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Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2018	Jul. 30, 2018
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
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Voting Ordinary Shares
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		17,947,289
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	Jun. 30, 2018	Dec. 31, 2017
ASSETS
Trading, at fair value	$ 6,688,325
Fixed maturities, available-for-sale, at fair value (amortized cost: 2018 — $168,565; 2017 — $208,097)	169,321	$ 210,285
Equities, trading, at fair value	130,404	106,603
Other investments, at fair value	1,768,333	913,392
Other investments, at cost	0	125,621
Total investments	8,756,383	7,232,185
Cash and cash equivalents	819,709	955,150
Restricted cash and cash equivalents	363,884	257,686
Funds held - directly managed	1,229,896	1,179,940
Premiums receivable	573,773	425,702
Deferred tax assets	13,230	13,001
Prepaid reinsurance premiums	196,052	245,101
Reinsurance balances recoverable	1,157,438	1,478,806
Reinsurance balances recoverable, at fair value	837,373	542,224
Funds held by reinsured companies	259,432	175,383
Deferred acquisition costs	128,781	64,984
Goodwill and intangible assets	219,865	180,589
Other assets	647,396	831,320
Assets held for sale	0	24,351
TOTAL ASSETS	15,203,212	13,606,422
LIABILITIES
Losses and loss adjustment expenses	5,387,021	5,603,419
Losses and loss adjustment expenses, at fair value	3,221,366	1,794,669
Policy benefits for life and annuity contracts	108,963	117,207
Unearned premiums	754,046	583,197
Insurance and reinsurance balances payable	354,100	236,697
Deferred tax liabilities	14,983	15,262
Debt obligations	439,610	646,689
Other liabilities	524,882	972,457
Liabilities held for sale	0	11,271
TOTAL LIABILITIES	10,804,971	9,980,868
COMMITMENTS AND CONTINGENCIES
REDEEMABLE NONCONTROLLING INTEREST	471,093	479,606
SHAREHOLDERS’ EQUITY
Treasury shares, at cost	(421,559)	(421,559)
Additional paid-in capital	1,808,063	1,395,067
Accumulated other comprehensive income	10,604	10,468
Retained earnings	2,098,484	2,132,912
Total Enstar Group Limited Shareholders’ Equity	3,917,421	3,136,684
Noncontrolling interest	9,727	9,264
TOTAL SHAREHOLDERS’ EQUITY	3,927,148	3,145,948
TOTAL LIABILITIES, REDEEMABLE NONCONTROLLING INTEREST AND SHAREHOLDERS’ EQUITY	15,203,212	13,606,422
Voting Ordinary shares (issued and outstanding 2018: 17,929,590; 2017: 16,402,279)
SHAREHOLDERS’ EQUITY
Ordinary shares	17,930	16,402
Non-voting convertible ordinary Series E Shares (issued and outstanding 2018: 910,010 and 2017: 404,771)
SHAREHOLDERS’ EQUITY
Ordinary shares	2,600	2,600
Preferred Shares:
SHAREHOLDERS’ EQUITY
Ordinary shares	910	405
Series C Preferred Shares (issued and held in treasury 2018 and 2017: 388,571)
SHAREHOLDERS’ EQUITY
Preferred Shares	389	389
Series D Preferred Shares (issued and outstanding 2018: 16,000)
SHAREHOLDERS’ EQUITY
Preferred Shares	400,000	0
Short-term Investments
ASSETS
Trading, at fair value	259,396	180,211
Fixed maturity investments
ASSETS
Trading, at fair value	6,428,929	5,696,073
Fixed maturities, available-for-sale, at fair value (amortized cost: 2018 — $168,565; 2017 — $208,097)	$ 169,321	$ 210,285

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Short-term investments, available-for-sale, at fair value, amortized cost	$ 168,565	$ 208,097
Ordinary shares, par value (in dollars per share)	$ 1	$ 1
Ordinary shares issued (in shares)	21,439,272	19,406,722
Ordinary shares outstanding (in shares)	21,439,272	19,406,722
Treasury shares at cost (in shares)	388,571	388,571
Voting Ordinary Shares
Ordinary shares issued (in shares)	17,929,590	16,402,279
Ordinary shares outstanding (in shares)	17,929,590	16,402,279
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	404,771
Ordinary shares outstanding (in shares)	910,010	404,771
Series C Preferred Shares
Preferred shares issued (in shares)	388,571	388,571
Series D Preferred Stock
Preferred shares issued (in shares)	16,000	0
Preferred shares outstanding (in shares)	16,000	0
Fixed maturity investments
Short-term investments, available-for-sale, at fair value, amortized cost	$ 168,565	$ 208,097

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
INCOME
Net premiums earned	$ 228,812	$ 155,571	$ 399,031	$ 304,469
Net investment income	66,469	49,417	132,788	98,156
Net realized and unrealized gains (losses)	(54,418)	51,877	(197,448)	110,396
Other income	6,294	10,856	22,934	23,054
Total income	255,509	286,388	373,988	566,656
EXPENSES
Net incurred losses and loss adjustment expenses	92,819	9,620	112,353	87,512
Life and annuity policy benefits	(160)	4,289	(206)	3,988
Acquisition costs	53,334	30,355	83,442	51,176
General and administrative expenses	102,612	106,490	197,872	208,958
Interest expense	8,922	7,573	16,933	14,441
Net foreign exchange gains (losses)	(5,519)	7,122	349	10,837
Loss on sale of subsidiary	0	9,609	0	9,609
Total expenses	252,008	175,058	410,743	386,521
EARNINGS (LOSS) BEFORE INCOME TAXES	3,501	111,330	(36,755)	180,135
INCOME TAXES	(3,646)	(4,731)	(3,818)	(1,802)
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	(145)	106,599	(40,573)	178,333
NET LOSS FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES	0	(4,871)	0	(4,500)
NET EARNINGS (LOSS)	(145)	101,728	(40,573)	173,833
Less: Net (earnings) losses attributable to noncontrolling interest	8,389	(11,542)	7,607	(28,967)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$ 8,244	$ 90,186	$ (32,966)	$ 144,866
Basic:
Net earnings (loss) from continuing operations (in dollars per share)	$ 0.40	$ 4.90	$ (1.65)	$ 7.71
Net earnings from discontinued operations (in dollars per share)	0.00	(0.25)	0.00	(0.23)
Net earnings (loss) per ordinary share (in dollars per share)	0.40	4.65	(1.65)	7.48
Diluted:
Net earnings (loss) from continuing operations (in dollars per share)	0.40	4.87	(1.65)	7.66
Net earnings from discontinued operations (in dollars per share)	0.00	(0.25)	0.00	(0.23)
Net earnings (loss) per ordinary share (in dollars per share)	$ 0.40	$ 4.62	$ (1.65)	$ 7.43
Weighted average ordinary shares outstanding:
Basic (in shares)	20,462,788	19,387,650	19,938,815	19,381,225
Diluted (in shares)	20,671,232	19,511,429	20,140,367	19,506,077
Fees and commission income
INCOME
Fees and commission income	$ 8,352	$ 18,667	$ 16,683	$ 30,581

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
NET EARNINGS (LOSS)	$ (145)	$ 101,728	$ (40,573)	$ 173,833
Other comprehensive income, net of tax:
Unrealized holding gains (losses) on fixed income investments arising during the period	(1,351)	1,693	(1,697)	2,379
Reclassification adjustment for net realized gains (losses) included in net earnings	21	(102)	51	(251)
Unrealized gains (losses) arising during the period, net of reclassification adjustments	(1,330)	1,591	(1,646)	2,128
Change in currency translation adjustment	176	2,315	1,401	4,257
Total other comprehensive income (loss)	(1,154)	3,906	(245)	6,385
Comprehensive income (loss)	(1,299)	105,634	(40,818)	180,218
Comprehensive (income) loss attributable to noncontrolling interest	8,745	(12,333)	7,989	(30,415)
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED	$ 7,446	$ 93,301	$ (32,829)	$ 149,803

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Ordinary Shares Voting Ordinary Shares	Ordinary Shares Class C Converted to 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	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, 2016		$ 16,175		$ 2,792	$ 405		$ 0		$ 1,380,109	$ (23,549)	$ (18,993)		$ 88	$ 1,847,550	$ 8,520
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of shares		19			0		0		66
Conversion of shares			$ 192	(192)
Issuance costs of preferred shares									0
Amortization of share-based compensation									6,157
Change in other comprehensive income (loss)	$ 6,385										4,253		685
Net earnings (losses)														144,866	898
Accretion of redeemable noncontrolling interests to redemption value														(1,015)
Contribution of capital															0
Balance, end of period at Jun. 30, 2017		16,386		2,600	405	$ 389	0	$ (421,559)	1,386,332	(18,611)	(14,740)	$ (4,644)	773	1,996,283	9,418
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle														4,882
Balance, beginning of period at Dec. 31, 2017	3,145,948	16,402		2,600	405		0		1,395,067	10,468	11,171		2,440	2,132,912	9,264
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of shares		1,528			505		400,000		413,204
Conversion of shares			$ 0	0
Issuance costs of preferred shares									(10,518)
Amortization of share-based compensation									10,310
Change in other comprehensive income (loss)	(245)										1,410		(1,274)
Net earnings (losses)														(32,966)	414
Accretion of redeemable noncontrolling interests to redemption value														111
Contribution of capital															49
Balance, end of period at Jun. 30, 2018	$ 3,927,148	$ 17,930		$ 2,600	$ 910	$ 389	$ 400,000	$ (421,559)	$ 1,808,063	$ 10,604	$ 12,581	$ (3,143)	$ 1,166	2,098,484	$ 9,727
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle														$ (1,573)

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
OPERATING ACTIVITIES:
Net earnings (loss)	$ (40,573)	$ 173,833
Net loss from discontinued operations	0	4,500
Adjustments to reconcile net earnings (losses) to cash flows used in operating activities:
Realized losses (gains) on sale of investments	7,661	(74)
Unrealized losses (gains) on investments	143,817	(88,304)
Other non-cash items	10,626	5,352
Depreciation and other amortization	17,593	18,797
Net change in trading securities held on behalf of policyholders	0	25,597
Sales and maturities of trading securities	1,983,155	2,225,349
Purchases of trading securities	(2,834,926)	(3,616,862)
Net loss on sale of subsidiary	0	9,609
Changes in:
Reinsurance balances recoverable	(339,827)	(570,731)
Funds held by reinsured companies	(134,005)	(212,927)
Losses and loss adjustment expenses	1,209,709	1,646,721
Policy benefits for life and annuity contracts	(5,059)	64
Insurance and reinsurance balances payable	117,741	75,890
Unearned premiums	170,849	39,739
Other operating assets and liabilities	(419,311)	898
Net cash flows used in operating activities	(112,550)	(262,549)
INVESTING ACTIVITIES:
Acquisitions, net of cash acquired	(5,657)	0
Sales and maturities of available-for-sale securities	44,112	45,932
Purchase of available-for-sale securities	(9,226)	(162)
Purchase of other investments	(462,336)	(67,516)
Redemption of other investments	324,633	152,650
Other investing activities	(7,841)	(9,708)
Net cash flows provided by (used in) investing activities	(105,001)	121,196
FINANCING ACTIVITIES:
Issuance of preferred shares, net of issuance costs	389,482	0
Contribution by noncontrolling interest	49	0
Dividends paid to noncontrolling interest	0	(27,458)
Receipt of loans	374,069	489,100
Repayment of loans	(578,062)	(528,500)
Net cash flows provided by (used in) financing activities	185,538	(66,858)
EFFECT OF EXCHANGE RATE CHANGES ON FOREIGN CURRENCY CASH AND CASH EQUIVALENTS	2,770	636
NET DECREASE IN CASH AND CASH EQUIVALENTS	(29,243)	(207,575)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	1,212,836	1,318,645
CHANGE IN CASH OF BUSINESSES HELD FOR SALE	0	(6,319)
CASH AND CASH EQUIVALENTS, END OF PERIOD	1,183,593	1,104,751
Supplemental Cash Flow Information:
Income taxes paid, net of refunds	13,928	6,538
Interest paid	16,247	8,959
Reconciliation to Consolidated Balance Sheets:
Cash, cash equivalents and restricted cash	$ 1,212,836	$ 1,318,645

Significant Accounting Policies

6 Months Ended

Jun. 30, 2018

Accounting Policies [Abstract]

SIGNIFICANT ACCOUNTING POLICIES

1. SIGNIFICANT ACCOUNTING POLICIES

Basis of Preparation and Consolidation

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, 2017. All significant inter-company transactions and balances have been eliminated. Results of operations for acquired subsidiaries are included from the date of acquisition. 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.

The preparation of these financial statements 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. 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. Our principal estimates include, but are not limited to:


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


•	liability for policy benefits for life contracts;


•	reinsurance balances recoverable;


•	gross and net premiums written and net premiums earned;


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


•	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 2018

Accounting Standards Update ("ASU") 2017-09, Stock Compensation - Scope of Modification Accounting

In May 2017, the Financial Accounting Standards Board ("FASB") issued ASU 2017-09, which amends the scope of modification accounting for share-based payment arrangements. The ASU provides guidance on the types of changes to the terms or conditions of share-based payment awards to which an entity would be required to apply modification accounting under Accounting Standards Codification ("ASC") 718 - Compensation - Stock Compensation. Specifically, an entity would not apply modification accounting if the fair value, vesting conditions, and classification of the awards are the same immediately before and after the modification. The adoption of this guidance did not have any impact on our consolidated financial statements and disclosures.

ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost

In March 2017, the FASB issued ASU 2017-07, which amends the requirements in ASC 715 - Compensation - Retirement Benefits, related to the income statement presentation of the components of net periodic benefit cost for an entity’s sponsored defined benefit pension and other postretirement plans. The ASU requires entities to (1) disaggregate the current-service-cost component from the other components of net benefit cost (the “other components”) and present it with other current compensation costs for related employees in the statement of earnings, and (2) present the other components elsewhere in the statement of earnings and outside of income from operations if such a subtotal is presented. The ASU also requires entities to disclose the captions within the statement of earnings that contain the other components if they are not presented on appropriately described separate lines. In addition, only the service-cost component of the net benefit cost is eligible for capitalization, which is a change from prior practice, under which entities capitalize the aggregate net benefit cost when applicable. The adoption of this guidance did not have any impact on our consolidated financial statements and disclosures.

ASU 2017-05, Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets

In February 2017, the FASB issued ASU 2017-05, which clarifies the scope of the Board’s guidance on nonfinancial asset derecognition (ASC 610-20) as well as the accounting for partial sales of nonfinancial assets. The ASU conforms the derecognition on nonfinancial assets with the model for transactions in the new revenue standard (ASC 606, as amended). The ASU clarifies that ASC 610-20 applies to the derecognition of all nonfinancial assets and in-substance nonfinancial assets. The ASU also requires an entity to derecognize the nonfinancial asset or in-substance nonfinancial asset in a partial sale transaction when (1) the entity ceases to have a controlling financial interest in a subsidiary pursuant to ASC 810, and (2) control of the asset is transferred in accordance with ASC 606. The adoption of this guidance did not have any impact on our consolidated financial statements and disclosures.

ASU 2016-16, Intra-Entity Transfers of Assets Other Than Inventory

In October 2016, the FASB issued ASU 2016-16, which requires immediate recognition of the tax consequences of many intercompany asset transfers other than inventory. The adoption of this guidance did not have a material impact on our consolidated financial statements and disclosures.

ASU 2016-15, Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments

In August 2016, the FASB issued ASU 2016-15, which amends the guidance on the classification of certain cash receipts and payments in the statement of cash flows. The adoption of this guidance did not have any impact on our consolidated financial statements and disclosures.

ASU 2016-01, Recognition and Measurement of Financial Instruments

In January 2016, the FASB issued ASU 2016-01, which amends the guidance on the classification and measurement of financial instruments. Although the ASU retains many of the current requirements, it significantly revises an entity’s accounting related to (1) the classification and measurement of investments in equity securities, and (2) the presentation of certain fair value changes for financial liabilities measured at fair value. The ASU also amends certain disclosure requirements associated with the fair value of financial instruments.

In February 2018, the FASB also issued ASU 2018-03, Technical Corrections and Improvements to Financial Instruments - Recognition and Measurement of Financial Assets and Financial Liabilities, which clarifies that entities should use a prospective transition approach only for equity securities they elect to measure using the new measurement alternative. The amendments also clarify that an entity that voluntarily discontinues using the measurement alternative for an equity security without a readily determinable fair value must measure that security and all identical or similar investments of the same issuer at fair value. Under this guidance, this election is irrevocable and will apply to all future purchases of identical or similar investments of the same issuer. The amendments also clarify other aspects of ASU 2016-01 on how to apply the measurement alternative and the presentation requirements for financial liabilities measured under the fair value option. The adoption of this guidance is contingent on the adoption of ASU 2016-01.

We adopted ASU 2016-01 on January 1, 2018 using the modified retrospective approach and recorded a cumulative-effect adjustment of $1.6 million to reduce opening retained earnings for certain of our other investments that were previously classified as available-for-sale securities and for which changes in fair value were previously included in accumulated other comprehensive income. We also adopted ASU 2018-03 following our adoption of ASU 2016-01 and this adoption did not have any impact on our consolidated financial statements and related disclosures.

ASUs 2014-09, 2016-08, 2016-10, 2016-12, Revenue from Contracts with Customers

In May 2014, the FASB issued ASU 2014-09, which outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. The ASU applies to all contracts with customers except those that are within the scope of other FASB topics, primarily our premium revenues which are covered by ASC 944 - Financial Services - Insurance, and revenues from our investment portfolios which are covered by other FASB topics. While contracts within the scope of ASC 944 are excluded from the scope of the ASU, certain insurance-related contracts are within the scope of the ASU, for example contracts under which service providers charge their customers fixed fees in exchange for an agreement to provide services for an uncertain future event. Certain of the ASU’s provisions also apply to transfers of non-financial assets and include guidance on recognition and measurement.

In March 2016, the FASB also issued ASU 2016-08, Revenue from Contracts with Customers - Principal versus Agent Considerations, which clarifies the implementation guidance for principal versus agent considerations in ASU 2014-09. In April 2016, the FASB then issued ASU 2016-10, Revenue from Contracts with Customers - Identifying Performance Obligations and Licensing, which amends the guidance in ASU 2014-09 related to identifying performance obligations and accounting for licenses of intellectual property. In May 2016, the FASB further issued ASU 2016-12, Revenue from Contracts with Customers - Narrow-Scope Improvements and Practical Expedients, which clarifies the following aspects in ASU 2014-09 - (1a) collectability, (2) presentation of sales taxes and other similar taxes collected from customers, (3) non-cash considerations, (4) contract modifications at transition, (5) completed contracts at transition, and (6) technical correction.

We adopted ASU 2014-09 and the related amendments, as codified in ASC 606 - Revenue from Contracts with Customers, on January 1, 2018 using the modified retrospective method with prior periods not being restated. Premium revenues and those related to our investment portfolios, which collectively comprise most of our total revenues, are within the scope of other FASB topics and therefore are excluded from the scope of the revenue recognition standard. For other revenue types, which are within the scope of the new guidance, we evaluated individual contracts against the provisions of the new guidance to identify any contracts where the timing and measurement of those revenues may differ based upon the new guidance. The adoption did not have a material impact on our consolidated financial statements and related disclosures.

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, 2017 describes accounting pronouncements that were not adopted as of December 31, 2017. Those pronouncements are not yet adopted unless discussed above in "New Accounting Standards Adopted in 2018." In addition, the following relevant pronouncements were issued during the six months ended June 30, 2018 or thereafter and are yet to be adopted.

ASU 2018-11, Targeted Improvements to ASC 842 - Leases and ASU 2018-10, Codification Improvements to ASC 842 - Leases

In July 2018, the FASB issued ASU 2018-11, which adds a transition option for all entities and a practical expedient only for lessors to the ASU 2016-02 - Leases guidance initially issued by the FASB in February 2016 and codified in ASC 842. The transition option which we will elect, allows entities to not 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 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 will still be required to adopt the new leases standard using the modified retrospective transition method required by the standard, 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 July 2018, the FASB also 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 (a) the rate implicit in the lease, (b) impairment of the net investment in the lease, (c) lessee reassessment of lease classification, (d) lessor reassessment of lease term and purchase options, (e) variable payments that depend on an index or rate, and (f) certain transition adjustments.

The amendments arising from both ASU 2018-11 and ASU 2018-10 have the same effective date and transition requirements as ASC 842, which we expect to adopt on January 1, 2019, when it becomes effective. Our implementation of the new leases standard taking into account these amendments to the guidance is ongoing, however we do not anticipate that the adoption of ASU 2016-02 and the amendments in ASU 2018-11 and ASU 2018-10 will have a material impact on our consolidated financial statements and related disclosures.

ASU 2018-09, Codification Improvements

In July 2018, the FASB issued ASU 2018-09, which affects a wide variety of Topics in the Codification and applies to all reporting entities within the scope of the affected accounting guidance. The amendments in the ASU represent changes that clarify, correct errors in, or make minor improvements to the Codification. Ultimately, the amendments make the Codification easier to understand and apply by eliminating inconsistencies and providing clarifications. Some of the amendments in this ASU do not require transition guidance and are effective upon issuance of the ASU, while many of the amendments have transition guidance with effective dates for annual periods beginning after December 15, 2018. The adoption of the amendments in this ASU are not expected to have a material impact on our consolidated financial statements and related disclosures.

Acquisitions

6 Months Ended

Jun. 30, 2018

Business Combinations [Abstract]

Acquisitions

2. ACQUISITIONS

verview

On May 14, 2018, the Company completed the previously announced transaction to acquire all of the outstanding shares and warrants of KaylaRe Holdings, Ltd. ("KaylaRe"). In consideration for the acquired shares and warrants of KaylaRe, the Company issued an aggregate of 2,007,017 ordinary shares to the shareholders of KaylaRe, comprising 1,501,778 voting ordinary shares and 505,239 Series E non-voting ordinary shares. Effective May 14, 2018, we consolidated KaylaRe into our consolidated financial statements, and any balances between KaylaRe and Enstar are now eliminated upon consolidation.

The completion of the KaylaRe transaction enhanced our group capital position and enabled the Company to assume full ownership of another platform from which we can provide non-life run-off solutions to our clients.

Refer to Note 20 - "Related Party Transactions" for additional information relating to KaylaRe.

Purchase Price

The components of the consideration paid to acquire all of the outstanding shares and warrants of KaylaRe were as follows:



Fair value of Enstar ordinary shares issued	$	414,750
Fair value of previously held equity method investment	336,137
Adjustment for the fair value of preexisting relationships	37,169
Total purchase price	$	788,056
Net assets acquired at fair value (excluding preexisting relationships)	$	746,320
Excess of purchase price over fair value of net assets acquired	$	41,736

The purchase price was allocated to the acquired assets and liabilities of KaylaRe based on their estimated fair values at the acquisition date. We recognized goodwill of $41.7 million on the transaction, primarily attributable to (i) the capital synergies from integrating KaylaRe into our group capital structure, (ii) investment management capabilities on a total return basis, and (iii) the incremental acquired capital to be utilized for future non-life run-off transactions.

Fair Value of Enstar Ordinary Shares Issued

The fair value of the Enstar ordinary shares issued was based on the closing price of $206.65 as at May 14, 2018, the date the transaction closed.



Number of Enstar Ordinary shares issued	2,007,017
Closing price of Enstar Ordinary shares as of May 14, 2018	$	206.65
Fair value of Enstar Ordinary shares issued to shareholders of KaylaRe	$	414,750

Fair Value of Previously Held Equity Method Investment

Prior to the close of the transaction, Enstar held a 48.2% interest in KaylaRe, which was accounted for as an equity method investment in accordance with ASC 323 - Investments - Equity Method and Joint Ventures. The acquisition of the remaining 51.8% equity interest in KaylaRe was considered a step acquisition, whereby the Company remeasured the previously held equity method investment to fair value. The Company considered multiple factors in determining the fair value of the previously held equity method investment, including, (i) the price negotiated with the selling shareholders for the 51.8% equity interest in KaylaRe, (ii) recent market transactions for similar companies, and (iii) current trading multiples for comparable companies. Based on this analysis, a valuation multiple of 1.05 to KaylaRe's carrying book value was determined to be appropriate to remeasure the previously held equity method investment at fair value. This resulted in the recognition of a gain of $16.0 million on completion of the step acquisition of KaylaRe, which was recorded in other income (loss) for the three and six months ended June 30, 2018.



Carrying value of previously held equity method investment prior to the close of the transaction	$	320,130
Price-to-book multiple	1.05
Fair value of previously held equity method investment prior to the close of the transaction	$	336,137

Gain recognized on remeasurement of previously held equity method investment to fair value	$	16,007

Adjustment for the Fair Value of Preexisting Relationships

Enstar had contractual preexisting relationships with KaylaRe, which were deemed to be effectively settled at fair value on the acquisition date. The differences between the carrying value and the fair value of the preexisting relationships was included as part of the purchase price in accordance with ASC 805 - Business Combinations. The fair value of the balances relating to preexisting reinsurance relationships with KaylaRe was determined using a discounted cash flow approach and, where applicable, consideration was given to stated contractual settlement provisions, when determining the loss to be recorded on the deemed settlement of these preexisting relationships. The fair values of the balances arising from the non-reinsurance preexisting relationships with KaylaRe were deemed to equal their carrying values given their short-term nature and the expectation that they would all be settled within the next twelve months.

As a result of effectively settling all the contractual preexisting relationships with KaylaRe, the Company recognized a loss of $15.6 million which was recorded in other income (loss) in the three and six months ended June 30, 2018, as summarized below:



ASSETS	Carrying value			Fair value			Loss on deemed settlement
Funds held by reinsured companies	$	386,793		$	386,793		$	—
Deferred acquisition costs/Value of business acquired	33,549			40,268			6,719
TOTAL ASSETS	420,342			427,061			6,719
LIABILITIES
Losses and LAE	339,747			333,205			(6,542		)
Unearned premiums	105,602			105,602			—
Insurance and reinsurance balances payable	25,897			23,559			(2,338		)
Other liabilities	1,864			1,864			—
TOTAL LIABILITIES	473,110			464,230			(8,880		)
NET ASSETS (LIABILITIES)	$	(52,768	)	$	(37,169	)	$	15,599

Fair Value of Net Assets Acquired and Liabilities Assumed

The following table summarizes the fair values of the assets acquired and liabilities assumed (excluding preexisting relationships) in the KaylaRe transaction at the acquisition date, which have all been allocated to the Non-life Run-off segment.



ASSETS
Fixed maturities, trading, at fair value	$	126,393
Other investments, at fair value	626,476
Total investments	752,869
Cash and cash equivalents	5,657
Premiums receivable	10,965
Deferred acquisition costs	275
Other assets	614
TOTAL ASSETS	$	770,380
LIABILITIES
Losses and LAE	$	4,059
Unearned premiums	10,984
Insurance and reinsurance balances payable	13
Other liabilities	9,004
TOTAL LIABILITIES	24,060
NET ASSETS ACQUIRED AT FAIR VALUE	$	746,320

The table below summarizes the results of the KaylaRe operations which are included in our condensed consolidated statement of earnings from the acquisition date to June 30, 2018:



Premiums earned	$	5,381
Incurred losses and LAE	(4,960		)
Acquisition costs	(135		)
Underwriting income	286
Net investment income	791
Net unrealized gains	15,247
	$	16,324

Significant New Business	6 Months Ended
Significant New Business	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
SIGNIFICANT NEW BUSINESS	3. SIGNIFICANT NEW BUSINESS Zurich Australia On February 23, 2018, we entered into a reinsurance agreement with Zurich Australian Insurance Limited, a subsidiary of Zurich Insurance Group ("Zurich") to reinsure its New South Wales Vehicle Compulsory Third Party ("CTP") insurance business. Under the agreement, which was effective as of January 1, 2018, we assumed gross loss reserves of AUD$359.4 million ($280.8 million) in exchange for a reinsurance premium consideration of AUD$343.9 million ($268.7 million). We elected the fair value option for this reinsurance contract and recorded an initial fair value adjustment of AUD$15.5 million ($12.1 million) on the assumed gross loss reserves. Refer to Note 7 - "Fair Value Measurements" for a description of the fair value process and the assumptions made. Following the initial reinsurance transaction, which transferred the economics of the CTP insurance business, we and Zurich are pursuing a portfolio transfer of the CTP insurance business under Division 3A Part III of Australia's Insurance Act 1973 (Cth), which will provide legal finality for Zurich's obligations. The transfer is subject to court, regulatory and other approvals. Neon RITC Transaction On February 16, 2018, we closed the reinsurance-to-close (“RITC”) transaction with Neon Underwriting Limited ("Neon"), under which we reinsured to close the 2015 and prior underwriting years of account (comprising underwriting years 2008 to 2015) of Neon's Syndicate 2468, with effect from January 1, 2018. We assumed gross loss reserves of £403.9 million ($546.3 million) and net loss reserves of £342.1 million ($462.6 million) relating to the portfolio in exchange for a reinsurance premium consideration of £329.1 million ($445.1 million). We elected the fair value option for this reinsurance contract and recorded initial fair value adjustments of $20.6 million and $17.5 million on the gross and net loss reserves assumed, respectively. Refer to Note 7 - "Fair Value Measurements" for a description of the fair value process and the assumptions made. Following the closing of the transaction, we have taken responsibility for claims handling and provided complete finality to Neon's obligations. Novae RITC Transaction On January 29, 2018, we entered into an RITC transaction with AXIS Managing Agency Limited, under which we reinsured to close the 2015 and prior underwriting years of account of Novae Syndicate 2007 ("Novae"), with effect from January 1, 2018. We assumed gross loss reserves of £860.1 million ($1,163.2 million) and net loss reserves of £630.7 million ($853.0 million) relating to the portfolio in exchange for a reinsurance premium consideration of £594.1 million ($803.5 million). We elected the fair value option for this reinsurance contract and recorded initial fair value adjustments of $67.5 million and $49.5 million on the gross and net loss reserves assumed, respectively. Refer to Note 7 - "Fair Value Measurements" for a description of the fair value process and the assumptions made. Following the closing of the transaction, we have taken responsibility for claims handling and provided complete finality to Novae's obligations.

Divestitures, Held-For-Sale Businesses and Discontinued Operations

6 Months Ended

Jun. 30, 2018

Discontinued Operations and Disposal Groups [Abstract]

DIVESTITURES, HELD-FOR-SALE BUSINESSES AND DISCONTINUED OPERATIONS

4. DIVESTITURES, HELD-FOR-SALE BUSINESSES AND DISCONTINUED OPERATIONS

Pavonia

On December 29, 2017, the Company completed the previously announced sale of its subsidiary, Pavonia Holdings (US) Inc. ("Pavonia"), to Southland National Holdings, Inc. ("Southland"), a Delaware corporation and a subsidiary of Global Bankers Insurance Group, LLC. The aggregate purchase price was $120.0 million. The Company used the proceeds to make repayments under its revolving credit facility.

Pavonia owns Pavonia Life Insurance Company of Michigan (“PLIC MI”) and Enstar Life (US), Inc. Pursuant to the amended stock purchase agreement between the Company and Southland, which partially restructured the transaction, Southland will acquire Pavonia Life Insurance Company of New York ("PLIC NY") for $13.1 million in a second closing that is expected to occur in 2018, subject to regulatory approval. The additional purchase price represents the cash consideration we paid to PLIC MI when we acquired PLIC NY from PLIC MI as a result of the restructuring of the first closing of the transaction.

Pavonia was a substantial portion of our previously reported Life and Annuities segment. We classified the assets and liabilities of the businesses to be sold as held-for-sale. The following table summarizes the components of assets and liabilities held-for-sale on our consolidated balance sheet as at December 31, 2017:



	December 31, 2017
Assets:
Fixed maturities, trading, at fair value	$	20,770
Equities, trading, at fair value	765
Cash and cash equivalents	6,314
Restricted cash and cash equivalents	13
Reinsurance balances recoverable	1,728
Other assets	269
Assets of businesses held for sale	29,859
Less: Accrual of loss on sale	(5,508		)
Total assets held for sale	$	24,351

Liabilities:
Policy benefits for life and annuity contracts	$	10,666
Other liabilities	605
Total liabilities held for sale	$	11,271

As at December 31, 2017, included in the table above were restricted investments of $1.4 million.

As at June 30, 2018, included within Other assets and Other liabilities on our consolidated balance sheet were amounts of $23.0 million and $10.0 million, respectively, relating to PLIC NY.

The Pavonia business qualifies as a discontinued operation. The following table summarizes the components of net earnings from discontinued operations on the unaudited condensed consolidated statements of earnings for the three and six months ended June 30, 2017:



	Three Months Ended June 30,			Six Months Ended June 30,
	2017			2017
INCOME
Net premiums earned	$	13,605		$	27,930
Net investment income	10,277			20,306
Net realized and unrealized gains	1,154			2,776
Other income	395			755
	25,431			51,767
EXPENSES
Life and annuity policy benefits	24,112			44,782
Acquisition costs	2,280			4,316
General and administrative expenses	3,718			6,775
Other expenses	—			(16		)
	30,110			55,857
LOSS BEFORE INCOME TAXES	(4,679		)	(4,090		)
INCOME TAXES	(192		)	(410		)
NET LOSS FROM DISCONTINUED OPERATIONS	$	(4,871	)	$	(4,500	)

The following table presents the cash flows of Pavonia for the six months ended June 30, 2017:



	Six Months Ended June 30,
	2017
Operating activities	$	23,540
Investing activities	5,244
Change in cash and cash equivalents	$	28,784

Laguna

On August 29, 2017, we completed a transaction to sell Laguna Life DAC (“Laguna”) for total consideration of €25.6 million (approximately $30.8 million) to a subsidiary of Monument Re Limited ("Monument"). We have an investment in Monument, as described further in Note 20 - "Related Party Transactions". Laguna was classified as held-for-sale during 2017 prior to its sale.

The net losses relating to Laguna for the three and six months ended June 30, 2017 were $0.9 million and $1.1 million, respectively. These amounts were not significant to our consolidated operations and therefore we have not classified Laguna as a discontinued operation for prior periods. As at June 30, 2017 we recorded a loss on the sale of Laguna of $9.6 million, which was included in earnings from continuing operations before income taxes in our consolidated statement of earnings. The total loss recorded on the sale of Laguna, for the year ended December 31, 2017 was $16.3 million, which included a cumulative currency translation adjustment balance of $6.3 million, which upon completion of the sale during the third quarter of 2017 was reclassified from accumulated other comprehensive income and included in earnings as a component of the loss on sale of Laguna.

Investments

6 Months Ended

Jun. 30, 2018

Investments, Debt and Equity Securities [Abstract]

INVESTMENTS

5. 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 carried at fair value; and (iii) other investments carried at either fair value or cost.

Trading

The fair values of our fixed maturity investments, short-term investments and equities classified as trading were as follows:



	June 30, 2018		December 31, 2017
U.S. government and agency	$	536,132	$	554,036
Non-U.S. government	979,974		607,132
Corporate	3,787,366		3,363,060
Municipal	89,339		100,221
Residential mortgage-backed	306,025		288,713
Commercial mortgage-backed	403,001		421,548
Asset-backed	586,488		541,574
Total fixed maturity and short-term investments	6,688,325		5,876,284
Equities — U.S.	90,256		106,363
Equities — International	40,148		240
	$	6,818,729	$	5,982,887

Included within residential and commercial mortgage-backed securities as at June 30, 2018 were securities issued by U.S. governmental agencies with a fair value of $160.2 million (as at December 31, 2017: $152.4 million). Included within corporate securities as at June 30, 2018 were senior secured loans of $13.9 million (as at December 31, 2017: $68.9 million).

The contractual maturities of our fixed maturity and short-term investments classified as trading 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 at June 30, 2018	Amortized Cost		Fair Value		% of Total Fair Value
One year or less	$	480,852	$	475,705	7.1	%
More than one year through two years	546,766		537,849		8.0	%
More than two years through five years	1,672,267		1,633,309		24.4	%
More than five years through ten years	1,476,591		1,435,235		21.5	%
More than ten years	1,325,143		1,310,713		19.6	%
Residential mortgage-backed	304,249		306,025		4.6	%
Commercial mortgage-backed	415,135		403,001		6.0	%
Asset-backed	584,876		586,488		8.8	%
	$	6,805,879	$	6,688,325	100.0	%

Available-for-sale

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



As at June 30, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses Non-OTTI			Fair Value
U.S. government and agency	$	2,429	$	—	$	(9	)	$	2,420
Non-U.S. government	75,679		1,423		(915		)	76,187
Corporate	86,696		1,472		(1,184		)	86,984
Municipal	3,743		1		(32		)	3,712
Residential mortgage-backed	18		—		—			18
	$	168,565	$	2,896	$	(2,140	)	$	169,321



As at December 31, 2017	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses Non-OTTI			Fair Value
U.S. government and agency	$	4,210	$	—	$	(23	)	$	4,187
Non-U.S. government	84,776		1,249		(588		)	85,437
Corporate	113,561		2,436		(876		)	115,121
Municipal	5,146		8		(18		)	5,136
Residential mortgage-backed	31		—		—			31
Asset-backed	373		—		—			373
	$	208,097	$	3,693	$	(1,505	)	$	210,285

The contractual maturities of our fixed maturity investments classified as available-for-sale 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 at June 30, 2018	Amortized Cost		Fair Value		% of Total Fair Value
One year or less	$	20,321	$	19,692	11.6	%
More than one year through two years	20,422		20,211		11.9	%
More than two years through five years	40,382		40,544		24.0	%
More than five years through ten years	56,263		56,890		33.6	%
More than ten years	31,159		31,966		18.9	%
Residential mortgage-backed	18		18		—	%
	$	168,565	$	169,321	100.0	%

Gross Unrealized Losses

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 at June 30, 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	$	2,293	$	(8	)	$	127	$	(1	)	$	2,420	$	(9	)
Non-U.S. government	4,270		(390		)	18,007		(525		)	22,277		(915		)
Corporate	7,266		(822		)	24,914		(362		)	32,180		(1,184		)
Municipal	367		(7		)	2,913		(25		)	3,280		(32		)
Total fixed maturity investments	$	14,196	$	(1,227	)	$	45,961	$	(913	)	$	60,157	$	(2,140	)



	12 Months or Greater					Less Than 12 Months					Total
As at December 31, 2017	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	$	2,344	$	(16	)	$	1,842	$	(7	)	$	4,186	$	(23	)
Non-U.S. government	11,101		(373		)	20,965		(215		)	32,066		(588		)
Corporate	9,177		(807		)	24,200		(69		)	33,377		(876		)
Municipal	369		(5		)	3,605		(13		)	3,974		(18		)
Total fixed maturity investments	$	22,991	$	(1,201	)	$	50,612	$	(304	)	$	73,603	$	(1,505	)

As at June 30, 2018 and December 31, 2017, the number of securities classified as available-for-sale in an unrealized loss position was 96. Of these securities, the number of securities that had been in an unrealized loss position for twelve months or longer was 30 and 37, respectively.

Other-Than-Temporary Impairment

For the six months ended June 30, 2018 and 2017, we did not recognize any other-than-temporary impairment losses on our available-for-sale securities. We determined that no credit losses existed as at June 30, 2018 or December 31, 2017. A description of our other-than-temporary impairment process is included in 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, 2017. There were no changes to our process during the six months ended June 30, 2018.

Credit Ratings

The following table sets forth the credit ratings of our fixed maturity and short-term investments as at June 30, 2018:



	Amortized Cost		Fair Value		% of Total Investments		AAA Rated			AA Rated			A Rated			BBB Rated			Non- Investment Grade			Not Rated
Fixed maturity and short-term investments
U.S. government and agency	$	544,615	$	538,552	7.9	%	$	537,959		$	593		$	—		$	—		$	—		$	—
Non-U.S. government	1,061,120		1,056,161		15.4	%	375,722			568,567			46,510			59,407			5,955			—
Corporate	3,970,353		3,874,350		56.5	%	169,098			461,745			2,073,323			1,064,563			105,329			292
Municipal	94,078		93,051		1.4	%	18,303			58,518			12,811			3,419			—			—
Residential mortgage-backed	304,267		306,043		4.4	%	187,130			4,046			13,154			410			97,140			4,163
Commercial mortgage-backed	415,135		403,001		5.9	%	210,884			47,233			65,830			57,420			9,822			11,812
Asset-backed	584,876		586,488		8.5	%	263,152			52,827			117,250			75,577			77,211			471
Total	$	6,974,444	$	6,857,646	100.0	%	$	1,762,248		$	1,193,529		$	2,328,878		$	1,260,796		$	295,457		$	16,738
% of total fair value							25.7		%	17.4		%	34.0		%	18.4		%	4.3		%	0.2		%

Other Investments, at fair value

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



	June 30, 2018		December 31, 2017
Private equities and private equity funds	$	252,965	$	289,556
Fixed income funds	342,166		229,999
Hedge funds	670,963		63,773
Equity funds	387,490		249,475
CLO equities	53,840		56,765
CLO equity fund	40,864		12,840
Private credit funds	14,319		10,156
Call options on equity	4,998		—
Other	728		828
	$	1,768,333	$	913,392

The valuation of our other investments is described in Note 7 - "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:


•	Private equities and private equity funds invest primarily in the financial services industry. All of our investments in private equities and 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.

•

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. The funds have liquidity terms that vary from daily up to 45 days notice.

•

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. Our hedge funds have various lock-up periods of up to three years and redemption terms, predominantly 60 and 90 days. Certain of our hedge funds which have exceeded that lock up period are currently eligible for redemption while others are still in the lock-up period.


•	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.


•	CLO equities comprise investments in the equity tranches of term-financed securitizations of diversified pools of corporate bank loans. CLO equities denote direct investments by us in these securities.


•	CLO equity fund invests primarily in the equity tranches of term-financed securitizations of diversified pools of corporate bank loans. The fund has a fair value of $40.9 million and 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.


•	Call options on equities comprise directly held options to purchase the common equity of publicly traded corporations.


•	Other primarily comprises 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 December 31, 2017 and June 30, 2018 was primarily attributable to $626.5 million of other investments acquired as part of the KaylaRe acquisition and net additional subscriptions of $231.6 million.

Investments of $0.4 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.

As at June 30, 2018, we had unfunded commitments to other investments of $200.0 million.

Other Investments, at cost

During the three months ended June 30, 2018 we sold our investments in life settlement contracts, which were carried at cost. During the six months ended June 30, 2018 and 2017, net investment income included $6.5 million and $9.3 million, respectively, related to investments in life settlements. There were impairment charges of $6.6 million and $6.3 million recognized in net realized and unrealized gains/losses during the six months ended June 30, 2018 and 2017, respectively, related to investments in life settlements. The following table presents further information regarding our investments in life settlements as at December 31, 2017:



	December 31, 2017
	Number of Contracts	Carrying Value		Face Value (Death Benefits)
Remaining Life Expectancy of Insureds:
0 – 1 year	—	$	—	$	—
1 – 2 years	11	17,655		29,471
2 – 3 years	10	7,524		19,906
3 – 4 years	20	16,119		32,411
4 – 5 years	13	13,960		32,730
Thereafter	162	70,363		390,843
Total	216	$	125,621	$	505,361

Remaining life expectancy for year 0-1 in the table above references policies whose current life expectancy is less than 12 months as at the reporting date. Remaining life expectancy is not an indication of expected maturity. Actual maturity in any category above may vary significantly (either earlier or later) from the remaining life expectancies reported.

Net Investment Income

Major categories of net investment income for the three and six months ended June 30, 2018 and 2017 are summarized as follows:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Fixed maturity investments	$	48,147		$	33,741		$	92,035		$	64,071
Short-term investments and cash and cash equivalents	3,096			2,801			5,178			5,441
Funds held	2,754			311			5,883			350
Funds held - directly managed	9,588			8,603			18,214			15,605
Investment income from fixed maturities and cash and cash equivalents	63,585			45,456			121,310			85,467
Equity securities	1,352			1,137			2,842			1,863
Other investments	2,962			3,387			6,276			6,896
Life settlements and other	1,116			2,687			7,775			9,583
Investment income from equities and other investments	5,430			7,211			16,893			18,342
Gross investment income	69,015			52,667			138,203			103,809
Investment expenses	(2,546		)	(3,250		)	(5,415		)	(5,653		)
Net investment income	$	66,469		$	49,417		$	132,788		$	98,156

Net Realized and Unrealized Gains and Losses

Components of net realized and unrealized gains and losses for the three and six months ended June 30, 2018 and 2017 were as follows:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, available-for-sale	$	20		$	177		$	27		$	337
Gross realized losses on fixed maturity securities, available-for-sale	(41		)	(75		)	(78		)	(86		)
Net realized losses on fixed maturity securities, trading	(3,566		)	65			(10,513		)	(987		)
Net realized gains on equity securities, trading	2,000			236			2,903			810
Net realized losses on funds held - directly managed	(1,041		)	(289		)	(945		)	(4,142		)
Total net realized gains (losses) on sale	$	(2,628	)	$	114		$	(8,606	)	$	(4,068	)
Net unrealized gains (losses):
Fixed maturity securities, trading	$	(45,967	)	$	11,226		$	(146,268	)	$	34,542
Equity securities, trading	487			1,871			4,322			10,557
Other Investments	7,791			19,696			(1,871		)	43,205
Change in fair value of embedded derivative on funds held – directly managed	(13,044		)	17,912			(40,925		)	24,840
Change in value of fair value option on funds held - directly managed	(1,057		)	1,058			(4,100		)	1,320
Total net unrealized gains (losses)	(51,790		)	51,763			(188,842		)	114,464
Net realized and unrealized gains (losses)	$	(54,418	)	$	51,877		$	(197,448	)	$	110,396

The gross realized gains and losses on available-for-sale securities included in the table above resulted from sales of $3.0 million and $12.3 million for the three months ended June 30, 2018 and 2017, respectively, and $10.5 million and $21.6 million for the six months ended June 30, 2018 and 2017, respectively.

Restricted Assets

We are required to maintain investments and cash and cash equivalents on deposit to support our insurance and reinsurance operations. The investments and cash and cash equivalents on deposit are available to settle insurance and reinsurance liabilities. We also utilize trust accounts to collateralize business with our insurance and reinsurance counterparties. These trust accounts generally take the place of letter of credit requirements. The assets in trusts as collateral are primarily highly rated fixed maturity securities. The carrying value of our restricted assets, including restricted cash of $363.9 million and $257.7 million, as at June 30, 2018 and December 31, 2017, respectively, was as follows:



	June 30, 2018		December 31, 2017
Collateral in trust for third party agreements	$	3,399,091	$	3,118,892
Assets on deposit with regulatory authorities	585,922		599,829
Collateral for secured letter of credit facilities	133,277		151,467
Funds at Lloyd's ⁽¹⁾	417,333		234,833
	$	4,535,623	$	4,105,021

⁽¹⁾Our underwriting 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. On February 8, 2018, we amended and restated our unsecured letter of credit agreement for Funds at Lloyd's purposes ("FAL Facility") to issue up to $325.0 million letters of credit, with a provision to increase the facility up to $400.0 million, subject to lenders approval. The FAL Facility is available to satisfy our Funds at Lloyd's requirements and expires in 2022. As at June 30, 2018, our combined Funds at Lloyd's were comprised of cash and investments of $417.3 million and unsecured letters of credit of $295.0 million.

The increase in the collateral in trust for third-party agreements and Funds at Lloyd's was primarily due to the loss portfolio transfer reinsurance transactions as described in Note 3 - "Significant New Business".

Funds Held - Directly Managed

6 Months Ended

Jun. 30, 2018

Investments, Debt and Equity Securities [Abstract]

FUNDS HELD - DIRECTLY MANAGED

6. FUNDS HELD - DIRECTLY MANAGED

Funds held - directly managed is comprised of the following:

•

The funds held balance in relation to the Allianz transaction, described in Note 4 - "Significant New Business" in our consolidated financial statements in our Annual Report on Form 10-K for the year ended December 31, 2017. This receives a variable return reflecting the economics of the investment portfolio underlying the funds held asset and qualifies as an embedded derivative. We have recorded the aggregate of the funds held, typically held at cost, and the embedded derivative as a single amount in our consolidated balance sheet. As at June 30, 2018 and December 31, 2017, the funds held at cost had a carrying value of $1,087.6 million and $994.8 million, respectively, and the embedded derivative had a fair value of $(36.3) million and $4.7 million, respectively, the aggregate of which was $1,051.3 million and $999.5 million, respectively, as included in the table below.


•	The funds held balance in relation to the QBE reinsurance transaction described in Note 4 - "Significant New Business" in our consolidated financial statements in our Annual Report on Form 10-K for the year ended December 31, 2017, for which we elected the fair value option.

The following table presents the fair values of assets and liabilities underlying the funds held - directly managed account as at June 30, 2018 and December 31, 2017:



	June 30, 2018		December 31, 2017
Fixed maturity investments:
U.S. government and agency	$	87,017	$	69,850
Non-U.S. government	22,625		2,926
Corporate	672,437		695,490
Municipal	58,933		58,930
Residential mortgage-backed	60,260		29,439
Commercial mortgage-backed	221,133		211,186
Asset-backed	98,339		97,565
Total fixed maturity investments	$	1,220,744	$	1,165,386
Other assets	9,152		14,554
	$	1,229,896	$	1,179,940

The contractual maturities of the fixed maturity investments underlying the funds held - directly managed account 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 at June 30, 2018	Amortized Cost		Fair Value		% of Total Fair Value
One year or less	$	23,555	$	23,456	1.9	%
More than one year through two years	74,264		73,553		6.0	%
More than two years through five years	245,586		239,757		19.6	%
More than five years through ten years	268,392		256,849		21.1	%
More than ten years	256,716		247,397		20.3	%
Residential mortgage-backed	61,362		60,260		4.9	%
Commercial mortgage-backed	231,947		221,133		18.1	%
Asset-backed	98,360		98,339		8.1	%
	$	1,260,182	$	1,220,744	100.0	%

Credit Ratings

The following table sets forth the credit ratings of the fixed maturity investments underlying the funds held - directly managed account as at June 30, 2018:



	Amortized Cost		Fair Value		% of Total Investments		AAA Rated			AA Rated			A Rated			BBB Rated			Non- Investment Grade

U.S. government and agency	$	87,996	$	87,017	7.1	%	$	87,017		$	—		$	—		$	—		$	—
Non-U.S. government	22,524		22,625		1.9	%	—			3,797			12,162			6,666			—
Corporate	699,234		672,437		55.1	%	7,783			25,828			309,495			327,782			1,549
Municipal	58,759		58,933		4.8	%	—			20,725			30,854			7,354			—
Residential mortgage-backed	61,362		60,260		4.9	%	59,733			—			—			—			527
Commercial mortgage-backed	231,947		221,133		18.1	%	212,766			6,401			1,966			—			—
Asset-backed	98,360		98,339		8.1	%	85,027			13,312			—			—			—
Total	$	1,260,182	$	1,220,744	100.0	%	$	452,326		$	70,063		$	354,477		$	341,802		$	2,076
% of total fair value							37.1		%	5.7		%	29.0		%	28.0		%	0.2		%

Net Investment Income

Major categories of net investment income underlying the funds held - directly managed for the three and six months ended June 30, 2018 and 2017 are summarized as follows:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Fixed maturity investments	$	9,817		$	8,817		$	18,635		$	16,302
Short-term investments and cash and cash equivalents	58			62			137			127
Gross investment income	9,875			8,879			18,772			16,429
Investment expenses	(287		)	(276		)	(558		)	(824		)
Investment income on funds held - directly managed	$	9,588		$	8,603		$	18,214		$	15,605

Net Realized Gains (Losses) and Change in Fair Value due to Embedded Derivative and Fair Value Option

Net realized gains (losses) and change in fair value for the three and six months ended June 30, 2018 and 2017 are summarized as follows:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Net realized losses on fixed maturity securities	$	(1,041	)	$	(289	)	$	(945	)	$	(4,142	)
Change in fair value of embedded derivative	(13,044		)	17,912			(40,925		)	24,840
Change in value of fair value option on funds held - directly managed	(1,057		)	1,058			(4,100		)	1,320
Net realized gains (losses) and change in fair value of funds held - directly managed	$	(15,142	)	$	18,681		$	(45,970	)	$	22,018

Fair Value Measurements

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

7. FAIR VALUE MEASUREMENTS

Fair Value Hierarchy

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


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


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


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

In addition, certain of our other investments are measured at fair value using net asset value ("NAV") per share (or its equivalent) as a practical expedient and have not been classified within the fair value hierarchy above. We have categorized our 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:



	June 30, 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	$	—	$	538,552	$	—	$	—	$	538,552
Non-U.S. government	—		1,056,161		—		—		1,056,161
Corporate	—		3,846,527		27,823		—		3,874,350
Municipal	—		93,051		—		—		93,051
Residential mortgage-backed	—		306,043		—		—		306,043
Commercial mortgage-backed	—		387,675		15,326		—		403,001
Asset-backed	—		539,880		46,608		—		586,488
	$	—	$	6,767,889	$	89,757	$	—	$	6,857,646
Equities:
Equities — U.S.	$	86,407	$	1,833	$	2,016	$	—	$	90,256
Equities — International	38,039		2,109		—		—		40,148
	$	124,446	$	3,942	$	2,016	$	—	$	130,404
Other investments:
Private equities and private equity funds	$	—	$	—	$	—	$	252,965	$	252,965
Fixed income funds	—		322,069		—		20,097		342,166
Hedge funds	—		—		—		670,963		670,963
Equity funds	—		115,794		—		271,696		387,490
CLO equities	—		—		53,840		—		53,840
CLO equity fund	—		—		—		40,864		40,864
Private credit funds	—		—		—		14,319		14,319
Call options on equities	—		4,998		—		—		4,998
Other	—		—		314		414		728
	$	—	$	442,861	$	54,154	$	1,271,318	$	1,768,333
Total Investments	$	124,446	$	7,214,692	$	145,927	$	1,271,318	$	8,756,383
Funds Held - Directly Managed:
U.S. government and agency	$	—	$	87,017	$	—	$	—	$	87,017
Non-U.S. government	—		22,625		—		—		22,625
Corporate	—		672,437		—		—		672,437
Municipal	—		58,933		—		—		58,933
Residential mortgage-backed	—		60,260		—		—		60,260
Commercial mortgage-backed	—		221,133		—		—		221,133
Asset-backed	—		97,840		499		—		98,339
Other assets	—		9,152		—		—		9,152
	$	—	$	1,229,397	$	499	$	—	$	1,229,896

Reinsurance balances recoverable:	$	—	$	—	$	837,373	$	—	$	837,373

Other Assets:
Derivative Instruments	$	—	$	12,317	$	—	$	—	$	12,317
	$	—	$	12,317	$	—	$	—	$	12,317

Losses and LAE:	$	—	$	—	$	3,221,366	$	—	$	3,221,366

Other Liabilities:
Derivative Instruments	$	—	$	77	$	—	$	—	$	77
	$	—	$	77	$	—	$	—	$	77



	December 31, 2017
	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	$	—	$	558,223	$	—	$	—	$	558,223
Non-U.S. government	—		692,569		—		—		692,569
Corporate	—		3,411,003		67,178		—		3,478,181
Municipal	—		105,357		—		—		105,357
Residential mortgage-backed	—		285,664		3,080		—		288,744
Commercial mortgage-backed	—		400,054		21,494		—		421,548
Asset-backed	—		514,055		27,892		—		541,947
	$	—	$	5,966,925	$	119,644	$	—	$	6,086,569
Equities:
Equities — U.S.	$	103,652	$	2,711	$	—	$	—	$	106,363
Equities — International	—		240		—		—		240
	$	103,652	$	2,951	$	—	$	—	$	106,603
Other investments:
Private equities and private equity funds	$	—	$	—	$	—	$	289,556	$	289,556
Fixed income funds	—		202,570		—		27,429		229,999
Hedge funds	—		—		—		63,773		63,773
Equity funds	—		121,046		—		128,429		249,475
CLO equities	—		—		56,765		—		56,765
CLO equity funds	—		—		—		12,840		12,840
Private credit funds	—		—		—		10,156		10,156
Other	—		—		314		514		828
	$	—	$	323,616	$	57,079	$	532,697	$	913,392
Total Investments	$	103,652	$	6,293,492	$	176,723	$	532,697	$	7,106,564
Funds Held - Directly Managed:
U.S. government and agency	$	—	$	69,850	$	—	$	—	$	69,850
Non-U.S. government	—		2,926		—		—		2,926
Corporate	—		695,490		—		—		695,490
Municipal	—		58,930		—		—		58,930
Residential mortgage-backed	—		29,439		—		—		29,439
Commercial mortgage-backed	—		211,186		—		—		211,186
Asset-backed	—		97,565		—		—		97,565
Other assets	—		14,554		—		—		14,554
	$	—	$	1,179,940	$	—	$	—	$	1,179,940

Reinsurance balances recoverable:	$	—	$	—	$	542,224	$	—	$	542,224

Other Assets:
Derivative Instruments	$	—	$	319	$	—	$	—	$	319
	$	—	$	319	$	—	$	—	$	319

Losses and LAE:	$	—	$	—	$	1,794,669	$	—	$	1,794,669

Other Liabilities:
Derivative Instruments	$	—	$	7,246	$	—	$	—	$	7,246
	$	—	$	7,246	$	—	$	—	$	7,246

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 are predominantly traded on the major exchanges and are primarily managed by our external advisors. We use an internationally recognized pricing service to estimate the fair value of our equities. Our equities are widely diversified and there is no significant concentration in any specific industry.

We have categorized our publicly quoted equity securities as Level 1 within the fair value hierarchy because their fair values are based on unadjusted quoted prices for identical securities in active markets. Other equity securities have been categorized as either Level 2 if their fair values are based on observable market data or Level 3 if their fair values are based on unobservable inputs where there is minimal or no market activity.

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 private equities and 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.

•

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 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.

•

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 valued 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 CLO equity funds, we measure fair value by obtaining the most recently available NAV as advised by the external fund manager or third party administrator. The fair values of these investments are 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.


•	For our investments in call options on publicly traded equities, we measure fair value by obtaining the latest option price as of our reporting date. These are classified as Level 2.

Insurance Contracts - Fair Value Option

The Company uses an internal model to calculate the fair value of the liability for losses and loss adjustment expenses and reinsurance balances recoverable asset 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 Instruments

The fair values of our foreign currency exchange contracts, as described in Note 8 - "Derivative and Hedging Instruments" are classified as Level 2. The fair values are based upon prices in active markets for identical contracts.

Level 3 Measurements and Changes in Leveling

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

The following tables present a reconciliation of the beginning and ending balances for all investments measured at fair value on a recurring basis using Level 3 inputs during the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30, 2018
	Corporate			Residential mortgage-backed			Commercial mortgage-backed			Asset-backed			Equities - U.S.		Other Investments			Total
Beginning fair value	$	86,027		$	1,907		$	17,634		$	21,997		$	—	$	56,659		$	184,224
Purchases	971			—			—			28,291			2,000		622			31,884
Sales	(53,873		)	(36		)	(1,150		)	(8		)	—		(600		)	(55,667		)
Total realized and unrealized gains (losses)	(258		)	(8		)	(31		)	(117		)	16		(2,527		)	(2,925		)
Transfer into Level 3 from Level 2	—			—			—			2,079			—		—			2,079
Transfer out of Level 3 into Level 2	(5,044		)	(1,863		)	(1,127		)	(5,634		)	—		—			(13,668		)
Ending fair value	$	27,823		$	—		$	15,326		$	46,608		$	2,016	$	54,154		$	145,927



	Three Months Ended June 30, 2017
	Corporate			Residential mortgage-backed			Commercial mortgage-backed			Asset-backed			Equities - U.S.		Other Investments			Total
Beginning fair value	$	56,179		$	—		$	24,852		$	29,082		$	—	$	69,627		$	179,740
Purchases	6,679			711			10,347			—			—		292			18,029
Sales	(6,461		)	(5		)	(734		)	(7,118		)	—		—			(14,318		)
Total realized and unrealized gains (losses)	191			(13		)	436			(72		)	—		(450		)	92
Transfer into Level 3 from Level 2	3,378			—			4,015			31,775			—		—			39,168
Transfer out of Level 3 into Level 2	(5,610		)	—			(16,051		)	(13,234		)	—		(12,350		)	(47,245		)
Ending fair value	$	54,356		$	693		$	22,865		$	40,433		$	—	$	57,119		$	175,466



	Six Months Ended June 30, 2018
	Corporate			Residential mortgage-backed			Commercial mortgage-backed			Asset-backed			Equities - U.S.		Other Investments			Total
Beginning fair value	$	67,178		$	3,080		$	21,494		$	27,892		$	—	$	57,079		$	176,723
Purchases	11,803			—			1,803			29,591			2,000		752			45,949
Sales	(60,910		)	(1,184		)	(1,727		)	(3,812		)	—		(600		)	(68,233		)
Total realized and unrealized gains (losses)	(63		)	(33		)	52			(71		)	16		(3,077		)	(3,176		)
Transfer into Level 3 from Level 2	15,259			—			4,897			2,079			—		—			22,235
Transfer out of Level 3 into Level 2	(5,444		)	(1,863		)	(11,193		)	(9,071		)	—		—			(27,571		)
Ending fair value	$	27,823		$	—		$	15,326		$	46,608		$	2,016	$	54,154		$	145,927



	Six Months Ended June 30, 2017
	Corporate			Residential mortgage-backed			Commercial mortgage-backed			Asset-backed			Equities - U.S.		Other Investments			Total
Beginning fair value	$	74,534		$	—		$	12,213		$	14,692		$	—	$	76,878		$	178,317
Purchases	15,568			711			10,347			1,380			—		292			28,298
Sales	(25,117		)	(5		)	(734		)	(7,361		)	—		—			(33,217		)
Total realized and unrealized gains (losses)	650			(13		)	331			209			—		(7,701		)	(6,524		)
Transfer into Level 3 from Level 2	4,945			—			17,916			49,336			—		—			72,197
Transfer out of Level 3 into Level 2	(16,224		)	—			(17,208		)	(17,823		)	—		(12,350		)	(63,605		)
Ending fair value	$	54,356		$	693		$	22,865		$	40,433		$	—	$	57,119		$	175,466

Net realized and unrealized gains related to Level 3 assets in the tables above are included in net realized and unrealized (losses) gains 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 Option

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 during the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30, 2018						Three Months Ended June 30, 2017
	Liability for losses and LAE			Reinsurance balances recoverable			Liability for losses and LAE			Reinsurance balances recoverable
Beginning fair value	$	3,519,453		$	888,736		$	1,924,829		$	551,253
Assumed business	—			—			—			—
Changes in nominal amounts:
Net incurred losses and LAE	(48,899		)	3,860			(26,407		)	(2,095		)
Paid losses	(145,676		)	(35,389		)	(39,686		)	(4,488		)
Changes in fair value:
Discounted cash flows	29,141			2,067			(3,354		)	5,947
Risk margin	(11,595		)	(1,754		)	(4,563		)	(632		)
Effect of exchange rate movements	(121,058		)	(20,147		)	41,478			4,774
Ending fair value	$	3,221,366		$	837,373		$	1,892,297		$	554,759



	Six Months Ended June 30, 2018						Six Months Ended June 30, 2017
	Liability for losses and LAE			Reinsurance balances recoverable			Liability for losses and LAE			Reinsurance balances recoverable
Beginning fair value	$	1,794,669		$	542,224		$	—		$	—
Assumed business	1,890,061			372,780			1,966,843			565,824
Changes in nominal amounts:
Net incurred losses and LAE	(55,196		)	2,384			(32,645		)	(2,095		)
Paid losses	(304,048		)	(53,535		)	(100,053		)	(21,494		)
Changes in fair value:
Discounted cash flows	(20,863		)	(13,882		)	17,013			8,413
Risk margin	(18,746		)	(2,719		)	(9,052		)	(1,702		)
Effect of exchange rate movements	(64,511		)	(9,879		)	50,191			5,813
Ending fair value	$	3,221,366		$	837,373		$	1,892,297		$	554,759

Changes in fair value related to Level 3 assets and liabilities in the tables above are included in net incurred losses and LAE in our unaudited condensed consolidated statements of earnings.

Below is a summary of the quantitative information regarding the significant observable and unobservable inputs used in the internal model to determine fair value on a recurring basis as at June 30, 2018 and December 31, 2017:



		June 30, 2018	December 31, 2017
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)	5.0%	5.0%
Internal model	Weighted average cost of capital (U)	8.5%	8.5%
Internal model	Duration - liability (U)	7.95 years	11.41 years
Internal model	Duration - reinsurance balances recoverable (U)	8.94 years	11.66 years

The fair value of the liability for losses and LAE and reinsurance balances recoverable 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. 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.


•	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. 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.


•	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. 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.


•	An acceleration of the estimated payment pattern would result in an increase in the fair value of the liability for losses and LAE and reinsurance balances recoverable. Conversely, a deceleration of the estimated payment pattern would result in a decrease in the fair value of the liability for losses and LAE and reinsurance balances recoverable.

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 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.

Disclosure of Fair Values for Financial Instruments Carried at Cost

During the three months ended June 30, 2018, we sold our investments in life settlement contracts, which were carried at cost. As at December 31, 2017, investments in life settlement contracts were carried at cost of $125.6 million, respectively, and their fair values were $131.9 million.

The fair value of investments in life settlement contracts is determined using a discounted cash flow methodology that utilizes unobservable inputs. Due to the individual nature of each investment in life settlement contracts and the illiquidity of the existing market, significant inputs to the fair value include our estimates of premiums necessary to keep the policies in-force, and our assumptions for mortality and discount rates. Our mortality assumptions are based on a combination of medical underwriting information obtained from a third-party underwriter for each referenced life and internal proprietary mortality studies of older aged U.S. insured lives. These assumptions are used to develop an estimate of future net cash flows that, after discounting, are intended to be reflective of the asset's value in the life settlement market.

As at June 30, 2018, our 4.5% Senior Notes due 2022 were carried at amortized cost of $347.7 million while the fair value based on observable market pricing from a third party pricing service was $348.4 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 June 30, 2018 and December 31, 2017.

- 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

Derivative and Hedging Instruments

6 Months Ended

Jun. 30, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

DERIVATIVE AND HEDGING INSTRUMENTS

8. DERIVATIVE AND HEDGING INSTRUMENTS

Foreign Currency Hedging of Net Investments in Foreign Operations

We use foreign currency forward exchange rate contracts in qualifying hedging relationships to hedge the foreign currency exchange rate risk associated with certain of our net investments in foreign operations. At June 30, 2018 and December 31, 2017, 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 liabilities related to our qualifying foreign currency forward exchange rate contracts as at June 30, 2018 and December 31, 2017.



	June 30, 2018						December 31, 2017
			Fair Value						Fair Value
	Gross Notional Amount		Assets		Liabilities		Gross Notional Amount		Assets		Liabilities
Foreign exchange forward - AUD	$	27,358	$	571	$	—	$	32,810	$	—	$	965
Foreign exchange forward - CAD	—		—		—		27,141		11		512
Total qualifying hedges	$	27,358	$	571	$	—	$	59,951	$	11	$	1,477

The Canadian Dollar ("CAD") foreign currency contract that we had in place to hedge the net investment in our CAD denominated operations was discontinued effective December 31, 2017 following the disposal of those operations.

The following table presents the amounts of the net gains and losses deferred in the currency 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 and six months ended June 30, 2018 and 2017.



	Amount of Gains (Losses) Deferred in AOCI					Amount of Gains (Losses) Deferred in AOCI
	Three Months Ended June 30,					Six Months Ended June 30,
	2018		2017			2018		2017
Foreign exchange forward - AUD	$	1,078	$	(1,007	)	$	1,608	$	(562	)
Foreign exchange forward - CAD	—		(668		)	—		(116		)
Net gains (losses) on qualifying derivative hedges	$	1,078	$	(1,675	)	$	1,608	$	(678	)

Non-derivative Hedging Instruments of Net Investments in Foreign Operations

As at June 30, 2018 and December 31, 2017, there were borrowings of €60.0 million ($70.1 million) and €50.0 million ($60.1 million), respectively, 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. The following table presents the net gains and losses that were deferred in the CTA account, which is a component of AOCI in shareholders' equity, related to our non-derivative hedges for the three and six months ended June 30, 2018 and 2017.



	Amount of Gains (Losses) Deferred in AOCI					Amount of Gains (Losses) Deferred in AOCI
	Three Months Ended June 30,					Six Months Ended June 30,
	2018		2017			2018		2017
Net gains (losses) on qualifying non-derivative hedges	$	3,684	$	(5,370	)	$	2,448	$	(6,495	)

These amounts were offset against equivalent amounts recognized upon the translation of those subsidiaries' financial statements from their Euro-denominated functional currency into U.S. dollars. There were no ineffective portions of the net investment hedge during the three and six months ended June 30, 2018 and 2017.

Derivatives Not Designated or Not Qualifying as Hedging Instruments

From 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 the estimated fair values recorded within other assets and liabilities related to our non-qualifying foreign currency forward exchange rate hedging relationships as at June 30, 2018 and December 31, 2017.



	June 30, 2018						December 31, 2017
			Fair Value						Fair Value
	Gross Notional Amount		Assets		Liabilities		Gross Notional Amount		Assets		Liabilities
Foreign exchange forward - AUD	$	46,582	$	833	$	—	$	57,028	$	—	$	1,002
Foreign exchange forward - GBP	218,228		5,700		—		207,323		262		4,312
Foreign exchange forward - EUR	32,696		958		—		19,235		46		455
Foreign exchange forward - CAD	114,873		4,255		77		—		—		—
Total non-qualifying hedges	$	412,379	$	11,746	$	77	$	283,586	$	308	$	5,769

The following table presents the amounts of the net gains and losses included in earnings related to our non-qualifying foreign currency forward exchange rate contracts during the three and six months ended June 30, 2018 and 2017.



	Gains (Losses) on non-qualifying hedges included in net earnings
	Three Months Ended June 30,					Six Months Ended June 30,
	2018		2017			2018		2017
Foreign exchange forward - AUD	$	1,514	$	—		$	2,496	$	—
Foreign exchange forward - GBP	11,077		(611		)	4,235		(740		)
Foreign exchange forward - EUR	1,624		(354		)	1,357		(563		)
Foreign exchange forward - CAD	5,207		—			7,247		$	—
Net gains (losses) on non-qualifying hedges	$	19,422	$	(965	)	$	15,335	$	(1,303	)

Investments in Call Options on Equities

We use equity call option instruments either to obtain exposure to a particular equity instrument or for yield enhancement, in non-qualifying hedging relationships.

During the six months ended June 30, 2018 we purchased call options on equities at a cost of $10.0 million and recorded unrealized losses in net earnings of $2.5 million and $5.0 million, respectively, for the three and six months ended June 30, 2018 on the instruments. We did not have any equity derivative instruments during the six months ended June 30, 2017 or as at December 31, 2017.

Reinsurance Balances Recoverable

6 Months Ended

Jun. 30, 2018

Insurance [Abstract]

REINSURANCE BALANCES RECOVERABLE

9. REINSURANCE BALANCES RECOVERABLE

The following tables provide the total reinsurance balances recoverable as at June 30, 2018 and December 31, 2017:



	June 30, 2018
	Non-life Run-off			Atrium			StarStone			Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	994,389		$	13,442		$	176,583		$	1,184,414
IBNR	650,106			24,036			191,925			866,067
Fair value adjustments	(13,176		)	775			(1,931		)	(14,332		)
Fair value adjustments - fair value option	(169,180		)	—			—			(169,180		)
Total reinsurance reserves recoverable	1,462,139			38,253			366,577			1,866,969
Paid losses recoverable	112,153			(648		)	16,337			127,842
	$	1,574,292		$	37,605		$	382,914		$	1,994,811
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	736,919		$	37,605		$	382,914		$	1,157,438
Reinsurance balances recoverable - fair value option	837,373			—			—			837,373
Total	$	1,574,292		$	37,605		$	382,914		$	1,994,811



	December 31, 2017
	Non-life Run-off			Atrium			StarStone			Other		Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	932,284		$	7,472		$	211,650		$	16	$	1,151,422
IBNR	590,154			31,476			242,620			—		864,250
Fair value adjustments	(12,970		)	1,583			(2,253		)	—		(13,640		)
Fair value adjustments - fair value option	(131,983		)	—			—			—		(131,983		)
Total reinsurance reserves recoverable	1,377,485			40,531			452,017			16		1,870,049
Paid losses recoverable	128,253			(451		)	23,179			—		150,981
	$	1,505,738		$	40,080		$	475,196		$	16	$	2,021,030
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	963,514		$	40,080		$	475,196		$	16	$	1,478,806
Reinsurance balances recoverable - fair value option	542,224			—			—			—		542,224
Total	$	1,505,738		$	40,080		$	475,196		$	16	$	2,021,030

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 recoverables 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 7 - "Fair Value Measurements".

As at June 30, 2018 and December 31, 2017, we had reinsurance balances recoverable of $1,994.8 million and $2,021.0 million, respectively. The decrease of $26.2 million in reinsurance balances recoverable was primarily a result of KaylaRe becoming a wholly owned subsidiary during the quarter and reserve reductions in our Non-life Run-off segment and cash collections and commutations made during the six months ended June 30, 2018, partially offset by the Neon and Novae reinsurance transactions, which closed during the first quarter of 2018, as well as reserve increases in StarStone.

Top Ten Reinsurers



	June 30, 2018										December 31, 2017
	Non-life Run-off		Atrium		StarStone		Total		% of Total		Non-life Run-off		Atrium		StarStone		Other		Total		% of Total
Top ten reinsurers	$	1,212,447	$	20,095	$	221,073	$	1,453,615	72.9	%	$	1,166,057	$	22,422	$	328,257	$	—	$	1,516,736	75.0	%
Other reinsurers > $1 million	347,782		16,796		159,009		523,587		26.2	%	322,722		16,631		144,336		—		483,689		24.0	%
Other reinsurers < $1 million	14,063		714		2,832		17,609		0.9	%	16,959		1,027		2,603		16		20,605		1.0	%
Total	$	1,574,292	$	37,605	$	382,914	$	1,994,811	100.0	%	$	1,505,738	$	40,080	$	475,196	$	16	$	2,021,030	100.0	%

Seven (December 31, 2017: six) of the top ten external reinsurers, as at June 30, 2018 were rated A- or better, with the remaining three (December 31, 2017: four) being non-rated reinsurers from which $319.4 million was recoverable (December 31, 2017: $687.6 million). For the three non-rated reinsurers 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. As at June 30, 2018, reinsurance balances recoverable of $328.2 million (December 31, 2017: $320.0 million) related to Hannover Ruck SE and $308.1 million (December 31, 2017: $193.8 million) related to Lloyd’s syndicates, each of which represented 10% or more of total reinsurance balances recoverable. Lloyd’s is rated A+ by Standard & Poor’s and A by A.M. Best, and Hannover Ruck SE is rated AA- 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") as at June 30, 2018 and December 31, 2017. The provisions for bad debt all relate to the Non-life Run-off segment.



	June 30, 2018								December 31, 2017
	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	$	1,623,739	$	59,230	$	1,564,509	3.6	%	$	1,252,887	$	51,115	$	1,201,772	4.1	%
Reinsurers rated below A-, secured	398,335		—		398,335		—	%	771,097		—		771,097		—	%
Reinsurers rated below A-, unsecured	133,633		101,666		31,967		76.1	%	162,259		114,098		48,161		70.3	%
Total	$	2,155,707	$	160,896	$	1,994,811	7.5	%	$	2,186,243	$	165,213	$	2,021,030	7.6	%

12. PREMIUMS WRITTEN AND EARNED

The following table provides a summary of net premiums written and earned in our Non-life Run-off, Atrium and StarStone segments and Other activities for the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30,												Six Months Ended June 30,
	2018						2017						2018						2017
	Premiums Written			Premiums Earned			Premiums Written			Premiums Earned			Premiums Written			Premiums Earned			Premiums Written			Premiums Earned
Non-life Run-off
Gross	$	(938	)	$	23,188		$	1,222		$	4,710		$	6,442		$	36,298		$	2,205		$	6,008
Ceded	(723		)	(13,579		)	683			(1,345		)	(8,003		)	(19,511		)	(219		)	(2,567		)
Net	$	(1,661	)	$	9,609		$	1,905		$	3,365		$	(1,561	)	$	16,787		$	1,986		$	3,441
Atrium
Gross	$	41,560		$	39,795		$	34,565		$	35,822		$	91,002		$	79,469		$	80,978		$	72,042
Ceded	(6,977		)	(5,273		)	(3,238		)	(3,442		)	(14,925		)	(9,724		)	(7,732		)	(7,442		)
Net	$	34,583		$	34,522		$	31,327		$	32,380		$	76,077		$	69,745		$	73,246		$	64,600
StarStone
Gross	$	301,353		$	245,284		$	224,564		$	212,720		$	606,342		$	480,227		$	451,100		$	418,304
Ceded	(82,115		)	(61,663		)	(109,030		)	(94,169		)	(206,541		)	(169,780		)	(216,700		)	(184,345		)
Net	$	219,238		$	183,621		$	115,534		$	118,551		$	399,801		$	310,447		$	234,400		$	233,959
Other
Gross	$	975		$	980		$	582		$	1,657		$	2,012		$	2,030		$	2,082		$	3,214
Ceded	84			80			200			(382		)	37			22			(107		)	(745		)
Net	$	1,059		$	1,060		$	782		$	1,275		$	2,049		$	2,052		$	1,975		$	2,469
Total
Gross	$	342,950		$	309,247		$	260,933		$	254,909		$	705,798		$	598,024		$	536,365		$	499,568
Ceded	(89,731		)	(80,435		)	(111,385		)	(99,338		)	(229,432		)	(198,993		)	(224,758		)	(195,099		)
Total	$	253,219		$	228,812		$	149,548		$	155,571		$	476,366		$	399,031		$	311,607		$	304,469

Losses and Loss Adjustment Expenses

6 Months Ended

Jun. 30, 2018

Insurance [Abstract]

LOSSES AND LOSS ADJUSTMENT EXPENSES

10. LOSSES AND LOSS ADJUSTMENT EXPENSES

The liability for losses and loss adjustment expenses ("LAE"), also referred to as loss reserves, represents our gross estimates before reinsurance for unpaid reported losses and includes losses that have been incurred but not reported ("IBNR") for our Non-life Run-off, Atrium 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 and other non-life lines of business. Refer to Note 11 - "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, 2017 for more information on establishing the liability for losses and LAE.

The following table summarizes the liability for losses and LAE by segment as at June 30, 2018 and December 31, 2017:



	June 30, 2018											December 31, 2017
	Non-life Run-off			Atrium		StarStone			Total			Non-life Run-off			Atrium		StarStone			Total
Outstanding losses	$	4,148,834		$	84,214	$	659,239		$	4,892,287		$	3,185,703		$	78,363	$	590,977		$	3,855,043
IBNR	3,084,112			142,320		668,845			3,895,277			2,903,927			150,508		599,221			3,653,656
Fair value adjustments	(119,937		)	5,364		(475		)	(115,048		)	(125,998		)	9,547		(555		)	(117,006		)
Fair value adjustments - fair value option	(440,024		)	—		—			(440,024		)	(314,748		)	—		—			(314,748		)
ULAE	352,765			2,334		20,796			375,895			300,588			2,455		18,100			321,143
Total	$	7,025,750		$	234,232	$	1,348,405		$	8,608,387		$	5,949,472		$	240,873	$	1,207,743		$	7,398,088

Reconciliation to Consolidated Balance Sheet:
Loss and loss adjustment expenses									$	5,387,021										$	5,603,419
Loss and loss adjustment expenses, at fair value									$	3,221,366										$	1,794,669
Total									$	8,608,387										$	7,398,088

The overall increase in the liability for losses and LAE between December 31, 2017 and June 30, 2018 was primarily attributable to the assumed reinsurance agreements with Zurich Australia, Neon and Novae in our Non-life Run-off segment for which we have elected the fair value option, as described in Note 3 - "Significant New Business", and the acquisition of KaylaRe.

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30,					Six Months Ended June 30,
	2018			2017		2018			2017
Balance as at beginning of period	$	8,986,070		$	7,760,587	$	7,398,088		$	5,987,867
Less: reinsurance reserves recoverable	2,217,033			1,895,491		1,870,033			1,388,193
Less: deferred charges on retroactive reinsurance	75,111			93,605		80,192			94,551
Net balance as at beginning of period	6,693,926			5,771,491		5,447,863			4,505,123
Net incurred losses and LAE:
Current period	153,860			81,400		249,014			166,945
Prior periods	(61,041		)	(71,780)		(136,661		)	(79,433		)
Total net incurred losses and LAE	92,819			9,620		112,353			87,512
Net paid losses:
Current period	(30,474		)	(16,173)		(38,577		)	(24,892		)
Prior periods	(290,491		)	(205,222)		(641,137		)	(454,944		)
Total net paid losses	(320,965		)	(221,395)		(679,714		)	(479,836		)
Effect of exchange rate movement	(139,561		)	69,231		(81,834		)	83,736
Acquired on purchase of subsidiaries	343,806			—		343,806			—
Assumed business	—			—		1,527,551			1,432,412
Net balance as at June 30	6,670,025			5,628,947		6,670,025			5,628,947
Plus: reinsurance reserves recoverable	1,866,969			1,923,962		1,866,969			1,923,962
Plus: deferred charges on retroactive reinsurance	71,393			88,475		71,393			88,475
Balance as at June 30	$	8,608,387		$	7,641,384	$	8,608,387		$	7,641,384

The tables below provide the net incurred losses and LAE by segment for the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30, 2018												Three Months Ended June 30, 2017
	Non-life Run-off			Atrium			StarStone			Total			Non-life Run-off			Atrium			StarStone			Total
Net losses paid	$	196,311		$	19,347		$	105,307		$	320,965		$	144,412		$	12,821		$	64,162		$	221,395
Net change in case and LAE reserves	(124,364		)	(3,442		)	25,841			(101,965		)	(127,409		)	(1,121		)	8,145			(120,385		)
Net change in IBNR reserves	(157,639		)	1,855			12,742			(143,042		)	(62,311		)	(3,542		)	(6,650		)	(72,503		)
Amortization of deferred charges	3,718			—			—			3,718			5,130			—			—			5,130
Increase (reduction) in estimates of net ultimate losses	(81,974		)	17,760			143,890			79,676			(40,178		)	8,158			65,657			33,637
Reduction in provisions for bad debt	—			—			—			—			(735		)	—			—			(735		)
Increase (reduction) in provisions for unallocated LAE	(9,311		)	2			2,238			(7,071		)	(10,935		)	(56		)	287			(10,704		)
Amortization of fair value adjustments	3,918			(836		)	(101		)	2,981			678			87			(111		)	654
Changes in fair value - fair value option	17,233			—			—			17,233			(13,232		)	—			—			(13,232		)
Net incurred losses and LAE	$	(70,134	)	$	16,926		$	146,027		$	92,819		$	(64,402	)	$	8,189		$	65,833		$	9,620



	Six Months Ended June 30, 2018												Six Months Ended June 30, 2017
	Non-life Run-off			Atrium			StarStone			Total			Non-life Run-off			Atrium			StarStone			Total
Net losses paid	$	448,895		$	36,877		$	193,942		$	679,714		$	300,984		$	26,494		$	152,358		$	479,836
Net change in case and LAE reserves	(247,850		)	448			21,366			(226,036		)	(210,543		)	(527		)	(1,214		)	(212,284		)
Net change in IBNR reserves	(311,750		)	146			3,871			(307,733		)	(140,958		)	(5,346		)	(16,802		)	(163,106		)
Amortization of deferred charges	8,799			—			—			8,799			6,076			—			—			6,076
Increase (reduction) in estimates of net ultimate losses	(101,906		)	37,471			219,179			154,744			(44,441		)	20,621			134,342			110,522
Reduction in provisions for bad debt	—			—			—			—			(735		)	—			—			(735		)
Increase (reduction) in provisions for unallocated LAE	(24,263		)	2			2,430			(21,831		)	(25,258		)	(64		)	286			(25,036		)
Amortization of fair value adjustments	6,065			(3,375		)	(242		)	2,448			2,025			120			(634		)	1,511
Changes in fair value - fair value option	(23,008		)	—			—			(23,008		)	1,250			—			—			1,250
Net incurred losses and LAE	$	(143,112	)	$	34,098		$	221,367		$	112,353		$	(67,159	)	$	20,677		$	133,994		$	87,512

Non-Life Run-off Segment

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the three and six months ended June 30, 2018 and 2017 for the Non-life Run-off segment:



	Three Months Ended June 30,					Six Months Ended June 30,
	2018		2017			2018		2017
Balance as at beginning of period	$	7,517,511	$	6,478,150		$	5,949,472	$	4,716,363
Less: reinsurance reserves recoverable	1,703,481		1,504,371			1,377,485		1,000,953
Less: deferred charges on retroactive insurance	75,111		93,605			80,192		94,551
Net balance as at beginning of period	5,738,919		4,880,174			4,491,795		3,620,859
Net incurred losses and LAE:
Current period	5,113		461			5,459		1,175
Prior periods	(75,247)		(64,863		)	(148,571)		(68,334		)
Total net incurred losses and LAE	(70,134)		(64,402		)	(143,112)		(67,159		)
Net paid losses:
Current period	(590)		(130		)	(591)		(371		)
Prior periods	(195,721)		(144,282		)	(448,304)		(300,613		)
Total net paid losses	(196,311)		(144,412		)	(448,895)		(300,984		)
Effect of exchange rate movement	(131,081)		56,887			(75,678)		74,512
Acquired on purchase of subsidiaries	150,825		—			150,825		—
Assumed business	—		—			1,517,283		1,401,019
Net balance as at June 30	5,492,218		4,728,247			5,492,218		4,728,247
Plus: reinsurance reserves recoverable	1,462,139		1,500,557			1,462,139		1,500,557
Plus: deferred charges on retroactive reinsurance	71,393		88,475			71,393		88,475
Balance as at June 30	$	7,025,750	$	6,317,279		$	7,025,750	$	6,317,279

Net incurred losses and LAE in the Non-life Run-off segment for the three months ended June 30, 2018 and 2017 were as follows:



	Three Months Ended June 30,
	2018								2017
	Prior Period			Current Period		Total			Prior Period			Current Period			Total
Net losses paid	$	195,721		$	590	$	196,311		$	144,282		$	130		$	144,412
Net change in case and LAE reserves	(125,416		)	1,052		(124,364		)	(127,393		)	(16		)	(127,409		)
Net change in IBNR reserves	(161,110		)	3,471		(157,639		)	(62,604		)	293			(62,311		)
Amortization of deferred charges	3,718			—		3,718			5,130			—			5,130
Increase (reduction) in estimates of net ultimate losses	(87,087		)	5,113		(81,974		)	(40,585		)	407			(40,178		)
Reduction in provisions for bad debt	—			—		—			(735		)	—			(735		)
Increase (reduction) in provisions for unallocated LAE	(9,311		)	—		(9,311		)	(10,989		)	54			(10,935		)
Amortization of fair value adjustments	3,918			—		3,918			678			—			678
Changes in fair value - fair value option	17,233			—		17,233			(13,232		)	—			(13,232		)
Net incurred losses and LAE	$	(75,247	)	$	5,113	$	(70,134	)	$	(64,863	)	$	461		$	(64,402	)

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 June 30, 2018

The reduction in net incurred losses and LAE for the three months ended June 30, 2018 of $70.1 million included net incurred losses and LAE of $5.1 million related to current period net earned premium. Excluding current period net incurred losses and LAE of $5.1 million, the reduction in net incurred losses and LAE liabilities relating to prior periods was $75.2 million, which was attributable to a reduction in estimates of net ultimate losses of $87.1 million, a reduction in provisions for unallocated LAE of $9.3 million relating to 2018 run-off activity and a change in fair value of $17.2 million related to our assumed retroactive reinsurance agreements for which we have elected the fair value option, partially offset by amortization of fair value adjustments over the estimated payout period relating to companies acquired of $3.9 million. The reduction in estimates of net ultimate losses of $87.1 million for the three months ended June 30, 2018 included a net reduction in case and IBNR reserves of $286.5 million, partially offset by net losses paid of $195.7 million and the amortization of the deferred charges of $3.7 million.

Three Months Ended June 30, 2017

The reduction in net incurred losses and LAE for the three months ended June 30, 2017 of $64.4 million included net incurred losses and LAE of $0.5 million related to current period net earned premium, primarily for the run-off business acquired with Sussex. Excluding current period net incurred losses and LAE of $0.5 million, the reduction in net incurred losses and LAE liabilities relating to prior periods was $64.9 million, which was attributable to a reduction in estimates of net ultimate losses of $40.6 million, and a reduction in provisions for unallocated LAE of $11.0 million, relating to 2017 run-off activity and a change in fair value of $13.2 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 $0.7 million. The reduction in estimates of net ultimate losses of $40.6 million for the three months ended June 30, 2017 included a net change in case and IBNR reserves of $190.0 million, partially offset by net losses paid of $144.3 million and the amortization of the deferred charges of $5.1 million.

Net incurred losses and LAE in the Non-life Run-off segment for the six months ended June 30, 2018 and 2017 were as follows:



	Six Months Ended June 30,
	2018								2017
	Prior Period			Current Period		Total			Prior Period			Current Period			Total
Net losses paid	$	448,304		$	591	$	448,895		$	300,613		$	371		$	300,984
Net change in case and LAE reserves	(248,908		)	1,058		(247,850		)	(210,527		)	(16		)	(210,543		)
Net change in IBNR reserves	(315,560		)	3,810		(311,750		)	(141,682		)	724			(140,958		)
Amortization of deferred charges	8,799			—		8,799			6,076			—			6,076
Increase (reduction) in estimates of net ultimate losses	(107,365		)	5,459		(101,906		)	(45,520		)	1,079			(44,441		)
Reduction in provisions for bad debt	—			—		—			(735		)	—			(735		)
Increase (reduction) in provisions for unallocated LAE	(24,263		)	—		(24,263		)	(25,354		)	96			(25,258		)
Amortization of fair value adjustments	6,065			—		6,065			2,025			—			2,025
Changes in fair value - fair value option	(23,008		)	—		(23,008		)	1,250			—			1,250
Net incurred losses and LAE	$	(148,571	)	$	5,459	$	(143,112	)	$	(68,334	)	$	1,175		$	(67,159	)

Six Months Ended June 30, 2018

The reduction in net incurred losses and LAE for the six months ended June 30, 2018 of $143.1 million included net incurred losses and LAE of $5.5 million related to current period net earned premium. Excluding current period net incurred losses and LAE of $5.5 million, net incurred losses and LAE liabilities relating to prior periods were reduced by $148.6 million, which was attributable to a reduction in estimates of net ultimate losses of $107.4 million, a reduction in provisions for unallocated LAE of $24.3 million and a change in fair value of $23.0 million related to our assumed retroactive reinsurance agreements for which we have elected the fair value option, partially offset by amortization of fair value adjustments over the estimated payout period relating to companies acquired of $6.1 million. The reduction in estimates of net ultimate losses for the six months ended June 30, 2018 included a net change in case and IBNR reserves of $564.5 million, partially offset by net losses of $448.3 million and amortization of the deferred charges of $8.8 million.

Six Months Ended June 30, 2017

The reduction in net incurred losses and LAE for the six months ended June 30, 2017 of $67.2 million included net incurred losses and LAE of $1.2 million related to current period net earned premium, related to the run-off business acquired with Sussex. Excluding current period net incurred losses and LAE of $1.2 million, net incurred losses and LAE liabilities relating to prior periods were reduced by $68.3 million, which was attributable to a reduction in estimates of net ultimate losses of $45.5 million, a reduction in provisions for bad debt of $0.7 million and a reduction in provisions for unallocated LAE of $25.4 million, partially offset by amortization of fair value adjustments over the estimated payout period relating to companies acquired amounting to $2.0 million and an increase in fair value of $1.3 million related to our assumed retroactive reinsurance agreements with for which we have elected the fair value option. The reduction in estimates of net ultimate losses for the six months ended June 30, 2017 included a net change in case and IBNR reserves of $352.2 million. The reduction of estimates in net ultimate losses for the six months ended June 30, 2017 was reduced by amortization of the deferred charges of $6.1 million.

Atrium

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the three and six months ended June 30, 2018 and 2017 for the Atrium segment:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Balance as at beginning of period	$	240,795		$	212,123		$	240,873		$	212,122
Less: reinsurance reserves recoverable	40,025			30,625			40,531			30,009
Net balance as at beginning of period	200,770			181,498			200,342			182,113
Net incurred losses and LAE:
Current period	19,175			14,858			36,481			29,279
Prior periods	(2,249		)	(6,669		)	(2,383		)	(8,602		)
Total net incurred losses and LAE	16,926			8,189			34,098			20,677
Net paid losses:
Current period	(10,465		)	(5,398		)	(17,619		)	(9,660		)
Prior periods	(8,882		)	(7,423		)	(19,258		)	(16,834		)
Total net paid losses	(19,347		)	(12,821		)	(36,877		)	(26,494		)
Effect of exchange rate movement	(2,370		)	2,031			(1,584		)	2,601
Net balance as at June 30	195,979			178,897			195,979			178,897
Plus: reinsurance reserves recoverable	38,253			29,749			38,253			29,749
Balance as at June 30	$	234,232		$	208,646		$	234,232		$	208,646

Net incurred losses and LAE in the Atrium segment for the three and six months ended June 30, 2018 and 2017 were as follows:



	Three Months Ended June 30,
	2018						2017
	Prior Period		Current Period		Total		Prior Period		Current Period		Total
Net losses paid	8,882		10,465		19,347		7,423		5,398		12,821
Net change in case and LAE reserves	(3,169	)	(273	)	(3,442	)	(2,007	)	886		(1,121	)
Net change in IBNR reserves	(7,128	)	8,983		1,855		(12,221	)	8,679		(3,542	)
Increase (reduction) in estimates of net ultimate losses	(1,415	)	19,175		17,760		(6,805	)	14,963		8,158
Increase (reduction) in provisions for unallocated LAE	2		—		2		49		(105	)	(56	)
Amortization of fair value adjustments	(836	)	—		(836	)	87		—		87
Net incurred losses and LAE	(2,249	)	19,175		16,926		(6,669	)	14,858		8,189



	Six Months Ended June 30,
	2018							2017
	Prior Period			Current Period		Total		Prior Period			Current Period		Total
Net losses paid	$	19,258		$	17,619	$	36,877	$	16,834		$	9,660	$	26,494
Net change in case and LAE reserves	(5,553)			6,001		448		(5,123)			4,596		(527)
Net change in IBNR reserves	(12,715)			12,861		146		(20,358)			15,012		(5,346)
Increase (reduction) in estimates of net ultimate losses	990			36,481		37,471		(8,647)			29,268		20,621
Increase (reduction) in provisions for unallocated LAE	2			—		2		(75)			11		(64)
Amortization of fair value adjustments	(3,375)			—		(3,375)		120			—		120
Net incurred losses and LAE	$	(2,383	)	$	36,481	$	34,098	$	(8,602	)	$	29,279	$	20,677

StarStone

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the three and six months ended June 30, 2018 and 2017 for our StarStone segment:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Balance as at beginning of period	$	1,227,764		$	1,070,314		$	1,207,743		$	1,059,382
Less: reinsurance reserves recoverable	473,527			360,495			452,017			357,231
Net balance as at beginning of period	754,237			709,819			755,726			702,151
Net incurred losses and LAE:
Current period	129,572			66,081			207,074			136,491
Prior periods	16,455			(248		)	14,293			(2,497		)
Total net incurred losses and LAE	146,027			65,833			221,367			133,994
Net paid losses:
Current period	(19,419)			(10,645		)	(20,367		)	(14,861		)
Prior periods	(85,888)			(53,517		)	(173,575		)	(137,497		)
Total net paid losses	(105,307)			(64,162		)	(193,942		)	(152,358		)
Effect of exchange rate movement	(6,110		)	10,313			(4,572		)	6,623
Acquired on purchase of subsidiaries	192,981			—			192,981			—
Assumed business	—			—			10,268			31,393
Net balance as at June 30	981,828			721,803			981,828			721,803
Plus: reinsurance reserves recoverable	366,577			393,656			366,577			393,656
Balance as at June 30	$	1,348,405		$	1,115,459		$	1,348,405		$	1,115,459

Net incurred losses and LAE in the StarStone segment for the three and six months ended June 30, 2018 and 2017 were as follows:



	Three Months Ended June 30,
	2018								2017
	Prior Period			Current Period		Total			Prior Period			Current Period		Total
Net losses paid	$	85,888		$	19,419	$	105,307		$	53,517		$	10,645	$	64,162
Net change in case and LAE reserves	(21,405		)	47,246		25,841			(16,621		)	24,766		8,145
Net change in IBNR reserves	(46,738		)	59,480		12,742			(35,828		)	29,178		(6,650		)
Increase in estimates of net ultimate losses	17,745			126,145		143,890			1,068			64,589		65,657
Increase (reduction) in provisions for unallocated LAE	(1,189		)	3,427		2,238			(1,205		)	1,492		287
Amortization of fair value adjustments	(101		)	—		(101		)	(111		)	—		(111		)
Net incurred losses and LAE	$	16,455		$	129,572	$	146,027		$	(248	)	$	66,081	$	65,833



	Six Months Ended June 30,
	2018								2017
	Prior Period			Current Period		Total			Prior Period			Current Period		Total
Net losses paid	$	173,575		$	20,367	$	193,942		$	137,497		$	14,861	$	152,358
Net change in case and LAE reserves	(35,622		)	56,988		21,366			(41,464		)	40,250		(1,214		)
Net change in IBNR reserves	(120,128		)	123,999		3,871			(94,765		)	77,963		(16,802		)
Increase in estimates of net ultimate losses	17,825			201,354		219,179			1,268			133,074		134,342
Increase (reduction) in provisions for unallocated LAE	(3,290		)	5,720		2,430			(3,131		)	3,417		286
Amortization of fair value adjustments	(242		)	—		(242		)	(634		)	—		(634		)
Net incurred losses and LAE	$	14,293		$	207,074	$	221,367		$	(2,497	)	$	136,491	$	133,994

11. 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 at June 30, 2018 and December 31, 2017 were $109.0 million and $117.2 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, 2017 for a description of the assumptions used and the process for establishing our assumptions and estimates.

Policy Benefits for Life Contracts

6 Months Ended

Jun. 30, 2018

Insurance [Abstract]

POLICY BENEFITS FOR LIFE CONTRACTS

10. LOSSES AND LOSS ADJUSTMENT EXPENSES

The following table summarizes the liability for losses and LAE by segment as at June 30, 2018 and December 31, 2017:



	June 30, 2018											December 31, 2017
	Non-life Run-off			Atrium		StarStone			Total			Non-life Run-off			Atrium		StarStone			Total
Outstanding losses	$	4,148,834		$	84,214	$	659,239		$	4,892,287		$	3,185,703		$	78,363	$	590,977		$	3,855,043
IBNR	3,084,112			142,320		668,845			3,895,277			2,903,927			150,508		599,221			3,653,656
Fair value adjustments	(119,937		)	5,364		(475		)	(115,048		)	(125,998		)	9,547		(555		)	(117,006		)
Fair value adjustments - fair value option	(440,024		)	—		—			(440,024		)	(314,748		)	—		—			(314,748		)
ULAE	352,765			2,334		20,796			375,895			300,588			2,455		18,100			321,143
Total	$	7,025,750		$	234,232	$	1,348,405		$	8,608,387		$	5,949,472		$	240,873	$	1,207,743		$	7,398,088

Reconciliation to Consolidated Balance Sheet:
Loss and loss adjustment expenses									$	5,387,021										$	5,603,419
Loss and loss adjustment expenses, at fair value									$	3,221,366										$	1,794,669
Total									$	8,608,387										$	7,398,088

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30,					Six Months Ended June 30,
	2018			2017		2018			2017
Balance as at beginning of period	$	8,986,070		$	7,760,587	$	7,398,088		$	5,987,867
Less: reinsurance reserves recoverable	2,217,033			1,895,491		1,870,033			1,388,193
Less: deferred charges on retroactive reinsurance	75,111			93,605		80,192			94,551
Net balance as at beginning of period	6,693,926			5,771,491		5,447,863			4,505,123
Net incurred losses and LAE:
Current period	153,860			81,400		249,014			166,945
Prior periods	(61,041		)	(71,780)		(136,661		)	(79,433		)
Total net incurred losses and LAE	92,819			9,620		112,353			87,512
Net paid losses:
Current period	(30,474		)	(16,173)		(38,577		)	(24,892		)
Prior periods	(290,491		)	(205,222)		(641,137		)	(454,944		)
Total net paid losses	(320,965		)	(221,395)		(679,714		)	(479,836		)
Effect of exchange rate movement	(139,561		)	69,231		(81,834		)	83,736
Acquired on purchase of subsidiaries	343,806			—		343,806			—
Assumed business	—			—		1,527,551			1,432,412
Net balance as at June 30	6,670,025			5,628,947		6,670,025			5,628,947
Plus: reinsurance reserves recoverable	1,866,969			1,923,962		1,866,969			1,923,962
Plus: deferred charges on retroactive reinsurance	71,393			88,475		71,393			88,475
Balance as at June 30	$	8,608,387		$	7,641,384	$	8,608,387		$	7,641,384

The tables below provide the net incurred losses and LAE by segment for the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30, 2018												Three Months Ended June 30, 2017
	Non-life Run-off			Atrium			StarStone			Total			Non-life Run-off			Atrium			StarStone			Total
Net losses paid	$	196,311		$	19,347		$	105,307		$	320,965		$	144,412		$	12,821		$	64,162		$	221,395
Net change in case and LAE reserves	(124,364		)	(3,442		)	25,841			(101,965		)	(127,409		)	(1,121		)	8,145			(120,385		)
Net change in IBNR reserves	(157,639		)	1,855			12,742			(143,042		)	(62,311		)	(3,542		)	(6,650		)	(72,503		)
Amortization of deferred charges	3,718			—			—			3,718			5,130			—			—			5,130
Increase (reduction) in estimates of net ultimate losses	(81,974		)	17,760			143,890			79,676			(40,178		)	8,158			65,657			33,637
Reduction in provisions for bad debt	—			—			—			—			(735		)	—			—			(735		)
Increase (reduction) in provisions for unallocated LAE	(9,311		)	2			2,238			(7,071		)	(10,935		)	(56		)	287			(10,704		)
Amortization of fair value adjustments	3,918			(836		)	(101		)	2,981			678			87			(111		)	654
Changes in fair value - fair value option	17,233			—			—			17,233			(13,232		)	—			—			(13,232		)
Net incurred losses and LAE	$	(70,134	)	$	16,926		$	146,027		$	92,819		$	(64,402	)	$	8,189		$	65,833		$	9,620



	Six Months Ended June 30, 2018												Six Months Ended June 30, 2017
	Non-life Run-off			Atrium			StarStone			Total			Non-life Run-off			Atrium			StarStone			Total
Net losses paid	$	448,895		$	36,877		$	193,942		$	679,714		$	300,984		$	26,494		$	152,358		$	479,836
Net change in case and LAE reserves	(247,850		)	448			21,366			(226,036		)	(210,543		)	(527		)	(1,214		)	(212,284		)
Net change in IBNR reserves	(311,750		)	146			3,871			(307,733		)	(140,958		)	(5,346		)	(16,802		)	(163,106		)
Amortization of deferred charges	8,799			—			—			8,799			6,076			—			—			6,076
Increase (reduction) in estimates of net ultimate losses	(101,906		)	37,471			219,179			154,744			(44,441		)	20,621			134,342			110,522
Reduction in provisions for bad debt	—			—			—			—			(735		)	—			—			(735		)
Increase (reduction) in provisions for unallocated LAE	(24,263		)	2			2,430			(21,831		)	(25,258		)	(64		)	286			(25,036		)
Amortization of fair value adjustments	6,065			(3,375		)	(242		)	2,448			2,025			120			(634		)	1,511
Changes in fair value - fair value option	(23,008		)	—			—			(23,008		)	1,250			—			—			1,250
Net incurred losses and LAE	$	(143,112	)	$	34,098		$	221,367		$	112,353		$	(67,159	)	$	20,677		$	133,994		$	87,512

Non-Life Run-off Segment

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the three and six months ended June 30, 2018 and 2017 for the Non-life Run-off segment:



	Three Months Ended June 30,					Six Months Ended June 30,
	2018		2017			2018		2017
Balance as at beginning of period	$	7,517,511	$	6,478,150		$	5,949,472	$	4,716,363
Less: reinsurance reserves recoverable	1,703,481		1,504,371			1,377,485		1,000,953
Less: deferred charges on retroactive insurance	75,111		93,605			80,192		94,551
Net balance as at beginning of period	5,738,919		4,880,174			4,491,795		3,620,859
Net incurred losses and LAE:
Current period	5,113		461			5,459		1,175
Prior periods	(75,247)		(64,863		)	(148,571)		(68,334		)
Total net incurred losses and LAE	(70,134)		(64,402		)	(143,112)		(67,159		)
Net paid losses:
Current period	(590)		(130		)	(591)		(371		)
Prior periods	(195,721)		(144,282		)	(448,304)		(300,613		)
Total net paid losses	(196,311)		(144,412		)	(448,895)		(300,984		)
Effect of exchange rate movement	(131,081)		56,887			(75,678)		74,512
Acquired on purchase of subsidiaries	150,825		—			150,825		—
Assumed business	—		—			1,517,283		1,401,019
Net balance as at June 30	5,492,218		4,728,247			5,492,218		4,728,247
Plus: reinsurance reserves recoverable	1,462,139		1,500,557			1,462,139		1,500,557
Plus: deferred charges on retroactive reinsurance	71,393		88,475			71,393		88,475
Balance as at June 30	$	7,025,750	$	6,317,279		$	7,025,750	$	6,317,279

Net incurred losses and LAE in the Non-life Run-off segment for the three months ended June 30, 2018 and 2017 were as follows:



	Three Months Ended June 30,
	2018								2017
	Prior Period			Current Period		Total			Prior Period			Current Period			Total
Net losses paid	$	195,721		$	590	$	196,311		$	144,282		$	130		$	144,412
Net change in case and LAE reserves	(125,416		)	1,052		(124,364		)	(127,393		)	(16		)	(127,409		)
Net change in IBNR reserves	(161,110		)	3,471		(157,639		)	(62,604		)	293			(62,311		)
Amortization of deferred charges	3,718			—		3,718			5,130			—			5,130
Increase (reduction) in estimates of net ultimate losses	(87,087		)	5,113		(81,974		)	(40,585		)	407			(40,178		)
Reduction in provisions for bad debt	—			—		—			(735		)	—			(735		)
Increase (reduction) in provisions for unallocated LAE	(9,311		)	—		(9,311		)	(10,989		)	54			(10,935		)
Amortization of fair value adjustments	3,918			—		3,918			678			—			678
Changes in fair value - fair value option	17,233			—		17,233			(13,232		)	—			(13,232		)
Net incurred losses and LAE	$	(75,247	)	$	5,113	$	(70,134	)	$	(64,863	)	$	461		$	(64,402	)

Three Months Ended June 30, 2018

Three Months Ended June 30, 2017

Net incurred losses and LAE in the Non-life Run-off segment for the six months ended June 30, 2018 and 2017 were as follows:



	Six Months Ended June 30,
	2018								2017
	Prior Period			Current Period		Total			Prior Period			Current Period			Total
Net losses paid	$	448,304		$	591	$	448,895		$	300,613		$	371		$	300,984
Net change in case and LAE reserves	(248,908		)	1,058		(247,850		)	(210,527		)	(16		)	(210,543		)
Net change in IBNR reserves	(315,560		)	3,810		(311,750		)	(141,682		)	724			(140,958		)
Amortization of deferred charges	8,799			—		8,799			6,076			—			6,076
Increase (reduction) in estimates of net ultimate losses	(107,365		)	5,459		(101,906		)	(45,520		)	1,079			(44,441		)
Reduction in provisions for bad debt	—			—		—			(735		)	—			(735		)
Increase (reduction) in provisions for unallocated LAE	(24,263		)	—		(24,263		)	(25,354		)	96			(25,258		)
Amortization of fair value adjustments	6,065			—		6,065			2,025			—			2,025
Changes in fair value - fair value option	(23,008		)	—		(23,008		)	1,250			—			1,250
Net incurred losses and LAE	$	(148,571	)	$	5,459	$	(143,112	)	$	(68,334	)	$	1,175		$	(67,159	)

Six Months Ended June 30, 2018

Six Months Ended June 30, 2017

Atrium

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the three and six months ended June 30, 2018 and 2017 for the Atrium segment:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Balance as at beginning of period	$	240,795		$	212,123		$	240,873		$	212,122
Less: reinsurance reserves recoverable	40,025			30,625			40,531			30,009
Net balance as at beginning of period	200,770			181,498			200,342			182,113
Net incurred losses and LAE:
Current period	19,175			14,858			36,481			29,279
Prior periods	(2,249		)	(6,669		)	(2,383		)	(8,602		)
Total net incurred losses and LAE	16,926			8,189			34,098			20,677
Net paid losses:
Current period	(10,465		)	(5,398		)	(17,619		)	(9,660		)
Prior periods	(8,882		)	(7,423		)	(19,258		)	(16,834		)
Total net paid losses	(19,347		)	(12,821		)	(36,877		)	(26,494		)
Effect of exchange rate movement	(2,370		)	2,031			(1,584		)	2,601
Net balance as at June 30	195,979			178,897			195,979			178,897
Plus: reinsurance reserves recoverable	38,253			29,749			38,253			29,749
Balance as at June 30	$	234,232		$	208,646		$	234,232		$	208,646

Net incurred losses and LAE in the Atrium segment for the three and six months ended June 30, 2018 and 2017 were as follows:



	Three Months Ended June 30,
	2018						2017
	Prior Period		Current Period		Total		Prior Period		Current Period		Total
Net losses paid	8,882		10,465		19,347		7,423		5,398		12,821
Net change in case and LAE reserves	(3,169	)	(273	)	(3,442	)	(2,007	)	886		(1,121	)
Net change in IBNR reserves	(7,128	)	8,983		1,855		(12,221	)	8,679		(3,542	)
Increase (reduction) in estimates of net ultimate losses	(1,415	)	19,175		17,760		(6,805	)	14,963		8,158
Increase (reduction) in provisions for unallocated LAE	2		—		2		49		(105	)	(56	)
Amortization of fair value adjustments	(836	)	—		(836	)	87		—		87
Net incurred losses and LAE	(2,249	)	19,175		16,926		(6,669	)	14,858		8,189



	Six Months Ended June 30,
	2018							2017
	Prior Period			Current Period		Total		Prior Period			Current Period		Total
Net losses paid	$	19,258		$	17,619	$	36,877	$	16,834		$	9,660	$	26,494
Net change in case and LAE reserves	(5,553)			6,001		448		(5,123)			4,596		(527)
Net change in IBNR reserves	(12,715)			12,861		146		(20,358)			15,012		(5,346)
Increase (reduction) in estimates of net ultimate losses	990			36,481		37,471		(8,647)			29,268		20,621
Increase (reduction) in provisions for unallocated LAE	2			—		2		(75)			11		(64)
Amortization of fair value adjustments	(3,375)			—		(3,375)		120			—		120
Net incurred losses and LAE	$	(2,383	)	$	36,481	$	34,098	$	(8,602	)	$	29,279	$	20,677

StarStone

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the three and six months ended June 30, 2018 and 2017 for our StarStone segment:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Balance as at beginning of period	$	1,227,764		$	1,070,314		$	1,207,743		$	1,059,382
Less: reinsurance reserves recoverable	473,527			360,495			452,017			357,231
Net balance as at beginning of period	754,237			709,819			755,726			702,151
Net incurred losses and LAE:
Current period	129,572			66,081			207,074			136,491
Prior periods	16,455			(248		)	14,293			(2,497		)
Total net incurred losses and LAE	146,027			65,833			221,367			133,994
Net paid losses:
Current period	(19,419)			(10,645		)	(20,367		)	(14,861		)
Prior periods	(85,888)			(53,517		)	(173,575		)	(137,497		)
Total net paid losses	(105,307)			(64,162		)	(193,942		)	(152,358		)
Effect of exchange rate movement	(6,110		)	10,313			(4,572		)	6,623
Acquired on purchase of subsidiaries	192,981			—			192,981			—
Assumed business	—			—			10,268			31,393
Net balance as at June 30	981,828			721,803			981,828			721,803
Plus: reinsurance reserves recoverable	366,577			393,656			366,577			393,656
Balance as at June 30	$	1,348,405		$	1,115,459		$	1,348,405		$	1,115,459

Net incurred losses and LAE in the StarStone segment for the three and six months ended June 30, 2018 and 2017 were as follows:



	Three Months Ended June 30,
	2018								2017
	Prior Period			Current Period		Total			Prior Period			Current Period		Total
Net losses paid	$	85,888		$	19,419	$	105,307		$	53,517		$	10,645	$	64,162
Net change in case and LAE reserves	(21,405		)	47,246		25,841			(16,621		)	24,766		8,145
Net change in IBNR reserves	(46,738		)	59,480		12,742			(35,828		)	29,178		(6,650		)
Increase in estimates of net ultimate losses	17,745			126,145		143,890			1,068			64,589		65,657
Increase (reduction) in provisions for unallocated LAE	(1,189		)	3,427		2,238			(1,205		)	1,492		287
Amortization of fair value adjustments	(101		)	—		(101		)	(111		)	—		(111		)
Net incurred losses and LAE	$	16,455		$	129,572	$	146,027		$	(248	)	$	66,081	$	65,833



	Six Months Ended June 30,
	2018								2017
	Prior Period			Current Period		Total			Prior Period			Current Period		Total
Net losses paid	$	173,575		$	20,367	$	193,942		$	137,497		$	14,861	$	152,358
Net change in case and LAE reserves	(35,622		)	56,988		21,366			(41,464		)	40,250		(1,214		)
Net change in IBNR reserves	(120,128		)	123,999		3,871			(94,765		)	77,963		(16,802		)
Increase in estimates of net ultimate losses	17,825			201,354		219,179			1,268			133,074		134,342
Increase (reduction) in provisions for unallocated LAE	(3,290		)	5,720		2,430			(3,131		)	3,417		286
Amortization of fair value adjustments	(242		)	—		(242		)	(634		)	—		(634		)
Net incurred losses and LAE	$	14,293		$	207,074	$	221,367		$	(2,497	)	$	136,491	$	133,994

11. POLICY BENEFITS FOR LIFE CONTRACTS

Premiums Written and Earned

6 Months Ended

Jun. 30, 2018

Insurance [Abstract]

PREMIUMS WRITTEN AND EARNED

9. REINSURANCE BALANCES RECOVERABLE

The following tables provide the total reinsurance balances recoverable as at June 30, 2018 and December 31, 2017:



	June 30, 2018
	Non-life Run-off			Atrium			StarStone			Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	994,389		$	13,442		$	176,583		$	1,184,414
IBNR	650,106			24,036			191,925			866,067
Fair value adjustments	(13,176		)	775			(1,931		)	(14,332		)
Fair value adjustments - fair value option	(169,180		)	—			—			(169,180		)
Total reinsurance reserves recoverable	1,462,139			38,253			366,577			1,866,969
Paid losses recoverable	112,153			(648		)	16,337			127,842
	$	1,574,292		$	37,605		$	382,914		$	1,994,811
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	736,919		$	37,605		$	382,914		$	1,157,438
Reinsurance balances recoverable - fair value option	837,373			—			—			837,373
Total	$	1,574,292		$	37,605		$	382,914		$	1,994,811



	December 31, 2017
	Non-life Run-off			Atrium			StarStone			Other		Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	932,284		$	7,472		$	211,650		$	16	$	1,151,422
IBNR	590,154			31,476			242,620			—		864,250
Fair value adjustments	(12,970		)	1,583			(2,253		)	—		(13,640		)
Fair value adjustments - fair value option	(131,983		)	—			—			—		(131,983		)
Total reinsurance reserves recoverable	1,377,485			40,531			452,017			16		1,870,049
Paid losses recoverable	128,253			(451		)	23,179			—		150,981
	$	1,505,738		$	40,080		$	475,196		$	16	$	2,021,030
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	963,514		$	40,080		$	475,196		$	16	$	1,478,806
Reinsurance balances recoverable - fair value option	542,224			—			—			—		542,224
Total	$	1,505,738		$	40,080		$	475,196		$	16	$	2,021,030

Top Ten Reinsurers



	June 30, 2018										December 31, 2017
	Non-life Run-off		Atrium		StarStone		Total		% of Total		Non-life Run-off		Atrium		StarStone		Other		Total		% of Total
Top ten reinsurers	$	1,212,447	$	20,095	$	221,073	$	1,453,615	72.9	%	$	1,166,057	$	22,422	$	328,257	$	—	$	1,516,736	75.0	%
Other reinsurers > $1 million	347,782		16,796		159,009		523,587		26.2	%	322,722		16,631		144,336		—		483,689		24.0	%
Other reinsurers < $1 million	14,063		714		2,832		17,609		0.9	%	16,959		1,027		2,603		16		20,605		1.0	%
Total	$	1,574,292	$	37,605	$	382,914	$	1,994,811	100.0	%	$	1,505,738	$	40,080	$	475,196	$	16	$	2,021,030	100.0	%

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.



	June 30, 2018								December 31, 2017
	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	$	1,623,739	$	59,230	$	1,564,509	3.6	%	$	1,252,887	$	51,115	$	1,201,772	4.1	%
Reinsurers rated below A-, secured	398,335		—		398,335		—	%	771,097		—		771,097		—	%
Reinsurers rated below A-, unsecured	133,633		101,666		31,967		76.1	%	162,259		114,098		48,161		70.3	%
Total	$	2,155,707	$	160,896	$	1,994,811	7.5	%	$	2,186,243	$	165,213	$	2,021,030	7.6	%

12. PREMIUMS WRITTEN AND EARNED



	Three Months Ended June 30,												Six Months Ended June 30,
	2018						2017						2018						2017
	Premiums Written			Premiums Earned			Premiums Written			Premiums Earned			Premiums Written			Premiums Earned			Premiums Written			Premiums Earned
Non-life Run-off
Gross	$	(938	)	$	23,188		$	1,222		$	4,710		$	6,442		$	36,298		$	2,205		$	6,008
Ceded	(723		)	(13,579		)	683			(1,345		)	(8,003		)	(19,511		)	(219		)	(2,567		)
Net	$	(1,661	)	$	9,609		$	1,905		$	3,365		$	(1,561	)	$	16,787		$	1,986		$	3,441
Atrium
Gross	$	41,560		$	39,795		$	34,565		$	35,822		$	91,002		$	79,469		$	80,978		$	72,042
Ceded	(6,977		)	(5,273		)	(3,238		)	(3,442		)	(14,925		)	(9,724		)	(7,732		)	(7,442		)
Net	$	34,583		$	34,522		$	31,327		$	32,380		$	76,077		$	69,745		$	73,246		$	64,600
StarStone
Gross	$	301,353		$	245,284		$	224,564		$	212,720		$	606,342		$	480,227		$	451,100		$	418,304
Ceded	(82,115		)	(61,663		)	(109,030		)	(94,169		)	(206,541		)	(169,780		)	(216,700		)	(184,345		)
Net	$	219,238		$	183,621		$	115,534		$	118,551		$	399,801		$	310,447		$	234,400		$	233,959
Other
Gross	$	975		$	980		$	582		$	1,657		$	2,012		$	2,030		$	2,082		$	3,214
Ceded	84			80			200			(382		)	37			22			(107		)	(745		)
Net	$	1,059		$	1,060		$	782		$	1,275		$	2,049		$	2,052		$	1,975		$	2,469
Total
Gross	$	342,950		$	309,247		$	260,933		$	254,909		$	705,798		$	598,024		$	536,365		$	499,568
Ceded	(89,731		)	(80,435		)	(111,385		)	(99,338		)	(229,432		)	(198,993		)	(224,758		)	(195,099		)
Total	$	253,219		$	228,812		$	149,548		$	155,571		$	476,366		$	399,031		$	311,607		$	304,469

Goodwill and Intangible Assets

6 Months Ended

Jun. 30, 2018

Goodwill, Intangible Assets, Intangible Assets Arising from Insurance Contracts Acquired in Business Combination, and Deferred Charges Disclosure [Abstract]

GOODWILL AND INTANGIBLE ASSETS

13. GOODWILL AND INTANGIBLE ASSETS

The following table presents a reconciliation of the beginning and ending goodwill, intangible assets and the deferred charges during the six months ended June 30, 2018:



	Goodwill		Intangible assets with a definite life - Other			Intangible assets with an indefinite life		Total			Intangible assets with a definite life - FVA			Other assets - Deferred Charges
Balance as at January 1, 2018	$	73,071	$	20,487		$	87,031	$	180,589		$	140,393		$	80,192
Acquired during the period	41,736		—			—		41,736			—			—
Amortization	—		(2,460		)	—		(2,460		)	(2,786		)	(8,799		)
Balance as at June 30, 2018	$	114,807	$	18,027		$	87,031	$	219,865		$	137,607		$	71,393

Refer to Note 2 - "Acquisitions" for further details on the goodwill acquired during the period. Refer to Note 14 - "Goodwill, Intangible assets and Deferred Charges" to the consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2017 for more information on goodwill, intangible assets and the deferred charges.

Intangible asset amortization for the three and six months ended June 30, 2018 was $4.5 million and $5.2 million, respectively, compared to $0.7 million and $2.2 million for the comparative periods in 2017.

The gross carrying value, accumulated amortization and net carrying value of intangible assets by type and the deferred charge as at June 30, 2018 and December 31, 2017 were as follows:



	June 30, 2018									December 31, 2017
	Gross Carrying Value			Accumulated Amortization			Net Carrying Value			Gross Carrying Value			Accumulated Amortization			Net Carrying Value
Intangible assets with a definite life:
Fair value adjustments:
Losses and LAE liabilities	$	462,455		$	(347,407	)	$	115,048		$	462,455		$	(345,449	)	$	117,006
Reinsurance balances recoverable	(179,219		)	164,887			(14,332		)	(179,219		)	165,579			(13,640		)
Other Assets	(48,840		)	706			(48,134		)	(48,840		)	440			(48,400		)
Other Liabilities	85,845			(820		)	85,025			85,845			(418		)	85,427
Total	$	320,241		$	(182,634	)	$	137,607		$	320,241		$	(179,848	)	$	140,393
Other:
Distribution channel	$	20,000		$	(6,110	)	$	13,890		$	20,000		$	(5,444	)	$	14,556
Technology	15,000			(14,654		)	346			15,000			(13,210		)	1,790
Brand	7,000			(3,209		)	3,791			7,000			(2,859		)	4,141
Total	$	42,000		$	(23,973	)	$	18,027		$	42,000		$	(21,513	)	$	20,487
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

Deferred charges on retroactive reinsurance	$	278,643		$	(207,250	)	$	71,393		$278,643			$	(198,451	)	$80,192

Debt Obligations

6 Months Ended

Jun. 30, 2018

Debt Disclosure [Abstract]

DEBT OBLIGATIONS

14. DEBT OBLIGATIONS

We utilize debt arrangements primarily for acquisitions and, from time to time, for general corporate purposes. Debt obligations as at June 30, 2018 and December 31, 2017 were as follows:



Facility	Origination Date	Term	June 30, 2018			December 31, 2017
Senior Notes	March 10, 2017	5 years	$	350,000		$	350,000
Less: Unamortized debt issuance costs			(2,285		)	(2,484		)
Total Senior Notes			347,715			347,516
EGL Revolving Credit Facility	September 16, 2014	5 years	91,895			225,110
EGL Term Loan Facility	November 18, 2016	3 years	—			74,063
Total debt obligations			$	439,610		$	646,689

For the three months ended June 30, 2018 and 2017, interest expense on our debt obligations was $8.7 million and $6.8 million, respectively. For the six months ended June 30, 2018 and 2017, interest expense on our debt obligations was $16.1 million and $13.0 million, respectively.

Senior Notes

On March 10, 2017, we issued Senior Notes (the "Notes") for an aggregate principal amount of $350.0 million. The Notes pay 4.5% interest semi-annually and mature on March 10, 2022. The 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 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 Notes 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 Notes. On or after the date that is one month prior to the maturity of the 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 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 Notes and are included in interest expense in our unaudited condensed consolidated statements of earnings.

EGL Revolving Credit Facility

This five-year revolving credit facility, originated on September 16, 2014 and most recently amended on March 20, 2017, is among Enstar Group Limited and certain of its subsidiaries, as borrowers and as guarantors, and various financial institutions. As at June 30, 2018, we were permitted to borrow up to an aggregate of $831.3 million under the facility. As at June 30, 2018, there was $739.4 million of available unutilized capacity under this facility. We are in compliance with the covenants of the EGL Revolving Credit Facility. Subsequent to June 30, 2018, we reduced the maximum borrowings capacity under the facility to $600.0 million, and repaid $13.9 million, bringing the unutilized capacity under this facility to $522.0 million.

As at June 30, 2018 and December 31, 2017, there were borrowings of €60.0 million ($70.1 million) and €50.0 million ($60.1 million), respectively, under the facility that were designated as non-derivative hedges of our net investment in certain subsidiaries whose functional currency is denominated in Euros.

EGL Term Loan Facility

On November 18, 2016, we entered into and fully utilized a three-year $75.0 million unsecured term loan (the "EGL Term Loan Facility"). A portion of the proceeds from the issuance of our Series D Preferred Shares was used to fully repay this facility and the facility was terminated in the three months ended June 30, 2018.

Refer to Note 15 - "Debt Obligations" of the consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2017 for further information on the terms of the above facilities.

Noncontrolling Interests

6 Months Ended

Jun. 30, 2018

Noncontrolling Interest [Abstract]

NONCONTROLLING INTERESTS

15. NONCONTROLLING INTERESTS

Redeemable Noncontrolling Interest

Redeemable noncontrolling interest ("RNCI") as at June 30, 2018 and December 31, 2017 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 as at June 30, 2018 and December 31, 2017:



	Six Months Ended June 30, 2018			Year Ended December 31, 2017
Balance at beginning of period	$	479,606		$	454,522
Dividends paid	—			(27,458		)
Net earnings (losses) attributable to RNCI	(8,021		)	19,619
Accumulated other comprehensive earnings (losses) attributable to RNCI	(381		)	1,945
Change in redemption value of RNCI	(111		)	30,978
Balance at end of period	$	471,093		$	479,606

We carried the RNCI at its estimated redemption value, which is fair value, as of June 30, 2018. The decrease was primarily attributable to a decrease in the net assets due to net losses during the six months ended June 30, 2018.

Refer to Note 20 - "Related Party Transactions" and Note 21 - "Commitments and Contingencies" for additional information regarding RNCI.

Noncontrolling Interest

As at June 30, 2018 and December 31, 2017, we had $9.7 million and $9.3 million, respectively, of noncontrolling interest ("NCI") primarily related to an external interest in one of our non-life run-off subsidiaries.

Share Capital	6 Months Ended
Share Capital	Jun. 30, 2018
Equity [Abstract]
SHARE CAPITAL	16. SHARE CAPITAL Issue of Voting ordinary shares and Series E non-voting ordinary shares On May 14, 2018, an aggregate of 2,007,017 of our ordinary shares were issued to the shareholders of KaylaRe, comprising 1,501,778 voting ordinary shares and 505,239 Series E non-voting ordinary shares. The shares were consideration for the acquisition of KaylaRe Holdings Ltd, as described in Note 2 - "Acquisitions". Issue of Series D Preferred Shares On June 28, 2018, the Company raised $400.0 million through the public offering of 16,000 shares of its 7.00% non-cumulative fixed-to-floating rate Series D perpetual preferred shares ("Series D Preferred Shares") (equivalent to 16,000,000 depositary shares, each of which represents a 1/1,000th interest in a Series D Preferred Share), $1.00 par value and $25,000 liquidation preference (the "Liquidation Preference") per share (equivalent to $25.00 per Depositary Share). After underwriting discounts and other expenses, the Company received net proceeds of $389.5 million which was used to repay a portion of amounts outstanding under the EGL Revolving Credit Facility and repaid in full the EGL Term Loan Facility. The Series D Preferred Shares are not redeemable prior to September 1, 2028, except in specified circumstances relating to certain tax, corporate, capital or rating agency events as described in the prospectus supplement relating to the offering. On and after September 1, 2028, the Series D Preferred Shares, represented by the depositary shares, will be redeemable at the Company’s option, in whole or from time to time in part, at a redemption price equal to $25,000 per Series D Preferred Share (equivalent to $25.00 per depositary share), plus any declared and unpaid dividends. Holders of Series D Preferred Shares will be entitled to receive, only when, as and if declared, non-cumulative cash dividends, paid quarterly in arrears on the 1st day of March, June, September and December of each year, commencing on September 1, 2018, in an amount per share equal to 7.00% of the Liquidation Preference per annum (equivalent to $1,750.00 per Series D Preferred Share and $1.75 per depositary share per annum) up to but excluding September 1, 2028. Commencing on September 1, 2028, which is the commencement date of the floating rate period, quarterly dividends on the Series D Preferred Shares will be payable, on a non-cumulative basis, when, as and if declared, at a floating rate equal to three-month LIBOR plus 4.015% of the Liquidation Preference per annum. Dividends that are not declared will not accumulate and will not be payable. On July 31, 2018, our Board of Directors declared a cash dividend of $320.83 per Series D Preferred share (equivalent to $0.32083 per depositary share), payable on September 1, 2018 to shareholders of record on August 15, 2018. Refer to Note 17 - "Share Capital" of the consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2017 for additional information on our share capital.

Earnings Per Share

6 Months Ended

Jun. 30, 2018

Earnings Per Share [Abstract]

EARNINGS PER SHARE

17. EARNINGS PER SHARE

The following table sets forth the computation of basic and diluted net earnings per share for the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30,					Six Months Ended June 30,
	2018		2017			2018			2017
Numerator:
Net earnings (loss) from continuing operations	$	8,244	$	95,057		$	(32,966	)	$	149,366
Net loss from discontinued operations	—		(4,871		)	—			(4,500		)
Net earnings (loss) attributable to Enstar Group Limited	8,244		90,186			(32,966		)	144,866
Denominator:
Weighted average ordinary shares outstanding — basic	20,462,788		19,387,650			19,938,815			19,381,225
Effect of dilutive securities:
Share-based compensation plans	128,232		53,720			122,471			54,182
Warrants	80,212		70,059			79,081			70,670
Weighted average ordinary shares outstanding — diluted	20,671,232		19,511,429			20,140,367			19,506,077
Earnings (losses) per share attributable to Enstar Group Limited:
Basic:
Net earnings (loss) from continuing operations	$	0.40	$	4.90		$	(1.65	)	$	7.71
Net loss from discontinued operations	—		(0.25		)	$	—		$	(0.23	)
Net earnings (loss) per ordinary share	$	0.40	$	4.65		$	(1.65	)	$	7.48
Diluted⁽¹⁾:
Net earnings (loss) from continuing operations	$	0.40	$	4.87		$	(1.65	)	$	7.66
Net loss from discontinued operations	—		(0.25		)	$	—		$	(0.23	)
Net earnings (loss) per ordinary share	$	0.40	$	4.62		$	(1.65	)	$	7.43

⁽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

6 Months Ended

Jun. 30, 2018

Retirement Benefits [Abstract]

SHARE-BASED COMPENSATION AND PENSIONS

18. 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" to the consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2017.

The table below provides the expenses related to the share-based compensation plans, employee share purchase plan, and pension plans for the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017

Share-based Compensation Expense	$	4,454	$	6,155	$	10,519	$	9,979

Employee Share Purchase Plan	$	127	$	58	$	210	$	166

Pension Expense	$	3,184	$	3,182	$	5,822	$	5,485

Taxation	6 Months Ended
Taxation	Jun. 30, 2018
Income Tax Disclosure [Abstract]
TAXATION	19. TAXATION Interim Tax Calculation Method We 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 and six months ended June 30, 2018 were 104.1% and (10.4)%, respectively, as compared to 4.2% and 1.0%, respectively for the comparatives periods in 2017. 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 Asset We 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 and six months ended June 30, 2018, we had no change in our assessment of our valuation allowance on deferred tax assets. Accounting for Uncertainty in Income Taxes There were no unrecognized tax benefits relating to uncertain tax positions as at June 30, 2018 and December 31, 2017. Tax Examinations Our 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 2012.

Related Party Transactions

6 Months Ended

Jun. 30, 2018

RELATED PARTY TRANSACTIONS

20. RELATED PARTY TRANSACTIONS

Stone Point Capital LLC

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 Capital LLC ("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 Atrium/Arden and StarStone transactions in cash at fair market value within the 90 days following September 6, 2018 and April 1, 2019, respectively, and at any time following September 6, 2020 and April 1, 2021, respectively; and (ii) Trident’s right to have its equity co-investment interests 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. As at June 30, 2018 and December 31, 2017, the RNCI on our balance sheet relating to these Trident co-investment transactions was as follows:



	June 30, 2018	December 31, 2017
Redeemable Noncontrolling Interest	451,490	459,649

As at June 30, 2018, 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; and


•	A separate account managed by Sound Point Capital, with respect to which we incurred management fees.

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:



	June 30, 2018		December 31, 2017
Investments in funds managed by Stone Point	$	366,279	$	255,905
Investments in registered investment companies affiliated with entities owned by Trident	40,422		22,060
Investments managed by Eagle Point Credit Management and PRIMA Capital Advisors	216,695		183,448
Investments in funds managed by Sound Point Capital	20,097		27,429
Investments in CLO equity securities with Sound Point Capital as collateral manager	17,137		17,760
Separate account managed by Sound Point Capital	65,182		63,572

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 June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Net unrealized gains on funds managed by Stone Point	$	3,778		$	4,682		$	2,252		$	11,650
Net unrealized gains (losses) on registered investment companies affiliated with entities owned by Trident	344			(171		)	6,549			5,037
Interest income on registered investment companies affiliated with entities owned by Trident	828			771			1,910			1,274
Management fees on investments managed by Eagle Point Credit Management and PRIMA Capital Advisors	(227		)	(151		)	(454		)	(291		)
Net unrealized gains (losses) on investments in funds managed by Sound Point Capital	291			433			(238		)	794
Net unrealized (losses) on investments in CLO equity securities with Sound Point Capital as collateral manager	(392		)	(383		)	(623		)	(2,494		)
Interest income on investments in CLO equity securities with Sound Point Capital as collateral manager	1,179			1,292			2,489			2,479
Management fees on separate account managed by Sound Point Capital	(80		)	(81		)	(161		)	(153		)

CPPIB

Canada Pension Plan Investment Board ("CPPIB") owns approximately 8.4% of our voting ordinary shares and additional non-voting shares that, together with its voting ordinary shares held indirectly, represented an economic interest of approximately 17.9% as of June 30, 2018. Poul Winslow, of CPPIB, was appointed to our Board on September 29, 2015 in connection with CPPIB's shareholder rights agreement with us. Approximately 4.1% of our voting ordinary shares are held indirectly by CPPIB through CPPIB Epsilon Ontario Limited Partnership ("CPPIB LP"). CPPIB is the sole limited partner of CPPIB LP. CPPIB Epsilon Ontario Trust ("CPPIB Trust") is the general partner of CPPIB LP, and Mr. Winslow is a trustee of CPPIB Trust. By virtue of his role as a trustee of CPPIB Trust, in its capacity as general partner of CPPIB LP, Mr. Winslow has shared voting and shared dispositive power over the shares, but has no pecuniary interest in the shares.

We also have a pre-existing reinsurance balances recoverable based on normal commercial terms from Continental Assurance Company, a company acquired by Wilton Re Ltd. ("Wilton Re"). CPPIB, together with management of Wilton Re, owns 100% of the common stock of Wilton Re. The reinsurance recoverable on our consolidated balance sheet as at June 30, 2018 and December 31, 2017 was as follows:



	June 30, 2018		December 31, 2017
Reinsurance balances recoverable	$	6,992	$	7,003

KaylaRe

On May 14, 2018, the Company completed the previously announced transaction to acquire all of the outstanding shares and warrants of KaylaRe, following the receipt of all required regulatory approvals. In consideration for the acquired shares and warrants of KaylaRe, 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 2 - "Acquisitions" for additional information.

On 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, pursuant to the conclusion that we were not required to consolidate following an analysis based on the guidance in ASC 810 - Consolidation. Our investment in the common shares and warrants of KaylaRe was carried at $320.1 million and $309.8 million in other assets on our consolidated balance sheet as at May 14, 2018 and December 31, 2017, respectively.

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 have 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. As of January 1, 2018, the reinsurance of StarStone's U.S. entities was non-renewed.

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, on a funds held basis. 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 net incurred losses to KaylaRe Ltd. during three and six months ended June 30, 2018 and 2017.

Our consolidated balance sheets as at December 31, 2017 included the following balances related to transactions between us and KaylaRe and KaylaRe Ltd.:



	December 31, 2017
Reinsurance balances recoverable	$	357,355
Prepaid reinsurance premiums	116,356
Funds held	174,181
Insurance and reinsurance balances payable	232,884
Ceded acquisition costs	36,070

Our consolidated statement of earnings as at June 30, 2018 and June 30, 2017 included the following balances related to transactions between us and KaylaRe and KaylaRe Ltd.:



	Six Months Ended June 30,
	2018		2017
Fee income due to Enstar Limited	$	1,453	$	—

Transactions under KaylaRe-StarStone QS:
Ceded premium earned	52,651		113,354
Net incurred losses	31,654		60,156
Acquisition costs	18,774		45,373

Transactions under Fitzwilliam reinsurance agreement:
Profit Commission	—		7,816

Hillhouse

Gaoling Fund, L.P., YHG Investment, L.P. and Hillhouse Fund III L.P., investment 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 17.1% economic interest in Enstar. In February 2017, Jie Liu, a Managing Director of Hillhouse Capital, was appointed to our Board. In connection with Hillhouse Capital's investment in KaylaRe, Mr. Liu also served as a director of KaylaRe until resigning from that board in connection with the transaction described above.

As at December 31, 2017, KaylaRe had investments in a fund managed by Hillhouse. On May 14, 2018 KaylaRe was acquired (refer to Note 2 - "Acquisitions" for further details), at which point KaylaRe was consolidated and KaylaRe's investment in Hillhouse InRe Fund, L.P. was recorded within our other investments on consolidated balance sheet.

As at June 30, 2018, we had investments in each of Gaoling Fund, L.P., China Value Fund, L.P. and Hillhouse InRe Fund, L.P., which are funds managed by Hillhouse, with respect to which we recognized unrealized gains. Subsequent to June 30, 2018, we invested an additional $102.6 million in funds managed by Hillhouse.

Our consolidated statement of earnings as at June 30, 2018 and June 30, 2017 included the following balances related to transactions between us and Hillhouse and its affiliated entities:



	Three Months Ended June 30,		Six Months Ended June 30,
	2018		2018
Net unrealized gains	$	10,850	$	22,939

Monument

was established in October 2016 and Enstar has invested a total of $16.0 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, for a total consideration of €25.6 million (approximately $30.8 million). The total loss recorded on the sale of Laguna, for the year ended December 31, 2017 was $16.3 million, which included a cumulative currency translation adjustment balance of $6.3 million, which upon completion of the sale during the third quarter of 2017 was reclassified from accumulated other comprehensive income and included in earnings as a component of the loss on sale of Laguna.

Our investment in the common and preferred shares of Monument, carried in other assets on our consolidated balance sheet, as at June 30, 2018 and December 31, 2017 was as follows:



	June 30, 2018		December 31, 2017
Carrying value	$	21,871	$	15,960

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 at 20% indirect equity interest in Clear Spring.

We have recorded the investment in Clear Spring using the equity method basis of accounting, pursuant to the conclusion that we are not required to consolidate following an analysis based on the guidance in ASC 810 - Consolidation. Our investment in the common shares of Clear Spring, carried in other assets on our consolidated balance sheet, as at June 30, 2018 and December 31, 2017 was as follows:

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.

Our consolidated balance sheet as at June 30, 2018 and December 31, 2017 included the following balances related to transactions between us and Clear Spring:



	June 30, 2018		December 31, 2017
Balances under StarStone quota share:
Reinsurance balances recoverable	$	16,166	$	9,053
Prepaid insurance premiums	14,859		13,747
Ceded payable	15,925		13,964
Ceded acquisition costs	3,545		3,186

Balances under Cavello quota share:
Losses and LAE	554		—
Unearned reinsurance premiums	253		3,437
Funds held	1,400		5,095

Our consolidated statement of earnings as at June 30, 2018 and June 30, 2017 included the following balances related to transactions between us and Clear Spring:



	Three Months Ended June 30,					Six Months Ended June 30,
	2018			2017		2018		2017

Balances under StarStone quota share:
Ceded premium earned	$	7,636		$	—	$	14,638	$	—
Net incurred losses and LAE	3,044			—		8,606		—
Acquisition costs	2,129			—		3,911		—

Balances under Cavello quota share:
Premium earned	158			—		1,909		—
Net incurred losses and LAE	(629		)	—		761		—
Acquisition costs	91			—		555		—

AmTrust

Effective July 23, 2018 the Company entered into a Subscription Agreement with Evergreen Parent L.P. ("Evergreen"), K-Z Evergreen, LLC and Trident Pine Acquisition LP ("Trident Pine"). Evergreen is an entity formed by private equity funds managed by Stone Point and the Karfunkel-Zyskind family that intends to acquire 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 do not presently own or control. The transaction was approved by AmTrust’s stockholders on June 21, 2018, and is expected to close during the second half of 2018, subject to the satisfaction of customary closing conditions, including approval by regulatory authorities.

Pursuant to the Subscription Agreement, and subject to the conditions therein, Enstar or one or more of its controlled, majority-owned affiliates, agreed to purchase equity in Evergreen in the aggregate amount of $200.0 million. The equity interest will be in the form of three separate classes of equity securities issued at the same price and in the same proportion as the equity interest to be purchased by Trident Pine. Following the closing of the transaction, Enstar is expected to own approximately 7.4% of the capital units and 6.2% of the indirect voting rights of Evergreen. Among other conditions, the closing under the Subscription Agreement is contingent on the closing of Evergreen’s transaction with respect to AmTrust.

Citco

In 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 June 30, 2018, 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.

Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	21. COMMITMENTS AND CONTINGENCIES Concentrations 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 9 - "Reinsurance Balances Recoverable". 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 $1,051.3 million to one reinsured company which has financial strength credit ratings of A+ from A.M. Best and AA from Standard & Poor's. We limit the amount of credit exposure to any one counterparty, and none of our counterparty credit exposures, excluding U.S. and the United Kingdom government instruments and the funds held counterparty noted above, exceeded 10% of shareholders’ equity as at June 30, 2018. Our credit exposure to the U.S. and the United Kingdom governments was $843.2 million, and $388.1 million, respectively, as at June 30, 2018. Legal Proceedings We are, from time to time, involved in various legal proceedings in the ordinary course of business, including litigation and arbitration regarding claims. Estimated losses relating to claims arising in the ordinary course of business, including the anticipated outcome of any pending arbitration or litigation, are included in the liability for losses and LAE in our consolidated balance sheets. In addition to claims litigation, we may be subject to other lawsuits and regulatory actions in the normal course of business, which may involve, among other things, allegations of underwriting errors or omissions, employment claims or regulatory activity. We do not believe that the resolution of any currently pending legal proceedings, either individually or taken as a whole, will have a material effect on our business, results of operations or financial condition. We anticipate that, similar to the rest of the 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 Commitments As at June 30, 2018, we had unfunded commitments to investment funds of $200.0 million. Guarantees As at June 30, 2018 and December 31, 2017, parental guarantees and capital instruments supporting subsidiaries' policyholder obligations were $618.7 million and $630.7 million, respectively. On February 8, 2018, we amended and restated the FAL Facility to issue up to $325.0 million of letters of credit, with a 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. Asbestos Personal Injury Liabilities We acquired Dana Companies, LLC ("Dana") 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, 2017. Dana continues to process asbestos personal injury claims in the normal course of business and is separately managed. Other liabilities included $192.2 million and $205.7 million for indemnity and defense costs for pending and future claims at June 30, 2018 and December 31, 2017, respectively, determined using standard actuarial techniques for asbestos-related exposures. Other liabilities also included $2.2 million and $2.2 million for environmental liabilities associated with Dana properties at June 30, 2018 and December 31, 2017, respectively. Other assets included $117.9 million and $122.3 million at June 30, 2018 and December 31, 2017, respectively, for 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. Redeemable Noncontrolling Interest We have the right to purchase the RNCI interests from the RNCI holders at certain times in the future (each such right, a "call right"), and the RNCI holders have the right to sell their RNCI interests to us at certain times in the future (each such right, a "put right"). The RNCI rights held by Trident are described in Note 20 - "Related Party Transactions". Dowling has a right to participate if Trident exercises its put right.

Segment Information

6 Months Ended

Jun. 30, 2018

Segment Reporting [Abstract]

SEGMENT INFORMATION

the second half of 2017, following the completion of the sale of our Laguna and Pavonia businesses, which significantly reduced the size of our life and annuities business, we undertook a review of our reportable segments. Following this review we determined that we have three reportable segments of business that are each managed, operated and reported on separately: (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. The change in reportable segments had no impact on our previously reported historical consolidated financial positions, results of operations or cash flows. These segments are described in Note 1 - "Description of Business" and Note 24 - "Segment Information" to the consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2017.

The following tables set forth selected and unaudited condensed consolidated statement of earnings results by segment for the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30, 2018
	Non-Life Run-Off			Atrium			StarStone			Other			Total
Gross premiums written	$	(938	)	$	41,560		$	301,353		$	975		$	342,950

Net premiums written	$	(1,661	)	$	34,583		$	219,238		$	1,059		$	253,219

Net premiums earned	$	9,609		$	34,522		$	183,621		$	1,060		$	228,812
Net incurred losses and LAE	70,134			(16,926		)	(146,027		)	—			(92,819		)
Life and Annuity Policy Benefits	—			—			—			160			160
Acquisition costs	(3,214		)	(12,716		)	(37,271		)	(133		)	(53,334		)
Operating expenses	(38,378		)	(4,130		)	(34,142		)	—			(76,650		)
Underwriting income (loss)	38,151			750			(33,819		)	1,087			6,169
Net investment income	57,291			1,285			8,745			(852		)	66,469
Net realized and unrealized losses	(46,027		)	(680		)	(3,181		)	(4,530		)	(54,418		)
Fees and commission income	4,487			3,865			—			—			8,352
Other income (expense)	6,311			56			(600		)	527			6,294
Corporate expenses	(13,387		)	(1,838		)	—			(10,737		)	(25,962		)
Interest income (expense)	(10,081		)	—			(6		)	1,165			(8,922		)
Net foreign exchange gains (losses)	6,958			(47		)	(1,573		)	181			5,519
EARNINGS (LOSS) BEFORE INCOME TAXES	43,703			3,391			(30,434		)	(13,159		)	3,501
INCOME TAXES	(1,219		)	(739		)	(1,688		)	—			(3,646		)
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	42,484			2,652			(32,122		)	(13,159		)	(145		)
Net loss (earnings) attributable to noncontrolling interest	(1,094		)	(1,121		)	10,604			—			8,389
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$	41,390		$	1,531		$	(21,518	)	$	(13,159	)	$	8,244

Underwriting ratios:
Loss ratio⁽¹⁾				49.0		%	79.5		%
Acquisition expense ratio ⁽¹⁾				36.8		%	20.3		%
Operating expense ratio⁽¹⁾				12.0		%	18.6		%
Combined ratio ⁽¹⁾				97.8		%	118.4		%

⁽¹⁾Refer to "Underwriting Ratios" for a description of how these ratios are calculated.



	Six Months Ended June 30, 2018
	Non-Life Run-Off			Atrium			StarStone			Other			Total
Gross premiums written	$	6,442		$	91,002		$	606,342		$	2,012		$	705,798

Net premiums written	$	(1,561	)	$	76,077		$	399,801		$	2,049		$	476,366

Net premiums earned	$	16,787		$	69,745		$	310,447		$	2,052		$	399,031
Net incurred losses and LAE	143,112			(34,098		)	(221,367		)	—			(112,353		)
Life and Annuity Policy Benefits	—			—			—			206			206
Acquisition costs	(4,684		)	(24,781		)	(53,696		)	(281		)	(83,442		)
Operating expenses	(76,781		)	(8,307		)	(68,699		)	—			(153,787		)
Underwriting income (loss)	78,434			2,559			(33,315		)	1,977			49,655
Net investment income	108,942			2,470			16,446			4,930			132,788
Net realized and unrealized gains (losses)	(172,323		)	(2,083		)	(16,139		)	(6,903		)	(197,448		)
Fees and commission income	9,385			7,298			—			—			16,683
Other income (expense)	23,566			120			(549		)	(203		)	22,934
Corporate expenses	(22,020		)	(2,313		)	—			(19,752		)	(44,085		)
Interest income (expense)	(18,611		)	—			(547		)	2,225			(16,933		)
Net foreign exchange gains (losses)	(219		)	(1,000		)	(478		)	1,348			(349		)
EARNINGS (LOSS) BEFORE INCOME TAXES	7,154			7,051			(34,582		)	(16,378		)	(36,755		)
INCOME TAXES	(102		)	(1,019		)	(2,686		)	(11		)	(3,818		)
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	7,052			6,032			(37,268		)	(16,389		)	(40,573		)
Net loss (earnings) attributable to noncontrolling interest	(2,523		)	(2,532		)	12,662			—			7,607
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$	4,529		$	3,500		$	(24,606	)	$	(16,389	)	$	(32,966	)

Underwriting ratios:
Loss ratio⁽¹⁾				48.9		%	71.3		%
Acquisition expense ratio ⁽¹⁾				35.5		%	17.3		%
Operating expense ratio⁽¹⁾				11.9		%	22.1		%
Combined ratio ⁽¹⁾				96.3		%	110.7		%

⁽¹⁾Refer to "Underwriting Ratios" for a description of how these ratios are calculated.



	Three Months Ended June 30, 2017
	Non-Life Run-Off			Atrium			StarStone			Other			Total
Gross premiums written	$	1,222		$	34,565		$	224,564		$	582		$	260,933

Net premiums written	$	1,905		$	31,327		$	115,534		$	782		$	149,548

Net premiums earned	$	3,365		$	32,380		$	118,551		$	1,275		$	155,571
Net incurred losses and LAE	64,402			(8,189		)	(65,833		)	—			(9,620		)
Life and Annuity Policy Benefits	—			—			—			(4,289		)	(4,289		)
Acquisition costs	946			(12,057		)	(17,698		)	(1,546		)	(30,355		)
Operating expenses	(31,668		)	(6,313		)	(32,950		)	—			(70,931		)
Underwriting income (loss)	37,045			5,821			2,070			(4,560		)	40,376
Net investment income	39,572			861			7,189			1,795			49,417
Net realized and unrealized gains (losses)	50,556			474			7,209			(6,362		)	51,877
Fees and commission income (expense)	10,817			8,070			—			(220		)	18,667
Other income	10,769			50			33			4			10,856
Corporate expenses	(22,793		)	(3,637		)	—			(9,129		)	(35,559		)
Interest income (expense)	(7,646		)	(265		)	(644		)	982			(7,573		)
Net foreign exchange losses	(2,160		)	(3,480		)	(815		)	(667		)	(7,122		)
Loss on sale of subsidiary	—			—			—			(9,609		)	(9,609		)
EARNINGS (LOSS) BEFORE INCOME TAXES	116,160			7,894			15,042			(27,766		)	111,330
INCOME TAXES	(3,679		)	(368		)	(679		)	(5		)	(4,731		)
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	112,481			7,526			14,363			(27,771		)	106,599
NET LOSS FROM DISCONTINUED OPERATIONS, NET OF INCOME TAX EXPENSE	—			—			—			(4,871		)	(4,871		)
NET EARNINGS (LOSS)	112,481			7,526			14,363			(32,642		)	101,728
Net earnings attributable to noncontrolling interest	(2,621		)	(3,087		)	(5,834		)	—			(11,542		)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$	109,860		$	4,439		$	8,529		$	(32,642	)	$	90,186

Underwriting ratios:
Loss ratio⁽¹⁾				25.3		%	55.5		%
Acquisition expense ratio ⁽¹⁾				37.2		%	14.9		%
Operating expense ratio⁽¹⁾				19.5		%	27.9		%
Combined ratio ⁽¹⁾				82.0		%	98.3		%

⁽¹⁾Refer to "Underwriting Ratios" for a description of how these ratios are calculated.



	Six Months Ended June 30, 2017
	Non-Life Run-Off			Atrium			StarStone			Other			Total
Gross premiums written	$	2,205		$	80,978		$	451,100		$	2,082		$	536,365

Net premiums written	$	1,986		$	73,246		$	234,400		$	1,975		$	311,607

Net premiums earned	$	3,441		$	64,600		$	233,959		$	2,469		$	304,469
Net incurred losses and LAE	67,159			(20,677		)	(133,994		)	—			(87,512		)
Life and Annuity Policy Benefits	—			—			—			(3,988		)	(3,988		)
Acquisition costs	546			(22,829		)	(28,312		)	(581		)	(51,176		)
Operating expenses	(61,110		)	(9,720		)	(66,971		)	—			(137,801		)
Underwriting income (loss)	10,036			11,374			4,682			(2,100		)	23,992
Net investment income	75,301			1,985			12,638			8,232			98,156
Net realized and unrealized gains (losses)	102,114			892			13,908			(6,518		)	110,396
Fees and commission income (expense)	19,540			11,442			1,166			(1,567		)	30,581
Other income	22,697			119			79			159			23,054
Corporate expenses	(46,142		)	(7,441		)	—			(17,574		)	(71,157		)
Interest income (expense)	(14,327		)	(536		)	(1,266		)	1,688			(14,441		)
Net foreign exchange losses	(2,937		)	(4,312		)	(2,708		)	(880		)	(10,837		)
Loss on sale of subsidiary	—			—			—			(9,609		)	(9,609		)
EARNINGS (LOSS) BEFORE INCOME TAXES	166,282			13,523			28,499			(28,169		)	180,135
INCOME (TAXES) BENEFIT	(4,639		)	(724		)	3,570			(9		)	(1,802		)
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	161,643			12,799			32,069			(28,178		)	178,333
NET LOSS FROM DISCONTINUED OPERATIONS, NET OF INCOME TAX EXPENSE	—			—			—			(4,500		)	(4,500		)
NET EARNINGS (LOSS)	161,643			12,799			32,069			(32,678		)	173,833
Net earnings attributable to noncontrolling interest	(10,630		)	(5,250		)	(13,087		)	—			(28,967		)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$	151,013		$	7,549		$	18,982		$	(32,678	)	$	144,866

Underwriting ratios:
Loss ratio⁽¹⁾				32.0		%	57.3		%
Acquisition expense ratio ⁽¹⁾				35.3		%	12.1		%
Operating expense ratio⁽¹⁾				15.1		%	28.6		%
Combined ratio ⁽¹⁾				82.4		%	98.0		%

⁽¹⁾Refer to "Underwriting Ratios" for a description of how these ratios are calculated.

Assets by Segment

Invested assets are managed on a subsidiary-by-subsidiary basis, and investment income and realized and unrealized gains (losses) on investments are recognized in each segment as earned. Our total assets as at June 30, 2018 and December 31, 2017 by segment were as follows:



	June 30,			December 31,
	2018			2017
Assets by Segment:
Non-life Run-off	$	11,997,250		$	10,368,105
Atrium	584,631			556,637
StarStone	3,113,207			3,128,725
Other	(491,876		)	(447,045		)
Total assets	$	15,203,212		$	13,606,422

Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2018

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, 2017. All significant inter-company transactions and balances have been eliminated. Results of operations for acquired subsidiaries are included from the date of acquisition. 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;


•	gross and net premiums written and net premiums earned;


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


•	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 2018

Accounting Standards Update ("ASU") 2017-09, Stock Compensation - Scope of Modification Accounting

ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost

ASU 2017-05, Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets

ASU 2016-16, Intra-Entity Transfers of Assets Other Than Inventory

ASU 2016-15, Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments

ASU 2016-01, Recognition and Measurement of Financial Instruments

ASUs 2014-09, 2016-08, 2016-10, 2016-12, Revenue from Contracts with Customers

Recently Issued Accounting Pronouncements Not Yet Adopted

ASU 2018-11, Targeted Improvements to ASC 842 - Leases and ASU 2018-10, Codification Improvements to ASC 842 - Leases

ASU 2018-09, Codification Improvements

Acquisitions (Tables)

6 Months Ended

Jun. 30, 2018

Business Combinations [Abstract]

Schedule of Acquisitions

Purchase Price

The components of the consideration paid to acquire all of the outstanding shares and warrants of KaylaRe were as follows:



Fair value of Enstar ordinary shares issued	$	414,750
Fair value of previously held equity method investment	336,137
Adjustment for the fair value of preexisting relationships	37,169
Total purchase price	$	788,056
Net assets acquired at fair value (excluding preexisting relationships)	$	746,320
Excess of purchase price over fair value of net assets acquired	$	41,736



Carrying value of previously held equity method investment prior to the close of the transaction	$	320,130
Price-to-book multiple	1.05
Fair value of previously held equity method investment prior to the close of the transaction	$	336,137

Gain recognized on remeasurement of previously held equity method investment to fair value	$	16,007



Number of Enstar Ordinary shares issued	2,007,017
Closing price of Enstar Ordinary shares as of May 14, 2018	$	206.65
Fair value of Enstar Ordinary shares issued to shareholders of KaylaRe	$	414,750



ASSETS	Carrying value			Fair value			Loss on deemed settlement
Funds held by reinsured companies	$	386,793		$	386,793		$	—
Deferred acquisition costs/Value of business acquired	33,549			40,268			6,719
TOTAL ASSETS	420,342			427,061			6,719
LIABILITIES
Losses and LAE	339,747			333,205			(6,542		)
Unearned premiums	105,602			105,602			—
Insurance and reinsurance balances payable	25,897			23,559			(2,338		)
Other liabilities	1,864			1,864			—
TOTAL LIABILITIES	473,110			464,230			(8,880		)
NET ASSETS (LIABILITIES)	$	(52,768	)	$	(37,169	)	$	15,599

Fair Values of Assets Acquired and Liabilities Assumed



ASSETS
Fixed maturities, trading, at fair value	$	126,393
Other investments, at fair value	626,476
Total investments	752,869
Cash and cash equivalents	5,657
Premiums receivable	10,965
Deferred acquisition costs	275
Other assets	614
TOTAL ASSETS	$	770,380
LIABILITIES
Losses and LAE	$	4,059
Unearned premiums	10,984
Insurance and reinsurance balances payable	13
Other liabilities	9,004
TOTAL LIABILITIES	24,060
NET ASSETS ACQUIRED AT FAIR VALUE	$	746,320

Results of Operations of Acquiree

The table below summarizes the results of the KaylaRe operations which are included in our condensed consolidated statement of earnings from the acquisition date to June 30, 2018:



Premiums earned	$	5,381
Incurred losses and LAE	(4,960		)
Acquisition costs	(135		)
Underwriting income	286
Net investment income	791
Net unrealized gains	15,247
	$	16,324

Divestitures, Held-For-Sale Businesses and Discontinued Operations (Tables)

6 Months Ended

Jun. 30, 2018

Discontinued Operations and Disposal Groups [Abstract]

Financial Information of Held-For-Sale Business

The following table summarizes the components of assets and liabilities held-for-sale on our consolidated balance sheet as at December 31, 2017:



	December 31, 2017
Assets:
Fixed maturities, trading, at fair value	$	20,770
Equities, trading, at fair value	765
Cash and cash equivalents	6,314
Restricted cash and cash equivalents	13
Reinsurance balances recoverable	1,728
Other assets	269
Assets of businesses held for sale	29,859
Less: Accrual of loss on sale	(5,508		)
Total assets held for sale	$	24,351

Liabilities:
Policy benefits for life and annuity contracts	$	10,666
Other liabilities	605
Total liabilities held for sale	$	11,271

The following table summarizes the components of net earnings from discontinued operations on the unaudited condensed consolidated statements of earnings for the three and six months ended June 30, 2017:



	Three Months Ended June 30,			Six Months Ended June 30,
	2017			2017
INCOME
Net premiums earned	$	13,605		$	27,930
Net investment income	10,277			20,306
Net realized and unrealized gains	1,154			2,776
Other income	395			755
	25,431			51,767
EXPENSES
Life and annuity policy benefits	24,112			44,782
Acquisition costs	2,280			4,316
General and administrative expenses	3,718			6,775
Other expenses	—			(16		)
	30,110			55,857
LOSS BEFORE INCOME TAXES	(4,679		)	(4,090		)
INCOME TAXES	(192		)	(410		)
NET LOSS FROM DISCONTINUED OPERATIONS	$	(4,871	)	$	(4,500	)

The following table presents the cash flows of Pavonia for the six months ended June 30, 2017:



	Six Months Ended June 30,
	2017
Operating activities	$	23,540
Investing activities	5,244
Change in cash and cash equivalents	$	28,784

- Definition

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

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+ Details

Investments (Tables)

6 Months Ended

Jun. 30, 2018

Investments, Debt and Equity Securities [Abstract]

Estimated Fair Values of Investments in Fixed Maturity Investments, Short-Term Investments and Equities, Trading Securities

The fair values of our fixed maturity investments, short-term investments and equities classified as trading were as follows:



	June 30, 2018		December 31, 2017
U.S. government and agency	$	536,132	$	554,036
Non-U.S. government	979,974		607,132
Corporate	3,787,366		3,363,060
Municipal	89,339		100,221
Residential mortgage-backed	306,025		288,713
Commercial mortgage-backed	403,001		421,548
Asset-backed	586,488		541,574
Total fixed maturity and short-term investments	6,688,325		5,876,284
Equities — U.S.	90,256		106,363
Equities — International	40,148		240
	$	6,818,729	$	5,982,887

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



As at June 30, 2018	Amortized Cost		Fair Value		% of Total Fair Value
One year or less	$	480,852	$	475,705	7.1	%
More than one year through two years	546,766		537,849		8.0	%
More than two years through five years	1,672,267		1,633,309		24.4	%
More than five years through ten years	1,476,591		1,435,235		21.5	%
More than ten years	1,325,143		1,310,713		19.6	%
Residential mortgage-backed	304,249		306,025		4.6	%
Commercial mortgage-backed	415,135		403,001		6.0	%
Asset-backed	584,876		586,488		8.8	%
	$	6,805,879	$	6,688,325	100.0	%



As at June 30, 2018	Amortized Cost		Fair Value		% of Total Fair Value
One year or less	$	20,321	$	19,692	11.6	%
More than one year through two years	20,422		20,211		11.9	%
More than two years through five years	40,382		40,544		24.0	%
More than five years through ten years	56,263		56,890		33.6	%
More than ten years	31,159		31,966		18.9	%
Residential mortgage-backed	18		18		—	%
	$	168,565	$	169,321	100.0	%

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 at June 30, 2018	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses Non-OTTI			Fair Value
U.S. government and agency	$	2,429	$	—	$	(9	)	$	2,420
Non-U.S. government	75,679		1,423		(915		)	76,187
Corporate	86,696		1,472		(1,184		)	86,984
Municipal	3,743		1		(32		)	3,712
Residential mortgage-backed	18		—		—			18
	$	168,565	$	2,896	$	(2,140	)	$	169,321



As at December 31, 2017	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses Non-OTTI			Fair Value
U.S. government and agency	$	4,210	$	—	$	(23	)	$	4,187
Non-U.S. government	84,776		1,249		(588		)	85,437
Corporate	113,561		2,436		(876		)	115,121
Municipal	5,146		8		(18		)	5,136
Residential mortgage-backed	31		—		—			31
Asset-backed	373		—		—			373
	$	208,097	$	3,693	$	(1,505	)	$	210,285

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 at June 30, 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	$	2,293	$	(8	)	$	127	$	(1	)	$	2,420	$	(9	)
Non-U.S. government	4,270		(390		)	18,007		(525		)	22,277		(915		)
Corporate	7,266		(822		)	24,914		(362		)	32,180		(1,184		)
Municipal	367		(7		)	2,913		(25		)	3,280		(32		)
Total fixed maturity investments	$	14,196	$	(1,227	)	$	45,961	$	(913	)	$	60,157	$	(2,140	)



	12 Months or Greater					Less Than 12 Months					Total
As at December 31, 2017	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	$	2,344	$	(16	)	$	1,842	$	(7	)	$	4,186	$	(23	)
Non-U.S. government	11,101		(373		)	20,965		(215		)	32,066		(588		)
Corporate	9,177		(807		)	24,200		(69		)	33,377		(876		)
Municipal	369		(5		)	3,605		(13		)	3,974		(18		)
Total fixed maturity investments	$	22,991	$	(1,201	)	$	50,612	$	(304	)	$	73,603	$	(1,505	)

Credit Ratings Company's Fixed Maturity and Short-Term Investments Available-for-Sale

The following table sets forth the credit ratings of our fixed maturity and short-term investments as at June 30, 2018:



	Amortized Cost		Fair Value		% of Total Investments		AAA Rated			AA Rated			A Rated			BBB Rated			Non- Investment Grade			Not Rated
Fixed maturity and short-term investments
U.S. government and agency	$	544,615	$	538,552	7.9	%	$	537,959		$	593		$	—		$	—		$	—		$	—
Non-U.S. government	1,061,120		1,056,161		15.4	%	375,722			568,567			46,510			59,407			5,955			—
Corporate	3,970,353		3,874,350		56.5	%	169,098			461,745			2,073,323			1,064,563			105,329			292
Municipal	94,078		93,051		1.4	%	18,303			58,518			12,811			3,419			—			—
Residential mortgage-backed	304,267		306,043		4.4	%	187,130			4,046			13,154			410			97,140			4,163
Commercial mortgage-backed	415,135		403,001		5.9	%	210,884			47,233			65,830			57,420			9,822			11,812
Asset-backed	584,876		586,488		8.5	%	263,152			52,827			117,250			75,577			77,211			471
Total	$	6,974,444	$	6,857,646	100.0	%	$	1,762,248		$	1,193,529		$	2,328,878		$	1,260,796		$	295,457		$	16,738
% of total fair value							25.7		%	17.4		%	34.0		%	18.4		%	4.3		%	0.2		%

Other Investments

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



	June 30, 2018		December 31, 2017
Private equities and private equity funds	$	252,965	$	289,556
Fixed income funds	342,166		229,999
Hedge funds	670,963		63,773
Equity funds	387,490		249,475
CLO equities	53,840		56,765
CLO equity fund	40,864		12,840
Private credit funds	14,319		10,156
Call options on equity	4,998		—
Other	728		828
	$	1,768,333	$	913,392

Schedule of Life Settlement Contracts, Investment Method

The following table presents further information regarding our investments in life settlements as at December 31, 2017:



	December 31, 2017
	Number of Contracts	Carrying Value		Face Value (Death Benefits)
Remaining Life Expectancy of Insureds:
0 – 1 year	—	$	—	$	—
1 – 2 years	11	17,655		29,471
2 – 3 years	10	7,524		19,906
3 – 4 years	20	16,119		32,411
4 – 5 years	13	13,960		32,730
Thereafter	162	70,363		390,843
Total	216	$	125,621	$	505,361

Major Categories of Net Investment Income

Major categories of net investment income for the three and six months ended June 30, 2018 and 2017 are summarized as follows:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Fixed maturity investments	$	48,147		$	33,741		$	92,035		$	64,071
Short-term investments and cash and cash equivalents	3,096			2,801			5,178			5,441
Funds held	2,754			311			5,883			350
Funds held - directly managed	9,588			8,603			18,214			15,605
Investment income from fixed maturities and cash and cash equivalents	63,585			45,456			121,310			85,467
Equity securities	1,352			1,137			2,842			1,863
Other investments	2,962			3,387			6,276			6,896
Life settlements and other	1,116			2,687			7,775			9,583
Investment income from equities and other investments	5,430			7,211			16,893			18,342
Gross investment income	69,015			52,667			138,203			103,809
Investment expenses	(2,546		)	(3,250		)	(5,415		)	(5,653		)
Net investment income	$	66,469		$	49,417		$	132,788		$	98,156

Realized Gain (Loss) on Investments

Components of net realized and unrealized gains and losses for the three and six months ended June 30, 2018 and 2017 were as follows:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, available-for-sale	$	20		$	177		$	27		$	337
Gross realized losses on fixed maturity securities, available-for-sale	(41		)	(75		)	(78		)	(86		)
Net realized losses on fixed maturity securities, trading	(3,566		)	65			(10,513		)	(987		)
Net realized gains on equity securities, trading	2,000			236			2,903			810
Net realized losses on funds held - directly managed	(1,041		)	(289		)	(945		)	(4,142		)
Total net realized gains (losses) on sale	$	(2,628	)	$	114		$	(8,606	)	$	(4,068	)
Net unrealized gains (losses):
Fixed maturity securities, trading	$	(45,967	)	$	11,226		$	(146,268	)	$	34,542
Equity securities, trading	487			1,871			4,322			10,557
Other Investments	7,791			19,696			(1,871		)	43,205
Change in fair value of embedded derivative on funds held – directly managed	(13,044		)	17,912			(40,925		)	24,840
Change in value of fair value option on funds held - directly managed	(1,057		)	1,058			(4,100		)	1,320
Total net unrealized gains (losses)	(51,790		)	51,763			(188,842		)	114,464
Net realized and unrealized gains (losses)	$	(54,418	)	$	51,877		$	(197,448	)	$	110,396

Unrealized Gain (Loss) on Investments

Components of net realized and unrealized gains and losses for the three and six months ended June 30, 2018 and 2017 were as follows:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, available-for-sale	$	20		$	177		$	27		$	337
Gross realized losses on fixed maturity securities, available-for-sale	(41		)	(75		)	(78		)	(86		)
Net realized losses on fixed maturity securities, trading	(3,566		)	65			(10,513		)	(987		)
Net realized gains on equity securities, trading	2,000			236			2,903			810
Net realized losses on funds held - directly managed	(1,041		)	(289		)	(945		)	(4,142		)
Total net realized gains (losses) on sale	$	(2,628	)	$	114		$	(8,606	)	$	(4,068	)
Net unrealized gains (losses):
Fixed maturity securities, trading	$	(45,967	)	$	11,226		$	(146,268	)	$	34,542
Equity securities, trading	487			1,871			4,322			10,557
Other Investments	7,791			19,696			(1,871		)	43,205
Change in fair value of embedded derivative on funds held – directly managed	(13,044		)	17,912			(40,925		)	24,840
Change in value of fair value option on funds held - directly managed	(1,057		)	1,058			(4,100		)	1,320
Total net unrealized gains (losses)	(51,790		)	51,763			(188,842		)	114,464
Net realized and unrealized gains (losses)	$	(54,418	)	$	51,877		$	(197,448	)	$	110,396

Schedule of Restricted Assets

The carrying value of our restricted assets, including restricted cash of $363.9 million and $257.7 million, as at June 30, 2018 and December 31, 2017, respectively, was as follows:



	June 30, 2018		December 31, 2017
Collateral in trust for third party agreements	$	3,399,091	$	3,118,892
Assets on deposit with regulatory authorities	585,922		599,829
Collateral for secured letter of credit facilities	133,277		151,467
Funds at Lloyd's ⁽¹⁾	417,333		234,833
	$	4,535,623	$	4,105,021

Funds Held - Directly Managed (Tables)

6 Months Ended

Jun. 30, 2018

Investments, Debt and Equity Securities [Abstract]

Carrying Value of Assets and Liabilities Underlying Funds Held - Directly Managed

The following table presents the fair values of assets and liabilities underlying the funds held - directly managed account as at June 30, 2018 and December 31, 2017:



	June 30, 2018		December 31, 2017
Fixed maturity investments:
U.S. government and agency	$	87,017	$	69,850
Non-U.S. government	22,625		2,926
Corporate	672,437		695,490
Municipal	58,933		58,930
Residential mortgage-backed	60,260		29,439
Commercial mortgage-backed	221,133		211,186
Asset-backed	98,339		97,565
Total fixed maturity investments	$	1,220,744	$	1,165,386
Other assets	9,152		14,554
	$	1,229,896	$	1,179,940

Contractual Maturities of Fixed Maturity Investments Underlying Funds Held - Directly Managed



As at June 30, 2018	Amortized Cost		Fair Value		% of Total Fair Value
One year or less	$	23,555	$	23,456	1.9	%
More than one year through two years	74,264		73,553		6.0	%
More than two years through five years	245,586		239,757		19.6	%
More than five years through ten years	268,392		256,849		21.1	%
More than ten years	256,716		247,397		20.3	%
Residential mortgage-backed	61,362		60,260		4.9	%
Commercial mortgage-backed	231,947		221,133		18.1	%
Asset-backed	98,360		98,339		8.1	%
	$	1,260,182	$	1,220,744	100.0	%

Funds Held - Directly Managed, by Credit Rating

Credit Ratings

The following table sets forth the credit ratings of the fixed maturity investments underlying the funds held - directly managed account as at June 30, 2018:



	Amortized Cost		Fair Value		% of Total Investments		AAA Rated			AA Rated			A Rated			BBB Rated			Non- Investment Grade

U.S. government and agency	$	87,996	$	87,017	7.1	%	$	87,017		$	—		$	—		$	—		$	—
Non-U.S. government	22,524		22,625		1.9	%	—			3,797			12,162			6,666			—
Corporate	699,234		672,437		55.1	%	7,783			25,828			309,495			327,782			1,549
Municipal	58,759		58,933		4.8	%	—			20,725			30,854			7,354			—
Residential mortgage-backed	61,362		60,260		4.9	%	59,733			—			—			—			527
Commercial mortgage-backed	231,947		221,133		18.1	%	212,766			6,401			1,966			—			—
Asset-backed	98,360		98,339		8.1	%	85,027			13,312			—			—			—
Total	$	1,260,182	$	1,220,744	100.0	%	$	452,326		$	70,063		$	354,477		$	341,802		$	2,076
% of total fair value							37.1		%	5.7		%	29.0		%	28.0		%	0.2		%

Net Investment Income

Major categories of net investment income underlying the funds held - directly managed for the three and six months ended June 30, 2018 and 2017 are summarized as follows:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Fixed maturity investments	$	9,817		$	8,817		$	18,635		$	16,302
Short-term investments and cash and cash equivalents	58			62			137			127
Gross investment income	9,875			8,879			18,772			16,429
Investment expenses	(287		)	(276		)	(558		)	(824		)
Investment income on funds held - directly managed	$	9,588		$	8,603		$	18,214		$	15,605

Net Realized and Unrealized Investment (Losses) Gains

Net realized gains (losses) and change in fair value for the three and six months ended June 30, 2018 and 2017 are summarized as follows:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Net realized losses on fixed maturity securities	$	(1,041	)	$	(289	)	$	(945	)	$	(4,142	)
Change in fair value of embedded derivative	(13,044		)	17,912			(40,925		)	24,840
Change in value of fair value option on funds held - directly managed	(1,057		)	1,058			(4,100		)	1,320
Net realized gains (losses) and change in fair value of funds held - directly managed	$	(15,142	)	$	18,681		$	(45,970	)	$	22,018

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

Categorized Investments Recorded at Fair Value among Levels



	December 31, 2017
	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	$	—	$	558,223	$	—	$	—	$	558,223
Non-U.S. government	—		692,569		—		—		692,569
Corporate	—		3,411,003		67,178		—		3,478,181
Municipal	—		105,357		—		—		105,357
Residential mortgage-backed	—		285,664		3,080		—		288,744
Commercial mortgage-backed	—		400,054		21,494		—		421,548
Asset-backed	—		514,055		27,892		—		541,947
	$	—	$	5,966,925	$	119,644	$	—	$	6,086,569
Equities:
Equities — U.S.	$	103,652	$	2,711	$	—	$	—	$	106,363
Equities — International	—		240		—		—		240
	$	103,652	$	2,951	$	—	$	—	$	106,603
Other investments:
Private equities and private equity funds	$	—	$	—	$	—	$	289,556	$	289,556
Fixed income funds	—		202,570		—		27,429		229,999
Hedge funds	—		—		—		63,773		63,773
Equity funds	—		121,046		—		128,429		249,475
CLO equities	—		—		56,765		—		56,765
CLO equity funds	—		—		—		12,840		12,840
Private credit funds	—		—		—		10,156		10,156
Other	—		—		314		514		828
	$	—	$	323,616	$	57,079	$	532,697	$	913,392
Total Investments	$	103,652	$	6,293,492	$	176,723	$	532,697	$	7,106,564
Funds Held - Directly Managed:
U.S. government and agency	$	—	$	69,850	$	—	$	—	$	69,850
Non-U.S. government	—		2,926		—		—		2,926
Corporate	—		695,490		—		—		695,490
Municipal	—		58,930		—		—		58,930
Residential mortgage-backed	—		29,439		—		—		29,439
Commercial mortgage-backed	—		211,186		—		—		211,186
Asset-backed	—		97,565		—		—		97,565
Other assets	—		14,554		—		—		14,554
	$	—	$	1,179,940	$	—	$	—	$	1,179,940

Reinsurance balances recoverable:	$	—	$	—	$	542,224	$	—	$	542,224

Other Assets:
Derivative Instruments	$	—	$	319	$	—	$	—	$	319
	$	—	$	319	$	—	$	—	$	319

Losses and LAE:	$	—	$	—	$	1,794,669	$	—	$	1,794,669

Other Liabilities:
Derivative Instruments	$	—	$	7,246	$	—	$	—	$	7,246
	$	—	$	7,246	$	—	$	—	$	7,246



	June 30, 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	$	—	$	538,552	$	—	$	—	$	538,552
Non-U.S. government	—		1,056,161		—		—		1,056,161
Corporate	—		3,846,527		27,823		—		3,874,350
Municipal	—		93,051		—		—		93,051
Residential mortgage-backed	—		306,043		—		—		306,043
Commercial mortgage-backed	—		387,675		15,326		—		403,001
Asset-backed	—		539,880		46,608		—		586,488
	$	—	$	6,767,889	$	89,757	$	—	$	6,857,646
Equities:
Equities — U.S.	$	86,407	$	1,833	$	2,016	$	—	$	90,256
Equities — International	38,039		2,109		—		—		40,148
	$	124,446	$	3,942	$	2,016	$	—	$	130,404
Other investments:
Private equities and private equity funds	$	—	$	—	$	—	$	252,965	$	252,965
Fixed income funds	—		322,069		—		20,097		342,166
Hedge funds	—		—		—		670,963		670,963
Equity funds	—		115,794		—		271,696		387,490
CLO equities	—		—		53,840		—		53,840
CLO equity fund	—		—		—		40,864		40,864
Private credit funds	—		—		—		14,319		14,319
Call options on equities	—		4,998		—		—		4,998
Other	—		—		314		414		728
	$	—	$	442,861	$	54,154	$	1,271,318	$	1,768,333
Total Investments	$	124,446	$	7,214,692	$	145,927	$	1,271,318	$	8,756,383
Funds Held - Directly Managed:
U.S. government and agency	$	—	$	87,017	$	—	$	—	$	87,017
Non-U.S. government	—		22,625		—		—		22,625
Corporate	—		672,437		—		—		672,437
Municipal	—		58,933		—		—		58,933
Residential mortgage-backed	—		60,260		—		—		60,260
Commercial mortgage-backed	—		221,133		—		—		221,133
Asset-backed	—		97,840		499		—		98,339
Other assets	—		9,152		—		—		9,152
	$	—	$	1,229,397	$	499	$	—	$	1,229,896

Reinsurance balances recoverable:	$	—	$	—	$	837,373	$	—	$	837,373

Other Assets:
Derivative Instruments	$	—	$	12,317	$	—	$	—	$	12,317
	$	—	$	12,317	$	—	$	—	$	12,317

Losses and LAE:	$	—	$	—	$	3,221,366	$	—	$	3,221,366

Other Liabilities:
Derivative Instruments	$	—	$	77	$	—	$	—	$	77
	$	—	$	77	$	—	$	—	$	77

Reconciliation for Assets Measured at Fair Value on a Recurring Basis



	Three Months Ended June 30, 2018
	Corporate			Residential mortgage-backed			Commercial mortgage-backed			Asset-backed			Equities - U.S.		Other Investments			Total
Beginning fair value	$	86,027		$	1,907		$	17,634		$	21,997		$	—	$	56,659		$	184,224
Purchases	971			—			—			28,291			2,000		622			31,884
Sales	(53,873		)	(36		)	(1,150		)	(8		)	—		(600		)	(55,667		)
Total realized and unrealized gains (losses)	(258		)	(8		)	(31		)	(117		)	16		(2,527		)	(2,925		)
Transfer into Level 3 from Level 2	—			—			—			2,079			—		—			2,079
Transfer out of Level 3 into Level 2	(5,044		)	(1,863		)	(1,127		)	(5,634		)	—		—			(13,668		)
Ending fair value	$	27,823		$	—		$	15,326		$	46,608		$	2,016	$	54,154		$	145,927



	Three Months Ended June 30, 2017
	Corporate			Residential mortgage-backed			Commercial mortgage-backed			Asset-backed			Equities - U.S.		Other Investments			Total
Beginning fair value	$	56,179		$	—		$	24,852		$	29,082		$	—	$	69,627		$	179,740
Purchases	6,679			711			10,347			—			—		292			18,029
Sales	(6,461		)	(5		)	(734		)	(7,118		)	—		—			(14,318		)
Total realized and unrealized gains (losses)	191			(13		)	436			(72		)	—		(450		)	92
Transfer into Level 3 from Level 2	3,378			—			4,015			31,775			—		—			39,168
Transfer out of Level 3 into Level 2	(5,610		)	—			(16,051		)	(13,234		)	—		(12,350		)	(47,245		)
Ending fair value	$	54,356		$	693		$	22,865		$	40,433		$	—	$	57,119		$	175,466



	Six Months Ended June 30, 2018
	Corporate			Residential mortgage-backed			Commercial mortgage-backed			Asset-backed			Equities - U.S.		Other Investments			Total
Beginning fair value	$	67,178		$	3,080		$	21,494		$	27,892		$	—	$	57,079		$	176,723
Purchases	11,803			—			1,803			29,591			2,000		752			45,949
Sales	(60,910		)	(1,184		)	(1,727		)	(3,812		)	—		(600		)	(68,233		)
Total realized and unrealized gains (losses)	(63		)	(33		)	52			(71		)	16		(3,077		)	(3,176		)
Transfer into Level 3 from Level 2	15,259			—			4,897			2,079			—		—			22,235
Transfer out of Level 3 into Level 2	(5,444		)	(1,863		)	(11,193		)	(9,071		)	—		—			(27,571		)
Ending fair value	$	27,823		$	—		$	15,326		$	46,608		$	2,016	$	54,154		$	145,927



	Six Months Ended June 30, 2017
	Corporate			Residential mortgage-backed			Commercial mortgage-backed			Asset-backed			Equities - U.S.		Other Investments			Total
Beginning fair value	$	74,534		$	—		$	12,213		$	14,692		$	—	$	76,878		$	178,317
Purchases	15,568			711			10,347			1,380			—		292			28,298
Sales	(25,117		)	(5		)	(734		)	(7,361		)	—		—			(33,217		)
Total realized and unrealized gains (losses)	650			(13		)	331			209			—		(7,701		)	(6,524		)
Transfer into Level 3 from Level 2	4,945			—			17,916			49,336			—		—			72,197
Transfer out of Level 3 into Level 2	(16,224		)	—			(17,208		)	(17,823		)	—		(12,350		)	(63,605		)
Ending fair value	$	54,356		$	693		$	22,865		$	40,433		$	—	$	57,119		$	175,466

Reconciliation for Liabilities Measured at Fair Value on a Recurring Basis



	Three Months Ended June 30, 2018						Three Months Ended June 30, 2017
	Liability for losses and LAE			Reinsurance balances recoverable			Liability for losses and LAE			Reinsurance balances recoverable
Beginning fair value	$	3,519,453		$	888,736		$	1,924,829		$	551,253
Assumed business	—			—			—			—
Changes in nominal amounts:
Net incurred losses and LAE	(48,899		)	3,860			(26,407		)	(2,095		)
Paid losses	(145,676		)	(35,389		)	(39,686		)	(4,488		)
Changes in fair value:
Discounted cash flows	29,141			2,067			(3,354		)	5,947
Risk margin	(11,595		)	(1,754		)	(4,563		)	(632		)
Effect of exchange rate movements	(121,058		)	(20,147		)	41,478			4,774
Ending fair value	$	3,221,366		$	837,373		$	1,892,297		$	554,759



	Six Months Ended June 30, 2018						Six Months Ended June 30, 2017
	Liability for losses and LAE			Reinsurance balances recoverable			Liability for losses and LAE			Reinsurance balances recoverable
Beginning fair value	$	1,794,669		$	542,224		$	—		$	—
Assumed business	1,890,061			372,780			1,966,843			565,824
Changes in nominal amounts:
Net incurred losses and LAE	(55,196		)	2,384			(32,645		)	(2,095		)
Paid losses	(304,048		)	(53,535		)	(100,053		)	(21,494		)
Changes in fair value:
Discounted cash flows	(20,863		)	(13,882		)	17,013			8,413
Risk margin	(18,746		)	(2,719		)	(9,052		)	(1,702		)
Effect of exchange rate movements	(64,511		)	(9,879		)	50,191			5,813
Ending fair value	$	3,221,366		$	837,373		$	1,892,297		$	554,759

Quantitative Information



		June 30, 2018	December 31, 2017
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)	5.0%	5.0%
Internal model	Weighted average cost of capital (U)	8.5%	8.5%
Internal model	Duration - liability (U)	7.95 years	11.41 years
Internal model	Duration - reinsurance balances recoverable (U)	8.94 years	11.66 years

Derivative and Hedging Instruments (Tables)

6 Months Ended

Jun. 30, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

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

The following table presents the net gains and losses that were deferred in the CTA account, which is a component of AOCI in shareholders' equity, related to our non-derivative hedges for the three and six months ended June 30, 2018 and 2017.



	Amount of Gains (Losses) Deferred in AOCI					Amount of Gains (Losses) Deferred in AOCI
	Three Months Ended June 30,					Six Months Ended June 30,
	2018		2017			2018		2017
Net gains (losses) on qualifying non-derivative hedges	$	3,684	$	(5,370	)	$	2,448	$	(6,495	)



	June 30, 2018						December 31, 2017
			Fair Value						Fair Value
	Gross Notional Amount		Assets		Liabilities		Gross Notional Amount		Assets		Liabilities
Foreign exchange forward - AUD	$	27,358	$	571	$	—	$	32,810	$	—	$	965
Foreign exchange forward - CAD	—		—		—		27,141		11		512
Total qualifying hedges	$	27,358	$	571	$	—	$	59,951	$	11	$	1,477



	Amount of Gains (Losses) Deferred in AOCI					Amount of Gains (Losses) Deferred in AOCI
	Three Months Ended June 30,					Six Months Ended June 30,
	2018		2017			2018		2017
Foreign exchange forward - AUD	$	1,078	$	(1,007	)	$	1,608	$	(562	)
Foreign exchange forward - CAD	—		(668		)	—		(116		)
Net gains (losses) on qualifying derivative hedges	$	1,078	$	(1,675	)	$	1,608	$	(678	)



	June 30, 2018						December 31, 2017
			Fair Value						Fair Value
	Gross Notional Amount		Assets		Liabilities		Gross Notional Amount		Assets		Liabilities
Foreign exchange forward - AUD	$	46,582	$	833	$	—	$	57,028	$	—	$	1,002
Foreign exchange forward - GBP	218,228		5,700		—		207,323		262		4,312
Foreign exchange forward - EUR	32,696		958		—		19,235		46		455
Foreign exchange forward - CAD	114,873		4,255		77		—		—		—
Total non-qualifying hedges	$	412,379	$	11,746	$	77	$	283,586	$	308	$	5,769



	Gains (Losses) on non-qualifying hedges included in net earnings
	Three Months Ended June 30,					Six Months Ended June 30,
	2018		2017			2018		2017
Foreign exchange forward - AUD	$	1,514	$	—		$	2,496	$	—
Foreign exchange forward - GBP	11,077		(611		)	4,235		(740		)
Foreign exchange forward - EUR	1,624		(354		)	1,357		(563		)
Foreign exchange forward - CAD	5,207		—			7,247		$	—
Net gains (losses) on non-qualifying hedges	$	19,422	$	(965	)	$	15,335	$	(1,303	)

- 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
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-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
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 2
-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
-Topic 815
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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
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
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Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=109980867&loc=d3e41641-113959

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-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 (Tables)

6 Months Ended

Jun. 30, 2018

Insurance [Abstract]

Summary of Reinsurance Reserves Recoverable and Uncollectible Reinsurance Balances Recoverable

The following tables provide the total reinsurance balances recoverable as at June 30, 2018 and December 31, 2017:



	June 30, 2018
	Non-life Run-off			Atrium			StarStone			Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	994,389		$	13,442		$	176,583		$	1,184,414
IBNR	650,106			24,036			191,925			866,067
Fair value adjustments	(13,176		)	775			(1,931		)	(14,332		)
Fair value adjustments - fair value option	(169,180		)	—			—			(169,180		)
Total reinsurance reserves recoverable	1,462,139			38,253			366,577			1,866,969
Paid losses recoverable	112,153			(648		)	16,337			127,842
	$	1,574,292		$	37,605		$	382,914		$	1,994,811
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	736,919		$	37,605		$	382,914		$	1,157,438
Reinsurance balances recoverable - fair value option	837,373			—			—			837,373
Total	$	1,574,292		$	37,605		$	382,914		$	1,994,811



	December 31, 2017
	Non-life Run-off			Atrium			StarStone			Other		Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	932,284		$	7,472		$	211,650		$	16	$	1,151,422
IBNR	590,154			31,476			242,620			—		864,250
Fair value adjustments	(12,970		)	1,583			(2,253		)	—		(13,640		)
Fair value adjustments - fair value option	(131,983		)	—			—			—		(131,983		)
Total reinsurance reserves recoverable	1,377,485			40,531			452,017			16		1,870,049
Paid losses recoverable	128,253			(451		)	23,179			—		150,981
	$	1,505,738		$	40,080		$	475,196		$	16	$	2,021,030
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	963,514		$	40,080		$	475,196		$	16	$	1,478,806
Reinsurance balances recoverable - fair value option	542,224			—			—			—		542,224
Total	$	1,505,738		$	40,080		$	475,196		$	16	$	2,021,030



	June 30, 2018								December 31, 2017
	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	$	1,623,739	$	59,230	$	1,564,509	3.6	%	$	1,252,887	$	51,115	$	1,201,772	4.1	%
Reinsurers rated below A-, secured	398,335		—		398,335		—	%	771,097		—		771,097		—	%
Reinsurers rated below A-, unsecured	133,633		101,666		31,967		76.1	%	162,259		114,098		48,161		70.3	%
Total	$	2,155,707	$	160,896	$	1,994,811	7.5	%	$	2,186,243	$	165,213	$	2,021,030	7.6	%



	Three Months Ended June 30,												Six Months Ended June 30,
	2018						2017						2018						2017
	Premiums Written			Premiums Earned			Premiums Written			Premiums Earned			Premiums Written			Premiums Earned			Premiums Written			Premiums Earned
Non-life Run-off
Gross	$	(938	)	$	23,188		$	1,222		$	4,710		$	6,442		$	36,298		$	2,205		$	6,008
Ceded	(723		)	(13,579		)	683			(1,345		)	(8,003		)	(19,511		)	(219		)	(2,567		)
Net	$	(1,661	)	$	9,609		$	1,905		$	3,365		$	(1,561	)	$	16,787		$	1,986		$	3,441
Atrium
Gross	$	41,560		$	39,795		$	34,565		$	35,822		$	91,002		$	79,469		$	80,978		$	72,042
Ceded	(6,977		)	(5,273		)	(3,238		)	(3,442		)	(14,925		)	(9,724		)	(7,732		)	(7,442		)
Net	$	34,583		$	34,522		$	31,327		$	32,380		$	76,077		$	69,745		$	73,246		$	64,600
StarStone
Gross	$	301,353		$	245,284		$	224,564		$	212,720		$	606,342		$	480,227		$	451,100		$	418,304
Ceded	(82,115		)	(61,663		)	(109,030		)	(94,169		)	(206,541		)	(169,780		)	(216,700		)	(184,345		)
Net	$	219,238		$	183,621		$	115,534		$	118,551		$	399,801		$	310,447		$	234,400		$	233,959
Other
Gross	$	975		$	980		$	582		$	1,657		$	2,012		$	2,030		$	2,082		$	3,214
Ceded	84			80			200			(382		)	37			22			(107		)	(745		)
Net	$	1,059		$	1,060		$	782		$	1,275		$	2,049		$	2,052		$	1,975		$	2,469
Total
Gross	$	342,950		$	309,247		$	260,933		$	254,909		$	705,798		$	598,024		$	536,365		$	499,568
Ceded	(89,731		)	(80,435		)	(111,385		)	(99,338		)	(229,432		)	(198,993		)	(224,758		)	(195,099		)
Total	$	253,219		$	228,812		$	149,548		$	155,571		$	476,366		$	399,031		$	311,607		$	304,469

Reinsurance Balances Recoverable by Reinsurer



	June 30, 2018										December 31, 2017
	Non-life Run-off		Atrium		StarStone		Total		% of Total		Non-life Run-off		Atrium		StarStone		Other		Total		% of Total
Top ten reinsurers	$	1,212,447	$	20,095	$	221,073	$	1,453,615	72.9	%	$	1,166,057	$	22,422	$	328,257	$	—	$	1,516,736	75.0	%
Other reinsurers > $1 million	347,782		16,796		159,009		523,587		26.2	%	322,722		16,631		144,336		—		483,689		24.0	%
Other reinsurers < $1 million	14,063		714		2,832		17,609		0.9	%	16,959		1,027		2,603		16		20,605		1.0	%
Total	$	1,574,292	$	37,605	$	382,914	$	1,994,811	100.0	%	$	1,505,738	$	40,080	$	475,196	$	16	$	2,021,030	100.0	%

Losses and Loss Adjustment Expenses (Tables)

6 Months Ended

Jun. 30, 2018

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 as at June 30, 2018 and December 31, 2017:



	June 30, 2018											December 31, 2017
	Non-life Run-off			Atrium		StarStone			Total			Non-life Run-off			Atrium		StarStone			Total
Outstanding losses	$	4,148,834		$	84,214	$	659,239		$	4,892,287		$	3,185,703		$	78,363	$	590,977		$	3,855,043
IBNR	3,084,112			142,320		668,845			3,895,277			2,903,927			150,508		599,221			3,653,656
Fair value adjustments	(119,937		)	5,364		(475		)	(115,048		)	(125,998		)	9,547		(555		)	(117,006		)
Fair value adjustments - fair value option	(440,024		)	—		—			(440,024		)	(314,748		)	—		—			(314,748		)
ULAE	352,765			2,334		20,796			375,895			300,588			2,455		18,100			321,143
Total	$	7,025,750		$	234,232	$	1,348,405		$	8,608,387		$	5,949,472		$	240,873	$	1,207,743		$	7,398,088

Reconciliation to Consolidated Balance Sheet:
Loss and loss adjustment expenses									$	5,387,021										$	5,603,419
Loss and loss adjustment expenses, at fair value									$	3,221,366										$	1,794,669
Total									$	8,608,387										$	7,398,088

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30,					Six Months Ended June 30,
	2018			2017		2018			2017
Balance as at beginning of period	$	8,986,070		$	7,760,587	$	7,398,088		$	5,987,867
Less: reinsurance reserves recoverable	2,217,033			1,895,491		1,870,033			1,388,193
Less: deferred charges on retroactive reinsurance	75,111			93,605		80,192			94,551
Net balance as at beginning of period	6,693,926			5,771,491		5,447,863			4,505,123
Net incurred losses and LAE:
Current period	153,860			81,400		249,014			166,945
Prior periods	(61,041		)	(71,780)		(136,661		)	(79,433		)
Total net incurred losses and LAE	92,819			9,620		112,353			87,512
Net paid losses:
Current period	(30,474		)	(16,173)		(38,577		)	(24,892		)
Prior periods	(290,491		)	(205,222)		(641,137		)	(454,944		)
Total net paid losses	(320,965		)	(221,395)		(679,714		)	(479,836		)
Effect of exchange rate movement	(139,561		)	69,231		(81,834		)	83,736
Acquired on purchase of subsidiaries	343,806			—		343,806			—
Assumed business	—			—		1,527,551			1,432,412
Net balance as at June 30	6,670,025			5,628,947		6,670,025			5,628,947
Plus: reinsurance reserves recoverable	1,866,969			1,923,962		1,866,969			1,923,962
Plus: deferred charges on retroactive reinsurance	71,393			88,475		71,393			88,475
Balance as at June 30	$	8,608,387		$	7,641,384	$	8,608,387		$	7,641,384

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the three and six months ended June 30, 2018 and 2017 for the Non-life Run-off segment:



	Three Months Ended June 30,					Six Months Ended June 30,
	2018		2017			2018		2017
Balance as at beginning of period	$	7,517,511	$	6,478,150		$	5,949,472	$	4,716,363
Less: reinsurance reserves recoverable	1,703,481		1,504,371			1,377,485		1,000,953
Less: deferred charges on retroactive insurance	75,111		93,605			80,192		94,551
Net balance as at beginning of period	5,738,919		4,880,174			4,491,795		3,620,859
Net incurred losses and LAE:
Current period	5,113		461			5,459		1,175
Prior periods	(75,247)		(64,863		)	(148,571)		(68,334		)
Total net incurred losses and LAE	(70,134)		(64,402		)	(143,112)		(67,159		)
Net paid losses:
Current period	(590)		(130		)	(591)		(371		)
Prior periods	(195,721)		(144,282		)	(448,304)		(300,613		)
Total net paid losses	(196,311)		(144,412		)	(448,895)		(300,984		)
Effect of exchange rate movement	(131,081)		56,887			(75,678)		74,512
Acquired on purchase of subsidiaries	150,825		—			150,825		—
Assumed business	—		—			1,517,283		1,401,019
Net balance as at June 30	5,492,218		4,728,247			5,492,218		4,728,247
Plus: reinsurance reserves recoverable	1,462,139		1,500,557			1,462,139		1,500,557
Plus: deferred charges on retroactive reinsurance	71,393		88,475			71,393		88,475
Balance as at June 30	$	7,025,750	$	6,317,279		$	7,025,750	$	6,317,279

Net incurred losses and LAE in the Non-life Run-off segment for the three months ended June 30, 2018 and 2017 were as follows:



	Three Months Ended June 30,
	2018								2017
	Prior Period			Current Period		Total			Prior Period			Current Period			Total
Net losses paid	$	195,721		$	590	$	196,311		$	144,282		$	130		$	144,412
Net change in case and LAE reserves	(125,416		)	1,052		(124,364		)	(127,393		)	(16		)	(127,409		)
Net change in IBNR reserves	(161,110		)	3,471		(157,639		)	(62,604		)	293			(62,311		)
Amortization of deferred charges	3,718			—		3,718			5,130			—			5,130
Increase (reduction) in estimates of net ultimate losses	(87,087		)	5,113		(81,974		)	(40,585		)	407			(40,178		)
Reduction in provisions for bad debt	—			—		—			(735		)	—			(735		)
Increase (reduction) in provisions for unallocated LAE	(9,311		)	—		(9,311		)	(10,989		)	54			(10,935		)
Amortization of fair value adjustments	3,918			—		3,918			678			—			678
Changes in fair value - fair value option	17,233			—		17,233			(13,232		)	—			(13,232		)
Net incurred losses and LAE	$	(75,247	)	$	5,113	$	(70,134	)	$	(64,863	)	$	461		$	(64,402	)

Net incurred losses and LAE in the Non-life Run-off segment for the six months ended June 30, 2018 and 2017 were as follows:



	Six Months Ended June 30,
	2018								2017
	Prior Period			Current Period		Total			Prior Period			Current Period			Total
Net losses paid	$	448,304		$	591	$	448,895		$	300,613		$	371		$	300,984
Net change in case and LAE reserves	(248,908		)	1,058		(247,850		)	(210,527		)	(16		)	(210,543		)
Net change in IBNR reserves	(315,560		)	3,810		(311,750		)	(141,682		)	724			(140,958		)
Amortization of deferred charges	8,799			—		8,799			6,076			—			6,076
Increase (reduction) in estimates of net ultimate losses	(107,365		)	5,459		(101,906		)	(45,520		)	1,079			(44,441		)
Reduction in provisions for bad debt	—			—		—			(735		)	—			(735		)
Increase (reduction) in provisions for unallocated LAE	(24,263		)	—		(24,263		)	(25,354		)	96			(25,258		)
Amortization of fair value adjustments	6,065			—		6,065			2,025			—			2,025
Changes in fair value - fair value option	(23,008		)	—		(23,008		)	1,250			—			1,250
Net incurred losses and LAE	$	(148,571	)	$	5,459	$	(143,112	)	$	(68,334	)	$	1,175		$	(67,159	)

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the three and six months ended June 30, 2018 and 2017 for the Atrium segment:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Balance as at beginning of period	$	240,795		$	212,123		$	240,873		$	212,122
Less: reinsurance reserves recoverable	40,025			30,625			40,531			30,009
Net balance as at beginning of period	200,770			181,498			200,342			182,113
Net incurred losses and LAE:
Current period	19,175			14,858			36,481			29,279
Prior periods	(2,249		)	(6,669		)	(2,383		)	(8,602		)
Total net incurred losses and LAE	16,926			8,189			34,098			20,677
Net paid losses:
Current period	(10,465		)	(5,398		)	(17,619		)	(9,660		)
Prior periods	(8,882		)	(7,423		)	(19,258		)	(16,834		)
Total net paid losses	(19,347		)	(12,821		)	(36,877		)	(26,494		)
Effect of exchange rate movement	(2,370		)	2,031			(1,584		)	2,601
Net balance as at June 30	195,979			178,897			195,979			178,897
Plus: reinsurance reserves recoverable	38,253			29,749			38,253			29,749
Balance as at June 30	$	234,232		$	208,646		$	234,232		$	208,646

The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the three and six months ended June 30, 2018 and 2017 for our StarStone segment:



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Balance as at beginning of period	$	1,227,764		$	1,070,314		$	1,207,743		$	1,059,382
Less: reinsurance reserves recoverable	473,527			360,495			452,017			357,231
Net balance as at beginning of period	754,237			709,819			755,726			702,151
Net incurred losses and LAE:
Current period	129,572			66,081			207,074			136,491
Prior periods	16,455			(248		)	14,293			(2,497		)
Total net incurred losses and LAE	146,027			65,833			221,367			133,994
Net paid losses:
Current period	(19,419)			(10,645		)	(20,367		)	(14,861		)
Prior periods	(85,888)			(53,517		)	(173,575		)	(137,497		)
Total net paid losses	(105,307)			(64,162		)	(193,942		)	(152,358		)
Effect of exchange rate movement	(6,110		)	10,313			(4,572		)	6,623
Acquired on purchase of subsidiaries	192,981			—			192,981			—
Assumed business	—			—			10,268			31,393
Net balance as at June 30	981,828			721,803			981,828			721,803
Plus: reinsurance reserves recoverable	366,577			393,656			366,577			393,656
Balance as at June 30	$	1,348,405		$	1,115,459		$	1,348,405		$	1,115,459

Schedule of Incurred Losses

The tables below provide the net incurred losses and LAE by segment for the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30, 2018												Three Months Ended June 30, 2017
	Non-life Run-off			Atrium			StarStone			Total			Non-life Run-off			Atrium			StarStone			Total
Net losses paid	$	196,311		$	19,347		$	105,307		$	320,965		$	144,412		$	12,821		$	64,162		$	221,395
Net change in case and LAE reserves	(124,364		)	(3,442		)	25,841			(101,965		)	(127,409		)	(1,121		)	8,145			(120,385		)
Net change in IBNR reserves	(157,639		)	1,855			12,742			(143,042		)	(62,311		)	(3,542		)	(6,650		)	(72,503		)
Amortization of deferred charges	3,718			—			—			3,718			5,130			—			—			5,130
Increase (reduction) in estimates of net ultimate losses	(81,974		)	17,760			143,890			79,676			(40,178		)	8,158			65,657			33,637
Reduction in provisions for bad debt	—			—			—			—			(735		)	—			—			(735		)
Increase (reduction) in provisions for unallocated LAE	(9,311		)	2			2,238			(7,071		)	(10,935		)	(56		)	287			(10,704		)
Amortization of fair value adjustments	3,918			(836		)	(101		)	2,981			678			87			(111		)	654
Changes in fair value - fair value option	17,233			—			—			17,233			(13,232		)	—			—			(13,232		)
Net incurred losses and LAE	$	(70,134	)	$	16,926		$	146,027		$	92,819		$	(64,402	)	$	8,189		$	65,833		$	9,620



	Six Months Ended June 30, 2018												Six Months Ended June 30, 2017
	Non-life Run-off			Atrium			StarStone			Total			Non-life Run-off			Atrium			StarStone			Total
Net losses paid	$	448,895		$	36,877		$	193,942		$	679,714		$	300,984		$	26,494		$	152,358		$	479,836
Net change in case and LAE reserves	(247,850		)	448			21,366			(226,036		)	(210,543		)	(527		)	(1,214		)	(212,284		)
Net change in IBNR reserves	(311,750		)	146			3,871			(307,733		)	(140,958		)	(5,346		)	(16,802		)	(163,106		)
Amortization of deferred charges	8,799			—			—			8,799			6,076			—			—			6,076
Increase (reduction) in estimates of net ultimate losses	(101,906		)	37,471			219,179			154,744			(44,441		)	20,621			134,342			110,522
Reduction in provisions for bad debt	—			—			—			—			(735		)	—			—			(735		)
Increase (reduction) in provisions for unallocated LAE	(24,263		)	2			2,430			(21,831		)	(25,258		)	(64		)	286			(25,036		)
Amortization of fair value adjustments	6,065			(3,375		)	(242		)	2,448			2,025			120			(634		)	1,511
Changes in fair value - fair value option	(23,008		)	—			—			(23,008		)	1,250			—			—			1,250
Net incurred losses and LAE	$	(143,112	)	$	34,098		$	221,367		$	112,353		$	(67,159	)	$	20,677		$	133,994		$	87,512

Net incurred losses and LAE in the Atrium segment for the three and six months ended June 30, 2018 and 2017 were as follows:



	Three Months Ended June 30,
	2018						2017
	Prior Period		Current Period		Total		Prior Period		Current Period		Total
Net losses paid	8,882		10,465		19,347		7,423		5,398		12,821
Net change in case and LAE reserves	(3,169	)	(273	)	(3,442	)	(2,007	)	886		(1,121	)
Net change in IBNR reserves	(7,128	)	8,983		1,855		(12,221	)	8,679		(3,542	)
Increase (reduction) in estimates of net ultimate losses	(1,415	)	19,175		17,760		(6,805	)	14,963		8,158
Increase (reduction) in provisions for unallocated LAE	2		—		2		49		(105	)	(56	)
Amortization of fair value adjustments	(836	)	—		(836	)	87		—		87
Net incurred losses and LAE	(2,249	)	19,175		16,926		(6,669	)	14,858		8,189



	Six Months Ended June 30,
	2018							2017
	Prior Period			Current Period		Total		Prior Period			Current Period		Total
Net losses paid	$	19,258		$	17,619	$	36,877	$	16,834		$	9,660	$	26,494
Net change in case and LAE reserves	(5,553)			6,001		448		(5,123)			4,596		(527)
Net change in IBNR reserves	(12,715)			12,861		146		(20,358)			15,012		(5,346)
Increase (reduction) in estimates of net ultimate losses	990			36,481		37,471		(8,647)			29,268		20,621
Increase (reduction) in provisions for unallocated LAE	2			—		2		(75)			11		(64)
Amortization of fair value adjustments	(3,375)			—		(3,375)		120			—		120
Net incurred losses and LAE	$	(2,383	)	$	36,481	$	34,098	$	(8,602	)	$	29,279	$	20,677

Net incurred losses and LAE in the StarStone segment for the three and six months ended June 30, 2018 and 2017 were as follows:



	Three Months Ended June 30,
	2018								2017
	Prior Period			Current Period		Total			Prior Period			Current Period		Total
Net losses paid	$	85,888		$	19,419	$	105,307		$	53,517		$	10,645	$	64,162
Net change in case and LAE reserves	(21,405		)	47,246		25,841			(16,621		)	24,766		8,145
Net change in IBNR reserves	(46,738		)	59,480		12,742			(35,828		)	29,178		(6,650		)
Increase in estimates of net ultimate losses	17,745			126,145		143,890			1,068			64,589		65,657
Increase (reduction) in provisions for unallocated LAE	(1,189		)	3,427		2,238			(1,205		)	1,492		287
Amortization of fair value adjustments	(101		)	—		(101		)	(111		)	—		(111		)
Net incurred losses and LAE	$	16,455		$	129,572	$	146,027		$	(248	)	$	66,081	$	65,833



	Six Months Ended June 30,
	2018								2017
	Prior Period			Current Period		Total			Prior Period			Current Period		Total
Net losses paid	$	173,575		$	20,367	$	193,942		$	137,497		$	14,861	$	152,358
Net change in case and LAE reserves	(35,622		)	56,988		21,366			(41,464		)	40,250		(1,214		)
Net change in IBNR reserves	(120,128		)	123,999		3,871			(94,765		)	77,963		(16,802		)
Increase in estimates of net ultimate losses	17,825			201,354		219,179			1,268			133,074		134,342
Increase (reduction) in provisions for unallocated LAE	(3,290		)	5,720		2,430			(3,131		)	3,417		286
Amortization of fair value adjustments	(242		)	—		(242		)	(634		)	—		(634		)
Net incurred losses and LAE	$	14,293		$	207,074	$	221,367		$	(2,497	)	$	136,491	$	133,994

Premiums Written and Earned (Tables)

6 Months Ended

Jun. 30, 2018

Insurance [Abstract]

Schedule of Net Premiums Written and Earned

The following tables provide the total reinsurance balances recoverable as at June 30, 2018 and December 31, 2017:



	June 30, 2018
	Non-life Run-off			Atrium			StarStone			Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	994,389		$	13,442		$	176,583		$	1,184,414
IBNR	650,106			24,036			191,925			866,067
Fair value adjustments	(13,176		)	775			(1,931		)	(14,332		)
Fair value adjustments - fair value option	(169,180		)	—			—			(169,180		)
Total reinsurance reserves recoverable	1,462,139			38,253			366,577			1,866,969
Paid losses recoverable	112,153			(648		)	16,337			127,842
	$	1,574,292		$	37,605		$	382,914		$	1,994,811
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	736,919		$	37,605		$	382,914		$	1,157,438
Reinsurance balances recoverable - fair value option	837,373			—			—			837,373
Total	$	1,574,292		$	37,605		$	382,914		$	1,994,811



	December 31, 2017
	Non-life Run-off			Atrium			StarStone			Other		Total
Recoverable from reinsurers on unpaid:
Outstanding losses	$	932,284		$	7,472		$	211,650		$	16	$	1,151,422
IBNR	590,154			31,476			242,620			—		864,250
Fair value adjustments	(12,970		)	1,583			(2,253		)	—		(13,640		)
Fair value adjustments - fair value option	(131,983		)	—			—			—		(131,983		)
Total reinsurance reserves recoverable	1,377,485			40,531			452,017			16		1,870,049
Paid losses recoverable	128,253			(451		)	23,179			—		150,981
	$	1,505,738		$	40,080		$	475,196		$	16	$	2,021,030
Reconciliation to Consolidated Balance Sheet:
Reinsurance balances recoverable	$	963,514		$	40,080		$	475,196		$	16	$	1,478,806
Reinsurance balances recoverable - fair value option	542,224			—			—			—		542,224
Total	$	1,505,738		$	40,080		$	475,196		$	16	$	2,021,030



	June 30, 2018								December 31, 2017
	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	$	1,623,739	$	59,230	$	1,564,509	3.6	%	$	1,252,887	$	51,115	$	1,201,772	4.1	%
Reinsurers rated below A-, secured	398,335		—		398,335		—	%	771,097		—		771,097		—	%
Reinsurers rated below A-, unsecured	133,633		101,666		31,967		76.1	%	162,259		114,098		48,161		70.3	%
Total	$	2,155,707	$	160,896	$	1,994,811	7.5	%	$	2,186,243	$	165,213	$	2,021,030	7.6	%



	Three Months Ended June 30,												Six Months Ended June 30,
	2018						2017						2018						2017
	Premiums Written			Premiums Earned			Premiums Written			Premiums Earned			Premiums Written			Premiums Earned			Premiums Written			Premiums Earned
Non-life Run-off
Gross	$	(938	)	$	23,188		$	1,222		$	4,710		$	6,442		$	36,298		$	2,205		$	6,008
Ceded	(723		)	(13,579		)	683			(1,345		)	(8,003		)	(19,511		)	(219		)	(2,567		)
Net	$	(1,661	)	$	9,609		$	1,905		$	3,365		$	(1,561	)	$	16,787		$	1,986		$	3,441
Atrium
Gross	$	41,560		$	39,795		$	34,565		$	35,822		$	91,002		$	79,469		$	80,978		$	72,042
Ceded	(6,977		)	(5,273		)	(3,238		)	(3,442		)	(14,925		)	(9,724		)	(7,732		)	(7,442		)
Net	$	34,583		$	34,522		$	31,327		$	32,380		$	76,077		$	69,745		$	73,246		$	64,600
StarStone
Gross	$	301,353		$	245,284		$	224,564		$	212,720		$	606,342		$	480,227		$	451,100		$	418,304
Ceded	(82,115		)	(61,663		)	(109,030		)	(94,169		)	(206,541		)	(169,780		)	(216,700		)	(184,345		)
Net	$	219,238		$	183,621		$	115,534		$	118,551		$	399,801		$	310,447		$	234,400		$	233,959
Other
Gross	$	975		$	980		$	582		$	1,657		$	2,012		$	2,030		$	2,082		$	3,214
Ceded	84			80			200			(382		)	37			22			(107		)	(745		)
Net	$	1,059		$	1,060		$	782		$	1,275		$	2,049		$	2,052		$	1,975		$	2,469
Total
Gross	$	342,950		$	309,247		$	260,933		$	254,909		$	705,798		$	598,024		$	536,365		$	499,568
Ceded	(89,731		)	(80,435		)	(111,385		)	(99,338		)	(229,432		)	(198,993		)	(224,758		)	(195,099		)
Total	$	253,219		$	228,812		$	149,548		$	155,571		$	476,366		$	399,031		$	311,607		$	304,469

Goodwill and Intangible Assets (Tables)

6 Months Ended

Jun. 30, 2018

Goodwill, Intangible Assets, Intangible Assets Arising from Insurance Contracts Acquired in Business Combination, and Deferred Charges Disclosure [Abstract]

Schedule of Goodwill and Intangible Assets

The gross carrying value, accumulated amortization and net carrying value of intangible assets by type and the deferred charge as at June 30, 2018 and December 31, 2017 were as follows:



	June 30, 2018									December 31, 2017
	Gross Carrying Value			Accumulated Amortization			Net Carrying Value			Gross Carrying Value			Accumulated Amortization			Net Carrying Value
Intangible assets with a definite life:
Fair value adjustments:
Losses and LAE liabilities	$	462,455		$	(347,407	)	$	115,048		$	462,455		$	(345,449	)	$	117,006
Reinsurance balances recoverable	(179,219		)	164,887			(14,332		)	(179,219		)	165,579			(13,640		)
Other Assets	(48,840		)	706			(48,134		)	(48,840		)	440			(48,400		)
Other Liabilities	85,845			(820		)	85,025			85,845			(418		)	85,427
Total	$	320,241		$	(182,634	)	$	137,607		$	320,241		$	(179,848	)	$	140,393
Other:
Distribution channel	$	20,000		$	(6,110	)	$	13,890		$	20,000		$	(5,444	)	$	14,556
Technology	15,000			(14,654		)	346			15,000			(13,210		)	1,790
Brand	7,000			(3,209		)	3,791			7,000			(2,859		)	4,141
Total	$	42,000		$	(23,973	)	$	18,027		$	42,000		$	(21,513	)	$	20,487
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

Deferred charges on retroactive reinsurance	$	278,643		$	(207,250	)	$	71,393		$278,643			$	(198,451	)	$80,192

The following table presents a reconciliation of the beginning and ending goodwill, intangible assets and the deferred charges during the six months ended June 30, 2018:



	Goodwill		Intangible assets with a definite life - Other			Intangible assets with an indefinite life		Total			Intangible assets with a definite life - FVA			Other assets - Deferred Charges
Balance as at January 1, 2018	$	73,071	$	20,487		$	87,031	$	180,589		$	140,393		$	80,192
Acquired during the period	41,736		—			—		41,736			—			—
Amortization	—		(2,460		)	—		(2,460		)	(2,786		)	(8,799		)
Balance as at June 30, 2018	$	114,807	$	18,027		$	87,031	$	219,865		$	137,607		$	71,393

Debt Obligations (Tables)

6 Months Ended

Jun. 30, 2018

Debt Disclosure [Abstract]

Amounts of Loans Payable Outstanding, and Accrued Interest

Debt obligations as at June 30, 2018 and December 31, 2017 were as follows:



Facility	Origination Date	Term	June 30, 2018			December 31, 2017
Senior Notes	March 10, 2017	5 years	$	350,000		$	350,000
Less: Unamortized debt issuance costs			(2,285		)	(2,484		)
Total Senior Notes			347,715			347,516
EGL Revolving Credit Facility	September 16, 2014	5 years	91,895			225,110
EGL Term Loan Facility	November 18, 2016	3 years	—			74,063
Total debt obligations			$	439,610		$	646,689

- 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
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-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
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-SubTopic 10
-Section 50
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-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)

6 Months Ended

Jun. 30, 2018

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 as at June 30, 2018 and December 31, 2017:



	Six Months Ended June 30, 2018			Year Ended December 31, 2017
Balance at beginning of period	$	479,606		$	454,522
Dividends paid	—			(27,458		)
Net earnings (losses) attributable to RNCI	(8,021		)	19,619
Accumulated other comprehensive earnings (losses) attributable to RNCI	(381		)	1,945
Change in redemption value of RNCI	(111		)	30,978
Balance at end of period	$	471,093		$	479,606

Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2018

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 share for the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30,					Six Months Ended June 30,
	2018		2017			2018			2017
Numerator:
Net earnings (loss) from continuing operations	$	8,244	$	95,057		$	(32,966	)	$	149,366
Net loss from discontinued operations	—		(4,871		)	—			(4,500		)
Net earnings (loss) attributable to Enstar Group Limited	8,244		90,186			(32,966		)	144,866
Denominator:
Weighted average ordinary shares outstanding — basic	20,462,788		19,387,650			19,938,815			19,381,225
Effect of dilutive securities:
Share-based compensation plans	128,232		53,720			122,471			54,182
Warrants	80,212		70,059			79,081			70,670
Weighted average ordinary shares outstanding — diluted	20,671,232		19,511,429			20,140,367			19,506,077
Earnings (losses) per share attributable to Enstar Group Limited:
Basic:
Net earnings (loss) from continuing operations	$	0.40	$	4.90		$	(1.65	)	$	7.71
Net loss from discontinued operations	—		(0.25		)	$	—		$	(0.23	)
Net earnings (loss) per ordinary share	$	0.40	$	4.65		$	(1.65	)	$	7.48
Diluted⁽¹⁾:
Net earnings (loss) from continuing operations	$	0.40	$	4.87		$	(1.65	)	$	7.66
Net loss from discontinued operations	—		(0.25		)	$	—		$	(0.23	)
Net earnings (loss) per ordinary share	$	0.40	$	4.62		$	(1.65	)	$	7.43

Share-Based Compensation and Pensions (Tables)

6 Months Ended

Jun. 30, 2018

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, employee share purchase plan, and pension plans for the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017

Share-based Compensation Expense	$	4,454	$	6,155	$	10,519	$	9,979

Employee Share Purchase Plan	$	127	$	58	$	210	$	166

Pension Expense	$	3,184	$	3,182	$	5,822	$	5,485

Related Party Transactions (Tables)

6 Months Ended

Jun. 30, 2018

Schedule of Related Party Transactions

As at June 30, 2018 and December 31, 2017, the RNCI on our balance sheet relating to these Trident co-investment transactions was as follows:



	June 30, 2018	December 31, 2017
Redeemable Noncontrolling Interest	451,490	459,649

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:



	June 30, 2018		December 31, 2017
Investments in funds managed by Stone Point	$	366,279	$	255,905
Investments in registered investment companies affiliated with entities owned by Trident	40,422		22,060
Investments managed by Eagle Point Credit Management and PRIMA Capital Advisors	216,695		183,448
Investments in funds managed by Sound Point Capital	20,097		27,429
Investments in CLO equity securities with Sound Point Capital as collateral manager	17,137		17,760
Separate account managed by Sound Point Capital	65,182		63,572

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 June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Net unrealized gains on funds managed by Stone Point	$	3,778		$	4,682		$	2,252		$	11,650
Net unrealized gains (losses) on registered investment companies affiliated with entities owned by Trident	344			(171		)	6,549			5,037
Interest income on registered investment companies affiliated with entities owned by Trident	828			771			1,910			1,274
Management fees on investments managed by Eagle Point Credit Management and PRIMA Capital Advisors	(227		)	(151		)	(454		)	(291		)
Net unrealized gains (losses) on investments in funds managed by Sound Point Capital	291			433			(238		)	794
Net unrealized (losses) on investments in CLO equity securities with Sound Point Capital as collateral manager	(392		)	(383		)	(623		)	(2,494		)
Interest income on investments in CLO equity securities with Sound Point Capital as collateral manager	1,179			1,292			2,489			2,479
Management fees on separate account managed by Sound Point Capital	(80		)	(81		)	(161		)	(153		)

The reinsurance recoverable on our consolidated balance sheet as at June 30, 2018 and December 31, 2017 was as follows:



	June 30, 2018		December 31, 2017
Reinsurance balances recoverable	$	6,992	$	7,003

Our consolidated balance sheets as at December 31, 2017 included the following balances related to transactions between us and KaylaRe and KaylaRe Ltd.:



	December 31, 2017
Reinsurance balances recoverable	$	357,355
Prepaid reinsurance premiums	116,356
Funds held	174,181
Insurance and reinsurance balances payable	232,884
Ceded acquisition costs	36,070

Our consolidated statement of earnings as at June 30, 2018 and June 30, 2017 included the following balances related to transactions between us and KaylaRe and KaylaRe Ltd.:



	Six Months Ended June 30,
	2018		2017
Fee income due to Enstar Limited	$	1,453	$	—

Transactions under KaylaRe-StarStone QS:
Ceded premium earned	52,651		113,354
Net incurred losses	31,654		60,156
Acquisition costs	18,774		45,373

Transactions under Fitzwilliam reinsurance agreement:
Profit Commission	—		7,816

Our consolidated balance sheet as at June 30, 2018 and December 31, 2017 included the following balances related to transactions between us and Hillhouse and its affiliated entities:



	June 30, 2018		December 31, 2017
Investments in funds managed by Hillhouse, held by equity method investments	$	—	$	456,660

Investment in funds managed by Hillhouse	703,986		—

Our consolidated statement of earnings as at June 30, 2018 and June 30, 2017 included the following balances related to transactions between us and Hillhouse and its affiliated entities:



	Three Months Ended June 30,		Six Months Ended June 30,
	2018		2018
Net unrealized gains	$	10,850	$	22,939

Our investment in the common and preferred shares of Monument, carried in other assets on our consolidated balance sheet, as at June 30, 2018 and December 31, 2017 was as follows:



	June 30, 2018		December 31, 2017
Carrying value	$	21,871	$	15,960

Our investment in the common shares of Clear Spring, carried in other assets on our consolidated balance sheet, as at June 30, 2018 and December 31, 2017 was as follows:



	June 30, 2018		December 31, 2017
Investment in Clear Spring	$	10,565	$	10,596

Our consolidated balance sheet as at June 30, 2018 and December 31, 2017 included the following balances related to transactions between us and Clear Spring:



	June 30, 2018		December 31, 2017
Balances under StarStone quota share:
Reinsurance balances recoverable	$	16,166	$	9,053
Prepaid insurance premiums	14,859		13,747
Ceded payable	15,925		13,964
Ceded acquisition costs	3,545		3,186

Balances under Cavello quota share:
Losses and LAE	554		—
Unearned reinsurance premiums	253		3,437
Funds held	1,400		5,095

Our consolidated statement of earnings as at June 30, 2018 and June 30, 2017 included the following balances related to transactions between us and Clear Spring:



	Three Months Ended June 30,					Six Months Ended June 30,
	2018			2017		2018		2017

Balances under StarStone quota share:
Ceded premium earned	$	7,636		$	—	$	14,638	$	—
Net incurred losses and LAE	3,044			—		8,606		—
Acquisition costs	2,129			—		3,911		—

Balances under Cavello quota share:
Premium earned	158			—		1,909		—
Net incurred losses and LAE	(629		)	—		761		—
Acquisition costs	91			—		555		—

Segment Information (Tables)

6 Months Ended

Jun. 30, 2018

Segment Reporting [Abstract]

Summary of Operations by Segment

The following tables set forth selected and unaudited condensed consolidated statement of earnings results by segment for the three and six months ended June 30, 2018 and 2017:



	Three Months Ended June 30, 2018
	Non-Life Run-Off			Atrium			StarStone			Other			Total
Gross premiums written	$	(938	)	$	41,560		$	301,353		$	975		$	342,950

Net premiums written	$	(1,661	)	$	34,583		$	219,238		$	1,059		$	253,219

Net premiums earned	$	9,609		$	34,522		$	183,621		$	1,060		$	228,812
Net incurred losses and LAE	70,134			(16,926		)	(146,027		)	—			(92,819		)
Life and Annuity Policy Benefits	—			—			—			160			160
Acquisition costs	(3,214		)	(12,716		)	(37,271		)	(133		)	(53,334		)
Operating expenses	(38,378		)	(4,130		)	(34,142		)	—			(76,650		)
Underwriting income (loss)	38,151			750			(33,819		)	1,087			6,169
Net investment income	57,291			1,285			8,745			(852		)	66,469
Net realized and unrealized losses	(46,027		)	(680		)	(3,181		)	(4,530		)	(54,418		)
Fees and commission income	4,487			3,865			—			—			8,352
Other income (expense)	6,311			56			(600		)	527			6,294
Corporate expenses	(13,387		)	(1,838		)	—			(10,737		)	(25,962		)
Interest income (expense)	(10,081		)	—			(6		)	1,165			(8,922		)
Net foreign exchange gains (losses)	6,958			(47		)	(1,573		)	181			5,519
EARNINGS (LOSS) BEFORE INCOME TAXES	43,703			3,391			(30,434		)	(13,159		)	3,501
INCOME TAXES	(1,219		)	(739		)	(1,688		)	—			(3,646		)
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	42,484			2,652			(32,122		)	(13,159		)	(145		)
Net loss (earnings) attributable to noncontrolling interest	(1,094		)	(1,121		)	10,604			—			8,389
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$	41,390		$	1,531		$	(21,518	)	$	(13,159	)	$	8,244

Underwriting ratios:
Loss ratio⁽¹⁾				49.0		%	79.5		%
Acquisition expense ratio ⁽¹⁾				36.8		%	20.3		%
Operating expense ratio⁽¹⁾				12.0		%	18.6		%
Combined ratio ⁽¹⁾				97.8		%	118.4		%

⁽¹⁾Refer to "Underwriting Ratios" for a description of how these ratios are calculated.



	Six Months Ended June 30, 2018
	Non-Life Run-Off			Atrium			StarStone			Other			Total
Gross premiums written	$	6,442		$	91,002		$	606,342		$	2,012		$	705,798

Net premiums written	$	(1,561	)	$	76,077		$	399,801		$	2,049		$	476,366

Net premiums earned	$	16,787		$	69,745		$	310,447		$	2,052		$	399,031
Net incurred losses and LAE	143,112			(34,098		)	(221,367		)	—			(112,353		)
Life and Annuity Policy Benefits	—			—			—			206			206
Acquisition costs	(4,684		)	(24,781		)	(53,696		)	(281		)	(83,442		)
Operating expenses	(76,781		)	(8,307		)	(68,699		)	—			(153,787		)
Underwriting income (loss)	78,434			2,559			(33,315		)	1,977			49,655
Net investment income	108,942			2,470			16,446			4,930			132,788
Net realized and unrealized gains (losses)	(172,323		)	(2,083		)	(16,139		)	(6,903		)	(197,448		)
Fees and commission income	9,385			7,298			—			—			16,683
Other income (expense)	23,566			120			(549		)	(203		)	22,934
Corporate expenses	(22,020		)	(2,313		)	—			(19,752		)	(44,085		)
Interest income (expense)	(18,611		)	—			(547		)	2,225			(16,933		)
Net foreign exchange gains (losses)	(219		)	(1,000		)	(478		)	1,348			(349		)
EARNINGS (LOSS) BEFORE INCOME TAXES	7,154			7,051			(34,582		)	(16,378		)	(36,755		)
INCOME TAXES	(102		)	(1,019		)	(2,686		)	(11		)	(3,818		)
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	7,052			6,032			(37,268		)	(16,389		)	(40,573		)
Net loss (earnings) attributable to noncontrolling interest	(2,523		)	(2,532		)	12,662			—			7,607
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$	4,529		$	3,500		$	(24,606	)	$	(16,389	)	$	(32,966	)

Underwriting ratios:
Loss ratio⁽¹⁾				48.9		%	71.3		%
Acquisition expense ratio ⁽¹⁾				35.5		%	17.3		%
Operating expense ratio⁽¹⁾				11.9		%	22.1		%
Combined ratio ⁽¹⁾				96.3		%	110.7		%



	Three Months Ended June 30, 2017
	Non-Life Run-Off			Atrium			StarStone			Other			Total
Gross premiums written	$	1,222		$	34,565		$	224,564		$	582		$	260,933

Net premiums written	$	1,905		$	31,327		$	115,534		$	782		$	149,548

Net premiums earned	$	3,365		$	32,380		$	118,551		$	1,275		$	155,571
Net incurred losses and LAE	64,402			(8,189		)	(65,833		)	—			(9,620		)
Life and Annuity Policy Benefits	—			—			—			(4,289		)	(4,289		)
Acquisition costs	946			(12,057		)	(17,698		)	(1,546		)	(30,355		)
Operating expenses	(31,668		)	(6,313		)	(32,950		)	—			(70,931		)
Underwriting income (loss)	37,045			5,821			2,070			(4,560		)	40,376
Net investment income	39,572			861			7,189			1,795			49,417
Net realized and unrealized gains (losses)	50,556			474			7,209			(6,362		)	51,877
Fees and commission income (expense)	10,817			8,070			—			(220		)	18,667
Other income	10,769			50			33			4			10,856
Corporate expenses	(22,793		)	(3,637		)	—			(9,129		)	(35,559		)
Interest income (expense)	(7,646		)	(265		)	(644		)	982			(7,573		)
Net foreign exchange losses	(2,160		)	(3,480		)	(815		)	(667		)	(7,122		)
Loss on sale of subsidiary	—			—			—			(9,609		)	(9,609		)
EARNINGS (LOSS) BEFORE INCOME TAXES	116,160			7,894			15,042			(27,766		)	111,330
INCOME TAXES	(3,679		)	(368		)	(679		)	(5		)	(4,731		)
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	112,481			7,526			14,363			(27,771		)	106,599
NET LOSS FROM DISCONTINUED OPERATIONS, NET OF INCOME TAX EXPENSE	—			—			—			(4,871		)	(4,871		)
NET EARNINGS (LOSS)	112,481			7,526			14,363			(32,642		)	101,728
Net earnings attributable to noncontrolling interest	(2,621		)	(3,087		)	(5,834		)	—			(11,542		)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$	109,860		$	4,439		$	8,529		$	(32,642	)	$	90,186

Underwriting ratios:
Loss ratio⁽¹⁾				25.3		%	55.5		%
Acquisition expense ratio ⁽¹⁾				37.2		%	14.9		%
Operating expense ratio⁽¹⁾				19.5		%	27.9		%
Combined ratio ⁽¹⁾				82.0		%	98.3		%

⁽¹⁾Refer to "Underwriting Ratios" for a description of how these ratios are calculated.



	Six Months Ended June 30, 2017
	Non-Life Run-Off			Atrium			StarStone			Other			Total
Gross premiums written	$	2,205		$	80,978		$	451,100		$	2,082		$	536,365

Net premiums written	$	1,986		$	73,246		$	234,400		$	1,975		$	311,607

Net premiums earned	$	3,441		$	64,600		$	233,959		$	2,469		$	304,469
Net incurred losses and LAE	67,159			(20,677		)	(133,994		)	—			(87,512		)
Life and Annuity Policy Benefits	—			—			—			(3,988		)	(3,988		)
Acquisition costs	546			(22,829		)	(28,312		)	(581		)	(51,176		)
Operating expenses	(61,110		)	(9,720		)	(66,971		)	—			(137,801		)
Underwriting income (loss)	10,036			11,374			4,682			(2,100		)	23,992
Net investment income	75,301			1,985			12,638			8,232			98,156
Net realized and unrealized gains (losses)	102,114			892			13,908			(6,518		)	110,396
Fees and commission income (expense)	19,540			11,442			1,166			(1,567		)	30,581
Other income	22,697			119			79			159			23,054
Corporate expenses	(46,142		)	(7,441		)	—			(17,574		)	(71,157		)
Interest income (expense)	(14,327		)	(536		)	(1,266		)	1,688			(14,441		)
Net foreign exchange losses	(2,937		)	(4,312		)	(2,708		)	(880		)	(10,837		)
Loss on sale of subsidiary	—			—			—			(9,609		)	(9,609		)
EARNINGS (LOSS) BEFORE INCOME TAXES	166,282			13,523			28,499			(28,169		)	180,135
INCOME (TAXES) BENEFIT	(4,639		)	(724		)	3,570			(9		)	(1,802		)
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	161,643			12,799			32,069			(28,178		)	178,333
NET LOSS FROM DISCONTINUED OPERATIONS, NET OF INCOME TAX EXPENSE	—			—			—			(4,500		)	(4,500		)
NET EARNINGS (LOSS)	161,643			12,799			32,069			(32,678		)	173,833
Net earnings attributable to noncontrolling interest	(10,630		)	(5,250		)	(13,087		)	—			(28,967		)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$	151,013		$	7,549		$	18,982		$	(32,678	)	$	144,866

Underwriting ratios:
Loss ratio⁽¹⁾				32.0		%	57.3		%
Acquisition expense ratio ⁽¹⁾				35.3		%	12.1		%
Operating expense ratio⁽¹⁾				15.1		%	28.6		%
Combined ratio ⁽¹⁾				82.4		%	98.0		%

⁽¹⁾Refer to "Underwriting Ratios" for a description of how these ratios are calculated.

Summary of Company's Assets by Segment



	June 30,			December 31,
	2018			2017
Assets by Segment:
Non-life Run-off	$	11,997,250		$	10,368,105
Atrium	584,631			556,637
StarStone	3,113,207			3,128,725
Other	(491,876		)	(447,045		)
Total assets	$	15,203,212		$	13,606,422

Significant Accounting Policies (Details) - Retained Earnings - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principle	$ (1,573)		$ 4,882
Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principle		$ (1,600)

Acquisitions - Additional Information (Detail) $ / shares in Units, $ in Thousands		3 Months Ended	6 Months Ended
	May 14, 2018 USD ($) $ / shares shares	Jun. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Excess of purchase price over fair value of net assets acquired		$ 114,807	$ 114,807	$ 73,071
KaylaRe
Business Acquisition [Line Items]
Excess of purchase price over fair value of net assets acquired	$ 41,736
Shares issued (in shares) \| shares	2,007,017
Acquisition purchase price, per share (in dollars per share) \| $ / shares	$ 206.65
Percent of voting interests acquired	51.80%
Price-to-book multiple	1.05
Equity interest in acquiree, remeasurement gain		16,007	16,000
Contractual preexisting relationships, remeasurement gain (loss)		$ (15,600)	$ 15,600
Ordinary Shares \| KaylaRe
Business Acquisition [Line Items]
Shares issued (in shares) \| shares	1,501,778
Series E Non-Voting Convertible Ordinary Shares \| KaylaRe
Business Acquisition [Line Items]
Shares issued (in shares) \| shares	505,239
KaylaRe
Business Acquisition [Line Items]
Ownership percentage		48.20%	48.20%

Acquisitions - Purchase Price and Fair Value of Assets Acquired (Detail) $ / shares in Units, $ in Thousands		3 Months Ended	6 Months Ended
	May 14, 2018 USD ($) $ / shares shares	Jun. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Purchase Price
Excess of purchase price over fair value of net assets acquired		$ 114,807	$ 114,807		$ 73,071
KaylaRe
Purchase Price
Fair value of Enstar ordinary shares issued	$ 414,750
Fair value of previously held equity method investment	336,137
Adjustment for the fair value of preexisting relationships	37,169
Total purchase price	788,056
Net assets acquired at fair value (excluding preexisting relationships)	746,320
Excess of purchase price over fair value of net assets acquired	$ 41,736
Fair Value of Enstar Ordinary Shares Issued
Number of Enstar Ordinary shares issued (in shares) \| shares	2,007,017
Closing price of Enstar Ordinary shares (in dollars per share) \| $ / shares	$ 206.65
Fair Value of Previously Held Equity Method Investment
Price-to-book multiple	1.05
Gain recognized on remeasurement of previously held equity method investment to fair value		$ 16,007	$ 16,000
KaylaRe
Fair Value of Previously Held Equity Method Investment
Carrying value of previously held equity method investment prior to the close of the transaction				$ 320,130	$ 309,800

Acquisitions - Loss On Settlement Of Contractual Preexisitng Relationships (Details) - USD ($) $ in Thousands	Jun. 30, 2018	May 14, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Funds held by reinsured companies	$ 259,432			$ 175,383
Deferred acquisition costs/Value of business acquired	128,781			64,984
TOTAL ASSETS	15,203,212			13,606,422
Losses and LAE	8,608,387		$ 8,986,070	7,398,088	$ 7,641,384	$ 7,760,587	$ 5,987,867
Unearned premiums	754,046			583,197
Insurance and reinsurance balances payable	354,100			236,697
Other liabilities	524,882			972,457
TOTAL LIABILITIES	10,804,971			9,980,868
NET ASSETS (LIABILITIES)	$ 3,927,148			$ 3,145,948
Carrying Value \| KaylaRe
Business Acquisition [Line Items]
Funds held by reinsured companies		$ 386,793
Deferred acquisition costs/Value of business acquired		33,549
TOTAL ASSETS		420,342
Losses and LAE		339,747
Unearned premiums		105,602
Insurance and reinsurance balances payable		25,897
Other liabilities		1,864
TOTAL LIABILITIES		473,110
NET ASSETS (LIABILITIES)		(52,768)
Fair Value \| KaylaRe
Business Acquisition [Line Items]
Funds held by reinsured companies		386,793
Deferred acquisition costs/Value of business acquired		40,268
TOTAL ASSETS		427,061
Losses and LAE		333,205
Unearned premiums		105,602
Insurance and reinsurance balances payable		23,559
Other liabilities		1,864
TOTAL LIABILITIES		464,230
NET ASSETS (LIABILITIES)		(37,169)
Fair Value Adjustments [Member] \| KaylaRe
Business Acquisition [Line Items]
Funds held by reinsured companies		0
Deferred acquisition costs/Value of business acquired		6,719
TOTAL ASSETS		6,719
Losses and LAE		(6,542)
Unearned premiums		0
Insurance and reinsurance balances payable		(2,338)
Other liabilities		0
TOTAL LIABILITIES		(8,880)
NET ASSETS (LIABILITIES)		$ 15,599

Acquisitions - Fair Values of Assets Acquired and Liabilities Assumed (Detail) - KaylaRe $ in Thousands	May 14, 2018 USD ($)
ASSETS
Fixed maturities, trading, at fair value	$ 126,393
Other investments	626,476
Total investments	752,869
Cash and cash equivalents	5,657
Premiums receivable	10,965
Deferred acquisition costs	275
Other assets	614
TOTAL ASSETS	770,380
LIABILITIES
Losses and LAE	4,059
Unearned premium	10,984
Insurance and reinsurance balances payable	13
Other liabilities	9,004
TOTAL LIABILITIES	24,060
NET ASSETS ACQUIRED AT FAIR VALUE	$ 746,320

Acquisitions - Results of Operations of Acquiree (Details) - KaylaRe $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Business Acquisition [Line Items]
Premiums earned	$ 5,381
Incurred losses and LAE	(4,960)
Acquisition costs	(135)
Underwriting income	286
Net investment income	791
Net unrealized gains	15,247
Earnings of acquiree since acquisition date	$ 16,324

Significant New Business - Additional Information (Detail) $ in Thousands, £ in Millions, $ in Millions								3 Months Ended		6 Months Ended
	Feb. 22, 2018 AUD ($)	Feb. 22, 2018 USD ($)	Feb. 16, 2018 AUD ($)	Feb. 16, 2018 USD ($)	Feb. 16, 2018 GBP (£)	Jan. 29, 2018 USD ($)	Jan. 29, 2018 GBP (£)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Feb. 22, 2018 USD ($)
Guarantor Obligations [Line Items]
Assumed business								$ 0	$ 0	$ 1,527,551	$ 1,432,412
Zurich
Guarantor Obligations [Line Items]
Assumed business	$ 359.4	$ 280,800
Reinsurance premium consideration	343.9	$ 268,700
Fair value adjustment on gross reserves	$ 15.5											$ 12,100
Neon
Guarantor Obligations [Line Items]
Assumed business				$ 546,300	£ 403.9
Reinsurance premium consideration			$ 445.1		329.1
Net insurance reserves assumed				462,600	£ 342.1
Fair value adjustment on gross reserves				20,600
Fair value adjustment of net reserves				$ 17,500
Novae
Guarantor Obligations [Line Items]
Assumed business						$ 1,163,200	£ 860.1
Reinsurance premium consideration						803,500	594.1
Net insurance reserves assumed						853,000	£ 630.7
Fair value adjustment on gross reserves						67,500
Fair value adjustment of net reserves						$ 49,500

Divestitures, Held-For-Sale Businesses and Discontinued Operations - Additional Information (Details) $ in Thousands, € in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 29, 2017 USD ($)	Aug. 29, 2017 USD ($)	Aug. 29, 2017 EUR (€)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale	$ 0		$ 0		$ 24,351
Liabilities held for sale	0		0		11,271
Net loss from discontinued operations	0	$ 4,871	0	$ 4,500
Loss on sale of subsidiary	0	9,609	0	9,609
Pavonia \| Discontinued operations, held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal, consideration							$ 120,000
Disposal, restricted investments					1,400
Assets held for sale					24,351
Liabilities held for sale					11,271
Net loss from discontinued operations		4,871		4,500
PLIC MI \| Discontinued operations, held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale	23,000		23,000
Liabilities held for sale	$ 10,000		$ 10,000
Laguna \| Disposed of by sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net loss from discontinued operations		$ 900		1,100
Loss on sale of subsidiary				$ 9,600	16,300
Cumulative CTA adjustment					$ 6,300
Scenario, Forecast \| PLIC MI \| Discontinued operations, held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal, consideration						$ 13,100
Monument \| Affiliated Entity \| Laguna \| Disposed of by sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal, consideration								$ 30,800	€ 25.6

Investments - Fair Values of Fixed Maturity Investments, Short-Term Investments and Equities Classified as Trading (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	$ 6,688,325
Equities, trading, at fair value	130,404	$ 106,603
Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	6,688,325	5,876,284
Trading securities	6,818,729	5,982,887
U.S. government and agency \| Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	536,132	554,036
Non-U.S. government \| Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	979,974	607,132
Corporate \| Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	3,787,366	3,363,060
Municipal \| Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	89,339	100,221
Residential mortgage-backed \| Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	306,025	288,713
Commercial mortgage-backed \| Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	403,001	421,548
Asset-backed \| Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	586,488	541,574
Equity securities \| Fair Value \| US
Debt and Equity Securities, FV-NI [Line Items]
Equities, trading, at fair value	90,256	106,363
Equity securities \| Fair Value \| Non-US
Debt and Equity Securities, FV-NI [Line Items]
Equities, trading, at fair value	40,148	240
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	160,200	152,400
Senior Secured Debt Securities
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	$ 13,900	$ 68,900

Divestitures, Held-For-Sale Businesses and Discontinued Operations - Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
ASSETS
Total assets held for sale	$ 0		$ 0		$ 24,351
LIABILITIES
Total liabilities held for sale	0		0		11,271
EXPENSES
NET LOSS FROM DISCONTINUED OPERATIONS	$ 0	$ (4,871)	$ 0	$ (4,500)
Pavonia \| Discontinued operations, held-for-sale
ASSETS
Equities, trading, at fair value					765
Cash and cash equivalents					6,314
Restricted cash and cash equivalents					13
Reinsurance balances recoverable					1,728
Other assets					269
Assets of businesses held for sale					29,859
Less: Accrual of loss on sale					(5,508)
Total assets held for sale					24,351
LIABILITIES
Policy benefits for life and annuity contracts					10,666
Other liabilities					605
Total liabilities held for sale					11,271
INCOME
Net premiums earned		13,605		27,930
Net investment income		10,277		20,306
Net realized and unrealized gains		1,154		2,776
Other income		395		755
Total income		25,431		51,767
EXPENSES
Life and annuity policy benefits		24,112		44,782
Acquisition costs		2,280		4,316
General and administrative expenses		3,718		6,775
Other expenses		0		(16)
Total expenses		30,110		55,857
LOSS BEFORE INCOME TAXES		(4,679)		(4,090)
INCOME TAXES		(192)		(410)
NET LOSS FROM DISCONTINUED OPERATIONS		$ (4,871)		(4,500)
Net Cash Provided by (Used in) Discontinued Operations [Abstract]
Operating activities				23,540
Investing activities				5,244
Change in cash and cash equivalents				$ 28,784
Pavonia \| Discontinued operations, held-for-sale \| Fixed maturity investments
ASSETS
Fixed maturities, trading, at fair value					$ 20,770

Investments - Contractual Maturities of Fixed Maturity and Short-term Investments Classified as Trading (Detail) $ in Thousands	Jun. 30, 2018 USD ($)
Amortized Cost
One year or less	$ 480,852
More than one year through two years	546,766
More than two years through five years	1,672,267
More than five years through ten years	1,476,591
More than ten years	1,325,143
Trading securities, amortized cost	6,805,879
Fair Value
One year or less	475,705
More than one year through two years	537,849
More than two years through five years	1,633,309
More than five years through ten years	1,435,235
More than ten years	1,310,713
Trading securities, debt	$ 6,688,325
% of Total Fair Value
One year or less	7.10%
More than one year through two years	8.00%
More than two years through five years	24.40%
More than five years through ten years	21.50%
More than ten years	19.60%
Trading securities, percentage of fair value	100.00%
Residential mortgage-backed
Amortized Cost
Securities without single maturity date	$ 304,249
Fair Value
Securities without single maturity date	$ 306,025
% of Total Fair Value
Securities without single maturity date	4.60%
Commercial mortgage-backed
Amortized Cost
Securities without single maturity date	$ 415,135
Fair Value
Securities without single maturity date	$ 403,001
% of Total Fair Value
Securities without single maturity date	6.00%
Asset-backed
Amortized Cost
Securities without single maturity date	$ 584,876
Fair Value
Securities without single maturity date	$ 586,488
% of Total Fair Value
Securities without single maturity date	8.80%

Investments - Amortized Cost and Fair Values of Fixed Maturity and Short-Term Investments Classified as Available-for-Sale (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 168,565	$ 208,097
Gross Unrealized Gains	2,896	3,693
Gross Unrealized Losses Non-OTTI	(2,140)	(1,505)
Fair Value	169,321	210,285
U.S. government and agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,429	4,210
Gross Unrealized Gains	0	0
Gross Unrealized Losses Non-OTTI	(9)	(23)
Fair Value	2,420	4,187
Non-U.S. government
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	75,679	84,776
Gross Unrealized Gains	1,423	1,249
Gross Unrealized Losses Non-OTTI	(915)	(588)
Fair Value	76,187	85,437
Corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	86,696	113,561
Gross Unrealized Gains	1,472	2,436
Gross Unrealized Losses Non-OTTI	(1,184)	(876)
Fair Value	86,984	115,121
Municipal
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,743	5,146
Gross Unrealized Gains	1	8
Gross Unrealized Losses Non-OTTI	(32)	(18)
Fair Value	3,712	5,136
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	18	31
Gross Unrealized Gains	0	0
Gross Unrealized Losses Non-OTTI	0	0
Fair Value	$ 18	31
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		373
Gross Unrealized Gains		0
Gross Unrealized Losses Non-OTTI		0
Fair Value		$ 373

Investments - Contractual Maturities of Fixed Maturity and Short-Term Investments Classified as Available-for-Sale (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Amortized Cost
One year or less	$ 20,321
More than one year through two years	20,422
More than two years through five years	40,382
More than five years through ten years	56,263
More than ten years	31,159
Amortized Cost	168,565	$ 208,097
Fair Value
One year or less	19,692
More than one year through two years	20,211
More than two years through five years	40,544
More than five years through ten years	56,890
More than ten years	31,966
Fair Value	$ 169,321	210,285
% of Total Fair Value
One year or less	11.60%
More than one year through two years	11.90%
More than two years through five years	24.00%
More than five years through ten years	33.60%
More than ten years	18.90%
Percentage of Total Fair Value	100.00%
Residential mortgage-backed
Amortized Cost
Securities without single maturity date	$ 18
Amortized Cost	18	31
Fair Value
Securities without single maturity date	18
Fair Value	$ 18	$ 31
% of Total Fair Value
Securities without single maturity date	0.00%

Investments - Gross Unrealized Losses (Detail) $ in Thousands	Jun. 30, 2018 USD ($) Security	Dec. 31, 2017 USD ($) Security
Fair Value
12 Months or Greater	$ 14,196	$ 22,991
Less Than 12 Months	45,961	50,612
Total	60,157	73,603
Gross Unrealized Losses
12 Months or Greater	(1,227)	(1,201)
Less Than 12 Months	(913)	(304)
Total	$ (2,140)	$ (1,505)
Number of securities classified as available-for-sale in an unrealized loss position \| Security	96	96
Number of securities classified as available-for-sale in an unrealized loss position for twelve months or longer \| Security	30	37
U.S. government and agency
Fair Value
12 Months or Greater	$ 2,293	$ 2,344
Less Than 12 Months	127	1,842
Total	2,420	4,186
Gross Unrealized Losses
12 Months or Greater	(8)	(16)
Less Than 12 Months	(1)	(7)
Total	(9)	(23)
Non-U.S. government
Fair Value
12 Months or Greater	4,270	11,101
Less Than 12 Months	18,007	20,965
Total	22,277	32,066
Gross Unrealized Losses
12 Months or Greater	(390)	(373)
Less Than 12 Months	(525)	(215)
Total	(915)	(588)
Corporate
Fair Value
12 Months or Greater	7,266	9,177
Less Than 12 Months	24,914	24,200
Total	32,180	33,377
Gross Unrealized Losses
12 Months or Greater	(822)	(807)
Less Than 12 Months	(362)	(69)
Total	(1,184)	(876)
Municipal
Fair Value
12 Months or Greater	367	369
Less Than 12 Months	2,913	3,605
Total	3,280	3,974
Gross Unrealized Losses
12 Months or Greater	(7)	(5)
Less Than 12 Months	(25)	(13)
Total	$ (32)	$ (18)

Investments - Other Than Temporary Impairment (Details) - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
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 - Other Investments, at Fair Value (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	May 14, 2018	Dec. 31, 2017
Other Investments [Line Items]
Valuation lag period	3 months
Other investments, at fair value	$ 1,768,333			$ 913,392
Additional subscriptions	462,336	$ 67,516
Unfunded commitments	200,000
CLO Equity Fund Two
Other Investments [Line Items]
Other investments, at fair value	40,900
Private equities and private equity funds
Other Investments [Line Items]
Other investments, at fair value	252,965			289,556
Unfunded commitments	$ 200,000
Fixed income funds
Other Investments [Line Items]
Notice period	45 days
Other investments, at fair value	$ 342,166			229,999
Hedge funds
Other Investments [Line Items]
Other investments, at fair value	670,963			63,773
Equity funds
Other Investments [Line Items]
Other investments, at fair value	387,490			249,475
CLO equities
Other Investments [Line Items]
Other investments, at fair value	53,840			56,765
CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	40,864			12,840
Private credit funds
Other Investments [Line Items]
Other investments, at fair value	14,319			10,156
Call options on equity
Other Investments [Line Items]
Other investments, at fair value	4,998			0
Other
Other Investments [Line Items]
Other investments, at fair value	$ 728			$ 828
Hedge Funds, Fixed Income
Other Investments [Line Items]
Imposed lock-up period (up to) (years)	3 years
Number of days to give notice for quarterly hedge fund redemptions	90 days
Gates or side-pocket investments	$ 400
Hedge Funds, Equity
Other Investments [Line Items]
Number of days to give notice for semi-annual redemption	60 days
KaylaRe
Other Investments [Line Items]
Other investments acquired			$ 626,476
Affiliated Entity \| KaylaRe
Other Investments [Line Items]
Additional subscriptions	$ 231,600

Investments - Other Investments, at Cost (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) contract
Other Investments [Line Items]
Amount of net investment income included in earnings attributable to investments in life settlements	$ 66,469	$ 49,417	$ 132,788	$ 98,156
Number of Contracts
0 – 1 year \| contract					0
1 – 2 years \| contract					11
2 – 3 years \| contract					10
3 – 4 years \| contract					20
4 – 5 years \| contract					13
Thereafter \| contract					162
Total \| contract					216
Carrying Value
0 – 1 year					$ 0
1 – 2 years					17,655
2 – 3 years					7,524
3 – 4 years					16,119
4 – 5 years					13,960
Thereafter					70,363
Total					125,621
Face Value (Death Benefits)
0 – 1 year					0
1 – 2 years					29,471
2 – 3 years					19,906
3 – 4 years					32,411
4 – 5 years					32,730
Thereafter					390,843
Total					$ 505,361
Life Settlements
Other Investments [Line Items]
Amount of net investment income included in earnings attributable to investments in life settlements			6,500	9,300
Impairment charges recognized in the period			$ 6,600	$ 6,300

Investments - Net Investment Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net Investment Income [Line Items]
Gross investment income	$ 69,015	$ 52,667	$ 138,203	$ 103,809
Investment expenses	(2,546)	(3,250)	(5,415)	(5,653)
Net investment income	66,469	49,417	132,788	98,156
Fixed maturity investments
Net Investment Income [Line Items]
Net investment income	48,147	33,741	92,035	64,071
Short-term investments and cash and cash equivalents
Net Investment Income [Line Items]
Net investment income	3,096	2,801	5,178	5,441
Funds held
Net Investment Income [Line Items]
Net investment income	2,754	311	5,883	350
Funds held - directly managed
Net Investment Income [Line Items]
Gross investment income	9,875	8,879	18,772	16,429
Investment expenses	(287)	(276)	(558)	(824)
Net investment income	9,588	8,603	18,214	15,605
Fixed Maturities and Cash and Cash Equivalents
Net Investment Income [Line Items]
Net investment income	63,585	45,456	121,310	85,467
Equity securities
Net Investment Income [Line Items]
Net investment income	1,352	1,137	2,842	1,863
Other investments
Net Investment Income [Line Items]
Net investment income	2,962	3,387	6,276	6,896
Life settlements and other
Net Investment Income [Line Items]
Net investment income	1,116	2,687	7,775	9,583
Investment income from equities and other investments
Net Investment Income [Line Items]
Net investment income	$ 5,430	$ 7,211	$ 16,893	$ 18,342

Investments - Net Realized and Unrealized Gains (Losses) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net realized gains (losses) on sale:
Total net realized gains on sale	$ (2,628)	$ 114	$ (8,606)	$ (4,068)
Net unrealized gains (losses):
Total net unrealized gains	(51,790)	51,763	(188,842)	114,464
Net realized and unrealized gains	(54,418)	51,877	(197,448)	110,396
Sales of available-for-sale securities	3,000	12,300	10,500	21,600
Fixed maturity securities
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, available-for-sale	20	177	27	337
Gross realized losses on fixed maturity securities, available-for-sale	(41)	(75)	(78)	(86)
Net realized gains (losses) on fixed maturity securities	(3,566)	65	(10,513)	(987)
Net unrealized gains (losses):
Net unrealized gains (losses) on trading securities	(45,967)	11,226	(146,268)	34,542
Equity securities
Net realized gains (losses) on sale:
Equity Securities, FV-NI, Realized Gain (Loss)	2,000	236	2,903	810
Net unrealized gains (losses):
Equity Securities, FV-NI, Unrealized Gain (Loss)	487	1,871	4,322	10,557
Other Investments
Net unrealized gains (losses):
Change in fair value of other investments	7,791	19,696	(1,871)	43,205
Change in fair value of embedded derivative	(13,044)	17,912	(40,925)	24,840
Funds held - directly managed
Net realized gains (losses) on sale:
Net realized gains (losses) on fixed maturity securities	(1,041)	(289)	(945)	(4,142)
Net realized gains (losses) on fixed maturity securities	(1,041)	(289)	(945)	(4,142)
Net unrealized gains (losses):
Change in fair value of embedded derivative	(13,044)	17,912	(40,925)	24,840
Change in value of fair value option on funds held - directly managed	(1,057)	1,058	(4,100)	1,320
Net realized and unrealized gains	$ (15,142)	$ 18,681	$ (45,970)	$ 22,018

Investments - Restricted Assets (Detail)	6 Months Ended
Investments - Restricted Assets (Detail)	Jun. 30, 2018 USD ($) Segment	Feb. 08, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)
Line of Credit Facility [Line Items]
Restricted cash and cash equivalents	$ 363,884,000		$ 257,686,000	$ 423,683,000
Collateral in trust for third party agreements	3,399,091,000		3,118,892,000
Assets on deposit with regulatory authorities	585,922,000		599,829,000
Funds at Lloyd's	417,333,000		234,833,000
Restricted assets, total	$ 4,535,623,000		4,105,021,000
Number of syndicates \| Segment	3
Cash and investments	$ 417,300,000
FAL Facility \| Line of Credit \| Letters of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	295,000,000	$ 325,000,000
Higher borrowing capacity option		$ 400,000,000
Asset Pledged as Collateral
Line of Credit Facility [Line Items]
Collateral for secured letter of credit facilities	$ 133,277,000		$ 151,467,000

Funds Held - Directly Managed - Additional Information (Details) - Allianz - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Schedule of Funds Held, Directly Managed [Line Items]
Funds held - directly managed, at cost, carrying value	$ 1,087.6	$ 994.8
Funds held - directly managed, fair value of embedded derivative	(36.3)	4.7
Funds held - directly managed	$ 1,051.3	$ 999.5

Funds Held - Directly Managed - Carrying Values of Assets and Liabilities Underlying Funds Held - Directly Managed (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Funds Held, Directly Managed [Line Items]
Fair Value	$ 6,688,325
Funds held - directly managed	1,229,896	$ 1,179,940
Funds held - directly managed, other assets
Schedule of Funds Held, Directly Managed [Line Items]
Fair Value	1,220,744	1,165,386
Funds held - directly managed, other assets	9,152	14,554
U.S. government and agency \| Funds held - directly managed, other assets
Schedule of Funds Held, Directly Managed [Line Items]
Fair Value	87,017	69,850
Non-U.S. government \| Funds held - directly managed, other assets
Schedule of Funds Held, Directly Managed [Line Items]
Fair Value	22,625	2,926
Corporate \| Funds held - directly managed, other assets
Schedule of Funds Held, Directly Managed [Line Items]
Fair Value	672,437	695,490
Municipal \| Funds held - directly managed, other assets
Schedule of Funds Held, Directly Managed [Line Items]
Fair Value	58,933	58,930
Residential mortgage-backed \| Funds held - directly managed, other assets
Schedule of Funds Held, Directly Managed [Line Items]
Fair Value	60,260	29,439
Commercial mortgage-backed \| Funds held - directly managed, other assets
Schedule of Funds Held, Directly Managed [Line Items]
Fair Value	221,133	211,186
Asset-backed \| Funds held - directly managed, other assets
Schedule of Funds Held, Directly Managed [Line Items]
Fair Value	$ 98,339	$ 97,565

Funds Held - Directly Managed - Contractual Maturities of Fixed Maturity Investments Underlying Funds Held - Directly Managed (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Amortized Cost
One year or less	$ 480,852
More than one year through two years	546,766
More than two years through five years	1,672,267
More than five years through ten years	1,476,591
More than ten years	1,325,143
Trading securities, amortized cost	6,805,879
Fair Value
One year or less	475,705
More than one year through two years	537,849
More than two years through five years	1,633,309
More than five years through ten years	1,435,235
More than ten years	1,310,713
Trading securities, debt	$ 6,688,325
% of Total Fair Value
One year or less	7.10%
More than one year through two years	8.00%
More than two years through five years	24.40%
More than five years through ten years	21.50%
More than ten years	19.60%
Trading securities, percentage of fair value	100.00%
Residential mortgage-backed
Amortized Cost
Securities without single maturity date	$ 304,249
Fair Value
Securities without single maturity date	$ 306,025
% of Total Fair Value
Securities without single maturity date	4.60%
Commercial mortgage-backed
Amortized Cost
Securities without single maturity date	$ 415,135
Fair Value
Securities without single maturity date	$ 403,001
% of Total Fair Value
Securities without single maturity date	6.00%
Asset-backed
Amortized Cost
Securities without single maturity date	$ 584,876
Fair Value
Securities without single maturity date	$ 586,488
% of Total Fair Value
Securities without single maturity date	8.80%
Funds held - directly managed
Amortized Cost
One year or less	$ 23,555
More than one year through two years	74,264
More than two years through five years	245,586
More than five years through ten years	268,392
More than ten years	256,716
Trading securities, amortized cost	1,260,182
Fair Value
One year or less	23,456
More than one year through two years	73,553
More than two years through five years	239,757
More than five years through ten years	256,849
More than ten years	247,397
Trading securities, debt	$ 1,220,744	$ 1,165,386
% of Total Fair Value
One year or less	1.90%
More than one year through two years	6.00%
More than two years through five years	19.60%
More than five years through ten years	21.10%
More than ten years	20.30%
Trading securities, percentage of fair value	100.00%
Funds held - directly managed \| Residential mortgage-backed
Amortized Cost
Securities without single maturity date	$ 61,362
Fair Value
Securities without single maturity date	60,260
Trading securities, debt	$ 60,260	29,439
% of Total Fair Value
Securities without single maturity date	4.90%
Funds held - directly managed \| Commercial mortgage-backed
Amortized Cost
Securities without single maturity date	$ 231,947
Fair Value
Securities without single maturity date	221,133
Trading securities, debt	$ 221,133	211,186
% of Total Fair Value
Securities without single maturity date	18.10%
Funds held - directly managed \| Asset-backed
Amortized Cost
Securities without single maturity date	$ 98,360
Fair Value
Securities without single maturity date	98,339
Trading securities, debt	$ 98,339	$ 97,565
% of Total Fair Value
Securities without single maturity date	8.10%

Funds Held - Directly Managed - Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net Investment Income [Line Items]
Gross investment income	$ 69,015	$ 52,667	$ 138,203	$ 103,809
Investment expenses	(2,546)	(3,250)	(5,415)	(5,653)
Net investment income	66,469	49,417	132,788	98,156
Funds held - directly managed
Net Investment Income [Line Items]
Gross investment income	9,875	8,879	18,772	16,429
Investment expenses	(287)	(276)	(558)	(824)
Net investment income	9,588	8,603	18,214	15,605
Funds held - directly managed \| Fixed maturity investments
Net Investment Income [Line Items]
Gross investment income	9,817	8,817	18,635	16,302
Funds held - directly managed \| Short-term investments and cash and cash equivalents
Net Investment Income [Line Items]
Gross investment income	$ 58	$ 62	$ 137	$ 127

Funds Held - Directly Managed - Net Realized and Unrealized Investment (Losses) Gains (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Gain (Loss) on Securities [Line Items]
Net realized and unrealized gains	$ (54,418)	$ 51,877	$ (197,448)	$ 110,396
Funds held - directly managed
Gain (Loss) on Securities [Line Items]
Net realized gains (losses) on fixed maturity securities	(1,041)	(289)	(945)	(4,142)
Change in fair value of embedded derivative	(13,044)	17,912	(40,925)	24,840
Change in value of fair value option on funds held - directly managed	(1,057)	1,058	(4,100)	1,320
Net realized and unrealized gains	$ (15,142)	$ 18,681	$ (45,970)	$ 22,018

Fair Value Measurements - Investments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reinsurance balances recoverable
Beginning fair value	$ 184,224	$ 179,740	$ 176,723	$ 178,317
Purchases	31,884	18,029	45,949	28,298
Sales	(55,667)	(14,318)	(68,233)	(33,217)
Total realized and unrealized gains (losses)	(2,925)	92	(3,176)	(6,524)
Transfer into Level 3 from Level 2	2,079	39,168	22,235	72,197
Transfer out of Level 3 into Level 2	(13,668)	(47,245)	(27,571)	(63,605)
Ending fair value	145,927	175,466	145,927	175,466
Corporate
Reinsurance balances recoverable
Beginning fair value	86,027	56,179	67,178	74,534
Purchases	971	6,679	11,803	15,568
Sales	(53,873)	(6,461)	(60,910)	(25,117)
Total realized and unrealized gains (losses)	(258)	191	(63)	650
Transfer into Level 3 from Level 2	0	3,378	15,259	4,945
Transfer out of Level 3 into Level 2	(5,044)	(5,610)	(5,444)	(16,224)
Ending fair value	27,823	54,356	27,823	54,356
Residential mortgage-backed
Reinsurance balances recoverable
Beginning fair value	1,907	0	3,080	0
Purchases	0	711	0	711
Sales	(36)	(5)	(1,184)	(5)
Total realized and unrealized gains (losses)	(8)	(13)	(33)	(13)
Transfer into Level 3 from Level 2	0	0	0	0
Transfer out of Level 3 into Level 2	(1,863)	0	(1,863)	0
Ending fair value	0	693	0	693
Commercial mortgage-backed
Reinsurance balances recoverable
Beginning fair value	17,634	24,852	21,494	12,213
Purchases	0	10,347	1,803	10,347
Sales	(1,150)	(734)	(1,727)	(734)
Total realized and unrealized gains (losses)	(31)	436	52	331
Transfer into Level 3 from Level 2	0	4,015	4,897	17,916
Transfer out of Level 3 into Level 2	(1,127)	(16,051)	(11,193)	(17,208)
Ending fair value	15,326	22,865	15,326	22,865
Asset-backed
Reinsurance balances recoverable
Beginning fair value	21,997	29,082	27,892	14,692
Purchases	28,291	0	29,591	1,380
Sales	(8)	(7,118)	(3,812)	(7,361)
Total realized and unrealized gains (losses)	(117)	(72)	(71)	209
Transfer into Level 3 from Level 2	2,079	31,775	2,079	49,336
Transfer out of Level 3 into Level 2	(5,634)	(13,234)	(9,071)	(17,823)
Ending fair value	46,608	40,433	46,608	40,433
Equities - U.S.
Reinsurance balances recoverable
Beginning fair value	0	0	0	0
Purchases	2,000	0	2,000	0
Sales	0	0	0	0
Total realized and unrealized gains (losses)	16	0	16	0
Transfer into Level 3 from Level 2	0	0	0	0
Transfer out of Level 3 into Level 2	0	0	0	0
Ending fair value	2,016	0	2,016	0
Other Investments
Reinsurance balances recoverable
Beginning fair value	56,659	69,627	57,079	76,878
Purchases	622	292	752	292
Sales	(600)	0	(600)	0
Total realized and unrealized gains (losses)	(2,527)	(450)	(3,077)	(7,701)
Transfer into Level 3 from Level 2	0	0	0	0
Transfer out of Level 3 into Level 2	0	(12,350)	0	(12,350)
Ending fair value	$ 54,154	$ 57,119	$ 54,154	$ 57,119

Fair Value Measurements - Insurance Contracts (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reinsurance balances recoverable
Beginning fair value	$ 184,224	$ 179,740	$ 176,723	$ 178,317
Assumed business	31,884	18,029	45,949	28,298
Changes in fair value:
Ending fair value	145,927	175,466	145,927	175,466
Losses and LAE liabilities
Liability for losses and LAE
Beginning fair value	3,519,453	1,924,829	1,794,669	0
Assumed business	0	0	1,890,061	1,966,843
Changes in nominal amounts:
Net incurred losses and LAE	(48,899)	(26,407)	(55,196)	(32,645)
Paid losses	(145,676)	(39,686)	(304,048)	(100,053)
Changes in fair value:
Discounted cash flows	29,141	(3,354)	(20,863)	17,013
Risk margin	(11,595)	(4,563)	(18,746)	(9,052)
Effect of exchange rate movements	(121,058)	41,478	(64,511)	50,191
Ending fair value	3,221,366	1,892,297	3,221,366	1,892,297
Reinsurance balances recoverable
Reinsurance balances recoverable
Beginning fair value	888,736	551,253	542,224	0
Assumed business	0	0	372,780	565,824
Changes in nominal amounts:
Net incurred losses and LAE	3,860	(2,095)	2,384	(2,095)
Paid losses	(35,389)	(4,488)	(53,535)	(21,494)
Changes in fair value:
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings, Discounted Cash Flows	2,067	5,947	(13,882)	8,413
Risk margin	(1,754)	(632)	(2,719)	(1,702)
Effect of exchange rate movements	(20,147)	4,774	(9,879)	5,813
Ending fair value	$ 837,373	$ 554,759	$ 837,373	$ 554,759

Fair Value Measurements - Observable and Unobservable Inputs (Details) - Internal Model - Recurring	6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
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 11 months 12 days		11 years 4 months 27 days
Reinsurance balances recoverable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk cost of capital		5.00%	5.00%
Duration	8 years 11 months 8 days		11 years 7 months 29 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	Jun. 30, 2018	Dec. 31, 2017	Mar. 10, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt, amortized cost	$ 439,610	$ 646,689
Fair Value \| Life Settlement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Life settlements		131,900
Carrying Value \| Life Settlement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Life settlements		125,600
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	$ 347,715	347,516
Debt, fair value		$ 348,400

Derivative and Hedging Instruments - Foreign Currency Hedging of Net Investments (Detail) $ in Thousands, € in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 EUR (€)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 EUR (€)
Not designated as hedging instrument \| Foreign exchange forward
Derivative [Line Items]
Gross Notional Amount	$ 412,379		$ 412,379			$ 283,586
Assets	11,746		11,746			308
Liabilities	77		77			5,769
Gains (Losses) on non-qualifying hedges included in net earnings	19,422	$ (965)	15,335	$ (1,303)
Not designated as hedging instrument \| Foreign exchange forward \| AUD
Derivative [Line Items]
Gross Notional Amount	46,582		46,582			57,028
Assets	833		833			0
Liabilities	0		0			1,002
Gains (Losses) on non-qualifying hedges included in net earnings	1,514	0	2,496	0
Not designated as hedging instrument \| Foreign exchange forward \| GBP
Derivative [Line Items]
Gross Notional Amount	218,228		218,228			207,323
Assets	5,700		5,700			262
Liabilities	0		0			4,312
Gains (Losses) on non-qualifying hedges included in net earnings	11,077	(611)	4,235	(740)
Not designated as hedging instrument \| Foreign exchange forward \| EUR
Derivative [Line Items]
Gross Notional Amount	32,696		32,696			19,235
Assets	958		958			46
Liabilities	0		0			455
Gains (Losses) on non-qualifying hedges included in net earnings	1,624	(354)	1,357	(563)
Not designated as hedging instrument \| Foreign exchange forward \| CAD
Derivative [Line Items]
Gross Notional Amount	114,873		114,873			0
Assets	4,255		4,255			0
Liabilities	77		77			0
Gains (Losses) on non-qualifying hedges included in net earnings	5,207	0	7,247	0
Designated as Hedging Instrument \| Foreign exchange forward
Derivative [Line Items]
Gross Notional Amount	27,358		27,358			59,951
Assets	571		571			11
Liabilities	0		0			1,477
Net gains (losses) on qualifying derivative hedges	1,078	(1,675)	1,608	(678)
Designated as Hedging Instrument \| Foreign exchange forward \| AUD
Derivative [Line Items]
Gross Notional Amount	27,358		27,358			32,810
Assets	571		571			0
Liabilities	0		0			965
Net gains (losses) on qualifying derivative hedges	1,078	(1,007)	1,608	(562)
Designated as Hedging Instrument \| Foreign exchange forward \| CAD
Derivative [Line Items]
Gross Notional Amount	0		0			27,141
Assets	0		0			11
Liabilities	0		0			512
Net gains (losses) on qualifying derivative hedges	0	(668)	0	(116)
Net Investment Hedging
Derivative [Line Items]
Gross Notional Amount	70,100		70,100		€ 60.0	$ 60,100	€ 50.0
Net gains (losses) on qualifying non-derivative hedges	$ 3,684	$ (5,370)	$ 2,448	$ (6,495)

Derivative and Hedging Instruments - Investments in Call Options on Equities (Details) - Call options on equity $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018 USD ($) derivative_instrument	Jun. 30, 2018 USD ($) derivative_instrument	Dec. 31, 2017 derivative_instrument
Derivative [Line Items]
Number of equity derivative instruments \| derivative_instrument	0	0	0
Not designated as hedging instrument
Derivative [Line Items]
Cost	$ 10.0	$ 10.0
Unrealized gain (loss) on equity securities	$ (2.5)	$ (5.0)

Reinsurance Balances Recoverable - Total Reinsurance Balances (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Effects of Reinsurance [Line Items]
Outstanding losses	$ 1,184,414		$ 1,151,422
IBNR	866,067		864,250
Fair value adjustments	(14,332)		(13,640)
Fair value adjustments - fair value option	(169,180)		(131,983)
Total reinsurance reserves recoverable	1,866,969		1,870,049	$ 1,923,962
Paid losses recoverable	127,842		150,981
Net	1,994,811		2,021,030
Reinsurance balances recoverable	1,157,438		1,478,806
Reinsurance balances recoverable, at fair value	837,373		542,224
Non-life Run-off
Effects of Reinsurance [Line Items]
Outstanding losses	994,389		932,284
IBNR	650,106		590,154
Fair value adjustments	(13,176)		(12,970)
Fair value adjustments - fair value option	(169,180)		(131,983)
Total reinsurance reserves recoverable	1,462,139	$ 1,703,481	1,377,485	1,500,557	$ 1,504,371	$ 1,000,953
Paid losses recoverable	112,153		128,253
Net	1,574,292		1,505,738
Reinsurance balances recoverable	736,919		963,514
Reinsurance balances recoverable, at fair value	837,373		542,224
Atrium
Effects of Reinsurance [Line Items]
Outstanding losses	13,442		7,472
IBNR	24,036		31,476
Fair value adjustments	775		1,583
Fair value adjustments - fair value option	0		0
Total reinsurance reserves recoverable	38,253	40,025	40,531	29,749	30,625	30,009
Paid losses recoverable	(648)		(451)
Net	37,605		40,080
Reinsurance balances recoverable	37,605		40,080
Reinsurance balances recoverable, at fair value	0		0
StarStone
Effects of Reinsurance [Line Items]
Outstanding losses	176,583		211,650
IBNR	191,925		242,620
Fair value adjustments	(1,931)		(2,253)
Fair value adjustments - fair value option	0		0
Total reinsurance reserves recoverable	366,577	$ 473,527	452,017	$ 393,656	$ 360,495	$ 357,231
Paid losses recoverable	16,337		23,179
Net	382,914		475,196
Reinsurance balances recoverable	382,914		475,196
Reinsurance balances recoverable, at fair value	$ 0		0
Other
Effects of Reinsurance [Line Items]
Outstanding losses			16
IBNR			0
Fair value adjustments			0
Fair value adjustments - fair value option			0
Total reinsurance reserves recoverable			16
Paid losses recoverable			0
Net			16
Reinsurance balances recoverable			16
Reinsurance balances recoverable, at fair value			$ 0

Reinsurance Balances Recoverable - Additional Information (Detail) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018 USD ($) reinsurer	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) reinsurer
Effects of Reinsurance [Line Items]
Increase (decrease) in reinsurance recoverable	$ 339,827	$ 570,731
Reinsurance balances recoverable	$ 1,994,811		$ 2,021,030
Reinsurer Concentration Risk \| Top Ten Reinsurers, Rated A Minus Or Higher
Effects of Reinsurance [Line Items]
Number of external reinsurers \| reinsurer	7		6
Reinsurer Concentration Risk \| Top Ten Reinsurers, Four Non-Rated Reinsurers
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 319,400		$ 687,600
Number of external reinsurers \| reinsurer	3		4
Equity Method Investee \| Reinsurer Concentration Risk \| Lloyd's Syndicates
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 308,100		$ 193,800
Equity Method Investee \| Reinsurer Concentration Risk \| Hannover Ruck SE
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	328,200		320,000
Non-Life Run-Off and StarStone Segment
Effects of Reinsurance [Line Items]
Increase (decrease) in reinsurance recoverable	(26,200)
Reinsurance balances recoverable \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 1,994,811		$ 2,021,030
Concentration risk percentage	100.00%		100.00%
Reinsurance balances recoverable \| Reinsurer Concentration Risk \| Two Reinsurer Accounting for More than Ten Percentage of Reinsurance Balances Receivable
Effects of Reinsurance [Line Items]
Concentration risk percentage	10.00%

Reinsurance Balances Recoverable Reinsurance Balances Recoverable - Top Ten Reinsurers (Details) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018 USD ($) reinsurer	Dec. 31, 2017 USD ($) reinsurer
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 1,994,811	$ 2,021,030
Top Ten Reinsurers, Rated A Minus Or Higher \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Number of external reinsurers \| reinsurer	7	6
Top Ten Reinsurers, Four Non-Rated Reinsurers \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Number of external reinsurers \| reinsurer	3	4
Reinsurance balances recoverable	$ 319,400	$ 687,600
Reinsurance balances recoverable \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 1,994,811	$ 2,021,030
Concentration risk percentage	100.00%	100.00%
Reinsurance balances recoverable \| Top ten reinsurers \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 1,453,615	$ 1,516,736
Concentration risk percentage	72.90%	75.00%
Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 523,587	$ 483,689
Concentration risk percentage	26.20%	24.00%
Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 17,609	$ 20,605
Concentration risk percentage	0.90%	1.00%
Non-life Run-off
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 1,574,292	$ 1,505,738
Non-life Run-off \| Reinsurance balances recoverable \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	1,574,292	1,505,738
Non-life Run-off \| Reinsurance balances recoverable \| Top ten reinsurers \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	1,212,447	1,166,057
Non-life Run-off \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	347,782	322,722
Non-life Run-off \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	14,063	16,959
Atrium
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	37,605	40,080
Atrium \| Reinsurance balances recoverable \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	37,605	40,080
Atrium \| Reinsurance balances recoverable \| Top ten reinsurers \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	20,095	22,422
Atrium \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	16,796	16,631
Atrium \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	714	1,027
StarStone
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	382,914	475,196
StarStone \| Reinsurance balances recoverable \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	382,914	475,196
StarStone \| Reinsurance balances recoverable \| Top ten reinsurers \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	221,073	328,257
StarStone \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	159,009	144,336
StarStone \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable	$ 2,832	2,603
Other
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable		16
Other \| Reinsurance balances recoverable \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable		16
Other \| Reinsurance balances recoverable \| Top ten reinsurers \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable		0
Other \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable		0
Other \| Reinsurance balances recoverable \| Other reinsurers $1 million \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable		$ 16

Reinsurance Balances Recoverable - Summary of Provisions for Uncollectible Reinsurance Balances Recoverable by Rating of Reinsurer (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Effects of Reinsurance [Line Items]
Gross	$ 2,155,707	$ 2,186,243
Provisions for Bad Debt	160,896	165,213
Net	$ 1,994,811	$ 2,021,030
Provisions as a % of Gross	7.50%	7.60%
Reinsurers rated A- or above
Effects of Reinsurance [Line Items]
Gross	$ 1,623,739	$ 1,252,887
Provisions for Bad Debt	59,230	51,115
Net	$ 1,564,509	$ 1,201,772
Provisions as a % of Gross	3.60%	4.10%
Secured \| Reinsurers rated below A-
Effects of Reinsurance [Line Items]
Gross	$ 398,335	$ 771,097
Provisions for Bad Debt	0	0
Net	$ 398,335	$ 771,097
Provisions as a % of Gross	0.00%	0.00%
Unsecured \| Reinsurers rated below A-
Effects of Reinsurance [Line Items]
Gross	$ 133,633	$ 162,259
Provisions for Bad Debt	101,666	114,098
Net	$ 31,967	$ 48,161
Provisions as a % of Gross	76.10%	70.30%

Losses and Loss Adjustment Expenses - Total Losses and Loss Adjustment Expense Liabilities (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	$ 4,892,287		$ 4,892,287			$ 3,855,043
IBNR	3,895,277		3,895,277			3,653,656
Fair value adjustments	(115,048)		(115,048)			(117,006)
Fair value adjustments - fair value option	(440,024)		(440,024)			(314,748)
ULAE	375,895		375,895			321,143
Total	8,608,387	$ 7,641,384	8,608,387	$ 7,641,384	$ 8,986,070	7,398,088	$ 7,760,587	$ 5,987,867
Losses and loss adjustment expenses	5,387,021		5,387,021			5,603,419
Losses and loss adjustment expenses, at fair value	3,221,366		3,221,366			1,794,669
Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Increase (reduction) in provisions for unallocated LAE	(9,311)	(10,989)	(24,263)	(25,354)
Outstanding losses	4,148,834		4,148,834			3,185,703
IBNR	3,084,112		3,084,112			2,903,927
Fair value adjustments	(119,937)		(119,937)			(125,998)
Fair value adjustments - fair value option	(440,024)		(440,024)			(314,748)
ULAE	352,765		352,765			300,588
Total	7,025,750	6,317,279	7,025,750	6,317,279	7,517,511	5,949,472	6,478,150	4,716,363
Atrium
Liability for Claims and Claims Adjustment Expense [Line Items]
Increase (reduction) in provisions for unallocated LAE	2	49	2	(75)
Outstanding losses	84,214		84,214			78,363
IBNR	142,320		142,320			150,508
Fair value adjustments	5,364		5,364			9,547
Fair value adjustments - fair value option	0		0			0
ULAE	2,334		2,334			2,455
Total	234,232	208,646	234,232	208,646	240,795	240,873	212,123	212,122
StarStone
Liability for Claims and Claims Adjustment Expense [Line Items]
Increase (reduction) in provisions for unallocated LAE	(1,189)	(1,205)	(3,290)	(3,131)
Outstanding losses	659,239		659,239			590,977
IBNR	668,845		668,845			599,221
Fair value adjustments	(475)		(475)			(555)
Fair value adjustments - fair value option	0		0			0
ULAE	20,796		20,796			18,100
Total	$ 1,348,405	$ 1,115,459	$ 1,348,405	$ 1,115,459	$ 1,227,764	$ 1,207,743	$ 1,070,314	$ 1,059,382

Losses and Loss Adjustment Expenses - Reconciliation of Beginning and Ending Reserves for Losses and Loss Adjustment Expenses (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as at beginning of period	$ 8,986,070	$ 7,398,088	$ 7,760,587	$ 5,987,867	$ 7,398,088	$ 5,987,867	$ 5,987,867
Less: reinsurance reserves recoverable		1,870,049			1,870,049
Less: deferred charges on retroactive reinsurance	75,111	80,192	93,605	94,551	80,192	94,551	94,551
Net balance as at beginning of period	6,693,926	5,447,863	5,771,491	4,505,123	5,447,863	4,505,123	4,505,123
Net incurred losses and LAE:
Current period	153,860		81,400		249,014	166,945
Prior periods	(61,041)		(71,780)		(136,661)	(79,433)
Total net incurred losses and LAE	92,819		9,620		112,353	87,512
Net paid losses:
Current period	(30,474)		(16,173)		(38,577)	(24,892)
Prior periods	(290,491)		(205,222)		(641,137)	(454,944)
Net losses paid	(320,965)		(221,395)		(679,714)	(479,836)
Effect of exchange rate movement	(139,561)		69,231		(81,834)	83,736
Liability for Unpaid Claims and Claims Adjustment Expense, Business Acquisitions		343,806		0			343,806	$ 0
Assumed business	0		0		1,527,551	1,432,412
Net balance as at June 30	6,670,025	6,693,926	5,628,947	5,771,491	6,670,025	5,628,947	5,447,863	4,505,123
Plus: reinsurance reserves recoverable	1,866,969		1,923,962		1,866,969	1,923,962	1,870,049
Plus: deferred charges on retroactive reinsurance	71,393	75,111	88,475	93,605	71,393	88,475	80,192	94,551
Balance as at June 30	8,608,387	8,986,070	7,641,384	7,760,587	8,608,387	7,641,384	7,398,088	5,987,867
Non-Life Run-off Segment, Atrium Segment, and Starstone Segment
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less: reinsurance reserves recoverable	2,217,033	1,870,033	1,895,491	1,388,193	1,870,033	1,388,193	1,388,193
Net paid losses:
Plus: reinsurance reserves recoverable	1,866,969	2,217,033	1,923,962	1,895,491	1,866,969	1,923,962	1,870,033	1,388,193
Non-life Run-off
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as at beginning of period	7,517,511	5,949,472	6,478,150	4,716,363	5,949,472	4,716,363	4,716,363
Less: reinsurance reserves recoverable	1,703,481	1,377,485	1,504,371	1,000,953	1,377,485	1,000,953	1,000,953
Less: deferred charges on retroactive reinsurance	75,111	80,192	93,605	94,551	80,192	94,551	94,551
Net balance as at beginning of period	5,738,919	4,491,795	4,880,174	3,620,859	4,491,795	3,620,859	3,620,859
Net incurred losses and LAE:
Current period	5,113		461		5,459	1,175
Prior periods	(75,247)		(64,863)		(148,571)	(68,334)
Total net incurred losses and LAE	(70,134)		(64,402)		(143,112)	(67,159)
Net paid losses:
Current period	(590)		(130)		(591)	(371)
Prior periods	(195,721)		(144,282)		(448,304)	(300,613)
Net losses paid	(196,311)		(144,412)		(448,895)	(300,984)
Effect of exchange rate movement	(131,081)		56,887		(75,678)	74,512
Liability for Unpaid Claims and Claims Adjustment Expense, Business Acquisitions		150,825		0			150,825	0
Assumed business	0		0		1,517,283	1,401,019
Net balance as at June 30	5,492,218	5,738,919	4,728,247	4,880,174	5,492,218	4,728,247	4,491,795	3,620,859
Plus: reinsurance reserves recoverable	1,462,139	1,703,481	1,500,557	1,504,371	1,462,139	1,500,557	1,377,485	1,000,953
Plus: deferred charges on retroactive reinsurance	71,393	75,111	88,475	93,605	71,393	88,475	80,192	94,551
Balance as at June 30	7,025,750	7,517,511	6,317,279	6,478,150	7,025,750	6,317,279	5,949,472	4,716,363
Atrium
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as at beginning of period	240,795	240,873	212,123	212,122	240,873	212,122	212,122
Less: reinsurance reserves recoverable	40,025	40,531	30,625	30,009	40,531	30,009	30,009
Net balance as at beginning of period	200,770	200,342	181,498	182,113	200,342	182,113	182,113
Net incurred losses and LAE:
Current period	19,175		14,858		36,481	29,279
Prior periods	(2,249)		(6,669)		(2,383)	(8,602)
Total net incurred losses and LAE	16,926		8,189		34,098	20,677
Net paid losses:
Current period	(10,465)		(5,398)		(17,619)	(9,660)
Prior periods	(8,882)		(7,423)		(19,258)	(16,834)
Net losses paid	(19,347)		(12,821)		(36,877)	(26,494)
Effect of exchange rate movement	(2,370)		2,031		(1,584)	2,601
Net balance as at June 30	195,979	200,770	178,897	181,498	195,979	178,897	200,342	182,113
Plus: reinsurance reserves recoverable	38,253	40,025	29,749	30,625	38,253	29,749	40,531	30,009
Balance as at June 30	234,232	240,795	208,646	212,123	234,232	208,646	240,873	212,122
StarStone
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as at beginning of period	1,227,764	1,207,743	1,070,314	1,059,382	1,207,743	1,059,382	1,059,382
Less: reinsurance reserves recoverable	473,527	452,017	360,495	357,231	452,017	357,231	357,231
Net balance as at beginning of period	754,237	755,726	709,819	702,151	755,726	702,151	702,151
Net incurred losses and LAE:
Current period	129,572		66,081		207,074	136,491
Prior periods	16,455		(248)		14,293	(2,497)
Total net incurred losses and LAE	146,027		65,833		221,367	133,994
Net paid losses:
Current period	(19,419)		(10,645)		(20,367)	(14,861)
Prior periods	(85,888)		(53,517)		(173,575)	(137,497)
Net losses paid	(105,307)		(64,162)		(193,942)	(152,358)
Effect of exchange rate movement	(6,110)		10,313		(4,572)	6,623
Liability for Unpaid Claims and Claims Adjustment Expense, Business Acquisitions	192,981		0		192,981	0
Assumed business	0		0		10,268	31,393
Net balance as at June 30	981,828	754,237	721,803	709,819	981,828	721,803	755,726	702,151
Plus: reinsurance reserves recoverable	366,577	473,527	393,656	360,495	366,577	393,656	452,017	357,231
Balance as at June 30	$ 1,348,405	$ 1,227,764	$ 1,115,459	$ 1,070,314	$ 1,348,405	$ 1,115,459	$ 1,207,743	$ 1,059,382

Losses and Loss Adjustment Expenses - Net (Reduction) Increase in Ultimate Losses and Loss Adjustment Expense Liabilities (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Prior Period
Net losses paid	$ 290,491	$ 205,222	$ 641,137	$ 454,944
Net incurred losses and LAE, prior period	(61,041)	(71,780)	(136,661)	(79,433)
Current Period
Net losses paid	30,474	16,173	38,577	24,892
Net incurred losses and LAE, current period	153,860	81,400	249,014	166,945
Net premiums written	253,219	149,548	476,366	311,607
Total
Net losses paid	320,965	221,395	679,714	479,836
Net change in case and LAE reserves	(101,965)	(120,385)	(226,036)	(212,284)
Net change in IBNR reserves	(143,042)	(72,503)	(307,733)	(163,106)
Amortization of deferred charges	3,718	5,130	8,799	6,076
Increase (reduction) in estimates of net ultimate losses	79,676	33,637	154,744	110,522
Reduction in provisions for bad debt	0	(735)	0	(735)
Increase (reduction) in provisions for unallocated LAE	(7,071)	(10,704)	(21,831)	(25,036)
Amortization of fair value adjustments	2,981	654	2,448	1,511
Changes in fair value - fair value option	17,233	(13,232)	(23,008)	1,250
Total net incurred losses and LAE	92,819	9,620	112,353	87,512
Non-life Run-off
Prior Period
Net losses paid	195,721	144,282	448,304	300,613
Net change in case and LAE reserves	(125,416)	(127,393)	(248,908)	(210,527)
Net change in IBNR reserves	(161,110)	(62,604)	(315,560)	(141,682)
Amortization of deferred charges	3,718	5,130	8,799
Increase (reduction) in estimates of net ultimate losses	(87,087)	(40,585)	(107,365)	(45,520)
Reduction in provisions for bad debt	0	(735)	0	(735)
Increase (reduction) in provisions for unallocated LAE	(9,311)	(10,989)	(24,263)	(25,354)
Amortization of fair value adjustments	3,918	678	6,065	2,025
Net change in case and IBNR reserves		(190,000)
Changes in fair value - fair value option	17,233	(13,232)	(23,008)	1,250
Net incurred losses and LAE, prior period	(75,247)	(64,863)	(148,571)	(68,334)
Current Period
Net losses paid	590	130	591	371
Net change in case and LAE reserves	1,052	(16)	1,058	(16)
Net change in IBNR reserves	3,471	293	3,810	724
Amortization of deferred charges	0	0	0	0
Increase (reduction) in estimates of net ultimate losses	5,113	407	5,459	1,079
Reduction in provisions for bad debt	0	0	0	0
Increase (reduction) in provisions for unallocated LAE	0	54	0	96
Amortization of fair value adjustments	0	0	0	0
Changes in fair value - fair value option	0	0	0	0
Net incurred losses and LAE, current period	5,113	461	5,459	1,175
Net premiums written	(1,661)	1,905	(1,561)	1,986
Total
Net losses paid	196,311	144,412	448,895	300,984
Net change in case and LAE reserves	(124,364)	(127,409)	(247,850)	(210,543)
Net change in IBNR reserves	(157,639)	(62,311)	(311,750)	(140,958)
Amortization of deferred charges	3,718	5,130	8,799	6,076
Increase (reduction) in estimates of net ultimate losses	(81,974)	(40,178)	(101,906)	(44,441)
Reduction in provisions for bad debt	0	(735)	0	(735)
Increase (reduction) in provisions for unallocated LAE	(9,311)	(10,935)	(24,263)	(25,258)
Amortization of fair value adjustments	3,918	678	6,065	2,025
Changes in fair value - fair value option	17,233	(13,232)	(23,008)	1,250
Total net incurred losses and LAE	(70,134)	(64,402)	(143,112)	(67,159)
Atrium
Prior Period
Net losses paid	8,882	7,423	19,258	16,834
Net change in case and LAE reserves	(3,169)	(2,007)	(5,553)	(5,123)
Net change in IBNR reserves	(7,128)	(12,221)	(12,715)	(20,358)
Increase (reduction) in estimates of net ultimate losses	(1,415)	(6,805)	990	(8,647)
Increase (reduction) in provisions for unallocated LAE	2	49	2	(75)
Amortization of fair value adjustments	(836)	87	(3,375)	120
Net incurred losses and LAE, prior period	(2,249)	(6,669)	(2,383)	(8,602)
Current Period
Net losses paid	10,465	5,398	17,619	9,660
Net change in case and LAE reserves	(273)	886	6,001	4,596
Net change in IBNR reserves	8,983	8,679	12,861	15,012
Increase (reduction) in estimates of net ultimate losses	19,175	14,963	36,481	29,268
Increase (reduction) in provisions for unallocated LAE	0	(105)	0	11
Amortization of fair value adjustments	0	0	0	0
Net incurred losses and LAE, current period	19,175	14,858	36,481	29,279
Net premiums written	34,583	31,327	76,077	73,246
Total
Net losses paid	19,347	12,821	36,877	26,494
Net change in case and LAE reserves	(3,442)	(1,121)	448	(527)
Net change in IBNR reserves	1,855	(3,542)	146	(5,346)
Amortization of deferred charges	0	0	0	0
Increase (reduction) in estimates of net ultimate losses	17,760	8,158	37,471	20,621
Reduction in provisions for bad debt	0	0	0	0
Increase (reduction) in provisions for unallocated LAE	2	(56)	2	(64)
Amortization of fair value adjustments	(836)	87	(3,375)	120
Changes in fair value - fair value option	0	0	0	0
Total net incurred losses and LAE	16,926	8,189	34,098	20,677
StarStone
Prior Period
Net losses paid	85,888	53,517	173,575	137,497
Net change in case and LAE reserves	(21,405)	(16,621)	(35,622)	(41,464)
Net change in IBNR reserves	(46,738)	(35,828)	(120,128)	(94,765)
Increase (reduction) in estimates of net ultimate losses	17,745	1,068	17,825	1,268
Increase (reduction) in provisions for unallocated LAE	(1,189)	(1,205)	(3,290)	(3,131)
Amortization of fair value adjustments	(101)	(111)	(242)	(634)
Net incurred losses and LAE, prior period	16,455	(248)	14,293	(2,497)
Current Period
Net losses paid	19,419	10,645	20,367	14,861
Net change in case and LAE reserves	47,246	24,766	56,988	40,250
Net change in IBNR reserves	59,480	29,178	123,999	77,963
Increase (reduction) in estimates of net ultimate losses	126,145	64,589	201,354	133,074
Increase (reduction) in provisions for unallocated LAE	3,427	1,492	5,720	3,417
Amortization of fair value adjustments	0	0	0	0
Net incurred losses and LAE, current period	129,572	66,081	207,074	136,491
Net premiums written	219,238	115,534	399,801	234,400
Total
Net losses paid	105,307	64,162	193,942	152,358
Net change in case and LAE reserves	25,841	8,145	21,366	(1,214)
Net change in IBNR reserves	12,742	(6,650)	3,871	(16,802)
Amortization of deferred charges	0	0	0	0
Increase (reduction) in estimates of net ultimate losses	143,890	65,657	219,179	134,342
Reduction in provisions for bad debt	0	0	0	0
Increase (reduction) in provisions for unallocated LAE	2,238	287	2,430	286
Amortization of fair value adjustments	(101)	(111)	(242)	(634)
Changes in fair value - fair value option	0	0	0	0
Total net incurred losses and LAE	146,027	$ 65,833	221,367	133,994
Workers Compensation Insurance Product Line [Member] \| Non-life Run-off
Prior Period
Net change in case and IBNR reserves	$ (286,500)		$ (564,500)	$ (352,200)

Losses and Loss Adjustment Expenses - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Effects of Reinsurance [Line Items]
Net incurred losses and LAE	$ 92,819	$ 9,620	$ 112,353	$ 87,512
Net incurred losses and LAE, current period	153,860	81,400	249,014	166,945
Prior periods	(61,041)	(71,780)	(136,661)	(79,433)
Net losses paid	290,491	205,222	641,137	454,944
Net premiums written	253,219	149,548	476,366	311,607
Amortization of deferred charge	3,718	5,130	8,799	6,076
Non-life Run-off
Effects of Reinsurance [Line Items]
Net incurred losses and LAE	(70,134)	(64,402)	(143,112)	(67,159)
Net incurred losses and LAE, current period	5,113	461	5,459	1,175
Prior periods	(75,247)	(64,863)	(148,571)	(68,334)
Increase (reduction) in estimates of net ultimate losses	(87,087)	(40,585)	(107,365)	(45,520)
Increase (reduction) in provisions for unallocated LAE	(9,311)	(10,989)	(24,263)	(25,354)
Decrease in fair value - fair value option, Prior Period	(17,233)	13,232	23,008	(1,250)
Amortization of fair value adjustments	3,918	678	6,065	2,025
Net change in case and IBNR reserves		(190,000)
Net losses paid	195,721	144,282	448,304	300,613
Amortization of deferred charges	3,718	5,130	8,799
Net premiums written	(1,661)	1,905	(1,561)	1,986
Amortization of deferred charge	3,718	$ 5,130	8,799	6,076
Non-life Run-off \| Workers Compensation Business
Effects of Reinsurance [Line Items]
Net change in case and IBNR reserves	$ (286,500)		$ (564,500)	$ (352,200)

Policy Benefits for Life Contracts (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Insurance [Abstract]
Policy benefits for life contracts	$ 108,963	$ 117,207

Premiums Written and Earned - Schedule of Net Premiums Written and Earned (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Effects of Reinsurance [Line Items]
Gross, premiums written	$ 342,950	$ 260,933	$ 705,798	$ 536,365
Ceded, premiums written	(89,731)	(111,385)	(229,432)	(224,758)
Net, premiums written	253,219	149,548	476,366	311,607
Gross, premiums earned	309,247	254,909	598,024	499,568
Ceded, premiums earned	(80,435)	(99,338)	(198,993)	(195,099)
Net, premiums earned	228,812	155,571	399,031	304,469
Non-life Run-off
Effects of Reinsurance [Line Items]
Gross, premiums written	(938)	1,222	6,442	2,205
Ceded, premiums written	(723)	683	(8,003)	(219)
Net, premiums written	(1,661)	1,905	(1,561)	1,986
Gross, premiums earned	23,188	4,710	36,298	6,008
Ceded, premiums earned	(13,579)	(1,345)	(19,511)	(2,567)
Net, premiums earned	9,609	3,365	16,787	3,441
Atrium
Effects of Reinsurance [Line Items]
Gross, premiums written	41,560	34,565	91,002	80,978
Ceded, premiums written	(6,977)	(3,238)	(14,925)	(7,732)
Net, premiums written	34,583	31,327	76,077	73,246
Gross, premiums earned	39,795	35,822	79,469	72,042
Ceded, premiums earned	(5,273)	(3,442)	(9,724)	(7,442)
Net, premiums earned	34,522	32,380	69,745	64,600
StarStone
Effects of Reinsurance [Line Items]
Gross, premiums written	301,353	224,564	606,342	451,100
Ceded, premiums written	(82,115)	(109,030)	(206,541)	(216,700)
Net, premiums written	219,238	115,534	399,801	234,400
Gross, premiums earned	245,284	212,720	480,227	418,304
Ceded, premiums earned	(61,663)	(94,169)	(169,780)	(184,345)
Net, premiums earned	183,621	118,551	310,447	233,959
Other Segments
Effects of Reinsurance [Line Items]
Gross, premiums written	975	582	2,012	2,082
Ceded, premiums written	84	200	37	(107)
Net, premiums written	1,059	782	2,049	1,975
Gross, premiums earned	980	1,657	2,030	3,214
Ceded, premiums earned	80	(382)	22	(745)
Net, premiums earned	$ 1,060	$ 1,275	$ 2,052	$ 2,469

Goodwill and Intangible Assets - Schedule of Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Goodwill [Roll Forward]
Goodwill, Beginning balance			$ 73,071
Goodwill, Acquired during the period			41,736
Goodwill, Ending balance	$ 114,807		114,807
Finite-lived Intangible Assets [Roll Forward]
Intangible assets with a definite life, Beginning balance			20,487
Intangible assets with a definite life, Acquired during the period			0
Intangible assets with a definite life, Amortization			(2,460)
Intangible assets with a definite life, Ending balance	18,027		18,027
Indefinite-lived Intangible Assets [Roll Forward]
Intangible assets with an indefinite life, Beginning balance			87,031
Intangible assets with an indefinite life, Acquired during the period			0
Intangible assets with an indefinite life, Ending balance	87,031		87,031
Goodwill and Intangible Assets [Roll Forward]
Goodwill and intangible assets, Beginning Balance			180,589
Goodwill and intangible assets, Acquired during the period			41,736
Intangible assets with a definite life, Amortization			(2,460)
Goodwill and intangible assets, Ending balance	219,865		219,865
Movement in Intangible Assets Arising from Insurance Contracts Acquired in Business Combination [Roll Forward]
Intangible assets with a definite life - FVA, Beginning balance			140,393
Intangible assets with a definite life - FVA, Acquired during the period			0
Intangible assets with a definite life - FVA, Amortization			(2,786)
Intangible assets with a definite life - FVA, Ending balance	137,607		137,607
Deferred Charges [Roll Forward]
Less: deferred charges on retroactive reinsurance	75,111	$ 93,605	80,192	$ 94,551
Other assets - Deferred Charges, Acquired during the period			0
Other assets - Deferred Charges, Amortization	(3,718)	(5,130)	(8,799)	(6,076)
Plus: deferred charges on retroactive reinsurance	$ 71,393	$ 88,475	$ 71,393	$ 88,475

Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Goodwill, Intangible Assets, Intangible Assets Arising from Insurance Contracts Acquired in Business Combination, and Deferred Charges Disclosure [Abstract]
Amortization of intangible assets	$ 4.5	$ 0.7	$ 5.2	$ 2.2

Goodwill and Intangible Assets - Summary of Gross Carrying Value, Accumulated Amortization and Net Carrying Value of Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Fair value adjustments:
Gross Carrying Value	$ 320,241		$ 320,241
Accumulated Amortization	(182,634)		(179,848)
Net Carrying Value	137,607		140,393
Other:
Gross Carrying Value	42,000		42,000
Accumulated Amortization	(23,973)		(21,513)
Net Carrying Value	18,027		20,487
Indefinite-lived Intangible Assets [Line Items]
Intangible assets with an indefinite life, Carrying Value	87,031		87,031
Deferred charges on retroactive reinsurance, Gross Carrying Value	278,643		278,643
Deferred charges on retroactive reinsurance, Accumulated Amortization	(207,250)		(198,451)
Deferred charges on retroactive reinsurance, Net Carrying Value	71,393	$ 75,111	80,192	$ 88,475	$ 93,605	$ 94,551
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
Losses and LAE liabilities
Fair value adjustments:
Gross Carrying Value	462,455		462,455
Accumulated Amortization	(347,407)		(345,449)
Net Carrying Value	115,048		117,006
Reinsurance balances recoverable
Fair value adjustments:
Gross Carrying Value	(179,219)		(179,219)
Accumulated Amortization	164,887		165,579
Net Carrying Value	(14,332)		(13,640)
Fair Value Adjustment Intangible, Other Asset [Member]
Fair value adjustments:
Gross Carrying Value	(48,840)		(48,840)
Accumulated Amortization	706		440
Net Carrying Value	(48,134)		(48,400)
Fair Value Adjustment Intangible, Other Liabilities [Member]
Fair value adjustments:
Gross Carrying Value	85,845		85,845
Accumulated Amortization	(820)		(418)
Net Carrying Value	85,025		85,427
Distribution channel
Other:
Gross Carrying Value	20,000		20,000
Accumulated Amortization	(6,110)		(5,444)
Net Carrying Value	13,890		14,556
Technology
Other:
Gross Carrying Value	15,000		15,000
Accumulated Amortization	(14,654)		(13,210)
Net Carrying Value	346		1,790
Brand
Other:
Gross Carrying Value	7,000		7,000
Accumulated Amortization	(3,209)		(2,859)
Net Carrying Value	$ 3,791		$ 4,141

Debt Obligations - Amounts Outstanding and Accrued Interest (Detail) - USD ($)				3 Months Ended		6 Months Ended
	Mar. 10, 2017	Nov. 18, 2016	Sep. 16, 2014	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Total debt obligations				$ 439,610,000		$ 439,610,000		$ 646,689,000
Interest expense				8,700,000	$ 6,800,000	16,100,000	$ 13,000,000
Senior Notes \| Senior Notes Due 2022
Debt Instrument [Line Items]
Term	5 years
Aggregate principal amount	$ 350,000,000			350,000,000		350,000,000		350,000,000
Less: Unamortized debt issuance costs				(2,285,000)		(2,285,000)		(2,484,000)
Total debt obligations				347,715,000		347,715,000		347,516,000
Line of Credit \| EGL Revolving Credit Facility
Debt Instrument [Line Items]
Term			5 years
Total debt obligations				91,895,000		91,895,000		225,110,000
Line of Credit \| EGL Term Loan Facility
Debt Instrument [Line Items]
Term		3 years
Total debt obligations				$ 0		$ 0		$ 74,063,000

Debt Obligations - Additional Information (Detail) € in Millions				1 Months Ended	6 Months Ended
	Mar. 10, 2017 USD ($)	Nov. 18, 2016 USD ($)	Sep. 16, 2014	Aug. 01, 2018 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 EUR (€)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 EUR (€)
Line of Credit Facility [Line Items]
Receipt of loans					$ 374,069,000	$ 489,100,000
Repayment of loans					(578,062,000)	$ (528,500,000)
Debt obligations					439,610,000			$ 646,689,000
Net investment hedging
Line of Credit Facility [Line Items]
Derivative notional amount					70,100,000		€ 60.0	60,100,000	€ 50.0
Senior Notes \| Senior Notes Due 2022
Line of Credit Facility [Line Items]
Aggregate principal amount	$ 350,000,000				$ 350,000,000			350,000,000
Stated interest rate	4.50%				4.50%		4.50%
Redemption price percentage	100.00%
Payments of debt issuance costs	$ 2,900,000
Term	5 years
Debt obligations					$ 347,715,000			347,516,000
Line of Credit \| EGL Revolving Credit Facility
Line of Credit Facility [Line Items]
Term			5 years
Maximum borrowing capacity					831,300,000
Line of credit facility, remaining borrowing capacity					739,400,000
Debt obligations					91,895,000			225,110,000
Line of Credit \| EGL Revolving Credit Facility \| Subsequent Event
Line of Credit Facility [Line Items]
Maximum borrowing capacity				$ 600,000,000
Line of credit facility, remaining borrowing capacity				522,000,000
Repayment of loans				$ (13,900,000)
Line of Credit \| EGL Term Loan Facility
Line of Credit Facility [Line Items]
Term		3 years
Maximum borrowing capacity		$ 75,000,000
Debt obligations					$ 0			$ 74,063,000

Noncontrolling Interests - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Noncontrolling Interest [Line Items]
Noncontrolling interest	$ 9,727	$ 9,264
Trident \| Subsidiaries
Noncontrolling Interest [Line Items]
Interest owned by an entity (percent)	39.30%	39.30%
Dowling \| Subsidiaries
Noncontrolling Interest [Line Items]
Interest owned by an entity (percent)	1.70%	1.70%

Noncontrolling Interests - Carrying Amount of Equity Attributable to Noncontrolling Interest (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Increase (Decrease) in Redeemable Noncontrolling Interest [Roll Forward]
Balance at beginning of period	$ 479,606	$ 454,522
Dividends paid	0	(27,458)
Net earnings (losses) attributable to RNCI	(8,021)	19,619
Accumulated other comprehensive earnings (losses) attributable to RNCI	(381)	1,945
Change in redemption value of RNCI	(111)	30,978
Balance at end of period	$ 471,093	$ 479,606

Share Capital Share Capital - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands				6 Months Ended
	Jul. 31, 2018	Jun. 28, 2018	May 14, 2018	Jun. 30, 2018	Jun. 30, 2017
Class of Stock [Line Items]
Net proceeds from issuance of stock				$ 389,482	$ 0
Public Stock Offering \| Series D Preferred Stock
Class of Stock [Line Items]
Amount raised through public offering		$ 400,000
Shares issued in public offering (in shares)		16,000
Dividend rate, percentage		7.00%
Depositary interest in preferred shares, per share		$ 0.001
Shares issued in public offering (in depositary shares)		16,000,000
Preferred stock, par value (in dollars per share)		$ 1
Liquidation preference (in dollars per share)		25,000
Liquidiation preference (in dollars per depositary share)		$ 25
Net proceeds from issuance of stock		$ 389,500
Dividends in arrears per share (in dollars per share)		$ 1,750
Dividends in arrears per share (in dollars per depositary share)		$ 1.75
KaylaRe
Class of Stock [Line Items]
Shares issued (in shares)			2,007,017
Ordinary Shares \| KaylaRe
Class of Stock [Line Items]
Shares issued (in shares)			1,501,778
Series E Non-Voting Convertible Ordinary Shares \| KaylaRe
Class of Stock [Line Items]
Shares issued (in shares)			505,239
LIBOR \| Public Stock Offering \| Series D Preferred Stock
Class of Stock [Line Items]
Basis spread on variable rate		4.015%
Subsequent Event \| Series D Preferred Stock
Class of Stock [Line Items]
Delcared cash dividends (in dollars per share)	$ 320.83
Declared cash dividends (in dollars per depositary share)	$ 0.32083

Earnings Per Share - Comparison of Basic and Diluted Earnings per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator:
Net earnings (loss) from continuing operations	$ 8,244	$ 95,057	$ (32,966)	$ 149,366
Net loss from discontinued operations	0	(4,871)	0	(4,500)
NET EARNINGS (LOSS) AVAILABLE (ATTRIBUTABLE) TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$ 8,244	$ 90,186	$ (32,966)	$ 144,866
Weighted-average ordinary shares outstanding — basic (in shares)	20,462,788	19,387,650	19,938,815	19,381,225
Effect of dilutive securities:
Share-based compensation plans (in shares)	128,232	53,720	122,471	54,182
Warrants (in shares)	80,212	70,059	79,081	70,670
Weighted-average ordinary shares outstanding — diluted (in shares)	20,671,232	19,511,429	20,140,367	19,506,077
Basic:
Net earnings (loss) from continuing operations (in dollars per share)	$ 0.40	$ 4.90	$ (1.65)	$ 7.71
Net loss from discontinued operations (in dollars per share)	0.00	(0.25)	0.00	(0.23)
Net earnings (loss) per ordinary share (in dollars per share)	0.40	4.65	(1.65)	7.48
Diluted:
Net earnings (loss) from continuing operations (in dollars per share)	0.40	4.87	(1.65)	7.66
Net loss from discontinued operations (in dollars per share)	0.00	(0.25)	0.00	(0.23)
Net earnings (loss) per ordinary share (in dollars per share)	$ 0.40	$ 4.62	$ (1.65)	$ 7.43

Share-Based Compensation and Pensions (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pension expense	$ 3,184	$ 3,182	$ 5,822	$ 5,485
Restricted Stock And Stock Appreciation Rights SARS
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	4,454	6,155	10,519	9,979
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 127	$ 58	$ 210	$ 166

Taxation - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
Taxation - Additional Information (Detail) - USD ($)	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective tax rate	104.10%	4.20%	(10.40%)	1.00%
Statutory rate			0.00%
Unrecognized tax benefits	$ 0		$ 0		$ 0

Related Party Transactions - Stone Point Capital LLC (Details) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jul. 31, 2012 shares	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Nov. 06, 2013 general_partner
Related Party Transaction [Line Items]
Redeemable noncontrolling interest	$ 471,093			$ 471,093		$ 479,606	$ 454,522
Related Party, Consolidated Balance Sheet [Abstract]
Other investments, at fair value	1,768,333			1,768,333		913,392
Investments in registered investment companies affiliated with entities owned by Trident	130,404			130,404		106,603
Related Party, Consolidated Statement of Earnings [Abstract]
Net realized and unrealized gains (loss)	54,418	$ (51,877)		197,448	$ (110,396)
CLO equities
Related Party, Consolidated Balance Sheet [Abstract]
Other investments, at fair value	53,840			53,840		56,765
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_partner								1
Number of general partners \| general_partner								4
Redeemable noncontrolling interest	451,490			451,490		459,649
Related Party, Consolidated Balance Sheet [Abstract]
Other investments, at fair value	366,279			366,279		255,905
Investments in registered investment companies affiliated with entities owned by Trident	40,422			40,422		22,060
Trident \| Affiliated Entity \| Fund Investments
Related Party, Consolidated Statement of Earnings [Abstract]
Net realized and unrealized gains (loss)	3,778	4,682		2,252	11,650
Trident \| Affiliated Entity \| Registered Investment Companies
Related Party, Consolidated Statement of Earnings [Abstract]
Net realized and unrealized gains (loss)	(344)	171		(6,549)	(5,037)
Interest income	828	771		1,910	1,274
Eagle Point Credit and PRIMA Capital Advisors \| Affiliated Entity
Related Party, Consolidated Balance Sheet [Abstract]
Separate account assets	216,695			216,695		183,448
Eagle Point Credit and PRIMA Capital Advisors \| Affiliated Entity \| Management Fee
Related Party, Consolidated Statement of Earnings [Abstract]
Management fees	(227)	(151)		(454)	(291)
Sound Point Capital \| Affiliated Entity
Related Party, Consolidated Balance Sheet [Abstract]
Other investments, at fair value	20,097			20,097		27,429
Separate account assets	65,182			65,182		63,572
Related Party, Consolidated Statement of Earnings [Abstract]
Net realized and unrealized gains (loss)	291	433		(238)	794
Sound Point Capital \| Affiliated Entity \| CLO equities
Related Party, Consolidated Balance Sheet [Abstract]
Other investments, at fair value	17,137			17,137		$ 17,760
Related Party, Consolidated Statement of Earnings [Abstract]
Net realized and unrealized gains (loss)	(392)	(383)		(623)	2,494
Interest income	1,179	1,292		2,489	2,479
Sound Point Capital \| Affiliated Entity \| Management Fee
Related Party, Consolidated Statement of Earnings [Abstract]
Management fees	$ (80)	$ (81)		$ (161)	$ (153)
Stone Point \| Affiliated Entity
Related Party Transaction [Line Items]
Ownership percentage	9.10%			9.10%

Related Party Transactions - CPPIB (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Nov. 30, 2016
Affiliated Entity \| CPPIB and Management of Wilton Re
Related Party Transaction [Line Items]
Reinsurance recoverables	$ 6,992	$ 7,003
Affiliated Entity \| CPPIB LP
Related Party Transaction [Line Items]
Ownership percentage			4.10%
Canada Pension Plan Investment Board \| Affiliated Entity
Related Party Transaction [Line Items]
Ownership percentage			8.40%
Economic interest percentage	17.90%
CPPIB and Management of Wilton Re \| Wilton Re
Related Party Transaction [Line Items]
Ownership percentage by parent	100.00%

Related Party Transactions - KaylaRe (Details) - USD ($) $ in Thousands			3 Months Ended		6 Months Ended
	May 14, 2018	Dec. 15, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party, Consolidated Balance Sheet [Abstract]
Reinsurance balances recoverable			$ 1,994,811		$ 1,994,811			$ 2,021,030
Prepaid insurance premiums			14,859		14,859			13,747
Insurance and reinsurance balances payable			354,100		354,100			236,697
Related Party, Consolidated Statement of Earnings [Abstract]
Fee income due to Enstar Limited					1,453	$ 0
Ceded premium earned			80,435	$ 99,338	198,993	195,099
Net incurred losses and LAE			92,819	9,620	112,353	87,512
Acquisition costs			$ 53,334	$ 30,355	83,442	51,176
KaylaRe
Related Party Transaction [Line Items]
Initial capital raise		$ 620,000
KaylaRe \| Equity Method Investee
Related Party, Consolidated Balance Sheet [Abstract]
Reinsurance balances recoverable								357,355
Prepaid insurance premiums								116,356
Funds held								174,181
Insurance and reinsurance balances payable								232,884
Ceded acquisition costs								36,070
KaylaRe transactions with Starstone
Related Party, Consolidated Statement of Earnings [Abstract]
Ceded premium earned					52,651	113,354
Net incurred losses and LAE					31,654	60,156
Acquisition costs					$ 18,774	45,373
KaylaRe
Related Party Transaction [Line Items]
Ownership percentage			48.20%		48.20%
Carrying value of previously held equity method investment prior to the close of the transaction							$ 320,130	$ 309,800
Subsidiaries \| KaylaRe transactions with Fitzwilliam
Transactions Under Reinsurance Agreement [Abstract]
Profit Commission					$ 0	$ 7,816
KaylaRe
Related Party Transaction [Line Items]
Shares issued (in shares)	2,007,017
Ordinary Shares \| KaylaRe
Related Party Transaction [Line Items]
Shares issued (in shares)	1,501,778
Ordinary Shares \| KaylaRe \| Hillhouse
Related Party Transaction [Line Items]
Shares issued (in shares)	1,204,353
Ordinary Shares \| KaylaRe \| Trident
Related Party Transaction [Line Items]
Shares issued (in shares)	285,986
Preferred Shares: \| KaylaRe
Related Party Transaction [Line Items]
Shares issued (in shares)	505,239
Preferred Shares: \| KaylaRe \| Hillhouse
Related Party Transaction [Line Items]
Shares issued (in shares)	505,239
Preferred Shares: \| KaylaRe \| Minority Shareholder
Related Party Transaction [Line Items]
Shares issued (in shares)	11,439
Starstone \| KaylaRe
Related Party Transaction [Line Items]
Percentage of business reinsured					35.00%
Fitzwilliam \| Subsidiaries \| KaylaRe
Related Party Transaction [Line Items]
Ceded reinsurance receivables									$ 177,200

Related Party Transactions - Hillhouse (Details) - USD ($) $ in Thousands	3 Months Ended		4 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	May 14, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Other investments	$ 1,768,333			$ 1,768,333		$ 913,392
Additional subscriptions				462,336	$ 67,516
Net realized and unrealized gains (losses)	$ (54,418)	$ 51,877		$ (197,448)	$ 110,396
Hillhouse Affiliates \| Affiliated Entity
Related Party Transaction [Line Items]
Ownership percentage	9.70%			9.70%
Economic interest percentage	17.10%			17.10%
KaylaRe \| Affiliated Entity
Related Party Transaction [Line Items]
Additional subscriptions				$ 231,600
Hillhouse \| KaylaRe \| Affiliated Entity
Related Party Transaction [Line Items]
Other investments	$ 0			0		456,660
Unrealized gain on investments			$ 102,600
Additional subscriptions				202,100
Net realized and unrealized gains (losses)	10,850			22,939
Subsidiaries \| Hillhouse \| Cavello Bay
Related Party Transaction [Line Items]
Other investments	$ 703,986			$ 703,986		$ 0

Related Party Transactions - Monument (Details) $ in Thousands, € in Millions	3 Months Ended		6 Months Ended		12 Months Ended	21 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2018 USD ($)	Aug. 29, 2017 USD ($)	Aug. 29, 2017 EUR (€)
Related Party Transaction [Line Items]
Loss on sale of subsidiary	$ 0	$ 9,609	$ 0	$ 9,609
Laguna \| Disposed of by sale
Related Party Transaction [Line Items]
Loss on sale of subsidiary				$ 9,600	$ 16,300
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax					(6,300)
Laguna \| Monument \| Disposed of by sale \| Affiliated Entity
Related Party Transaction [Line Items]
Disposal, consideration							$ 30,800	€ 25.6
Monument
Related Party Transaction [Line Items]
Contributed amount of common and preferred shares						$ 16,000
Ownership percentage	26.60%		26.60%			26.60%
Carrying value of previously held equity method investment prior to the close of the transaction	$ 21,871		$ 21,871		$ 15,960	$ 21,871

Related Party Transactions - Clear Spring (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Jan. 01, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Capitalized amount of investment	$ 56,000
Balances under StarStone quota share:
Reinsurance balances recoverable		$ 1,994,811		$ 1,994,811			$ 2,021,030
Prepaid insurance premiums		14,859		14,859			13,747
Ceded payable		15,925		15,925			13,964
Losses and LAE
Losses and LAE		8,608,387	$ 7,641,384	8,608,387	$ 7,641,384	$ 8,986,070	7,398,088	$ 7,760,587	$ 5,987,867
Unearned reinsurance premiums		754,046		754,046			583,197
Funds held		259,432		259,432			175,383
Balances under StarStone quota share:
Ceded premium earned		80,435	99,338	198,993	195,099
Acquisition costs		53,334	30,355	83,442	51,176
Balances under Cavello quota share:
Net incurred losses and LAE		$ 92,819	9,620	$ 112,353	87,512
Clear Spring \| Equity Method Investee
Related Party Transaction [Line Items]
Ownership percentage		20.00%		20.00%
Balances under StarStone quota share:
Reinsurance balances recoverable		$ 16,166		$ 16,166			9,053
Ceded acquisition costs		3,545		3,545			3,186
Starstone \| Clear Spring
Related Party Transaction [Line Items]
Carrying value of previously held equity method investment prior to the close of the transaction		10,565		10,565			10,596
Percentage of business reinsured	33.30%
Balances under StarStone quota share:
Ceded premium earned		7,636	0	14,638	0
Net incurred losses and LAE		3,044	0	8,606	0
Acquisition costs		2,129	0	3,911	0
Starstone \| Cavello Bay
Related Party Transaction [Line Items]
Percentage of business reinsured	25.00%
Cavello Bay \| Clear Spring
Losses and LAE
Losses and LAE		554		554			0
Unearned reinsurance premiums		253		253			3,437
Funds held		1,400		1,400			$ 5,095
Balances under StarStone quota share:
Acquisition costs		91	0	555	0
Balances under Cavello quota share:
Premium earned		158	0	1,909	0
Net incurred losses and LAE		$ (629)	$ 0	$ 761	$ 0

Related Party Transactions - AmTrust (Details) - Subsequent Event - Affiliated Entity $ in Millions	Jul. 23, 2018 USD ($)
Evergreen Parent L.P. \| AmTrust Financial Services, Inc.
Related Party Transaction [Line Items]
Ownership percentage	45.00%
Evergreen Parent L.P.
Related Party Transaction [Line Items]
Ownership percentage	6.20%
Purchase amount of equity interest	$ 200.0
Capital units ownership percentage	7.40%

Related Party Transactions - Citco (Details) - USD ($) $ in Thousands	1 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017
Related Party Transaction [Line Items]
Indirect investment acquired		$ 462,336	$ 67,516
Trident \| Citco III Limited \| Affiliated Entity
Related Party Transaction [Line Items]
Indirect investment acquired	$ 50,000
Ownership percentage	3.40%	3.40%

Commitments and Contingencies - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2018	Feb. 08, 2018	Dec. 31, 2017
Guarantor Obligations [Line Items]
Funds held by reinsured companies	$ 259,432,000		$ 175,383,000
Concentration of credit risk, counterparty credit exposure	0.10
Commitments, unfunded	200,000,000
Asbestos personal injury liabilities
Guarantor Obligations [Line Items]
Indemnity and defense costs	192,200,000		205,700,000
Insurance recoveries receivable	117,900,000		122,300,000
Asbestos personal injury liabilities \| Dana properties
Guarantor Obligations [Line Items]
Indemnity and defense costs	2,200,000		2,200,000
Limited Parental Guarantee
Guarantor Obligations [Line Items]
Parental guarantees	618,700,000		$ 630,700,000
US
Guarantor Obligations [Line Items]
Concentration of credit risk, counterparty credit exposure	843,200,000
United Kingdom
Guarantor Obligations [Line Items]
Concentration of credit risk, counterparty credit exposure	388,100,000
Reinsurance Recoverables \| Reinsurer Concentration Risk
Guarantor Obligations [Line Items]
Funds held by reinsured companies	1,051,300,000
Line of Credit \| FAL Facility \| Letters of Credit
Guarantor Obligations [Line Items]
Maximum borrowing capacity	$ 295,000,000	$ 325,000,000
Higher borrowing capacity option		$ 400,000,000

Segment Information - Additional Information (Detail)	6 Months Ended
Segment Information - Additional Information (Detail)	Jun. 30, 2018 Segment
Segment Reporting [Abstract]
Number of segments	3

Segment Information - Summary of Operations by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Gross premiums written	$ 342,950	$ 260,933	$ 705,798	$ 536,365
Net premiums written	253,219	149,548	476,366	311,607
Net premiums earned	228,812	155,571	399,031	304,469
Net incurred losses and LAE	(92,819)	(9,620)	(112,353)	(87,512)
Life and Annuity Policy Benefits	160	(4,289)	206	(3,988)
Acquisition costs	(53,334)	(30,355)	(83,442)	(51,176)
Operating expenses	(76,650)	(70,931)	(153,787)	(137,801)
Underwriting income (loss)	6,169	40,376	49,655	23,992
Net investment income	66,469	49,417	132,788	98,156
Net realized and unrealized gains (losses)	(54,418)	51,877	(197,448)	110,396
Other income	6,294	10,856	22,934	23,054
Corporate expenses	(25,962)	(35,559)	(44,085)	(71,157)
Interest income (expense)	(8,922)	(7,573)	(16,933)	(14,441)
Net foreign exchange gains (losses)	(5,519)	7,122	349	10,837
Loss on sale of subsidiary	0	(9,609)	0	(9,609)
EARNINGS (LOSS) BEFORE INCOME TAXES	3,501	111,330	(36,755)	180,135
INCOME TAXES	(3,646)	(4,731)	(3,818)	(1,802)
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	(145)	106,599	(40,573)	178,333
NET LOSS FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES	0	(4,871)	0	(4,500)
NET EARNINGS (LOSS)	(145)	101,728	(40,573)	173,833
Less: Net (earnings) losses attributable to noncontrolling interest	8,389	(11,542)	7,607	(28,967)
Net Income (Loss) Available to Common Stockholders, Basic	8,244	90,186	(32,966)	144,866
Non-life Run-off
Segment Reporting Information [Line Items]
Gross premiums written	(938)	1,222	6,442	2,205
Net premiums written	(1,661)	1,905	(1,561)	1,986
Net premiums earned	9,609	3,365	16,787	3,441
Net incurred losses and LAE	70,134	64,402	143,112	67,159
Life and Annuity Policy Benefits	0	0	0	0
Acquisition costs	(3,214)	946	(4,684)	546
Operating expenses	(38,378)	(31,668)	(76,781)	(61,110)
Underwriting income (loss)	38,151	37,045	78,434	10,036
Net investment income	57,291	39,572	108,942	75,301
Net realized and unrealized gains (losses)	(46,027)	50,556	(172,323)	102,114
Other income	6,311	10,769	23,566	22,697
Corporate expenses	(13,387)	(22,793)	(22,020)	(46,142)
Interest income (expense)	(10,081)	(7,646)	(18,611)	(14,327)
Net foreign exchange gains (losses)	(6,958)	2,160	219	2,937
Loss on sale of subsidiary		0		0
EARNINGS (LOSS) BEFORE INCOME TAXES	43,703	116,160	7,154	166,282
INCOME TAXES	(1,219)	(3,679)	(102)	(4,639)
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	42,484	112,481	7,052	161,643
NET LOSS FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES		0		0
NET EARNINGS (LOSS)		112,481		161,643
Less: Net (earnings) losses attributable to noncontrolling interest	(1,094)	(2,621)	(2,523)	(10,630)
Net Income (Loss) Available to Common Stockholders, Basic	41,390	109,860	4,529	151,013
Atrium
Segment Reporting Information [Line Items]
Gross premiums written	41,560	34,565	91,002	80,978
Net premiums written	34,583	31,327	76,077	73,246
Net premiums earned	34,522	32,380	69,745	64,600
Net incurred losses and LAE	(16,926)	(8,189)	(34,098)	(20,677)
Life and Annuity Policy Benefits	0	0	0	0
Acquisition costs	(12,716)	(12,057)	(24,781)	(22,829)
Operating expenses	(4,130)	(6,313)	(8,307)	(9,720)
Underwriting income (loss)	750	5,821	2,559	11,374
Net investment income	1,285	861	2,470	1,985
Net realized and unrealized gains (losses)	(680)	474	(2,083)	892
Other income	56	50	120	119
Corporate expenses	(1,838)	(3,637)	(2,313)	(7,441)
Interest income (expense)	0	(265)	0	(536)
Net foreign exchange gains (losses)	47	3,480	1,000	4,312
Loss on sale of subsidiary		0		0
EARNINGS (LOSS) BEFORE INCOME TAXES	3,391	7,894	7,051	13,523
INCOME TAXES	(739)	(368)	(1,019)	(724)
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	2,652	7,526	6,032	12,799
NET LOSS FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES		0		0
NET EARNINGS (LOSS)		7,526		12,799
Less: Net (earnings) losses attributable to noncontrolling interest	(1,121)	(3,087)	(2,532)	(5,250)
Net Income (Loss) Available to Common Stockholders, Basic	$ 1,531	$ 4,439	$ 3,500	$ 7,549
Underwriting Loss Ratio	49.00%	25.30%	48.90%	32.00%
Underwriting Acquisition Expense Ratio	36.80%	37.20%	35.50%	35.30%
Underwriting Other Operating Expense Ratio	12.00%	19.50%	11.90%	15.10%
Underwriting Combined Ratio	97.80%	82.00%	96.30%	82.40%
StarStone
Segment Reporting Information [Line Items]
Gross premiums written	$ 301,353	$ 224,564	$ 606,342	$ 451,100
Net premiums written	219,238	115,534	399,801	234,400
Net premiums earned	183,621	118,551	310,447	233,959
Net incurred losses and LAE	(146,027)	(65,833)	(221,367)	(133,994)
Life and Annuity Policy Benefits	0	0	0	0
Acquisition costs	(37,271)	(17,698)	(53,696)	(28,312)
Operating expenses	(34,142)	(32,950)	(68,699)	(66,971)
Underwriting income (loss)	(33,819)	2,070	(33,315)	4,682
Net investment income	8,745	7,189	16,446	12,638
Net realized and unrealized gains (losses)	(3,181)	7,209	(16,139)	13,908
Other income	(600)	33	(549)	79
Corporate expenses	0	0	0	0
Interest income (expense)	(6)	(644)	(547)	(1,266)
Net foreign exchange gains (losses)	1,573	815	478	2,708
Loss on sale of subsidiary		0		0
EARNINGS (LOSS) BEFORE INCOME TAXES	(30,434)	15,042	(34,582)	28,499
INCOME TAXES	(1,688)	(679)	(2,686)	3,570
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	(32,122)	14,363	(37,268)	32,069
NET LOSS FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES		0		0
NET EARNINGS (LOSS)		14,363		32,069
Less: Net (earnings) losses attributable to noncontrolling interest	10,604	(5,834)	12,662	(13,087)
Net Income (Loss) Available to Common Stockholders, Basic	$ (21,518)	$ 8,529	$ (24,606)	$ 18,982
Underwriting Loss Ratio	79.50%	55.50%	71.30%	57.30%
Underwriting Acquisition Expense Ratio	20.30%	14.90%	17.30%	12.10%
Underwriting Other Operating Expense Ratio	18.60%	27.90%	22.10%	28.60%
Underwriting Combined Ratio	118.40%	98.30%	110.70%	98.00%
Other Segments
Segment Reporting Information [Line Items]
Gross premiums written	$ 975	$ 582	$ 2,012	$ 2,082
Net premiums written	1,059	782	2,049	1,975
Net premiums earned	1,060	1,275	2,052	2,469
Net incurred losses and LAE	0	0	0	0
Life and Annuity Policy Benefits	160	(4,289)	206	(3,988)
Acquisition costs	(133)	(1,546)	(281)	(581)
Operating expenses	0	0	0	0
Underwriting income (loss)	1,087	(4,560)	1,977	(2,100)
Net investment income	(852)	1,795	4,930	8,232
Net realized and unrealized gains (losses)	(4,530)	(6,362)	(6,903)	(6,518)
Other income	527	4	(203)	159
Corporate expenses	(10,737)	(9,129)	(19,752)	(17,574)
Interest income (expense)	1,165	982	2,225	1,688
Net foreign exchange gains (losses)	(181)	667	(1,348)	880
Loss on sale of subsidiary		(9,609)		(9,609)
EARNINGS (LOSS) BEFORE INCOME TAXES	(13,159)	(27,766)	(16,378)	(28,169)
INCOME TAXES	0	(5)	(11)	(9)
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	(13,159)	(27,771)	(16,389)	(28,178)
NET LOSS FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES		(4,871)		(4,500)
NET EARNINGS (LOSS)		(32,642)		(32,678)
Less: Net (earnings) losses attributable to noncontrolling interest	0	0	0	0
Net Income (Loss) Available to Common Stockholders, Basic	(13,159)	(32,642)	(16,389)	(32,678)
Fees and commission income
Segment Reporting Information [Line Items]
Fees and commission income	8,352	18,667	16,683	30,581
Fees and commission income \| Non-life Run-off
Segment Reporting Information [Line Items]
Fees and commission income	4,487	10,817	9,385	19,540
Fees and commission income \| Atrium
Segment Reporting Information [Line Items]
Fees and commission income	3,865	8,070	7,298	11,442
Fees and commission income \| StarStone
Segment Reporting Information [Line Items]
Fees and commission income	0	0	0	1,166
Fees and commission income \| Other Segments
Segment Reporting Information [Line Items]
Fees and commission income	$ 0	$ (220)	$ 0	$ (1,567)

Segment Information - Summary of Company's Assets by Segment (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 15,203,212	$ 13,606,422
Non-life Run-off
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	11,997,250	10,368,105
Atrium
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	584,631	556,637
StarStone
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	3,113,207	3,128,725
Life and Annuities Segment
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ (491,876)	$ (447,045)

Investments - Credit Ratings of Fixed Maturity and Short-Term Investments, Trading (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 6,974,444
Fair Value	6,857,646
Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 295,457
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%
Trading and Available for Sale Securities \| Credit Rating Concentration Risk \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	4.30%
AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,762,248
AAA Rated \| Trading and Available for Sale Securities \| Credit Rating Concentration Risk \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	25.70%
AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,193,529
AA Rated \| Trading and Available for Sale Securities \| Credit Rating Concentration Risk \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	17.40%
A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 2,328,878
A Rated \| Trading and Available for Sale Securities \| Credit Rating Concentration Risk \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	34.00%
BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,260,796
BBB Rated \| Trading and Available for Sale Securities \| Credit Rating Concentration Risk \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	18.40%
Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 16,738
Not Rated \| Trading and Available for Sale Securities \| Credit Rating Concentration Risk
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
% of Total Investments	0.20%
U.S. government and agency
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 544,615
Fair Value	538,552
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	7.90%
U.S. government and agency \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 537,959
U.S. government and agency \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	593
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
Non-U.S. government
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	1,061,120
Fair Value	1,056,161
Non-U.S. government \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 5,955
Non-U.S. 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	15.40%
Non-U.S. government \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 375,722
Non-U.S. government \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	568,567
Non-U.S. government \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	46,510
Non-U.S. government \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	59,407
Non-U.S. 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	3,970,353
Fair Value	3,874,350
Corporate \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 105,329
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	56.50%
Corporate \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 169,098
Corporate \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	461,745
Corporate \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	2,073,323
Corporate \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	1,064,563
Corporate \| Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	292
Municipal
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	94,078
Fair Value	93,051
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	1.40%
Municipal \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 18,303
Municipal \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	58,518
Municipal \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	12,811
Municipal \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	3,419
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	304,267
Fair Value	306,043
Residential mortgage-backed \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 97,140
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	4.40%
Residential mortgage-backed \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 187,130
Residential mortgage-backed \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	4,046
Residential mortgage-backed \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	13,154
Residential mortgage-backed \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	410
Residential mortgage-backed \| Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	4,163
Commercial mortgage-backed
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	415,135
Fair Value	403,001
Commercial mortgage-backed \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 9,822
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	5.90%
Commercial mortgage-backed \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 210,884
Commercial mortgage-backed \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	47,233
Commercial mortgage-backed \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	65,830
Commercial mortgage-backed \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	57,420
Commercial mortgage-backed \| Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	11,812
Asset-backed
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	584,876
Fair Value	586,488
Asset-backed \| Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 77,211
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	8.50%
Asset-backed \| AAA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 263,152
Asset-backed \| AA Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	52,827
Asset-backed \| A Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	117,250
Asset-backed \| BBB Rated \| Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	75,577
Asset-backed \| Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 471