75,111
Balance as of March 31	$	8,154,974		$	7,517,511

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



	Three Months Ended March 31,
	2019								2018
	Prior Period			Current Period		Total			Prior Period			Current Period		Total
Net losses paid	$	331,055		$	18,014	$	349,069		$	252,583		$	1	$	252,584
Net change in case and LAE reserves	(97,573		)	19,872		(77,701		)	(123,492		)	6		(123,486		)
Net change in IBNR reserves	(243,815		)	10,920		(232,895		)	(154,450		)	339		(154,111		)
Increase (reduction) in estimates of net ultimate losses	(10,333		)	48,806		38,473			(25,359		)	346		(25,013		)
Increase (reduction) in provisions for unallocated LAE	(15,440		)	265		(15,175		)	(14,952		)	—		(14,952		)
Amortization of deferred charge assets	7,064			—		7,064			5,081			—		5,081
Amortization of fair value adjustments	8,779			—		8,779			2,147			—		2,147
Changes in fair value - fair value option	56,041			—		56,041			(40,241		)	—		(40,241		)
Net incurred losses and LAE	$	46,111		$	49,071	$	95,182		$	(73,324	)	$	346	$	(72,978	)

Net change in case and LAE reserves comprises the movement during the period 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. Net change in IBNR represents the gross change in our actuarial estimates of IBNR, less amounts recoverable.

Three Months Ended March 31, 2019

The increase in net incurred losses and LAE for the three months ended March 31, 2019 of $95.2 million included net incurred losses and LAE of $49.1 million related to current period net earned premium, primarily for the run-off business acquired with the AmTrust RITC Transactions and the acquisition of Maiden Reinsurance North America, Inc. ("Maiden Re North America"). Excluding current period net incurred losses and LAE of $49.1 million, the increase in net incurred losses and LAE liabilities relating to prior periods was $46.1 million, which was attributable to an increase in the fair value of liabilities of $56.0 million related to our assumed retroactive reinsurance agreements for which we have elected the fair value option primarily as a result of a decrease in corporate bond yields, amortization of fair value adjustments over the estimated payout period relating to companies acquired of $8.8 million and the amortization of the deferred charge assets of $7.1 million, partially offset by a reduction in estimates of net ultimate losses of $10.3 million and a reduction in provisions for unallocated LAE of $15.4 million relating to 2019 run-off activity. The reduction in estimates of net ultimate losses of $10.3 million for the three months ended March 31, 2019 included a net reduction in case and IBNR reserves of $341.4 million, partially offset by net losses paid of $331.1 million.

Three Months Ended March 31, 2018

The reduction in net incurred losses and LAE for the three months ended March 31, 2018 of $73.0 million included net incurred losses and LAE of $0.3 million related to current period net earned premium. Excluding current period net incurred losses and LAE of $0.3 million, the reduction in net incurred losses and LAE liabilities relating to prior periods was $73.3 million, which was attributable to a reduction in estimates of net ultimate losses of $25.4 million, a reduction in provisions for unallocated LAE of $15.0 million, relating to 2018 run-off activity, and a reduction in the fair value of liabilities of $40.2 million related to our assumed retroactive reinsurance agreements for which we have elected the fair value option, partially offset by the amortization of fair value adjustments over the estimated payout period relating to companies acquired amounting to $2.1 million and the amortization of the deferred charge assets of $5.1 million. The reduction in estimates of net ultimate losses of $25.4 million for the three months ended March 31, 2018 included a net change in case and IBNR reserves of $277.9 million, partially offset by net losses paid of $252.6 million.Atrium

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the Atrium segment:



	Three Months Ended
	March 31,
	2019			2018
Balance as of beginning of period	$	241,284		$	240,873
Less: reinsurance reserves recoverable	38,768			40,531
Net balance as of beginning of period	202,516			200,342
Net incurred losses and LAE:
Current period	18,237			17,306
Prior periods	(1,023		)	(134		)
Total net incurred losses and LAE	17,214			17,172
Net paid losses:
Current period	(7,893		)	(7,154		)
Prior periods	(14,420		)	(10,376		)
Total net paid losses	(22,313		)	(17,530		)
Effect of exchange rate movement	281			786
Net balance as of March 31	197,698			200,770
Plus: reinsurance reserves recoverable	31,682			40,025
Balance as of March 31	$	229,380		$	240,795

Net incurred losses and LAE in the Atrium segment were as follows:



	Three Months Ended March 31,
	2019					2018
	Prior Period		Current Period	Total		Prior Period		Current Period	Total
Net losses paid	14,420		7,893	22,313		10,376		7,154	17,530
Net change in case and LAE reserves	(6,342	)	5,929	(413	)	(2,384	)	6,274	3,890
Net change in IBNR reserves	(10,232	)	4,415	(5,817	)	(5,587	)	3,878	(1,709	)
Increase (reduction) in estimates of net ultimate losses	(2,154	)	18,237	16,083		2,405		17,306	19,711
Amortization of fair value adjustments	1,131		—	1,131		(2,539	)	—	(2,539	)
Net incurred losses and LAE	(1,023	)	18,237	17,214		(134	)	17,306	17,172

StarStone

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for our StarStone segment:



	Three Months Ended
	March 31,
	2019			2018
Balance as of beginning of period	$	1,608,697		$	1,207,743
Less: reinsurance reserves recoverable	462,950			452,017
Net balance as of beginning of period	1,145,747			755,726
Net incurred losses and LAE:
Current period	144,950			77,502
Prior periods	50,102			(2,162		)
Total net incurred losses and LAE	195,052			75,340
Net paid losses:
Current period	(1,792		)	(948		)
Prior periods	(113,625		)	(87,687		)
Total net paid losses	(115,417		)	(88,635		)
Effect of exchange rate movement	(1,291		)	1,538
Assumed business	—			10,268
Net balance as of March 31	1,224,091			754,237
Plus: reinsurance reserves recoverable	466,595			473,527
Balance as of March 31	$	1,690,686		$	1,227,764

Net incurred losses and LAE in the StarStone segment were as follows:



	Three Months Ended March 31,
	2019								2018
	Prior Period			Current Period		Total			Prior Period			Current Period		Total
Net losses paid	$	113,625		$	1,792	$	115,417		$	87,687		$	948	$	88,635
Net change in case and LAE reserves	(8,824		)	10,880		2,056			(14,217		)	9,742		(4,475		)
Net change in IBNR reserves	(52,834		)	129,258		76,424			(73,390		)	64,519		(8,871		)
Increase in estimates of net ultimate losses	51,967			141,930		193,897			80			75,209		75,289
Increase (reduction) in provisions for unallocated LAE	(1,672		)	3,020		1,348			(2,101		)	2,293		192
Amortization of fair value adjustments	(193		)	—		(193		)	(141		)	—		(141		)
Net incurred losses and LAE	$	50,102		$	144,950	$	195,052		$	(2,162	)	$	77,502	$	75,340

Net incurred losses and LAE for the three months ended March 31, 2019 and 2018 were $195.1 million and $75.3 million, respectively. Net adverse prior year loss development was $50.1 million for the three months ended March 31, 2019 compared to net favorable prior year loss development of $2.2 million for the three months ended March 31, 2018. Excluding prior year loss development, net incurred losses and LAE for the three months ended March 31, 2019 and 2018 were $145.0 million and $77.5 million, respectively. Net adverse prior year loss development for the three months ended March 31, 2019 was primarily related to development on lines of business which we have either exited or which are subject to remediation as part of our underwriting repositioning.9. POLICY BENEFITS FOR LIFE CONTRACTS

We have acquired long duration contracts that subject us to mortality, longevity and morbidity risks and which are accounted for as life and annuity premiums earned. Life benefit reserves are established using assumptions for investment yields, mortality, morbidity, lapse and expenses, including a provision for adverse deviation. We establish and review our life reserves regularly based upon cash flow projections. We establish and maintain our life reinsurance reserves at a level that we estimate will, when taken together with future premium payments and investment income expected to be earned on associated premiums, be sufficient to support all future cash flow benefit obligations and third-party servicing obligations as they become payable. Policy benefits for life contracts as of March 31, 2019 and December 31, 2018 were $100.7 million and $105.1 million, respectively. Refer to Note 2 - "Significant Accounting Policies" - (d) Policy Benefits for Life and Annuity Contracts" of the consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2018 for a description of the assumptions used and the process for establishing our assumptions and estimates.

On October 10, 2018, we entered into a Business Transfer Agreement between our wholly-owned subsidiary Alpha and a subsidiary of Monument. This agreement will transfer our remaining life assurance policies written by Alpha to Monument, via a Portfolio Transfer, subject to regulatory approval. The transaction is expected to close during 2019. Our life and annuities operations do not qualify for inclusion in our reportable segments and are therefore included within other activities. The related assets, as well as the results from these operations, were not significant to our consolidated operations and therefore they have not been classified as a discontinued operation. In addition, our proposed transfer of these life assurance polices to Monument was not classified as a held-for-sale business transaction since the underlying contracts do not meet the definition of a business. We have an equity method investment in Monument, as described further in Note 18 - "Related Party Transactions".

Fair Value Measurements

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

8. FAIR VALUE MEASUREMENTSFair 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 investments 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:



	March 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:
Fixed maturity investments:
U.S. government and agency	$	—	$	417,306	$	—	$	—	$	417,306
U.K. government	—		278,443		—		—		278,443
Other government	—		769,976		—		—		769,976
Corporate	—		5,100,843		3,172		—		5,104,015
Municipal	—		160,066		—		—		160,066
Residential mortgage-backed	—		429,005		—		—		429,005
Commercial mortgage-backed	—		884,124		—		—		884,124
Asset-backed	—		687,068		9,300		—		696,368
	$	—	$	8,726,831	$	12,472	$	—	$	8,739,303

Other assets included within funds held - directly managed	74,915		13,681		—		—		88,596

Equities:
Publicly traded equity investments	$	140,398	$	31,312	$	—	$	—	$	171,710
Privately held equity investments	—				228,710		—		228,710
	$	140,398	$	31,312	$	228,710	$	—	$	400,420

Other investments:
Hedge funds	$	—	$	—	$	—	$	979,270	$	979,270
Fixed income funds	—		469,643		—		117,450		587,093
Equity funds	—		108,337		—		265,912		374,249
Private equity funds	—		—		—		235,538		235,538
CLO equities	—		—		41,434		—		41,434
CLO equity fund	—		—		—		40,348		40,348
Private credit funds	—		—		—		53,258		53,258
Others	—		238		313		12,604		13,155
	$	—	$	578,218	$	41,747	$	1,704,380	$	2,324,345
Total Investments	$	215,313	$	9,350,042	$	282,929	$	1,704,380	$	11,552,664

Cash and cash equivalents	$	157,543	$	106,776	$	—	$	—	$	264,319

Reinsurance balances recoverable on paid and unpaid losses:	$	—	$	—	$	735,257	$	—	$	735,257

Other Assets:
Derivative Instruments	$	—	$	5,278	$	—	$	—	$	5,278
	$	—	$	5,278	$	—	$	—	$	5,278

Losses and LAE:	$	—	$	—	$	2,847,793	$	—	$	2,847,793

Other Liabilities:
Derivative Instruments	$	—	$	64	$	—	$	—	$	64
	$	—	$	64	$	—	$	—	$	64



	December 31, 2018
	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:
Fixed maturity investments:
U.S. government and agency	$	—	$	510,245	$	—	$	—	$	510,245
U.K government	—		300,631		—		—		300,631
Other government	—		793,810		—		—		793,810
Corporate	—		4,802,454		37,386		—		4,839,840
Municipal	—		130,265		—		—		130,265
Residential mortgage-backed	—		773,557		—		—		773,557
Commercial mortgage-backed	—		705,674		7,389		—		713,063
Asset-backed	—		627,360		9,121		—		636,481
	$	—	$	8,643,996	$	53,896	$	—	$	8,697,892

Other assets included within funds held - directly managed	$	—	$	14,780	$	—	$	—	$	14,780

Equities:
Publicly traded equity investments	$	102,102	$	36,313	$	—	$	—	$	138,415
Privately held equity investments	—		—		228,710		—		228,710
	$	102,102	$	36,313	$	228,710	$	—	$	367,125

Other investments:
Hedge funds	$	—	$	—	$	—	$	852,584	$	852,584
Fixed income funds	—		290,864		—		112,994		403,858
Equity funds	—		100,440		—		233,241		333,681
Private equity funds	—		—		—		248,628		248,628
CLO equities	—		—		39,052		—		39,052
CLO equity funds	—		—		—		37,260		37,260
Private credit funds	—		—		—		33,381		33,381
Other	—		578		315		8,420		9,313
	$	—	$	391,882	$	39,367	$	1,526,508	$	1,957,757
Total Investments	$	102,102	$	9,086,971	$	321,973	$	1,526,508	$	11,037,554

Cash and cash equivalents	$	243,839	$	21,146	$	—	$	—	$	264,985

Reinsurance recoverable:	$	—	$	—	$	739,591	$	—	$	739,591

Other Assets:
Derivative Instruments	$	—	$	6,701	$	—	$	—	$	6,701
	$	—	$	6,701	$	—	$	—	$	6,701

Losses and LAE:	$	—	$	—	$	2,874,055	$	—	$	2,874,055

Other Liabilities:
Derivative Instruments	$	—	$	983	$	—	$	—	$	983
	$	—	$	983	$	—	$	—	$	983

Valuation Methodologies of Financial Instruments Measured at Fair Value

Fixed Maturity Investments and Funds Held - Directly Managed

The fair values for all securities in the 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 in 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 such other inputs as are available from market sources to determine a reasonable fair value. In addition, pricing services use valuation models, using observable data, such as an Option Adjusted Spread model, to develop prepayment and interest rate scenarios. The Option Adjusted Spread model is commonly used to estimate fair value for securities such as mortgage-backed and asset-backed securities.

The following describes the techniques generally used to determine the fair value of our 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 the major exchanges and are managed by our external advisors. 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. We have categorized the majority of our publicly traded equity investments other than preferred stock 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. The Company uses 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 and their managers. 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 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 our external CLO equity manager. If the investment does not involve an external CLO equity manager, the fair value of the investment is based on valuations provided by the broker or lead underwriter of the investment (the "broker"). Our CLO equity investments 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.

In providing valuations, the CLO equity manager and brokers use observable and unobservable inputs. Of the significant unobservable market inputs used, the default and loss severity rates involve the most judgment and create the most sensitivity. A significant increase or decrease in either of these significant inputs in isolation would result in lower or higher fair value estimates for direct investments in CLO equities and, in general, a change in default rate assumptions will be accompanied by a directionally similar change in loss severity rate assumptions. Collateral spreads and estimated maturity dates are less subjective inputs because they are based on the historical average of actual spreads and the weighted-average life of the current underlying portfolios, respectively. A significant increase or decrease in either of these significant inputs in isolation would result in higher or lower fair value estimates for direct investments in CLO equities. In general, these inputs have no significant interrelationship with each other or with default and loss severity rates.

On a quarterly basis, we receive the valuation from the external CLO manager and brokers and then review the underlying cash flows and key assumptions used by them. We review and update the significant unobservable inputs based on information obtained from secondary markets. These inputs are our responsibility and we assess the reasonableness of the inputs (and if necessary, update the inputs) through communicating with industry participants, monitoring of the transactions in which we participate (for example, to evaluate default and loss severity rate trends), and reviewing market conditions, historical results, and emerging trends that may impact future cash flows.

If valuations from the external CLO equity manager or brokers are not available, we use an income approach based on certain observable and unobservable inputs to value these investments. An income approach is also used to corroborate the reasonableness of the valuations provided by the external manager and brokers. Where an income approach is followed, the valuation is based on available trade information, such as expected cash flows and market assumptions on default and loss severity rates. Other inputs used in the valuation process include asset spreads, loan prepayment speeds, collateral spreads and estimated maturity dates.


•	For our investments in the CLO equity fund, 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 this investment is measured using the NAV as a practical expedient and therefore have not been categorized within the fair value hierarchy.


•	For our investments in private credit 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.

•

Included within other are investments in real estate debt funds, 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 these investments are measured using the NAV as a practical expedient and therefore have not been categorized within the fair value hierarchy.Insurance Contracts - Fair Value OptionThe 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 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 InstrumentsThe fair values of our foreign currency exchange contracts, as described in Note 4 - "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 LevelingTransfers 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:



	Three Months Ended March 31, 2019
	Fixed maturity investments									Privately-held Equities		Other Investments		Total
	Corporate			Commercial mortgage-backed			Asset-backed			Privately-held Equities		Other Investments		Total
Beginning fair value	$	37,386		$	7,389		$	9,121		$	228,710	$	39,367	$	321,973
Sales	(2,660		)	(608		)	(321		)	—		—		(3,589		)
Total realized and unrealized gains	257			62			737			—		2,380		3,436
Transfer into Level 3 from Level 2	387			—			6,225			—		—		6,612
Transfer out of Level 3 into Level 2	(32,198		)	(6,843		)	(6,462		)	—		—		(45,503		)
Ending fair value	$	3,172		$	—		$	9,300		$	228,710	$	41,747	$	282,929



	Three Months Ended March 31, 2018
	Fixed maturity investments												Other Investments			Total
	Corporate			Residential mortgage-backed			Commercial mortgage-backed			Asset-backed			Other Investments			Total
Beginning fair value	$	67,178		$	3,080		$	21,494		$	27,892		$	57,079		$	176,723
Purchases	10,832			—			1,803			1,300			130			14,065
Sales	(7,037		)	(1,148		)	(577		)	(3,804		)	—			(12,566		)
Total realized and unrealized gains (losses)	195			(25		)	83			46			(550		)	(251		)
Transfer into Level 3 from Level 2	15,259			—			4,897			—			—			20,156
Transfer out of Level 3 into Level 2	(400		)	—			(10,066		)	(3,437		)	—			(13,903		)
Ending fair value	$	86,027		$	1,907		$	17,634		$	21,997		$	56,659		$	184,224

Net realized and unrealized gains related to Level 3 assets in the tables above are included in net realized and unrealized gains (losses) in our unaudited condensed 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 us obtaining market observable information regarding the valuations of the specific assets.Insurance Contracts - Fair Value OptionThe following tables present a reconciliation of the beginning and ending balances for all insurance contracts measured at fair value on a recurring basis using Level 3 inputs:



	Three Months Ended
	March 31, 2019									March 31, 2018
	Liability for losses and LAE			Reinsurance balances recoverable			Net			Liability for losses and LAE			Reinsurance balances recoverable			Net
Beginning fair value	$	2,874,055		$	739,591		$	2,134,464		$	1,794,669		$	542,224		$	1,252,445
Assumed business	—			—			—			1,890,061			372,780			1,517,281
Incurred losses and LAE:
Reduction in estimates of ultimate losses	(7,154		)	(3,486		)	(3,668		)	(1,309		)	(1,476		)	167
Reduction in unallocated LAE	(4,341		)	—			(4,341		)	(5,882		)	—			(5,882		)
Change in fair value	77,461			21,420			56,041			(57,155		)	(16,914		)	(40,241		)
Total incurred losses and LAE	65,966			17,934			48,032			(64,346		)	(18,390		)	(45,956		)
Paid losses	(115,860		)	(27,242		)	(88,618		)	(158,372		)	(18,146		)	(140,226		)
Effect of exchange rate movements	23,632			4,974			18,658			57,441			10,268			47,173
Ending fair value	$	2,847,793		$	735,257		$	2,112,536		$	3,519,453		$	888,736		$	2,630,717

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:



	Three Months Ended
	March 31, 2019		March 31, 2018
Changes in fair value due to changes in:
Duration	$	9,047	$	5,540
Corporate bond yield	46,994		(45,781		)
Change in fair value	$	56,041	$	(40,241	)

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:



		March 31, 2019	December 31, 2018
Valuation Technique	Unobservable (U) and Observable (O) Inputs	Weighted Average
Internal model	Corporate bond yield (O)	A rated	A rated
Internal model	Credit spread for non-performance risk (U)	0.2%	0.2%
Internal model	Risk cost of capital (U)	5.1%	5.0%
Internal model	Weighted average cost of capital (U)	8.5%	8.5%
Internal model	Duration - liability (U)	7.40 years	7.33 years
Internal model	Duration - reinsurance balances recoverable (U)	8.01 years	7.98 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

As of March 31, 2019, our 4.5% Senior Notes due 2022 (the "Senior Notes") were carried at amortized cost of $348.2 million while the fair value based on observable market pricing from a third party pricing service was $356.3 million. The Senior Notes are classified as Level 2.

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. 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 March 31, 2019 and December 31, 2018.

- Definition

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.

+ References + Details

Policy Benefits for Life Contracts

3 Months Ended

Mar. 31, 2019

Insurance [Abstract]

POLICY BENEFITS FOR LIFE CONTRACTS



	March 31, 2019
	Non-life Run-off			Atrium		StarStone			Other		Total
Outstanding losses	$	4,624,209		$	86,986	$	824,366		$	6,647	$	5,542,208
IBNR	3,694,932			135,411		840,306			14,335		4,684,984
Fair value adjustments	(209,631		)	4,691		(404		)	—		(205,344		)
Fair value adjustments - fair value option	(300,774		)	—		—			—		(300,774		)
ULAE	346,238			2,292		26,418			—		374,948
Total	$	8,154,974		$	229,380	$	1,690,686		$	20,982	$	10,096,022

Reconciliation to Consolidated Balance Sheet:
Loss and loss adjustment expenses	$	5,307,181		$	229,380	$	1,690,686		$	20,982	$	7,248,229
Loss and loss adjustment expenses, at fair value	2,847,793			—		—			—		2,847,793
Total	$	8,154,974		$	229,380	$	1,690,686		$	20,982	$	10,096,022



	December 31, 2018
	Non-life Run-off			Atrium		StarStone			Other		Total
Outstanding losses	$	4,271,769		$	94,885	$	796,194		$	6,052	$	5,168,900
IBNR	3,527,767			140,521		787,894			12,809		4,468,991
Fair value adjustments	(217,527		)	3,476		(467		)	—		(214,518		)
Fair value adjustments - fair value option	(374,752		)	—		—			—		(374,752		)
ULAE	333,405			2,402		25,076			—		360,883
Total	$	7,540,662		$	241,284	$	1,608,697		$	18,861	$	9,409,504

Reconciliation to Consolidated Balance Sheet:
Loss and loss adjustment expenses	$	4,666,607		$	241,284	$	1,608,697		$	18,861	$	6,535,449
Loss and loss adjustment expenses, at fair value	2,874,055			—		—			—		2,874,055
Total	$	7,540,662		$	241,284	$	1,608,697		$	18,861	$	9,409,504



	Three Months Ended
	March 31,
	2019			2018
Balance as of beginning of period	$	9,409,504		$	7,398,088
Less: reinsurance reserves recoverable	1,867,841			1,870,033
Less: deferred charge assets on retroactive reinsurance	86,585			80,192
Net balance as of beginning of period	7,455,078			5,447,863
Net incurred losses and LAE:
Current period	217,266			95,154
Prior periods	95,138			(75,620)
Total net incurred losses and LAE	312,404			19,534
Net paid losses:
Current period	(28,029		)	(8,103)
Prior periods	(461,605		)	(350,646)
Total net paid losses	(489,634		)	(358,749)
Effect of exchange rate movement	19,679			57,727
Assumed business	620,418			1,527,551
Net balance as of March 31	7,917,945			6,693,926
Plus: reinsurance reserves recoverable	2,077,923			2,217,033
Plus: deferred charge assets on retroactive reinsurance	100,154			75,111
Balance as of March 31	$	10,096,022		$	8,986,070

The tables below provide the net incurred losses and LAE by segment:



	Three Months Ended
	March 31, 2019
	Non-life Run-off			Atrium			StarStone			Other		Total
Net losses paid	$	349,069		$	22,313		$	115,417		$	2,835	$	489,634
Net change in case and LAE reserves	(77,701		)	(413		)	2,056			595		(75,463		)
Net change in IBNR reserves	(232,895		)	(5,817		)	76,424			1,526		(160,762		)
Increase in estimates of net ultimate losses	38,473			16,083			193,897			4,956		253,409
Increase (reduction) in provisions for unallocated LAE	(15,175		)	—			1,348			—		(13,827		)
Amortization of deferred charge assets	7,064			—			—			—		7,064
Amortization of fair value adjustments	8,779			1,131			(193		)	—		9,717
Changes in fair value - fair value option	56,041			—			—			—		56,041
Net incurred losses and LAE	$	95,182		$	17,214		$	195,052		$	4,956	$	312,404



	Three Months Ended
	March 31, 2018
	Non-life Run-off			Atrium			StarStone			Total
Net losses paid	$	252,584		$	17,530		$	88,635		$	358,749
Net change in case and LAE reserves	(123,486		)	3,890			(4,475		)	(124,071		)
Net change in IBNR reserves	(154,111		)	(1,709		)	(8,871		)	(164,691		)
Increase (reduction) in estimates of net ultimate losses	(25,013		)	19,711			75,289			69,987
Increase (reduction) in provisions for unallocated LAE	(14,952		)	—			192			(14,760		)
Amortization of deferred charge assets	5,081			—			—			5,081
Amortization of fair value adjustments	2,147			(2,539		)	(141		)	(533		)
Changes in fair value - fair value option	(40,241		)	—			—			(40,241		)
Net incurred losses and LAE	$	(72,978	)	$	17,172		$	75,340		$	19,534

Non-Life Run-off Segment

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



	Three Months Ended
	March 31,
	2019			2018
Balance as of beginning of period	$	7,540,662		$	5,949,472
Less: reinsurance reserves recoverable	1,366,123			1,377,485
Less: deferred charge assets on retroactive insurance	86,585			80,192
Net balance as of beginning of period	6,087,954			4,491,795
Net incurred losses and LAE:
Current period	49,071			346
Prior periods	46,111			(73,324		)
Total net incurred losses and LAE	95,182			(72,978		)
Net paid losses:
Current period	(18,014		)	(1		)
Prior periods	(331,055		)	(252,583		)
Total net paid losses	(349,069		)	(252,584		)
Effect of exchange rate movement	20,689			55,403
Assumed business	620,418			1,517,283
Net balance as of March 31	6,475,174			5,738,919
Plus: reinsurance reserves recoverable	1,579,646			1,703,481
Plus: deferred charge assets on retroactive reinsurance	100,154			75,111
Balance as of March 31	$	8,154,974		$	7,517,511

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



	Three Months Ended March 31,
	2019								2018
	Prior Period			Current Period		Total			Prior Period			Current Period		Total
Net losses paid	$	331,055		$	18,014	$	349,069		$	252,583		$	1	$	252,584
Net change in case and LAE reserves	(97,573		)	19,872		(77,701		)	(123,492		)	6		(123,486		)
Net change in IBNR reserves	(243,815		)	10,920		(232,895		)	(154,450		)	339		(154,111		)
Increase (reduction) in estimates of net ultimate losses	(10,333		)	48,806		38,473			(25,359		)	346		(25,013		)
Increase (reduction) in provisions for unallocated LAE	(15,440		)	265		(15,175		)	(14,952		)	—		(14,952		)
Amortization of deferred charge assets	7,064			—		7,064			5,081			—		5,081
Amortization of fair value adjustments	8,779			—		8,779			2,147			—		2,147
Changes in fair value - fair value option	56,041			—		56,041			(40,241		)	—		(40,241		)
Net incurred losses and LAE	$	46,111		$	49,071	$	95,182		$	(73,324	)	$	346	$	(72,978	)

Three Months Ended March 31, 2019

Three Months Ended March 31, 2018

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the Atrium segment:



	Three Months Ended
	March 31,
	2019			2018
Balance as of beginning of period	$	241,284		$	240,873
Less: reinsurance reserves recoverable	38,768			40,531
Net balance as of beginning of period	202,516			200,342
Net incurred losses and LAE:
Current period	18,237			17,306
Prior periods	(1,023		)	(134		)
Total net incurred losses and LAE	17,214			17,172
Net paid losses:
Current period	(7,893		)	(7,154		)
Prior periods	(14,420		)	(10,376		)
Total net paid losses	(22,313		)	(17,530		)
Effect of exchange rate movement	281			786
Net balance as of March 31	197,698			200,770
Plus: reinsurance reserves recoverable	31,682			40,025
Balance as of March 31	$	229,380		$	240,795

Net incurred losses and LAE in the Atrium segment were as follows:



	Three Months Ended March 31,
	2019					2018
	Prior Period		Current Period	Total		Prior Period		Current Period	Total
Net losses paid	14,420		7,893	22,313		10,376		7,154	17,530
Net change in case and LAE reserves	(6,342	)	5,929	(413	)	(2,384	)	6,274	3,890
Net change in IBNR reserves	(10,232	)	4,415	(5,817	)	(5,587	)	3,878	(1,709	)
Increase (reduction) in estimates of net ultimate losses	(2,154	)	18,237	16,083		2,405		17,306	19,711
Amortization of fair value adjustments	1,131		—	1,131		(2,539	)	—	(2,539	)
Net incurred losses and LAE	(1,023	)	18,237	17,214		(134	)	17,306	17,172

StarStone

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for our StarStone segment:



	Three Months Ended
	March 31,
	2019			2018
Balance as of beginning of period	$	1,608,697		$	1,207,743
Less: reinsurance reserves recoverable	462,950			452,017
Net balance as of beginning of period	1,145,747			755,726
Net incurred losses and LAE:
Current period	144,950			77,502
Prior periods	50,102			(2,162		)
Total net incurred losses and LAE	195,052			75,340
Net paid losses:
Current period	(1,792		)	(948		)
Prior periods	(113,625		)	(87,687		)
Total net paid losses	(115,417		)	(88,635		)
Effect of exchange rate movement	(1,291		)	1,538
Assumed business	—			10,268
Net balance as of March 31	1,224,091			754,237
Plus: reinsurance reserves recoverable	466,595			473,527
Balance as of March 31	$	1,690,686		$	1,227,764

Net incurred losses and LAE in the StarStone segment were as follows:



	Three Months Ended March 31,
	2019								2018
	Prior Period			Current Period		Total			Prior Period			Current Period		Total
Net losses paid	$	113,625		$	1,792	$	115,417		$	87,687		$	948	$	88,635
Net change in case and LAE reserves	(8,824		)	10,880		2,056			(14,217		)	9,742		(4,475		)
Net change in IBNR reserves	(52,834		)	129,258		76,424			(73,390		)	64,519		(8,871		)
Increase in estimates of net ultimate losses	51,967			141,930		193,897			80			75,209		75,289
Increase (reduction) in provisions for unallocated LAE	(1,672		)	3,020		1,348			(2,101		)	2,293		192
Amortization of fair value adjustments	(193		)	—		(193		)	(141		)	—		(141		)
Net incurred losses and LAE	$	50,102		$	144,950	$	195,052		$	(2,162	)	$	77,502	$	75,340

Premiums Written and Earned

3 Months Ended

Mar. 31, 2019

Insurance [Abstract]

PREMIUMS WRITTEN AND EARNED

5. REINSURANCE BALANCES RECOVERABLE ON PAID AND UNPAID LOSSESThe following tables provide the total reinsurance balances recoverable:



	March 31, 2019
	Non-life Run-off			Atrium		StarStone			Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	1,007,758		$	11,242	$	290,095		$	1,309,095
IBNR	695,921			19,726		178,143			893,790
Fair value adjustments	(14,364		)	714		(1,643		)	(15,293		)
Fair value adjustments - fair value option	(109,669		)	—		—			(109,669		)
Total reinsurance reserves recoverable	1,579,646			31,682		466,595			2,077,923
Paid losses recoverable	170,633			647		37,244			208,524
	$	1,750,279		$	32,329	$	503,839		$	2,286,447
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	1,015,022		$	32,329	$	503,839		$	1,551,190
Reinsurance balances recoverable - fair value option	735,257			—		—			735,257
Total	$	1,750,279		$	32,329	$	503,839		$	2,286,447



	December 31, 2018
	Non-life Run-off			Atrium			StarStone			Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	901,772		$	18,891		$	263,065		$	1,183,728
IBNR	609,434			19,247			201,784			830,465
Fair value adjustments	(14,344		)	630			(1,899		)	(15,613		)
Fair value adjustments - fair value option	(130,739		)	—			—			(130,739		)
Total reinsurance reserves recoverable	1,366,123			38,768			462,950			1,867,841
Paid losses recoverable	138,265			(256		)	23,813			161,822
	$	1,504,388		$	38,512		$	486,763		$	2,029,663
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	764,797		$	38,512		$	486,763		$	1,290,072
Reinsurance balances recoverable - fair value option	739,591			—			—			739,591
Total	$	1,504,388		$	38,512		$	486,763		$	2,029,663



	March 31, 2019
	Non-life Run-off		Atrium		StarStone		Total		% of Total
Top ten reinsurers	$	1,202,892	$	22,421	$	299,058	$	1,524,371	66.7	%
Other reinsurers > $1 million	532,030		8,149		201,709		741,888		32.4	%
Other reinsurers < $1 million	15,357		1,759		3,072		20,188		0.9	%
Total	$	1,750,279	$	32,329	$	503,839	$	2,286,447	100.0	%



	December 31, 2018
	Non-life Run-off		Atrium		StarStone		Total		% of Total
Top ten reinsurers	$	1,124,079	$	25,239	$	263,192	$	1,412,510	69.6	%
Other reinsurers > $1 million	364,098		12,091		220,123		596,312		29.4	%
Other reinsurers < $1 million	16,211		1,182		3,448		20,841		1.0	%
Total	$	1,504,388	$	38,512	$	486,763	$	2,029,663	100.0	%



	March 31, 2019		December 31, 2018
Information regarding top ten reinsurers:
Number of top 10 reinsurers rated A- or better	8		7
Number of top 10 non-rated reinsurers ⁽¹⁾	2		3

Top 10 rated A- or better reinsurers recoverables	$	1,285,067	$	1,096,272
Top 10 collaterized non-rated reinsurers recoverables ⁽¹⁾	239,304		316,238
	$	1,524,371	$	1,412,510

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

Hannover Ruck SE ⁽²⁾	$	297,129	$	279,723
Lloyd's Syndicates ⁽³⁾	$	392,205	$	334,509

⁽²⁾ Hannover Ruck SE is rated AA- by Standard & Poor’s and A+ by A.M. Best.

⁽³⁾ Lloyd's Syndicates are rated A+ by Standard & Poor's and A by A.M. Best. Provisions for Uncollectible Reinsurance Balances Recoverable

We evaluate and monitor concentration of credit risk among our reinsurers, and provisions are made for amounts considered potentially uncollectible.



	March 31, 2019								December 31, 2018
	Gross		Provisions for Bad Debt		Net		Provisions as a % of Gross		Gross		Provisions for Bad Debt		Net		Provisions as a % of Gross
Reinsurers rated A- or above	$	1,883,418	$	54,048	$	1,829,370	2.9	%	$	1,612,464	$	51,519	$	1,560,945	3.2	%
Reinsurers rated below A-, secured	421,205		—		421,205		—	%	430,852		—		430,852		—	%
Reinsurers rated below A-, unsecured	143,303		107,431		35,872		75.0	%	143,079		105,213		37,866		73.5	%
Total	$	2,447,926	$	161,479	$	2,286,447	6.6	%	$	2,186,395	$	156,732	$	2,029,663	7.2	%

10. PREMIUMS WRITTEN AND EARNED

The following table provides a summary of premiums written and earned in our Non-life Run-off, Atrium and StarStone segments and Other activities:



	Three Months Ended March 31,
	2019						2018
	Premiums Written			Premiums Earned			Premiums Written			Premiums Earned
Non-life Run-off
Gross	$	(20,877	)	$	83,966		$	7,380		$	13,110
Ceded	1,699			(7,292		)	(7,280		)	(5,932		)
Net	$	(19,178	)	$	76,674		$	100		$	7,178
Atrium
Gross	$	53,985		$	43,386		$	49,442		$	39,674
Ceded	(7,486		)	(4,633		)	(7,948		)	(4,451		)
Net	$	46,499		$	38,753		$	41,494		$	35,223
StarStone
Gross	$	251,373		$	268,264		$	304,989		$	234,943
Ceded	(56,772		)	(55,002		)	(124,426		)	(108,117		)
Net	$	194,601		$	213,262		$	180,563		$	126,826
Other
Gross	$	864		$	6,673		$	1,037		$	1,050
Ceded	(19		)	(75		)	(47		)	(58		)
Net	$	845		$	6,598		$	990		$	992
Total
Gross	$	285,345		$	402,289		$	362,848		$	288,777
Ceded	(62,578		)	(67,002		)	(139,701		)	(118,558		)
Total	$	222,767		$	335,287		$	223,147		$	170,219

Goodwill and Intangible Assets

3 Months Ended

Mar. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

GOODWILL AND INTANGIBLE ASSETS

11. GOODWILL AND INTANGIBLE ASSETS

The following table presents a reconciliation of the beginning and ending goodwill and intangible assets during the three months ended March 31, 2019:



			Intangible assets
	Goodwill		Intangible assets with a definite life			Intangible assets with an indefinite life		Total			Total
Balance as of January 1, 2019	$	114,807	$	16,887		$	87,031	$	103,918		$	218,725
Amortization	—		(565		)	—		(565		)	(565		)
Balance as of March 31, 2019	$	114,807	$	16,322		$	87,031	$	103,353		$	218,160

Refer to Note 14 - "Goodwill and Intangible Assets" to the consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2018 for more information on goodwill and intangible assets.

The following table provides a summary of the amortization recorded on the intangible assets:



	Three Months Ended March 31,
	2019		2018
Intangible asset amortization	$	565	$	1,266

The gross carrying value, accumulated amortization and net carrying value of intangible assets by type was as follows:



	March 31, 2019							December 31, 2018
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Gross Carrying Value		Accumulated Amortization			Net Carrying Value
Intangible assets with a definite life:
Distribution channel	$	20,000	$	(7,111	)	$	12,889	$	20,000	$	(6,776	)	$	13,224
Technology	15,000		(14,833		)	167		15,000		(14,778		)	222
Brand	7,000		(3,734		)	3,266		7,000		(3,559		)	3,441
Total	$	42,000	$	(25,678	)	$	16,322	$	42,000	$	(25,113	)	$	16,887
Intangible assets with an indefinite life:
Lloyd’s syndicate capacity	$	37,031	$	—		$	37,031	$	37,031	$	—		$	37,031
Licenses	19,900		—			19,900		19,900		—			19,900
Management contract	30,100		—			30,100		30,100		—			30,100
Total	$	87,031	$	—		$	87,031	$	87,031	$	—		$	87,031

Debt Obligations

3 Months Ended

Mar. 31, 2019

Debt Disclosure [Abstract]

DEBT OBLIGATIONS

12. DEBT OBLIGATIONS AND CREDIT FACILITIES

We primarily utilize debt facilities for acquisitions and significant new business and, from time to time, for general corporate purposes. Debt obligations as of March 31, 2019 and December 31, 2018 were as follows:



Facility	Origination Date	Term	March 31, 2019		December 31, 2018
Senior Notes	March 10, 2017	5 years	$	348,180	$	348,054
EGL Revolving Credit Facility	August 16, 2018	5 years	257,000		15,000
2018 EGL Term Loan Facility	December 27, 2018	3 years	498,610		498,485
Total debt obligations			$	1,103,790	$	861,539

The table below provides a summary of the total interest expense:



	Three Months Ended March 31,
	2019		2018
Interest expense on debt obligations	$	10,726	$	7,439
Funds withheld balances and other	310		572
Total interest expense	$	11,036	$	8,011

Senior Notes

On March 10, 2017, we issued Senior Notes for an aggregate principal amount of $350.0 million. The Senior Notes pay 4.5% interest semi-annually and mature on March 10, 2022. The Senior Notes are unsecured and unsubordinated obligations that rank equal to any of our other unsecured and unsubordinated obligations, senior to any future obligations that are expressly subordinated to the Senior Notes, effectively subordinate to any of our secured indebtedness to the extent of the value of the assets securing such indebtedness, and structurally subordinate to all liabilities of our subsidiaries.

The Senior Notes are rated BBB- and are redeemable at our option on a make whole basis at any time prior to the date that is one month prior to the maturity of the Senior Notes. On or after the date that is one month prior to the maturity of the Senior Notes, the Notes are redeemable at a redemption price equal to 100% of the principal amount of the Notes to be redeemed.

We incurred costs of $2.9 million in issuing the Senior Notes. These costs included underwriters’ fees, legal and accounting fees, and other fees, and are capitalized and presented as a direct deduction from the principal amount of debt obligations in the consolidated balance sheets. These costs are amortized over the term of the Senior Notes and are included in interest expense in our consolidated statements of earnings. The unamortized costs as of March 31, 2019 and December 31, 2018 were $1.8 million and $1.9 million, respectively.EGL Revolving Credit Facility

On August 16, 2018, we and certain of our subsidiaries, as borrowers and guarantors, entered into a five-year unsecured $600.0 million revolving credit agreement. The credit agreement expires in August 2023 and we have the option to increase the commitments under the facility by up to an aggregate of $400.0 million. Borrowings under the facility will bear interest at a rate based on the Company's long term senior unsecured debt ratings. In connection with our entry into the credit agreement, we terminated and fully repaid our previous revolving credit agreement, which was originated on September 16, 2014 and was most recently amended on July 17, 2018.

As of March 31, 2019, we were permitted to borrow up to an aggregate of $600.0 million under the facility. As of March 31, 2019, there was $343.0 million of available unutilized capacity under the facility. Subsequent to March 31, 2019, we repaid $42.0 million, bringing the unutilized capacity under this facility to $385.0 million.2018 EGL Term Loan Facility

On December 27, 2018, we entered into and fully utilized a three-year $500.0 million unsecured term loan (the "2018 EGL Term Loan Facility"). The proceeds were partially used to fund the acquisition of Maiden Re North America. We have the option to increase the principal amount of the term loan credit facility up to an aggregate amount of $150 million from the existing lenders or through the addition of new lenders, subject to the terms of the term loan credit agreement.

Interest is payable at least every three months at either ABR or LIBOR plus a margin set forth in the term loan credit agreement. The margin could vary based upon any change in our long term senior unsecured debt rating assigned by S&P or Fitch. During the existence of an event of default, the interest rate may increase and the agent may, and at the request of the required lenders shall, demand early repayment.

We incurred costs of $1.5 million associated with closing the 2018 EGL Term Loan Facility. These costs included bank, legal and accounting fees, and other fees, and are capitalized and presented as a direct deduction from the principal amount of debt obligations in the consolidated balance sheets. These costs are amortized over the term of the facility and are included in interest expense in our consolidated statements of earnings. The unamortized costs as of March 31, 2019 and December 31, 2018 were $1.4 million and $1.5 million, respectively.

Refer to Note 15 - "Debt Obligations and Credit Facilities" of the consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2018 for further information on the terms of the above facilities.Unsecured Letters of CreditWe also utilize unsecured letters of credit for Funds at Lloyd's. On February 8, 2018, we amended and restated our unsecured letter of credit agreement for Funds at Lloyd's ("FAL Facility") to issue up to $325.0 million of letters of credit, with provision to increase the facility up to $400.0 million, subject to lenders approval. On February 12, 2019, we increased the facility up to $375.0 million and maintained the provision to increase the facility to $400.0 million. The FAL Facility is available to satisfy our Funds at Lloyd's requirements and expires in 2022. As of March 31, 2019, our combined Funds at Lloyd's were comprised of cash and investments of $642.1 million and unsecured letters of credit of $368.0 million.

Noncontrolling Interests

3 Months Ended

Mar. 31, 2019

Noncontrolling Interest [Abstract]

NONCONTROLLING INTERESTS

13. NONCONTROLLING INTERESTSRedeemable Noncontrolling Interest

Redeemable noncontrolling interest ("RNCI") as of March 31, 2019 and December 31, 2018 comprises the ownership interests held by the Trident V Funds ("Trident") (39.3%) and Dowling Capital Partners, L.P. ("Dowling") (1.7%) in our subsidiary North Bay Holdings Limited ("North Bay"). North Bay owns our investments in StarStone and Atrium.

The following is a reconciliation of the beginning and ending carrying amount of the equity attributable to the RNCI:



	Three Months Ended			For The Year Ended
	March 31, 2019			December 31, 2018
Balance at beginning of period	$	458,543		$	479,606
Capital contributions	—			55,377
Dividends paid	—			(3,852		)
Net losses attributable to RNCI	(2,544		)	(64,794		)
Accumulated other comprehensive earnings (losses) attributable to RNCI	85			(240		)
Change in redemption value of RNCI	262			(7,554		)
Balance at end of period	$	456,346		$	458,543

We carried the RNCI at its estimated redemption value, which is fair value, as of March 31, 2019. The decrease was primarily attributable to a decrease in the net assets due to net losses related to StarStone during the three months ended March 31, 2019.

Refer to Note 18 - "Related Party Transactions" and Note 19 - "Commitments and Contingencies" for additional information regarding RNCI.Noncontrolling InterestAs of March 31, 2019 and December 31, 2018, we had $12.5 million and $12.1 million, respectively, of noncontrolling interest ("NCI") related to external interests in two of our non-life run-off subsidiaries. A reconciliation of the beginning and ending carrying amount of the equity attributable to NCI is included in the unaudited condensed consolidated statement of changes in shareholders equity.

Share Capital

3 Months Ended

Mar. 31, 2019

Equity [Abstract]

SHARE CAPITAL

14. SHARE CAPITAL

Refer to Note 17 - "Share Capital" in the notes to our consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2018 for additional information on our share capital.

Dividends Declared and Paid

The following table details the dividends that have been declared and paid on our Series D and E Preferred Shares for the period from January 1, 2019 to May 7, 2019:



				Dividend per:
Preferred Share Series	Date Declared	Record Date	Date Payable	Preferred Share		Depositary Share		Total dividends paid and declared in the three months ended March 31, 2019
				(in U.S. dollars)				(in thousands of U.S. dollars)
Series D	February 21, 2019	February 15, 2019	March 1, 2019	$	437.50	$	0.43750	$	7,000
Series E	February 21, 2019	February 15, 2019	March 1, 2019	$	486.11	$	0.48611	2,139
Series D	May 3, 2019	May 15, 2019	June 1, 2019	$	437.50	$	0.43750	—
Series E	May 3, 2019	May 15, 2019	June 1, 2019	$	437.50	$	0.43750	—
								$	9,139

Earnings Per Share

3 Months Ended

Mar. 31, 2019

Earnings Per Share [Abstract]

EARNINGS PER SHARE

15. EARNINGS PER SHARE

The following table sets forth the computation of basic and diluted net earnings per ordinary share:



	Three Months Ended
	March 31,
	2019		2018
Numerator:
Net earnings (loss) attributable to Enstar Group Limited ordinary shareholders	$	358,751	$	(41,210	)
Denominator:
Weighted average ordinary shares outstanding — basic	21,463,499		19,409,021
Effect of dilutive securities:
Share-based compensation plans	122,980		115,630
Warrants	59,383		77,861
Weighted average ordinary shares outstanding — diluted	21,645,862		19,602,512

Earnings (losses) per ordinary share attributable to Enstar Group Limited:
Basic	$	16.71	$	(2.12	)
Diluted⁽¹⁾	$	16.57	$	(2.12	)

(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.

Share-Based Compensation and Pensions

3 Months Ended

Mar. 31, 2019

Retirement Benefits [Abstract]

SHARE-BASED COMPENSATION AND PENSIONS

16. SHARE-BASED COMPENSATION AND PENSIONS

We provide various employee benefits including share-based compensation, an employee share purchase plan, an annual incentive compensation program, and pension plans. These are described in Note 19 - "Share-Based Compensation and Pensions" in the notes to our consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2018.

The table below provides the expenses related to the share-based compensation plans and other share-based compensation plans and pension plans:



	Three Months Ended March 31,
	2019		2018
Share-based compensation plans:
Restricted shares and restricted share units	$	1,843	$	2,349
Performance share units	1,325		2,475
Cash-settled stock appreciation rights	56		1,241
Other share-based compensation plans:
Northshore incentive plan	1,046		1,108
Deferred compensation and ordinary share plan for non-employee directors	827		846
Employee share purchase plan	103		83
Total share-based compensation	$	5,200	$	8,102

The table below provides the expenses related to our pension plans:



	Three Months Ended March 31,
	2019		2018
Pension plans:
Defined contribution plans	$	2,854	$	2,638
Defined benefit plan	175		151
Total pension costs	$	3,029	$	2,789

Income Taxation	3 Months Ended
Income Taxation	Mar. 31, 2019
Income Tax Disclosure [Abstract]
INCOME TAXATION	17. INCOME TAXATIONInterim Tax Calculation MethodWe use the estimated annual effective tax rate method for computing our interim tax provision. This method applies our best estimate of the effective tax rate expected for the full year to our year-to-date earnings before income taxes. We provide for income tax expense or benefit based upon our pre-tax earnings and the provisions of currently enacted tax laws. Certain items deemed to be unusual, infrequent or not reliably estimated are excluded from the estimated annual effective tax rate. In the event such items are identified, the actual tax expense or benefit is reported in the same period as the related item. Certain other items are not included in the estimated annual effective tax rate, such as changes in the assessment of valuation allowance on deferred tax assets and uncertain tax positions, if any.Interim Tax Expense The effective tax rates on income for the three months ended March 31, 2019 and 2018 were 1.3% and (0.4)%, respectively. The effective tax rate on income differs from the statutory rate of 0% due to tax on foreign operations, primarily the United States and the United Kingdom. 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. Deferred income tax liabilities have not been accrued with respect to the undistributed earnings of our foreign subsidiaries. If the earnings were to be distributed, as dividends or other distributions, 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 un-remitted earnings as management has no current intention of remitting these earnings. For our United Kingdom subsidiaries, there are no withholding taxes imposed. For our other foreign subsidiaries, it would not be practicable to compute such amounts 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.Assessment of Valuation Allowance on Deferred Tax AssetWe have estimated the future taxable income of our foreign subsidiaries and have provided a valuation allowance in respect of loss carryforwards where we do not expect to realize a benefit. We have considered all available evidence using a "more than likely than not" standard in determining the amount of the valuation allowance. During the three months ended March 31, 2019, we had no change in our assessment of our valuation allowance on deferred tax assets.Accounting for Uncertainty in Income TaxesThere were no unrecognized tax benefits relating to uncertain tax positions as of March 31, 2019 and December 31, 2018.Tax ExaminationsOur operating subsidiaries may be subject to audit by various tax authorities and may have different statutes of limitations expiration dates. With limited exceptions, our major subsidiaries that operate in the United States, United Kingdom and Australia are no longer subject to tax examinations for years before 2014.

Related Party Transactions

3 Months Ended

Mar. 31, 2019

RELATED PARTY TRANSACTIONS

18. 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 now constitutes approximately 9.1% 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.

In addition, we have entered into certain agreements with Trident with respect to Trident’s co-investments in the Atrium, Arden, and StarStone acquisitions. These include investors’ agreements and shareholders’ agreements, which provide for, among other things: (i) our right to redeem Trident’s equity interest in the StarStone transaction in cash at fair market value within the 90 days following April 1, 2019 (ii) our right to redeem Trident’s equity interest in the Atrium/Arden and StarStone transactions in cash at fair market value at any time following September 6, 2020 and April 1, 2021, respectively; and (iii) Trident’s right to have its equity interest in the Atrium/Arden and StarStone transactions redeemed by us at fair market value (which we may satisfy in either cash or our ordinary shares) following September 6, 2020 and April 1, 2021, respectively. Pursuant to the terms of the shareholders’ agreements, Mr. Carey serves as a Trident representative on the boards of the holding companies established in connection with the Atrium/Arden and StarStone co-investment transactions. Trident also has a second representative on these boards who is a Stone Point employee.

On December 26, 2018, the shareholders of North Bay completed a transaction to provide capital support to StarStone in the form of a contribution to its contributed surplus account and a loss portfolio transfer of certain discontinued and discontinuing lines of business. 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.

The RNCI on our balance sheet relating to these Trident co-investment transactions was as follows:



	March 31, 2019	December 31, 2018
Redeemable Noncontrolling Interest	437,322	439,428

As of March 31, 2019, we had the following relationships with Stone Point and its affiliates:


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


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


•	Separate accounts managed by Eagle Point Credit Management and PRIMA Capital Advisors, 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;


•	Sound Point Capital has acted as collateral manager for certain of our direct investments in CLO 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; and

•

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 Stone Point.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:



	March 31, 2019		December 31, 2018
Investments in funds managed by Stone Point	$	611,262	$	422,771
Investments in registered investment companies affiliated with entities owned by Trident or Stone Point	27,882		32,302
Investments managed by Eagle Point Credit Management and PRIMA Capital Advisors	350,194		176,624
Investments in funds managed by Sound Point Capital	19,889		29,922
Investments in CLO equity securities with Sound Point Capital as collateral manager	13,466		13,449
Separate account managed by Sound Point Capital	115		1,079
Total investments	$	1,022,808	$	676,147

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



	Three Months Ended
	March 31,
	2019			2018
Net unrealized gains (losses) on funds managed by Stone Point	$	24,182		$	(1,526	)
Net unrealized gains (losses) on registered investment companies affiliated with entities owned by Trident or Stone Point	(4,420		)	6,205
Interest income on registered investment companies affiliated with entities owned by Trident	680			1,082
Management fees on investments managed by Eagle Point Credit Management and PRIMA Capital Advisors	(87		)	(227		)
Net unrealized gains (losses) on investments in funds managed by Sound Point Capital	354			(529		)
Net unrealized gains (losses) on investments in CLO equity securities with Sound Point Capital as collateral manager	17			(231		)
Interest income on investments in CLO equity securities with Sound Point Capital as collateral manager	482			1,310
Management fees on separate account managed by Sound Point Capital	—			(81		)
Total net earnings	$	21,208		$	6,003

KaylaReOn December 15, 2016, KaylaRe completed an initial capital raise of $620.0 million. We originally owned approximately 48.2% of KaylaRe's common shares and recorded our investment in KaylaRe using the equity method basis of accounting, as we concluded that we were not required to consolidate based on the guidance in ASC 810 - Consolidation.On May 14, 2018, the Company acquired 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, the Company 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; (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 upon consolidation. Refer to Note 3 - "Acquisitions" in the notes to our consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2018 for additional information.Our subsidiary, Enstar Limited, acts as insurance and reinsurance manager to KaylaRe's subsidiary, KaylaRe Ltd., for which it received fee income. Affiliates of Enstar have also entered into various reinsurance agreements with KaylaRe Ltd. We provide administrative services to KaylaRe and KaylaRe Ltd.

Through a Quota Share Agreement dated December 15, 2016 (the "KaylaRe-StarStone QS"), several of our StarStone affiliates entered into a Quota Share Treaty with KaylaRe Ltd. pursuant to which KaylaRe Ltd. reinsures 35% of all business written by these StarStone affiliates for risks attaching from January 1, 2016, net of the StarStone affiliates’ external reinsurance programs. The reinsurance of StarStone's U.S. and U.K. affiliates was non-renewed as of January 1, 2018 and January 1, 2019, respectively.

In addition, Fitzwilliam Insurance Limited ("Fitzwilliam"), one of our non-life run-off subsidiaries, ceded $177.2 million of loss reserves to KaylaRe Ltd. in 2016. Under the terms of this reinsurance agreement, Fitzwilliam is entitled to receive a profit commission calculated with reference to reserve savings made during the currency of this agreement. Our Non-life Run-off subsidiaries did not cede any additional business to KaylaRe Ltd. during three months ended March 31, 2019 and 2018.Our consolidated statement of earnings included the following amounts related to transactions between us and KaylaRe and KaylaRe Ltd.:



	Three Months Ended
	March 31,
	2018
Management fee income	$	1,397

Transactions under KaylaRe-StarStone QS:
Ceded premium earned	(52,651		)
Net incurred losses	31,543
Acquisition costs	18,774

Total net earnings (loss)	$	(937	)

HillhouseInvestment funds managed by Hillhouse Capital, collectively own approximately 9.7% 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 an approximate 17.0% economic interest in Enstar. Jie Liu, a Partner of Hillhouse Capital, is a member of our Board.As of March 31, 2019 and December 31, 2018 our equity method investee, Enhanzed Re, had investments in a fund managed by Hillhouse Capital, as described below.As of March 31, 2019, our carrying value of the InRe Fund, L.P. ("InRe Fund"), which is managed by Hillhouse Capital, was $793.0 million and the fund was invested in approximately 37% in fixed income securities, 24% in North American equities, 67% in international equities and (28)% in financing, derivatives and other itemsOur consolidated balance sheet included the following balances related to transactions between us and Hillhouse Capital and its affiliated entities:



	March 31, 2019			December 31, 2018
Investments in funds managed by Hillhouse Capital, held by equity method investees	$	212,155		$	75,192
Our ownership of equity method investments	47.4		%	47.4		%
Our indirect investment in funds managed by Hillhouse Capital	$	100,561		$	35,641

Direct investment in funds managed by Hillhouse Capital:
InRe Fund	$	792,980		$	678,420
Other funds	199,732			166,646
	$	992,712		$	845,066

The increase in the direct investment in funds managed by Hillhouse was primarily due to unrealized gains in the first quarter of 2019. We incurred fees of approximately $31.9 million for the three months ended March 31, 2019 in relation to the management of the direct investment in funds managed by Hillhouse Capital and its affiliated entities as described above.MonumentMonument was established in October 2016 and Enstar has invested a total of $26.6 million in the common and preferred shares of Monument. We have approximately a 26.6% interest in Monument. In connection with our investment in Monument, we entered into a Shareholders Agreement with the other shareholders. We recorded the investment in Monument using the equity method basis of accounting, as we concluded that we are not required to consolidate based on the guidance in ASC 810 - Consolidation. On August 29, 2017, we sold our wholly-owned subsidiary Laguna to a subsidiary of Monument. On October 10, 2018, we entered into a Business Transfer Agreement between our wholly-owned subsidiary Alpha Insurance SA and a subsidiary of Monument. This agreement will transfer our remaining life assurance policies to Monument, via a Portfolio Transfer, subject to regulatory approval. The transaction is expected to close in the first half of 2019.Our investment in the common and preferred shares of Monument, carried in equity method investments on our consolidated balance sheet was as follows:



	March 31, 2019		December 31, 2018
Investment in Monument	$	47,746	$	42,193

Clear Spring (formerly SeaBright)Effective January 1, 2017, we sold SeaBright Insurance Company (“SeaBright Insurance”) and its licenses to Delaware Life Insurance Company ("Delaware Life"), a subsidiary of Guggenheim Partners, LLC. Following the sale, SeaBright Insurance was renamed Clear Spring Property and Casualty Company (“Clear Spring”). Clear Spring was subsequently capitalized with $56.0 million of equity, with Enstar retaining a 20% indirect equity interest in Clear Spring.

We have recorded the investment in Clear Spring using the equity method basis of accounting, as we concluded that we are not required to consolidate based on the guidance in ASC 810 - Consolidation. Our investment in the common shares of Clear Spring, carried in equity method investments on our consolidated balance sheet, as of March 31, 2019 and December 31, 2018 was as follows:



	March 31, 2019		December 31, 2018
Investment in Clear Spring	$	10,070	$	10,070

Effective January 1, 2017, StarStone National Insurance Company (“StarStone National”) entered into a 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 a 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.Our consolidated balance sheet included the following balances related to transactions between us and Clear Spring:



	March 31, 2019		December 31, 2018
Balances under StarStone ceding quota share:
Reinsurance balances recoverable	$	26,415	$	23,718
Prepaid insurance premiums	8,527		13,821
Ceded payable	11,830		14,153
Ceded acquisition costs	2,039		3,233

Balances under assuming quota share:
Losses and LAE	6,301		5,778
Unearned reinsurance premiums	2,132		3,455
Funds held	9,833		10,242

Our consolidated statement of earnings included the following amounts related to transactions between us and Clear Spring:



	Three Months Ended
	March 31,
	2019			2018

Transactions under StarStone ceding quota share:
Ceded premium earned	$	(5,485	)	$	(7,003	)
Ceded incurred losses and LAE	3,859			5,562
Ceded acquisition costs	54			1,782

Transactions under assuming quota share:
Premium earned	1,371			1,751
Net incurred losses and LAE	(965		)	(1,390		)
Acquisition costs	(14		)	(464		)

Total net earnings (loss)	$	(1,180	)	$	238

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 approximately 45% of the issued and outstanding shares of common stock of AmTrust Financial Services, Inc. ("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 three separate classes of equity securities issued at the same price and in the same proportion as the equity interest purchased by Trident Pine. Following the closing of the transaction, Enstar owns approximately 7.5% of the equity interest in Evergreen and Trident Pine owns approximately 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 $3.5 million, half of which was payable upon closing and the other on the first anniversary of the closing. The fee was recorded 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 was as follows:



	March 31, 2019		December 31, 2018
Investment in AmTrust	$	200,000	$	200,000

We recorded the following amounts, related to dividend income, included in net earnings related to our investment in AmTrust:



	Three Months Ended
	March 31,
	2019

Net investment income	$	1,821

CitcoIn June 2018, our subsidiary made a $50.0 million indirect investment in the shares of Citco III Limited ("Citco"), a fund administrator with global operations. Pursuant to an investment agreement and in consideration for participation therein, a related party of Hillhouse Capital provided investment support to our subsidiary. 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 March 31, 2019, Trident owned an approximate 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, carried in equity method investments on our consolidated balance sheet, was as follows:



	March 31, 2019		December 31, 2018
Investment in Citco	$	50,917	$	50,812

Enhanzed ReEnhanzed Reinsurance Ltd. ("Enhanzed Re") is a joint venture between Enstar, Allianz SE 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 SE and Enstar. Enstar, Allianz and Hillhouse Capital affiliates have made equity investment commitments in 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 March 31, 2019, Enstar has contributed $94.8 million of its total capital commitment to Enhanzed Re and had an uncalled amount of $128.0 million.Enstar acts as the (re)insurance manager for Enhanzed Re, also Hillhouse Capital acts as primary investment manager, and an affiliate of Allianz SE 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, carried in equity method investments on our consolidated balance sheet was as follows:



	March 31, 2019		December 31, 2018
Investment in EnhanzedRe	$	91,883	$	94,800

We received fee income of $0.1 million from Enhanzed Re, recorded within other income on our consolidated statement of earnings, for the three months ended March 31, 2019.

Commitments and Contingencies

3 Months Ended

Mar. 31, 2019

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

19. COMMITMENTS AND CONTINGENCIESConcentrations 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. Cash, cash equivalents and fixed maturity investments are managed pursuant to guidelines that follow prudent standards of diversification and limit the allowable holdings of a single issue and issuers. Other investments are managed pursuant to guidelines that emphasize diversification and liquidity. Pursuant to these guidelines, we manage and monitor risk across a variety of investment funds and vehicles, markets and counterparties. 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 reinsurance balances recoverable. We remain liable to the extent that retrocessionaires do not meet their contractual obligations and, therefore, we evaluate and monitor concentration of credit risk among our reinsurers. These amounts are discussed in Note 5 - "Reinsurance Balances Recoverable on Paid and Unpaid Losses".

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 balance is credited with investment income and losses payable are deducted. We are subject to credit risk if the reinsured company is unable to honor the value of the funds held balances, such as in the event of insolvency. However, we generally have the contractual ability to offset any shortfall in the payment of the funds held balances with amounts owed by us to the reinsured for losses payable and other amounts contractually due. We routinely monitor the creditworthiness of reinsured companies with whom we have funds held arrangements. We have a significant concentration of $1,101.9 million to one reinsured company which has financial strength credit ratings of A+ from A.M. Best and AA from Standard & Poor's. In connection with the AmTrust RITC transactions, we have recorded, in aggregate $601.9 million as funds held, which is expected to be received in the second quarter of 2019 and subsequently invested in accordance with our investment guidelines.

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 funds held counterparty noted above, exceeded 10% of shareholders’ equity as of March 31, 2019. Our credit exposure to the U.S. government was $711.8 million as of March 31, 2019.Legal ProceedingsWe 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 insurance and reinsurance 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 CommitmentsAs of March 31, 2019, we had unfunded commitments of $210.8 million and $152.3 million to private equity funds and equity method investments, respectively.GuaranteesAs of March 31, 2019 and December 31, 2018, parental guarantees and capital instruments supporting subsidiaries' insurance obligations were $669.6 million and $614.5 million, respectively. We also have a FAL facility, which on February 12, 2019, we increased to issue up to $375.0 million of letters of credit, and maintained the provision to increase the facility up to $400.0 million. The FAL Facility is available to satisfy our Funds at Lloyd’s requirements and expires in 2022. As of March 31, 2019 there were $368.0 million letters of credit issued under this facility which have a parental guarantee.Asbestos Personal Injury Liabilities

We acquired DCo LLC ("DCo") on December 30, 2016, as described in Note 3 - "Acquisitions" of our consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2018. DCo continues to process asbestos personal injury claims in the normal course of business and is separately managed.

Other 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. Other liabilities also include amounts for environmental liabilities associated with DCo's properties.

Other assets 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 provide for the payment of anticipated defense and indemnity costs for pending claims and projected future demands. 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 indemnity and defense costs were paid in full.

Included within other assets and other liabilities are the fair value adjustments that were initially recognized when DCo was acquired. These fair value adjustments continue to be amortized in proportion to the original expected payout patterns for the future 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 was as follows:



	March 31, 2019			December 31, 2018
Other liabilities:
Direct asbestos liabilities	$	262,098		$	265,975
Direct environmental liabilities	2,046			2,152
Estimated future expenses	17,717			19,843
Fair value adjustments	(84,350		)	(84,650		)
	197,511			203,320
Other assets:
Insurance recoveries related to direct asbestos and environmental liabilities	178,100			183,676
Fair value adjustments	(47,669		)	(47,868		)
	130,431			135,808

Net liabilities relating to direct asbestos and environmental exposures	$	67,080		$	67,512

Redeemable Noncontrolling InterestWe 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"). The RNCI rights held by Trident are described in Note 18 - "Related Party Transactions". Dowling has a right to participate if Trident exercises its put right.Leases

We adopted the new leasing standard and the related amendments on January 1, 2019 using the modified retrospective transition method as required by the standard, and based on the detailed analysis of our operating lease arrangements we have recognized a right-of-use asset and an offsetting lease liability on our consolidated balance sheet, 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 38 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. Only those renewal options that we believe we are reasonably certain to exercise are taken into account when determining lease terms. Our lease agreements do not contain any material residual value guarantees or material restrictive covenants.

As most of our leases do not provide an implicit discount rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. We have lease agreements that contain both lease and non-lease components. For real estate leases, we account for lease components together with non-lease components such as common-area maintenance costs as a single lease component.

As part of our adoption of the new leasing standard, we elected the practical expedient package as well as the hindsight practical expedient permitted by the FASB in ASC 842. The practical expedient package covers the application of the new leasing standard to leases that commenced before January 1, 2019, the effective date of the standard and gives an entity the option of not reassessing, (1) whether any expired or existing contracts are or contain leases, (2) the lease classification for any expired or existing leases, and (3) initial direct costs for any existing leases. The hindsight practical expedient permits an entity to consider changes in facts and circumstances from commencement through to the effective date of the new standard when determining the lease term and assessing any potential impairment of the recorded right-of-use asset. All these practical expedients were consistently applied to our leases as required by the leasing standard.

The table below provides a summary of the components of our lease cost including the gross sublease income received under sublease arrangements related to certain office spaces that we have leased to conduct our business operations:



	Three Months Ended March 31,
	2019
Operating lease cost	$	3,487
Sublease income	(131		)
Total lease cost	$	3,356

The table below provides a summary of the cash flow information and non-cash activity related to our operating leases:



	Three Months Ended March 31,
	2019
Operating cash flow information:
Cash paid for amounts included in the measurement of lease liabilities	$	3,024
Non-cash activity:
Right-of-use assets obtained in exchange for lease obligations	$	51,609

The table below provides a summary of the leases recorded on our consolidated balance sheets:



	Balance sheet classification	March 31, 2019
Right-of-use assets	Other assets	$	48,870
Current lease liabilities	Other liabilities	9,063
Non-current lease liabilities	Other liabilities	40,270

Weighted-average remaining lease term and discount rate used for our operating leases are as follows:



	March 31, 2019
Weighted-average remaining lease term	6.6 years
Weighted-average discount rate	6.2	%

The table below provides a summary of the maturity of the operating lease liabilities:



	March 31, 2019
2019	$	8,223
2020	12,469
2021	9,022
2022	7,454
2023	6,605
2024 and beyond	18,010
Total lease payments	61,783
Less: Imputed interest	(12,450		)
Present value of lease liabilities	$	49,333

Segment Information

3 Months Ended

Mar. 31, 2019

Segment Reporting [Abstract]

SEGMENT INFORMATION

20. 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, our remaining life business and other miscellaneous items. These segments are described in Note 1 - "Description of Business" to our consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2018.

The following tables set forth selected and unaudited condensed consolidated statement of earnings results by segment:



	Three Months Ended March 31, 2019
	Non-Life Run-Off			Atrium			StarStone			Other			Total
Gross premiums written	$	(20,877	)	$	53,985		$	251,373		$	864		$	285,345

Net premiums written	$	(19,178	)	$	46,499		$	194,601		$	845		$	222,767

Net premiums earned	$	76,674		$	38,753		$	213,262		$	6,598		$	335,287
Net incurred losses and LAE	(95,182		)	(17,214		)	(195,052		)	(4,956		)	(312,404		)
Life and Annuity Policy Benefits	—			—			—			(96		)	(96		)
Acquisition costs	(28,155		)	(13,742		)	(51,659		)	(232		)	(93,788		)
Operating expenses	(43,992		)	(3,033		)	(35,994		)	—			(83,019		)
Underwriting income (loss)	(90,655		)	4,764			(69,443		)	1,314			(154,020		)
Net investment income (loss)	66,728			1,711			11,942			(1,685		)	78,696
Net realized and unrealized gains	436,186			2,913			20,658			1,034			460,791
Fees and commission income	4,832			1,849			—			—			6,681
Other income	5,504			36			60			212			5,812
Corporate expenses	(16,570		)	(3,788		)	—			(8,697		)	(29,055		)
Interest income (expense)	(12,116		)	—			(475		)	1,555			(11,036		)
Net foreign exchange gains (losses)	3,618			825			(594		)	1			3,850
EARNINGS (LOSS) BEFORE INCOME TAXES	397,527			8,310			(37,852		)	(6,266		)	361,719
Income tax expense	(2,720		)	(685		)	(1,259		)	(85		)	(4,749		)
Earnings from equity method investments	8,584			—			188			—			8,772
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	403,391			7,625			(38,923		)	(6,351		)	365,742
Net loss (earnings) attributable to noncontrolling interest	(2,646		)	(3,128		)	7,922			—			2,148
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED	400,745			4,497			(31,001		)	(6,351		)	367,890
Dividends on preferred shares	—			—			—			(9,139		)	(9,139		)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$	400,745		$	4,497		$	(31,001	)	$	(15,490	)	$	358,751

Underwriting ratios:
Loss ratio				44.4		%	91.5		%
Acquisition expense ratio				35.5		%	24.2		%
Operating expense ratio				7.8		%	16.9		%
Combined ratio				87.7		%	132.6		%



	Three Months Ended March 31, 2018
	Non-Life Run-Off			Atrium			StarStone			Other			Total
Gross premiums written	$	7,380		$	49,442		$	304,989		$	1,037		$	362,848

Net premiums written	$	100		$	41,494		$	180,563		$	990		$	223,147

Net premiums earned	$	7,178		$	35,223		$	126,826		$	992		$	170,219
Net incurred losses and LAE	72,978			(17,172		)	(75,340		)	—			(19,534		)
Life and Annuity Policy Benefits	—			—			—			46			46
Acquisition costs	(1,470		)	(12,065		)	(16,425		)	(148		)	(30,108		)
Operating expenses	(38,403		)	(4,177		)	(34,557		)	—			(77,137		)
Underwriting income	40,283			1,809			504			890			43,486
Net investment income	51,651			1,185			7,701			5,782			66,319
Net realized and unrealized losses	(126,296		)	(1,403		)	(12,958		)	(2,373		)	(143,030		)
Fees and commission income	4,898			3,433			—			—			8,331
Other income (expense)	2,558			64			51			(730		)	1,943
Corporate expenses	(8,633		)	(475		)	—			(9,015		)	(18,123		)
Interest income (expense)	(8,530		)	—			(541		)	1,060			(8,011		)
Net foreign exchange gains (losses)	(7,177		)	(953		)	1,095			1,167			(5,868		)
EARNINGS (LOSS) BEFORE INCOME TAXES	(51,246		)	3,660			(4,148		)	(3,219		)	(54,953		)
Income tax benefit (expense)	1,117			(280		)	(998		)	(11		)	(172		)
Earnings from equity method investments	14,697			—			—			—			14,697
NET EARNINGS (LOSS)	(35,432		)	3,380			(5,146		)	(3,230		)	(40,428		)
Net loss (earnings) attributable to noncontrolling interest	(1,429		)	(1,411		)	2,058			—			(782		)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$	(36,861	)	$	1,969		$	(3,088	)	$	(3,230	)	$	(41,210	)

Underwriting ratios:
Loss ratio				48.8		%	59.4		%
Acquisition expense ratio				34.3		%	13.0		%
Operating expense ratio				11.8		%	27.2		%
Combined ratio				94.9		%	99.6		%

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 by segment were as follows:



	March 31,			December 31,
	2019			2018
Assets by Segment:
Non-life Run-off	$	14,661,681		$	13,362,749
Atrium	588,126			591,722
StarStone	3,464,379			3,416,132
Other	(655,935		)	(814,333		)
Total assets	$	18,058,251		$	16,556,270

Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2019

Accounting Policies [Abstract]

Basis of Preparation

Basis of Consolidation

Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, these financial statements reflect all adjustments consisting of normal recurring items considered necessary for a fair presentation under U.S. GAAP. The results of operations for any interim period are not necessarily indicative of results of the full year. These financial statements should be read in conjunction with the consolidated financial statements and related notes included in our Annual Report on Form 10-K for the year ended December 31, 2018. All significant inter-company transactions and balances have been eliminated. In these notes, the terms "we," "us," "our," or "the Company" refer to Enstar Group Limited and its consolidated subsidiaries.

Reclassifications

Certain prior period amounts have been reclassified to conform to the current period presentation. These reclassifications had no impact on net earnings.

Use of Estimates


•	liability for losses and loss adjustment expenses ("LAE");


•	liability for policy benefits for life contracts;


•	reinsurance balances recoverable on paid and unpaid losses;


•	Valuation allowances on reinsurance balances recoverable and deferred tax assets;


•	impairment charges, including other-than-temporary impairments on investment securities classified as available-for-sale, and impairments on goodwill, intangible assets and deferred charge asset;


•	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.

New Accounting Standards Adopted and Recently Issued Accounting Pronouncements Not Yet Adopted

New Accounting Standards Adopted in 2019

Accounting Standards Update ("ASU") 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income

ASUs 2016-02, 2018-10, 2018-11 and 2019-01, Leases

ASU 2019-04 - Codification Improvements to ASC 326 - Financial Instruments - Credit Losses, ASC 815 - Derivatives and Hedging and ASC 825 - Financial Instruments

Investments (Tables)

3 Months Ended

Mar. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Marketable Securities



	March 31, 2019
	Short-term investments, trading		Fixed maturities, trading		Fixed maturities, available-for-sale		Fixed maturities, funds held - directly managed		Total
U.S. government and agency	$	23,188	$	318,695	$	574	$	74,849	$	417,306
U.K. government	1,238		277,205		—		—		278,443
Other government	5,402		673,155		72,099		19,320		769,976
Corporate	43,662		4,343,019		71,846		645,488		5,104,015
Municipal	—		101,747		2,047		56,272		160,066
Residential mortgage-backed	—		342,891		9		86,105		429,005
Commercial mortgage-backed	—		645,751		—		238,373		884,124
Asset-backed	2,570		614,591		—		79,207		696,368
Total fixed maturity and short-term investments	$	76,060	$	7,317,054	$	146,575	$	1,199,614	$	8,739,303



	December 31, 2018
	Short-term investments, trading		Fixed maturities, trading		Fixed maturities, available-for-sale		Fixed maturities, funds held - directly managed		Total
U.S. government and agency	$	45,885	$	389,735	$	573	$	74,052	$	510,245
U.K. government	2,275		298,356		—		—		300,631
Other government	19,064		679,525		73,185		22,036		793,810
Corporate	44,900		4,081,793		75,359		637,788		4,839,840
Municipal	—		73,856		2,480		53,929		130,265
Residential mortgage-backed	—		682,962		12		90,583		773,557
Commercial mortgage-backed	—		488,598		—		224,465		713,063
Asset-backed	1,992		553,968		—		80,521		636,481
Total fixed maturity and short-term investments	$	114,116	$	7,248,793	$	151,609	$	1,183,374	$	8,697,892

Summary of Amortized Cost and Estimated Fair Value of Fixed Maturities by Contractual Maturity



As of March 31, 2019	Amortized Cost		Fair Value		% of Total Fair Value
One year or less	$	408,671	$	401,606	4.6	%
More than one year through two years	477,168		473,004		5.4	%
More than two years through five years	1,958,078		1,955,798		22.4	%
More than five years through ten years	2,115,535		2,137,694		24.5	%
More than ten years	1,723,351		1,761,704		20.1	%
Residential mortgage-backed	424,195		429,005		4.9	%
Commercial mortgage-backed	884,640		884,124		10.1	%
Asset-backed	698,724		696,368		8.0	%
	$	8,690,362	$	8,739,303	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	$	415,689	$	417,306	4.8	%	$	417,243		$	63		$	—		$	—		$	—		$	—
U.K. government	261,213		278,443		3.2	%	644			277,799			—			—			—			—
Other government	769,300		769,976		8.8	%	308,413			198,228			55,991			171,579			35,765			—
Corporate	5,079,783		5,104,015		58.4	%	132,282			506,434			2,517,323			1,737,171			197,543			13,262
Municipal	156,818		160,066		1.8	%	12,284			81,059			49,814			16,909			—			—
Residential mortgage-backed	424,195		429,005		4.9	%	309,100			55,819			2,054			3,119			51,372			7,541
Commercial mortgage-backed	884,640		884,124		10.1	%	641,337			87,319			77,117			61,139			6,514			10,698
Asset-backed	698,724		696,368		8.0	%	302,491			99,371			164,249			110,806			18,111			1,340
Total	$	8,690,362	$	8,739,303	100.0	%	$	2,123,794		$	1,306,092		$	2,866,548		$	2,100,723		$	309,305		$	32,841
% of total fair value							24.3		%	14.9		%	32.9		%	24.0		%	3.5		%	0.4		%

Amortized Cost and Estimated Fair Values of Company's Fixed Maturity and Short-Term Investments Classified as Available-for-Sale

The amortized cost and fair values of our fixed maturity investments classified as available-for-sale were as follows:



As of March 31, 2019	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses (Non-OTTI)			Fair Value
U.S. government and agency	$	574	$	—	$	—		$	574
Other government	69,918		2,730		(549		)	72,099
Corporate	70,120		2,230		(504		)	71,846
Municipal	2,054		4		(11		)	2,047
Residential mortgage-backed	9		—		—			9
	$	142,675	$	4,964	$	(1,064	)	$	146,575



As of December 31, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses (Non-OTTI)			Fair Value
U.S. government and agency	$	576	$	—	$	(3	)	$	573
Other government	72,811		1,219		(845		)	73,185
Corporate	75,535		1,006		(1,182		)	75,359
Municipal	2,499		—		(19		)	2,480
Residential mortgage-backed	12		—		—			12
	$	151,433	$	2,225	$	(2,049	)	$	151,609

Summary of Investments Classified as Available-for-Sale in Unrealized Loss Position as Well as Aggregate Fair Value and Gross Unrealized Loss by Length of Time

The following tables summarize our fixed maturity investments classified as available-for-sale that are in a gross unrealized loss position:



	12 Months or Greater					Less Than 12 Months					Total
As of March 31, 2019	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Fixed maturity investments, at fair value
Other government	3,570		(318		)	6,260		(231		)	9,830		(549		)
Corporate	12,351		(405		)	4,208		(99		)	16,559		(504		)
Municipal	1,683		(11		)	—		—			1,683		(11		)
Total fixed maturity investments	$	17,604	$	(734	)	$	10,468	$	(330	)	$	28,072	$	(1,064	)



	12 Months or Greater					Less Than 12 Months					Total
As of December 31, 2018	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Fixed maturity investments, at fair value
U.S. government and agency	$	573	$	(3	)	$	—	$	—		$	573	$	(3	)
Other government	7,351		(345		)	11,000		(500		)	18,351		(845		)
Corporate	11,888		(629		)	25,227		(553		)	37,115		(1,182		)
Municipal	1,783		(18		)	283		(1		)	2,066		(19		)
Residential mortgage-backed	12		—			—		—			12		—
Total fixed maturity investments	$	21,607	$	(995	)	$	36,510	$	(1,054	)	$	58,117	$	(2,049	)

Schedule Of Equity Securities, FV-NI

The following table summarizes our equity investments:



	March 31, 2019		December 31, 2018
Publicly traded equity investments in common and preferred stocks	$	171,710	$	138,415
Privately held equity investments in common and preferred stocks	228,710		228,710
	$	400,420	$	367,125

Other Investments

The following table summarizes our other investments carried at fair value:



	March 31, 2019		December 31, 2018
Hedge funds	$	979,270	$	852,584
Fixed income funds	587,093		403,858
Equity funds	374,249		333,681
Private equity funds	235,538		248,628
CLO equities	41,434		39,052
CLO equity fund	40,348		37,260
Private credit funds	53,258		33,381
Other	13,155		9,313
	$	2,324,345	$	1,957,757

Equity Method Investments

The following table summarizes our equity method investments:



	March 31, 2019						December 31, 2018
	Investment		Ownership %		Carrying Value		Investment		Ownership %		Carrying Value
Enhanzed Re	$	94,800	47.4	%	$	91,883	$	94,800	47.4	%	$	94,800
Citco	50,000		31.9	%	50,917		50,000		31.9	%	50,812
Monument	26,600		26.6	%	47,746		26,600		26.6	%	42,193
Clear Spring	11,210		20.0	%	$	10,070	11,210		20.0	%	10,070
Other	25,012		~30%		20,407		15,250		~30%		6,632
	$	207,622			$	221,023	$	197,860			$	204,507

Funds Held, Directly Managed, Carrying Values of Assets

The following table summarizes the components of the funds held - directly managed as of March 31, 2019 and December 31, 2018:



	2019		2018
Fixed maturity investments, trading	$	1,199,614	$	1,183,374
Other assets	88,596		14,780
	$	1,288,210	$	1,198,154

Funds Held, Directly Managed, Fair Value To Amortized Cost

The following table summarizes the fixed maturity investment components of funds held - directly managed as of March 31, 2019 and December 31, 2018:



	March 31, 2019								December 31, 2018
	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
Fixed maturity investments, at amortized cost	$	181,689	$	1,019,636		$	1,201,325		$	179,670		$	1,044,377		$	1,224,047
Net unrealized gains (losses):
Change in fair value - fair value option accounting	978		—			978			(2,733		)	—			(2,733		)
Change in fair value - embedded derivative accounting	—		(2,689		)	(2,689		)	—			(37,940		)	(37,940		)
Fixed maturity investments within funds held - directly managed, at fair value	$	182,667	$	1,016,947		$	1,199,614		$	176,937		$	1,006,437		$	1,183,374

Major Categories of Net Investment Income

Major categories of net investment income are summarized as follows:



	Three Months Ended
	March 31,
	2019			2018
Fixed maturity investments	$	58,070		$	43,888
Short-term investments and cash and cash equivalents	3,860			2,082
Funds held	5,798			3,129
Funds held - directly managed	9,750			8,626
Investment income from fixed maturities and cash and cash equivalents	77,478			57,725
Equity investments	3,380			1,490
Other investments	2,114			3,314
Life settlements and other	—			6,659
Investment income from equities and other investments	5,494			11,463
Gross investment income	82,972			69,188
Investment expenses	(4,276		)	(2,869		)
Net investment income	$	78,696		$	66,319

Realized Gain (Loss) on Investments

Components of net realized and unrealized gains and losses were as follows:



	Three Months Ended
	March 31,
	2019			2018
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, available-for-sale	$	4		$	7
Gross realized losses on fixed maturity securities, available-for-sale	(65		)	(37		)
Net realized losses on fixed maturity securities, trading	(611		)	(6,947		)
Net realized gains (losses) on funds held - directly managed	(1,606		)	96
Net realized gains on equity investments	2,548			903
Total net realized gains (losses) on sale	$	270		$	(5,978	)
Net unrealized gains (losses):
Fixed maturity securities, trading	$	209,467		$	(100,301	)
Fixed maturity securities in funds held - directly managed portfolios	38,962			(30,924		)
Equity investments	7,383			3,835
Other Investments	204,709			(9,662		)
Total net unrealized gains (losses)	460,521			(137,052		)
Net realized and unrealized gains (losses)	$	460,791		$	(143,030	)

Unrealized Gain (Loss) on Investments

Components of net realized and unrealized gains and losses were as follows:



	Three Months Ended
	March 31,
	2019			2018
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, available-for-sale	$	4		$	7
Gross realized losses on fixed maturity securities, available-for-sale	(65		)	(37		)
Net realized losses on fixed maturity securities, trading	(611		)	(6,947		)
Net realized gains (losses) on funds held - directly managed	(1,606		)	96
Net realized gains on equity investments	2,548			903
Total net realized gains (losses) on sale	$	270		$	(5,978	)
Net unrealized gains (losses):
Fixed maturity securities, trading	$	209,467		$	(100,301	)
Fixed maturity securities in funds held - directly managed portfolios	38,962			(30,924		)
Equity investments	7,383			3,835
Other Investments	204,709			(9,662		)
Total net unrealized gains (losses)	460,521			(137,052		)
Net realized and unrealized gains (losses)	$	460,791		$	(143,030	)

Schedule of Restricted Assets

The carrying value of our restricted assets, including restricted cash of $427.6 million and $380.5 million, as of March 31, 2019 and December 31, 2018, respectively, was as follows:



	March 31, 2019		December 31, 2018
Collateral in trust for third party agreements	$	4,276,436	$	4,336,752
Assets on deposit with regulatory authorities	583,780		579,048
Collateral for secured letter of credit facilities	124,576		127,841
Funds at Lloyd's ⁽¹⁾	642,068		354,589
	$	5,626,860	$	5,398,230

Derivative and Hedging Instruments (Tables)

3 Months Ended

Mar. 31, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Estimated Fair Value and Unrealized Gains (Losses) on Derivative Instruments



	March 31, 2019						December 31, 2018
			Fair Value						Fair Value
	Gross Notional Amount		Assets		Liabilities		Gross Notional Amount		Assets		Liabilities
Foreign currency forward - AUD	$	41,874	$	22	$	25	$	42,258	$	1,377	$	—
Foreign currency forward - EUR	115,575		1,568		—		66,422		238		300
Total qualifying hedges	$	157,449	$	1,590	$	25	$	108,680	$	1,615	$	300



	Amount of Gains (Losses) Deferred in AOCI
	Three Months Ended
	March 31,
	2019			2018
Foreign currency forward - AUD	$	(327	)	$	530
Foreign currency forward - EUR	1,855			—
Net gains on qualifying derivative hedges	$	1,528		$	530



	March 31, 2019						December 31, 2018
			Fair Value						Fair Value
	Gross Notional Amount		Assets		Liabilities		Gross Notional Amount		Assets		Liabilities
Foreign currency forward - AUD	$	73,953	$	71	$	25	$	45,427	$	1,952	$	310
Foreign currency forward - CAD	122,690		1,750		—		55,050		1,441		—
Foreign currency forward - EUR	28,389		419		14		54,282		139		301
Foreign currency forward - GBP	224,951		1,448		—		256,959		1,554		72
Total non-qualifying hedges	$	449,983	$	3,688	$	39	$	411,718	$	5,086	$	683



	Gains (Losses) on non-qualifying-hedges included in net earnings
	Three Months Ended March 31,
	2019			2018
Foreign currency forward - AUD	$	(765	)	$	982
Foreign currency forward - CAD	1			2,040
Foreign currency forward - EUR	1,205			(267		)
Foreign currency forward - GBP	(4,059		)	(6,842		)
Net losses on non-qualifying hedges	$	(3,618	)	$	(4,087	)

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 815
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-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=109980867&loc=d3e41620-113959

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(n)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579240-113959

+ Details

Reinsurance Balances Recoverable on Paid and Unpaid Losses (Tables)

3 Months Ended

Mar. 31, 2019

Insurance [Abstract]

Summary of Reinsurance Reserves Recoverable and Uncollectible Reinsurance Balances Recoverable

The following tables provide the total reinsurance balances recoverable:



	March 31, 2019
	Non-life Run-off			Atrium		StarStone			Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	1,007,758		$	11,242	$	290,095		$	1,309,095
IBNR	695,921			19,726		178,143			893,790
Fair value adjustments	(14,364		)	714		(1,643		)	(15,293		)
Fair value adjustments - fair value option	(109,669		)	—		—			(109,669		)
Total reinsurance reserves recoverable	1,579,646			31,682		466,595			2,077,923
Paid losses recoverable	170,633			647		37,244			208,524
	$	1,750,279		$	32,329	$	503,839		$	2,286,447
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	1,015,022		$	32,329	$	503,839		$	1,551,190
Reinsurance balances recoverable - fair value option	735,257			—		—			735,257
Total	$	1,750,279		$	32,329	$	503,839		$	2,286,447



	December 31, 2018
	Non-life Run-off			Atrium			StarStone			Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	901,772		$	18,891		$	263,065		$	1,183,728
IBNR	609,434			19,247			201,784			830,465
Fair value adjustments	(14,344		)	630			(1,899		)	(15,613		)
Fair value adjustments - fair value option	(130,739		)	—			—			(130,739		)
Total reinsurance reserves recoverable	1,366,123			38,768			462,950			1,867,841
Paid losses recoverable	138,265			(256		)	23,813			161,822
	$	1,504,388		$	38,512		$	486,763		$	2,029,663
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	764,797		$	38,512		$	486,763		$	1,290,072
Reinsurance balances recoverable - fair value option	739,591			—			—			739,591
Total	$	1,504,388		$	38,512		$	486,763		$	2,029,663



	March 31, 2019								December 31, 2018
	Gross		Provisions for Bad Debt		Net		Provisions as a % of Gross		Gross		Provisions for Bad Debt		Net		Provisions as a % of Gross
Reinsurers rated A- or above	$	1,883,418	$	54,048	$	1,829,370	2.9	%	$	1,612,464	$	51,519	$	1,560,945	3.2	%
Reinsurers rated below A-, secured	421,205		—		421,205		—	%	430,852		—		430,852		—	%
Reinsurers rated below A-, unsecured	143,303		107,431		35,872		75.0	%	143,079		105,213		37,866		73.5	%
Total	$	2,447,926	$	161,479	$	2,286,447	6.6	%	$	2,186,395	$	156,732	$	2,029,663	7.2	%

The following table provides a summary of premiums written and earned in our Non-life Run-off, Atrium and StarStone segments and Other activities:



	Three Months Ended March 31,
	2019						2018
	Premiums Written			Premiums Earned			Premiums Written			Premiums Earned
Non-life Run-off
Gross	$	(20,877	)	$	83,966		$	7,380		$	13,110
Ceded	1,699			(7,292		)	(7,280		)	(5,932		)
Net	$	(19,178	)	$	76,674		$	100		$	7,178
Atrium
Gross	$	53,985		$	43,386		$	49,442		$	39,674
Ceded	(7,486		)	(4,633		)	(7,948		)	(4,451		)
Net	$	46,499		$	38,753		$	41,494		$	35,223
StarStone
Gross	$	251,373		$	268,264		$	304,989		$	234,943
Ceded	(56,772		)	(55,002		)	(124,426		)	(108,117		)
Net	$	194,601		$	213,262		$	180,563		$	126,826
Other
Gross	$	864		$	6,673		$	1,037		$	1,050
Ceded	(19		)	(75		)	(47		)	(58		)
Net	$	845		$	6,598		$	990		$	992
Total
Gross	$	285,345		$	402,289		$	362,848		$	288,777
Ceded	(62,578		)	(67,002		)	(139,701		)	(118,558		)
Total	$	222,767		$	335,287		$	223,147		$	170,219

Reinsurance Balances Recoverable by Reinsurer



	March 31, 2019
	Non-life Run-off		Atrium		StarStone		Total		% of Total
Top ten reinsurers	$	1,202,892	$	22,421	$	299,058	$	1,524,371	66.7	%
Other reinsurers > $1 million	532,030		8,149		201,709		741,888		32.4	%
Other reinsurers < $1 million	15,357		1,759		3,072		20,188		0.9	%
Total	$	1,750,279	$	32,329	$	503,839	$	2,286,447	100.0	%



	December 31, 2018
	Non-life Run-off		Atrium		StarStone		Total		% of Total
Top ten reinsurers	$	1,124,079	$	25,239	$	263,192	$	1,412,510	69.6	%
Other reinsurers > $1 million	364,098		12,091		220,123		596,312		29.4	%
Other reinsurers < $1 million	16,211		1,182		3,448		20,841		1.0	%
Total	$	1,504,388	$	38,512	$	486,763	$	2,029,663	100.0	%



	March 31, 2019		December 31, 2018
Information regarding top ten reinsurers:
Number of top 10 reinsurers rated A- or better	8		7
Number of top 10 non-rated reinsurers ⁽¹⁾	2		3

Top 10 rated A- or better reinsurers recoverables	$	1,285,067	$	1,096,272
Top 10 collaterized non-rated reinsurers recoverables ⁽¹⁾	239,304		316,238
	$	1,524,371	$	1,412,510

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

Hannover Ruck SE ⁽²⁾	$	297,129	$	279,723
Lloyd's Syndicates ⁽³⁾	$	392,205	$	334,509

⁽²⁾ Hannover Ruck SE is rated AA- by Standard & Poor’s and A+ by A.M. Best.

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

Deferred Charge Assets (Tables)

3 Months Ended

Mar. 31, 2019

Insurance [Abstract]

Deferred Policy Acquisition Costs

The following table presents a reconciliation of the deferred charge assets:



	Three Months Ended March 31,
	2019			2018
Beginning carrying value	$	86,585		$	80,192
Recorded during the period	20,632			—
Amortization	(7,063		)	(5,081		)
Ending carrying value	$	100,154		$	75,111

Losses and Loss Adjustment Expenses (Tables)

3 Months Ended

Mar. 31, 2019

Insurance [Abstract]

Total Losses and Loss Adjustment Expense Liabilities, and Reconciliation of Beginning and Ending Balances

The following table summarizes the liability for losses and LAE by segment:



	March 31, 2019
	Non-life Run-off			Atrium		StarStone			Other		Total
Outstanding losses	$	4,624,209		$	86,986	$	824,366		$	6,647	$	5,542,208
IBNR	3,694,932			135,411		840,306			14,335		4,684,984
Fair value adjustments	(209,631		)	4,691		(404		)	—		(205,344		)
Fair value adjustments - fair value option	(300,774		)	—		—			—		(300,774		)
ULAE	346,238			2,292		26,418			—		374,948
Total	$	8,154,974		$	229,380	$	1,690,686		$	20,982	$	10,096,022

Reconciliation to Consolidated Balance Sheet:
Loss and loss adjustment expenses	$	5,307,181		$	229,380	$	1,690,686		$	20,982	$	7,248,229
Loss and loss adjustment expenses, at fair value	2,847,793			—		—			—		2,847,793
Total	$	8,154,974		$	229,380	$	1,690,686		$	20,982	$	10,096,022



	December 31, 2018
	Non-life Run-off			Atrium		StarStone			Other		Total
Outstanding losses	$	4,271,769		$	94,885	$	796,194		$	6,052	$	5,168,900
IBNR	3,527,767			140,521		787,894			12,809		4,468,991
Fair value adjustments	(217,527		)	3,476		(467		)	—		(214,518		)
Fair value adjustments - fair value option	(374,752		)	—		—			—		(374,752		)
ULAE	333,405			2,402		25,076			—		360,883
Total	$	7,540,662		$	241,284	$	1,608,697		$	18,861	$	9,409,504

Reconciliation to Consolidated Balance Sheet:
Loss and loss adjustment expenses	$	4,666,607		$	241,284	$	1,608,697		$	18,861	$	6,535,449
Loss and loss adjustment expenses, at fair value	2,874,055			—		—			—		2,874,055
Total	$	7,540,662		$	241,284	$	1,608,697		$	18,861	$	9,409,504

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



	Three Months Ended
	March 31,
	2019			2018
Balance as of beginning of period	$	9,409,504		$	7,398,088
Less: reinsurance reserves recoverable	1,867,841			1,870,033
Less: deferred charge assets on retroactive reinsurance	86,585			80,192
Net balance as of beginning of period	7,455,078			5,447,863
Net incurred losses and LAE:
Current period	217,266			95,154
Prior periods	95,138			(75,620)
Total net incurred losses and LAE	312,404			19,534
Net paid losses:
Current period	(28,029		)	(8,103)
Prior periods	(461,605		)	(350,646)
Total net paid losses	(489,634		)	(358,749)
Effect of exchange rate movement	19,679			57,727
Assumed business	620,418			1,527,551
Net balance as of March 31	7,917,945			6,693,926
Plus: reinsurance reserves recoverable	2,077,923			2,217,033
Plus: deferred charge assets on retroactive reinsurance	100,154			75,111
Balance as of March 31	$	10,096,022		$	8,986,070

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



	Three Months Ended
	March 31,
	2019			2018
Balance as of beginning of period	$	7,540,662		$	5,949,472
Less: reinsurance reserves recoverable	1,366,123			1,377,485
Less: deferred charge assets on retroactive insurance	86,585			80,192
Net balance as of beginning of period	6,087,954			4,491,795
Net incurred losses and LAE:
Current period	49,071			346
Prior periods	46,111			(73,324		)
Total net incurred losses and LAE	95,182			(72,978		)
Net paid losses:
Current period	(18,014		)	(1		)
Prior periods	(331,055		)	(252,583		)
Total net paid losses	(349,069		)	(252,584		)
Effect of exchange rate movement	20,689			55,403
Assumed business	620,418			1,517,283
Net balance as of March 31	6,475,174			5,738,919
Plus: reinsurance reserves recoverable	1,579,646			1,703,481
Plus: deferred charge assets on retroactive reinsurance	100,154			75,111
Balance as of March 31	$	8,154,974		$	7,517,511

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the Atrium segment:



	Three Months Ended
	March 31,
	2019			2018
Balance as of beginning of period	$	241,284		$	240,873
Less: reinsurance reserves recoverable	38,768			40,531
Net balance as of beginning of period	202,516			200,342
Net incurred losses and LAE:
Current period	18,237			17,306
Prior periods	(1,023		)	(134		)
Total net incurred losses and LAE	17,214			17,172
Net paid losses:
Current period	(7,893		)	(7,154		)
Prior periods	(14,420		)	(10,376		)
Total net paid losses	(22,313		)	(17,530		)
Effect of exchange rate movement	281			786
Net balance as of March 31	197,698			200,770
Plus: reinsurance reserves recoverable	31,682			40,025
Balance as of March 31	$	229,380		$	240,795

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for our StarStone segment:



	Three Months Ended
	March 31,
	2019			2018
Balance as of beginning of period	$	1,608,697		$	1,207,743
Less: reinsurance reserves recoverable	462,950			452,017
Net balance as of beginning of period	1,145,747			755,726
Net incurred losses and LAE:
Current period	144,950			77,502
Prior periods	50,102			(2,162		)
Total net incurred losses and LAE	195,052			75,340
Net paid losses:
Current period	(1,792		)	(948		)
Prior periods	(113,625		)	(87,687		)
Total net paid losses	(115,417		)	(88,635		)
Effect of exchange rate movement	(1,291		)	1,538
Assumed business	—			10,268
Net balance as of March 31	1,224,091			754,237
Plus: reinsurance reserves recoverable	466,595			473,527
Balance as of March 31	$	1,690,686		$	1,227,764

Schedule of Incurred Losses

The tables below provide the net incurred losses and LAE by segment:



	Three Months Ended
	March 31, 2019
	Non-life Run-off			Atrium			StarStone			Other		Total
Net losses paid	$	349,069		$	22,313		$	115,417		$	2,835	$	489,634
Net change in case and LAE reserves	(77,701		)	(413		)	2,056			595		(75,463		)
Net change in IBNR reserves	(232,895		)	(5,817		)	76,424			1,526		(160,762		)
Increase in estimates of net ultimate losses	38,473			16,083			193,897			4,956		253,409
Increase (reduction) in provisions for unallocated LAE	(15,175		)	—			1,348			—		(13,827		)
Amortization of deferred charge assets	7,064			—			—			—		7,064
Amortization of fair value adjustments	8,779			1,131			(193		)	—		9,717
Changes in fair value - fair value option	56,041			—			—			—		56,041
Net incurred losses and LAE	$	95,182		$	17,214		$	195,052		$	4,956	$	312,404



	Three Months Ended
	March 31, 2018
	Non-life Run-off			Atrium			StarStone			Total
Net losses paid	$	252,584		$	17,530		$	88,635		$	358,749
Net change in case and LAE reserves	(123,486		)	3,890			(4,475		)	(124,071		)
Net change in IBNR reserves	(154,111		)	(1,709		)	(8,871		)	(164,691		)
Increase (reduction) in estimates of net ultimate losses	(25,013		)	19,711			75,289			69,987
Increase (reduction) in provisions for unallocated LAE	(14,952		)	—			192			(14,760		)
Amortization of deferred charge assets	5,081			—			—			5,081
Amortization of fair value adjustments	2,147			(2,539		)	(141		)	(533		)
Changes in fair value - fair value option	(40,241		)	—			—			(40,241		)
Net incurred losses and LAE	$	(72,978	)	$	17,172		$	75,340		$	19,534

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



	Three Months Ended March 31,
	2019								2018
	Prior Period			Current Period		Total			Prior Period			Current Period		Total
Net losses paid	$	331,055		$	18,014	$	349,069		$	252,583		$	1	$	252,584
Net change in case and LAE reserves	(97,573		)	19,872		(77,701		)	(123,492		)	6		(123,486		)
Net change in IBNR reserves	(243,815		)	10,920		(232,895		)	(154,450		)	339		(154,111		)
Increase (reduction) in estimates of net ultimate losses	(10,333		)	48,806		38,473			(25,359		)	346		(25,013		)
Increase (reduction) in provisions for unallocated LAE	(15,440		)	265		(15,175		)	(14,952		)	—		(14,952		)
Amortization of deferred charge assets	7,064			—		7,064			5,081			—		5,081
Amortization of fair value adjustments	8,779			—		8,779			2,147			—		2,147
Changes in fair value - fair value option	56,041			—		56,041			(40,241		)	—		(40,241		)
Net incurred losses and LAE	$	46,111		$	49,071	$	95,182		$	(73,324	)	$	346	$	(72,978	)

Net incurred losses and LAE in the Atrium segment were as follows:



	Three Months Ended March 31,
	2019					2018
	Prior Period		Current Period	Total		Prior Period		Current Period	Total
Net losses paid	14,420		7,893	22,313		10,376		7,154	17,530
Net change in case and LAE reserves	(6,342	)	5,929	(413	)	(2,384	)	6,274	3,890
Net change in IBNR reserves	(10,232	)	4,415	(5,817	)	(5,587	)	3,878	(1,709	)
Increase (reduction) in estimates of net ultimate losses	(2,154	)	18,237	16,083		2,405		17,306	19,711
Amortization of fair value adjustments	1,131		—	1,131		(2,539	)	—	(2,539	)
Net incurred losses and LAE	(1,023	)	18,237	17,214		(134	)	17,306	17,172

Net incurred losses and LAE in the StarStone segment were as follows:



	Three Months Ended March 31,
	2019								2018
	Prior Period			Current Period		Total			Prior Period			Current Period		Total
Net losses paid	$	113,625		$	1,792	$	115,417		$	87,687		$	948	$	88,635
Net change in case and LAE reserves	(8,824		)	10,880		2,056			(14,217		)	9,742		(4,475		)
Net change in IBNR reserves	(52,834		)	129,258		76,424			(73,390		)	64,519		(8,871		)
Increase in estimates of net ultimate losses	51,967			141,930		193,897			80			75,209		75,289
Increase (reduction) in provisions for unallocated LAE	(1,672		)	3,020		1,348			(2,101		)	2,293		192
Amortization of fair value adjustments	(193		)	—		(193		)	(141		)	—		(141		)
Net incurred losses and LAE	$	50,102		$	144,950	$	195,052		$	(2,162	)	$	77,502	$	75,340

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Categorized Investments Recorded at Fair Value among Levels

We have categorized our investments 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:



	March 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:
Fixed maturity investments:
U.S. government and agency	$	—	$	417,306	$	—	$	—	$	417,306
U.K. government	—		278,443		—		—		278,443
Other government	—		769,976		—		—		769,976
Corporate	—		5,100,843		3,172		—		5,104,015
Municipal	—		160,066		—		—		160,066
Residential mortgage-backed	—		429,005		—		—		429,005
Commercial mortgage-backed	—		884,124		—		—		884,124
Asset-backed	—		687,068		9,300		—		696,368
	$	—	$	8,726,831	$	12,472	$	—	$	8,739,303

Other assets included within funds held - directly managed	74,915		13,681		—		—		88,596

Equities:
Publicly traded equity investments	$	140,398	$	31,312	$	—	$	—	$	171,710
Privately held equity investments	—				228,710		—		228,710
	$	140,398	$	31,312	$	228,710	$	—	$	400,420

Other investments:
Hedge funds	$	—	$	—	$	—	$	979,270	$	979,270
Fixed income funds	—		469,643		—		117,450		587,093
Equity funds	—		108,337		—		265,912		374,249
Private equity funds	—		—		—		235,538		235,538
CLO equities	—		—		41,434		—		41,434
CLO equity fund	—		—		—		40,348		40,348
Private credit funds	—		—		—		53,258		53,258
Others	—		238		313		12,604		13,155
	$	—	$	578,218	$	41,747	$	1,704,380	$	2,324,345
Total Investments	$	215,313	$	9,350,042	$	282,929	$	1,704,380	$	11,552,664

Cash and cash equivalents	$	157,543	$	106,776	$	—	$	—	$	264,319

Reinsurance balances recoverable on paid and unpaid losses:	$	—	$	—	$	735,257	$	—	$	735,257

Other Assets:
Derivative Instruments	$	—	$	5,278	$	—	$	—	$	5,278
	$	—	$	5,278	$	—	$	—	$	5,278

Losses and LAE:	$	—	$	—	$	2,847,793	$	—	$	2,847,793

Other Liabilities:
Derivative Instruments	$	—	$	64	$	—	$	—	$	64
	$	—	$	64	$	—	$	—	$	64



	December 31, 2018
	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:
Fixed maturity investments:
U.S. government and agency	$	—	$	510,245	$	—	$	—	$	510,245
U.K government	—		300,631		—		—		300,631
Other government	—		793,810		—		—		793,810
Corporate	—		4,802,454		37,386		—		4,839,840
Municipal	—		130,265		—		—		130,265
Residential mortgage-backed	—		773,557		—		—		773,557
Commercial mortgage-backed	—		705,674		7,389		—		713,063
Asset-backed	—		627,360		9,121		—		636,481
	$	—	$	8,643,996	$	53,896	$	—	$	8,697,892

Other assets included within funds held - directly managed	$	—	$	14,780	$	—	$	—	$	14,780

Equities:
Publicly traded equity investments	$	102,102	$	36,313	$	—	$	—	$	138,415
Privately held equity investments	—		—		228,710		—		228,710
	$	102,102	$	36,313	$	228,710	$	—	$	367,125

Other investments:
Hedge funds	$	—	$	—	$	—	$	852,584	$	852,584
Fixed income funds	—		290,864		—		112,994		403,858
Equity funds	—		100,440		—		233,241		333,681
Private equity funds	—		—		—		248,628		248,628
CLO equities	—		—		39,052		—		39,052
CLO equity funds	—		—		—		37,260		37,260
Private credit funds	—		—		—		33,381		33,381
Other	—		578		315		8,420		9,313
	$	—	$	391,882	$	39,367	$	1,526,508	$	1,957,757
Total Investments	$	102,102	$	9,086,971	$	321,973	$	1,526,508	$	11,037,554

Cash and cash equivalents	$	243,839	$	21,146	$	—	$	—	$	264,985

Reinsurance recoverable:	$	—	$	—	$	739,591	$	—	$	739,591

Other Assets:
Derivative Instruments	$	—	$	6,701	$	—	$	—	$	6,701
	$	—	$	6,701	$	—	$	—	$	6,701

Losses and LAE:	$	—	$	—	$	2,874,055	$	—	$	2,874,055

Other Liabilities:
Derivative Instruments	$	—	$	983	$	—	$	—	$	983
	$	—	$	983	$	—	$	—	$	983

Reconciliation for Assets Measured at Fair Value on a Recurring Basis

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:



	Three Months Ended March 31, 2019
	Fixed maturity investments									Privately-held Equities		Other Investments		Total
	Corporate			Commercial mortgage-backed			Asset-backed			Privately-held Equities		Other Investments		Total
Beginning fair value	$	37,386		$	7,389		$	9,121		$	228,710	$	39,367	$	321,973
Sales	(2,660		)	(608		)	(321		)	—		—		(3,589		)
Total realized and unrealized gains	257			62			737			—		2,380		3,436
Transfer into Level 3 from Level 2	387			—			6,225			—		—		6,612
Transfer out of Level 3 into Level 2	(32,198		)	(6,843		)	(6,462		)	—		—		(45,503		)
Ending fair value	$	3,172		$	—		$	9,300		$	228,710	$	41,747	$	282,929



	Three Months Ended March 31, 2018
	Fixed maturity investments												Other Investments			Total
	Corporate			Residential mortgage-backed			Commercial mortgage-backed			Asset-backed			Other Investments			Total
Beginning fair value	$	67,178		$	3,080		$	21,494		$	27,892		$	57,079		$	176,723
Purchases	10,832			—			1,803			1,300			130			14,065
Sales	(7,037		)	(1,148		)	(577		)	(3,804		)	—			(12,566		)
Total realized and unrealized gains (losses)	195			(25		)	83			46			(550		)	(251		)
Transfer into Level 3 from Level 2	15,259			—			4,897			—			—			20,156
Transfer out of Level 3 into Level 2	(400		)	—			(10,066		)	(3,437		)	—			(13,903		)
Ending fair value	$	86,027		$	1,907		$	17,634		$	21,997		$	56,659		$	184,224

The following tables present a reconciliation of the beginning and ending balances for all insurance contracts measured at fair value on a recurring basis using Level 3 inputs:



	Three Months Ended
	March 31, 2019									March 31, 2018
	Liability for losses and LAE			Reinsurance balances recoverable			Net			Liability for losses and LAE			Reinsurance balances recoverable			Net
Beginning fair value	$	2,874,055		$	739,591		$	2,134,464		$	1,794,669		$	542,224		$	1,252,445
Assumed business	—			—			—			1,890,061			372,780			1,517,281
Incurred losses and LAE:
Reduction in estimates of ultimate losses	(7,154		)	(3,486		)	(3,668		)	(1,309		)	(1,476		)	167
Reduction in unallocated LAE	(4,341		)	—			(4,341		)	(5,882		)	—			(5,882		)
Change in fair value	77,461			21,420			56,041			(57,155		)	(16,914		)	(40,241		)
Total incurred losses and LAE	65,966			17,934			48,032			(64,346		)	(18,390		)	(45,956		)
Paid losses	(115,860		)	(27,242		)	(88,618		)	(158,372		)	(18,146		)	(140,226		)
Effect of exchange rate movements	23,632			4,974			18,658			57,441			10,268			47,173
Ending fair value	$	2,847,793		$	735,257		$	2,112,536		$	3,519,453		$	888,736		$	2,630,717



	Three Months Ended
	March 31, 2019		March 31, 2018
Changes in fair value due to changes in:
Duration	$	9,047	$	5,540
Corporate bond yield	46,994		(45,781		)
Change in fair value	$	56,041	$	(40,241	)

Reconciliation for Liabilities Measured at Fair Value on a Recurring Basis

The following tables present a reconciliation of the beginning and ending balances for all insurance contracts measured at fair value on a recurring basis using Level 3 inputs:



	Three Months Ended
	March 31, 2019									March 31, 2018
	Liability for losses and LAE			Reinsurance balances recoverable			Net			Liability for losses and LAE			Reinsurance balances recoverable			Net
Beginning fair value	$	2,874,055		$	739,591		$	2,134,464		$	1,794,669		$	542,224		$	1,252,445
Assumed business	—			—			—			1,890,061			372,780			1,517,281
Incurred losses and LAE:
Reduction in estimates of ultimate losses	(7,154		)	(3,486		)	(3,668		)	(1,309		)	(1,476		)	167
Reduction in unallocated LAE	(4,341		)	—			(4,341		)	(5,882		)	—			(5,882		)
Change in fair value	77,461			21,420			56,041			(57,155		)	(16,914		)	(40,241		)
Total incurred losses and LAE	65,966			17,934			48,032			(64,346		)	(18,390		)	(45,956		)
Paid losses	(115,860		)	(27,242		)	(88,618		)	(158,372		)	(18,146		)	(140,226		)
Effect of exchange rate movements	23,632			4,974			18,658			57,441			10,268			47,173
Ending fair value	$	2,847,793		$	735,257		$	2,112,536		$	3,519,453		$	888,736		$	2,630,717



	Three Months Ended
	March 31, 2019		March 31, 2018
Changes in fair value due to changes in:
Duration	$	9,047	$	5,540
Corporate bond yield	46,994		(45,781		)
Change in fair value	$	56,041	$	(40,241	)

Quantitative Information

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:



		March 31, 2019	December 31, 2018
Valuation Technique	Unobservable (U) and Observable (O) Inputs	Weighted Average
Internal model	Corporate bond yield (O)	A rated	A rated
Internal model	Credit spread for non-performance risk (U)	0.2%	0.2%
Internal model	Risk cost of capital (U)	5.1%	5.0%
Internal model	Weighted average cost of capital (U)	8.5%	8.5%
Internal model	Duration - liability (U)	7.40 years	7.33 years
Internal model	Duration - reinsurance balances recoverable (U)	8.01 years	7.98 years

Premiums Written and Earned (Tables)

3 Months Ended

Mar. 31, 2019

Insurance [Abstract]

Schedule of Net Premiums Written and Earned

The following tables provide the total reinsurance balances recoverable:



	March 31, 2019
	Non-life Run-off			Atrium		StarStone			Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	1,007,758		$	11,242	$	290,095		$	1,309,095
IBNR	695,921			19,726		178,143			893,790
Fair value adjustments	(14,364		)	714		(1,643		)	(15,293		)
Fair value adjustments - fair value option	(109,669		)	—		—			(109,669		)
Total reinsurance reserves recoverable	1,579,646			31,682		466,595			2,077,923
Paid losses recoverable	170,633			647		37,244			208,524
	$	1,750,279		$	32,329	$	503,839		$	2,286,447
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	1,015,022		$	32,329	$	503,839		$	1,551,190
Reinsurance balances recoverable - fair value option	735,257			—		—			735,257
Total	$	1,750,279		$	32,329	$	503,839		$	2,286,447



	December 31, 2018
	Non-life Run-off			Atrium			StarStone			Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	901,772		$	18,891		$	263,065		$	1,183,728
IBNR	609,434			19,247			201,784			830,465
Fair value adjustments	(14,344		)	630			(1,899		)	(15,613		)
Fair value adjustments - fair value option	(130,739		)	—			—			(130,739		)
Total reinsurance reserves recoverable	1,366,123			38,768			462,950			1,867,841
Paid losses recoverable	138,265			(256		)	23,813			161,822
	$	1,504,388		$	38,512		$	486,763		$	2,029,663
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	764,797		$	38,512		$	486,763		$	1,290,072
Reinsurance balances recoverable - fair value option	739,591			—			—			739,591
Total	$	1,504,388		$	38,512		$	486,763		$	2,029,663



	March 31, 2019								December 31, 2018
	Gross		Provisions for Bad Debt		Net		Provisions as a % of Gross		Gross		Provisions for Bad Debt		Net		Provisions as a % of Gross
Reinsurers rated A- or above	$	1,883,418	$	54,048	$	1,829,370	2.9	%	$	1,612,464	$	51,519	$	1,560,945	3.2	%
Reinsurers rated below A-, secured	421,205		—		421,205		—	%	430,852		—		430,852		—	%
Reinsurers rated below A-, unsecured	143,303		107,431		35,872		75.0	%	143,079		105,213		37,866		73.5	%
Total	$	2,447,926	$	161,479	$	2,286,447	6.6	%	$	2,186,395	$	156,732	$	2,029,663	7.2	%

The following table provides a summary of premiums written and earned in our Non-life Run-off, Atrium and StarStone segments and Other activities:



	Three Months Ended March 31,
	2019						2018
	Premiums Written			Premiums Earned			Premiums Written			Premiums Earned
Non-life Run-off
Gross	$	(20,877	)	$	83,966		$	7,380		$	13,110
Ceded	1,699			(7,292		)	(7,280		)	(5,932		)
Net	$	(19,178	)	$	76,674		$	100		$	7,178
Atrium
Gross	$	53,985		$	43,386		$	49,442		$	39,674
Ceded	(7,486		)	(4,633		)	(7,948		)	(4,451		)
Net	$	46,499		$	38,753		$	41,494		$	35,223
StarStone
Gross	$	251,373		$	268,264		$	304,989		$	234,943
Ceded	(56,772		)	(55,002		)	(124,426		)	(108,117		)
Net	$	194,601		$	213,262		$	180,563		$	126,826
Other
Gross	$	864		$	6,673		$	1,037		$	1,050
Ceded	(19		)	(75		)	(47		)	(58		)
Net	$	845		$	6,598		$	990		$	992
Total
Gross	$	285,345		$	402,289		$	362,848		$	288,777
Ceded	(62,578		)	(67,002		)	(139,701		)	(118,558		)
Total	$	222,767		$	335,287		$	223,147		$	170,219

Goodwill and Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Intangible Assets and Goodwill

The following table presents a reconciliation of the beginning and ending goodwill and intangible assets during the three months ended March 31, 2019:



			Intangible assets
	Goodwill		Intangible assets with a definite life			Intangible assets with an indefinite life		Total			Total
Balance as of January 1, 2019	$	114,807	$	16,887		$	87,031	$	103,918		$	218,725
Amortization	—		(565		)	—		(565		)	(565		)
Balance as of March 31, 2019	$	114,807	$	16,322		$	87,031	$	103,353		$	218,160

Intangible Assets Amortization

The following table provides a summary of the amortization recorded on the intangible assets:



	Three Months Ended March 31,
	2019		2018
Intangible asset amortization	$	565	$	1,266

Schedule of Finite-Lived Intangible Assets

The gross carrying value, accumulated amortization and net carrying value of intangible assets by type was as follows:



	March 31, 2019							December 31, 2018
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Gross Carrying Value		Accumulated Amortization			Net Carrying Value
Intangible assets with a definite life:
Distribution channel	$	20,000	$	(7,111	)	$	12,889	$	20,000	$	(6,776	)	$	13,224
Technology	15,000		(14,833		)	167		15,000		(14,778		)	222
Brand	7,000		(3,734		)	3,266		7,000		(3,559		)	3,441
Total	$	42,000	$	(25,678	)	$	16,322	$	42,000	$	(25,113	)	$	16,887
Intangible assets with an indefinite life:
Lloyd’s syndicate capacity	$	37,031	$	—		$	37,031	$	37,031	$	—		$	37,031
Licenses	19,900		—			19,900		19,900		—			19,900
Management contract	30,100		—			30,100		30,100		—			30,100
Total	$	87,031	$	—		$	87,031	$	87,031	$	—		$	87,031

Schedule of Indefinite-Lived Intangible Assets

The gross carrying value, accumulated amortization and net carrying value of intangible assets by type was as follows:



	March 31, 2019							December 31, 2018
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Gross Carrying Value		Accumulated Amortization			Net Carrying Value
Intangible assets with a definite life:
Distribution channel	$	20,000	$	(7,111	)	$	12,889	$	20,000	$	(6,776	)	$	13,224
Technology	15,000		(14,833		)	167		15,000		(14,778		)	222
Brand	7,000		(3,734		)	3,266		7,000		(3,559		)	3,441
Total	$	42,000	$	(25,678	)	$	16,322	$	42,000	$	(25,113	)	$	16,887
Intangible assets with an indefinite life:
Lloyd’s syndicate capacity	$	37,031	$	—		$	37,031	$	37,031	$	—		$	37,031
Licenses	19,900		—			19,900		19,900		—			19,900
Management contract	30,100		—			30,100		30,100		—			30,100
Total	$	87,031	$	—		$	87,031	$	87,031	$	—		$	87,031

Debt Obligations (Tables)

3 Months Ended

Mar. 31, 2019

Debt Disclosure [Abstract]

Amounts of Loans Payable Outstanding, and Accrued Interest

Debt obligations as of March 31, 2019 and December 31, 2018 were as follows:



Facility	Origination Date	Term	March 31, 2019		December 31, 2018
Senior Notes	March 10, 2017	5 years	$	348,180	$	348,054
EGL Revolving Credit Facility	August 16, 2018	5 years	257,000		15,000
2018 EGL Term Loan Facility	December 27, 2018	3 years	498,610		498,485
Total debt obligations			$	1,103,790	$	861,539

Interest Expense

The table below provides a summary of the total interest expense:



	Three Months Ended March 31,
	2019		2018
Interest expense on debt obligations	$	10,726	$	7,439
Funds withheld balances and other	310		572
Total interest expense	$	11,036	$	8,011

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Noncontrolling Interests (Tables)

3 Months Ended

Mar. 31, 2019

Noncontrolling Interest [Abstract]

Carrying Amount of Equity Attributable to Noncontrolling Interest

The following is a reconciliation of the beginning and ending carrying amount of the equity attributable to the RNCI:



	Three Months Ended			For The Year Ended
	March 31, 2019			December 31, 2018
Balance at beginning of period	$	458,543		$	479,606
Capital contributions	—			55,377
Dividends paid	—			(3,852		)
Net losses attributable to RNCI	(2,544		)	(64,794		)
Accumulated other comprehensive earnings (losses) attributable to RNCI	85			(240		)
Change in redemption value of RNCI	262			(7,554		)
Balance at end of period	$	456,346		$	458,543

Share Capital (Tables)

3 Months Ended

Mar. 31, 2019

Equity [Abstract]

Dividends Declared

The following table details the dividends that have been declared and paid on our Series D and E Preferred Shares for the period from January 1, 2019 to May 7, 2019:



				Dividend per:
Preferred Share Series	Date Declared	Record Date	Date Payable	Preferred Share		Depositary Share		Total dividends paid and declared in the three months ended March 31, 2019
				(in U.S. dollars)				(in thousands of U.S. dollars)
Series D	February 21, 2019	February 15, 2019	March 1, 2019	$	437.50	$	0.43750	$	7,000
Series E	February 21, 2019	February 15, 2019	March 1, 2019	$	486.11	$	0.48611	2,139
Series D	May 3, 2019	May 15, 2019	June 1, 2019	$	437.50	$	0.43750	—
Series E	May 3, 2019	May 15, 2019	June 1, 2019	$	437.50	$	0.43750	—
								$	9,139

Earnings Per Share (Tables)

3 Months Ended

Mar. 31, 2019

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:



	Three Months Ended
	March 31,
	2019		2018
Numerator:
Net earnings (loss) attributable to Enstar Group Limited ordinary shareholders	$	358,751	$	(41,210	)
Denominator:
Weighted average ordinary shares outstanding — basic	21,463,499		19,409,021
Effect of dilutive securities:
Share-based compensation plans	122,980		115,630
Warrants	59,383		77,861
Weighted average ordinary shares outstanding — diluted	21,645,862		19,602,512

Earnings (losses) per ordinary share attributable to Enstar Group Limited:
Basic	$	16.71	$	(2.12	)
Diluted⁽¹⁾	$	16.57	$	(2.12	)

Share-Based Compensation and Pensions (Tables)

3 Months Ended

Mar. 31, 2019

Retirement Benefits [Abstract]

Schedule of Compensation Cost for Share-based Compensation Plans

The table below provides the expenses related to the share-based compensation plans and other share-based compensation plans and pension plans:



	Three Months Ended March 31,
	2019		2018
Share-based compensation plans:
Restricted shares and restricted share units	$	1,843	$	2,349
Performance share units	1,325		2,475
Cash-settled stock appreciation rights	56		1,241
Other share-based compensation plans:
Northshore incentive plan	1,046		1,108
Deferred compensation and ordinary share plan for non-employee directors	827		846
Employee share purchase plan	103		83
Total share-based compensation	$	5,200	$	8,102

The table below provides the expenses related to our pension plans:



	Three Months Ended March 31,
	2019		2018
Pension plans:
Defined contribution plans	$	2,854	$	2,638
Defined benefit plan	175		151
Total pension costs	$	3,029	$	2,789

Related Party Transactions (Tables)

3 Months Ended

Mar. 31, 2019

Schedule of Related Party Transactions

The RNCI on our balance sheet relating to these Trident co-investment transactions was as follows:



	March 31, 2019	December 31, 2018
Redeemable Noncontrolling Interest	437,322	439,428

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:



	March 31, 2019		December 31, 2018
Investments in funds managed by Stone Point	$	611,262	$	422,771
Investments in registered investment companies affiliated with entities owned by Trident or Stone Point	27,882		32,302
Investments managed by Eagle Point Credit Management and PRIMA Capital Advisors	350,194		176,624
Investments in funds managed by Sound Point Capital	19,889		29,922
Investments in CLO equity securities with Sound Point Capital as collateral manager	13,466		13,449
Separate account managed by Sound Point Capital	115		1,079
Total investments	$	1,022,808	$	676,147

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



	Three Months Ended
	March 31,
	2019			2018
Net unrealized gains (losses) on funds managed by Stone Point	$	24,182		$	(1,526	)
Net unrealized gains (losses) on registered investment companies affiliated with entities owned by Trident or Stone Point	(4,420		)	6,205
Interest income on registered investment companies affiliated with entities owned by Trident	680			1,082
Management fees on investments managed by Eagle Point Credit Management and PRIMA Capital Advisors	(87		)	(227		)
Net unrealized gains (losses) on investments in funds managed by Sound Point Capital	354			(529		)
Net unrealized gains (losses) on investments in CLO equity securities with Sound Point Capital as collateral manager	17			(231		)
Interest income on investments in CLO equity securities with Sound Point Capital as collateral manager	482			1,310
Management fees on separate account managed by Sound Point Capital	—			(81		)
Total net earnings	$	21,208		$	6,003

Our consolidated statement of earnings included the following amounts related to transactions between us and KaylaRe and KaylaRe Ltd.:



	Three Months Ended
	March 31,
	2018
Management fee income	$	1,397

Transactions under KaylaRe-StarStone QS:
Ceded premium earned	(52,651		)
Net incurred losses	31,543
Acquisition costs	18,774

Total net earnings (loss)	$	(937	)

Our consolidated balance sheet included the following balances related to transactions between us and Hillhouse Capital and its affiliated entities:



	March 31, 2019			December 31, 2018
Investments in funds managed by Hillhouse Capital, held by equity method investees	$	212,155		$	75,192
Our ownership of equity method investments	47.4		%	47.4		%
Our indirect investment in funds managed by Hillhouse Capital	$	100,561		$	35,641

Direct investment in funds managed by Hillhouse Capital:
InRe Fund	$	792,980		$	678,420
Other funds	199,732			166,646
	$	992,712		$	845,066

Our investment in the common and preferred shares of Monument, carried in equity method investments on our consolidated balance sheet was as follows:



	March 31, 2019		December 31, 2018
Investment in Monument	$	47,746	$	42,193

Our investment in the common shares of Clear Spring, carried in equity method investments on our consolidated balance sheet, as of March 31, 2019 and December 31, 2018 was as follows:



	March 31, 2019		December 31, 2018
Investment in Clear Spring	$	10,070	$	10,070

Our consolidated balance sheet included the following balances related to transactions between us and Clear Spring:



	March 31, 2019		December 31, 2018
Balances under StarStone ceding quota share:
Reinsurance balances recoverable	$	26,415	$	23,718
Prepaid insurance premiums	8,527		13,821
Ceded payable	11,830		14,153
Ceded acquisition costs	2,039		3,233

Balances under assuming quota share:
Losses and LAE	6,301		5,778
Unearned reinsurance premiums	2,132		3,455
Funds held	9,833		10,242

Our consolidated statement of earnings included the following amounts related to transactions between us and Clear Spring:



	Three Months Ended
	March 31,
	2019			2018

Transactions under StarStone ceding quota share:
Ceded premium earned	$	(5,485	)	$	(7,003	)
Ceded incurred losses and LAE	3,859			5,562
Ceded acquisition costs	54			1,782

Transactions under assuming quota share:
Premium earned	1,371			1,751
Net incurred losses and LAE	(965		)	(1,390		)
Acquisition costs	(14		)	(464		)

Total net earnings (loss)	$	(1,180	)	$	238

Our indirect investment in the shares of AmTrust, carried in equities on our consolidated balance sheet was as follows:



	March 31, 2019		December 31, 2018
Investment in AmTrust	$	200,000	$	200,000

We recorded the following amounts, related to dividend income, included in net earnings related to our investment in AmTrust:



	Three Months Ended
	March 31,
	2019

Net investment income	$	1,821

Our indirect investment in the shares of Citco, carried in equity method investments on our consolidated balance sheet, was as follows:



	March 31, 2019		December 31, 2018
Investment in Citco	$	50,917	$	50,812

Our investment in the common shares of Enhanzed Re, carried in equity method investments on our consolidated balance sheet was as follows:



	March 31, 2019		December 31, 2018
Investment in EnhanzedRe	$	91,883	$	94,800

Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2019

Commitments and Contingencies Disclosure [Abstract]

Schedule Of Asbestos And Environmental Liabilities, Insurance Recoveries, Future Estimated Expenses And Fair Value Adjustments

The carrying value of the asbestos and environmental liabilities, insurance recoveries, future estimated expenses and the fair value adjustments related to DCo was as follows:



	March 31, 2019			December 31, 2018
Other liabilities:
Direct asbestos liabilities	$	262,098		$	265,975
Direct environmental liabilities	2,046			2,152
Estimated future expenses	17,717			19,843
Fair value adjustments	(84,350		)	(84,650		)
	197,511			203,320
Other assets:
Insurance recoveries related to direct asbestos and environmental liabilities	178,100			183,676
Fair value adjustments	(47,669		)	(47,868		)
	130,431			135,808

Net liabilities relating to direct asbestos and environmental exposures	$	67,080		$	67,512

Lease, Cost



	Three Months Ended March 31,
	2019
Operating lease cost	$	3,487
Sublease income	(131		)
Total lease cost	$	3,356

The table below provides a summary of the cash flow information and non-cash activity related to our operating leases:



	Three Months Ended March 31,
	2019
Operating cash flow information:
Cash paid for amounts included in the measurement of lease liabilities	$	3,024
Non-cash activity:
Right-of-use assets obtained in exchange for lease obligations	$	51,609

Assets And Liabilities, Lessee

The table below provides a summary of the leases recorded on our consolidated balance sheets:



	Balance sheet classification	March 31, 2019
Right-of-use assets	Other assets	$	48,870
Current lease liabilities	Other liabilities	9,063
Non-current lease liabilities	Other liabilities	40,270

Lessee, Lease Terms

Weighted-average remaining lease term and discount rate used for our operating leases are as follows:



	March 31, 2019
Weighted-average remaining lease term	6.6 years
Weighted-average discount rate	6.2	%

Lessee, Operating Lease, Liability, Maturity

The table below provides a summary of the maturity of the operating lease liabilities:



	March 31, 2019
2019	$	8,223
2020	12,469
2021	9,022
2022	7,454
2023	6,605
2024 and beyond	18,010
Total lease payments	61,783
Less: Imputed interest	(12,450		)
Present value of lease liabilities	$	49,333

Segment Information (Tables)

3 Months Ended

Mar. 31, 2019

Segment Reporting [Abstract]

Summary of Operations by Segment



	Three Months Ended March 31, 2019
	Non-Life Run-Off			Atrium			StarStone			Other			Total
Gross premiums written	$	(20,877	)	$	53,985		$	251,373		$	864		$	285,345

Net premiums written	$	(19,178	)	$	46,499		$	194,601		$	845		$	222,767

Net premiums earned	$	76,674		$	38,753		$	213,262		$	6,598		$	335,287
Net incurred losses and LAE	(95,182		)	(17,214		)	(195,052		)	(4,956		)	(312,404		)
Life and Annuity Policy Benefits	—			—			—			(96		)	(96		)
Acquisition costs	(28,155		)	(13,742		)	(51,659		)	(232		)	(93,788		)
Operating expenses	(43,992		)	(3,033		)	(35,994		)	—			(83,019		)
Underwriting income (loss)	(90,655		)	4,764			(69,443		)	1,314			(154,020		)
Net investment income (loss)	66,728			1,711			11,942			(1,685		)	78,696
Net realized and unrealized gains	436,186			2,913			20,658			1,034			460,791
Fees and commission income	4,832			1,849			—			—			6,681
Other income	5,504			36			60			212			5,812
Corporate expenses	(16,570		)	(3,788		)	—			(8,697		)	(29,055		)
Interest income (expense)	(12,116		)	—			(475		)	1,555			(11,036		)
Net foreign exchange gains (losses)	3,618			825			(594		)	1			3,850
EARNINGS (LOSS) BEFORE INCOME TAXES	397,527			8,310			(37,852		)	(6,266		)	361,719
Income tax expense	(2,720		)	(685		)	(1,259		)	(85		)	(4,749		)
Earnings from equity method investments	8,584			—			188			—			8,772
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	403,391			7,625			(38,923		)	(6,351		)	365,742
Net loss (earnings) attributable to noncontrolling interest	(2,646		)	(3,128		)	7,922			—			2,148
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED	400,745			4,497			(31,001		)	(6,351		)	367,890
Dividends on preferred shares	—			—			—			(9,139		)	(9,139		)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$	400,745		$	4,497		$	(31,001	)	$	(15,490	)	$	358,751

Underwriting ratios:
Loss ratio				44.4		%	91.5		%
Acquisition expense ratio				35.5		%	24.2		%
Operating expense ratio				7.8		%	16.9		%
Combined ratio				87.7		%	132.6		%



	Three Months Ended March 31, 2018
	Non-Life Run-Off			Atrium			StarStone			Other			Total
Gross premiums written	$	7,380		$	49,442		$	304,989		$	1,037		$	362,848

Net premiums written	$	100		$	41,494		$	180,563		$	990		$	223,147

Net premiums earned	$	7,178		$	35,223		$	126,826		$	992		$	170,219
Net incurred losses and LAE	72,978			(17,172		)	(75,340		)	—			(19,534		)
Life and Annuity Policy Benefits	—			—			—			46			46
Acquisition costs	(1,470		)	(12,065		)	(16,425		)	(148		)	(30,108		)
Operating expenses	(38,403		)	(4,177		)	(34,557		)	—			(77,137		)
Underwriting income	40,283			1,809			504			890			43,486
Net investment income	51,651			1,185			7,701			5,782			66,319
Net realized and unrealized losses	(126,296		)	(1,403		)	(12,958		)	(2,373		)	(143,030		)
Fees and commission income	4,898			3,433			—			—			8,331
Other income (expense)	2,558			64			51			(730		)	1,943
Corporate expenses	(8,633		)	(475		)	—			(9,015		)	(18,123		)
Interest income (expense)	(8,530		)	—			(541		)	1,060			(8,011		)
Net foreign exchange gains (losses)	(7,177		)	(953		)	1,095			1,167			(5,868		)
EARNINGS (LOSS) BEFORE INCOME TAXES	(51,246		)	3,660			(4,148		)	(3,219		)	(54,953		)
Income tax benefit (expense)	1,117			(280		)	(998		)	(11		)	(172		)
Earnings from equity method investments	14,697			—			—			—			14,697
NET EARNINGS (LOSS)	(35,432		)	3,380			(5,146		)	(3,230		)	(40,428		)
Net loss (earnings) attributable to noncontrolling interest	(1,429		)	(1,411		)	2,058			—			(782		)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$	(36,861	)	$	1,969		$	(3,088	)	$	(3,230	)	$	(41,210	)

Underwriting ratios:
Loss ratio				48.8		%	59.4		%
Acquisition expense ratio				34.3		%	13.0		%
Operating expense ratio				11.8		%	27.2		%
Combined ratio				94.9		%	99.6		%

Summary of Company's Assets by Segment



	March 31,			December 31,
	2019			2018
Assets by Segment:
Non-life Run-off	$	14,661,681		$	13,362,749
Atrium	588,126			591,722
StarStone	3,464,379			3,416,132
Other	(655,935		)	(814,333		)
Total assets	$	18,058,251		$	16,556,270

Significant Accounting Policies (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets	$ 48,870
Present value of lease liabilities	$ 49,333
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets		$ 51,600
Present value of lease liabilities		$ 51,600

Significant New Business - Additional Information (Detail) $ in Thousands, £ in Millions				3 Months Ended		6 Months Ended	12 Months Ended
	Mar. 01, 2019 USD ($) Agreement	Feb. 14, 2019 USD ($) Agreement	Feb. 14, 2019 GBP (£) Agreement	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Guarantor Obligations [Line Items]
Assumed business				$ 620,418	$ 1,527,551
Deferred charge asset				$ 100,154	$ 75,111			$ 86,585	$ 80,192
Maiden Re Bermuda
Guarantor Obligations [Line Items]
Percentage of business reinsured	100.00%
Number of share agreements \| Agreement	2
Reinsurance premium consideration	$ 500,000
AmTrust RITC
Guarantor Obligations [Line Items]
Assumed business		$ 897,100	£ 703.8
Number of share agreements \| Agreement		4	4
Net loss reserves		$ 620,400	£ 486.8
Cash consideration		688,200	£ 539.9
Deferred charge asset		$ 20,600
Minimum \| Maiden Re Bermuda
Guarantor Obligations [Line Items]
Assumed business	2,440,000
Maximum \| Maiden Re Bermuda
Guarantor Obligations [Line Items]
Assumed business	$ 675,000
Scenario, Forecast \| Zurich
Guarantor Obligations [Line Items]
Assumed business							$ 500,000
Scenario, Forecast \| Amerisure
Guarantor Obligations [Line Items]
Assumed business						$ 60,000
Reinsurance premium consideration						$ 125,000
Percentage of quota share assumed						50.00%

Investments - Asset Types - Fixed Maturity Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	$ 8,739,303
Debt securities, fair value	146,575	$ 151,609
Total fair value	8,739,303	8,697,892
U.S. government and agency
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, fair value	574	573
Total fair value	417,306	510,245
U.K. government
Debt and Equity Securities, FV-NI [Line Items]
Total fair value	278,443	300,631
Other government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, fair value	72,099	73,185
Total fair value	769,976	793,810
Corporate
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, fair value	71,846	75,359
Total fair value	5,104,015	4,839,840
Municipal
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, fair value	2,047	2,480
Total fair value	160,066	130,265
Residential mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, fair value	9	12
Total fair value	429,005	773,557
Commercial mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Total fair value	884,124	713,063
Asset-backed
Debt and Equity Securities, FV-NI [Line Items]
Total fair value	696,368	636,481
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	294,500	656,600
Senior Secured Debt Securities
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	29,100	20,400
Short-term investments, trading
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	76,060	114,116
Short-term investments, trading \| U.S. government and agency
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	23,188	45,885
Short-term investments, trading \| U.K. government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	1,238	2,275
Short-term investments, trading \| Other government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	5,402	19,064
Short-term investments, trading \| Corporate
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	43,662	44,900
Short-term investments, trading \| Municipal
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Short-term investments, trading \| Residential mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Short-term investments, trading \| Commercial mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Short-term investments, trading \| Asset-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	2,570	1,992
Fixed maturity investments
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	7,317,054	7,248,793
Debt securities, fair value	146,575	151,609
Fixed maturity investments \| U.S. government and agency
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	318,695	389,735
Debt securities, fair value	574	573
Fixed maturity investments \| U.K. government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	277,205	298,356
Debt securities, fair value	0	0
Fixed maturity investments \| Other government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	673,155	679,525
Debt securities, fair value	72,099	73,185
Fixed maturity investments \| Corporate
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	4,343,019	4,081,793
Debt securities, fair value	71,846	75,359
Fixed maturity investments \| Municipal
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	101,747	73,856
Debt securities, fair value	2,047	2,480
Fixed maturity investments \| Residential mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	342,891	682,962
Debt securities, fair value	9	12
Fixed maturity investments \| Commercial mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	645,751	488,598
Debt securities, fair value	0	0
Fixed maturity investments \| Asset-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	614,591	553,968
Debt securities, fair value	0	0
Funds held - directly managed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	1,199,614	1,183,374
Funds held - directly managed \| U.S. government and agency
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	74,849	74,052
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	19,320	22,036
Funds held - directly managed \| Corporate
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	645,488	637,788
Funds held - directly managed \| Municipal
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	56,272	53,929
Funds held - directly managed \| Residential mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	86,105	90,583
Funds held - directly managed \| Commercial mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	238,373	224,465
Funds held - directly managed \| Asset-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	$ 79,207	$ 80,521

Investments - Contractual Maturities (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Amortized Cost
One year or less	$ 408,671
More than one year through two years	477,168
More than two years through five years	1,958,078
More than five years through ten years	2,115,535
More than ten years	1,723,351
Trading securities, amortized cost	8,690,362
Fair Value
One year or less	401,606
More than one year through two years	473,004
More than two years through five years	1,955,798
More than five years through ten years	2,137,694
More than ten years	1,761,704
Trading securities, debt	$ 8,739,303
% of Total Fair Value
One year or less	4.60%
More than one year through two years	5.40%
More than two years through five years	22.40%
More than five years through ten years	24.50%
More than ten years	20.10%
Trading securities, percentage of fair value	100.00%
Residential mortgage-backed
Amortized Cost
Securities without single maturity date	$ 424,195
Fair Value
Securities without single maturity date	$ 429,005
% of Total Fair Value
Securities without single maturity date	4.90%
Commercial mortgage-backed
Amortized Cost
Securities without single maturity date	$ 884,640
Fair Value
Securities without single maturity date	$ 884,124
% of Total Fair Value
Securities without single maturity date	10.10%
Asset-backed
Amortized Cost
Securities without single maturity date	$ 698,724
Fair Value
Securities without single maturity date	$ 696,368
% of Total Fair Value
Securities without single maturity date	8.00%

Investments - Available-for-sale Portfolios - Unrealized Gains and Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 142,675	$ 151,433
Gross Unrealized Gains	4,964	2,225
Gross Unrealized Losses Non-OTTI	(1,064)	(2,049)
Debt securities, fair value	146,575	151,609
U.S. government and agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	574	576
Gross Unrealized Gains	0	0
Gross Unrealized Losses Non-OTTI	0	(3)
Debt securities, fair value	574	573
Other government
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	69,918	72,811
Gross Unrealized Gains	2,730	1,219
Gross Unrealized Losses Non-OTTI	(549)	(845)
Debt securities, fair value	72,099	73,185
Corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	70,120	75,535
Gross Unrealized Gains	2,230	1,006
Gross Unrealized Losses Non-OTTI	(504)	(1,182)
Debt securities, fair value	71,846	75,359
Municipal
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,054	2,499
Gross Unrealized Gains	4	0
Gross Unrealized Losses Non-OTTI	(11)	(19)
Debt securities, fair value	2,047	2,480
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	9	12
Gross Unrealized Gains	0	0
Gross Unrealized Losses Non-OTTI	0	0
Debt securities, fair value	$ 9	$ 12

Investments - Gross Unrealized Losses (Detail) $ in Thousands	Mar. 31, 2019 USD ($) Security	Dec. 31, 2018 USD ($) Security
Fair Value
12 Months or Greater	$ 17,604	$ 21,607
Less Than 12 Months	10,468	36,510
Total	28,072	58,117
Gross Unrealized Losses
12 Months or Greater	(734)	(995)
Less Than 12 Months	(330)	(1,054)
Total	$ (1,064)	$ (2,049)
Number of securities classified as available-for-sale in an unrealized loss position \| Security	55	88
Number of securities classified as available-for-sale in an unrealized loss position for twelve months or longer \| Security	43	42
U.S. government and agency
Fair Value
12 Months or Greater		$ 573
Less Than 12 Months		0
Total		573
Gross Unrealized Losses
12 Months or Greater		(3)
Less Than 12 Months		0
Total		(3)
Other government
Fair Value
12 Months or Greater	$ 3,570	7,351
Less Than 12 Months	6,260	11,000
Total	9,830	18,351
Gross Unrealized Losses
12 Months or Greater	(318)	(345)
Less Than 12 Months	(231)	(500)
Total	(549)	(845)
Corporate
Fair Value
12 Months or Greater	12,351	11,888
Less Than 12 Months	4,208	25,227
Total	16,559	37,115
Gross Unrealized Losses
12 Months or Greater	(405)	(629)
Less Than 12 Months	(99)	(553)
Total	(504)	(1,182)
Municipal
Fair Value
12 Months or Greater	1,683	1,783
Less Than 12 Months	0	283
Total	1,683	2,066
Gross Unrealized Losses
12 Months or Greater	(11)	(18)
Less Than 12 Months	0	(1)
Total	$ (11)	(19)
Residential mortgage-backed
Fair Value
12 Months or Greater		12
Less Than 12 Months		0
Total		12
Gross Unrealized Losses
12 Months or Greater		0
Less Than 12 Months		0
Total		$ 0

Investments - Other Than Temporary Impairment (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	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		$ 0

Investments - Equities - Equity Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Investment [Line Items]
Equities, at fair value	$ 400,420	$ 367,125
Publicly traded equity investments in common and preferred stocks
Investment [Line Items]
Equities, at fair value	171,710	138,415
Privately held equity investments in common and preferred stocks
Investment [Line Items]
Equities, at fair value	228,710	228,710
AmTrust Financial Services, Inc.
Investment [Line Items]
Fair value of indirect investment	$ 200,000	$ 200,000

Investments - Other Investments, at Fair Value (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Other Investments [Line Items]
Valuation lag period	3 months
Other investments, at fair value	$ 2,324,345		$ 1,957,757
Additional subscriptions	225,961	$ 275,862
Hedge funds
Other Investments [Line Items]
Investments under redemption restriction	891,600
Other investments, at fair value	$ 979,270		852,584
Fixed income funds
Other Investments [Line Items]
Notice period	30 days
Other investments, at fair value	$ 587,093		403,858
Equity funds
Other Investments [Line Items]
Other investments, at fair value	374,249		333,681
Private equities and private equity funds
Other Investments [Line Items]
Other investments, at fair value	235,538		248,628
Unfunded commitments	210,800
CLO equities
Other Investments [Line Items]
Other investments, at fair value	41,434		39,052
CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	40,348		37,260
Private credit funds
Other Investments [Line Items]
Other investments, at fair value	53,258		33,381
Other
Other Investments [Line Items]
Other investments, at fair value	$ 13,155		$ 9,313
Hedge Funds, Fixed Income
Other Investments [Line Items]
Imposed lock-up period (up to) (years)	3 years
Redemption term	90 days
Investments subject to gates or side-pockets	$ 72,400
Hedge Funds, Equity
Other Investments [Line Items]
Number of days to give notice for semi-annual redemption	60 days
CLO Equity Fund Two
Other Investments [Line Items]
Other investments, at fair value	$ 40,300
Percentage of fund eligible for redemption	28.00%
Other investments
Other Investments [Line Items]
Unrealized gain on investment	$ 204,709	$ (9,662)
Additional subscriptions	$ 167,000
Fixed Income Fund One \| Fixed income funds
Other Investments [Line Items]
Imposed lock-up period (up to) (years)	2 years
Number of days to give notice for semi-annual redemption	65 days
Investments under redemption restriction	$ 43,700
Fixed Income Fund Two \| Fixed income funds
Other Investments [Line Items]
Investments under redemption restriction	$ 73,700

Investments - Equity Method Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Investment	$ 207,622	$ 197,860
Ownership %	47.40%	47.40%
Equity method investments	$ 221,023	$ 204,507
Enhanzed Re
Schedule of Equity Method Investments [Line Items]
Investment	$ 94,800	$ 94,800
Ownership %	47.40%	47.40%
Equity method investments	$ 91,883	$ 94,800
Citco
Schedule of Equity Method Investments [Line Items]
Investment	$ 50,000	$ 50,000
Ownership %	31.90%	31.90%
Equity method investments	$ 50,917	$ 50,812
Monument
Schedule of Equity Method Investments [Line Items]
Investment	$ 26,600	$ 26,600
Ownership %	26.60%	26.60%
Equity method investments	$ 47,746	$ 42,193
Clear Spring
Schedule of Equity Method Investments [Line Items]
Investment	$ 11,210	$ 11,210
Ownership %	20.00%	20.00%
Equity method investments	$ 10,070	$ 10,070
Other
Schedule of Equity Method Investments [Line Items]
Investment	$ 25,012	$ 15,250
Ownership %	30.00%	30.00%
Equity method investments	$ 20,407	$ 6,632
Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Unfunded commitments	$ 152,300

Investments - Funds Held Directly Managed Components (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Funds Held, Directly Managed [Line Items]
Debt securities, trading	$ 8,739,303
Funds held - directly managed	1,288,210	$ 1,198,154
Funds held - directly managed
Schedule of Funds Held, Directly Managed [Line Items]
Debt securities, trading	1,199,614	1,183,374
Funds held - directly managed, other assets	$ 88,596	$ 14,780

Investments - Funds Held Directy Managed - Fixed Maturity Components (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Funds Held, Directly Managed [Line Items]
Fixed maturity investments, at amortized cost	$ 8,690,362
Net unrealized gains (losses):
Debt securities, trading	8,739,303
Funds held - Directly Managed - Fair Value Option
Schedule of Funds Held, Directly Managed [Line Items]
Fixed maturity investments, at amortized cost	181,689	$ 179,670
Net unrealized gains (losses):
Change in fair value - fair value option accounting	978	(2,733)
Change in fair value - embedded derivative accounting	0	0
Debt securities, trading	182,667	176,937
Funds held - Directly Managed - Variable Return
Schedule of Funds Held, Directly Managed [Line Items]
Fixed maturity investments, at amortized cost	1,019,636	1,044,377
Net unrealized gains (losses):
Change in fair value - fair value option accounting	0	0
Change in fair value - embedded derivative accounting	(2,689)	(37,940)
Debt securities, trading	1,016,947	1,006,437
Funds held - directly managed
Schedule of Funds Held, Directly Managed [Line Items]
Fixed maturity investments, at amortized cost	1,201,325	1,224,047
Net unrealized gains (losses):
Change in fair value - fair value option accounting	978	(2,733)
Change in fair value - embedded derivative accounting	(2,689)	(37,940)
Debt securities, trading	$ 1,199,614	$ 1,183,374

Investments - Funds Held Directly Managed Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Investment [Line Items]
Funds held by reinsured companies	$ 919,738	$ 321,267
AmTrust RITC
Investment [Line Items]
Funds held by reinsured companies	$ 601,900

Investments - Net Investment Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net Investment Income [Line Items]
Gross investment income	$ 82,972	$ 69,188
Investment expenses	(4,276)	(2,869)
Net investment income	78,696	66,319
Fixed maturity investments
Net Investment Income [Line Items]
Gross investment income	58,070	43,888
Short-term investments and cash and cash equivalents
Net Investment Income [Line Items]
Gross investment income	3,860	2,082
Funds held
Net Investment Income [Line Items]
Gross investment income	5,798	3,129
Funds held - directly managed
Net Investment Income [Line Items]
Gross investment income	9,750	8,626
Investment income from fixed maturities and cash and cash equivalents
Net Investment Income [Line Items]
Gross investment income	77,478	57,725
Equity securities
Net Investment Income [Line Items]
Gross investment income	3,380	1,490
Other investments
Net Investment Income [Line Items]
Gross investment income	2,114	3,314
Life settlements and other
Net Investment Income [Line Items]
Gross investment income	0	6,659
Investment income from equities and other investments
Net Investment Income [Line Items]
Gross investment income	$ 5,494	$ 11,463

Investments - Net Realized and Unrealized Gains (Losses) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net realized gains (losses) on sale:
Total net realized gains on sale	$ 270	$ (5,978)
Net unrealized gains (losses):
Total net unrealized gains	460,521	(137,052)
Net realized and unrealized gains	460,791	(143,030)
Sales of available-for-sale securities	1,200	7,500
Fixed maturity securities
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, available-for-sale	4	7
Gross realized losses on fixed maturity securities, available-for-sale	(65)	(37)
Net realized gains (losses) on fixed maturity securities	(611)	(6,947)
Net unrealized gains (losses):
Net unrealized gains (losses) on trading securities	209,467	(100,301)
Equity securities
Net realized gains (losses) on sale:
Net realized gains on equity investments	2,548	903
Net unrealized gains (losses):
Equity investments	7,383	3,835
Funds held - directly managed
Net realized gains (losses) on sale:
Net realized gains (losses) on fixed maturity securities	(1,606)	96
Net unrealized gains (losses):
Net unrealized gains (losses) on trading securities	38,962	(30,924)
Other Investments
Net unrealized gains (losses):
Change in fair value of other investments	$ 204,709	$ (9,662)

Investments - Restricted Assets (Detail) $ in Thousands	3 Months Ended
Investments - Restricted Assets (Detail) $ in Thousands	Mar. 31, 2019 USD ($) Segment	Dec. 31, 2018 USD ($)	Mar. 31, 2018 USD ($)
Line of Credit Facility [Line Items]
Restricted cash and cash equivalents	$ 427,601	$ 380,488	$ 483,136
Collateral in trust for third party agreements	4,276,436	4,336,752
Assets on deposit with regulatory authorities	583,780	579,048
Funds at Lloyd's	642,068	354,589
Restricted assets, total	$ 5,626,860	5,398,230
Number of syndicates \| Segment	3
Asset Pledged as Collateral
Line of Credit Facility [Line Items]
Collateral for secured letter of credit facilities	$ 124,576	$ 127,841

Derivative and Hedging Instruments - Foreign Currency Hedging of Net Investments (Detail) $ in Thousands, € in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Mar. 31, 2018 EUR (€)
Derivative [Line Items]
Total cumulative translation adjustment	$ 801	$ (1,225)
Designated as Hedging Instrument \| Foreign exchange forward
Derivative [Line Items]
Gross Notional Amount	157,449		$ 108,680
Assets	1,590		1,615
Liabilities	25		300
Net gains on qualifying derivative hedges	1,528	530
Designated as Hedging Instrument \| Foreign exchange forward \| AUD
Derivative [Line Items]
Gross Notional Amount	41,874		42,258
Assets	22		1,377
Liabilities	25		0
Net gains on qualifying derivative hedges	(327)	530
Designated as Hedging Instrument \| Foreign exchange forward \| EUR
Derivative [Line Items]
Gross Notional Amount	115,575		66,422
Assets	1,568		238
Liabilities	0		300
Net gains on qualifying derivative hedges	1,855	0
Not designated as hedging instrument \| Foreign exchange forward
Derivative [Line Items]
Gross Notional Amount	449,983		411,718
Assets	3,688		5,086
Liabilities	39		683
Gains (Losses) on non-qualifying-hedges included in net earnings	(3,618)	(4,087)
Not designated as hedging instrument \| Foreign exchange forward \| AUD
Derivative [Line Items]
Gross Notional Amount	73,953		45,427
Assets	71		1,952
Liabilities	25		310
Gains (Losses) on non-qualifying-hedges included in net earnings	(765)	982
Not designated as hedging instrument \| Foreign exchange forward \| CAD
Derivative [Line Items]
Gross Notional Amount	122,690		55,050
Assets	1,750		1,441
Liabilities	0		0
Gains (Losses) on non-qualifying-hedges included in net earnings	1	2,040
Not designated as hedging instrument \| Foreign exchange forward \| EUR
Derivative [Line Items]
Gross Notional Amount	28,389		54,282
Assets	419		139
Liabilities	14		301
Gains (Losses) on non-qualifying-hedges included in net earnings	1,205	(267)
Not designated as hedging instrument \| Foreign exchange forward \| GBP
Derivative [Line Items]
Gross Notional Amount	224,951		256,959
Assets	1,448		1,554
Liabilities	0		$ 72
Gains (Losses) on non-qualifying-hedges included in net earnings	$ (4,059)	(6,842)
Net Investment Hedging
Derivative [Line Items]
Gross Notional Amount		73,700		€ 60.0
Total cumulative translation adjustment		$ 1,200

Derivative and Hedging Instruments - Investments in Call Options on Equities (Details) - Not designated as hedging instrument - Call options on equity - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Derivative [Line Items]
Unrealized gain (loss) on equity securities	$ (0.2)	$ (2.5)
Cost		10.0
Fair value of derivatives		$ 0.2	$ 0.4

Reinsurance Balances Recoverable on Paid and Unpaid Losses - Total Reinsurance Balances (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Effects of Reinsurance [Line Items]
Outstanding losses	$ 1,309,095	$ 1,183,728
IBNR	893,790	830,465
Fair value adjustments	(15,293)	(15,613)
Fair value adjustments - fair value option	(109,669)	(130,739)
Total reinsurance reserves recoverable	2,077,923	1,867,841	$ 2,217,033
Paid losses recoverable	208,524	161,822
Net	2,286,447	2,029,663
Reinsurance balances recoverable	1,551,190	1,290,072
Reinsurance balances recoverable - fair value option	735,257	739,591
Non-life Run-off
Effects of Reinsurance [Line Items]
Outstanding losses	1,007,758	901,772
IBNR	695,921	609,434
Fair value adjustments	(14,364)	(14,344)
Fair value adjustments - fair value option	(109,669)	(130,739)
Total reinsurance reserves recoverable	1,579,646	1,366,123	1,703,481	$ 1,377,485
Paid losses recoverable	170,633	138,265
Net	1,750,279	1,504,388
Reinsurance balances recoverable	1,015,022	764,797
Reinsurance balances recoverable - fair value option	735,257	739,591
Atrium
Effects of Reinsurance [Line Items]
Outstanding losses	11,242	18,891
IBNR	19,726	19,247
Fair value adjustments	714	630
Fair value adjustments - fair value option	0	0
Total reinsurance reserves recoverable	31,682	38,768	40,025	40,531
Paid losses recoverable	647	(256)
Net	32,329	38,512
Reinsurance balances recoverable	32,329	38,512
Reinsurance balances recoverable - fair value option	0	0
StarStone
Effects of Reinsurance [Line Items]
Outstanding losses	290,095	263,065
IBNR	178,143	201,784
Fair value adjustments	(1,643)	(1,899)
Fair value adjustments - fair value option	0	0
Total reinsurance reserves recoverable	466,595	462,950	$ 473,527	$ 452,017
Paid losses recoverable	37,244	23,813
Net	503,839	486,763
Reinsurance balances recoverable	503,839	486,763
Reinsurance balances recoverable - fair value option	$ 0	$ 0

Reinsurance Balances Recoverable on Paid and Unpaid Losses - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 2,286,447		$ 2,029,663
Increase (decrease) in reinsurance recoverable	256,706	$ 347,798
Non-Life Run-Off and StarStone Segment
Effects of Reinsurance [Line Items]
Increase (decrease) in reinsurance recoverable	$ 256,800

Reinsurance Balances Recoverable on Paid and Unpaid Losse - Top Ten Reinsurers (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019 USD ($) reinsurer	Dec. 31, 2018 USD ($) reinsurer
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 2,286,447	$ 2,029,663
Top ten reinsurers \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	1,524,371
Top 10 Total \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 1,285,067	$ 1,096,272
Number of external reinsurers \| reinsurer	8	7
Top Ten Reinsurers, Four Non-Rated Reinsurers \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 239,304	$ 316,238
Number of external reinsurers \| reinsurer	2	3
Reinsurance balances recoverable \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 2,286,447	$ 2,029,663
Concentration risk percentage	100.00%	100.00%
Reinsurance balances recoverable \| Top ten reinsurers \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 1,524,371	$ 1,412,510
Concentration risk percentage	66.70%	69.60%
Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 741,888	$ 596,312
Concentration risk percentage	32.40%	29.40%
Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 20,188	$ 20,841
Concentration risk percentage	0.90%	1.00%
Non-life Run-off
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 1,750,279	$ 1,504,388
Non-life Run-off \| Reinsurance balances recoverable \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	1,750,279	1,504,388
Non-life Run-off \| Reinsurance balances recoverable \| Top ten reinsurers \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	1,202,892	1,124,079
Non-life Run-off \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	532,030	364,098
Non-life Run-off \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	15,357	16,211
Atrium
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	32,329	38,512
Atrium \| Reinsurance balances recoverable \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	32,329	38,512
Atrium \| Reinsurance balances recoverable \| Top ten reinsurers \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	22,421	25,239
Atrium \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	8,149	12,091
Atrium \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	1,759	1,182
StarStone
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	503,839	486,763
StarStone \| Reinsurance balances recoverable \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	503,839	486,763
StarStone \| Reinsurance balances recoverable \| Top ten reinsurers \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	299,058	263,192
StarStone \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	201,709	220,123
StarStone \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	3,072	3,448
Equity Method Investee \| Hannover Ruck \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	297,129	279,723
Equity Method Investee \| Lloyds of London \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 392,205	$ 334,509

Reinsurance Balances Recoverable on Paid and Unpaid Losses - Summary of Provisions for Uncollectible Reinsurance Balances Recoverable by Rating of Reinsurer (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Effects of Reinsurance [Line Items]
Gross	$ 2,447,926	$ 2,186,395
Provisions for Bad Debt	161,479	156,732
Net	$ 2,286,447	$ 2,029,663
Provisions as a % of Gross	6.60%	7.20%
Reinsurers rated A- or above
Effects of Reinsurance [Line Items]
Gross	$ 1,883,418	$ 1,612,464
Provisions for Bad Debt	54,048	51,519
Net	$ 1,829,370	$ 1,560,945
Provisions as a % of Gross	2.90%	3.20%
Secured \| Reinsurers rated below A-
Effects of Reinsurance [Line Items]
Gross	$ 421,205	$ 430,852
Provisions for Bad Debt	0	0
Net	$ 421,205	$ 430,852
Provisions as a % of Gross	0.00%	0.00%
Unsecured \| Reinsurers rated below A-
Effects of Reinsurance [Line Items]
Gross	$ 143,303	$ 143,079
Provisions for Bad Debt	107,431	105,213
Net	$ 35,872	$ 37,866
Provisions as a % of Gross	75.00%	73.50%

Deferred Charge Assets - Reconciliation of Deferred Charge Assets (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning carrying value	$ 86,585,000	$ 80,192,000
Recorded during the period	20,632,000	0
Amortization	(7,063,000)	(5,081,000)
Ending carrying value	100,154,000	$ 75,111,000
Impairment loss of deferred charge assets	$ 0

Losses and Loss Adjustment Expenses - Balance Sheet Summary by Segment (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	$ 5,542,208	$ 5,168,900
IBNR	4,684,984	4,468,991
Fair value adjustments	(205,344)	(214,518)
Fair value adjustments - fair value option	(300,774)	(374,752)
ULAE	374,948	360,883
Total	10,096,022	9,409,504	$ 8,986,070	$ 7,398,088
Loss and loss adjustment expenses	7,248,229	6,535,449
Loss and loss adjustment expenses, at fair value	2,847,793	2,874,055
Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Total	8,154,974	7,540,662	7,517,511	5,949,472
Atrium
Liability for Claims and Claims Adjustment Expense [Line Items]
Total	229,380	241,284	240,795	240,873
StarStone
Liability for Claims and Claims Adjustment Expense [Line Items]
Total	1,690,686	1,608,697	$ 1,227,764	$ 1,207,743
Operating Segments \| Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	4,624,209	4,271,769
IBNR	3,694,932	3,527,767
Fair value adjustments	(209,631)	(217,527)
Fair value adjustments - fair value option	(300,774)	(374,752)
ULAE	346,238	333,405
Total	8,154,974	7,540,662
Loss and loss adjustment expenses	5,307,181	4,666,607
Loss and loss adjustment expenses, at fair value	2,847,793	2,874,055
Operating Segments \| Atrium
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	86,986	94,885
IBNR	135,411	140,521
Fair value adjustments	4,691	3,476
Fair value adjustments - fair value option	0	0
ULAE	2,292	2,402
Total	229,380	241,284
Loss and loss adjustment expenses	229,380	241,284
Loss and loss adjustment expenses, at fair value	0	0
Operating Segments \| StarStone
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	824,366	796,194
IBNR	840,306	787,894
Fair value adjustments	(404)	(467)
Fair value adjustments - fair value option	0	0
ULAE	26,418	25,076
Total	1,690,686	1,608,697
Loss and loss adjustment expenses	1,690,686	1,608,697
Loss and loss adjustment expenses, at fair value	0	0
Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	6,647	6,052
IBNR	14,335	12,809
Fair value adjustments	0	0
Fair value adjustments - fair value option	0	0
ULAE	0	0
Total	20,982	18,861
Loss and loss adjustment expenses	20,982	18,861
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 (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as at beginning of period	$ 9,409,504	$ 7,398,088
Less: reinsurance reserves recoverable	1,867,841
Less: deferred charges on retroactive reinsurance	86,585	80,192
Net balance as at beginning of period	7,455,078	5,447,863
Net incurred losses and LAE:
Current period	217,266	95,154
Prior periods	95,138	(75,620)
Total net incurred losses and LAE	312,404	19,534
Net paid losses:
Current period	(28,029)	(8,103)
Prior periods	(461,605)	(350,646)
Net losses paid	(489,634)	(358,749)
Effect of exchange rate movement	19,679	57,727
Assumed business	620,418	1,527,551
Net balance as of March 31	7,917,945	6,693,926
Plus: reinsurance reserves recoverable	2,077,923	2,217,033
Plus: deferred charges on retroactive reinsurance	100,154	75,111
Balance as of March 31	10,096,022	8,986,070
Non-Life Run-off Segment, Atrium Segment, and Starstone Segment
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less: reinsurance reserves recoverable	1,867,841	1,870,033
Non-life Run-off
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as at beginning of period	7,540,662	5,949,472
Less: reinsurance reserves recoverable	1,366,123	1,377,485
Less: deferred charges on retroactive reinsurance	86,585	80,192
Net balance as at beginning of period	6,087,954	4,491,795
Net incurred losses and LAE:
Current period	49,071	346
Prior periods	46,111	(73,324)
Total net incurred losses and LAE	95,182	(72,978)
Net paid losses:
Current period	(18,014)	(1)
Prior periods	(331,055)	(252,583)
Net losses paid	(349,069)	(252,584)
Effect of exchange rate movement	20,689	55,403
Assumed business	620,418	1,517,283
Net balance as of March 31	6,475,174	5,738,919
Plus: reinsurance reserves recoverable	1,579,646	1,703,481
Plus: deferred charges on retroactive reinsurance	100,154	75,111
Balance as of March 31	8,154,974	7,517,511
Atrium
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as at beginning of period	241,284	240,873
Less: reinsurance reserves recoverable	38,768	40,531
Net balance as at beginning of period	202,516	200,342
Net incurred losses and LAE:
Current period	18,237	17,306
Prior periods	(1,023)	(134)
Total net incurred losses and LAE	17,214	17,172
Net paid losses:
Current period	(7,893)	(7,154)
Prior periods	(14,420)	(10,376)
Net losses paid	(22,313)	(17,530)
Effect of exchange rate movement	281	786
Net balance as of March 31	197,698	200,770
Plus: reinsurance reserves recoverable	31,682	40,025
Balance as of March 31	229,380	240,795
StarStone
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as at beginning of period	1,608,697	1,207,743
Less: reinsurance reserves recoverable	462,950	452,017
Net balance as at beginning of period	1,145,747	755,726
Net incurred losses and LAE:
Current period	144,950	77,502
Prior periods	50,102	(2,162)
Total net incurred losses and LAE	195,052	75,340
Net paid losses:
Current period	(1,792)	(948)
Prior periods	(113,625)	(87,687)
Net losses paid	(115,417)	(88,635)
Effect of exchange rate movement	(1,291)	1,538
Assumed business	0	10,268
Net balance as of March 31	1,224,091	754,237
Plus: reinsurance reserves recoverable	466,595	473,527
Balance as of March 31	$ 1,690,686	$ 1,227,764

Losses and Loss Adjustment Expenses - Net (Reduction) Increase in Ultimate Losses and Loss Adjustment Expense Liabilities (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Prior Period
Net losses paid	$ 461,605	$ 350,646
Net incurred losses and LAE, prior period	95,138	(75,620)
Current Period
Net losses paid	28,029	8,103
Net incurred losses and LAE, current period	217,266	95,154
Total
Net losses paid	489,634	358,749
Net change in case and LAE reserves	(75,463)	(124,071)
Net change in IBNR reserves	(160,762)	(164,691)
Increase (reduction) in estimates of net ultimate losses	253,409	69,987
Increase (reduction) in provisions for unallocated LAE	(13,827)	(14,760)
Amortization of deferred charges	7,064	5,081
Amortization of fair value adjustments	9,717	(533)
Changes in fair value - fair value option	56,041	(40,241)
Total net incurred losses and LAE	312,404	19,534
Non-life Run-off
Prior Period
Net losses paid	331,055	252,583
Net change in case and LAE reserves	(97,573)	(123,492)
Net change in IBNR reserves	(243,815)	(154,450)
Increase (reduction) in estimates of net ultimate losses	(10,333)	(25,359)
Increase (reduction) in provisions for unallocated LAE	(15,440)	(14,952)
Amortization of deferred charge assets	7,064	5,081
Amortization of fair value adjustments	8,779	2,147
Changes in fair value - fair value option	56,041	(40,241)
Net incurred losses and LAE, prior period	46,111	(73,324)
Current Period
Net losses paid	18,014	1
Net change in case and LAE reserves	19,872	6
Net change in IBNR reserves	10,920	339
Increase (reduction) in estimates of net ultimate losses	48,806	346
Increase (reduction) in provisions for unallocated LAE	265	0
Amortization of deferred charge assets	0	0
Amortization of fair value adjustments	0	0
Changes in fair value - fair value option	0	0
Net incurred losses and LAE, current period	49,071	346
Total
Net losses paid	349,069	252,584
Net change in case and LAE reserves	(77,701)	(123,486)
Net change in IBNR reserves	(232,895)	(154,111)
Increase (reduction) in estimates of net ultimate losses	38,473	(25,013)
Increase (reduction) in provisions for unallocated LAE	(15,175)	(14,952)
Amortization of deferred charges	7,064	5,081
Amortization of fair value adjustments	8,779	2,147
Changes in fair value - fair value option	56,041	(40,241)
Total net incurred losses and LAE	95,182	(72,978)
Atrium
Prior Period
Net losses paid	14,420	10,376
Net change in case and LAE reserves	(6,342)	(2,384)
Net change in IBNR reserves	(10,232)	(5,587)
Increase (reduction) in estimates of net ultimate losses	(2,154)	2,405
Amortization of fair value adjustments	1,131	(2,539)
Net incurred losses and LAE, prior period	(1,023)	(134)
Current Period
Net losses paid	7,893	7,154
Net change in case and LAE reserves	5,929	6,274
Net change in IBNR reserves	4,415	3,878
Increase (reduction) in estimates of net ultimate losses	18,237	17,306
Amortization of fair value adjustments	0	0
Net incurred losses and LAE, current period	18,237	17,306
Total
Net losses paid	22,313	17,530
Net change in case and LAE reserves	(413)	3,890
Net change in IBNR reserves	(5,817)	(1,709)
Increase (reduction) in estimates of net ultimate losses	16,083	19,711
Amortization of fair value adjustments	1,131	(2,539)
Total net incurred losses and LAE	17,214	17,172
StarStone
Prior Period
Net losses paid	113,625	87,687
Net change in case and LAE reserves	(8,824)	(14,217)
Net change in IBNR reserves	(52,834)	(73,390)
Increase (reduction) in estimates of net ultimate losses	51,967	80
Increase (reduction) in provisions for unallocated LAE	(1,672)	(2,101)
Amortization of fair value adjustments	(193)	(141)
Net incurred losses and LAE, prior period	50,102	(2,162)
Current Period
Net losses paid	1,792	948
Net change in case and LAE reserves	10,880	9,742
Net change in IBNR reserves	129,258	64,519
Increase (reduction) in estimates of net ultimate losses	141,930	75,209
Increase (reduction) in provisions for unallocated LAE	3,020	2,293
Amortization of fair value adjustments	0	0
Net incurred losses and LAE, current period	144,950	77,502
Total
Net losses paid	115,417	88,635
Net change in case and LAE reserves	2,056	(4,475)
Net change in IBNR reserves	76,424	(8,871)
Increase (reduction) in estimates of net ultimate losses	193,897	75,289
Increase (reduction) in provisions for unallocated LAE	1,348	192
Amortization of fair value adjustments	(193)	(141)
Total net incurred losses and LAE	195,052	75,340
Operating Segments \| Non-life Run-off
Total
Net losses paid	349,069	252,584
Net change in case and LAE reserves	(77,701)	(123,486)
Net change in IBNR reserves	(232,895)	(154,111)
Increase (reduction) in estimates of net ultimate losses	38,473	(25,013)
Increase (reduction) in provisions for unallocated LAE	(15,175)	(14,952)
Amortization of deferred charges	7,064	5,081
Amortization of fair value adjustments	8,779	2,147
Changes in fair value - fair value option	56,041	(40,241)
Total net incurred losses and LAE	95,182	(72,978)
Operating Segments \| Atrium
Total
Net losses paid	22,313	17,530
Net change in case and LAE reserves	(413)	3,890
Net change in IBNR reserves	(5,817)	(1,709)
Increase (reduction) in estimates of net ultimate losses	16,083	19,711
Increase (reduction) in provisions for unallocated LAE	0	0
Amortization of deferred charges	0	0
Amortization of fair value adjustments	1,131	(2,539)
Changes in fair value - fair value option	0	0
Total net incurred losses and LAE	17,214	17,172
Operating Segments \| StarStone
Total
Net losses paid	115,417	88,635
Net change in case and LAE reserves	2,056	(4,475)
Net change in IBNR reserves	76,424	(8,871)
Increase (reduction) in estimates of net ultimate losses	193,897	75,289
Increase (reduction) in provisions for unallocated LAE	1,348	192
Amortization of deferred charges	0	0
Amortization of fair value adjustments	(193)	(141)
Changes in fair value - fair value option	0	0
Total net incurred losses and LAE	195,052	75,340
Other
Total
Net losses paid	2,835
Net change in case and LAE reserves	595
Net change in IBNR reserves	1,526
Increase (reduction) in estimates of net ultimate losses	4,956
Increase (reduction) in provisions for unallocated LAE	0
Amortization of deferred charges	0
Amortization of fair value adjustments	0
Changes in fair value - fair value option	0
Total net incurred losses and LAE	$ 4,956	$ 0

Losses and Loss Adjustment Expenses - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Effects of Reinsurance [Line Items]
Net incurred losses and LAE	$ 312,404	$ 19,534
Net incurred losses and LAE, current period	217,266	95,154
Prior periods	95,138	(75,620)
Net losses paid	461,605	350,646
Non-life Run-off
Effects of Reinsurance [Line Items]
Net incurred losses and LAE	95,182	(72,978)
Net incurred losses and LAE, current period	49,071	346
Prior periods	46,111	(73,324)
Increase (reduction) in estimates of net ultimate losses	(10,333)	(25,359)
Increase (reduction) in provisions for unallocated LAE	(15,440)	(14,952)
Decrease in fair value - fair value option, Prior Period	(56,041)	40,241
Amortization of fair value adjustments	8,779	2,147
Net losses paid	331,055	252,583
Amortization of deferred charge assets	7,064	5,081
Non-life Run-off \| Workers Compensation Business
Effects of Reinsurance [Line Items]
Net change in case and IBNR reserves	(341,400)	(277,900)
StarStone
Effects of Reinsurance [Line Items]
Net incurred losses and LAE	195,052	75,340
Net incurred losses and LAE, current period	144,950	77,502
Prior periods	50,102	(2,162)
Increase (reduction) in estimates of net ultimate losses	51,967	80
Increase (reduction) in provisions for unallocated LAE	(1,672)	(2,101)
Amortization of fair value adjustments	(193)	(141)
Net losses paid	$ 113,625	$ 87,687

Fair Value Measurements - Investments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reinsurance balances recoverable
Beginning fair value	$ 321,973	$ 176,723
Purchases		14,065
Sales	(3,589)	(12,566)
Total realized and unrealized gains	3,436	(251)
Transfer into Level 3 from Level 2	6,612	20,156
Transfer out of Level 3 into Level 2	(45,503)	(13,903)
Ending fair value	282,929	184,224
Corporate
Reinsurance balances recoverable
Beginning fair value	37,386	67,178
Purchases		10,832
Sales	(2,660)	(7,037)
Total realized and unrealized gains	257	195
Transfer into Level 3 from Level 2	387	15,259
Transfer out of Level 3 into Level 2	(32,198)	(400)
Ending fair value	3,172	86,027
Residential mortgage-backed
Reinsurance balances recoverable
Beginning fair value		3,080
Purchases		0
Sales		(1,148)
Total realized and unrealized gains		(25)
Transfer into Level 3 from Level 2		0
Transfer out of Level 3 into Level 2		0
Ending fair value		1,907
Commercial mortgage-backed
Reinsurance balances recoverable
Beginning fair value	7,389	21,494
Purchases		1,803
Sales	(608)	(577)
Total realized and unrealized gains	62	83
Transfer into Level 3 from Level 2	0	4,897
Transfer out of Level 3 into Level 2	(6,843)	(10,066)
Ending fair value	0	17,634
Asset-backed
Reinsurance balances recoverable
Beginning fair value	9,121	27,892
Purchases		1,300
Sales	(321)	(3,804)
Total realized and unrealized gains	737	46
Transfer into Level 3 from Level 2	6,225	0
Transfer out of Level 3 into Level 2	(6,462)	(3,437)
Ending fair value	9,300	21,997
Equities
Reinsurance balances recoverable
Beginning fair value	228,710
Sales	0
Total realized and unrealized gains	0
Transfer into Level 3 from Level 2	0
Transfer out of Level 3 into Level 2	0
Ending fair value	228,710
Other Investments
Reinsurance balances recoverable
Beginning fair value	39,367	57,079
Purchases		130
Sales	0	0
Total realized and unrealized gains	2,380	(550)
Transfer into Level 3 from Level 2	0	0
Transfer out of Level 3 into Level 2	0	0
Ending fair value	$ 41,747	$ 56,659

Fair Value Measurements - Insurance Contracts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reinsurance balances recoverable
Beginning fair value	$ 321,973	$ 176,723
Assumed business		14,065
Incurred losses and LAE:
Change in fair value	(3,436)	251
Ending fair value	282,929	184,224
Net
Beginning fair value	2,134,464	1,252,445
Assumed business	0	1,517,281
Incurred losses and LAE:
Reduction in estimates of ultimate losses	(3,668)	167
Reduction in unallocated LAE	(4,341)	(5,882)
Change in fair value	56,041	(40,241)
Total incurred losses and LAE	48,032	(45,956)
Paid losses	(88,618)	(140,226)
Effect of exchange rate movements	18,658	47,173
Ending fair value	2,112,536	2,630,717
Losses and LAE liabilities
Liability for losses and LAE
Beginning fair value	2,874,055	1,794,669
Assumed business	0	1,890,061
Incurred losses and LAE:
Reduction in estimates of ultimate losses	(7,154)	(1,309)
Reduction in unallocated LAE	(4,341)	(5,882)
Change in fair value	77,461	(57,155)
Total incurred losses and LAE	65,966	(64,346)
Paid losses	(115,860)	(158,372)
Effect of exchange rate movements	23,632	57,441
Ending fair value	2,847,793	3,519,453
Reinsurance balances recoverable
Reinsurance balances recoverable
Beginning fair value	739,591	542,224
Assumed business	0	372,780
Incurred losses and LAE:
Reduction in estimates of ultimate losses	(3,486)	(1,476)
Reduction in unallocated LAE	0	0
Change in fair value	21,420	(16,914)
Total incurred losses and LAE	17,934	(18,390)
Paid losses	(27,242)	(18,146)
Effect of exchange rate movements	4,974	10,268
Ending fair value	735,257	888,736
Duration
Incurred losses and LAE:
Change in fair value	9,047	5,540
Corporate bond yield
Incurred losses and LAE:
Change in fair value	$ 46,994	$ (45,781)

Fair Value Measurements - Observable and Unobservable Inputs (Details) - Internal Model - Recurring	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Losses and LAE liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Weighted average cost of capital	8.50%	8.50%
Duration	7 years 4 months 24 days	7 years 3 months 29 days
Reinsurance balances recoverable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk cost of capital	5.10%	5.00%
Duration	8 years 3 days	7 years 11 months 22 days
Measurement Input, Entity Credit Risk \| Losses and LAE liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit spread for non-performance risk	0.20%	0.20%

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 10, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, amortized cost	$ 1,103,790	$ 861,539
Senior Notes Due 2022 \| Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate	4.50%		4.50%
Debt, amortized cost	$ 348,180	$ 348,054
Debt, fair value	$ 356,300

Policy Benefits for Life Contracts (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Insurance [Abstract]
Policy benefits for life contracts	$ 100,682	$ 105,080

Premiums Written and Earned - Schedule of Net Premiums Written and Earned (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Effects of Reinsurance [Line Items]
Gross, premiums written	$ 285,345	$ 362,848
Ceded, premiums written	(62,578)	(139,701)
Net, premiums written	222,767	223,147
Gross, premiums earned	402,289	288,777
Ceded premium earned	(67,002)	(118,558)
Net, premiums earned	335,287	170,219
Operating Segments \| Non-life Run-off
Effects of Reinsurance [Line Items]
Gross, premiums written	(20,877)	7,380
Ceded, premiums written	1,699	(7,280)
Net, premiums written	(19,178)	100
Gross, premiums earned	83,966	13,110
Ceded premium earned	(7,292)	(5,932)
Net, premiums earned	76,674	7,178
Operating Segments \| Atrium
Effects of Reinsurance [Line Items]
Gross, premiums written	53,985	49,442
Ceded, premiums written	(7,486)	(7,948)
Net, premiums written	46,499	41,494
Gross, premiums earned	43,386	39,674
Ceded premium earned	(4,633)	(4,451)
Net, premiums earned	38,753	35,223
Operating Segments \| StarStone
Effects of Reinsurance [Line Items]
Gross, premiums written	251,373	304,989
Ceded, premiums written	(56,772)	(124,426)
Net, premiums written	194,601	180,563
Gross, premiums earned	268,264	234,943
Ceded premium earned	(55,002)	(108,117)
Net, premiums earned	213,262	126,826
Other
Effects of Reinsurance [Line Items]
Gross, premiums written	864	1,037
Ceded, premiums written	(19)	(47)
Net, premiums written	845	990
Gross, premiums earned	6,673	1,050
Ceded premium earned	(75)	(58)
Net, premiums earned	$ 6,598	$ 992

Premiums Written and Earned - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Insurance [Abstract]
Gross, premiums written	$ 285,345	$ 362,848
Decrease in gross premiums written	$ 77,500

Goodwill and Intangible Assets - Schedule of Goodwill and Intangible Assets (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Goodwill [Roll Forward]
Goodwill, Beginning balance	$ 114,807
Goodwill, Ending balance	114,807
Finite-lived Intangible Assets [Roll Forward]
Intangible assets with a definite life - other, Beginning balance	16,887
Intangible assets with a definite life - other, Amortization	(565)
Intangible assets with a definite life - other, Ending balance	16,322
Indefinite-lived Intangible Assets [Roll Forward]
Intangible assets with an indefinite life, Beginning balance	87,031
Intangible assets with an indefinite life, Ending balance	87,031
Intangible Assets [Roll Forward]
Intangible assets, Beginning Balance	103,918
Intangible assets with a definite life - other, Amortization	(565)
Intangible assets, Ending Balance	103,353
Goodwill and Intangible Assets [Roll Forward]
Goodwill and intangible assets, Beginning Balance	218,725
Goodwill and intangible assets, Ending balance	$ 218,160

Goodwill and Intangible Assets - Intangible Asset Amortization (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 565	$ 1,266

Goodwill and Intangible Assets - Summary of Gross Carrying Value, Accumulated Amortization and Net Carrying Value of Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Intangible assets with a definite life:
Gross Carrying Value	$ 42,000	$ 42,000
Accumulated Amortization	(25,678)	(25,113)
Net Carrying Value	16,322	16,887
Indefinite-lived Intangible Assets [Line Items]
Intangible assets with an indefinite life, Carrying Value	87,031	87,031
Lloyd’s syndicate capacity
Indefinite-lived Intangible Assets [Line Items]
Intangible assets with an indefinite life, Carrying Value	37,031	37,031
Licenses
Indefinite-lived Intangible Assets [Line Items]
Intangible assets with an indefinite life, Carrying Value	19,900	19,900
Management contract
Indefinite-lived Intangible Assets [Line Items]
Intangible assets with an indefinite life, Carrying Value	30,100	30,100
Distribution channel
Intangible assets with a definite life:
Gross Carrying Value	20,000	20,000
Accumulated Amortization	(7,111)	(6,776)
Net Carrying Value	12,889	13,224
Technology
Intangible assets with a definite life:
Gross Carrying Value	15,000	15,000
Accumulated Amortization	(14,833)	(14,778)
Net Carrying Value	167	222
Brand
Intangible assets with a definite life:
Gross Carrying Value	7,000	7,000
Accumulated Amortization	(3,734)	(3,559)
Net Carrying Value	$ 3,266	$ 3,441

Debt Obligations - Amounts Outstanding and Accrued Interest (Detail) - USD ($) $ in Thousands			3 Months Ended
	Dec. 27, 2018	Sep. 16, 2014	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Debt Instrument [Line Items]
Debt, amortized cost			$ 1,103,790		$ 861,539
Interest expense on debt obligations			10,726	$ 7,439
Funds withheld balances and other			310	572
Total interest expense			$ 11,036	$ 8,011
Senior Notes \| Senior Notes Due 2022
Debt Instrument [Line Items]
Term			5 years
Debt, amortized cost			$ 348,180		348,054
Line of Credit \| EGL Revolving Credit Facility
Debt Instrument [Line Items]
Term		5 years	5 years
Debt, amortized cost			$ 257,000		15,000
Line of Credit \| 2018 EGL Term Loan Facility
Debt Instrument [Line Items]
Term	3 years		3 years
Debt, amortized cost			$ 498,610		$ 498,485

Debt Obligations - Additional Information (Detail) - USD ($)				1 Months Ended	3 Months Ended
	Dec. 27, 2018	Mar. 10, 2017	Sep. 16, 2014	May 08, 2019	Mar. 31, 2019	Mar. 31, 2018	Feb. 12, 2019	Dec. 31, 2018	Aug. 16, 2018	Feb. 08, 2018
Line of Credit Facility [Line Items]
Repayment of loans					$ 102,000,000	$ 132,938,000
Cash and investments					$ 642,100,000
Senior Notes \| Senior Notes Due 2022
Line of Credit Facility [Line Items]
Outstanding amount of debt		$ 350,000,000.0
Stated interest rate		4.50%			4.50%
Redemption price percentage		100.00%
Payments of debt issuance costs		$ 2,900,000
Unamortized costs					$ 1,800,000			$ 1,900,000
Term of debt					5 years
Line of Credit \| 2018 EGL Term Loan Facility
Line of Credit Facility [Line Items]
Payments of debt issuance costs	$ 1,500,000
Unamortized costs					$ 1,400,000			$ 1,500,000
Term of debt	3 years				3 years
Maximum borrowing capacity	$ 500,000,000.0
Optional increase in borrowing capacity	$ 150,000,000
Interest payment period	3 months
Line of Credit \| 2018 EGL Revolving Credit Facility
Line of Credit Facility [Line Items]
Term of debt			5 years		5 years
Maximum borrowing capacity					$ 600,000,000.0				$ 600,000,000.0
Optional increase in borrowing capacity									$ 400,000,000.0
Line of credit facility, remaining borrowing capacity					343,000,000.0
Line of Credit \| 2018 EGL Revolving Credit Facility \| Subsequent Event
Line of Credit Facility [Line Items]
Line of credit facility, remaining borrowing capacity				$ 385,000,000.0
Repayment of loans				$ 42,000,000.0
Letters of Credit \| Line of Credit \| FAL Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity					$ 368,000,000.0					$ 325,000,000.0
Optional increase in borrowing capacity							$ 400,000,000.0
Higher borrowing capacity option							$ 375,000,000.0

Noncontrolling Interests - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Noncontrolling Interest [Line Items]
Noncontrolling interest	$ 12,452	$ 12,056
Trident \| Subsidiaries
Noncontrolling Interest [Line Items]
Interest owned by an entity (percent)		39.30%
Dowling \| Subsidiaries
Noncontrolling Interest [Line Items]
Interest owned by an entity (percent)		1.70%
Trident \| Subsidiaries
Noncontrolling Interest [Line Items]
Interest owned by an entity (percent)	39.30%
Dowling \| Subsidiaries
Noncontrolling Interest [Line Items]
Interest owned by an entity (percent)	1.70%

Noncontrolling Interests - Carrying Amount of Equity Attributable to Noncontrolling Interest (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Increase (Decrease) in Redeemable Noncontrolling Interest [Roll Forward]
Balance at beginning of period	$ 458,543	$ 479,606
Capital contributions	0	55,377
Dividends paid	0	(3,852)
Net losses attributable to RNCI	(2,544)	(64,794)
Accumulated other comprehensive earnings (losses) attributable to RNCI	85	(240)
Change in redemption value of RNCI	262	(7,554)
Balance at end of period	$ 456,346	$ 458,543

Share Capital - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended
	May 05, 2019	Feb. 21, 2019	Mar. 31, 2019	Mar. 31, 2018
Class of Stock [Line Items]
Total dividends paid			$ 9,139	$ 0
Series D Preferred Stock
Class of Stock [Line Items]
Declared cash dividends (in dollars per share)		$ 437.50
Declared cash dividends (in dollars per depositary share)		$ 0.43750
Total dividends paid		$ 7,000
Series E Preferred Stock
Class of Stock [Line Items]
Declared cash dividends (in dollars per share)		$ 486.11
Declared cash dividends (in dollars per depositary share)		$ 0.48611
Total dividends paid		$ 2,139
Subsequent Event \| Series D Preferred Stock
Class of Stock [Line Items]
Declared cash dividends (in dollars per share)	$ 437.50
Declared cash dividends (in dollars per depositary share)	$ 0.43750
Total dividends paid	$ 0
Subsequent Event \| Series E Preferred Stock
Class of Stock [Line Items]
Declared cash dividends (in dollars per share)	$ 437.50
Declared cash dividends (in dollars per depositary share)	$ 0.43750
Total dividends paid	$ 0

Earnings Per Share - Comparison of Basic and Diluted Earnings per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net earnings (losses) attributable to Enstar Group Limited	$ 358,751	$ (41,210)
Denominator:
Weighted-average ordinary shares outstanding — basic (in shares)	21,463,499	19,409,021
Effect of dilutive securities:
Share-based compensation plans (in shares)	122,980	115,630
Warrants (in shares)	59,383	77,861
Weighted-average ordinary shares outstanding — diluted (in shares)	21,645,862	19,602,512
Earnings (Loss) per ordinary share attributable to Enstar Group Limited:
Basic (in dollars per share)	$ 16.71	$ (2.12)
Diluted (in dollars per share)	$ 16.57	$ (2.12)

Share-Based Compensation and Pensions (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 5,200	$ 8,102
Pension plans:
Defined contribution plans	2,854	2,638
Defined benefit plan	175	151
Total pension costs	3,029	2,789
Restricted Stock and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	1,843	2,349
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	1,325	2,475
Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	56	1,241
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	103	83
Long Term Incentive Plans \| Time-Based Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	1,046	1,108
Restricted Stock Units (RSUs) \| Director \| Deferred Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation and ordinary share plan for non-employee directors	$ 827	$ 846

Income Taxation - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Effective tax rate	1.30%	(0.40%)
Statutory rate	0.00%
Unrecognized tax benefits	$ 0		$ 0

Related Party Transactions - Stone Point Capital LLC (Details) $ in Thousands		3 Months Ended
	Dec. 26, 2018 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Jul. 31, 2012 shares	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Nov. 06, 2013 general_partners
Related Party Transaction [Line Items]
Redeemable noncontrolling interest		$ 456,346	$ 458,543		$ 458,543	$ 479,606
Related Party, Consolidated Balance Sheet [Abstract]
Other investments, at fair value		2,324,345			1,957,757
Investments in registered investment companies affiliated with entities owned by Trident or Stone Point		400,420			367,125
Related Party, Consolidated Statement of Earnings [Abstract]
Net realized and unrealized gains (losses)		460,791	(143,030)
CLO equities
Related Party, Consolidated Balance Sheet [Abstract]
Other investments, at fair value		41,434			39,052
Affiliated Entity
Related Party, Consolidated Balance Sheet [Abstract]
Total investments		1,022,808			676,147
Trident \| Affiliated Entity
Related Party Transaction [Line Items]
Related party transaction, shares acquired \| shares				1,635,986
Number of newly elected board of directors \| general_partners							1
Number of general partners \| general_partners							4
Redeemable noncontrolling interest		437,322			439,428
Related Party, Consolidated Balance Sheet [Abstract]
Other investments, at fair value		611,262			422,771
Investments in registered investment companies affiliated with entities owned by Trident or Stone Point		27,882			32,302
Trident \| Affiliated Entity \| Fund Investments
Related Party, Consolidated Statement of Earnings [Abstract]
Net realized and unrealized gains (losses)		24,182	(1,526)
Trident \| Affiliated Entity \| Registered Investment Companies
Related Party, Consolidated Statement of Earnings [Abstract]
Net realized and unrealized gains (losses)		(4,420)	6,205
Interest income		680	1,082
Eagle Point Credit and PRIMA Capital Advisors \| Affiliated Entity
Related Party, Consolidated Balance Sheet [Abstract]
Separate account assets and investments		350,194			176,624
Eagle Point Credit and PRIMA Capital Advisors \| Affiliated Entity \| Management Fee
Related Party, Consolidated Statement of Earnings [Abstract]
Management fees		(87)	(227)
Sound Point Capital \| Affiliated Entity
Related Party, Consolidated Balance Sheet [Abstract]
Other investments, at fair value		19,889			29,922
Separate account assets and investments		115			1,079
Related Party, Consolidated Statement of Earnings [Abstract]
Net realized and unrealized gains (losses)		354	(529)
Sound Point Capital \| Affiliated Entity \| CLO equities
Related Party, Consolidated Balance Sheet [Abstract]
Other investments, at fair value		13,466			13,449
Related Party, Consolidated Statement of Earnings [Abstract]
Net realized and unrealized gains (losses)		17	(231)
Interest income		482	1,310
Sound Point Capital \| Affiliated Entity \| Management Fee
Related Party, Consolidated Statement of Earnings [Abstract]
Management fees		0	(81)
StonePoint And Affiliated Entities \| Affiliated Entity
Related Party, Consolidated Statement of Earnings [Abstract]
Total net earnings		$ 21,208	$ 6,003
Trident \| North Bay
Related Party Transaction [Line Items]
Payments to acquire investments	$ 53,100
Stone Point \| Affiliated Entity
Related Party Transaction [Line Items]
Ownership percentage		9.10%
North Bay Shareholders \| North Bay
Related Party Transaction [Line Items]
Payments to acquire investments	$ 135,000
Mitchell International \| Affiliated Entity
Related Party, Consolidated Balance Sheet [Abstract]
Other investments, at fair value					$ 25,000

Related Party Transactions - KaylaRe (Details) - USD ($) $ in Thousands			3 Months Ended
	May 14, 2018	Dec. 15, 2016	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	May 13, 2018	Dec. 31, 2016
Related Party Transaction [Line Items]
Ownership percentage			47.40%		47.40%
Related Party, Consolidated Statement of Earnings [Abstract]
Management fee income				$ 1,397
Ceded premium earned			$ (67,002)	(118,558)
Net incurred losses and LAE			312,404	19,534
Acquisition costs			93,788	30,108
Net earnings (loss)			$ 365,742	(40,428)
Kayla Re
Related Party Transaction [Line Items]
Initial capital raise		$ 620,000
KaylaRe transactions with Starstone
Related Party, Consolidated Statement of Earnings [Abstract]
Ceded premium earned				(52,651)
Net incurred losses and LAE				31,543
Acquisition costs				18,774
Kayla Re
Related Party Transaction [Line Items]
Ownership percentage						48.20%
Kayla Re
Related Party Transaction [Line Items]
Shares issued (in shares)	2,007,017
Ordinary Shares \| Kayla Re
Related Party Transaction [Line Items]
Shares issued (in shares)	1,501,778
Ordinary Shares \| Kayla Re \| Hillhouse
Related Party Transaction [Line Items]
Shares issued (in shares)	1,204,353
Ordinary Shares \| Kayla Re \| Trident
Related Party Transaction [Line Items]
Shares issued (in shares)	285,986
Non-voting convertible ordinary Series E Shares (issued and outstanding 2019 and 2018: 910,010) \| Kayla Re
Related Party Transaction [Line Items]
Shares issued (in shares)	505,239
Non-voting convertible ordinary Series E Shares (issued and outstanding 2019 and 2018: 910,010) \| Kayla Re \| Hillhouse
Related Party Transaction [Line Items]
Shares issued (in shares)	505,239
Non-voting convertible ordinary Series E Shares (issued and outstanding 2019 and 2018: 910,010) \| Kayla Re \| Minority Shareholder
Related Party Transaction [Line Items]
Shares issued (in shares)	11,439
Starstone \| Kayla Re
Related Party Transaction [Line Items]
Percentage of business reinsured			35.00%
Fitzwilliam \| Subsidiaries \| Kayla Re
Related Party Transaction [Line Items]
Ceded reinsurance receivables							$ 177,200
Affiliated Entity \| Kayla Re
Related Party, Consolidated Statement of Earnings [Abstract]
Net earnings (loss)				$ (937)

Related Party Transactions - Hillhouse (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Other investments	$ 2,324,345		$ 1,957,757
Ownership percentage	47.40%		47.40%
Additional subscriptions	$ 225,961	$ 275,862
Hillhouse Affiliates \| Affiliated Entity
Related Party Transaction [Line Items]
Ownership percentage	9.70%
Economic interest percentage	17.00%
Hillhouse
Related Party Transaction [Line Items]
Other investments	$ 992,712		$ 845,066
Hillhouse \| Affiliated Entity
Related Party Transaction [Line Items]
Other investments	100,561		35,641
Fees incurred	31,900
Hillhouse \| Kayla Re \| Affiliated Entity
Related Party Transaction [Line Items]
Other investments	212,155		75,192
InRe Fund \| Hillhouse \| Affiliated Entity
Related Party Transaction [Line Items]
Other investments	792,980		678,420
Other Funds \| Hillhouse \| Affiliated Entity
Related Party Transaction [Line Items]
Other investments	$ 199,732		$ 166,646
Fixed Income Securities \| Hillhouse InRe Fund, L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Other investments, percentage of funds	37.00%
North American Equities \| Hillhouse InRe Fund, L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Other investments, percentage of funds	24.00%
International Equities \| Hillhouse InRe Fund, L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Other investments, percentage of funds	67.00%
Financing, Derivatives And Other Items \| Hillhouse InRe Fund, L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Other investments, percentage of funds	(28.00%)

Related Party Transactions - Monument (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Oct. 31, 2016	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Contributed amount of common and preferred shares		$ 9,762	$ 0
Ownership percentage		47.40%		47.40%
Carrying value of previously held equity method investment prior to the close of the transaction		$ 221,023		$ 204,507
Monument
Related Party Transaction [Line Items]
Contributed amount of common and preferred shares	$ 26,600
Ownership percentage		26.60%		26.60%
Carrying value of previously held equity method investment prior to the close of the transaction		$ 47,746		$ 42,193

Related Party Transactions - Clear Spring (Details) - USD ($) $ in Thousands		3 Months Ended
	Jan. 01, 2017	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Capitalized amount of investment	$ 56,000
Ownership percentage		47.40%		47.40%
Carrying value of previously held equity method investment prior to the close of the transaction		$ 221,023		$ 204,507
Balances under StarStone ceding quota share:
Reinsurance balances recoverable		2,286,447		2,029,663
Losses and LAE
Losses and LAE		10,096,022	$ 8,986,070	9,409,504	$ 7,398,088
Unearned reinsurance premiums		951,042		842,618
Funds held		919,738		321,267
Transactions under StarStone ceding quota share:
Ceded premium earned		(67,002)	(118,558)
Acquisition costs		(93,788)	(30,108)
Net earnings (loss)		365,742	(40,428)
Transactions under assuming quota share:
Net incurred losses and LAE		$ 312,404	19,534
Clear Spring \| Equity Method Investee
Related Party Transaction [Line Items]
Ownership percentage		20.00%
Balances under StarStone ceding quota share:
Reinsurance balances recoverable		$ 26,415		23,718
Prepaid insurance premiums		8,527		13,821
Ceded payable		11,830		14,153
Ceded acquisition costs		2,039		3,233
Clear Spring \| Affiliated Entity
Transactions under StarStone ceding quota share:
Net earnings (loss)		(1,180)	238
Starstone \| Clear Spring
Related Party Transaction [Line Items]
Carrying value of previously held equity method investment prior to the close of the transaction		10,070		10,070
Percentage of business reinsured	33.30%
Starstone \| Clear Spring \| Affiliated Entity
Transactions under StarStone ceding quota share:
Ceded premium earned		(5,485)	(7,003)
Ceded incurred losses and LAE		3,859	5,562
Acquisition costs		(54)	(1,782)
Starstone \| Cavello Bay
Related Party Transaction [Line Items]
Percentage of business reinsured	25.00%
Cavello Bay \| Clear Spring
Losses and LAE
Losses and LAE		6,301		5,778
Unearned reinsurance premiums		2,132		3,455
Funds held		9,833		$ 10,242
Cavello Bay \| Clear Spring \| Affiliated Entity
Transactions under StarStone ceding quota share:
Acquisition costs		(14)	(464)
Transactions under assuming quota share:
Premium earned		1,371	1,751
Net incurred losses and LAE		$ (965)	$ (1,390)

Related Party Transactions - AmTrust (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		12 Months Ended
	Nov. 30, 2018	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Purchase amount of equity interest		$ 9,762	$ 0
Management fee income			1,397
Net Investment Earnings [Abstract]
Net investment income		78,696	$ 66,319
Affiliated Entity
Related Party Transaction [Line Items]
Investment in related party		1,022,808		$ 676,147
AmTrust Financial Services, Inc.
Related Party Transaction [Line Items]
Investment in related party		200,000		200,000
AmTrust Financial Services, Inc. \| Affiliated Entity
Related Party Transaction [Line Items]
Ownership percentage	45.00%
Trident Pine \| Evergreen Parent L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Capital units ownership percentage	21.80%
Evergreen Parent L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Purchase amount of equity interest	$ 200,000
Capital units ownership percentage	7.50%
Management fee income				$ 3,500
AmTrust Financial Services, Inc. \| Affiliated Entity
Related Party Transaction [Line Items]
Investment in related party		200,000
Net Investment Earnings [Abstract]
Net investment income		$ 1,821

Related Party Transactions - Citco (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Jun. 30, 2018	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Indirect investment acquired		$ 225,961	$ 275,862
Other investments		$ 2,324,345		$ 1,957,757
Trident \| Citco \| Affiliated Entity
Related Party Transaction [Line Items]
Indirect investment acquired	$ 50,000
Ownership percentage		3.40%
Citco
Related Party Transaction [Line Items]
Other investments		$ 50,917		$ 50,812

Related Party Transactions - Enhanced Re Header (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Mar. 31, 2019
Related Party Transaction [Line Items]
Management fee income	$ 1,397
Equity method investments		$ 204,507	$ 221,023
Ownership percentage		47.40%	47.40%
Enstar \| Enhanzed Re
Related Party Transaction [Line Items]
Equity method investments			$ 94,800
Ownership percentage			47.40%
Uncalled amount of investment			$ 128,000
Allianz \| Enhanzed Re
Related Party Transaction [Line Items]
Ownership percentage			24.90%
Hillhouse \| Enhanzed Re
Related Party Transaction [Line Items]
Ownership percentage			27.70%
Enhanzed Re
Related Party Transaction [Line Items]
Equity method investments		$ 94,800	$ 91,883
Ownership percentage		47.40%	47.40%
Enhanzed Re \| Affiliated Entity
Related Party Transaction [Line Items]
Management fee income		$ 100
Equity method investments			$ 470,000

Commitments and Contingencies - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Feb. 12, 2019	Dec. 31, 2018
Guarantor Obligations [Line Items]
Funds held by reinsured companies	$ 919,738		$ 321,267
Lease optional renewal period	5 years
Lease optional termination period	1 year
Limited Parental Guarantee
Guarantor Obligations [Line Items]
Parental guarantees	$ 669,600		$ 614,500
US
Guarantor Obligations [Line Items]
Concentration of credit risk, counterparty credit exposure	711,800
Reinsurance Recoverables \| Reinsurer Concentration Risk
Guarantor Obligations [Line Items]
Funds held by reinsured companies	1,101,900
Line of Credit \| FAL Facility \| Letters of Credit
Guarantor Obligations [Line Items]
Higher borrowing capacity option		$ 375,000
Optional increase in borrowing capacity		$ 400,000
Letters of credit issued	368,000
Private equities and private equity funds
Guarantor Obligations [Line Items]
Commitments, unfunded	210,800
Equity Method Investments
Guarantor Obligations [Line Items]
Commitments, unfunded	$ 152,300
Maximum
Guarantor Obligations [Line Items]
Weighted-average remaining lease term	38 years
Minimum
Guarantor Obligations [Line Items]
Weighted-average remaining lease term	1 year
AmTrust RITC
Guarantor Obligations [Line Items]
Funds held by reinsured companies	$ 601,900

Commitments and Contingencies - Asbestos and Environmental Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Other liabilities:
TOTAL LIABILITIES	$ 13,321,741	$ 12,183,738
Other assets:
TOTAL ASSETS	18,058,251	16,556,270
Dana properties
Other liabilities:
Estimated future expenses	17,717	19,843
Fair value adjustments	(84,350)	(84,650)
TOTAL LIABILITIES	197,511	203,320
Other assets:
Insurance recoveries related to direct asbestos and environmental liabilities	178,100	183,676
Fair value adjustments	(47,669)	(47,868)
TOTAL ASSETS	130,431	135,808
Net liabilities relating to direct asbestos and environmental exposures	(67,080)	(67,512)
Direct Asbestos Liabilities \| Dana properties
Other liabilities:
Liability for asbestos and environmental claims	262,098	265,975
Direct Environmental Liabilities \| Dana properties
Other liabilities:
Liability for asbestos and environmental claims	$ 2,046	$ 2,152

Commitments and Contingencies - Leases - Lease Cost (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 3,487
Sublease income	(131)
Total lease cost	$ 3,356

Commitments and Contingencies - Leases - Cash Flow Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Operating cash flow information:
Cash paid for amounts included in the measurement of lease liabilities	$ 3,024
Non-cash activity:
Right-of-use assets obtained in exchange for lease obligations	$ 51,609

Commitments and Contingencies - Leases - Balance Sheet Information (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Right-of-use assets	$ 48,870
Current lease liabilities	9,063
Non-current lease liabilities	$ 40,270

Commitments and Contingencies - Leases - Lease Terms (Details)	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Weighted-average remaining lease term	6 years 7 months 6 days
Weighted-average discount rate	6.20%

Commitments and Contingencies - Leases - Operating Lease Liabilities (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Operating Lease Liabilities, Payments Due [Abstract]
2019	$ 8,223
2020	12,469
2021	9,022
2022	7,454
2023	6,605
2024 and beyond	18,010
Total lease payments	61,783
Less: Imputed interest	(12,450)
Present value of lease liabilities	$ 49,333

Segment Information - Additional Information (Detail)	3 Months Ended
Segment Information - Additional Information (Detail)	Mar. 31, 2019 Segment
Segment Reporting [Abstract]
Number of reportable segments	3

Segment Information - Summary of Operations by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Gross premiums written	$ 285,345	$ 362,848
Net premiums written	222,767	223,147
Net premiums earned	335,287	170,219
Net incurred losses and LAE	(312,404)	(19,534)
Life and Annuity Policy Benefits	(96)	46
Acquisition costs	(93,788)	(30,108)
Operating expenses	(83,019)	(77,137)
Underwriting income	(154,020)	43,486
Net investment income	78,696	66,319
Net realized and unrealized gains (losses)	460,791	(143,030)
Fees and commission income	6,681	8,331
Other income (expense)	5,812	1,943
Corporate expenses	(29,055)	(18,123)
Interest income (expense)	(11,036)	(8,011)
Net foreign exchange losses	3,850	(5,868)
EARNINGS (LOSS) BEFORE INCOME TAXES	361,719	(54,953)
INCOME (TAXES) BENEFIT	(4,749)	(172)
Earnings from equity method investments	8,772	14,697
NET EARNINGS (LOSS)	365,742	(40,428)
Net loss (earnings) attributable to noncontrolling interest	2,148	(782)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED	367,890	(41,210)
Dividends on preferred shares	(9,139)	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	358,751	(41,210)
Non-life Run-off
Segment Reporting Information [Line Items]
Net incurred losses and LAE	(95,182)	72,978
Atrium
Segment Reporting Information [Line Items]
Net incurred losses and LAE	$ (17,214)	$ (17,172)
Underwriting Ratios [Abstract]
Loss ratio	44.40%	48.80%
Acquisition expense ratio	35.50%	34.30%
Operating expense ratio	7.80%	11.80%
Combined ratio	87.70%	94.90%
StarStone
Segment Reporting Information [Line Items]
Net incurred losses and LAE	$ (195,052)	$ (75,340)
Underwriting Ratios [Abstract]
Loss ratio	91.50%	59.40%
Acquisition expense ratio	24.20%	13.00%
Operating expense ratio	16.90%	27.20%
Combined ratio	132.60%	99.60%
Operating Segments \| Non-life Run-off
Segment Reporting Information [Line Items]
Gross premiums written	$ (20,877)	$ 7,380
Net premiums written	(19,178)	100
Net premiums earned	76,674	7,178
Net incurred losses and LAE	(95,182)	72,978
Life and Annuity Policy Benefits	0	0
Acquisition costs	(28,155)	(1,470)
Operating expenses	(43,992)	(38,403)
Underwriting income	(90,655)	40,283
Net investment income	66,728	51,651
Net realized and unrealized gains (losses)	436,186	(126,296)
Fees and commission income	4,832	4,898
Other income (expense)	5,504	2,558
Corporate expenses	(16,570)	(8,633)
Interest income (expense)	(12,116)	(8,530)
Net foreign exchange losses	3,618	(7,177)
EARNINGS (LOSS) BEFORE INCOME TAXES	397,527	(51,246)
INCOME (TAXES) BENEFIT	(2,720)	1,117
Earnings from equity method investments	8,584	14,697
NET EARNINGS (LOSS)	403,391	(35,432)
Net loss (earnings) attributable to noncontrolling interest	(2,646)	(1,429)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED	400,745
Dividends on preferred shares	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	400,745	(36,861)
Operating Segments \| Atrium
Segment Reporting Information [Line Items]
Gross premiums written	53,985	49,442
Net premiums written	46,499	41,494
Net premiums earned	38,753	35,223
Net incurred losses and LAE	(17,214)	(17,172)
Life and Annuity Policy Benefits	0	0
Acquisition costs	(13,742)	(12,065)
Operating expenses	(3,033)	(4,177)
Underwriting income	4,764	1,809
Net investment income	1,711	1,185
Net realized and unrealized gains (losses)	2,913	(1,403)
Fees and commission income	1,849	3,433
Other income (expense)	36	64
Corporate expenses	(3,788)	(475)
Interest income (expense)	0	0
Net foreign exchange losses	825	(953)
EARNINGS (LOSS) BEFORE INCOME TAXES	8,310	3,660
INCOME (TAXES) BENEFIT	(685)	(280)
Earnings from equity method investments	0	0
NET EARNINGS (LOSS)	7,625	3,380
Net loss (earnings) attributable to noncontrolling interest	(3,128)	(1,411)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED	4,497
Dividends on preferred shares	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	4,497	1,969
Operating Segments \| StarStone
Segment Reporting Information [Line Items]
Gross premiums written	251,373	304,989
Net premiums written	194,601	180,563
Net premiums earned	213,262	126,826
Net incurred losses and LAE	(195,052)	(75,340)
Life and Annuity Policy Benefits	0	0
Acquisition costs	(51,659)	(16,425)
Operating expenses	(35,994)	(34,557)
Underwriting income	(69,443)	504
Net investment income	11,942	7,701
Net realized and unrealized gains (losses)	20,658	(12,958)
Fees and commission income	0	0
Other income (expense)	60	51
Corporate expenses	0	0
Interest income (expense)	(475)	(541)
Net foreign exchange losses	(594)	1,095
EARNINGS (LOSS) BEFORE INCOME TAXES	(37,852)	(4,148)
INCOME (TAXES) BENEFIT	(1,259)	(998)
Earnings from equity method investments	188	0
NET EARNINGS (LOSS)	(38,923)	(5,146)
Net loss (earnings) attributable to noncontrolling interest	7,922	2,058
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED	(31,001)
Dividends on preferred shares	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	(31,001)	(3,088)
Other
Segment Reporting Information [Line Items]
Gross premiums written	864	1,037
Net premiums written	845	990
Net premiums earned	6,598	992
Net incurred losses and LAE	(4,956)	0
Life and Annuity Policy Benefits	(96)	46
Acquisition costs	(232)	(148)
Operating expenses	0	0
Underwriting income	1,314	890
Net investment income	(1,685)	5,782
Net realized and unrealized gains (losses)	1,034	(2,373)
Fees and commission income	0	0
Other income (expense)	212	(730)
Corporate expenses	(8,697)	(9,015)
Interest income (expense)	1,555	1,060
Net foreign exchange losses	1	1,167
EARNINGS (LOSS) BEFORE INCOME TAXES	(6,266)	(3,219)
INCOME (TAXES) BENEFIT	(85)	(11)
Earnings from equity method investments	0	0
NET EARNINGS (LOSS)	(6,351)	(3,230)
Net loss (earnings) attributable to noncontrolling interest	0	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED	(6,351)
Dividends on preferred shares	(9,139)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$ (15,490)	$ (3,230)

Segment Information - Summary of Company's Assets by Segment (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 18,058,251	$ 16,556,270
Operating Segments \| Non-life Run-off
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	14,661,681	13,362,749
Operating Segments \| Atrium
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	588,126	591,722
Operating Segments \| StarStone
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	3,464,379	3,416,132
Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ (655,935)	$ (814,333)

Label	Element	Value
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 0
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (1,573,000)

Investments - Credit Ratings (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 8,690,362
Fair Value	8,739,303
Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 309,305
Marketable Securities \| Portfolio Concentration Risk \| Trading Securities and Available for Sale Securities
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	100.00%
Marketable Securities \| Credit Rating Concentration Risk \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments		3.50%
AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 2,123,794
AAA Rated \| Marketable Securities \| Credit Rating Concentration Risk \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	24.30%
AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,306,092
AA Rated \| Marketable Securities \| Credit Rating Concentration Risk \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments		14.90%
A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 2,866,548
A Rated \| Marketable Securities \| Credit Rating Concentration Risk \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	32.90%
BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 2,100,723
BBB Rated \| Marketable Securities \| Credit Rating Concentration Risk \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	24.00%
Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 32,841
Not Rated \| Marketable Securities \| Credit Rating Concentration Risk
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments		0.40%
U.S. government and agency
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	415,689
Fair Value	417,306
U.S. government and agency \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 0
U.S. government and agency \| Marketable Securities \| Portfolio Concentration Risk \| Trading Securities and Available for Sale Securities
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	4.80%
U.S. government and agency \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 417,243
U.S. government and agency \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	63
U.S. government and agency \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
U.S. government and agency \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
U.S. government and agency \| Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
U.K. government
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	261,213
Fair Value	278,443
U.K. government \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 0
U.K. government \| Marketable Securities \| Portfolio Concentration Risk \| Trading Securities and Available for Sale Securities
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	3.20%
U.K. government \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 644
U.K. government \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	277,799
U.K. government \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
U.K. government \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
U.K. government \| Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
Other government
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	769,300
Fair Value	769,976
Other government \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 35,765
Other government \| Marketable Securities \| Portfolio Concentration Risk \| Trading Securities and Available for Sale Securities
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	8.80%
Other government \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 308,413
Other government \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	198,228
Other government \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	55,991
Other government \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	171,579
Other government \| Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
Corporate
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	5,079,783
Fair Value	5,104,015
Corporate \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 197,543
Corporate \| Marketable Securities \| Portfolio Concentration Risk \| Trading Securities and Available for Sale Securities
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	58.40%
Corporate \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 132,282
Corporate \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	506,434
Corporate \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	2,517,323
Corporate \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	1,737,171
Corporate \| Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	13,262
Municipal
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	156,818
Fair Value	160,066
Municipal \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 0
Municipal \| Marketable Securities \| Portfolio Concentration Risk \| Trading Securities and Available for Sale Securities
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	1.80%
Municipal \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 12,284
Municipal \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	81,059
Municipal \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	49,814
Municipal \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	16,909
Municipal \| Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
Residential mortgage-backed
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	424,195
Fair Value	429,005
Residential mortgage-backed \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 51,372
Residential mortgage-backed \| Marketable Securities \| Portfolio Concentration Risk \| Trading Securities and Available for Sale Securities
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	4.90%
Residential mortgage-backed \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 309,100
Residential mortgage-backed \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	55,819
Residential mortgage-backed \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	2,054
Residential mortgage-backed \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	3,119
Residential mortgage-backed \| Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	7,541
Commercial mortgage-backed
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	884,640
Fair Value	884,124
Commercial mortgage-backed \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 6,514
Commercial mortgage-backed \| Marketable Securities \| Portfolio Concentration Risk \| Trading Securities and Available for Sale Securities
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	10.10%
Commercial mortgage-backed \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 641,337
Commercial mortgage-backed \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	87,319
Commercial mortgage-backed \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	77,117
Commercial mortgage-backed \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	61,139
Commercial mortgage-backed \| Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	10,698
Asset-backed
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	698,724
Fair Value	696,368
Asset-backed \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 18,111
Asset-backed \| Marketable Securities \| Portfolio Concentration Risk \| Trading Securities and Available for Sale Securities
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	8.00%
Asset-backed \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 302,491
Asset-backed \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	99,371
Asset-backed \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	164,249
Asset-backed \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	110,806
Asset-backed \| Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,340

Fair Value Measurements - Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Investments:
Equities, at fair value	$ 400,420	$ 367,125
Total investments	8,739,303	8,697,892
Reinsurance recoverable	(109,669)	(130,739)
Other Assets:
Losses and LAE	2,847,793	2,874,055
U.S. government and agency
Investments:
Total investments	417,306	510,245
U.K. government
Investments:
Total investments	278,443	300,631
Corporate
Investments:
Total investments	5,104,015	4,839,840
Municipal
Investments:
Total investments	160,066	130,265
Residential mortgage-backed
Investments:
Total investments	429,005	773,557
Commercial mortgage-backed
Investments:
Total investments	884,124	713,063
Asset-backed
Investments:
Total investments	696,368	636,481
Recurring
Investments:
Equities, at fair value	400,420	367,125
Total investments	11,552,664	11,037,554
Cash and cash equivalents	264,319	264,985
Other Assets:
Losses and LAE	2,847,793	2,874,055
Recurring \| Fixed Maturities
Investments:
Fixed maturity investments	8,739,303	8,697,892
Recurring \| Other investments
Investments:
Other investments	2,324,345	1,957,757
Recurring \| Reinsurance recoverable
Investments:
Reinsurance recoverable	735,257	739,591
Recurring \| Derivative instruments, assets
Other Assets:
Derivative Instruments	5,278	6,701
Recurring \| Derivative instruments, liabilities
Other Liabilities:
Derivative Instruments	64	983
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Investments:
Equities, at fair value	140,398	102,102
Total investments	215,313	102,102
Cash and cash equivalents	157,543	243,839
Other Assets:
Losses and LAE	0	0
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Other investments
Investments:
Other investments	0	0
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Reinsurance recoverable
Investments:
Reinsurance recoverable	0	0
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Derivative instruments, assets
Other Assets:
Derivative Instruments	0	0
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Derivative instruments, liabilities
Other Liabilities:
Derivative Instruments	0	0
Recurring \| Significant Other Observable Inputs (Level 2)
Investments:
Equities, at fair value	31,312	36,313
Total investments	9,350,042	9,086,971
Cash and cash equivalents	106,776	21,146
Other Assets:
Losses and LAE	0	0
Recurring \| Significant Other Observable Inputs (Level 2) \| Fixed Maturities
Investments:
Fixed maturity investments	8,726,831	8,643,996
Recurring \| Significant Other Observable Inputs (Level 2) \| Other investments
Investments:
Other investments	578,218	391,882
Recurring \| Significant Other Observable Inputs (Level 2) \| Reinsurance recoverable
Investments:
Reinsurance recoverable	0	0
Recurring \| Significant Other Observable Inputs (Level 2) \| Derivative instruments, assets
Other Assets:
Derivative Instruments	5,278	6,701
Recurring \| Significant Other Observable Inputs (Level 2) \| Derivative instruments, liabilities
Other Liabilities:
Derivative Instruments	64	983
Recurring \| Significant Unobservable Inputs (Level 3)
Investments:
Equities, at fair value	228,710	228,710
Total investments	282,929	321,973
Cash and cash equivalents	0	0
Other Assets:
Losses and LAE	2,847,793	2,874,055
Recurring \| Significant Unobservable Inputs (Level 3) \| Fixed Maturities
Investments:
Fixed maturity investments	12,472	53,896
Recurring \| Significant Unobservable Inputs (Level 3) \| Other investments
Investments:
Other investments	41,747	39,367
Recurring \| Significant Unobservable Inputs (Level 3) \| Reinsurance recoverable
Investments:
Reinsurance recoverable	735,257	739,591
Recurring \| Significant Unobservable Inputs (Level 3) \| Derivative instruments, assets
Other Assets:
Derivative Instruments	0	0
Recurring \| Significant Unobservable Inputs (Level 3) \| Derivative instruments, liabilities
Other Liabilities:
Derivative Instruments	0	0
Recurring \| Fair Value Based on NAV as Practical Expedient
Investments:
Total investments	1,704,380	1,526,508
Cash and cash equivalents	0	0
Recurring \| Fair Value Based on NAV as Practical Expedient \| Other investments
Investments:
Other investments	1,704,380	1,526,508
Recurring \| U.S. government and agency \| Fixed Maturities
Investments:
Fixed maturity investments	417,306	510,245
Recurring \| U.S. government and agency \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| U.S. government and agency \| Significant Other Observable Inputs (Level 2) \| Fixed Maturities
Investments:
Fixed maturity investments	417,306	510,245
Recurring \| U.S. government and agency \| Significant Unobservable Inputs (Level 3) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| U.K. government \| Fixed Maturities
Investments:
Fixed maturity investments	278,443	300,631
Recurring \| U.K. government \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| U.K. government \| Significant Other Observable Inputs (Level 2) \| Fixed Maturities
Investments:
Fixed maturity investments	278,443	300,631
Recurring \| U.K. government \| Significant Unobservable Inputs (Level 3) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| Other government \| Fixed Maturities
Investments:
Fixed maturity investments	769,976	793,810
Recurring \| Other government \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| Other government \| Significant Other Observable Inputs (Level 2) \| Fixed Maturities
Investments:
Fixed maturity investments	769,976	793,810
Recurring \| Other government \| Significant Unobservable Inputs (Level 3) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| Corporate \| Fixed Maturities
Investments:
Fixed maturity investments	5,104,015	4,839,840
Recurring \| Corporate \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| Corporate \| Significant Other Observable Inputs (Level 2) \| Fixed Maturities
Investments:
Fixed maturity investments	5,100,843	4,802,454
Recurring \| Corporate \| Significant Unobservable Inputs (Level 3) \| Fixed Maturities
Investments:
Fixed maturity investments	3,172	37,386
Recurring \| Municipal \| Fixed Maturities
Investments:
Fixed maturity investments	160,066	130,265
Recurring \| Municipal \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| Municipal \| Significant Other Observable Inputs (Level 2) \| Fixed Maturities
Investments:
Fixed maturity investments	160,066	130,265
Recurring \| Municipal \| Significant Unobservable Inputs (Level 3) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| Residential mortgage-backed \| Fixed Maturities
Investments:
Fixed maturity investments	429,005	773,557
Recurring \| Residential mortgage-backed \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| Residential mortgage-backed \| Significant Other Observable Inputs (Level 2) \| Fixed Maturities
Investments:
Fixed maturity investments	429,005	773,557
Recurring \| Residential mortgage-backed \| Significant Unobservable Inputs (Level 3) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| Commercial mortgage-backed \| Fixed Maturities
Investments:
Fixed maturity investments	884,124	713,063
Recurring \| Commercial mortgage-backed \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| Commercial mortgage-backed \| Significant Other Observable Inputs (Level 2) \| Fixed Maturities
Investments:
Fixed maturity investments	884,124	705,674
Recurring \| Commercial mortgage-backed \| Significant Unobservable Inputs (Level 3) \| Fixed Maturities
Investments:
Fixed maturity investments	0	7,389
Recurring \| Asset-backed \| Fixed Maturities
Investments:
Fixed maturity investments	696,368	636,481
Recurring \| Asset-backed \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| Asset-backed \| Significant Other Observable Inputs (Level 2) \| Fixed Maturities
Investments:
Fixed maturity investments	687,068	627,360
Recurring \| Asset-backed \| Significant Unobservable Inputs (Level 3) \| Fixed Maturities
Investments:
Fixed maturity investments	9,300	9,121
Recurring \| Funds held - directly managed \| Fixed Maturities
Investments:
Fixed maturity investments	88,596	14,780
Recurring \| Funds held - directly managed \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fixed Maturities
Investments:
Fixed maturity investments	74,915	0
Recurring \| Funds held - directly managed \| Significant Other Observable Inputs (Level 2) \| Fixed Maturities
Investments:
Fixed maturity investments	13,681	14,780
Recurring \| Funds held - directly managed \| Significant Unobservable Inputs (Level 3) \| Fixed Maturities
Investments:
Fixed maturity investments	0	0
Recurring \| Publicly traded equity investments
Investments:
Equities, at fair value	171,710	138,415
Recurring \| Publicly traded equity investments \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Investments:
Equities, at fair value	140,398	102,102
Recurring \| Publicly traded equity investments \| Significant Other Observable Inputs (Level 2)
Investments:
Equities, at fair value	31,312	36,313
Recurring \| Publicly traded equity investments \| Significant Unobservable Inputs (Level 3)
Investments:
Equities, at fair value	0	0
Recurring \| Private equities and private equity funds
Investments:
Equities, at fair value	228,710	228,710
Recurring \| Private equities and private equity funds \| Other investments
Investments:
Other investments	235,538	248,628
Recurring \| Private equities and private equity funds \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Investments:
Equities, at fair value	0	0
Recurring \| Private equities and private equity funds \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Other investments
Investments:
Other investments	0	0
Recurring \| Private equities and private equity funds \| Significant Other Observable Inputs (Level 2)
Investments:
Equities, at fair value		0
Recurring \| Private equities and private equity funds \| Significant Other Observable Inputs (Level 2) \| Other investments
Investments:
Other investments	0	0
Recurring \| Private equities and private equity funds \| Significant Unobservable Inputs (Level 3)
Investments:
Equities, at fair value	228,710	228,710
Recurring \| Private equities and private equity funds \| Significant Unobservable Inputs (Level 3) \| Other investments
Investments:
Other investments	0	0
Recurring \| Private equities and private equity funds \| Fair Value Based on NAV as Practical Expedient \| Other investments
Investments:
Other investments	235,538	248,628
Recurring \| Hedge funds \| Other investments
Investments:
Other investments	979,270	852,584
Recurring \| Hedge funds \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Other investments
Investments:
Other investments	0	0
Recurring \| Hedge funds \| Significant Other Observable Inputs (Level 2) \| Other investments
Investments:
Other investments	0	0
Recurring \| Hedge funds \| Significant Unobservable Inputs (Level 3) \| Other investments
Investments:
Other investments	0	0
Recurring \| Hedge funds \| Fair Value Based on NAV as Practical Expedient \| Other investments
Investments:
Other investments	979,270	852,584
Recurring \| Fixed income funds \| Other investments
Investments:
Other investments	587,093	403,858
Recurring \| Fixed income funds \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Other investments
Investments:
Other investments	0	0
Recurring \| Fixed income funds \| Significant Other Observable Inputs (Level 2) \| Other investments
Investments:
Other investments	469,643	290,864
Recurring \| Fixed income funds \| Significant Unobservable Inputs (Level 3) \| Other investments
Investments:
Other investments	0	0
Recurring \| Fixed income funds \| Fair Value Based on NAV as Practical Expedient \| Other investments
Investments:
Other investments	117,450	112,994
Recurring \| Equity funds \| Other investments
Investments:
Other investments	374,249	333,681
Recurring \| Equity funds \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Other investments
Investments:
Other investments	0	0
Recurring \| Equity funds \| Significant Other Observable Inputs (Level 2) \| Other investments
Investments:
Other investments	108,337	100,440
Recurring \| Equity funds \| Significant Unobservable Inputs (Level 3) \| Other investments
Investments:
Other investments	0	0
Recurring \| Equity funds \| Fair Value Based on NAV as Practical Expedient \| Other investments
Investments:
Other investments	265,912	233,241
Recurring \| CLO equities \| Other investments
Investments:
Other investments	41,434	39,052
Recurring \| CLO equities \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Other investments
Investments:
Other investments	0	0
Recurring \| CLO equities \| Significant Other Observable Inputs (Level 2) \| Other investments
Investments:
Other investments	0	0
Recurring \| CLO equities \| Significant Unobservable Inputs (Level 3) \| Other investments
Investments:
Other investments	41,434	39,052
Recurring \| CLO equities \| Fair Value Based on NAV as Practical Expedient \| Other investments
Investments:
Other investments	0	0
Recurring \| CLO equity fund \| Other investments
Investments:
Other investments	40,348	37,260
Recurring \| CLO equity fund \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Other investments
Investments:
Other investments	0	0
Recurring \| CLO equity fund \| Significant Other Observable Inputs (Level 2) \| Other investments
Investments:
Other investments	0	0
Recurring \| CLO equity fund \| Significant Unobservable Inputs (Level 3) \| Other investments
Investments:
Other investments	0	0
Recurring \| CLO equity fund \| Fair Value Based on NAV as Practical Expedient \| Other investments
Investments:
Other investments	40,348	37,260
Recurring \| Private credit funds \| Other investments
Investments:
Other investments	53,258	33,381
Recurring \| Private credit funds \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Other investments
Investments:
Other investments	0	0
Recurring \| Private credit funds \| Significant Other Observable Inputs (Level 2) \| Other investments
Investments:
Other investments	0	0
Recurring \| Private credit funds \| Significant Unobservable Inputs (Level 3) \| Other investments
Investments:
Other investments	0	0
Recurring \| Private credit funds \| Fair Value Based on NAV as Practical Expedient \| Other investments
Investments:
Other investments	53,258	33,381
Recurring \| Others \| Other investments
Investments:
Other investments	13,155	9,313
Recurring \| Others \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Other investments
Investments:
Other investments	0	0
Recurring \| Others \| Significant Other Observable Inputs (Level 2) \| Other investments
Investments:
Other investments	238	578
Recurring \| Others \| Significant Unobservable Inputs (Level 3) \| Other investments
Investments:
Other investments	313	315
Recurring \| Others \| Fair Value Based on NAV as Practical Expedient \| Other investments
Investments:
Other investments	$ 12,604	$ 8,420