Enstar Group Limited (ESGR) 10-K 1 Mar 21 2020 FY Annual report Financial data

Cover page

Cover page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Feb. 25, 2021	Jun. 30, 2020
Document Information [Line Items]
Document Type	10-K
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Entity File Number	001-33289
Entity Registrant Name	Enstar Group LTD
Entity Incorporation, State or Country Code	D0
Entity Address, Address Line One	Windsor Place
Entity Address, Address Line Two	3rd Floor
Entity Address, Address Line Three	22 Queen Street
Entity Address, City or Town	Hamilton
Entity Address, Postal Zip Code	HM JX
Entity Address, Country	BM
City Area Code	441
Local Phone Number	292-3645
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1,630
Documents Incorporated by Reference	Portions of the registrant’s definitive proxy statement to be filed with the Securities and Exchange Commission pursuant to Regulation 14A relating to its 2021 annual general meeting of shareholders are incorporated by reference in Part III of this Form 10-K
Entity Central Index Key	0001363829
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Document Annual Report	true
Document Transition Report	false
Ordinary Shares
Document Information [Line Items]
Title of 12(b) Security	Ordinary shares, par value $1.00 per share
Trading Symbol	ESGR
Security Exchange Name	NASDAQ
Series D Preferred Shares
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares, Each Representing a 1/1,000th Interest in a 7.00%
Trading Symbol	ESGRP
Security Exchange Name	NASDAQ
Series E Preferred Shares
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares, Each Representing a 1/1,000th Interest in a 7.00%
Trading Symbol	ESGRO
Security Exchange Name	NASDAQ
Voting ordinary shares
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		18,585,678
Non-voting ordinary shares
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		3,509,682

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Available-for-sale, at fair value	$ 3,658,895	$ 1,666,387
Funds held - directly managed	1,074,890	1,187,552
Equities, at fair value	846,795	726,721
Other investments, at fair value	4,244,034	2,518,031
Equity method investments	832,295	326,277
Total investments (Note 6 and Note 12)	15,256,930	12,619,793
Cash and cash equivalents	901,152	624,472
Restricted cash and cash equivalents	471,964	346,877
Premiums receivable	405,793	491,511
Reinsurance balances recoverable on paid and unpaid losses (net of allowance: 2020 — $137,122) (Note 8)	1,568,333	1,485,616
Reinsurance balances recoverable on paid and unpaid losses, at fair value (Note 8 and Note 12)	520,830	695,518
Insurance balances recoverable (net of allowance: 2020 — $4,824) (Note 11)	249,652	448,855
Funds held by reinsured companies	635,819	475,732
Other assets	925,533	1,162,955
Assets held-for-sale (Note 5)	711,278	1,474,770
TOTAL ASSETS	21,647,284	19,826,099
LIABILITIES
Loss and loss adjustment expenses	8,140,362	7,247,282
Losses and loss adjustment expenses, fair value (Note 10 and Note 12)	2,452,920	2,621,122
Defendant asbestos and environmental liabilities (Note 11)	706,329	847,685
Insurance and reinsurance balances payable	494,412	420,546
Debt obligations (Note 15)	1,373,259	1,191,207
Other liabilities	942,905	994,584
Liabilities held-for-sale (Note 5)	483,657	1,208,531
TOTAL LIABILITIES	14,593,844	14,530,957
COMMITMENTS AND CONTINGENCIES (Note 23)
REDEEMABLE NONCONTROLLING INTEREST (Note 16)	365,436	438,791
Preferred Shares:
Treasury shares, at cost (Series C Preferred Shares 2020 and 2019: 388,571)	(421,559)	(421,559)
Joint Share Ownership Plan (voting ordinary shares, held in trust 2020: 565,630; 2019: 0)	(566)	0
Additional paid-in capital	1,836,074	1,836,778
Accumulated other comprehensive income	80,659	7,171
Retained earnings	4,647,312	2,887,892
Total Enstar Shareholders’ Equity	6,674,395	4,842,183
Noncontrolling interest	13,609	14,168
TOTAL SHAREHOLDERS’ EQUITY	6,688,004	4,856,351
TOTAL LIABILITIES, REDEEMABLE NONCONTROLLING INTEREST AND SHAREHOLDERS’ EQUITY	21,647,284	19,826,099
Voting ordinary shares
Ordinary shares (par value $1 each, issued and outstanding 2020: 22,085,232; 2019: 21,511,505):
Ordinary shares	18,576	18,002
Series C non-voting convertible ordinary shares
Ordinary shares (par value $1 each, issued and outstanding 2020: 22,085,232; 2019: 21,511,505):
Ordinary shares	2,600	2,600
Series E non-voting convertible ordinary shares
Ordinary shares (par value $1 each, issued and outstanding 2020: 22,085,232; 2019: 21,511,505):
Ordinary shares	910	910
Series C Preferred Shares
Preferred Shares:
Preferred shares	389	389
Series D Preferred Shares
Preferred Shares:
Preferred shares	400,000	400,000
Series E Preferred Shares
Preferred Shares:
Preferred shares	110,000	110,000
Short-term Investments
ASSETS
Fixed maturity investments, trading	5,129	51,490
Available-for-sale, at fair value	263,795	128,335
Fixed maturity investments, trading
ASSETS
Fixed maturity investments, trading	4,594,892	6,143,335
Available-for-sale, at fair value	$ 3,395,100	$ 1,538,052

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Allowance for estimated uncollectible reinsurance	$ 137,122	$ 147,639
Insurance balance recoverable, allowance for credit loss	4,824	3,818
Investments, available-for-sale, at fair value, amortized cost	3,576,641	1,666,126
Investments, allowance for credit losses	$ 322	$ 0
Ordinary shares, par value (dollars per share)	$ 1	$ 1
Ordinary shares, issued (shares)	22,085,232	21,511,505
Ordinary shares, outstanding (shares)	22,085,232	21,511,505
Treasury stock, preferred shares (shares)	388,571	388,571
Treasury stock, ordinary shares (shares)	565,630	0
Voting ordinary shares
Ordinary shares, par value (dollars per share)	$ 1	$ 1
Ordinary shares, issued (shares)	18,575,550	18,001,823
Ordinary shares, outstanding (shares)	18,575,550	18,001,823
Series C non-voting convertible ordinary shares
Ordinary shares, issued (shares)	2,599,672	2,599,672
Ordinary shares, outstanding (shares)	2,599,672	2,599,672
Series E non-voting convertible ordinary shares
Ordinary shares, issued (shares)	910,010	910,010
Ordinary shares, outstanding (shares)	910,010	910,010
Series C Preferred Shares
Preferred shares, issued (shares)	388,571	388,571
Treasury stock, preferred shares (shares)	388,571	388,571
Series D Preferred Shares
Preferred shares, issued (shares)	16,000	16,000
Preferred shares, outstanding (shares)	16,000	16,000
Series E Preferred Shares
Preferred shares, issued (shares)	4,400	4,400
Preferred shares, outstanding (shares)	4,400	4,400
Short-term Investments
Investments, available-for-sale, at fair value, amortized cost	$ 263,750	$ 128,311
Investments, allowance for credit losses	0
Fixed maturity investments, trading
Investments, available-for-sale, at fair value, amortized cost	3,312,891	$ 1,537,815
Investments, allowance for credit losses	$ 322

Consolidated Statements of Earn

Consolidated Statements of Earnings - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
INCOME
Net premiums earned	$ 572,092	$ 804,047	$ 695,779
Fees and commission income	42,446	28,453	35,088
Net investment income	302,817	308,271	261,698
Net realized and unrealized gains (losses)	1,642,019	1,011,966	(407,532)
Other income	101,132	37,070	34,073
Total income	$ 2,660,506	$ 2,189,807	$ 619,106
Revenue from Contract with Customer, Product and Service [Extensible List]	esgr:FeesAndCommissionsMember	esgr:FeesAndCommissionsMember	esgr:FeesAndCommissionsMember
EXPENSES
Net incurred losses and loss adjustment expenses	$ 415,926	$ 614,179	$ 323,722
Acquisition costs	171,020	240,609	177,855
General and administrative expenses	501,479	413,084	348,786
Interest expense	59,308	52,541	25,696
Net foreign exchange (gains) losses	16,393	(7,912)	2,644
Total expenses	1,164,126	1,312,501	878,703
EARNINGS (LOSS) BEFORE INCOME TAXES	1,496,380	877,306	(259,597)
Income tax benefit (expense)	(23,827)	(12,372)	3,689
Earnings from equity method investments	238,569	55,910	42,147
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	1,711,122	920,844	(213,761)
Net earnings from discontinued operations, net of income taxes	16,251	7,375	1,489
NET EARNINGS (LOSS)	1,727,373	928,219	(212,272)
Net loss attributable to noncontrolling interest	27,671	9,870	62,051
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	1,755,044	938,089	(150,221)
Dividends on preferred shares	(35,700)	(35,914)	(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$ 1,719,344	$ 902,175	$ (162,354)
Basic:
Net earnings (loss) from continuing operations (dollars per share)	$ 79.43	$ 41.80	$ (7.89)
Net earnings from discontinued operations (dollars per share)	0.35	0.20	0.05
Net earnings (loss) per ordinary share (dollars per share)	79.78	42	(7.84)
Diluted:
Net earnings (loss) from continuing operations (dollars per share)	78.45	41.23	(7.89)
Net earnings from discontinued operations (dollars per share)	0.35	0.20	0.05
Net earnings (loss) per ordinary share (dollars per share)	$ 78.80	$ 41.43	$ (7.84)
Weighted average ordinary shares outstanding:
Basic (shares)	21,551,408	21,482,617	20,698,310
Diluted (shares)	21,818,294	21,775,066	20,904,176

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
NET EARNINGS (LOSS)	$ 1,727,373	$ 928,219	$ (212,272)
Other comprehensive income (loss), net of income taxes:
Unrealized gains (losses) on fixed income available-for-sale investments arising during the year	104,924	2,896	(2,284)
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(509)	0	0
Reclassification adjustment for net realized (gains) losses included in net earnings	(18,033)	(3,894)	63
Reclassification to earnings on disposal of subsidiary	(11,856)	0	0
Unrealized gains (losses) arising during the year, net of reclassification adjustments	74,526	(998)	(2,221)
Change in currency translation adjustment	(2,103)	(2,428)	(202)
Reclassification to earnings on disposal of subsidiary	(34)	0	0
Cumulative currency translation adjustment, net of reclassification adjustments	(2,069)	(2,428)	(202)
Decrease in defined benefit pension liability	1,152	42	2,156
Total other comprehensive income (loss)	73,609	(3,384)	(267)
Comprehensive income (loss)	1,800,982	924,835	(212,539)
Comprehensive loss attributable to noncontrolling interest	27,550	9,985	62,291
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSTAR	$ 1,828,532	$ 934,820	$ (150,248)

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Treasury Shares (Series C Preferred Shares)	Joint Share Ownership Plan — Voting Ordinary Shares, Held in Trust	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Cumulative Currency Translation Adjustment	Defined benefit pension liability	Unrealized gains (losses) on available-for-sale investments	Retained Earnings	Retained EarningsCumulative effect of change in accounting principle	Noncontrolling Interest (excludes redeemable noncontrolling interests)	Voting ordinary sharesOrdinary Shares	Voting ordinary sharesAdditional Paid-in Capital	Series C non-voting convertible ordinary sharesOrdinary Shares	Series E non-voting convertible ordinary sharesOrdinary Shares	Series C non-voting preferred sharesPreferred Stock	Series D Preferred SharesPreferred Stock	Series E preferred perpetual sharesPreferred Stock
Balance, beginning of year at Dec. 31, 2017		$ (421,559)	$ 0	$ 1,395,067	$ 10,468	$ 11,171	$ (3,143)	$ 2,440	$ 2,132,912	$ (1,573)	$ 9,264	$ 16,402		$ 2,600	$ 405	$ 389	$ 0	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of shares			0									1,548	$ 413,141		505		400,000	110,000
Shares repurchased				0								0
Issuance costs of preferred shares				(14,643)
Amortization of share-based compensation				11,099
Other comprehensive income (loss)	$ (267)					(185)		(1,999)
Change in defined benefit pension liability	2,156						2,156
Net earnings (loss)	(162,354)								(212,272)
Net loss attributable to noncontrolling interest	62,051								62,051		2,743
Dividends on preferred shares									(12,133)
Change in redemption value of redeemable noncontrolling interests									7,554
Contribution (distribution) of noncontrolling interest											49
Balance, end of year at Dec. 31, 2018		(421,559)	0	1,804,664	10,440	10,986	(987)	441	1,976,539	0	12,056	17,950		2,600	910	389	400,000	110,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of shares			0									52	583		0		0	0
Shares repurchased				0								0
Issuance costs of preferred shares				0
Amortization of share-based compensation				31,531
Other comprehensive income (loss)	(3,384)					(2,438)		(873)
Change in defined benefit pension liability	42						42
Net earnings (loss)	902,175								928,219
Net loss attributable to noncontrolling interest	$ 9,870								9,870		2,159
Dividends on preferred shares									(35,914)
Change in redemption value of redeemable noncontrolling interests									9,178
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Contribution (distribution) of noncontrolling interest											(47)
Balance, end of year at Dec. 31, 2019	$ 4,856,351	(421,559)	0	1,836,778	7,171	8,548	(945)	(432)	2,887,892	$ (6,148)	14,168	18,002		2,600	910	389	400,000	110,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of shares			(566)									752			0		0	0
Shares repurchased				(25,828)								(178)	$ 815
Issuance costs of preferred shares				0
Amortization of share-based compensation				25,939
Other comprehensive income (loss)	73,609					(672)		73,008
Change in defined benefit pension liability	1,152						1,152
Net earnings (loss)	1,719,344								1,727,373
Net loss attributable to noncontrolling interest	27,671								27,671		(159)
Dividends on preferred shares									(35,700)
Change in redemption value of redeemable noncontrolling interests									46,224
Contribution (distribution) of noncontrolling interest											(400)
Balance, end of year at Dec. 31, 2020	$ 6,688,004	$ (421,559)	$ (566)	$ 1,836,074	$ 80,659	$ 7,876	$ 207	$ 72,576	$ 4,647,312		$ 13,609	$ 18,576		$ 2,600	$ 910	$ 389	$ 400,000	$ 110,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
OPERATING ACTIVITIES:
Net earnings (loss)	$ 1,727,373	$ 928,219	$ (212,272)
Net earnings from discontinued operations, net of income taxes	(16,251)	(7,375)	(1,489)
Adjustments to reconcile net earnings to cash flows provided by (used in) operating activities:
Realized losses (gains) on sale of investments	(178,851)	(86,071)	27,395
Unrealized losses (gains) on investments	(1,463,168)	(925,895)	380,137
Depreciation and other amortization	59,570	34,695	32,242
Earnings from equity method investments	(238,569)	(55,910)	(42,147)
Sales and maturities of trading securities	3,792,083	5,361,936	4,706,318
Purchases of trading securities	(2,139,399)	(4,405,433)	(5,343,965)
Other non-cash items	23,242	33,857	11,857
Changes in:
Reinsurance balances recoverable on paid and unpaid losses	52,027	(316,440)	(289,295)
Funds held by reinsured companies	(192,313)	(67,636)	(215,041)
Losses and loss adjustment expenses	1,002,520	821,049	897,091
Defendant asbestos and environmental liabilities	(141,356)	(18,142)	(15,844)
Insurance and reinsurance balances payable	86,645	50,859	133,676
Premiums receivable	23,326	204,358	(165,357)
Other operating assets and liabilities	389,487	(127,622)	(44,915)
Net cash flows provided by (used in) operating activities	2,786,366	1,424,449	(141,609)
INVESTING ACTIVITIES:
Acquisitions, net of cash acquired	0	172,482	(245,151)
Sales of subsidiaries, net of cash sold	(13,847)	0	0
Sales and maturities of available-for-sale securities	2,259,546	335,670	58,219
Purchase of available-for-sale securities	(4,180,893)	(1,826,724)	(10,385)
Purchase of other investments	(975,024)	(794,613)	(900,262)
Proceeds from other investments	594,676	581,639	434,255
Purchase of equity method investments	(33,000)	(69,213)	(155,440)
Sale of equity method investment	12,200	0	0
Other investing activities	906	(2,551)	(8,321)
Net cash flows used in investing activities	(2,335,436)	(1,603,310)	(827,085)
FINANCING ACTIVITIES:
Net proceeds from the issuance of preferred shares	0	0	495,357
Dividends on preferred shares	(35,700)	(35,914)	(12,133)
(Purchase) contribution by noncontrolling interest	0		49
(Purchase) contribution by noncontrolling interest		(47)
Contribution by redeemable noncontrolling interest	0	13,127	55,377
Contribution of capital to discontinued operations	0	(45,000)	(51,000)
Dividends paid to noncontrolling interest	(400)	(11,556)	(3,852)
Repurchase of shares	(26,006)	0	0
Receipt of loans	858,512	1,070,502	1,132,507
Repayment of loans	(679,000)	(742,574)	(914,319)
Net cash flows provided by financing activities	117,406	248,538	701,986
DISCONTINUED OPERATIONS CASH FLOWS:
Net cash flows provided by (used in) operating activities	107,644	339,067	(18,463)
Net cash flows (used in) provided by investing activities	(129,640)	(380,227)	1,331
Net cash flows provided by financing activities	0	45,000	51,000
Net cash flows from discontinued operations	(21,996)	3,840	33,868
EFFECT OF EXCHANGE RATE CHANGES ON FOREIGN CURRENCY CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(5,800)	(324)	2,588
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	540,540	73,193	(230,252)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF YEAR	971,349	901,996	1,166,116
NET CHANGE IN CASH OF BUSINESSES HELD-FOR-SALE	(138,773)	(3,840)	(33,868)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, END OF YEAR	1,373,116	971,349	901,996
Supplemental Cash Flow Information:
Income taxes paid, net of refunds	25,029	4,941	12,355
Interest paid	50,775	49,457	25,240
Reconciliation to Consolidated Balance Sheets:
Cash, cash equivalents and restricted cash	$ 971,349	$ 971,349	$ 1,166,116

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Nov. 30, 2020
Discontinued operations, disposed of by sale | StarStone US
Consideration received	$ 281,989	$ 235,000

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	1. DESCRIPTION OF BUSINESS Enstar Group Limited ("Enstar") is a Bermuda-based holding company, formed in 2001. Enstar is a leading global insurance group that offers innovative capital release solutions through its network of group companies in Bermuda, the United States, the United Kingdom, Continental Europe, Australia, and other international locations. Our ordinary shares are listed on the NASDAQ Global Select Market under the ticker symbol "ESGR". Unless the context indicates otherwise, the terms "Enstar," "we," "us" or "our" mean Enstar Group Limited and its consolidated subsidiaries and the term "Parent Company" means Enstar Group Limited and not any of its consolidated subsidiaries. Our business is organized into three segments: (i) Non-life Run-off: This segment comprises the operations of our subsidiaries that are in the business of running off property and casualty and other non-life (re)insurance business. It also includes our management business, which manages the run-off portfolios of third parties through our service companies; (ii) Atrium: Atrium Underwriters Ltd. is a managing general agent at Lloyd’s of London ("Lloyd's"), which manages Syndicate 609. Through our Lloyd’s corporate member, SGL No.1 Limited ("SGL No.1"), we provide 25% of the underwriting capacity for Atrium's Syndicate 609 (with the balance provided by traditional Lloyd’s Names). Atrium specializes in a wide range of industry classes, including marine, aviation and transit, property and casualty binding authorities, reinsurance, accident and health and non-marine direct and facultative. As of December 31, 2020, we have classified the Atrium segment as held-for-sale in view of the Exchange Transaction as discussed in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations."; and (iii) StarStone: StarStone was a global specialty insurer that offered a diverse range of property, casualty and specialty insurance through its operations in Bermuda, the United States, the United Kingdom, and Continental Europe. However, during 2020, StarStone's U.S. operations, including StarStone U.S. Holdings, Inc. and its subsidiaries ("StarStone U.S.") were sold and StarStone's remaining non-U.S. operations ("StarStone International") were placed into an orderly run-off. For further information, refer to Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations." Atrium and StarStone are reported as separate segments as of December 31, 2020 because they were managed and operated in separate and distinct manners. Atrium employees were not involved in the management or strategy of StarStone, nor were StarStone employees involved in the management or strategy of Atrium. Atrium and StarStone were monitored and reported upon separately and distinctly and the strategies and business plans were determined independently of each other. In addition, our other activities, which do not qualify as a reportable segment, include our corporate expenses, debt servicing costs, preferred share dividends, holding company income and expenses, foreign exchange and other miscellaneous items.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Significant Accounting Policies	2. SIGNIFICANT ACCOUNTING POLICIES Basis of Preparation The consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("U.S. GAAP"). The consolidated financial statements include our assets, liabilities and results of operations as of December 31, 2020 and 2019 and for the years ended December 31, 2020, 2019 and 2018. Results of operations for acquired subsidiaries are included from the date of acquisition. All significant intercompany transactions and balances have been eliminated. Certain prior period amounts have been reclassified to conform to the current period presentation as described in further detail in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations." These reclassifications had no impact on net earnings. Use of Estimates The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amount of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Our actual results may differ materially from these estimates. The impact of changes in estimates are reflected in earnings in the period during which the estimate is changed. Accounting policies that we believe are most dependent on assumptions and estimates are considered to be our critical accounting estimates and are related to the determination of: • liability for losses and loss adjustment expenses ("LAE"); • reinsurance balances recoverable on paid and unpaid losses; • defendant asbestos and environmental liabilities and related insurance balances recoverable; • valuation allowances on reinsurance balances recoverable and deferred tax assets; • impairment charges, including credit allowances on investment securities classified as available-for-sale ("AFS"), and impairments on deferred charge assets; • gross and net premiums written and net premiums earned; • fair value measurements of investments; • fair value estimates associated with accounting for acquisitions; • fair value estimates associated with loss portfolio transfer reinsurance agreements for which we have elected the fair value option; and • redeemable noncontrolling interests. We expect that uncertainty and volatility in financial markets relating to the COVID-19 pandemic will continue to impact the value of our investments. The scope, duration and magnitude of the direct and indirect effects of the COVID-19 pandemic are changing rapidly and are difficult to anticipate. As with others in our industry, we are subject to economic factors such as interest rates, foreign exchange rates, underwriting events, regulation, tax policy changes, political risks and other market risks that can impact our strategy, operations, and results. Significant Accounting Policies (a) Premiums Non-Life Non-life premiums written are earned on a pro-rata basis over the period the coverage is provided. Reinsurance premiums are recorded at the inception of the policy, are based upon contractual terms and, for certain business, are estimated based on underlying contracts or from information provided by insureds and/or brokers. Changes in reinsurance premium estimates are expected and may result in adjustments in future periods. Any subsequent differences arising on such estimates are recorded as premiums written in the period in which they are determined. Certain non-life contracts are retrospectively rated and provide for a final adjustment to the premium based on the final settlement of all losses. Premiums on such contracts are adjusted based upon contractual terms, and management judgment is involved with respect to the estimate of the amount of losses that we expect to incur. Additional premiums are recognized at the time loss thresholds specified in the contract are exceeded and are earned over the coverage period, or are earned immediately if the period of risk coverage has passed. Unearned Premium Reserves and Premiums Receivable Unearned premium reserves represent the unexpired portion of policy premiums. For retrospectively rated contracts as well as those contracts whose written premium amounts are recorded based on premium estimates at inception, changes to accrued premiums arising from changes to these estimates are reflected as changes in premium balances receivable where appropriate. Premium balances receivable are reported net of an allowance for expected credit losses as appropriate. The allowance is based upon our ongoing review of amounts outstanding, historical loss data, including delinquencies and write-offs, current and forecasted economic conditions and other relevant factors. However, the credit risk on our premiums receivable balances is substantially reduced where we have the ability to cancel the underlying policy if the policyholder does not pay the related premium. (b) Acquisition Costs Acquisition costs, consisting principally of commissions and brokerage expenses and certain premium taxes and fees incurred at the time a contract or policy is issued and that vary with and are directly related to the successful efforts of acquiring new insurance contracts or renewing existing insurance contracts, are deferred and amortized over the period in which the related premiums are earned. Deferred acquisition costs are limited to their estimated realizable value by line of business based on the related unearned premiums, anticipated claims and claim expenses and anticipated investment income. A premium deficiency occurs if the sum of anticipated losses and loss adjustment expenses exceed unearned premiums, deferred acquisition costs and anticipated investment income. A premium deficiency is initially recognized by charging any deferred acquisition costs to expense to the extent required in order to eliminate the deficiency. If the premium deficiency exceeds the deferred acquisition costs then a liability is accrued for the excess deficiency. (c) Losses and LAE Non-life Run-off The liability for losses and LAE in the Non-life Run-off segment includes an amount determined from reported claims and an amount, based on historical loss experience and industry statistics, for losses incurred but not reported ("IBNR") determined using a variety of actuarial methods. These estimates are continually reviewed and are necessarily subject to the impact of future changes in factors such as claim severity and frequency, changes in economic conditions including the impact of inflation, legal and judicial developments, and medical cost trends. Our estimates, at inception and on an ongoing basis, do not include an estimate for potential future commutations and policy buybacks. Commutations and policy buybacks are often unique and circumstance-based, and each commutation or policy buyback is separately negotiated. Therefore, the successful execution of one commutation or policy buyback does not necessarily impact the likelihood of other commutations or policy buybacks occurring in the future. While we believe that our liability for losses and LAE is adequate, the ultimate amount may be in excess of, or less than, the amounts recorded on our financial statements. Adjustments will be reflected as part of the net increase or reduction in losses and LAE liabilities in the periods in which they become known. Premium and commission adjustments may be triggered by changes in incurred losses, and any changes in such amounts are recorded in the same period that the related change in incurred loss is recognized. Commutations of acquired companies’ exposures have the effect of accelerating the payout of claims compared to the probability-weighted ranges of actuarially projected cash flows that we applied when estimating the fair values of assets and liabilities at the time of acquisition. Commutations and policy buybacks provide an opportunity for us to exit exposures to certain policies and insureds generally at a discount to our estimate of the ultimate liability and provide us with the ability to eliminate exposure to further losses. Commutations and policy buybacks can be beneficial to us as they legally extinguish liabilities in full, reduce the potential for future adverse loss development, and reduce future claims handling costs. Any material acceleration of payout together with the impact of any material loss reserve savings in any period will also accelerate the amortization of fair value adjustments and deferred charge assets and gain liabilities in that period. Commutations are only executed directly with insureds or reinsureds and any gains realized or losses incurred on the settlement of losses and LAE liabilities through commutations or policy buybacks are recognized upon the execution of a commutation or policy buyback with the insured or reinsured. Our (re)insurance subsidiaries also establish provisions for LAE relating to run-off costs for the estimated duration of the run-off, which are included in the liability for losses and LAE. These provisions are assessed at each reporting date, and provisions relating to future periods are adjusted to reflect any changes in estimates of the periodic run-off costs or the duration of the run-off, including the impact of any acceleration of the run-off period that may be caused by commutations. Provisions relating to the current period together with any adjustment to future run-off provisions are included in net incurred losses and LAE in the consolidated statements of earnings. Atrium and StarStone The reserves for losses and LAE in the Atrium and StarStone segments include reserves for unpaid reported losses and for IBNR loss reserves. The reserves for unpaid reported losses and loss expenses are established by management based on reports from brokers, ceding companies and insureds and represent the estimated ultimate cost of events or conditions that have been reported to or specifically identified by us. The reserve for IBNR losses is established by us based on actuarially determined estimates of ultimate losses and loss expenses. Inherent in the estimate of ultimate losses and loss expenses are expected trends in claim severity and frequency and other factors which may vary significantly as claims are settled. Accordingly, ultimate losses and loss expenses may differ from the amounts recorded in the consolidated financial statements. These estimates are reviewed regularly and, as experience develops and new information becomes known, the reserves are adjusted as necessary. Such adjustments, if any, will be recorded in earnings in the period in which they become known. Prior period development arises from changes to loss estimates recognized in the current year that relate to loss reserves established in previous calendar years. Components of Net Incurred Losses and LAE Included within the total net incurred losses and LAE on our consolidated statement of earnings are the following items: • Net losses paid: paid losses and LAE, net of related reinsurance recoveries. • Net change in case and LAE reserves: the change in case reserves and associated LAE, net of related reinsurance recoveries. • Net change in IBNR reserves: the change in IBNR reserves, net of related reinsurance recoveries. • Increase (reduction) in estimates of net ultimate losses: the total of net losses paid, net change in case and LAE reserves and the net change in IBNR. This includes the net impact of commutations and policy buybacks on the liability for losses and LAE reserves and reinsurance recoveries. • Increase (reduction) in provisions for unallocated LAE: the net change in our provision for unallocated LAE. • Amortization of deferred charge assets and deferred gain liabilities: relates to retroactive reinsurance contracts where, if at the inception of the contract, the estimated undiscounted ultimate losses payable are in excess of the premiums received, a deferred charge asset is recorded for the excess; whereas, if the premiums received are in excess of the estimated undiscounted ultimate losses payable, a deferred gain liability is recorded for the excess, such that we don't record any gain or loss at the inception of these retroactive reinsurance contracts. In addition, for retrocessions of losses and LAE reserves that we have assumed through retroactive reinsurance contracts where the retroceded liabilities exceed the retrocession premiums paid, we record the excess as a deferred gain liability which is amortized to earnings over the estimated period during which the losses paid on the assumed retroceded liabilities are recovered from the retrocessionaire. • Amortization of fair value adjustments: the amortization of the fair value adjustments associated with acquired companies, where the assumed losses and LAE reserves and the acquired reinsurance recoveries are fair valued on acquisition. • Changes in fair value - fair value option: the changes in the fair value for reinsurance agreements where we have elected the fair value option. The change in fair value component includes the changes in the discounted cash flows and risk margin. The underlying ("nominal") net losses paid, net change in case and LAE reserves and the net change in IBNR reserves relating to these reinsurance agreements for which we have elected the fair value option are included within the appropriate line items described above. • Net incurred losses and LAE: the total of the increase (reduction) in estimates of net ultimate losses, increase (reduction) in provisions for unallocated LAE, amortization of deferred charge assets and deferred gain liabilities, amortization of fair value adjustments and changes in fair value - fair value option. (d) Defendant Asbestos and Environmental Liabilities We acquired DCo LLC ("DCo") on December 30, 2016, and Morse TEC LLC ("Morse TEC") on October 30, 2019, as described in Note 3 - "Business Acquisitions." DCo and Morse TEC hold liabilities associated with personal injury asbestos claims and environmental claims arising from their legacy manufacturing operations. DCo and Morse TEC continue to process asbestos personal injury claims. Defendant asbestos and environmental liabilities on our consolidated balance sheets include amounts for indemnity and defense costs for pending and future claims, determined using standard actuarial techniques for asbestos-related exposures. Defendant asbestos and environmental liabilities also include amounts for environmental liabilities associated with DCo's and Morse TEC's properties. (e) Reinsurance Balances Recoverable on Paid and Unpaid Losses Amounts recoverable from reinsurers are estimated in a manner consistent with the underlying liability for losses and loss adjustment expenses. We report our reinsurance balances recoverable on paid and unpaid losses net of an allowance for estimated uncollectible amounts. The allowance is based upon our ongoing review of the outstanding balances and reflects factors such as the duration of the collection period, credit quality, changes in reinsurer credit standing, default rates specific to the individual reinsurer, the geographical location of the reinsurer, contractual disputes with reinsurers over individual contentious claims, contract language or coverage issues, industry analyst reports and consensus economic forecasts. A probability-of-default methodology that reflects current and forecasted economic conditions is used to estimate the allowance for uncollectible reinsurance due to credit-related factors. See "New Accounting Standards Adopted in 2020" below for the discussion on our adoption of the credit losses standard. The allowance also includes estimated uncollectible amounts related to dispute risk with reinsurers. Amounts deemed to be uncollectible, including amounts due from known insolvent reinsurers, are written off against the allowance. Changes in the allowance, as well as any subsequent collections of amounts previously written off, are reported as part of the net incurred losses and loss adjustment expenses in our consolidated statements of earnings. On an ongoing basis, we also evaluate and monitor the financial condition of our reinsurers under voluntary schemes of arrangement to minimize our exposure to significant losses from potential insolvencies. (f) Insurance Balances Recoverable Amounts billed to and due from insurers providing coverage for our defendant asbestos liabilities are calculated in accordance with the terms of the individual insurance contracts. The insurance balances recoverable related to our defendant asbestos liabilities are presented net of a provision for uncollectible amounts, reflecting the amount deemed not collectible primarily due to credit quality and contractual disputes with insurers over coverage issues. (g) Investments, Cash and Cash Equivalents Short-term investments and fixed maturity investments Short-term investments comprise investments with a maturity greater than three months up to one year from the date of purchase. Fixed maturities comprise investments with a maturity of greater than one year from the date of purchase. Short-term and fixed maturity investments classified as trading are carried at fair value, with realized and unrealized gains and losses included in net earnings and reported as net realized and unrealized gains and losses. Short-term and fixed maturity investments classified as AFS are carried at fair value, with unrealized gains and losses excluded from net earnings and reported as a separate component of accumulated other comprehensive income (loss) ("AOCI"). Realized gains and losses on sales of investments classified as AFS are recognized in the consolidated statements of earnings. The costs of short-term and fixed maturity investments are adjusted for amortization of premiums and accretion of discounts, recognized using the effective yield method and included in net investment income. For mortgage-backed and asset-backed investments, and any other holdings for which there is a prepayment risk, prepayment assumptions are evaluated and reviewed on a regular basis. Investment purchases and sales are recorded on a trade-date basis. Realized gains and losses on the sale of investments are based upon specific identification of the cost of investments. Allowance for Credit Losses We perform a detailed analysis every reporting period to identify any credit losses on our investment portfolios not measured at fair value through net earnings. Some of the factors that we consider when assessing whether an allowance for credit losses is required on our debt securities include: (1) the extent to which the fair value has been less than the amortized cost; (2) the financial condition, near-term and long-term prospects of the issuer, including the relevant industry conditions and trends, and implications of rating agency actions and offering prices; (3) the likelihood of the recoverability of principal and interest; and (4) whether it is more likely than not that we will be required to sell the security prior to an anticipated recovery in value. With effect from January 1, 2020, credit losses on our AFS debt securities are recognized through an allowance account which is deducted from the amortized cost basis of the security, with the net carrying value of the security presented on the consolidated balance sheet at the amount expected to be collected. To calculate the amount of the credit loss, we compare the present value of the expected future cash flows with the amortized cost basis of the AFS debt security, with the amount of the credit loss recognized being limited to the excess of the amortized cost basis over the fair value of the AFS debt security, effectively creating a “fair value floor”. See "New Accounting Standards Adopted in 2020" below for the discussion on our adoption of the credit losses standard. For our AFS debt securities that we do not intend to sell or for which it is more likely than not that we will not be required to sell before an anticipated recovery in value, we separate the credit loss component of any unrealized losses from the amount related to all other factors and report the credit loss component in net realized investment gains (losses) in our consolidated statements of earnings. The unrealized losses related to non-credit factors is reported in other comprehensive income. The allowance for credit losses account is adjusted for any additional credit losses, write-offs and subsequent recoveries and is reflected in earnings. For our AFS debt securities where we record a credit loss, a determination is made as to the cause of the credit loss and whether we expect a recovery in the fair value of the security. For our AFS debt securities where we expect a recovery in fair value, the constant effective yield method is utilized, and the investment is amortized to par. For our AFS debt securities that we intend to sell or for which it is more likely than not that we will be required to sell before an anticipated recovery in fair value, the full amount of the unrealized loss is included in net realized investment gains (losses). The new cost basis of the investment is the previous amortized cost basis less the credit loss recognized in net realized investment gains (losses). The new cost basis is not adjusted for any subsequent recoveries in fair value. We report the investment income accrued on our AFS debt securities within other assets and therefore separately from the underlying AFS debt securities. In addition, due to the short-term period during which accrued investment income remains unpaid, which is typically six months or less, since the coupon on our AFS debt securities is paid semi-annually or more frequently, we have elected not to establish an allowance for credit losses on our accrued investment income balances. Accrued investment income is written off through net realized investment gains (losses) at the time the issuer of the debt security defaults or is expected to default on payments. Uncollectible debt securities are written off when we determine that no additional payments of principal or interest will be received. Other-Than-Temporary Impairments ("OTTI") As discussed above and below, with effect from January 1, 2020, we adopted the new credit losses standard which replaced the OTTI model that was previously applicable to our AFS debt securities. The new approach now requires the recognition of impairment charges relating to credit losses through an allowance account and limits the amount of credit loss to the difference between a security’s amortized cost basis and its fair value. A description of our historical OTTI process which was in place prior to our adoption of the new credit losses standard and which applied to our comparative financial statements is provided below. Fixed maturity investments classified as AFS were reviewed quarterly to determine if they had sustained an impairment of value that was, based on our judgment, considered to be other than temporary. The process included reviewing each fixed maturity investment whose fair value was below amortized cost and: (1) determining if we had the intent to sell the fixed maturity investment; (2) determining if it was more likely than not that we would be required to sell the fixed maturity investment before its anticipated recovery; and (3) assessing whether a credit loss existed, that is, whether we anticipated if the present value of the cash flows expected to be collected from the fixed maturity investment would be less than the amortized cost basis of the investment. In assessing whether it was more likely than not that we would be required to sell a fixed maturity investment before its anticipated recovery, we considered various factors including our future cash flow requirements, legal and regulatory requirements, the level of our cash, cash equivalents, short-term investments and fixed maturity investments available-for-sale in an unrealized gain position, and other relevant factors. In evaluating credit losses, we considered a variety of factors in the assessment of a fixed maturity investment including: (1) the time period during which there had been a significant decline below cost; (2) the extent of the decline below cost and par; (3) the potential for the investment to recover in value; (4) an analysis of the financial condition of the issuer; (5) the rating of the issuer; and (6) failure of the issuer of the investment to make scheduled interest or principal payments. If we concluded that an investment was other-than-temporarily impaired, then the difference between the fair value and the amortized cost of the investment was presented as an OTTI charge in the consolidated statements of earnings, with an offset for any non-credit related loss component of the OTTI charge recognized in other comprehensive income. Accordingly, only the credit loss component of the OTTI amount would have an impact on our earnings. Equities We hold investments in publicly traded equities and exchange-traded funds as well as in privately held equities. Our equity investments are carried at fair value with realized and unrealized gains and losses included in net earnings and reported as net realized and unrealized gains and losses. Other investments, at fair value Other investments include investments in limited partnerships and limited liability companies (collectively "private equities") and fixed income funds, hedge funds, equity funds, private credit funds and collateralized loan obligation ("CLO") equity funds that carry their investments at fair value, as well as direct investments in CLO equities. These other investments are stated at fair value, which ordinarily will be the most recently reported net asset value as advised by the fund manager or administrator. Many of our fund investments publish net asset values on a daily basis and provide daily liquidity while others report on a monthly or quarterly basis. The change in fair value is included in net realized and unrealized gains and losses on investments and recognized in net earnings. Equity method investments Investments in which the Company has significant influence over the operating and financial policies of the investee are classified as equity method investments and are accounted for using the equity method of accounting. In applying the equity method of accounting, investments are initially recorded at cost and are subsequently adjusted based on the Company's proportionate share of net income or loss of the investee, net of any distributions received from the investee. We typically record our proportionate share of an investee's net income or loss on a quarter lag in line with the timing of when they report their financial information to us. Any adjustments made to the carrying value of our equity method investees are based on the most recently available financial information from the investees. Changes in the carrying value of such investments are recorded in our consolidated statements of earnings as earnings (losses) from equity method investments. Any decline in the value of our equity method investments considered by management to be other-than-temporary is reflected in our consolidated statements of earnings in the period in which it is determined. Cash and cash equivalents Cash equivalents includes money market funds, fixed interest deposits and all highly liquid debt instruments purchased with an original maturity of three months or less. (h) Variable interest entities We have investments in certain limited partnership funds which are deemed to be variable interest entities (“VIEs”) and which are included in other investments at the reported net asset value (“NAV”). Determining whether to consolidate a VIE may require judgment in assessing (i) whether an entity is a VIE, and (ii) if we are the entity’s primary beneficiary and thus required to consolidate the entity. To determine if we are the primary beneficiary of a VIE, we evaluate whether we have (i) the power to direct the activities that most significantly impact the VIE’s economic performance, and (ii) the obligation to absorb losses or the right to receive benefits of the VIE that could potentially be significant to the VIE. Our evaluation includes identification of the activities that most significantly impact the VIE’s economic performance and an assessment of our ability to direct those activities based on governance provisions, contractual arrangements to provide or receive certain services, funding commitments and other applicable agreements and circumstances. Our assessment of whether we are the primary beneficiary of our VIEs requires significant assumptions and judgment. (i) Funds Held Under funds held arrangements, the reinsured company has retained funds that would otherwise have been remitted to our reinsurance subsidiaries. The funds balance is credited with investment income and losses payable are deducted. Funds held are shown under two categories on the consolidated balance sheets, funds held where we receive the underlying portfolio economics are shown as "Funds held - directly managed", and funds held where we receive a fixed crediting rate are shown as "Funds held by reinsured companies". Funds held by reinsured companies are carried at cost. Funds held - directly managed, are carried at fair value and represents the aggregate of funds held at cost and the value of an embedded derivative. The embedded derivative relates to our contractual right to receive the return on the underlying investment portfolio economics. The investment returns on both categories of funds held are recognized in net investment income and net realized and unrealized gains (losses). The revaluation of the embedded derivative is included in net unrealized gains (losses). (j) Fees and Commission Income Fees and commission income primarily includes profit commissions earned from managed Lloyd's syndicates as well as fees earned under fronting and consulting arrangements with third-party clients, which are recorded on an accrual basis. (k) Foreign Exchange Our reporting currency is the U.S. dollar. Assets and liabilities of certain of our subsidiaries and equity method investees whose functional currency is not the U.S. dollar are translated at period end exchange rates. Revenues and expenses of such foreign entities are translated at average exchange rates during the year. The effect of the currency translation adjustments for these foreign entities is included in accumulated other comprehensive income (loss). Other foreign currency assets and liabilities that are considered monetary items are translated at exchange rates in effect at the balance sheet date. Foreign currency revenues and expenses are translated either at transaction date exchange rates or using an appropriately weighted average exchange rate for the reporting period. These exchange gains and losses are recognized in net earnings. (l) Share-based Compensation We primarily use four types of share-based compensation arrangements: (i) restricted shares, restricted share units and performance share units ("PSUs"), (ii) joint share ownership program ("JSOP"), (iii) cash-settled stock appreciation rights ("SARs") and (iv) shares issued under our employee share purchase plans. With the exception of SARs and the incentive plan awards issued to certain employees of Atrium and StarStone, our share-based compensation awards qualify for equity classification. For equity-classified awards, the fair value of the compensation cost is measured at the grant date and is expensed over the service period of the award within general and administrative expenses in the consolidated statements of earnings except for PSUs where the expense also varies depending on the performance multiplier on the award. The SARs, the Atrium and StarStone incentive plan awards are classified as liability awards. Liability classified awards are recorded at fair value within other liabilities in the consolidated balance sheet with changes in fair value relating to the vested portion of the award recorded within general and administrative expenses in the consolidated statements of earnings. (m) Derivative Instruments We utilize derivative instruments in our foreign currency, investments and interest rate risk management strategies and recognize all derivatives as either assets or liabilities in the consolidated balance sheets and carry them at the fair value of the specific instrument utilized. Changes in the fair value as well as realized gains or losses on derivative instruments are

Business Acquisitions

Business Acquisitions	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Business Acquisitions	3. BUSINESS ACQUISITIONS2019 Morse TEC Overvie w On October 30, 2019, we completed the acquisition of Morse TEC LLC ("Morse TEC") through our subsidiary, Enstar Holdings (US) LLC for $0 purchase price. Morse TEC held $0.7 billion in liabilities associated with personal injury asbestos claims and environmental claims arising from BorgWarner's legacy manufacturing operations. We applied the acquisition method to account for the Morse TEC transaction as required by ASC 805 - Business Combinations , with no goodwill or gain from bargain purchase being recorded on the acquisition. In addition, no intangible assets were identified for recognition on the acquisition. Fair Value of Net Assets Acquired and Liabilities Assumed The following table summarizes the fair values of the assets acquired and liabilities assumed in the Morse TEC transaction at the acquisition date, which were allocated to the Non-life Run-off segment. ASSETS Cash and cash equivalents $ 171,412 Deferred tax assets 140,000 Other assets - insurance balances receivable 371,116 TOTAL ASSETS 682,528 LIABILITIES Defendant asbestos and environmental liabilities 662,507 Other liabilities 20,021 TOTAL LIABILITIES $ 682,528 NET ASSETS ACQUIRED AT FAIR VALUE — Morse TEC's Results Included in the Consolidated Statement of Earnings The table below summarizes the results of the Morse TEC operations, which were included in our consolidated statement of earnings from the acquisition date to December 31, 2019: Net investment income $ 488 General and administrative expenses (1,459) Other expenses (1,512) Net loss $ (2,483) Maiden Re North America Overvie w On December 27, 2018, we completed the acquisition of Maiden Reinsurance North America, Inc. (“Maiden Re North America”) from a subsidiary of Maiden Holdings, Ltd. ("Maiden Holdings"). Maiden Re North America is an insurance company domiciled in Missouri that provides property and casualty treaty reinsurance, casualty facultative reinsurance and accident and health treaty reinsurance. As part of the transaction, we also novated and assumed certain reinsurance agreements from Maiden Holdings' Bermuda reinsurer, including certain reinsurance agreements with Maiden Re North America. Refer to Note 4 - "Significant New Business" for additional information relating to these reinsurance agreements. We have operated the business in run-off since we acquired it. Purchase Price The total cash paid in the transaction was $286.4 million, subject to certain post-closing adjustments. The components of the consideration paid to acquire all of the outstanding shares of Maiden Re North America were as follows: Cash paid $ 286,375 Adjustment for the fair value of preexisting relationships 10,273 Total purchase price $ 296,648 Net assets acquired at fair value (including preexisting relationships) $ 296,648 Excess of purchase price over fair value of net assets acquired $ — The purchase price was allocated to the acquired assets and liabilities of Maiden Re North America based on their estimated fair values at the acquisition date. Adjustment for the Fair Value of Preexisting Relationships Enstar had contractual preexisting relationships with Maiden Re North America, 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 Maiden Re North America were deemed to equal their carrying values given their short-term nature and the expectation that they would all be settled within twelve months following acquisition. 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 and net of the intercompany cession assumed as part of the transaction) in the Maiden Re North America transaction at the acquisition date, which have all been allocated to the Non-life Run-off segment. ASSETS Fixed maturities, trading, at fair value $ 1,098,593 Short-term investments, trading, at fair value 3,508 Total investments 1,102,101 Cash and cash equivalents 12,035 Restricted cash and cash equivalents 26,871 Premiums receivable 138,378 Prepaid reinsurance premiums 3,257 Reinsurance balances recoverable 87,018 Other assets 96,669 TOTAL ASSETS $ 1,466,329 LIABILITIES Losses and LAE $ 1,027,367 Unearned premiums 85,696 Other liabilities 56,618 TOTAL LIABILITIES 1,169,681 NET ASSETS ACQUIRED AT FAIR VALUE $ 296,648 Maiden Re North America's Results Included in the Consolidated Statement of Earnings The table below summarizes the results of the Maiden Re North America operations, which were included in our consolidated statement of earnings from the acquisition date to December 31, 2018: Net investment income $ 675 Net unrealized gains 3,749 General and administrative expenses (435) Net earnings $ 3,989 KaylaRe Overvie w On May 14, 2018, the Company acquired 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. Effective September 30, 2019, KaylaRe and KaylaRe Ltd. merged with Cavello Bay Reinsurance Limited, a wholly-owned subsidiary of the Company, with Cavello Bay Reinsurance Limited as the surviving company. Refer to Note 21 - "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 Enstar's voting ordinary shares of $206.65 as of May 14, 2018, the date the transaction closed. Enstar's non-voting ordinary shares are economically equivalent to Enstar's voting ordinary shares. Number of Enstar ordinary shares issued 2,007,017 Closing price of Enstar voting ordinary shares as of May 14, 2018 $ 206.65 Fair value of Enstar ordinary shares issued to shareholders of KaylaRe $ 414,750 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 earnings (losses) from equity method investments 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 KaylaRe's Results Included in the Consolidated Statement of Earnings The table below summarizes the results of the KaylaRe operations, which are included in our consolidated statement of earnings from the acquisition date to December 31, 2018: Premiums earned $ 13,627 Incurred losses and LAE (12,364) Acquisition costs (341) Underwriting income 922 Net investment income 3,096 Net unrealized gains (47,769) General and administrative expenses (2,164) Net loss $ (45,915)

Significant New Business

Significant New Business	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Significant New Business	4. SIGNIFICANT NEW BUSINESS We define significant new business as material transactions other than business acquisitions which are included in Note 3 - "Business Acquisitions." Generally, our significant new business takes the form of reinsurance or direct business transfers. The table below sets forth a summary of significant new business that we have completed between January 1, 2018 and December 31, 2020: Transaction Date Completed Total Assets Assumed Deferred Charge Asset (1) Total Liabilities Assumed Net Fair Value Adjustment (2) Primary Nature of Business Hannover Re August 6, 2020 $ 182,498 N/A $ 209,713 $ (27,215) U.S. asbestos, environmental and workers' compensation liabilities Munich Re July 1, 2020 $ 100,956 N/A $ 100,956 N/A Australian public liability, professional liability and builders' warranty liabilities AXA Group (3) June 1, 2020 $ 179,681 N/A $ 179,681 N/A U.S. construction general liability Aspen June 1, 2020 $ 770,000 $ 11,746 $ 781,746 N/A Diversified mix of property, liability and specialty lines of business across the U.S., U.K. and Europe Lyft March 31, 2020 $ 465,000 N/A $ 465,000 N/A U.S. motor Zurich (3) October 1, 2019 $ 507,061 $ 115,815 $ 622,876 N/A U.S. asbestos and environmental liability Maiden Re Bermuda August 5, 2019 $ 445,000 $ 85,183 $ 530,183 N/A U.S. workers' compensation and General Casualty Amerisure April 11, 2019 $ 45,463 $ 2,873 $ 48,336 N/A U.S. construction defect AmTrust February 14, 2019 $ 1,143,949 $ 20,633 $ 1,164,582 N/A Lloyd's property, professional, marine, non-marine, affinity annual, extended warranty and political Allianz SE December 31, 2018 $ 70,000 N/A $ 70,000 N/A Asbestos and environmental Maiden Re Bermuda December 27, 2018 $ 70,425 $ 1,704 $ 72,129 N/A U.S. workers' compensation and motor Coca-Cola August 1, 2018 $ 103,617 $ 17,208 $ 120,825 N/A U.S. workers' compensation, auto liability, general and product liability Zurich Australia February 23, 2018 $ 268,657 N/A $ 280,764 $ (12,107) Australian motor Neon February 16, 2018 $ 525,673 N/A $ 546,298 $ (20,625) Medical malpractice, general liability, professional indemnity and marine Novae January 29, 2018 $ 1,095,730 N/A $ 1,163,198 $ (67,468) Financial, casualty, marine and energy, professional indemnity, aviation, motor and property The table below sets forth a summary of significant new business that we have signed or completed between January 1, 2021 and March 1, 2021: Transaction Date Completed Initial Estimate of Liabilities Assumed Primary Nature of Business AXA Group (4) N/A - Announced February 25, 2021 $ 1,395,000 Diversified mix of global casualty and professional lines ProSight (4) N/A - Announced January 15, 2021 $ 500,000 U.S. discontinued workers' compensation and excess workers' compensation lines of business and adverse development cover on a diversified mix of general liability classes of business CNA (4) February 5, 2021 $ 690,000 U.S. excess workers' compensation Liberty Mutual (4) January 8, 2021 $ 420,000 U.S. energy liability, construction liability and homebuilders liability (1) Where the estimated ultimate losses payable exceed the premium consideration received at the inception of the agreement, a deferred charge asset is recorded. (2) When the fair value option is elected for any retroactive reinsurance agreement, an initial net fair value adjustment is recorded at the inception of the agreement. (3) Effective October 1, 2020 and 2019, we ceded 10% of the AXA Group and Zurich transactions, respectively, to Enhanzed Reinsurance Ltd. ("Enhanzed Re"), in which we have an investment, on the same terms and conditions as those received by us. (4) The retroactive reinsurance agreements with AXA Group, ProSight, CNA and Liberty Mutual either closed or are expected to close in 2021 and therefore the related balances are not included in our consolidated financial statements as of December 31, 2020.

Divestitures, Held-For-Sale Bus

Divestitures, Held-For-Sale Businesses and Discontinued Operations	12 Months Ended
	Dec. 31, 2020
Discontinued Operations and Disposal Groups [Abstract]
Divestitures, Held-For-Sale Business and Discontinued Operations	5. DIVESTITURES, HELD-FOR-SALE BUSINESSES AND DISCONTINUED OPERATIONS Atrium Exchange Transaction On August 13, 2020, we announced an exchange transaction with Trident V, L.P., Trident V Parallel Fund, L.P. and Trident V Professionals Fund, L.P. (collectively, the "Trident V Funds") managed by Stone Point Capital LLC ("Stone Point"). As part of the exchange, we entered into a recapitalization agreement with the Trident V Funds, Dowling Capital Partners I, L.P. and Capital City Partners LLC (collectively, the "Dowling Funds"), North Bay Holdings Limited ("North Bay"), and StarStone Specialty Holdings Limited ("SSHL"). On January 1, 2021, this transaction was completed. As of December 31, 2020, Enstar owned an indirect 59.0% interest in North Bay and the Trident V Funds and the Dowling Funds owned 39.3% and 1.7%, respectively. North Bay owns 100.0% of SSHL, the holding company for the StarStone group, which previously included StarStone U.S. and still includes StarStone International. North Bay also owned 92.1% of Northshore Holdings Limited ("Northshore"), the holding company that owns Atrium Underwriting Group Limited and its subsidiaries (collectively, "Atrium") and Arden Reinsurance Company Ltd. ("Arden"). The remaining share ownership of Northshore is held on behalf of certain Atrium employees. Pursuant to the terms of the recapitalization agreement, we exchanged a portion of our indirect interest in Northshore for all of the Trident V Funds’ indirect interest in StarStone U.S., which was owned through an interest in Core Specialty (the “Exchange Transaction”). Effective January 1, 2021, we own 25.23% of Core Specialty on a fully diluted basis, which in turn owns StarStone U.S., and 13.8% of Northshore, which continues to own Atrium and Arden. Furthermore, the Trident V Funds no longer own any interest in Core Specialty but own 76.3% of Northshore, while the Dowling Funds own 0.4% of Core Specialty and 1.6% of Northshore. The Exchange Transaction had no impact on the ultimate ownership of SSHL, which continues to own StarStone International, with us, the Trident V Funds and the Dowling Funds retaining our and their current ownership interests in SSHL of 59.0%, 39.3% and 1.7%, respectively. Effective January 1, 2021, Northshore was deconsolidated and our remaining investment will be accounted for as a privately held equity investment and carried at its fair value. Through our wholly-owned subsidiary SGL No.1, a Lloyd’s corporate member included within our Non-life Run-off segment, we provided 25% of the underwriting capacity on the 2017 to 2020 underwriting years of Atrium's Syndicate 609 at Lloyd’s. Effective January 1, 2021, and in conjunction with the completion of the Atrium Exchange Transaction, SGL No.1 ceased its provision of underwriting capacity on Syndicate 609. Accordingly, the 2020 underwriting year was the last underwriting year that SGL No. 1 participated in with respect to the Atrium business. We will continue to report SGL No. 1's 25% gross-up share of the 2020 and prior underwriting years of Syndicate 609 until the 2020 underwriting year completes an RITC into a successor year, which will be no earlier than December 31, 2022. There is no net retention for Enstar on Atrium's 2020 and prior underwriting years as the business was contractually transferred to the Atrium entities that were divested in the Exchange Transaction. Effective January 1, 2021, certain balances that SGL No. 1 has with Atrium and Arden will no longer be eliminated on consolidation. As of December 31, 2020, we have classified the assets and liabilities of Northshore as held-for-sale but it did not qualify as a discontinued operation since the pending disposal did not represent a strategic shift that would have a major effect on our operations and financial results. The following table summarizes the components of Northshore's assets and liabilities held-for-sale on our consolidated balance sheet as of December 31, 2020: December 31, 2020 ASSETS Short-term investments, AFS, at fair value $ 1,720 Fixed maturities, trading, at fair value 154,026 Fixed maturities, AFS, at fair value 7,483 Other investments, at fair value 9,897 Total investments 173,126 Cash and cash equivalents 71,156 Restricted cash and cash equivalents 152,044 Premiums receivable 62,392 Reinsurance balances recoverable on paid and unpaid losses 37,341 Funds held by reinsured companies 32,226 Other assets 182,993 TOTAL ASSETS HELD-FOR-SALE $ 711,278 LIABILITIES Losses and loss adjustment expenses $ 254,149 Insurance and reinsurance balances payable 12,393 Debt obligations 39,850 Other liabilities 177,265 TOTAL LIABILITIES HELD-FOR-SALE $ 483,657 NET ASSETS HELD-FOR-SALE $ 227,621 As of December 31, 2020, included in the table above were restricted investments of $94.4 million. Recapitalization of StarStone U.S. and Discontinued Operations On November 30, 2020, we completed the sale and recapitalization of StarStone U.S. through the sale of StarStone U.S. to Core Specialty, a newly formed entity with equity backing from funds managed by SkyKnight Capital, L.P., Dragoneer Investment Group and Aquiline Capital Partners LLC. We received consideration of $282.0 million inclusive of $235.0 million of common shares of Core Specialty and cash of $47.0 million. The $235.0 million of common shares of Core Specialty represents a 25.23% interest in Core Specialty on a fully diluted basis. Our investment in Core Specialty is accounted for as an equity method investment and we record our proportionate share of the net earnings on a one quarter lag. StarStone U.S. comprised a substantial portion of the StarStone segment. We classified the assets and liabilities of StarStone U.S. as held-for-sale. The following table summarizes the components of StarStone U.S.'s assets and liabilities held-for-sale on our consolidated balance sheet as of December 31, 2019: December 31, 2019 (1) ASSETS Fixed maturities, trading, at fair value $ 202,994 Fixed maturities, AFS, at fair value 375,337 Equities, at fair value 3,000 Other investments, at fair value 6,389 Total investments 587,720 Cash and cash equivalents 78,613 Restricted cash and cash equivalents 5,815 Premiums receivable 99,367 Deferred tax assets 15,191 Reinsurance balances recoverable on paid and unpaid losses 530,604 Funds held by reinsured companies 35,861 Deferred acquisition costs 36,992 Goodwill and intangible assets 24,900 Other assets 59,707 TOTAL ASSETS HELD-FOR-SALE $ 1,474,770 LIABILITIES Losses and loss adjustment expenses $ 836,761 Unearned premiums 218,166 Insurance and reinsurance balances payable 22,453 Other liabilities 131,151 TOTAL LIABILITIES HELD-FOR-SALE $ 1,208,531 NET ASSETS HELD-FOR-SALE $ 266,239 (1) Following our decision to sell StarStone U.S. to Core Specialty which was completed on November 30, 2020, the assets and liabilities of StarStone U.S. as of December 31, 2019 were reclassified to held-for-sale on our consolidated balance sheets, in addition to the comparatives being restated since StarStone U.S. qualified as a discontinued operation. As of December 31, 2019, included in the table above were restricted investments of $131.0 million. The StarStone U.S. business qualified as a discontinued operation. The following table summarizes the components of net earnings (loss) from discontinued operations, net of income taxes, related to StarStone U.S., on the consolidated statements of earnings for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 INCOME Net premiums earned $ 291,326 $ 350,814 $ 199,796 Net investment income 12,849 15,606 10,572 Net realized and unrealized gains 5,431 19,385 (5,352) Other income 49 9 10 309,655 385,814 205,026 EXPENSES Net incurred losses and loss adjustment expenses 191,844 258,396 130,303 Acquisition costs 57,640 65,342 14,935 General and administrative expenses 60,236 60,003 58,590 Interest expense 2,066 2,600 2,120 Net foreign exchange (gains) losses (13) 33 24 311,773 386,374 205,972 EARNINGS (LOSS) BEFORE INCOME TAXES (2,118) (560) (946) Income tax benefit 2,255 7,935 2,435 NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES, BEFORE GAIN ON SALE $ 137 $ 7,375 $ 1,489 DISPOSAL Consideration received $ 281,989 $ — $ — Less: Carrying value of subsidiary (277,697) — — Add: Net realized gains on AFS securities and cumulative currency translation adjustments previously recognized in AOCI 11,822 — — Gain on sale of subsidiary $ 16,114 $ — $ — NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES $ 16,251 $ 7,375 $ 1,489 Net loss (earnings) from discontinued operations attributable to noncontrolling interest (8,717) (3,025) (611) NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS $ 7,534 $ 4,350 $ 878 Continuing Involvement Disclosures Following the completion of the sale of StarStone U.S. to Core Specialty on November 30, 2020, our continuing involvement with StarStone U.S comprised of the following transactions: LPT and ADC reinsurance agreement In connection with the sale of StarStone U.S. to Core Specialty, one of our Non-life Run-off subsidiaries entered into an LPT and ADC reinsurance agreement with StarStone U.S. pursuant to which we reinsured all of the net loss reserves of StarStone U.S. in respect of premium earned prior to October 31, 2020. Under the terms of the LPT and ADC reinsurance agreement, we assumed total net loss reserves of $462.4 million from StarStone U.S. in exchange for a total reinsurance premium consideration of $478.2 million, subject to an aggregate limit of $130.0 million above the assumed total net loss reserves. Our Non-life Run-off subsidiary's obligations to StarStone U.S. under the LPT and ADC reinsurance agreement are guaranteed by us. The LPT and ADC reinsurance agreement between us and StarStone U.S. shall continue in force until such time as our liability with respect to the assumed total net loss reserves terminates. Concurrent with the closing of the LPT and ADC reinsurance agreement, one of our wholly-owned subsidiaries entered into an Administrative Services Agreement ("ASA") with StarStone U.S., through which it was appointed as an independent contractor to provide certain administrative services covering the business we assumed from StarStone U.S. through the LPT and ADC reinsurance agreement. This ASA became effective on November 30, 2020 and shall continue until its termination. In addition, concurrent with the sale of StarStone U.S. to Core Specialty which was completed on November 30, 2020, one of our wholly-owned subsidiaries entered into a Transition Services Agreement ("TSA") with Core Specialty through which our subsidiary and Core Specialty agreed to provide certain transitional services to each other relating to the StarStone U.S. businesses, for a specified period of time. This TSA became effective on November 30, 2020 and unless otherwise agreed to in writing by both Core Specialty and us, shall terminate on the earliest to occur of (a) the 2-year anniversary of the agreement, (b) the date on which all the covered transitional services have been terminated, and (c) the termination of the agreement. Reinsurance transactions previously eliminated on consolidation The table below presents a summary of the total income and expenses which have been recognized within our continuing operations for the years ended December 31, 2020, 2019 and 2018, relating to intercompany transactions, primarily intra-group reinsurances, between StarStone U.S. and our subsidiaries: 2020 2019 2018 Total Income $ 11,911 $ 10,672 $ 98,402 Total Expenses (1) (16,397) 62,515 113,952 Net Earnings (Loss) $ 28,308 $ (51,843) $ (15,550) (1) For the year ended December 31, 2020, negative total expenses were driven by favorable loss development on the losses and LAE reserves ceded by StarStone U.S. to our subsidiaries. Cash flows The cash inflows (outflows) between our subsidiaries and StarStone U.S. for the years ended December 31, 2020, 2019 and 2018 were $99.2 million, $(53.9) million and $(64.6) million, respectively. Equity method investment We have applied the equity method of accounting to the common shares we acquired in Core Specialty as part-consideration for the sale of StarStone U.S. and which make up 25.23% of the total outstanding common shares in Core Specialty on a fully diluted basis. Since we account for our share of earnings attributable to our equity method investees on a quarter lag, the carrying value of our investment in the common shares of Core Specialty as at December 31, 2020 remained unchanged from our November 30, 2020 fair value of $235.0 million, when we completed the sale of StarStone U.S. to Core Specialty. Run-off of StarStone International (non-U.S.) On June 10, 2020, we announced that we placed StarStone International into an orderly run-off (the "StarStone International Run-Off"). The liabilities associated with the StarStone International Run-Off vary in duration, and the run-off is expected to occur over a number of years. Steps to reduce the size of StarStone International's operations have begun and will involve several phases that will occur over time. As a result, we cannot anticipate with certainty the expected completion date of the StarStone International Run-Off. We continue to evaluate additional strategic options for StarStone International's operations and business. Consequently, such options could have the effect of mitigating costs associated with placing the business into run-off. The remaining StarStone International operations will continue to serve the needs of policyholders and ensure that the companies continue to meet all regulatory requirements. The results of StarStone International are included within continuing operations in the StarStone segment. Recent developments relating to StarStone International include: • On October 2, 2020, StarStone International sold the renewal rights for its financial lines portfolio for consideration of $0.5 million. • On October 14, 2020, we completed the sale of Vander Haeghen & Co. SA ("VdH"), a Belgium-based insurance agency majority owned by StarStone International entities, for consideration of €3.8 million ($4.5 million). We recognized a gain on the sale of $3.4 million in the fourth quarter of 2020. • On November 17, 2020, we announced an agreement to sell StarStone Underwriting Limited ("SUL"), the Lloyd's managing agency, together with the right to operate Lloyd's Syndicate 1301, to Inigo Limited ("Inigo"). We currently have a 59.0% interest in SUL and the Trident V Funds and the Dowling Funds

Investments

Investments	12 Months Ended
	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
INVESTMENTS	6. INVESTMENTS We hold: (i) trading portfolios of short-term and fixed maturity investments and equities, carried at fair value; (ii) AFS portfolios of short-term and fixed maturity investments, carried at fair value; (iii) other investments carried at fair value; (iv) equity method investments; and (v) funds held - directly managed. Asset Types The fair values of the underlying asset categories comprising our short-term and fixed maturity investments classified as trading and AFS and the fixed maturity investments included within our funds held - directly managed balance were as follows as of December 31, 2020 and 2019: 2020 Short-term investments, trading Short-term investments, AFS Fixed maturities, trading Fixed maturities, AFS Fixed maturities, funds held - directly managed Total U.S. government and agency $ — $ 243,556 $ 123,874 $ 474,442 $ 109,176 $ 951,048 U.K. government — — 37,508 13,574 — 51,082 Other government 3,424 3,213 327,437 146,914 21,165 502,153 Corporate 1,705 17,026 3,227,726 1,920,323 519,952 5,686,732 Municipal — — 79,959 30,032 52,678 162,669 Residential mortgage-backed — — 154,471 328,871 70,603 553,945 Commercial mortgage-backed — — 347,225 276,488 230,377 854,090 Asset-backed — — 296,692 204,456 56,312 557,460 Total fixed maturity and short-term investments $ 5,129 $ 263,795 $ 4,594,892 $ 3,395,100 $ 1,060,263 $ 9,319,179 2019 Short-term investments, trading Short-term investments, AFS Fixed maturities, trading Fixed maturities, AFS Fixed maturities, funds held - directly managed Total U.S. government and agency $ — $ 111,583 $ 208,296 $ 269,661 $ 106,537 $ 696,077 U.K. government 24,411 1,069 122,012 14,280 — 161,772 Other government 21,958 387 575,017 84,760 20,734 702,856 Corporate 5,121 13,915 3,959,288 866,557 603,389 5,448,270 Municipal — 1,381 87,451 2,399 49,456 140,687 Residential mortgage-backed — — 215,521 99,188 86,205 400,914 Commercial mortgage-backed — — 534,357 49,046 230,343 813,746 Asset-backed — — 441,393 152,161 76,681 670,235 Total fixed maturity and short-term investments $ 51,490 $ 128,335 $ 6,143,335 $ 1,538,052 $ 1,173,345 $ 9,034,557 Included within residential and commercial mortgage-backed securities as of December 31, 2020 were securities issued by U.S. governmental agencies with a fair value of $458.1 million (as of December 31, 2019: $333.3 million). There were no senior secured loans within corporate securities as of December 31, 2020, compared to $31.4 million as of December 31, 2019. Contractual Maturities The contractual maturities of our short-term and fixed maturity investments, classified as trading and AFS, and the fixed maturity investments included within our funds held - directly managed balance are shown below. Actual maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. As of December 31, 2020 Amortized Cost Fair Value % of Total Fair Value One year or less $ 489,559 $ 494,490 5.3 % More than one year through two years 710,621 726,331 7.8 % More than two years through five years 2,097,923 2,206,020 23.7 % More than five years through ten years 1,974,838 2,151,191 23.1 % More than ten years 1,544,533 1,775,652 19.0 % Residential mortgage-backed 545,628 553,945 5.9 % Commercial mortgage-backed 828,155 854,090 9.2 % Asset-backed 567,638 557,460 6.0 % $ 8,758,895 $ 9,319,179 100.0 % Credit Ratings The following table sets forth the credit ratings of our short-term and fixed maturity investments, classified as trading and AFS, and the fixed maturity investments included within our funds held - directly managed balance as of December 31, 2020: Amortized Fair Value % of Total AAA AA Rated A Rated BBB Non- Not Rated U.S. government and agency $ 935,014 $ 951,048 10.2 % $ 951,048 $ — $ — $ — $ — $ — U.K. government 46,988 51,082 0.6 % — 43,199 7,883 — — — Other government 463,765 502,153 5.4 % 244,041 159,095 42,337 51,413 5,267 — Corporate 5,226,238 5,686,732 61.0 % 172,718 607,796 2,646,602 1,960,971 287,363 11,282 Municipal 145,469 162,669 1.7 % 8,270 78,585 55,631 20,183 — — Residential mortgage-backed 545,628 553,945 5.9 % 544,545 — 2,195 2,615 2,472 2,118 Commercial mortgage-backed 828,155 854,090 9.2 % 591,396 115,114 74,615 61,730 3,961 7,274 Asset-backed 567,638 557,460 6.0 % 239,733 84,058 119,757 89,898 24,014 — Total $ 8,758,895 $ 9,319,179 100.0 % $ 2,751,751 $ 1,087,847 $ 2,949,020 $ 2,186,810 $ 323,077 $ 20,674 % of total fair value 29.5 % 11.7 % 31.6 % 23.5 % 3.5 % 0.2 % Unrealized Gains and Losses on AFS Short-Term and Fixed Maturity Investments The amortized cost, unrealized gains and losses, allowance for credit losses and fair values of our short-term and fixed maturity investments classified as AFS as of December 31, 2020 were as follows: Gross Unrealized Losses 2020 Amortized Cost Gross Unrealized Gains Non-Credit Related Losses Allowance for Credit Losses (1) Fair Value U.S. government and agency $ 715,527 $ 3,305 $ (834) $ — $ 717,998 U.K. government 12,494 1,080 — — 13,574 Other government 142,459 7,721 (53) — 150,127 Corporate 1,873,184 65,913 (1,567) (181) 1,937,349 Municipal 28,881 1,155 (4) — 30,032 Residential mortgage-backed 326,268 3,292 (689) — 328,871 Commercial mortgage-backed 273,516 5,202 (2,097) (133) 276,488 Asset-backed 204,312 846 (694) (8) 204,456 $ 3,576,641 $ 88,514 $ (5,938) $ (322) $ 3,658,895 (1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 1 - "Significant Accounting Policies" for further details. The amortized cost, unrealized gains and losses and fair values of our short-term and fixed maturity investments classified as AFS as of December 31, 2019 were as follows: 2019 Amortized Gross Gross Fair U.S. government and agency $ 381,488 $ 78 $ (322) $ 381,244 U.K. government 15,067 282 — 15,349 Other government 84,116 1,119 (88) 85,147 Corporate 880,667 3,739 (3,934) 880,472 Municipal 3,770 12 (2) 3,780 Residential mortgage-backed 99,646 221 (679) 99,188 Commercial mortgage-backed 49,219 30 (203) 49,046 Asset-backed 152,153 127 (119) 152,161 $ 1,666,126 $ 5,608 $ (5,347) $ 1,666,387 Gross Unrealized Losses on AFS Short-term and Fixed Maturity Investments The following table summarizes our short-term and fixed maturity investments classified as AFS that were in a gross unrealized loss position, for which an allowance for credit losses has not been recorded, as of December 31, 2020: 12 Months or Greater Less Than 12 Months Total 2020 Fair Gross Unrealized Fair Gross Unrealized Fair Gross Unrealized U.S. government and agency $ — $ — $ 55,839 $ (834) $ 55,839 $ (834) UK government — — — — — — Other government — — 7,971 (53) 7,971 (53) Corporate — — 199,048 (1,224) 199,048 (1,224) Municipal — — 1,690 (4) 1,690 (4) Residential mortgage-backed 4,626 (125) 79,149 (564) 83,775 (689) Commercial mortgage-backed 38 (38) 67,094 (1,562) 67,132 (1,600) Asset-backed — — 116,827 (564) 116,827 (564) Total short-term and fixed maturity investments $ 4,664 $ (163) $ 527,618 $ (4,805) $ 532,282 $ (4,968) The following table summarizes our short-term and fixed maturity investments classified as AFS that were in a gross unrealized loss position as of December 31, 2019, aggregated by major security type and length of time in continuous unrealized loss position: 12 Months or Greater Less Than 12 Months Total 2019 Fair Gross Unrealized Fair Gross Unrealized Fair Gross Unrealized U.S. government and agency $ — $ — $ 193,574 $ (322) $ 193,574 $ (322) Other government 1,080 (23) 37,796 (65) 38,876 (88) Corporate 2,754 (306) 338,965 (3,628) 341,719 (3,934) Municipal 128 — 761 (2) 889 (2) Residential mortgage-backed — — 52,005 (679) 52,005 (679) Commercial mortgage-backed — — 35,777 (203) 35,777 (203) Asset-backed — — 101,591 (119) 101,591 (119) Total short-term and fixed maturity investments $ 3,962 $ (329) $ 760,469 $ (5,018) $ 764,431 $ (5,347) Allowance for Credit Losses on AFS Fixed Maturity Investments We adopted ASU 2016-13 and the related amendments on January 1, 2020 prospectively, and recognized an allowance for credit losses of $3.1 million on initial adoption of the guidance. Our allowance for credit losses is derived based on various data sources, multiple key inputs and forecast scenarios. These include default rates specific to the individual security, vintage of the security, geography of the issuer of the security, industry analyst reports, credit ratings and consensus economic forecasts. To determine the credit losses on our AFS securities, we use the probability of default ("PD") and loss given default ("LGD") methodology through a third-party proprietary tool which calculates the expected credit losses based on a discounted cash flow method. The tool uses effective interest rates to discount the expected cash flows associated with each AFS security to determine its fair value, which is then compared with its amortized cost basis to derive the credit loss on the security. The methodology and inputs used to determine the credit loss by security type are as follows: • Corporate and Government: Expected cashflows are derived that are specific to each security. The PD is based on a quantitative model that converts agency ratings to term structures that vary by country, industry and the state of the credit cycle. This is used along with macroeconomic forecasts to produce scenario conditioned PDs. The LGD is based on default studies provided by a third party which we use along with macroeconomic forecasts to produce scenario conditioned LGDs. • Municipals : Expected cash flows are derived that are specific to each security. The PD model produces scenario conditioned PD output over the lifetime of the municipal security. These PDs are based on key macroeconomic and instrument specific risk factors. The LGD is derived based on a model which uses assumptions specific to the municipal securities. For corporate, government and municipal securities, we use an explicit reversion and a three year forecast period, which we consider to be a reasonable duration during which an economic forecast could continue to be reliable. • Asset backed, Commercial and Residential mortgaged-backed: Expected cash flows are derived that are specific to each security. The PD and LGD for each security is based on a quantitative model that generates scenario conditioned PD and LGD term structures based on the underlying collateral type, waterfall and other trustee information. This model also considers prepayments. For these security types, there is no explicit reversion and the forecasts are deemed reasonable and supportable over the life of the portfolio. Due to the short-term period during which accrued investment income remains unpaid, which is typically six months or less since the coupon on our debt securities is paid semi-annually or more frequently, we elected not to establish an allowance for credit losses on our accrued investment income balances. Accrued investment income is written off through net realized investment gains (losses) at the time the issuer of the debt security defaults or is expected to default on payments. The following table provides a reconciliation of the beginning and ending allowance for credit losses on our AFS debt securities: December 31, 2020 Other Corporate Residential mortgage-backed Commercial Asset-backed Total Allowance for credit losses, beginning of year $ — $ — $ — $ — $ — $ — Cumulative effect of change in accounting principle (22) (2,987) — (50) — (3,059) Allowances for credit losses on securities for which credit losses were not previously recorded — (10,748) (2) (675) (142) (11,567) Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets — — — — — — Reductions for securities sold during the year 22 2,545 — — — 2,567 Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis — — — — — — (Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period — 11,009 2 592 134 11,737 Allowance for credit losses, end of year $ — $ (181) $ — $ (133) $ (8) $ (322) During the year ended December 31, 2020, we did not have any write-offs charged against the allowance for credit losses or any recoveries of amounts previously written-off. Other-Than-Temporary Impairment on AFS Short-term and Fixed Maturity Investments For the years ended December 31, 2019 and 2018, we did not recognize any OTTI losses on our AFS securities. We determined that no other-than-temporary credit losses existed as of December 31, 2019. A description of our OTTI process is included in Note 2 - "Significant Accounting Policies". As discussed in detail in Note 2 - "Significant Accounting Policies", we adopted ASU 2016-13 and the related amendments on January 1, 2020 with this new guidance replacing the OTTI model that was previously applicable to our AFS debt securities. The new approach now requires the recognition of impairments relating to credit losses through an allowance account and limits the amount of credit loss to the difference between a security’s amortized cost basis and its fair value. Equity Investments The following table summarizes our equity investments classified as trading as of December 31, 2020 and 2019: 2020 2019 Publicly traded equity investments in common and preferred stocks $ 260,767 $ 327,875 Exchange-traded funds 311,287 133,047 Privately held equity investments in common and preferred stocks 274,741 265,799 $ 846,795 $ 726,721 Equity investments include publicly traded common and preferred stocks, exchange-traded funds and privately held common and preferred stocks. Our publicly traded equity investments in common and preferred stocks predominantly trade on major exchanges and are managed by our external advisors. Our investments in exchange-traded funds also trade on major exchanges. Other Investments, at fair value The following table summarizes our other investments carried at fair value as of December 31, 2020 and 2019: 2020 2019 Hedge funds $ 2,638,339 $ 1,121,904 Fixed income funds 552,541 481,039 Private equity funds 363,103 323,496 Private credit funds 192,319 — Equity funds 190,767 410,149 CLO equity funds 166,523 87,509 CLO equities 128,083 87,555 Others 12,359 6,379 $ 4,244,034 $ 2,518,031 The valuation of our other investments is described in Note 12 - "Fair Value Measurements". Due to a lag in the valuations of certain funds reported by the managers, we may record changes in valuation with up to a three-month lag. We regularly review and discuss fund performance with the fund managers to corroborate the reasonableness of the reported net asset values and to assess whether any events have occurred within the lag period that would affect the valuation of the investments. The following is a description of the nature of each of these investment categories: • Hedge funds may invest in a wide range of instruments, including debt and equity securities, and utilize various sophisticated strategies, including derivatives, to achieve their objectives. We invest in fixed income, equity and multi-strategy hedge funds. • 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, in both liquid and illiquid markets. The liquid fixed income funds have regularly published prices. • Private equity funds invest primarily in the financial services industry. • Private credit funds invest in direct senior or collateralized loans. • Equity funds invest in a diversified portfolio of U.S. and international publicly-traded equity securities. • CLO equity funds invest primarily in the equity tranches of term-financed securitizations of diversified pools of corporate bank loans. • CLO equities comprise investments in the equity tranches of term-financed securitizations of diversified pools of corporate bank loans. • Others primarily comprise of a real estate debt fund that invests primarily in European commercial real estate equity. The increase in our other investments carried at fair value between December 31, 2020 and December 31, 2019 was primarily attributable to unrealized gains of $1.3 billion and net additional subscriptions of $380.3 million to hedge funds, fixed income funds, private credit funds, CLO equities and CLO equity funds. As of December 31, 2020, we had unfunded commitments of $975.5 million to other investments. Certain of our other investments are subject to restrictions on redemptions and sales that are determined by the governing documents, which limits our ability to liquidate those investments. These restrictions may include lock-ups, redemption gates, restricted share classes or side pockets, restrictions on the frequency of redemption and notice periods. 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. Certain other investments may not have any restrictions governing their sale, but there is no active market and no guarantee that we will be able to execute a sale in a timely manner. In addition, even if certain other investments are not eligible for redemption or sales are restricted, we may still receive income distributions from those other investments. The table below details the estimated date by which proceeds would be received if we had provided notice of our intent to redeem or initiated a sales process as of December 31, 2020: Less than 1 Year 1-2 years 2-3 years More than 3 years Not Eligible/ Restricted Total Redemption Frequency Hedge funds $ 2,590,164 $ — $ — $ — $ 48,175 $ 2,638,339 Monthly to Bi-annually Fixed income funds 537,055 — — — 15,486 552,541 Daily to Quarterly Equity funds 190,767 — — — — 190,767 Daily to Quarterly Private equity funds — — — — 363,103 363,103 N/A CLO equity funds 94,313 61,741 10,469 — — 166,523 Quarterly to Bi-annually CLO equities 128,083 — — — — 128,083 Daily to Quarterly Private credit funds — 9,250 — 183,069 192,319 N/A Other 12,359 12,359 N/A $ 3,540,382 $ 70,991 $ 10,469 $ — $ 622,192 $ 4,244,034 As of December 31, 2020 and 2019, we had $48.2 million and $51.8 million, respectively, of hedge funds subject to gates or side-pockets. Equity Method Investments The table below shows our equity method investments as of December 31, 2020 and 2019: 2020 2019 Ownership % Carrying Value Ownership % Carrying Value Enhanzed Re 47.4 % $ 330,289 47.4 % $ 182,856 Citco (1) 31.9 % 53,022 31.9 % 51,742 Monument Re (2) 20.0 % 193,716 20.0 % 60,598 Clear Spring — % — 20.0 % 10,645 Core Specialty 25.2 % 235,000 — % — Other 27% 20,268 30% 20,436 $ 832,295 $ 326,277 (1 ) We own 31.9% of the common shares in HH CTCO Holdings Limited which in turn owns 15.4% of the convertible preferred shares, amounting to a 6.2% interest in the total equity of Citco III Limited ("Citco"). (2) We own 20.0% of the common shares in Monument Re as well as different classes of preferred shares which have fixed dividend yields and whose balances are included in the Investment amount. Refer to Note 21 - "Related Party Transactions" for further information regarding the investments above. As of December 31, 2020, we had unfunded commitments of $68.7 million related to equity method investments. Funds Held - Directly Managed Funds held - directly managed, where we receive the underlying return on the investment portfolio, are carried at fair value, either because we elected the fair value option at the inception of the reinsurance contract, or because it represents the aggregate of funds held at amortized cost and the fair value of an embedded derivative. The embedded derivative relates to our contractual right to receive the return on the underlying investment portfolio supporting the reinsurance contract. We include the estimated fair value of these embedded derivatives in the consolidated balance sheets with the host contract in order to reflect the expected settlement of these features with the host contract. The change in the fair value of the embedded derivative is included in net unrealized gains (losses). The following table summarizes the components of the funds held - directly managed as of December 31, 2020 and 2019: 2020 2019 Fixed maturity investments, trading $ 1,060,263 $ 1,173,345 Cash and cash equivalents 9,067 10,296 Other assets 5,560 3,911 $ 1,074,890 $ 1,187,552 The following table summarizes the short-term and fixed maturity investment components of funds held - directly managed as of December 31, 2020 and 2019: 2020 2019 Funds held - Directly Managed - Fair Value Option Funds held - Directly Managed - Variable Return Total Funds held - Directly Managed - Fair Value Option Funds held - Directly Managed - Variable Return Total Short-term and fixed maturity investments, at amortized cost $ 106,938 $ 859,403 $ 966,341 $ 185,859 $ 940,194 $ 1,126,053 Net unrealized gains (losses): Change in fair value - fair value option accounting 9,693 — 9,693 5,438 — 5,438 Change in fair value - embedded derivative accounting — 84,229 84,229 — 41,854 41,854 Short-term and fixed maturity investments within funds held - directly managed, at fair value $ 116,631 $ 943,632 $ 1,060,263 $ 191,297 $ 982,048 $ 1,173,345 Refer to the sections above for details of the short-term and fixed maturity investments within our funds held - directly managed portfolios. Funds Held by Reinsured Companies Funds held by reinsured companies, where we received a fixed crediting rate, are carried at cost on our consolidated balance sheets. As of December 31, 2020 and 2019, we had funds held by reinsured companies of $635.8 million and $475.7 million, respectively. The increase related to $204.2 million of additional funds held balances related to the AXA Group transaction. Net Investment Income Major categories of net investment income for the years ended December 31, 2020, 2019 and 2018 are summarized as follows: 2020 2019 2018 Fixed maturity investments $ 198,988 $ 217,886 $ 178,213 Short-term investments and cash and cash equivalents 4,843 15,609 11,692 Funds held 33,920 22,580 11,640 Funds held – directly managed 34,563 38,173 37,623 Investment income from fixed maturities and cash and cash equivalents 272,314 294,248 239,168 Equity investments 19,240 16,671 5,397 Other investments 27,153 11,792 26,214 Investment income from equities and other investments 46,393 28,463 31,611 Gross investment income 318,707 322,711 270,779 Investment expenses (15,890) (14,440) (9,081) Net investment income $ 302,817 $ 308,271 $ 261,698 Net Realized and Unrealized Gains (Losses) Components of net realized and unrealized gains (losses) for the years ended December 31, 2020, 2019 and 2018 were as follows: 2020 2019 2018 Net realized gains (losses) on sale: Gross realized gains on fixed maturity securities, AFS $ 26,313 $ 4,844 $ 27 Gross realized losses on fixed maturity securities, AFS (7,801) (905) (90) Decrease in allowance for expected credit losses on fixed maturity securities, AFS 170 — — Net realized gains (losses) on fixed maturity securities, trading 126,945 81,011 (27,408) Net realized gains (losses) on fixed maturity securities in funds held - directly managed 8,798 1,495 (3,940) Net realized gains (losses) on equity investments 24,282 (374) 4,016 Net realized investment gains on investment derivatives 144 — — Total net realized gains (losses) on sale 178,851 86,071 (27,395) Net unrealized gains (losses): Fixed maturity securities, trading 101,022 341,130 (159,594) Fixed maturity securities in funds held - directly managed 50,837 88,053 (46,257) Equity investments (25,752) 55,359 (9,831) Other investments 1,336,343 441,702 (164,455) Investment derivatives 718 (349) — Total net unrealized gains (losses) 1,463,168 925,895 (380,137) Net realized and unrealized gains (losses) $ 1,642,019 $ 1,011,966 $ (407,532) The gross realized gains and losses on AFS investments included in the table above resulted from sales of $2.0 billion, $302.9 million and $11.4 million for the years ended December 31, 2020, 2019 and 2018, respectively. The unrealized gains for 2020 primarily comprised unrealized gains of $1.2 billion in the hedge fund managed by AnglePoint. These unrealized gains were driven by strong performance in equity markets across multiple sectors, including consumer discretionary, communication services, information technology and consumer staples. Reconciliation to the Consolidated Statements of Comprehensive Income The following table provides a reconciliation of the gross realized gains and losses and credit recoveries (losses) on our AFS fixed maturity debt securities that arose during the years ended December 31, 2020, 2019 and 2018 within our continuing and discontinued operations and the offsetting reclassification adjustments included within our consolidated statements of comprehensive income: 2020 2019 2018 Included within continuing operations: Gross realized gains on fixed maturity securities, AFS $ 26,313 $ 4,844 $ 27 Gross realized losses on fixed maturity securities, AFS (7,801) (905) (90) Tax effect (1,623) — — Included within discontinued operations: Gross realized gains on fixed maturity securities, AFS 1,374 12 — Gross realized losses on fixed maturity securities, AFS (120) (57) — Tax effect (110) — — Total reclassification adjustment for net realized gains (losses) included in net earnings $ 18,033 $ 3,894 $ (63) Included within continuing operations: Credit recoveries (losses) on fixed maturity securities, AFS $ 170 $ — $ — Tax effect 3 — — Included within discontinued operations: Credit recoveries (losses) on fixed maturity securities, AFS 329 — — Tax effect 7 — — Total reclassification adjustment for change in allowance for credit losses recognized in net earnings $ 509 $ — $ — Restricted Assets We utilize trust accounts to collateralize business with our (re)insurance counterparties. We are also required to maintain investments and cash and cash equivalents on deposit with regulatory authorities and Lloyd's to support our (re)insurance operations. The investments and cash and cash equivalents on deposit are available to settle (re)insurance liabilities. Collateral generally takes the form of assets held in trust, letters of credit or funds held. The assets used as collateral are primarily highly rated fixed maturity securities. The carrying value of our restricted assets, including restricted cash of $472.0 million and $346.9 million, as of December 31, 2020 and 2019, respectively, was as follows: 2020 2019 Collateral in trust for third party agreements $ 4,924,866 $ 4,103,847 Assets on deposit with regulatory authorities 131,283 309,659 Collateral for secured letter of credit facilities 104,627 132,670 Funds at Lloyd's (1) 260,914 639,316 $ 5,421,690 $ 5,185,492 (1) Our businesses include three Lloyd's syndicates as at December 31, 2020. Lloyd's determines the required capital principally through the annual business plan of each syndicate. This capital is referred to as "Funds at Lloyd's" and will be drawn upon in the event that a syndicate has a loss that cannot be funded from other sources. We also utilize unsecured letters of credit for Funds at Lloyd's, as described in Note 15 - "Debt Obligations and Credit Facilities".

Derivatives and Hedging Instrum

Derivatives and Hedging Instruments	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging Instruments	7. DERIVATIVES 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. As of December 31, 2020 and 2019, we had foreign currency forward exchange rate 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 of December 31, 2020 and 2019: 2020 2019 Fair Value Fair Value Gross Notional Amount Assets Liabilities Gross Notional Amount Assets Liabilities Foreign currency forward - AUD $ 73,852 $ 13 $ 5,060 $ 64,620 $ 52 $ 2,033 Foreign currency forward - EUR 217,168 205 8,889 112,284 246 1,635 Foreign currency forward - GBP 312,671 951 14,998 318,387 344 7,784 Total qualifying hedges $ 603,691 $ 1,169 $ 28,947 $ 495,291 $ 642 $ 11,452 The following table presents the net gains and losses deferred in the cumulative translation adjustment ("CTA") account, which is a component of AOCI, in shareholders' equity, relating to our foreign currency forward exchange rate contracts for the years ended December 31, 2020, 2019 and 2018: Amount of Gains (Losses) Deferred in AOCI 2020 2019 2018 Foreign currency forward - AUD $ (6,792) $ (722) $ 3,438 Foreign currency forward - EUR (15,026) 1,817 1,000 Foreign currency forward - GBP (8,457) (16,423) — Total qualifying hedges $ (30,275) $ (15,328) $ 4,438 Non-derivative Hedging Instruments of Net Investments in Foreign Operations Derivatives Not Designated or Not Qualifying as Net Investments in 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 or other derivatives either to obtain exposure to a particular equity instrument or for yield enhancement in non-qualifying hedging relationships. Foreign Currency Forward Contracts The following tables present the gross notional amounts and estimated fair values recorded within other assets and other liabilities related to our non-qualifying foreign currency forward exchange rate hedging relationships as of December 31, 2020 and 2019: December 31, 2020 December 31, 2019 Fair Value Fair Value Gross Notional Amount Assets Liabilities Gross Notional Amount Assets Liabilities Foreign currency forward - AUD $ 28,848 $ 882 $ 2,847 $ 913 $ 839 $ 892 Foreign currency forward - CAD 64,224 10 1,764 66,266 10 1,482 Foreign currency forward - EUR 43,531 1,782 41 74,444 507 1,440 Foreign currency forward - GBP 2,731 161 404 11,940 13 292 Total non-qualifying hedges $ 139,334 $ 2,835 $ 5,056 $ 153,563 $ 1,369 $ 4,106 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 years ended December 31, 2020, 2019, and 2018: Gains (losses) on non-qualifying hedges charged to earnings 2020 2019 2018 Foreign currency forward - AUD $ (2,388) $ 1,523 $ 4,958 Foreign currency forward - CAD (879) (2,079) 9,311 Foreign currency forward - EUR 1,871 1,759 2,296 Foreign currency forward - GBP (1,558) 12,004 15,078 Net gains (losses) on non-qualifying hedges $ (2,954) $ 13,207 $ 31,643 Investments in Call Options on Equities During the years ended December 31, 2020, 2019, and 2018, we recorded unrealized gains (losses) of less than $(0.1) million, $0.5 million and $(9.4) million, respectively, in net earnings on the call options on equities that we had purchased in 2018 at a cost of $10.0 million. These call options on equities had a fair value of less than $0.1 million as of December 31, 2019 and expired without being exercised during the year ended December 31, 2020. Forward Interest Rate Swaps In 2019, we entered into a forward interest rate swap, with a notional amount of AUD$120.0 million, to partially mitigate the risk associated with declining interest rates until the completion of the Munich Re transaction which closed on July 1, 2020, as described in Note 4 - "Significant New Business". During the year ended December 31, 2020, we recorded unrealized gains included within net earnings of $0.8 million on the forward interest rate swap. This forward interest rate swap was terminated on April 7, 2020, for an inception-to-date net realized gain of $0.5 million. The carrying value of the forward interest rate swap, recorded in other liabilities as of December 31, 2019, was $0.3 million. Credit Default Swaps, Futures and Currency Forward Contracts From time to time we may also utilize (i) credit default swaps to both hedge and replicate credit exposure, (ii) government bond futures contracts for interest rate management, and (iii) foreign currency forward contracts for currency hedging, to collectively manage credit and duration risk, as well as for yield enhancement on some of our fixed income portfolios. The following table presents the gross notional amounts and estimated fair values recorded within other assets and other liabilities related to our credit default swaps, government bond futures contracts and currency forward contracts: December 31, 2020 Fair Value Gross Notional Amount Assets Liabilities Futures contracts - long positions $ 34,502 $ 32 $ 5 Futures contracts - short positions (32,316) 6 121 Currency forward contracts - long positions - USD 1,428 — 13 Currency forward contracts - short positions - USD (3,233) 60 — Currency forward contracts - long positions - GBP 1,278 19 — Currency forward contracts - short positions - GBP (4,418) 12 — Total $ (2,759) $ 129 $ 139 The following table presents the amounts of the net gains included in earnings related to our credit default swaps, government bond futures contracts and currency forward contracts: 2020 Credit default swaps $ 181 Futures contracts (127) Currency forward contracts 572 Total net gains $ 626

Reinsurance Balances Recoverabl

Reinsurance Balances Recoverable on Paid and Unpaid Losses	12 Months Ended
	Dec. 31, 2020
Insurance [Abstract]
Reinsurance Balances Recoverable on Paid and Unpaid Losses	$1 million 539,428 158,174 697,602 33.4 % Other reinsurers < $1 million 23,765 3,203 26,968 1.3 % Total $ 1,599,869 $ 489,294 $ 2,089,163 100.0 % December 31, 2019 Non-life Atrium StarStone Total % of Top 10 reinsurers $ 1,154,110 $ 22,051 $ 295,443 $ 1,471,604 67.4 % Other reinsurers > $1 million 551,636 7,761 129,335 688,732 31.6 % Other reinsurers < $1 million 19,243 545 1,010 20,798 1.0 % Total $ 1,724,989 $ 30,357 $ 425,788 $ 2,181,134 100.0 % December 31, 2020 December 31, 2019 Information regarding top ten reinsurers: Number of top 10 reinsurers rated A- or better 7 8 Number of top 10 non-rated reinsurers (1) 3 2 Reinsurers rated A- or better in top 10 $ 863,819 $ 1,199,479 Non-rated reinsurers in top 10 (1) 500,774 272,125 Total top 10 reinsurance recoverables $ 1,364,593 $ 1,471,604 Single reinsurers that represent 10% or more of total reinsurance balance recoverables as of December 31, 2020 and 2019: Hannover Ruck SE (2) $ — $ 259,077 Lloyd's Syndicates (3) $ 331,118 $ 396,246 Michigan Catastrophic Claims Association (4) $ 229,374 $ — (1) The reinsurance balances recoverable from the three and two non-rated top 10 reinsurers as of December 31, 2020 and 2019, respectively, was comprised of: • $229.4 million and $190.8 million as of December 31, 2020 and December 31, 2019 respectively, due from a U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state; • $73.8 million and $81.4 million as of December 31, 2020 and December 31, 2019 respectively, due from a reinsurer who has provided us with security in the form of pledged assets in trust for the full amount of the recoverable balance; and • $208.4 million as of December 31, 2020 due from Enhanzed Re, an equity method investee to whom some of our subsidiaries have retroceded their exposures through quota share reinsurance agreements as discussed in Note 21 - "Related Party Transactions". These quota share reinsurance agreements are written on a funds withheld basis with our subsidiaries retaining the retrocession premium consideration, to secure the full amount of the recoverable balances due from Enhanzed Re. (2) Hannover Ruck SE is rated AA- by Standard & Poor’s and A+ by A.M. Best. The transaction described in Note 4 - "Significant New Business" had the effect of reducing the balances due from this reinsurer to below 10% of the total reinsurance balances recoverable as of December 31, 2020. (3) Lloyd's Syndicates are rated A+ by Standard & Poor's and A by A.M. Best. (4) U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state. We evaluate and monitor the credit risk related to our reinsurers, and an allowance for estimated uncollectible reinsurance balances recoverable on paid and unpaid losses ("allowance for estimated uncollectible reinsurance") is established for amounts considered potentially uncollectible. With respect to our process for determining the allowances for estimated uncollectible reinsurance, we adopted ASU 2016-13 and the related amendments on January 1, 2020 and recorded a cumulative effect adjustment of $0.2 million to increase the opening retained earnings on the initial adoption of the guidance. Our allowance for estimated uncollectible reinsurance is derived based on various data sources, multiple key inputs and forecast scenarios. These include the duration of the collection period, credit quality, changes in reinsurer credit standing, default rates specific to the individual reinsurer, the geographical location of the reinsurer, contractual disputes with reinsurers over individual contentious claims, contract language or coverage issues, industry analyst reports and consensus economic forecasts. To determine the allowance for estimated uncollectible reinsurance, we use the PD and LGD methodology whereby each reinsurer is allocated an appropriate PD percentage based on the expected payout duration by portfolio. This PD percentage is then multiplied by an appropriate LGD percentage to arrive at an overall credit allowance percentage which is then applied to the reinsurance balance recoverable for each reinsurer, net of any specific bad debt provisions, collateral or other contract related offsets, to arrive at the overall allowance for estimated uncollectible reinsurance by reinsurer. The following tables show our gross and net balances recoverable from our reinsurers as well as the related allowance for estimated uncollectible reinsurance broken down by the credit ratings of our reinsurers. The majority of the allowance for estimated uncollectible reinsurance relates to the Non-life Run-off segment. December 31, 2020 Gross Allowance for estimated uncollectible reinsurance Net Provisions as a Reinsurers rated A- or above $ 1,464,529 $ 60,801 $ 1,403,728 4.2 % Reinsurers rated below A-, secured 608,999 — 608,999 — % Reinsurers rated below A-, unsecured 152,757 76,321 76,436 50.0 % Total $ 2,226,285 $ 137,122 $ 2,089,163 6.2 % December 31, 2019 Gross Allowance for estimated uncollectible reinsurance Net Provisions as a Reinsurers rated A- or above $ 1,731,270 $ 43,427 $ 1,687,843 2.5 % Reinsurers rated below A-, secured 463,840 — 463,840 — % Reinsurers rated below A-, unsecured 133,663 104,212 29,451 78.0 % Total $ 2,328,773 $ 147,639 $ 2,181,134 6.3 % The table below provides a reconciliation of the beginning and ending allowance for estimated uncollectible reinsurance balances for the years ended December 31, 2020 and 2019: 2020 2019 Allowance for estimated uncollectible reinsurance, beginning of year $ 147,639 $ 156,732 Cumulative effect of change in accounting principle (195) — Effect of exchange rate movement 700 (887) Current period change in the allowance (381) 2,077 Write-offs charged against the allowance (9,625) (9,871) Recoveries collected (1,016) (412) Allowance for estimated uncollectible reinsurance, end of year $ 137,122 $ 147,639 13. PREMIUMS WRITTEN AND EARNED The following tables provide a summary of net premiums written and earned for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Premiums Premiums Premiums Premiums Premiums Premiums Non-life Run-off Gross $ 5,191 $ 71,522 $ (25,069) $ 197,009 $ (8,910) $ 25,230 Ceded (2,204) (12,827) (269) (28,513) (307) (15,803) Net $ 2,987 $ 58,695 $ (25,338) $ 168,496 $ (9,217) $ 9,427 Atrium Gross $ 206,656 $ 197,492 $ 192,373 $ 182,678 $ 171,494 $ 164,428 Ceded (23,462) (22,099) (20,017) (18,619) (18,006) (18,113) Net $ 183,194 $ 175,393 $ 172,356 $ 164,059 $ 153,488 $ 146,315 StarStone Gross $ 326,695 $ 441,015 $ 472,815 $ 549,299 $ 622,570 $ 647,218 Ceded (93,493) (122,900) (93,292) (98,187) (144,561) (132,055) Net $ 233,202 $ 318,115 $ 379,523 $ 451,112 $ 478,009 $ 515,163 Other Gross $ 13,441 $ 19,889 $ 18,534 $ 20,544 $ 32,378 $ 25,237 Ceded — — (22) (164) (311) (363) Net $ 13,441 $ 19,889 $ 18,512 $ 20,380 $ 32,067 $ 24,874 Total Gross $ 551,983 $ 729,918 $ 658,653 $ 949,530 $ 817,532 $ 862,113 Ceded (119,159) (157,826) (113,600) (145,483) (163,185) (166,334) Net $ 432,824 $ 572,092 $ 545,053 $ 804,047 $ 654,347 $ 695,779 " id="sjs-B4" xml:space="preserve">8. REINSURANCE BALANCES RECOVERABLE ON PAID AND UNPAID LOSSES The following tables provide the total reinsurance balances recoverable on paid and unpaid losses. December 31, 2020 Non-life StarStone Total Recoverable from reinsurers on unpaid: Outstanding losses $ 938,231 $ 263,638 $ 1,201,869 IBNR 508,082 139,761 647,843 ULAE 16,688 — 16,688 Fair value adjustments - acquired companies (14,014) (1,339) (15,353) Fair value adjustments - fair value option (21,427) — (21,427) Total reinsurance reserves recoverable 1,427,560 402,060 1,829,620 Paid losses recoverable 172,309 87,234 259,543 Total $ 1,599,869 $ 489,294 $ 2,089,163 Reconciliation to Consolidated Balance Sheet: Reinsurance balances recoverable on paid and unpaid losses $ 1,079,039 $ 489,294 $ 1,568,333 Reinsurance balances recoverable on paid and unpaid losses - fair value option 520,830 — 520,830 Total $ 1,599,869 $ 489,294 $ 2,089,163 December 31, 2019 Non-life Atrium StarStone Total Recoverable from reinsurers on unpaid: Outstanding losses $ 972,293 $ 9,011 $ 264,131 $ 1,245,435 IBNR 673,059 19,286 93,185 785,530 Fair value adjustments - acquired companies (13,652) 519 (2,122) (15,255) Fair value adjustments - fair value option (88,086) — — (88,086) Total reinsurance reserves recoverable 1,543,614 28,816 355,194 1,927,624 Paid losses recoverable 181,375 1,541 70,594 253,510 Total $ 1,724,989 $ 30,357 $ 425,788 $ 2,181,134 Reconciliation to Consolidated Balance Sheet: Reinsurance balances recoverable on paid and unpaid losses $ 1,029,471 $ 30,357 $ 425,788 $ 1,485,616 Reinsurance balances recoverable on paid and unpaid losses - fair value option 695,518 — — 695,518 Total $ 1,724,989 $ 30,357 $ 425,788 $ 2,181,134 Our (re)insurance run-off subsidiaries and assumed portfolios, prior to acquisition, used retrocessional agreements to reduce their exposure to the risk of (re)insurance assumed. On an annual basis, both Atrium (classified as held-for-sale as of December 31, 2020) and StarStone purchased a tailored outwards reinsurance program designed to manage their risk profiles. The majority of Atrium’s and StarStone's third-party reinsurance is with highly rated reinsurers or is collateralized by pledged assets or letters of credit. The fair value adjustments, determined on acquisition of (re)insurance subsidiaries, are based on the estimated timing of loss and LAE recoveries and an assumed interest rate equivalent to a risk free rate for securities with similar duration to the acquired reinsurance balances recoverable on paid and unpaid losses plus a spread for credit risk, and are amortized over the estimated recovery period, as adjusted for accelerations in timing of payments as a result of commutation settlements. The determination of the fair value adjustments on the retroactive reinsurance contracts for which we have elected the fair value option is described in Note 12 - "Fair Value Measurements". As of December 31, 2020 and 2019, we had reinsurance balances recoverable on paid and unpaid losses of $2.1 billion and $2.2 billion, respectively. The decrease of $92.0 million was primarily due to the Hannover Re transaction, cash collections and the classification of Atrium as held-for-sale at December 31, 2020, partially offset by increases due to the retrocession to Enhanzed Re as discussed in Note 21 - "Related Party Transactions" Top Ten Reinsurers December 31, 2020 Non-life StarStone Total % of Top 10 reinsurers $ 1,036,676 $ 327,917 $ 1,364,593 65.3 % Other reinsurers > $1 million 539,428 158,174 697,602 33.4 % Other reinsurers < $1 million 23,765 3,203 26,968 1.3 % Total $ 1,599,869 $ 489,294 $ 2,089,163 100.0 % December 31, 2019 Non-life Atrium StarStone Total % of Top 10 reinsurers $ 1,154,110 $ 22,051 $ 295,443 $ 1,471,604 67.4 % Other reinsurers > $1 million 551,636 7,761 129,335 688,732 31.6 % Other reinsurers < $1 million 19,243 545 1,010 20,798 1.0 % Total $ 1,724,989 $ 30,357 $ 425,788 $ 2,181,134 100.0 % December 31, 2020 December 31, 2019 Information regarding top ten reinsurers: Number of top 10 reinsurers rated A- or better 7 8 Number of top 10 non-rated reinsurers (1) 3 2 Reinsurers rated A- or better in top 10 $ 863,819 $ 1,199,479 Non-rated reinsurers in top 10 (1) 500,774 272,125 Total top 10 reinsurance recoverables $ 1,364,593 $ 1,471,604 Single reinsurers that represent 10% or more of total reinsurance balance recoverables as of December 31, 2020 and 2019: Hannover Ruck SE (2) $ — $ 259,077 Lloyd's Syndicates (3) $ 331,118 $ 396,246 Michigan Catastrophic Claims Association (4) $ 229,374 $ — (1) The reinsurance balances recoverable from the three and two non-rated top 10 reinsurers as of December 31, 2020 and 2019, respectively, was comprised of: • $229.4 million and $190.8 million as of December 31, 2020 and December 31, 2019 respectively, due from a U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state; • $73.8 million and $81.4 million as of December 31, 2020 and December 31, 2019 respectively, due from a reinsurer who has provided us with security in the form of pledged assets in trust for the full amount of the recoverable balance; and • $208.4 million as of December 31, 2020 due from Enhanzed Re, an equity method investee to whom some of our subsidiaries have retroceded their exposures through quota share reinsurance agreements as discussed in Note 21 - "Related Party Transactions". These quota share reinsurance agreements are written on a funds withheld basis with our subsidiaries retaining the retrocession premium consideration, to secure the full amount of the recoverable balances due from Enhanzed Re. (2) Hannover Ruck SE is rated AA- by Standard & Poor’s and A+ by A.M. Best. The transaction described in Note 4 - "Significant New Business" had the effect of reducing the balances due from this reinsurer to below 10% of the total reinsurance balances recoverable as of December 31, 2020. (3) Lloyd's Syndicates are rated A+ by Standard & Poor's and A by A.M. Best. (4) U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state. We evaluate and monitor the credit risk related to our reinsurers, and an allowance for estimated uncollectible reinsurance balances recoverable on paid and unpaid losses ("allowance for estimated uncollectible reinsurance") is established for amounts considered potentially uncollectible. With respect to our process for determining the allowances for estimated uncollectible reinsurance, we adopted ASU 2016-13 and the related amendments on January 1, 2020 and recorded a cumulative effect adjustment of $0.2 million to increase the opening retained earnings on the initial adoption of the guidance. Our allowance for estimated uncollectible reinsurance is derived based on various data sources, multiple key inputs and forecast scenarios. These include the duration of the collection period, credit quality, changes in reinsurer credit standing, default rates specific to the individual reinsurer, the geographical location of the reinsurer, contractual disputes with reinsurers over individual contentious claims, contract language or coverage issues, industry analyst reports and consensus economic forecasts. To determine the allowance for estimated uncollectible reinsurance, we use the PD and LGD methodology whereby each reinsurer is allocated an appropriate PD percentage based on the expected payout duration by portfolio. This PD percentage is then multiplied by an appropriate LGD percentage to arrive at an overall credit allowance percentage which is then applied to the reinsurance balance recoverable for each reinsurer, net of any specific bad debt provisions, collateral or other contract related offsets, to arrive at the overall allowance for estimated uncollectible reinsurance by reinsurer. The following tables show our gross and net balances recoverable from our reinsurers as well as the related allowance for estimated uncollectible reinsurance broken down by the credit ratings of our reinsurers. The majority of the allowance for estimated uncollectible reinsurance relates to the Non-life Run-off segment. December 31, 2020 Gross Allowance for estimated uncollectible reinsurance Net Provisions as a Reinsurers rated A- or above $ 1,464,529 $ 60,801 $ 1,403,728 4.2 % Reinsurers rated below A-, secured 608,999 — 608,999 — % Reinsurers rated below A-, unsecured 152,757 76,321 76,436 50.0 % Total $ 2,226,285 $ 137,122 $ 2,089,163 6.2 % December 31, 2019 Gross Allowance for estimated uncollectible reinsurance Net Provisions as a Reinsurers rated A- or above $ 1,731,270 $ 43,427 $ 1,687,843 2.5 % Reinsurers rated below A-, secured 463,840 — 463,840 — % Reinsurers rated below A-, unsecured 133,663 104,212 29,451 78.0 % Total $ 2,328,773 $ 147,639 $ 2,181,134 6.3 % The table below provides a reconciliation of the beginning and ending allowance for estimated uncollectible reinsurance balances for the years ended December 31, 2020 and 2019: 2020 2019 Allowance for estimated uncollectible reinsurance, beginning of year $ 147,639 $ 156,732 Cumulative effect of change in accounting principle (195) — Effect of exchange rate movement 700 (887) Current period change in the allowance (381) 2,077 Write-offs charged against the allowance (9,625) (9,871) Recoveries collected (1,016) (412) Allowance for estimated uncollectible reinsurance, end of year $ 137,122 $ 147,639 13. PREMIUMS WRITTEN AND EARNED The following tables provide a summary of net premiums written and earned for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Premiums Premiums Premiums Premiums Premiums Premiums Non-life Run-off Gross $ 5,191 $ 71,522 $ (25,069) $ 197,009 $ (8,910) $ 25,230 Ceded (2,204) (12,827) (269) (28,513) (307) (15,803) Net $ 2,987 $ 58,695 $ (25,338) $ 168,496 $ (9,217) $ 9,427 Atrium Gross $ 206,656 $ 197,492 $ 192,373 $ 182,678 $ 171,494 $ 164,428 Ceded (23,462) (22,099) (20,017) (18,619) (18,006) (18,113) Net $ 183,194 $ 175,393 $ 172,356 $ 164,059 $ 153,488 $ 146,315 StarStone Gross $ 326,695 $ 441,015 $ 472,815 $ 549,299 $ 622,570 $ 647,218 Ceded (93,493) (122,900) (93,292) (98,187) (144,561) (132,055) Net $ 233,202 $ 318,115 $ 379,523 $ 451,112 $ 478,009 $ 515,163 Other Gross $ 13,441 $ 19,889 $ 18,534 $ 20,544 $ 32,378 $ 25,237 Ceded — — (22) (164) (311) (363) Net $ 13,441 $ 19,889 $ 18,512 $ 20,380 $ 32,067 $ 24,874 Total Gross $ 551,983 $ 729,918 $ 658,653 $ 949,530 $ 817,532 $ 862,113 Ceded (119,159) (157,826) (113,600) (145,483) (163,185) (166,334) Net $ 432,824 $ 572,092 $ 545,053 $ 804,047 $ 654,347 $ 695,779

Deferred Charge Assets and Defe

Deferred Charge Assets and Deferred Gain Liabilities	12 Months Ended
	Dec. 31, 2020
Insurance [Abstract]
Deferred Charge Assets and Deferred Gain Liabilities	9. DEFERRED CHARGE ASSETS AND DEFERRED GAIN LIABILITIES Deferred charge assets and deferred gain liabilities relate to retroactive reinsurance policies providing indemnification of losses and LAE with respect to past loss events in the Non-life Run-off segment. For (re)insurance contracts for which we do not elect the fair value option, a deferred charge asset is recorded for the excess, if any, of the estimated ultimate losses payable over the premiums received at the initial measurement; whereas, a deferred gain liability is recorded for the excess, if any, of the premiums received over the estimated ultimate losses payable at the initial measurement. In addition, for retrocessions of losses and LAE reserves that we have assumed through retroactive reinsurance contracts where the retroceded liabilities exceed the retrocession premiums paid, we record the excess as a deferred gain liability which is amortized to earnings over the estimated period during which the losses paid on the assumed retroceded liabilities are recovered from the retrocessionaire. For further information on our deferred charge assets and deferred gain liabilities, refer to Note 2 - "Significant Accounting Policies." Deferred Charge Assets Deferred charge assets are included in other assets on our consolidated balance sheets. The following table presents a reconciliation of the deferred charge assets for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Beginning carrying value $ 272,462 $ 86,585 $ 80,192 Recorded during the year 11,746 224,504 20,174 Amortization (45,606) (38,627) (13,781) Ending carrying value $ 238,602 $ 272,462 $ 86,585 Deferred charge assets are assessed at each reporting period for impairment. If the asset is determined to be impaired, it is written down in the period in which the determination is made. For the year ended December 31, 2020, we completed our assessment for impairment of deferred charge assets and concluded that there had been no impairment of our carried deferred charge asset balances. Further information on deferred charges recorded during the years ended December 31, 2020, 2019 and 2018 is included in Note 4 - "Significant New Business." Deferred Gain Liabilities Deferred gain liabilities are included in other liabilities on our consolidated balance sheets. The following table presents a reconciliation of the deferred gain liabilities for the years ended December 31, 2020 and 2019: 2020 2019 Beginning carrying value $ 12,875 $ — Recorded during the year 9,365 13,758 Amortization (2,360) (883) Ending carrying value $ 19,880 $ 12,875

Losses and Loss Adjustment Expe

Losses and Loss Adjustment Expenses	12 Months Ended
	Dec. 31, 2020
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 (classified as held-for-sale as of December 31, 2020) and StarStone segments using a variety of actuarial methods. We recognize an asset for the portion of the liability that we expect to recover from reinsurers. LAE reserves include allocated loss adjustment expenses ("ALAE"), and unallocated loss adjustment expenses ("ULAE"). ALAE are linked to the settlement of an individual claim or loss, whereas ULAE are based on our estimates of future costs to administer the claims. IBNR represents reserves for loss and LAE that have been incurred but not yet reported to us. This includes amounts for unreported claims, development on known claims and reopened claims. Our loss reserves cover multiple lines of business, including asbestos, environmental, general casualty, workers' compensation/personal accident, marine, aviation and transit, construction defect, professional indemnity/directors and officers, motor, property and other non-life lines of business. The following tables summarize the liability for losses and LAE by segment and for our other activities. 2020 Non-life StarStone Other Total Outstanding losses $ 4,440,425 $ 677,220 $ 10,204 $ 5,127,849 IBNR 4,641,500 615,963 20,040 5,277,503 Fair value adjustments - acquired companies (142,854) (329) — (143,183) Fair value adjustments - fair value option (54,589) — — (54,589) ULAE 350,600 35,102 — 385,702 Total $ 9,235,082 $ 1,327,956 $ 30,244 $ 10,593,282 Reconciliation to Consolidated Balance Sheet: Loss and loss adjustment expenses $ 6,782,162 $ 1,327,956 $ 30,244 $ 8,140,362 Loss and loss adjustment expenses, at fair value 2,452,920 — — 2,452,920 Total $ 9,235,082 $ 1,327,956 $ 30,244 $ 10,593,282 2019 Non-life Atrium StarStone Other Total Outstanding losses $ 4,407,082 $ 89,141 $ 743,830 $ 9,512 $ 5,249,565 IBNR 3,945,407 136,543 556,134 13,565 4,651,649 Fair value adjustments- acquired companies (170,689) 3,700 (522) — (167,511) Fair value adjustments - fair value option (217,933) — — — (217,933) ULAE 331,494 2,288 18,852 — 352,634 Total $ 8,295,361 $ 231,672 $ 1,318,294 $ 23,077 $ 9,868,404 Reconciliation to Consolidated Balance Sheet: Loss and loss adjustment expenses $ 5,674,239 $ 231,672 $ 1,318,294 $ 23,077 $ 7,247,282 Loss and loss adjustment expenses, at fair value 2,621,122 — — — 2,621,122 Total $ 8,295,361 $ 231,672 $ 1,318,294 $ 23,077 $ 9,868,404 The overall increase in the liability for losses and LAE between December 31, 2019 and December 31, 2020 was primarily attributable to the reinsurance transactions completed in 2020, as described in Note 4 - "Significant New Business," net incurred losses and LAE and foreign exchange losses in the year, partially offset by losses paid in the year. The table below provides a consolidated reconciliation of the beginning and ending liability for losses and LAE. 2020 2019 2018 Balance as of January 1 $ 9,868,404 $ 9,048,796 $ 7,100,488 Less: reinsurance reserves recoverable 1,927,624 1,708,272 1,693,028 Less: net deferred charge assets and gain liabilities on retroactive reinsurance 259,587 86,585 80,192 Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances (1) 643 — — Net balance as of January 1 7,680,550 7,253,939 5,327,268 Net incurred losses and LAE: Current period 405,178 580,074 533,081 Prior periods 10,748 34,105 (209,359) Total net incurred losses and LAE 415,926 614,179 323,722 Net paid losses: Current period (71,989) (179,461) (176,172) Prior periods (1,413,500) (1,609,009) (1,158,614) Total net paid losses (1,485,489) (1,788,470) (1,334,786) Effect of exchange rate movement 119,663 47,812 (145,243) Acquired on purchase of subsidiaries — 686 1,310,874 Assumed business 2,186,024 1,586,307 1,772,104 Ceded business (154,926) (33,260) — Reclassification to assets and liabilities held-for-sale (216,808) — — Net balance as of December 31 8,544,940 7,681,193 7,253,939 Plus: reinsurance reserves recoverable (2) 1,829,620 1,927,624 1,708,272 Plus: net deferred charge assets and gain liabilities on retroactive reinsurance 218,722 259,587 86,585 Balance as of December 31 $ 10,593,282 $ 9,868,404 $ 9,048,796 (1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details. This amount excludes $0.4 million related to the adoption impact of ASU 2016-13 on StarStone U.S., which has been classified as a discontinued operation with the related assets and liabilities disclosed as held-for-sale on our consolidated balance sheets. (2) Net of allowance for estimated uncollectible reinsurance. The tables below provide the components of net incurred losses and LAE by segment and for our other activities. 2020 Non-life Atrium StarStone Other Total Net losses paid $ 1,074,901 $ 73,920 $ 326,868 $ 9,800 $ 1,485,489 Net change in case and LAE reserves (1) (453,080) 7,245 (95,044) 692 (540,187) Net change in IBNR reserves (2) (718,414) 6,661 17,654 6,475 (687,624) Increase (reduction) in estimates of net ultimate losses (96,593) 87,826 249,478 16,967 257,678 Increase (reduction) in provisions for unallocated LAE (3) (48,765) (29) 17,244 — (31,550) Amortization of deferred charge assets and deferred gain liabilities (4) 42,640 — 606 — 43,246 Amortization of fair value adjustments (5) 28,667 (571) (590) — 27,506 Changes in fair value - fair value option (6) 119,046 — — — 119,046 Net incurred losses and LAE $ 44,995 $ 87,226 $ 266,738 $ 16,967 $ 415,926 2019 Non-life Atrium StarStone Other Total Net losses paid $ 1,247,624 $ 78,189 $ 450,835 $ 11,822 $ 1,788,470 Net change in case and LAE reserves (1) (530,891) 3,534 (4,686) 3,460 (528,583) Net change in IBNR reserves (2) (812,699) (4,782) 22,021 756 (794,704) Increase (reduction) in estimates of net ultimate losses (95,966) 76,941 468,170 16,038 465,183 Increase (reduction) in provisions for unallocated LAE (3) (57,404) — 902 — (56,502) Amortization of deferred charge assets and deferred gain liabilities (4) 37,744 — — — 37,744 Amortization of fair value adjustments (5) 50,070 335 168 — 50,573 Changes in fair value - fair value option (6) 117,181 — — — 117,181 Net incurred losses and LAE $ 51,625 $ 77,276 $ 469,240 $ 16,038 $ 614,179 2018 Non-life Atrium StarStone Other Total Net losses paid $ 838,817 $ 64,506 $ 427,371 $ 4,092 $ 1,334,786 Net change in case and LAE reserves (1) (547,420) 6,331 63,861 4,808 (472,420) Net change in IBNR reserves (2) (565,385) 4,091 46,501 7,999 (506,794) Increase (reduction) in estimates of net ultimate losses (273,988) 74,928 537,733 16,899 355,572 Increase (reduction) in provisions for unallocated LAE (3) (65,401) — 5,613 — (59,788) Amortization of deferred charge assets and deferred gain liabilities (4) 13,781 — — — 13,781 Amortization of fair value adjustments (5) 12,877 (5,118) (266) — 7,493 Changes in fair value - fair value option (6) 6,664 — — — 6,664 Net incurred losses and LAE $ (306,067) $ 69,810 $ 543,080 $ 16,899 $ 323,722 (1) Comprises the movement during the year in specific case reserve liabilities as a result of claims settlements or changes advised to us by our policyholders and attorneys, less changes in case reserves recoverable advised by us to our reinsurers as a result of the settlement or movement of assumed claims. (2) Represents the gross change in our actuarial estimates of IBNR, less amounts recoverable. (3) Represents the change in the estimate of the total future costs to administer the claims. (4) Relates to the amortization of deferred charge assets and deferred gain liabilities on retroactive reinsurance contracts. (5) Relates to the amortization of fair value adjustments associated with the acquisition of companies. . (6) Represents the changes in the fair value of liabilities related to our assumed retroactive reinsurance agreements for which we have elected the fair value option. Methodology for Establishing Reserves The liability for losses and LAE includes an amount determined from reported claims and an amount based on historical loss experience and industry statistics for IBNR using a variety of actuarial methods. Our loss reserves cover multiple lines of business, including workers' compensation, general casualty, asbestos and environmental, marine, aviation and transit, construction defects and other non-life lines of business. Our management, through our loss reserving committees, considers the reasonableness of loss reserves recommended by our actuaries, including actual loss development during the year. Case reserves are recognized for known claims (including the cost of related litigation) when sufficient information has been reported to us to indicate the involvement of a specific insurance policy. We use considerable judgment in estimating losses for reported claims on an individual claim basis based upon our knowledge of the circumstances surrounding the claim, the severity of the injury or damage, the jurisdiction of the occurrence, the potential for ultimate exposure, the type of loss, and our experience with the line of business and policy provisions relating to the particular type of claim. The reserves for unpaid reported losses and LAE are established by management based on reports from brokers, ceding companies and insureds and represent the estimated ultimate cost of events or conditions that have been reported to, or specifically identified, by us. We also consider facts currently known and the current state of the law and coverage litigation. IBNR reserves are established by management based on actuarially determined estimates of ultimate losses and loss expenses. We use generally accepted actuarial methodologies to estimate ultimate losses and LAE and those estimates are reviewed by management. In addition, the routine settlement of claims, at either below or above the carried advised loss reserve, updates historical loss development information to which actuarial methodologies are applied, often resulting in revised estimates of ultimate liabilities. On an annual basis, independent actuarial firms are retained by management to provide their estimates of ultimate losses and to review the estimates developed by our actuaries. Within the annual loss reserve studies produced by either our actuaries or independent actuaries, exposures for each subsidiary are separated into homogeneous reserving categories for the purpose of estimating IBNR. Each reserving category contains either direct insurance or assumed reinsurance reserves and groups relatively similar types of risks and exposures (for example, asbestos, environmental, casualty, property) and lines of business written (for example, marine, aviation, non-marine). Based on the exposure characteristics and the nature of available data for each individual reserving category, a number of methodologies are applied. Recorded reserves for each category are selected from the actuarial indications produced by the various methodologies after consideration of exposure characteristics, data limitations and strengths and weaknesses of each method applied. This approach to estimating IBNR has been consistently adopted in the annual loss reserve studies for each period presented. The estimation of unpaid claim liabilities at any given point in time is subject to a high degree of uncertainty for a number of reasons. A significant amount of time can lapse between the assumption of risk, the occurrence of a loss event, the reporting of the event to an insurance or reinsurance company and the ultimate payment of the claim on the loss event. Our actuarial methodologies include amongst other methodologies industry benchmarking which, under certain actuarial methods, compares the trend of our loss development to that of the industry. To the extent that the trend of our loss development compared to the industry changes in any period, it is likely to have an impact on our estimate of ultimate liabilities. Unpaid claim liabilities for property and casualty exposures in general are impacted by changes in the legal environment, jury awards, medical cost trends and general inflation. Certain estimates for unpaid claim liabilities involve considerable uncertainty due to significant coverage litigation, and it can be unclear whether past claim experience will be representative of future claim experience. Ultimate values for such claims cannot be estimated using reserving techniques that extrapolate losses to an ultimate basis using loss development factors, and the uncertainties surrounding the estimation of unpaid claim liabilities are not likely to be resolved in the near future. In addition, reserves are established to cover loss development related to both known and unasserted claims. Consequently, our subsequent estimates of ultimate losses and LAE, and our liability for losses and LAE, may differ materially from the amounts recorded in our consolidated financial statements. Asbestos and Environmental In establishing the reserves for losses and LAE related to asbestos and environmental claims, management considers facts currently known and the current state of the law and coverage litigation environment. Liabilities are recognized for known claims (including the cost of related litigation) when sufficient information has been developed to indicate the involvement of a specific insurance policy, and management can reasonably estimate its liability. In addition, reserves have been established to cover additional exposures on both known and unreported claims. Estimates of the reserves are reviewed and updated continually. Developed case law and claim histories are still evolving for such claims, especially because significant uncertainty exists about the outcome of coverage litigation and whether past claim experience will be representative of future claim experience. In view of the changes in the legal and tort environment that affect the development of such claims, the uncertainties inherent in valuing asbestos and environmental claims are not likely to be resolved in the near future. Ultimate values for such claims cannot be estimated using traditional reserving techniques and there are significant uncertainties in estimating the amount of our potential losses for these claims. There can be no assurance that the reserves established by us will be adequate or will not be adversely affected by the development of other latent exposures. The net liability for unpaid losses and LAE as of December 31, 2020 and 2019 included $1.9 billion and $2.1 billion, respectively, which represented an estimate of the net ultimate liability for asbestos and environmental claims. The gross liability for such claims as of December 31, 2020 and 2019 was $2.1 billion and $2.3 billion, respectively. For the years ended December 31, 2020 and 2019, our reserves for asbestos and environmental liabilities decreased by $178.2 million and increased by $419.9 million on a gross basis, respectively, and decreased by $227.2 million and increased by $374.7 million on a net basis, respectively. The decrease in 2020 was primarily due to net paid losses while the increase in 2019 was primarily due to acquisition activity, partially offset by net paid losses. Disclosures of Incurred and Paid Loss Development, IBNR, Claims Counts and Payout Percentages The loss development tables disclosed below, sets forth our historic incurred and paid loss development by accident year through December 31, 2020, net of reinsurance, as well as the cumulative number of reported claims, IBNR balances, and other supplementary information. The loss development tables disclosed below are presented as follows: • Non-Life Run-off - Loss development disclosures have been provided for the 10 latest acquisition years, in addition to disclosures for lines of business with material net losses and LAE reserve balances as of December 31, 2020, within those 10 latest acquisition years, also being provided. The disaggregated lines of business include general casualty, workers’ compensation, motor and professional indemnity and directors and officers. • StarStone Incurred and Paid Loss Development and IBNR Disclosures For each acquisition year and/or line of business for which incurred losses and allocated loss adjustment expenses, net of reinsurance tables have been provided below, the disclosure approach and format adopted reflects the following: • The incurred loss development tables include both reported case reserves and IBNR liabilities, as well as cumulative paid losses; • Both the incurred and cumulative paid loss development tables include allocated LAE (i.e. claims handling costs allocated to specific individual claims) but exclude unallocated LAE (i.e. the costs associated with internal claims staff and third party administrators as well as consultants that cannot be allocated to specific individual claims); • The fair value adjustments related to business acquisitions are excluded from the loss development tables, however the undiscounted incurred losses, cumulative paid losses and allocated LAE related to business acquisitions are included in the loss development tables; • The fair value adjustments related to retroactive reinsurance agreements for which we have elected the fair value option are excluded from the loss development tables, however the undiscounted incurred losses, cumulative paid losses and allocated LAE related to retroactive reinsurance agreements for which we have elected the fair value option are included in the loss development tables; • The amounts relating to the amortization of deferred charge assets and deferred gain liabilities are excluded from the loss development tables; • In the incurred loss development tables, the incurred effect of agreeing a commutation or policy buyback is included in the period in which the commutation or policy buyback is contractually agreed. We reflect the net incurred loss development arising from a commutation or policy buyback in the fiscal year in which a commutation or policy buyback is contractually agreed, and the net incurred loss development is allocated to the appropriate accident year. The claim will generally have been adjusted throughout its lifetime and the amounts recorded in prior years (which is considered supplementary information) remain unchanged in our loss development tables, such that the incurred amount that we recognize in the year in which a commutation or policy buyback is contractually agreed represents the effect of the commutation or policy buyback settlement compared to the carried net loss and LAE reserve balance in the prior year. We do not recast prior years to remove commuted or bought back claims, since this practice would eliminate any historical favorable or adverse development we may have experienced on the commuted loss and LAE reserves. Reserves that have been commuted or bought back are not adjusted in future years but the commuted or bought back value remains in our total incurred losses; • In the cumulative paid losses tables, we reflect the amount of the commutation or policy buyback settlements in the year in which they are actually paid or received, and the net payment is allocated to the appropriate accident year. The claim or recoverable may have recorded payments or receipts throughout its lifetime and amounts recorded in prior years (which is considered supplementary information) remain unchanged in our loss development tables, such that the amounts paid or received that we recognize in the year in which a commutation or policy buyback is paid or received represents the amount actually paid or received. We do not recast prior years to remove payments or receipts related to commutations or policy buybacks, since we consider commutations and policy buybacks a key component of our business and are reflective of our ability to effectively manage acquired losses and LAE liabilities. Payments relating to commutations and policy buybacks are not adjusted in future years but the payments remain in our total cumulative paid losses; • The amounts included within the loss development tables for the years ended December 31, 2011 through to December 31, 2019 (and in the case of StarStone, from April 1, 2014 its acquisition date through to December 31, 2019), as well as the historical average annual percentage payout ratios as of December 31, 2020, are presented as supplementary information and are therefore unaudited; • All data presented within the loss development tables is net of reinsurance recoveries, excluding provisions for uncollectible reinsurance recoverables; • All the incurred and paid loss activity presented within the loss development tables provided below, exclude intercompany cessions. Upon the sale of StarStone U.S. to Core Specialty on November 30, 2020, the incurred and paid loss development activity related to the cessions from StarStone U.S. to our other subsidiaries were no longer eliminated on consolidation and have been included within the loss development tables presented below; • The IBNR reserves included within each incurred loss development table by accident year, reflect the net IBNR recorded as of December 31, 2020, including expected development on reported losses; • For the Non-life Run-off segment loss development tables, all information for both acquisitions and retroactive reinsurance agreements is presented prospectively. As the loss reserves are effectively re-underwritten at the date that they are acquired or assumed, we believe that the historical loss development prior to their acquisition is not relevant with respect to our own experience managing these acquired loss reserves. In addition, the information required to prepare the loss development disclosures on a retrospective basis is not always available to us and a mixed presentation approach would result in loss development tables that are not entirely reflective of the actual loss development of the acquired loss reserves; • For the Non-life Run-off segment we have also presented the net incurred and paid losses and ALAE information by calendar year as well as IBNR and claim counts for accident years older than 10 years on a single row within the loss development tables. This presentation differs from the typical approach where only the net outstanding losses and LAE reserves are presented as a reconciling item at the bottom of the loss development tables. The additional detailed disclosures are provided on a voluntary basis and the inclusion of the disclosures is to provide additional information to the users of our financial statements and to also enable the reconciliation of our total loss reserves by acquisition year and by significant line of business; • For the StarStone segment loss development tables, all information has been presented on a prospective basis from the date of our acquisition of StarStone, which was effective on April 1, 2014. Providing pre-acquisition incurred and paid losses by accident year for years prior to 2014 was determined to be impracticable due to significant data limitations; and • Following our sale of StarStone U.S. to Core Specialty which was completed on November 30, 2020, the loss development disclosures presented below for all the individual lines of business within the StarStone segment have been restated to exclude the historical incurred and paid loss development related to StarStone U.S. The historical amounts disclosed within the loss development tables for all the acquisition years and lines of business presented below are on a constant-currency basis, which is achieved by using constant foreign exchange rates between periods in the loss development tables, and translating prior period amounts denominated in currencies other than the U.S. dollar, which is our reporting currency, using the closing exchange rates as of December 31, 2020. The impact of this exchange rate conversion is to show the change between periods exclusive of the effect of exchange rate fluctuations, which would otherwise distort the change in incurred losses and the cash flow patterns associated with those incurred losses shown within the loss development tables. The change in net incurred losses shown within the loss development tables will, however, differ from other U.S. GAAP disclosures of incurred current and prior period reserve development amounts, which include the effect of exchange rate fluctuations. Establishing an estimate for loss reserves involves various assumptions and judgments, therefore, the information contained within the loss development disclosures only allows readers or users of our consolidated financial statements to understand, at the summary level presented in the development tables, the change over time in our reported incurred loss estimates as well as the nature and patterns of the cash flows associated with those estimates. We, therefore, believe that the information provided within the loss development tables disclosed below is of limited use for independent analysis or application of standard actuarial estimations, and any results obtained from doing so should be interpreted with caution. Cumulative Number of Reported Claims Reported claim counts, on a cumulative basis, are provided as supplemental information to each incurred loss development table by accident year. We measure claim frequency information on an individual claim count basis within each of our segments as follows: • Non-Life Run-off - The claim frequency information for the exposures included within our Non-life Run-off lines of business includes direct and assumed open and closed claims by accident year at the claimant level. Reported claims that are closed without a payment are included within our cumulative number of reported claims because we typically incur claim adjustment expenses on them prior to their closure. The claim count numbers exclude counts related to claims within policy deductibles where the insured is responsible for the payment of losses within the deductible layer. Individual claim counts related to certain assumed reinsurance contracts such as excess-of-loss and quota share treaties are not available to us, and the losses arising from these treaties have been treated as single claims for the purposes of determining claim counts. Therefore, each treaty year within the reinsurance contract is deemed a single claim because the detailed underlying individual claim information is generally not reported to us by our cedants; and • StarStone - The claim frequency information is determined at the claimant level for the exposures within the lines of business related to these segments. Our claims system assigns a unique claim identifier to each reported claim we receive. Each unique claim identifier is deemed to be a single claim, irrespective of whether the claim remains open or has been closed with or without payment. For certain insurance facilities and business produced or managed by managing general agents, coverholders and third party administrators where the underlying claims data is reported to us in an aggregated format, the information necessary to provide cumulative claims frequency is not available. In such cases, we typically record a “block” claim in our system. This also applies to a small amount of assumed reinsurance business that we write where, similarly, the underlying claims data is reported to us in an aggregated format. In such instances, each assumed reinsurance contract is deemed a single claim. Our reported claim frequency information is subject to the following inherent limitations when analyzing our loss experience and severity: • Claim counts are presented only on a reported and not on an ultimate basis. Therefore, reported claim counts include open claims which have outstanding reserves but exclude IBNR claims. As such the reported claims are consistent with reported losses, which can be calculated by subtracting IBNR losses from incurred losses. However, the reported claim counts are inconsistent with the losses in the incurred loss development tables, which include IBNR losses, and to losses in the paid loss development tables, which exclude outstanding reserves; • Reported claim counts have not been adjusted for ceded reinsurance, which may distort any measures of frequency or severity; • For lines of business that have a mix of primary and excess layer exposures, such as our general casualty and workers’ compensation lines of business, the reported claim counts may fluctuate from period to period between exposure layers, thereby distorting any measure of frequency and severity; and • The use of our reported claim frequency information to project ultimate loss payouts by disaggregated disclosure category or line of business may not be as meaningful as claim count information related to individual contracts at a more granular level. Payout Percentages • Non-life Run-off - The annual percentage payout disclosures for our Non-life Run-off segment are based on the payout of incurred claims by age, net of reinsurance. For our Non-life Run-off segment, claims aging reflects the number of years that have lapsed since the original acquisition of the related net liability for losses and LAE reserves to the date the claim is paid. There may be occasions where, due to our claims management strategies (including commutations and policy buy-backs) or due to the timing of claims payments relative to the associated recovery, the cash received from reinsurance recoveries is greater than the cash paid out to our claimants, (i.e. a net recovery rather than a net payout for a particular calendar year), thereby resulting in a negative annual percentage payout for that calendar year. • StarStone - The average annual percentage payout disclosures for our StarStone segment are based on the payout of incurred claims by age, net of reinsurance. The table below provides a reconciliation of the beginning and ending reserves for losses and LAE for the Non-life Run-off segment. 2020 2019 2018 Balance as of January 1 $ 8,295,361 $ 7,540,662 $ 5,949,472 Less: reinsurance reserves recoverable 1,543,614 1,366,123 1,377,485 Less: net deferred charge assets and gain liabilities on retroactive reinsurance 259,587 86,585 80,192 Plus: cumulative effect of change in accounting principal on allowance for estimated uncollectible reinsurance (1) 703 — — Net balance as of January 1 6,492,863 6,087,954 4,491,795 Net incurred losses and LAE: Current period 30,165 123,559 12,451 Prior periods 14,830 (71,934) (318,518) Total net incurred losses and LAE 44,995 51,625 (306,067) Net paid losses: Current period (9,990) (64,820) (5) Prior periods (1,064,911) (1,182,804) (838,812) Total net paid losses (1,074,901) (1,247,624) (838,817) Effect of exchange rate movement 94,745 46,472 (132,632) Acquired on purchase of subsidiaries — 686 1,111,839 Assumed business 2,186,024 1,586,307 1,761,836 Ceded business (154,926) (33,260) — Net balance as of December 31 7,588,800 6,492,160 6,087,954 Plus: reinsurance reserves recoverable (2) 1,427,560 1,543,614 1,366,123 Plus: net deferred charge assets and gain liabilities on retroactive reinsurance 218,722 259,587 86,585 Balance as of December 31 $ 9,235,082 $ 8,295,361 $ 7,540,662 (1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details. (2) Net of allowance for estimated uncollectible reinsurance. Net incurred losses and LAE in the Non-life Run-off segment were as follows: 2020 2019 2018 Prior Current Total Prior Current Total Prior Current Total Net losses paid $ 1,064,911 $ 9,990 $ 1,074,901 $ 1,182,804 $ 64,820 $ 1,247,624 $ 838,812 $ 5 $ 838,817 Net change in case and LAE reserves (1) (449,610) (3,470) (453,080) (553,996) 23,105 (530,891) (552,124) 4,704 (547,420) Net change in IBNR reserves (2) (742,417) 24,003 (718,414) (847,893) 35,194 (812,699) (573,127) 7,742 (565,385) Increase (reduction) in estimates of net ultimate losses (127,116) 30,523 (96,593) (219,085) 123,119 (95,966) (286,439) 12,451 (273,988) Increase (reduction) in provisions for unallocated LAE (3) (48,407) (358) (48,765) (57,844) 440 (57,404) (65,401) — (65,401) Amortization of deferred charge assets and deferred gain liabilities (4) 42,640 — 42,640 37,744 — 37,744 13,781 — 13,781 Amortization of fair value adjustments (5) 28,667 — 28,667 50,070 — 5

Defendant Asbestos and Environm

Defendant Asbestos and Environmental Liabilities	12 Months Ended
	Dec. 31, 2020
Liability for Asbestos and Environmental Claims [Abstract]
DEFENDANT ASBESTOS AND ENVIRONMENTAL LIABILITIES	11. DEFENDANT ASBESTOS AND ENVIRONMENTAL LIABILITIES We acquired DCo LLC ("DCo") on December 30, 2016, and Morse TEC on October 30, 2019. These companies hold liabilities associated with personal injury asbestos claims and environmental claims arising from their legacy manufacturing operations. Defendant asbestos liabilities on our consolidated balance sheets include amounts for loss payments and defense costs for pending and future asbestos-related claims, determined using standard actuarial techniques for asbestos exposures. Defendant environmental liabilities include estimated clean-up costs associated with the acquired companies' former operations based on engineering reports. Insurance balances recoverable on our consolidated balance sheets include estimated insurance recoveries relating to these liabilities. The recorded asset represents our assessment of the capacity of the insurance agreements to indemnify our subsidiaries for the anticipated defense and loss payments for pending claims and projected future claims. The recognition of these recoveries is based on an assessment of the right to recover under the respective contracts and on the financial strength of the insurers. The recorded asset does not represent the limits of our insurance coverage, but rather the amount we would expect to recover if the accrued and projected loss and defense costs were paid in full. Included within insurance balances recoverable and defendant asbestos and environmental liabilities are the fair value adjustments that were initially recognized upon acquisition. These fair value adjustments are amortized in proportion to the actual payout of claims and recoveries. The carrying value of the asbestos and environmental liabilities, insurance recoveries, future estimated expenses and the fair value adjustments related to DCo and Morse TEC as of December 31, 2020 and 2019 was as follows: 2020 2019 Defendant asbestos and environmental liabilities: Defendant asbestos liabilities $ 913,276 $ 1,100,593 Defendant environmental liabilities 12,572 10,279 Estimated future expenses 42,510 51,637 Fair value adjustments (262,029) (314,824) Defendant asbestos and environmental liabilities 706,329 847,685 Insurance balances recoverable: Insurance recoveries related to defendant asbestos liabilities (net of allowance: 2020 - $4,824) 310,602 549,593 Fair value adjustments (60,950) (100,738) Insurance balances recoverable 249,652 448,855 Net liabilities relating to defendant asbestos and environmental exposures $ 456,677 $ 398,830 The table below provides a consolidated reconciliation of the beginning and ending liability for defendant asbestos and environmental exposures for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Balance as of January 1 847,685 203,320 219,164 Less: Insurance balances recoverable 448,855 135,808 122,326 Plus: Cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible insurance balances (1) 3,167 — — Net balance as of January 1 401,997 67,512 96,838 Total net recoveries (paid claims) 153,964 (10,434) (6,351) Amounts recorded in other income (expense): Change in estimate of net ultimate liabilities (103,166) (4,263) (23,221) Reduction in estimated future expenses (9,126) (3,274) — Amortization of fair value adjustments 13,008 13,500 246 Total other expense (income) (99,284) 5,963 (22,975) Acquired on purchase of subsidiaries — 335,789 — Net balance as of December 31 456,677 398,830 67,512 Plus: Insurance balances recoverable (2) 249,652 448,855 135,808 Balance as of December 31 706,329 847,685 203,320 (1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 1 - "Significant Accounting Policies" for further details. (2) Net of allowance for estimated uncollectible insurance balances. Total other income from our defendant asbestos and environmental liabilities companies was $99.3 million for the year ended December 31, 2020 and was driven by a reduction in the actuarially estimated ultimate net liabilities as a result of a lower than expected number of asbestos claims filed against us; lower than expected paid indemnity and defense costs; the collection of disputed insurance recoveries that were carried on our balance sheet at $166.7 million, net of fair value adjustments, for consideration of $179.6 million; and recovery of $19.3 million on insurance payments previously written-off prior to our acquisition of the companies. Methodologies for determining liabilities Defendant Asbestos Liabilities We review, on an ongoing basis, our own experience in handling asbestos-related claims and trends affecting asbestos-related claims in the U.S. tort system generally, for the purposes of assessing the value of pending asbestos-related claims and the number and value of those that may be asserted in the future, as well as potential recoveries from our insurance carriers with respect to such claims and defense costs. The actuarial analysis for these asbestos-related exposures utilizes data resulting from the claim review process, including input from national coordinating counsel and local counsel, and includes the development of an estimate of the potential value of asbestos-related claims asserted but not yet resolved as well as the number and potential value of asbestos-related claims not yet asserted. In developing the estimate of liability for potential future claims, the actuarial analysis projects the potential number of future claims based on our historical claim filings and epidemiological studies. The actuarial analysis also utilizes assumptions based on our historical proportion of claims resolved without payment, historical claim resolution costs for those claims that result in a payment, and historical defense costs. The liabilities are then estimated by multiplying the pending and projected future claim filings by projected payments rates and average claim resolution amounts and then adding an estimate for defense costs. We determine, based on the factors described above, including the actuarial analysis, that their best estimate of the aggregate liability both for asbestos-related claims asserted but not yet resolved and potential asbestos-related claims not yet asserted, including estimated defense costs, was $913.3 million and $1.1 billion as of December 31, 2020 and 2019, respectively. Defendant Environmental Liabilities As a result of our acquisition of DCo and Morse TEC, we have been identified by the United States Environmental Protection Agency and certain U.S. state environmental agencies and private parties as potentially responsible parties ("PRP") at various hazardous waste disposal sites under the Comprehensive Environmental Allowance for Estimated Uncollectible Insurance Balances Recoverable on Defendant Asbestos Liabilities We evaluate and monitor the credit risk related to our insurers and an allowance for estimated uncollectible insurance balances recoverable on our defendant asbestos liabilities ("allowance for estimated uncollectible insurance") is established for amounts considered potentially uncollectible. To determine the allowance for estimated uncollectible insurance, we use the inputs and methodologies as described in Note 8 - "Reinsurance Balances Recoverable on Paid and Unpaid Losses" above. The table below provides a reconciliation of the beginning and ending allowance for estimated uncollectible insurance balances related to our defendant asbestos liabilities, for the years ended December 31, 2020 and 2019: 2020 2019 Allowance for estimated uncollectible insurance balances, beginning of year $ 3,818 $ — Cumulative effect of change in accounting principle 3,167 — Current period change in the allowance (2,161) 3,818 Allowance for estimated uncollectible insurance balances, end of year $ 4,824 $ 3,818 During the year ended December 31, 2020, we did not have any write-offs charged against the allowance for estimated uncollectible insurance or any recoveries of amounts previously written off.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	12. FAIR VALUE MEASUREMENTS Fair Value Hierarchy Fair value is defined as the price at which to sell an asset or transfer a liability (i.e. the "exit price") in an orderly transaction between market participants. We use a fair value hierarchy that gives the highest priority to quoted prices in active markets and the lowest priority to unobservable data. The hierarchy is broken down into three levels as follows: • Level 1 - Valuations based on unadjusted quoted prices in active markets for identical assets or liabilities that we have the ability to access. Valuation adjustments and block discounts are not applied to Level 1 instruments. • Level 2 - Valuations based on quoted prices in active markets for similar assets or liabilities, quoted prices for identical assets or liabilities in inactive markets, or for which significant inputs are observable (e.g. interest rates, yield curves, prepayment speeds, default rates, loss severities, etc.) or can be corroborated by observable market data. • Level 3 - Valuations based on unobservable inputs where there is little or no market activity. Unadjusted third party pricing sources or management's assumptions and internal valuation models may be used to determine the fair values. In addition, certain of our other investments are measured at fair value using net asset value ("NAV") per share (or its equivalent) as a practical expedient and have not been classified within the fair value hierarchy above. We have categorized our assets and liabilities that are recorded at fair value on a recurring basis among levels based on the observability of inputs, or at fair value using NAV per share (or its equivalent) as follows: December 31, 2020 Quoted Prices in Significant Significant Fair Value Based on NAV as Practical Expedient Total Fair Investments: Short-term and Fixed maturity investments: U.S. government and agency $ — $ 951,048 $ — $ — $ 951,048 U.K. government — 51,082 — — 51,082 Other government — 502,153 — — 502,153 Corporate — 5,686,732 — — 5,686,732 Municipal — 162,669 — — 162,669 Residential mortgage-backed — 553,945 — — 553,945 Commercial mortgage-backed — 854,090 — — 854,090 Asset-backed — 557,460 — — 557,460 $ — $ 9,319,179 $ — $ — $ 9,319,179 Other assets included within funds held - directly managed — 14,627 — — 14,627 Equities: Publicly traded equity investments $ 229,167 $ 31,600 $ — $ — $ 260,767 Exchange-traded funds 311,287 — — — 311,287 Privately held equity investments — — 274,741 — 274,741 $ 540,454 $ 31,600 $ 274,741 $ — $ 846,795 Other investments: Hedge funds $ — $ — $ — $ 2,638,339 $ 2,638,339 Fixed income funds — 285,837 — 266,704 552,541 Equity funds — 5,073 — 185,694 190,767 Private equity funds — — — 363,103 363,103 CLO equities — 128,083 — — 128,083 CLO equity funds — — — 166,523 166,523 Private credit funds — — 9,250 183,069 192,319 Other — — 314 12,045 12,359 $ — $ 418,993 $ 9,564 $ 3,815,477 $ 4,244,034 Total Investments $ 540,454 $ 9,784,399 $ 284,305 $ 3,815,477 $ 14,424,635 Cash and cash equivalents $ 385,790 $ 208,272 $ — $ — $ 594,062 Reinsurance balances recoverable on paid and unpaid losses: $ — $ — $ 520,830 $ — $ 520,830 Other Assets: Derivatives qualifying as hedging $ — $ 1,169 $ — $ — $ 1,169 Derivatives not qualifying as hedges — 2,964 — — 2,964 Derivative instruments $ — $ 4,133 $ — $ — $ 4,133 Losses and LAE: $ — $ — $ 2,452,920 $ — $ 2,452,920 Other Liabilities: Derivatives qualifying as hedging $ — $ 28,947 $ — $ — $ 28,947 Derivatives not qualifying as hedges — 5,195 — — 5,195 Derivative instruments $ — $ 34,142 $ — $ — $ 34,142 December 31, 2019 Quoted Prices in Significant Significant Fair Value Based on NAV as Practical Expedient Total Fair Investments: Short-term and Fixed maturity investments: U.S. government and agency $ — $ 696,077 $ — $ — $ 696,077 U.K government — 161,772 — — 161,772 Other government — 702,856 — — 702,856 Corporate — 5,448,270 — — 5,448,270 Municipal — 140,687 — — 140,687 Residential mortgage-backed — 400,914 — — 400,914 Commercial mortgage-backed — 813,746 — — 813,746 Asset-backed — 670,235 — — 670,235 $ — $ 9,034,557 $ — $ — $ 9,034,557 Other assets included within funds held - directly managed $ — $ 14,207 $ — $ — $ 14,207 Equities: Publicly traded equity investments $ 297,310 $ 30,565 $ — $ — $ 327,875 Exchange-traded funds 133,047 — — — 133,047 Privately held equity investments — — 265,799 — 265,799 $ 430,357 $ 30,565 $ 265,799 $ — $ 726,721 Other investments: Hedge funds $ — $ — $ — $ 1,121,904 $ 1,121,904 Fixed income funds — 398,143 — 82,896 481,039 Equity funds — 111,040 — 299,109 410,149 Private equity funds — — — 323,496 323,496 CLO equities — — 87,555 — 87,555 CLO equity funds — — — 87,509 87,509 Other — 34 314 6,031 6,379 $ — $ 509,217 $ 87,869 $ 1,920,945 $ 2,518,031 Total Investments $ 430,357 $ 9,588,546 $ 353,668 $ 1,920,945 $ 12,293,516 Cash and cash equivalents $ 144,984 $ 222,191 $ — $ — $ 367,175 Reinsurance balances recoverable on paid and unpaid losses: $ — $ — $ 695,518 $ — $ 695,518 Other Assets: Derivatives qualifying as hedging $ — $ 642 $ — $ — $ 642 Derivatives not qualifying as hedges — 1,369 — — 1,369 Derivative instruments $ — $ 2,011 $ — $ — $ 2,011 Losses and LAE: $ — $ — $ 2,621,122 $ — $ 2,621,122 Other Liabilities: Derivatives qualifying as hedging $ — $ 11,452 $ — $ — $ 11,452 Derivatives not qualifying as hedges — 4,106 — — 4,106 Derivative instruments $ — $ 15,558 $ — $ — $ 15,558 Short-term and Fixed Maturity Investments The fair values for all securities in the short-term and fixed maturity investments and funds held - directly managed portfolios are independently provided by the investment accounting service providers, investment managers and investment custodians, each of which utilize internationally recognized independent pricing services. We record the unadjusted price provided by the investment accounting service providers, investment managers or investment custodians and validate this price through a process that includes, but is not limited to: (i) comparison of prices against alternative pricing sources; (ii) quantitative analysis (e.g. comparing the quarterly return for each managed portfolio to its target benchmark); (iii) evaluation of methodologies used by external parties to estimate fair value, including a review of the inputs used for pricing; and (iv) comparing the price to our knowledge of the current investment market. Our internal price validation procedures and review of fair value methodology documentation provided by independent pricing services have not historically resulted in adjustment in the prices obtained from the pricing service. The independent pricing services used by the investment accounting service providers, investment managers and investment custodians obtain actual transaction prices for securities that have quoted prices in active markets. Where we utilize single unadjusted broker-dealer quotes, they are generally provided by market makers or broker-dealers who are recognized as market participants in the markets for which they are providing the quotes. For determining the fair value of securities that are not actively traded, in general, pricing services use "matrix pricing" in which the independent pricing service uses observable market inputs including, but not limited to, reported trades, benchmark yields, broker-dealer quotes, interest rates, prepayment speeds, default rates and other such inputs as are available from market sources to determine a reasonable fair value. The following describes the techniques generally used to determine the fair value of our short-term and fixed maturity investments by asset class, including the investments underlying the funds held - directly managed. • U.S. government and agency securities consist of securities issued by the U.S. Treasury and mortgage pass-through agencies such as the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation and other agencies. Non-U.S. government securities consist of bonds issued by non-U.S. governments and agencies along with supranational organizations. The significant inputs used to determine the fair value of these securities include the spread above the risk-free yield curve, reported trades and broker-dealer quotes. These are considered to be observable market inputs and, therefore, the fair values of these securities are classified as Level 2. • Corporate securities consist primarily of investment-grade debt of a wide variety of corporate issuers and industries. The fair values of these securities are determined using the spread above the risk-free yield curve, reported trades, broker-dealer quotes, benchmark yields, and industry and market indicators. These are considered observable market inputs and, therefore, the fair values of these securities are classified as Level 2. Where pricing is unavailable from pricing services, such as in periods of low trading activity or when transactions are not orderly, we obtain non-binding quotes from broker-dealers. Where significant inputs are unable to be corroborated with market observable information, we classify the securities as Level 3. • Municipal securities consist primarily of bonds issued by U.S.-domiciled state and municipal entities. The fair values of these securities are determined using the spread above the risk-free yield curve, reported trades, broker-dealer quotes and benchmark yields. These are considered observable market inputs and, therefore, the fair values of these securities are classified as Level 2. • Asset-backed securities consist primarily of investment-grade bonds backed by pools of loans with a variety of underlying collateral. Residential and commercial mortgage-backed securities include both agency and non-agency originated securities. Where pricing is unavailable from pricing services, we obtain non-binding quotes from broker-dealers. This is generally the case when there is a low volume of trading activity and current transactions are not orderly. The significant inputs used to determine the fair value of these securities include the spread above the risk-free yield curve, reported trades, benchmark yields, prepayment speeds and default rates. The fair values of these securities are classified as Level 2 if the significant inputs are market observable. Where significant inputs are unable to be corroborated with market observable information, we classify the securities as Level 3. Equities Our investments in equities consist of a combination of publicly and privately traded investments. Our publicly traded equity investments in common and preferred stocks predominantly trade on major exchanges and are managed by our external advisors. Our exchange-traded funds also trade on major exchanges. Our publicly traded equities are widely diversified and there is no significant concentration in any specific industry. We use an internationally recognized pricing service to estimate the fair value of our publicly traded equities and exchange-traded funds. We have categorized the majority of our publicly traded equity investments, other than preferred stock, and our exchange-traded funds as Level 1 investments because the fair values of these investments are based on unadjusted quoted prices in active markets for identical assets. One equity security is trading in an inactive market and, as a result has been classified as Level 2. The fair value estimates of our investments in publicly traded preferred stock are based on observable market data and, as a result, have been categorized as Level 2. Other investments, at fair value We have ongoing due diligence processes with respect to the other investments carried at fair value in which we invest, including active discussions with managers of the investments. These processes are designed to assist us in assessing the quality of information provided by, or on behalf of, each fund and in determining whether such information continues to be reliable or whether further review is warranted. Certain funds do not provide full transparency of their underlying holdings; however, we obtain the audited financial statements for funds annually and review the audited results relative to the net asset values provided by the managers, and regularly review and discuss the fund performance with the fund managers to corroborate the reasonableness of the reported net asset values ("NAV"). The use of NAV as an estimate of the fair value for investments in certain entities that calculate NAV is a permitted practical expedient. Due to the time lag in the NAV reported by certain fund managers we adjust the valuation for capital calls and distributions. Other investments measured at fair value using NAV as a practical expedient have not been classified in the fair value hierarchy. Other investments for which we do not use NAV as a practical expedient have been valued using prices from independent pricing services, investment managers and broker-dealers. The following describes the techniques generally used to determine the fair value of our other investments. • For our investments in hedge funds, we measure fair value by obtaining the most recently available NAV as advised by the external fund manager or third-party administrator. The fair values of these investments are measured using the NAV as a practical expedient and therefore have not been categorized within the fair value hierarchy. • Our investments in fixed income funds and equity funds are valued based on a combination of prices from independent pricing services, external fund managers or third-party administrators. For the publicly available prices we have classified the investments as Level 2. For the non-publicly available prices we are using NAV as a practical expedient and therefore these have not been categorized within the fair value hierarchy. • For our investments in private equity funds, we measure fair value by obtaining the most recently available NAV from the external fund manager or third-party administrator. The fair values of these investments are measured using the NAV as a practical expedient and therefore have not been categorized within the fair value hierarchy. • We measure the fair value of our direct investment in CLO equities based on valuations provided by independent pricing services, our external CLO equity manager, and valuations provided by the broker or lead underwriter of the investment (the "broker"). The fair values measured using prices provided by independent pricing services have been classified as Level 2 and fair values using prices from brokers have been classified as Level 3 due to the use of unobservable inputs in the valuation and the limited number of relevant trades in secondary markets. • For our investments in the CLO equity funds, we measure fair value by obtaining the most recently available NAV as advised by the external fund manager or third party administrator. The fair value of these investments is measured using the NAV as a practical expedient and therefore have not been categorized within the fair value hierarchy. • Our investments in private credit funds are primarily valued by obtaining the most recently available NAV from the external fund manager or third-party administrator. The fair values of these investments are measured using the NAV as a practical expedient and therefore have not been categorized within the fair value hierarchy. Included within private credit funds is a loan which is valued at cost less distributions received to date. • Included within other is an investment in a real estate debt fund, for which we measure fair value by obtaining the most recently available NAV from the external fund manager or third-party administrator. The fair value of this investment is measured using the NAV as a practical expedient and therefore has not been categorized within the fair value hierarchy. Cash and Cash Equivalents Cash equivalents are short-term, highly liquid investments that are readily convertible to known amounts of cash and are very close to maturity that they present insignificant risk of changes in value due to changes in interest rates. Included within cash and cash equivalents are money market funds, fixed interest deposits and highly liquid fixed maturity investments purchased with an original maturity of three months or less. The majority of our cash and cash equivalents included within the fair value hierarchy are comprised of money market and liquid reserve funds which have been categorized as Level 1. Fixed interest deposits and highly liquid fixed maturity investments with an original maturity of three months or less have been categorized as Level 2. Operating cash balances are not subject to the recurring fair value measurement guidance and are therefore excluded from the fair value hierarchy. Insurance Contracts - Fair Value Option The Company uses an internal model to calculate the fair value of the liability for losses and loss adjustment expenses and reinsurance balances recoverable on paid and unpaid losses for certain retroactive reinsurance contracts where we have elected the fair value option in our Non-life Run-off segment. The fair value was calculated as the aggregate of discounted cash flows plus a risk margin. The discounted cash flow approach uses (i) estimated nominal cash flows based upon an appropriate payment pattern developed in accordance with standard actuarial techniques and (ii) a discount rate based upon a high quality rated corporate bond yield plus a credit spread for non-performance risk. The model uses corporate bond rates across the yield curve depending on the estimated timing of the future cash flows and specific to the currency of the risk. The risk margin was calculated using the present value of the cost of capital. The cost of capital approach uses (i) projected capital requirements, (ii) multiplied by the risk cost of capital representing the return required for non-hedgeable risk based upon the weighted average cost of capital less investment income and (iii) discounted using the weighted average cost of capital. Derivative Instruments The fair values of our derivative instruments, as described in Note 7 - "Derivatives and Hedging Instruments," are classified as Level 2. The fair values are based upon prices in active markets for identical contracts. Level 3 Measurements and Changes in Leveling Transfers into or out of levels are recorded at their fair values as of the end of the reporting period, consistent with the date of determination of fair value. Investments The following tables present a reconciliation of the beginning and ending balances for all investments measured at fair value on a recurring basis using Level 3 inputs during the years ended December 31, 2020 and 2019: 2020 Privately-held Equities Other Investments Total Beginning fair value $ 265,799 $ 87,869 $ 353,668 Purchases 20,125 47,092 67,217 Sales — (1,289) (1,289) Total realized and unrealized losses (11,183) (40,368) (51,551) Transfer out of Level 3 into Level 2 — (83,740) (83,740) Ending fair value $ 274,741 $ 9,564 $ 284,305 2019 Fixed maturity investments Privately-held Equities Other Investments Total Corporate Residential mortgage-backed Commercial mortgage-backed Asset-backed Beginning fair value $ 37,386 $ — $ 7,389 $ 9,121 $ 228,710 $ 39,367 $ 321,973 Purchases 184 — — — 30,713 56,908 87,805 Sales (3,520) — (784) (3,605) (2,016) (590) (10,515) Total realized and unrealized gains (losses) 90 (1) 64 255 8,392 (7,816) 984 Transfer into Level 3 from Level 2 3,535 102 1,515 21,024 — — 26,176 Transfer out of Level 3 into Level 2 (37,675) (101) (8,184) (26,795) — — (72,755) Ending fair value $ — $ — $ — $ — $ 265,799 $ 87,869 $ 353,668 Net realized and unrealized gains related to Level 3 assets in the table above are included in net realized and unrealized gains (losses) in our consolidated statements of earnings. The securities transferred from Level 2 to Level 3 were transferred due to insufficient market observable inputs for the valuation of the specific assets. The transfers from Level 3 to Level 2 were based upon obtaining market observable information regarding the valuations of the specific assets. Valuations Techniques and Inputs The table below presents the quantitative information related to the fair value measurements for our privately held equity investments measured at fair value on a recurring basis using Level 3 inputs: Quantitative Information about Level 3 Fair Value Measurements Fair Value as of December 31, 2020 Valuation Techniques Unobservable Input Average (1) (in millions of U.S. dollars) $ 230.3 Guideline company methodology Distribution waterfall 12.98 $ 54.0 Cost as approximation of fair value Cost as approximation of fair value $ 284.3 (1) The average represents the arithmetic average of the inputs and is not weighted by the relative fair value. Insurance Contracts - Fair Value Option The following table presents a reconciliation of the beginning and ending balances for all insurance contracts measured at fair value on a recurring basis using Level 3 inputs during the years ended December 31, 2020 and 2019: 2020 2019 Liability for losses and LAE Reinsurance balances recoverable on paid and unpaid losses Net Liability for losses and LAE Reinsurance balances recoverable on paid and unpaid losses Net Beginning fair value $ 2,621,122 $ 695,518 $ 1,925,604 $ 2,874,055 $ 739,591 $ 2,134,464 Assumed business 1,526 (180,972) 182,498 9,218 — 9,218 Incurred losses and LAE: Reduction in estimates of ultimate losses (73,596) 59,478 (133,074) (32,690) (2,958) (29,732) Reduction in unallocated LAE (17,484) — (17,484) (19,915) — (19,915) Change in fair value 157,965 38,919 119,046 160,630 43,449 117,181 Total incurred losses and LAE 66,885 98,397 (31,512) 108,025 40,491 67,534 Paid losses (300,234) (101,326) (198,908) (416,770) (92,145) (324,625) Effect of exchange rate movements 63,621 9,213 54,408 46,594 7,581 39,013 Ending fair value $ 2,452,920 $ 520,830 $ 1,932,090 $ 2,621,122 $ 695,518 $ 1,925,604 The net assumed business of $182.5 million in the current period relates to the Hannover Re novation transaction disclosed in Note 4 - "Significant New Business." Changes in fair value in the table above are included in net incurred losses and LAE in our consolidated statements of earnings. The following table presents the components of the net change in fair value for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Changes in fair value due to changes in: Duration $ 20,861 $ 22,719 $ 74,011 Corporate bond yield 96,478 94,462 (71,031) Weighted cost of capital (5,048) — Risk cost of capital 6,755 — 3,684 Change in fair value $ 119,046 $ 117,181 $ 6,664 Below is a summary of the quantitative information regarding the significant observable and unobservable inputs used in the internal model to determine fair value on a recurring basis as of December 31, 2020 and 2019: 2020 2019 Valuation Technique Unobservable (U) and Observable (O) Inputs Weighted Average Weighted Average Internal model Corporate bond yield (O) A rated A rated Internal model Credit spread for non-performance risk (U) 0.2% 0.2% Internal model Risk cost of capital (U) 5.1% 5.1% Internal model Weighted average cost of capital (U) 8.25% 8.5% Internal model Duration - liability (U) 8.17 years 7.82 years Internal model Duration - reinsurance balances recoverable on paid and unpaid losses (U) 8.23 years 8.68 years The fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses may increase or decrease due to changes in the corporate bond rate, the credit spread for non-performance risk, the risk cost of capital, the weighted average cost of capital and the estimated payment pattern as described below: • An increase in the corporate bond rate or credit spread for non-performance risk would result in a decrease in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses. Conversely, a decrease in the corporate bond rate or credit spread for non-performance risk would result in an increase in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses. • An increase in the weighted average cost of capital would result in an increase in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses. Conversely, a decrease in the weighted average cost of capital would result in a decrease in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses. • An increase in the risk cost of capital would result in an increase in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses. Conversely, a decrease in the risk cost of capital would result in a decrease in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses. • The duration of the liability and recoverable is adjusted every period to reflect actual net payments during the period and expected future payments. An acceleration of the estimated payment pattern, a decrease in duration, would result in an increase in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses. Conversely, a deceleration of the estimated payment pattern, an increase in duration, would result in a decrease in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses. In addition, the estimate of the capital required to support the liabilities is based upon current industry standards for capital adequacy. If the required capital per unit of risk increases, then the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses would increase. Conversely, a decrease in required capital would result in a decrease in the fair value of the liability for losses and LAE and reinsurance balances recoverable on paid and unpaid losses. Disclosure of Fair Values for Financial Instruments Carried at Cost Senior Notes As of December 31, 2020, our 4.50% Senior Notes due 2022 (the "2022 Senior Notes") and our 4.95% Senior Notes due 2029 (the "2029 Senior Notes" and, together with the 2022 Senior Notes, the "Senior Notes") were carried at amortized cost of $349.3 million and $494.2 million, respectively, while the fair value based on observable market pricing from a third party pricing service was $362.4 million and $573.3 million, respectively. The Senior Notes are classified as Level 2. Junior Subordinated Notes As of December 31, 2020, our 5.75% Fixed-Rate Reset Junior Subordinated Notes due 2040 (the “Junior Subordinated Notes”) were carried at amortized cost of $344.8 million, while the fair value based on observable market pricing from a third party pricing service was $365.7 million. The Junior Subordinated Notes are classified as Level 2. Insurance Contracts Disclosure of fair value of amounts relating to insurance contracts is not required, except those for which we elected the fair value option, as described above. Remaining Assets and Liabilities Our remaining assets and liabilities were generally carried at cost or amortized cost, which due to their short-term nature approximates fair value as of December 31, 2020 and 2019.

Premiums Written and Earned

Premiums Written and Earned	12 Months Ended
	Dec. 31, 2020
Insurance [Abstract]
PREMIUMS WRITTEN AND EARNED	$1 million 539,428 158,174 697,602 33.4 % Other reinsurers < $1 million 23,765 3,203 26,968 1.3 % Total $ 1,599,869 $ 489,294 $ 2,089,163 100.0 % December 31, 2019 Non-life Atrium StarStone Total % of Top 10 reinsurers $ 1,154,110 $ 22,051 $ 295,443 $ 1,471,604 67.4 % Other reinsurers > $1 million 551,636 7,761 129,335 688,732 31.6 % Other reinsurers < $1 million 19,243 545 1,010 20,798 1.0 % Total $ 1,724,989 $ 30,357 $ 425,788 $ 2,181,134 100.0 % December 31, 2020 December 31, 2019 Information regarding top ten reinsurers: Number of top 10 reinsurers rated A- or better 7 8 Number of top 10 non-rated reinsurers (1) 3 2 Reinsurers rated A- or better in top 10 $ 863,819 $ 1,199,479 Non-rated reinsurers in top 10 (1) 500,774 272,125 Total top 10 reinsurance recoverables $ 1,364,593 $ 1,471,604 Single reinsurers that represent 10% or more of total reinsurance balance recoverables as of December 31, 2020 and 2019: Hannover Ruck SE (2) $ — $ 259,077 Lloyd's Syndicates (3) $ 331,118 $ 396,246 Michigan Catastrophic Claims Association (4) $ 229,374 $ — (1) The reinsurance balances recoverable from the three and two non-rated top 10 reinsurers as of December 31, 2020 and 2019, respectively, was comprised of: • $229.4 million and $190.8 million as of December 31, 2020 and December 31, 2019 respectively, due from a U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state; • $73.8 million and $81.4 million as of December 31, 2020 and December 31, 2019 respectively, due from a reinsurer who has provided us with security in the form of pledged assets in trust for the full amount of the recoverable balance; and • $208.4 million as of December 31, 2020 due from Enhanzed Re, an equity method investee to whom some of our subsidiaries have retroceded their exposures through quota share reinsurance agreements as discussed in Note 21 - "Related Party Transactions". These quota share reinsurance agreements are written on a funds withheld basis with our subsidiaries retaining the retrocession premium consideration, to secure the full amount of the recoverable balances due from Enhanzed Re. (2) Hannover Ruck SE is rated AA- by Standard & Poor’s and A+ by A.M. Best. The transaction described in Note 4 - "Significant New Business" had the effect of reducing the balances due from this reinsurer to below 10% of the total reinsurance balances recoverable as of December 31, 2020. (3) Lloyd's Syndicates are rated A+ by Standard & Poor's and A by A.M. Best. (4) U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state. We evaluate and monitor the credit risk related to our reinsurers, and an allowance for estimated uncollectible reinsurance balances recoverable on paid and unpaid losses ("allowance for estimated uncollectible reinsurance") is established for amounts considered potentially uncollectible. With respect to our process for determining the allowances for estimated uncollectible reinsurance, we adopted ASU 2016-13 and the related amendments on January 1, 2020 and recorded a cumulative effect adjustment of $0.2 million to increase the opening retained earnings on the initial adoption of the guidance. Our allowance for estimated uncollectible reinsurance is derived based on various data sources, multiple key inputs and forecast scenarios. These include the duration of the collection period, credit quality, changes in reinsurer credit standing, default rates specific to the individual reinsurer, the geographical location of the reinsurer, contractual disputes with reinsurers over individual contentious claims, contract language or coverage issues, industry analyst reports and consensus economic forecasts. To determine the allowance for estimated uncollectible reinsurance, we use the PD and LGD methodology whereby each reinsurer is allocated an appropriate PD percentage based on the expected payout duration by portfolio. This PD percentage is then multiplied by an appropriate LGD percentage to arrive at an overall credit allowance percentage which is then applied to the reinsurance balance recoverable for each reinsurer, net of any specific bad debt provisions, collateral or other contract related offsets, to arrive at the overall allowance for estimated uncollectible reinsurance by reinsurer. The following tables show our gross and net balances recoverable from our reinsurers as well as the related allowance for estimated uncollectible reinsurance broken down by the credit ratings of our reinsurers. The majority of the allowance for estimated uncollectible reinsurance relates to the Non-life Run-off segment. December 31, 2020 Gross Allowance for estimated uncollectible reinsurance Net Provisions as a Reinsurers rated A- or above $ 1,464,529 $ 60,801 $ 1,403,728 4.2 % Reinsurers rated below A-, secured 608,999 — 608,999 — % Reinsurers rated below A-, unsecured 152,757 76,321 76,436 50.0 % Total $ 2,226,285 $ 137,122 $ 2,089,163 6.2 % December 31, 2019 Gross Allowance for estimated uncollectible reinsurance Net Provisions as a Reinsurers rated A- or above $ 1,731,270 $ 43,427 $ 1,687,843 2.5 % Reinsurers rated below A-, secured 463,840 — 463,840 — % Reinsurers rated below A-, unsecured 133,663 104,212 29,451 78.0 % Total $ 2,328,773 $ 147,639 $ 2,181,134 6.3 % The table below provides a reconciliation of the beginning and ending allowance for estimated uncollectible reinsurance balances for the years ended December 31, 2020 and 2019: 2020 2019 Allowance for estimated uncollectible reinsurance, beginning of year $ 147,639 $ 156,732 Cumulative effect of change in accounting principle (195) — Effect of exchange rate movement 700 (887) Current period change in the allowance (381) 2,077 Write-offs charged against the allowance (9,625) (9,871) Recoveries collected (1,016) (412) Allowance for estimated uncollectible reinsurance, end of year $ 137,122 $ 147,639 13. PREMIUMS WRITTEN AND EARNED The following tables provide a summary of net premiums written and earned for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Premiums Premiums Premiums Premiums Premiums Premiums Non-life Run-off Gross $ 5,191 $ 71,522 $ (25,069) $ 197,009 $ (8,910) $ 25,230 Ceded (2,204) (12,827) (269) (28,513) (307) (15,803) Net $ 2,987 $ 58,695 $ (25,338) $ 168,496 $ (9,217) $ 9,427 Atrium Gross $ 206,656 $ 197,492 $ 192,373 $ 182,678 $ 171,494 $ 164,428 Ceded (23,462) (22,099) (20,017) (18,619) (18,006) (18,113) Net $ 183,194 $ 175,393 $ 172,356 $ 164,059 $ 153,488 $ 146,315 StarStone Gross $ 326,695 $ 441,015 $ 472,815 $ 549,299 $ 622,570 $ 647,218 Ceded (93,493) (122,900) (93,292) (98,187) (144,561) (132,055) Net $ 233,202 $ 318,115 $ 379,523 $ 451,112 $ 478,009 $ 515,163 Other Gross $ 13,441 $ 19,889 $ 18,534 $ 20,544 $ 32,378 $ 25,237 Ceded — — (22) (164) (311) (363) Net $ 13,441 $ 19,889 $ 18,512 $ 20,380 $ 32,067 $ 24,874 Total Gross $ 551,983 $ 729,918 $ 658,653 $ 949,530 $ 817,532 $ 862,113 Ceded (119,159) (157,826) (113,600) (145,483) (163,185) (166,334) Net $ 432,824 $ 572,092 $ 545,053 $ 804,047 $ 654,347 $ 695,779 " id="sjs-B4" xml:space="preserve">8. REINSURANCE BALANCES RECOVERABLE ON PAID AND UNPAID LOSSES The following tables provide the total reinsurance balances recoverable on paid and unpaid losses. December 31, 2020 Non-life StarStone Total Recoverable from reinsurers on unpaid: Outstanding losses $ 938,231 $ 263,638 $ 1,201,869 IBNR 508,082 139,761 647,843 ULAE 16,688 — 16,688 Fair value adjustments - acquired companies (14,014) (1,339) (15,353) Fair value adjustments - fair value option (21,427) — (21,427) Total reinsurance reserves recoverable 1,427,560 402,060 1,829,620 Paid losses recoverable 172,309 87,234 259,543 Total $ 1,599,869 $ 489,294 $ 2,089,163 Reconciliation to Consolidated Balance Sheet: Reinsurance balances recoverable on paid and unpaid losses $ 1,079,039 $ 489,294 $ 1,568,333 Reinsurance balances recoverable on paid and unpaid losses - fair value option 520,830 — 520,830 Total $ 1,599,869 $ 489,294 $ 2,089,163 December 31, 2019 Non-life Atrium StarStone Total Recoverable from reinsurers on unpaid: Outstanding losses $ 972,293 $ 9,011 $ 264,131 $ 1,245,435 IBNR 673,059 19,286 93,185 785,530 Fair value adjustments - acquired companies (13,652) 519 (2,122) (15,255) Fair value adjustments - fair value option (88,086) — — (88,086) Total reinsurance reserves recoverable 1,543,614 28,816 355,194 1,927,624 Paid losses recoverable 181,375 1,541 70,594 253,510 Total $ 1,724,989 $ 30,357 $ 425,788 $ 2,181,134 Reconciliation to Consolidated Balance Sheet: Reinsurance balances recoverable on paid and unpaid losses $ 1,029,471 $ 30,357 $ 425,788 $ 1,485,616 Reinsurance balances recoverable on paid and unpaid losses - fair value option 695,518 — — 695,518 Total $ 1,724,989 $ 30,357 $ 425,788 $ 2,181,134 Our (re)insurance run-off subsidiaries and assumed portfolios, prior to acquisition, used retrocessional agreements to reduce their exposure to the risk of (re)insurance assumed. On an annual basis, both Atrium (classified as held-for-sale as of December 31, 2020) and StarStone purchased a tailored outwards reinsurance program designed to manage their risk profiles. The majority of Atrium’s and StarStone's third-party reinsurance is with highly rated reinsurers or is collateralized by pledged assets or letters of credit. The fair value adjustments, determined on acquisition of (re)insurance subsidiaries, are based on the estimated timing of loss and LAE recoveries and an assumed interest rate equivalent to a risk free rate for securities with similar duration to the acquired reinsurance balances recoverable on paid and unpaid losses plus a spread for credit risk, and are amortized over the estimated recovery period, as adjusted for accelerations in timing of payments as a result of commutation settlements. The determination of the fair value adjustments on the retroactive reinsurance contracts for which we have elected the fair value option is described in Note 12 - "Fair Value Measurements". As of December 31, 2020 and 2019, we had reinsurance balances recoverable on paid and unpaid losses of $2.1 billion and $2.2 billion, respectively. The decrease of $92.0 million was primarily due to the Hannover Re transaction, cash collections and the classification of Atrium as held-for-sale at December 31, 2020, partially offset by increases due to the retrocession to Enhanzed Re as discussed in Note 21 - "Related Party Transactions" Top Ten Reinsurers December 31, 2020 Non-life StarStone Total % of Top 10 reinsurers $ 1,036,676 $ 327,917 $ 1,364,593 65.3 % Other reinsurers > $1 million 539,428 158,174 697,602 33.4 % Other reinsurers < $1 million 23,765 3,203 26,968 1.3 % Total $ 1,599,869 $ 489,294 $ 2,089,163 100.0 % December 31, 2019 Non-life Atrium StarStone Total % of Top 10 reinsurers $ 1,154,110 $ 22,051 $ 295,443 $ 1,471,604 67.4 % Other reinsurers > $1 million 551,636 7,761 129,335 688,732 31.6 % Other reinsurers < $1 million 19,243 545 1,010 20,798 1.0 % Total $ 1,724,989 $ 30,357 $ 425,788 $ 2,181,134 100.0 % December 31, 2020 December 31, 2019 Information regarding top ten reinsurers: Number of top 10 reinsurers rated A- or better 7 8 Number of top 10 non-rated reinsurers (1) 3 2 Reinsurers rated A- or better in top 10 $ 863,819 $ 1,199,479 Non-rated reinsurers in top 10 (1) 500,774 272,125 Total top 10 reinsurance recoverables $ 1,364,593 $ 1,471,604 Single reinsurers that represent 10% or more of total reinsurance balance recoverables as of December 31, 2020 and 2019: Hannover Ruck SE (2) $ — $ 259,077 Lloyd's Syndicates (3) $ 331,118 $ 396,246 Michigan Catastrophic Claims Association (4) $ 229,374 $ — (1) The reinsurance balances recoverable from the three and two non-rated top 10 reinsurers as of December 31, 2020 and 2019, respectively, was comprised of: • $229.4 million and $190.8 million as of December 31, 2020 and December 31, 2019 respectively, due from a U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state; • $73.8 million and $81.4 million as of December 31, 2020 and December 31, 2019 respectively, due from a reinsurer who has provided us with security in the form of pledged assets in trust for the full amount of the recoverable balance; and • $208.4 million as of December 31, 2020 due from Enhanzed Re, an equity method investee to whom some of our subsidiaries have retroceded their exposures through quota share reinsurance agreements as discussed in Note 21 - "Related Party Transactions". These quota share reinsurance agreements are written on a funds withheld basis with our subsidiaries retaining the retrocession premium consideration, to secure the full amount of the recoverable balances due from Enhanzed Re. (2) Hannover Ruck SE is rated AA- by Standard & Poor’s and A+ by A.M. Best. The transaction described in Note 4 - "Significant New Business" had the effect of reducing the balances due from this reinsurer to below 10% of the total reinsurance balances recoverable as of December 31, 2020. (3) Lloyd's Syndicates are rated A+ by Standard & Poor's and A by A.M. Best. (4) U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state. We evaluate and monitor the credit risk related to our reinsurers, and an allowance for estimated uncollectible reinsurance balances recoverable on paid and unpaid losses ("allowance for estimated uncollectible reinsurance") is established for amounts considered potentially uncollectible. With respect to our process for determining the allowances for estimated uncollectible reinsurance, we adopted ASU 2016-13 and the related amendments on January 1, 2020 and recorded a cumulative effect adjustment of $0.2 million to increase the opening retained earnings on the initial adoption of the guidance. Our allowance for estimated uncollectible reinsurance is derived based on various data sources, multiple key inputs and forecast scenarios. These include the duration of the collection period, credit quality, changes in reinsurer credit standing, default rates specific to the individual reinsurer, the geographical location of the reinsurer, contractual disputes with reinsurers over individual contentious claims, contract language or coverage issues, industry analyst reports and consensus economic forecasts. To determine the allowance for estimated uncollectible reinsurance, we use the PD and LGD methodology whereby each reinsurer is allocated an appropriate PD percentage based on the expected payout duration by portfolio. This PD percentage is then multiplied by an appropriate LGD percentage to arrive at an overall credit allowance percentage which is then applied to the reinsurance balance recoverable for each reinsurer, net of any specific bad debt provisions, collateral or other contract related offsets, to arrive at the overall allowance for estimated uncollectible reinsurance by reinsurer. The following tables show our gross and net balances recoverable from our reinsurers as well as the related allowance for estimated uncollectible reinsurance broken down by the credit ratings of our reinsurers. The majority of the allowance for estimated uncollectible reinsurance relates to the Non-life Run-off segment. December 31, 2020 Gross Allowance for estimated uncollectible reinsurance Net Provisions as a Reinsurers rated A- or above $ 1,464,529 $ 60,801 $ 1,403,728 4.2 % Reinsurers rated below A-, secured 608,999 — 608,999 — % Reinsurers rated below A-, unsecured 152,757 76,321 76,436 50.0 % Total $ 2,226,285 $ 137,122 $ 2,089,163 6.2 % December 31, 2019 Gross Allowance for estimated uncollectible reinsurance Net Provisions as a Reinsurers rated A- or above $ 1,731,270 $ 43,427 $ 1,687,843 2.5 % Reinsurers rated below A-, secured 463,840 — 463,840 — % Reinsurers rated below A-, unsecured 133,663 104,212 29,451 78.0 % Total $ 2,328,773 $ 147,639 $ 2,181,134 6.3 % The table below provides a reconciliation of the beginning and ending allowance for estimated uncollectible reinsurance balances for the years ended December 31, 2020 and 2019: 2020 2019 Allowance for estimated uncollectible reinsurance, beginning of year $ 147,639 $ 156,732 Cumulative effect of change in accounting principle (195) — Effect of exchange rate movement 700 (887) Current period change in the allowance (381) 2,077 Write-offs charged against the allowance (9,625) (9,871) Recoveries collected (1,016) (412) Allowance for estimated uncollectible reinsurance, end of year $ 137,122 $ 147,639 13. PREMIUMS WRITTEN AND EARNED The following tables provide a summary of net premiums written and earned for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Premiums Premiums Premiums Premiums Premiums Premiums Non-life Run-off Gross $ 5,191 $ 71,522 $ (25,069) $ 197,009 $ (8,910) $ 25,230 Ceded (2,204) (12,827) (269) (28,513) (307) (15,803) Net $ 2,987 $ 58,695 $ (25,338) $ 168,496 $ (9,217) $ 9,427 Atrium Gross $ 206,656 $ 197,492 $ 192,373 $ 182,678 $ 171,494 $ 164,428 Ceded (23,462) (22,099) (20,017) (18,619) (18,006) (18,113) Net $ 183,194 $ 175,393 $ 172,356 $ 164,059 $ 153,488 $ 146,315 StarStone Gross $ 326,695 $ 441,015 $ 472,815 $ 549,299 $ 622,570 $ 647,218 Ceded (93,493) (122,900) (93,292) (98,187) (144,561) (132,055) Net $ 233,202 $ 318,115 $ 379,523 $ 451,112 $ 478,009 $ 515,163 Other Gross $ 13,441 $ 19,889 $ 18,534 $ 20,544 $ 32,378 $ 25,237 Ceded — — (22) (164) (311) (363) Net $ 13,441 $ 19,889 $ 18,512 $ 20,380 $ 32,067 $ 24,874 Total Gross $ 551,983 $ 729,918 $ 658,653 $ 949,530 $ 817,532 $ 862,113 Ceded (119,159) (157,826) (113,600) (145,483) (163,185) (166,334) Net $ 432,824 $ 572,092 $ 545,053 $ 804,047 $ 654,347 $ 695,779

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	14. GOODWILL AND INTANGIBLE ASSETS The following table presents a reconciliation of the beginning and ending goodwill and intangible assets, included within other assets in the consolidated balance sheets, for the years ended December 31, 2020 and 2019: Goodwill Intangible Intangible assets with an indefinite life Total Balance as of December 31, 2018 $ 109,807 $ 16,887 $ 67,131 $ 193,825 Amortization — (2,257) — (2,257) Balance as of December 31, 2019 $ 109,807 $ 14,630 $ 67,131 $ 191,568 Amortization — (1,524) — (1,524) Impairment losses (StarStone International) (1) (8,000) — (4,000) (12,000) Reclassification to assets held-for-sale (Atrium) (2) (38,848) (13,106) (63,131) (115,085) Balance as of December 31, 2020 $ 62,959 $ — $ — $ 62,959 (1) On June 10, 2020, we announced the StarStone International Run-Off. During the year ended December 31, 2020, we recognized impairment losses of $8.0 million related to the goodwill allocated to StarStone International and $4.0 million on StarStone's Lloyd's syndicate capacity. (2) On August 13, 2020, we announced the Atrium Exchange Transaction, which resulted in the assets and liabilities of the Atrium segment being classified as held-for-sale as of December 31, 2020. Refer to Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations" for further information. The gross carrying value, accumulated amortization and net carrying value of goodwill and intangible assets by segment and by type as of December 31, 2020 and 2019 was as follows: December 31, 2020 December 31, 2019 Gross Accumulated amortization Net Gross Accumulated amortization Net Non-life Run-off segment: Goodwill $ 62,959 $ — $ 62,959 $ 62,959 $ — $ 62,959 Atrium segment: Goodwill — — — 38,848 — 38,848 Intangible assets with a definite life: Distribution channel — — — 20,000 (8,111) 11,889 Brand — — — 7,000 (4,259) 2,741 Intangible assets with an indefinite life: Lloyd’s syndicate capacity — — — 33,031 — 33,031 Management contract — — — 30,100 — 30,100 Total Atrium segment goodwill and intangible assets — — — 128,979 (12,370) 116,609 StarStone segment: Goodwill — — — 8,000 — 8,000 Intangible assets with an indefinite life: Lloyd’s syndicate capacity — — — 4,000 — 4,000 Total StarStone segment goodwill and intangible assets — — — 12,000 — 12,000 Total goodwill and intangible assets $ 62,959 $ — $ 62,959 $ 203,938 $ (12,370) $ 191,568 The amortization recorded on the intangible assets of the Atrium segment, prior to the reclassification to held-for-sale, for the years ended December 31, 2020, 2019 and 2018 was $1.5 million, $2.3 million and $3.6 million, respectively.

Debt Obligations and Credit Fac

Debt Obligations and Credit Facilities	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Debt Obligations and Credit Facilities	15. DEBT OBLIGATIONS AND CREDIT FACILITIES We utilize debt and credit facilities primarily for funding acquisitions and significant new business, investment activities and, from time to time, for general corporate purposes. Our debt obligations were as follows: Facility Origination Date Term December 31, 2020 December 31, 2019 4.50% Senior Notes due 2022 March 10, 2017 5 years $ 349,253 $ 348,616 4.95% Senior Notes due 2029 May 28, 2019 10 years 494,194 493,600 Total Senior Notes 843,447 842,216 5.75% Junior Subordinated Notes due 2040 August 26, 2020 20 years 344,812 — EGL Revolving Credit Facility August 16, 2018 5 years 185,000 — 2018 EGL Term Loan Facility December 27, 2018 3 years — 348,991 Total debt obligations $ 1,373,259 $ 1,191,207 In 2020, we issued the Junior Subordinated Notes and fully repaid the 2018 EGL Term Loan Facility. The table below provides a summary of the total interest expense for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Interest expense on debt obligations $ 57,974 $ 51,245 $ 25,205 Amortization of debt issuance costs 1,331 953 537 Funds withheld balances and other 3 343 (46) Total interest expense $ 59,308 $ 52,541 $ 25,696 Senior Notes We have issued two series of Senior Notes as shown in the table above. The Senior Notes are effectively subordinated to any of our secured indebtedness to the extent of the value of the assets securing such indebtedness, and structurally subordinated to all liabilities of our subsidiaries, including claims of policyholders. The 2022 Senior Notes and the 2029 Senior Notes bear interest at a fixed rate per annum, equal to 4.50% and 4.95%, respectively. Both series of Senior Notes are rated BBB-. We may repurchase the 2029 Senior Notes at any time prior to three months prior to maturity of the 2029 Senior Notes, subject to the payment of a make-whole premium. After such date, we may repurchase the 2029 Senior Notes at a purchase price equal to 100% of the outstanding principal amount, plus accrued and unpaid interest. We do not have the right to repurchase the 2022 Senior Notes prior to their maturity. We incurred costs of $2.9 million and $6.8 million in issuing the 2022 and 2029 Senior Notes, respectively. The unamortized costs as of December 31, 2020 were $0.7 million and $5.8 million, respectively. Junior Subordinated Notes 5.75% Junior Subordinated Notes due 2040 On August 26, 2020, our wholly-owned subsidiary, Enstar Finance LLC ("Enstar Finance") issued the Junior Subordinated Notes in an aggregate principal amount of $350.0 million. The Junior Subordinated Notes bear interest (i) during the initial five-year period ending August 30, 2025, at a fixed rate per annual of 5.75% and (ii) during each five-year reset period thereafter beginning September 1, 2025, at a fixed rate per annum equal to the five-year U.S. treasury rate calculated as of two business days prior to the beginning of such five-year period plus 5.468%. The Junior Subordinated Notes are rated BB+ and are unsecured junior subordinated obligations of Enstar Finance. The Junior Subordinated Notes are fully and unconditionally guaranteed by us on an unsecured and junior subordinated basis. These debt securities of Enstar Finance are effectively subordinated to the obligations of our other subsidiaries. Subject to certain requirements and during certain time periods, Enstar Finance may repurchase the Junior Subordinated Notes, in whole or in part, at any time, at a repurchase price equal to at least 100% of the principal amount, plus accrued and unpaid interest. EGL Revolving Credit Facility On August 16, 2018, we entered into a five-year, As of December 31, 2020, we were permitted to borrow up to an aggregate of $600.0 million under the revolving credit facility. As of December 31, 2020, there was $415.0 million of available unutilized capacity under the facility. Subsequent to December 31, 2020, we borrowed an additional $20.0 million and repaid $30.0 million, increasing the unutilized capacity under the facility to $425.0 million. We pay interest on loans borrowed under the facility at a per annum rate comprising a reference rate determined based on the type of loan we borrow plus a margin based on the Company's long term senior unsecured debt ratings. The applicable reference rate is adjusted base rate for base rate loans and adjusted LIBOR 2018 EGL Term Loan Facility On December 27, 2018, we entered into and fully utilized a three-year, Maturities As of December 31, 2020, the amount of outstanding debt obligations that will become due in each of the next five years and thereafter was as follows: 2021, $0; 2022, $350.0 million; 2023, $185.0 million; 2024, $0; and thereafter, $850.0 million. Letters of Credit We utilize unsecured and secured letters of credit to support certain of our (re)insurance performance obligations. $275.0 million Funds at Lloyd's Letter of Credit Facility On November 5, 2020, we amended and restated our Fund's at Lloyd's letter of credit facility to reduce its capacity to $275.0 million (with the right to request additional commitments under the facility in an aggregate amount not to exceed $75.0 million) and extended its term by two years. We use letters of credit under this facility to satisfy a portion of our Funds at Lloyd's requirements, and letters of credit issued under the facility will expire at the end of 2025. As of December 31, 2020 and December 31, 2019, our combined Funds at Lloyd's comprised cash and investments of $260.9 million and $639.3 million, respectively, and unsecured letters of credit of $210.0 million and $252.0 million, respectively. $120.0 million Letter of Credit Facility We use this facility to provide collateral support for certain reinsurance obligations of our subsidiaries. We may request additional commitments under the facility in an aggregate amount not to exceed $60.0 million, which the existing lender in its discretion or new lenders may provide, in each case subject to the terms of the agreement. As of December 31, 2020 and December 31, 2019, The aggregate amount of letters of credit issued under the facility was $115.7 million and $115.3 million, respectively. $800.0 million Syndicated Letter of Credit Facility On August 4, 2020, we increased the total commitments available under this facility by an aggregate amount of $40.0 million, bringing the total size of the facility to $800.0 million. We use this facility to collateralize certain reinsurance obligations. As of December 31, 2020 and December 31, 2019, the aggregate amount of letters of credit issued under the facility was $424.1 million and $608.0 million, respectively. $65.0 million Letter of Credit Facility On August 4, 2020, we entered into a $65.0 million letter of credit facility agreement pursuant to which we issued a letter of credit to collateralize a portion of our reinsurance obligations relating to our novation transaction Subsidiary Capital Letters of Credit We also utilize unsecured and secured letters of credit to support the regulatory capital requirements of certain of our subsidiaries. $100.0 million Bermuda Letter of Credit Facility On December 22, 2017, we entered into a $100.0 million subsidiary capital letter of credit facility agreement. The letter of credit issued under the agreement qualifies as eligible capital for one of our Bermuda regulated subsidiaries. As of December 31, 2020, the aggregate face amount of letters of credit under the facility was $100.0 million. GBP £32.0 million United Kingdom Letter of Credit Facility On December 8, 2020, we entered into a £32.0 million ($43.7 million) subsidiary capital letter of credit facility agreement. The letter of credit issued under the agreement qualifies as Ancillary Own Funds capital for one of our U.K. regulated subsidiaries. As of December 31, 2020, the aggregate face amount of letters of credit under the facility was $43.7 million.

Noncontrolling Interest

Noncontrolling Interest	12 Months Ended
	Dec. 31, 2020
Noncontrolling Interest [Abstract]
Noncontrolling Interest	16. NONCONTROLLING INTEREST We have both redeemable noncontrolling interest ("RNCI") and noncontrolling interest ("NCI") on our consolidated balance sheets. RNCI with redemption features that are not solely within our control are classified within temporary equity in the consolidated balance sheets and carried at redemption value, which is fair value. The change in fair value is recognized through retained earnings as if the balance sheet date were also the redemption date. In addition, we also have NCI, which does not have redemption features and is classified within equity in the consolidated balance sheets. Redeemable Noncontrolling Interest RNCI as of December 31, 2020 and 2019 comprised the ownership interests held by the Trident V Funds (39.3%) and the Dowling Funds (1.7%) in our subsidiary North Bay. As discussed in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations," North Bay owned our investments in Northshore, the holding company that owns Atrium and Arden, and SSHL, the holding company for the StarStone group. The following is a reconciliation of the beginning and ending carrying amount of the equity attributable to the RNCI for the years ended December 31, 2020 and 2019: 2020 2019 Balance at beginning of year $ 438,791 $ 458,543 Capital contributions — 13,127 Dividends paid — (11,556) Net losses attributable to RNCI (27,512) (12,029) Change in unrealized gains (losses) on AFS investments attributable to RNCI 1,517 (126) Change in currency translation adjustments attributable to RNCI (1,397) 10 Change in redemption value of RNCI (46,224) (9,178) Cumulative effect of change in accounting principle attributable to RNCI (1) 261 — Balance at end of year $ 365,436 $ 438,791 (1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details. We carried the RNCI at its estimated redemption value, which is fair value, as of December 31, 2020 and 2019. The decrease in the year ended December 31, 2020 included $27.5 million of net losses attributable to RNCI primarily arising on StarStone and which result from COVID-19 related net underwriting losses and exit costs associated with the decision to place StarStone International into run-off, partially offset by the gain on sale of StarStone U.S.; and $46.2 million due to change in redemption value. The redemption value decreased as a result of the StarStone International Run-Off decision and the agreement to sell both StarStone U.S and Northshore.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Shareholders' Equity	17. SHAREHOLDERS' EQUITY As of December 31, 2020 and 2019, the authorized share capital was 111,000,000 ordinary shares ("Voting Ordinary Shares") and non-voting convertible ordinary shares ("Non-Voting Ordinary Shares"), each of par value $1.00 per share, and 45,000,000 preferred shares of par value $1.00 per share. Voting Ordinary Shares Our Voting Ordinary Shares are listed and trade under the "ESGR" ticker symbol on the NASDAQ Global Select Market. Each Voting Ordinary Share entitles the holder thereof to one vote. Share Repurchases On March 9, 2020, our Board of Directors adopted a stock trading plan for the purpose of repurchasing a limited number of our Company’s ordinary shares, not to exceed $150.0 million in aggregate (the "Repurchase Program"). On March 23, 2020, we suspended our Repurchase Program due to uncertainty from the COVID-19 pandemic. The Repurchase Program resumed on September 21, 2020 and expires on March 1, 2021. From inception to December 31, 2020, we repurchased 178,280 ordinary shares at an average price of 145.87, for an aggregate price of $26.0 million under the Repurchase Program. As of December 31, 2020, the remaining capacity under the Repurchase Program was $124.0 million. We did not repurchase any shares subsequent to December 31, 2020. Joint Share Ownership Plan On January 21, 2020, 565,630 Voting Ordinary Shares were issued to the trustee of the Enstar Group Limited Employee Benefit Trust (the "EB Trust"). Voting rights in respect of shares held in the EB Trust have been contractually waived. We have consolidated the EB Trust, and shares held in the EB Trust are classified like treasury shares as contra-equity in our consolidated balance sheet. The EB Trust supports awards made under our Joint Share Ownership Plan, as described in Note 19 - "Share-Based Compensation and Pensions." Shares issued in acquisition of KaylaRe On May 14, 2018, 1,501,778 Voting Ordinary Shares were issued as consideration for the acquisition of KaylaRe Holdings Ltd, as described in Note 3 - "Business Acquisitions". Warrants As of December 31, 2020, there were warrants outstanding to acquire 175,901 Series C Non-Voting Ordinary Shares for an exercise price of $115.00 per share, subject to certain adjustments (the "Warrants"). The Warrants were issued in April 2011 and expire in April 2021. Series C Preferred Shares As of December 31, 2020, there were 388,571 Series C Participating Non-Voting Perpetual Preferred Shares ("Series C Preferred Shares") issued and held by one of our wholly-owned subsidiaries. The Series C Preferred Shares (i) upon liquidation, dissolution or winding up of the Company, entitle their holders to a preference over holders of our ordinary voting and non-voting shares of an amount equal to $0.001 per share with respect to surplus assets and (ii) are non-voting except in certain limited circumstances. The Series C Preferred shares have dividend rights equal to those of the ordinary voting shares, subject to certain limitations and in an amount determined by a "participation rate" that is generally reflective of the reduction in the number of Series C Preferred Shares issued in exchange for the previously outstanding Series A Shares. The Series C Preferred Shares otherwise rank on parity with the ordinary voting and non-voting shares, and they rank senior to each other class or series of share capital, unless the terms of any such class or series shall expressly provide otherwise. Dividends on Preferred Shares Holders of Series D and Series E Preferred Shares are entitled to receive, only when, as and if declared, non-cumulative cash dividends, paid quarterly in arrears on the 1st day of March, June, September and December of each year, commencing on September 1, 2018 for the Series D Preferred Shares and March 1, 2019 for the Series E Preferred Shares, of 7.00% per annum. Commencing on September 1, 2028, the Series D Preferred Shares will convert to a floating rate basis and dividends will be payable on a non-cumulative basis, when, as and if declared, at three-month LIBOR plus 4.015% per annum. Dividends that are not declared will not accumulate and will not be payable. During the years ended December 31, 2020, 2019 and 2018, we declared and paid dividends on Series D Preferred Shares of $28.0 million, $28.0 million and $12.1 million, respectively. During the years ended December 31, 2020 and 2019, we declared and paid dividends on Series E Preferred Shares of $7.7 million and $7.9 million, respectively. On February 5, 2021, we declared $7.0 million and $1.9 million of dividends on the Series D and E Preferred Shares, respectively, to be paid on March 1, 2021 to shareholders of record as of February 15, 2021. Any payment of dividends must be approved by our Board of Directors. Our ability to pay dividends is subject to certain restrictions, as described in Note 22 - "Dividend Restrictions and Statutory Financial Information". The following table presents a roll forward of accumulated other comprehensive income (loss): Unrealized gains (losses) arising during the year Cumulative Currency Translation Adjustment Defined Benefit Pension Liability Total Balance, December 31, 2017, net of tax $ 2,440 $ 11,171 $ (3,143) $ 10,468 Unrealized gains (losses) on fixed income available-for-sale investments arising during the year (2,284) — — (2,284) Reclassification adjustment for net realized (gains) losses included in net earnings 63 — — 63 Change in currency translation adjustment — (202) — (202) Decrease in defined benefit pension liability — — 2,156 2,156 Total other comprehensive income (loss) (2,221) (202) 2,156 (267) Other comprehensive (income) loss attributable to RNCI 222 17 — 239 Balance, December 31, 2018, net of tax 441 10,986 (987) 10,440 Unrealized gains (losses) on fixed income available-for-sale investments arising during the year 2,896 — — 2,896 Reclassification adjustment for net realized (gains) losses included in net earnings (3,894) — — (3,894) Change in currency translation adjustment — (2,428) — (2,428) Decrease in defined benefit pension liability — — 42 42 Total other comprehensive income (loss) (998) (2,428) 42 (3,384) Other comprehensive (income) loss attributable to RNCI 125 (10) — 115 Balance, December 31, 2019, net of tax (432) 8,548 (945) 7,171 Unrealized gains (losses) on fixed income available-for-sale investments arising during the year 104,924 — — 104,924 Reclassification adjustment for change in allowance for credit losses recognized in net earnings (509) — — (509) Reclassification adjustment for net realized (gains) losses included in net earnings (18,033) — — (18,033) Reclassification to earnings on disposal of subsidiary (11,856) 34 — (11,822) Change in currency translation adjustment — (2,103) — (2,103) Decrease in defined benefit pension liability — — 1,152 1,152 Total other comprehensive income (loss) 74,526 (2,069) 1,152 73,609 Other comprehensive (income) loss attributable to RNCI (1,518) 1,397 — (121) Balance, December 31, 2020, net of tax $ 72,576 $ 7,876 $ 207 $ 80,659 The following table presents details about the tax effects allocated to each component of other comprehensive income (loss): Before Tax Amount Tax (Expense) Benefit Net of Tax Amount Twelve months ended December 31, 2020 Unrealized gains (losses) on fixed income available-for-sale investments arising during the year $ 115,610 $ (10,686) $ 104,924 Reclassification adjustment for change in allowance for credit losses recognized in net earnings (499) (10) (509) Reclassification adjustment for net realized (gains) losses included in net earnings (19,766) 1,733 (18,033) Reclassification to earnings on disposal of subsidiary (15,008) 3,152 (11,856) Change in currency translation adjustment (2,294) 191 (2,103) Reclassification to earnings on disposal of subsidiary 34 — 34 Decrease in defined benefit pension liability 1,097 55 1,152 Other comprehensive income (loss) $ 79,174 $ (5,565) $ 73,609 In the year ended December 31, 2019 and 2018, the deferred tax (expense) benefit associated with items reported in other comprehensive income (loss) was subject to a full valuation allowance. For information on valuation allowances on deferred tax assets, refer to “Assessment of Valuation Allowance on Deferred Tax Assets” within Note 20 - "Income Taxation." The following table presents details amounts reclassified from accumulated other comprehensive income: Details about AOCI components 2020 2019 2018 Affected Line Item in Statement where Net Earnings are presented Unrealized gains (losses) on fixed income available-for-sale investments 18,682 3,894 (63) Net realized and unrealized gains (losses) 16,591 — — Net earnings from discontinued operations 35,273 3,894 (63) Total before tax (4,875) — — Income tax (expense) 30,398 3,894 (63) Net of tax Currency translation adjustment on disposal of subsidiary (34) — — Net earnings from discontinued operations Total reclassifications for the period, net of tax 30,364 3,894 (63)

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Earnings Per Share	18. EARNINGS PER SHARE The following table sets forth the computation of basic and diluted net earnings per ordinary share for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Numerator: Earnings (loss) per share attributable to Enstar ordinary shareholders: Net earnings (loss) from continuing operations (1) $ 1,711,810 $ 897,825 $ (163,232) Net earnings from discontinued operations (2) 7,534 4,350 878 Net earnings (loss) attributable to Enstar ordinary shareholders $ 1,719,344 $ 902,175 $ (162,354) Denominator: Weighted-average ordinary shares outstanding — basic (3) 21,551,408 21,482,617 20,698,310 Effect of dilutive securities: Share-based compensation plans (4) 208,293 227,878 129,746 Warrants 58,593 64,571 76,120 Weighted-average ordinary shares outstanding — diluted 21,818,294 21,775,066 20,904,176 Earnings (loss) per share attributable to Enstar ordinary shareholders: Basic: Net earnings (loss) from continuing operations $ 79.43 $ 41.80 $ (7.89) Net earnings from discontinued operations 0.35 0.20 0.05 Net earnings (loss) per ordinary share $ 79.78 $ 42.00 $ (7.84) Diluted (5) : Net earnings (loss) from continuing operations $ 78.45 $ 41.23 $ (7.89) Net earnings from discontinued operations 0.35 0.20 0.05 Net earnings (loss) per ordinary share $ 78.80 $ 41.43 $ (7.84) (1) Net earnings (loss) from continuing operations attributable to Enstar ordinary shareholders equals net earnings (loss) from continuing operations, plus net loss (earnings) from continuing operations attributable to noncontrolling interest, less dividends on preferred shares. (2) Net earnings (loss) from discontinued operations attributable to Enstar ordinary shareholders equals net earnings (loss) from discontinued operations, net of income taxes, plus net loss (earnings) from discontinued operations attributable to noncontrolling interest; refer to Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations" for a breakdown by period. (3) Weighted-average ordinary shares for basic earnings per share includes ordinary shares (voting and non-voting) but excludes ordinary shares held in the EB Trust in respect of JSOP awards. (4) Share-based dilutive securities include restricted shares, restricted share units, and performance share units. Certain share-based compensation awards, including the ordinary shares held in the EB Trust in respect of JSOP awards, were excluded from the calculation for the year ended December 31, 2020 because they were anti-dilutive. (5) During a period of loss, the basic weighted average ordinary shares outstanding is used in the denominator of the diluted loss per ordinary share computation as the effect of including potentially dilutive securities would be anti-dilutive.

Share-Based Compensation and Pe

Share-Based Compensation and Pensions	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Share-Based Compensation and Pensions	19. SHARE-BASED COMPENSATION AND PENSIONS Share-based compensation The 2016 and 2006 Equity Incentive Plans are our primary share-based compensation plans. We also maintain other share-based compensation plans as discussed below. The table below provides a summary of the compensation costs for all of our share-based compensation plans for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Share-based compensation plans: Restricted shares and restricted share units $ 8,286 $ 6,564 $ 7,641 Performance share units 12,678 23,582 1,968 Cash-settled stock appreciation rights 215 2,575 (3,316) Joint share ownership plan expense 4,296 — — Other share-based compensation plans: Northshore/Atrium incentive plan 971 3,652 2,792 StarStone incentive plan (223) 223 — Deferred compensation and ordinary share plan for non-employee directors 1,183 992 1,155 Employee share purchase plan 339 411 430 Total share-based compensation $ 27,745 $ 37,999 $ 10,670 The associated tax benefit recorded to income tax expense in the Consolidated statement of operations was $2.7 million, $2.9 million and $1.9 million for the years ended December 31, 2020, 2019 and 2018, respectively. Restricted Shares and Restricted Share Units Restricted shares and restricted share units are service awards that typically vest over three years. These awards are share-settled and are recorded in additional paid-in capital on the consolidated balance sheets. The fair value of these awards is measured at the grant date and expensed over the service period. The following table summarizes the activity related to restricted shares and restricted share awards during 2020: Number of Shares Weighted-Average Share Price Nonvested — January 1 64,572 $180.49 Granted 70,012 152.28 Vested (38,961) 174.93 Forfeited (373) 177.73 Nonvested — December 31 95,250 161.60 Performance Share Units ("PSUs") PSUs are share-settled and vest following the end of the three-year performance period. The number of shares to vest will be determined by a performance adjustment based on either (i) the change in fully diluted book value per share ("FDBVPS") over three years, or (ii) average annual non-GAAP operating income return on equity, excluding StarStone. Performance Share Units based on FDBVPS The following table summarizes the awards granted, the vested and unvested PSU awards at December 31, 2020, and the performance criteria and associated performance multipliers at various levels of achievement. Grant Year Inception-to-date Activity Roll-forward Performance Criteria: Performance Multiplier PSUs Granted Forfeited Estimated Change in Multiplier Vested Unvested at December 31, 2020 Threshold Target Target + Maximum Threshold Target Target + Maximum 2017 36,321 (12,267) 9,527 (33,581) — 20.00 % 30.00 % N/A 40.00 % 50.00 % 100.00 % N/A 150.00 % 2017 91,875 — 18,100 (109,975) — 30.30 % 35.65 % N/A 41.00 % 50.00 % 100.00 % N/A 150.00 % 2018 39,682 (12,545) 10,218 (6,700) 30,655 25.00 % 32.50 % N/A 40.00 % 50.00 % 100.00 % N/A 150.00 % 2019 18,308 (1,758) 7,835 (881) 23,504 20.00 % 30.00 % N/A 40.00 % 60.00 % 100.00 % N/A 150.00 % 2020 22,591 (2,151) — (701) 19,739 25.00 % 32.50 % N/A 40.00 % 60.00 % 100.00 % N/A 150.00 % 2020 52,948 — — — 52,948 33.10 % 36.80 % 44.30 % 52.10 % 50.00 % 100.00 % 150.00 % 200.00 % 261,725 (28,721) 45,680 (151,838) 126,846 For each type of PSU based on FDBVPS, a change in the FDBVPS Performance Criteria at each of Threshold, Target and Maximum will result in the application of the respective Threshold, Target and Maximum Performance Multiplier and a settlement of awards at that level. In addition, for the 2020 FDBVPS Type II award, a change in the FDBVPS Performance Criteria at "Target +" will result in the application of the "Target +" Performance Multiplier. Straight-line interpolation applies within these ranges, and no settlement occurs if the increase in FDBVPS is less than the Threshold. Performance Share Units based on Average Annual Non-GAAP Operating Income Return on Equity ("Operating ROE") The following table summarizes the awards granted, the vested and unvested units at December 31, 2020, and the performance criteria and associated performance multipliers at various levels of achievement. Grant Year Inception-to-date Activity Roll-forward Performance Criteria: Performance Multiplier PSUs Granted Forfeited Estimated Change in Multiplier Vested Unvested at December 31, 2020 Threshold Target Maximum Threshold Target Maximum 2019 18,308 (1,756) 7,811 (930) 23,433 9.60 % 12.00 % 14.40 % 60.00 % 100.00 % 150.00 % 2020 22,560 (2,151) — (701) 19,708 9.60 % 12.00 % 14.40 % 60.00 % 100.00 % 150.00 % 40,868 (3,907) 7,811 (1,631) 43,141 Annual Operating ROE is calculated based upon the non-GAAP operating income return on opening shareholder's equity, excluding StarStone. Average Annual Operating ROE is the sum of the three individual year annual operating ROE %'s divided by three. An Average Annual Operating ROE of Target to Maximum or more results in a settlement of 100% to a maximum of 150% of the units granted, respectively. An Average Annual Operating ROE of Threshold to Target results in a settlement of 60% to 100%. Straight-line interpolation applies within these ranges and no settlement occurs if the Average Annual Operating ROE is less than the Threshold. Performance Multipliers For expense purposes we assume a Target vesting at the initial time of award. At the end of each reporting period, we estimate the expected performance multiplier, as shown in the table below: Award Description 2020 2019 2018 2017 FDBVPS Type I (30.00% Target Change) 139% (1) 139% 50% 2017 FDBVPS Type II (35.65% Target Change) 120% (1) 120% 50% 2018 FDBVPS 150% (1) 100% 50% 2019 FDBVPS 150% 100% N/A 2019 Average Operating ROE 150% 100% N/A 2020 FDBVPS Type I (32.50% Target Change) 100% N/A N/A 2020 Average Operating ROE 100% N/A N/A 2020 FDBVPS Type II (36.80% Target Change) 100% N/A N/A (1) Multipliers for the 2017 and 2018 awards are the final achieved terms. The unrecognized compensation cost related to our unvested PSU share awards as of December 31, 2020 was $14.4 million. This cost is recognizable over the next 1.9 years, which is the weighted average contractual life. Roll-forward of Performance Share Units The following table summarizes the activity related to PSUs during 2020: Number of Weighted-Average Share Price Nonvested — January 1 206,949 $185.61 Granted 98,099 167.94 Change in performance multiplier 25,850 179.71 Vested (153,469) 187.24 Forfeited (7,442) 146.76 Nonvested — December 31 169,987 174.10 Cash-Settled Stock Appreciation Rights Cash-settled stock appreciation right awards ("SARs") give the holder the right, upon exercise, to receive in cash the difference between the market price per share of our ordinary shares at the time of exercise and the exercise price of the SARs. The exercise price of each SAR is equal to the market price of our ordinary shares on the date of the grant. Vested SARs are exercisable for periods not to exceed either 4 years or 10 years from the date of grant. We have not granted any new SARs since 2015. The following table summarizes the activity related to SARs during 2020: Number of SARs Weighted-Average Exercise Price of SARs Weighted-Average Expected Term (in years) Aggregate Intrinsic Value (1) Balance, beginning of year 89,227 $ 143.33 Exercised (12,793) 136.94 Balance, end of year 76,434 144.40 1.90 $ 4,623 (1) The aggregate intrinsic value is calculated as the pre-tax difference between the exercise price of the underlying share awards and the closing price per share of our ordinary shares of $204.89 on December 31, 2020. Compensation expense for SARs is based on the estimated fair value on the date of grant using the Black-Scholes valuation model, which requires the use of subjective assumptions related to the expected stock price volatility, expected term, expected dividend yield and risk-free interest rate. SARs are liability-classified awards for which compensation expense and the liability are re-measured using the then-current Black Scholes assumptions at each interim reporting date based upon the portion of the requisite service period rendered. There was no unrecognized compensation cost related to our SARs as of December 31, 2020. The following table sets forth the assumptions used to estimate the fair value of the SARs using the Black-Scholes option valuation model as of December 31, 2020, 2019 and 2018: 2020 2019 2018 Weighted-average fair value per SAR $ 78.47 $ 76.03 $ 45.85 Weighted-average volatility 49.43 % 19.75 % 18.94 % Weighted-average risk-free interest rate 0.15 % 1.64 % 2.72 % Dividend yield 0.00 % 0.00 % 0.00 % Joint Share Ownership Plan Under the JSOP, we have the ability to make equity awards to our U.K.-based staff through which a recipient acquires jointly held interests in a set number of our Voting Ordinary Shares together with the independent trustee of the EB Trust at fair market value, pursuant to the terms of a joint ownership agreement. Voting rights in respect of shares held in the EB Trust are contractually waived. Shares held in the EB Trust are classified as treasury shares. On January 21, 2020, a JSOP award comprising 565,630 underlying Voting Ordinary Shares was made to our Chief Executive Officer which cliff-vests after 3 years. The value of the award at vesting, if any, is determined based on the price of our Voting Ordinary Shares appreciating above a certain threshold between the date of grant and the vesting date. If the higher of the closing price per Share on January 20, 2023 and the 10-day volume weighted average price per Share for the ten by 565,630. If the Market Price is less than $266.00 on such date, the award will have no value. In addition, 20% of the award is subject to a performance condition based on growth in fully diluted book value per share between January 1, 2020 and December 31, 2022. The accounting for stock-settled JSOP awards is similar to options, whereby the grant date fair value of $13.6 million is expensed over the life of the award. To determine the grant date fair value of $24.13 per share, we utilized a Monte-Carlo valuation model with the following assumptions: 2020 Weighted-average volatility 18.66 % Weighted-average risk-free interest rate 1.55 % Dividend yield 0.00 % The unrecognized compensation cost related to our unvested JSOP share awards as of December 31, 2020 was $9.4 million. This cost is recognizable over the next 2.1 years, which is the weighted average contractual life. Northshore and Atrium Incentive Plans Our subsidiary, Northshore, had long-term incentive plans that award time-based restricted shares of Northshore to certain Atrium employees. Shares generally vested over two StarStone Incentive Plan Our subsidiary, StarStone, had long-term incentive plans that were cash-settled plans for StarStone employees. The awards were based on StarStone's performance over two Deferred Compensation and Ordinary Share Plan for Non-Employee Directors The number of units credited to the accounts of non-employee directors for the years ended December 31, 2020, 2019 and 2018 under the Enstar Group Limited Deferred Compensation and Ordinary Share Plan for Non-Employee Directors (the "Deferred Compensation Plan") were 7,204, 5,976 and 5,691, respectively. Employee Share Purchase Plan We provide an Employee Share Purchase Plan whereby eligible employees may purchase Enstar shares at a 15% discount to market price, in an amount of share value limited to the lower of $21,250 or 15% of the employee's base salary. The 15% discount is expensed as compensation cost. The number of shares issued to employees under the Employee Share Purchase Plan for the years ended December 31, 2020, 2019 and 2018 were 16,914, 15,269 and 14,183, respectively. Pension Plans We provide retirement benefits to eligible employees through various plans that we sponsor. Pension expense can be affected by changes in our employee headcount. The table below summarizes the expense related to our Defined Contribution Plans and our Defined Benefit Plan for the years ended December 31, 2020, 2019 and 2018. 2020 2019 2018 Defined contribution plans $ 11,791 $ 11,798 $ 11,434 Defined benefit plan 2,975 684 2,243 Total pension expense $ 14,766 $ 12,482 $ 13,677

Income Taxation

Income Taxation	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxation	20. INCOME TAXATION Enstar Group Limited is incorporated under the laws of Bermuda and under Bermuda law is not required to pay taxes in Bermuda based upon income or capital gains. The Company, under the Exempted Undertakings Tax Protection Act of 1966, is protected against any legislation that may be enacted in Bermuda which would impose any tax on profits, income, or gain until March 31, 2035. We have foreign operating subsidiaries and branch operations principally located in the United States, United Kingdom, Continental Europe and Australia that are subject to federal, foreign, state and local taxes in those jurisdictions. The undistributed earnings from our foreign subsidiaries will be indefinitely reinvested in those jurisdictions where the undistributed earnings were earned. Deferred tax liabilities have not been accrued with respect to the undistributed earnings of our foreign subsidiaries. Generally, when earnings are distributed as dividends, withholding taxes may be imposed by the jurisdiction of the paying subsidiary. For our U.S. subsidiaries, we have not currently accrued any withholding taxes with respect to unremitted earnings because, solely for U.S. Federal income tax purposes, there are no accumulated positive earnings and profits that could be subject to U.S. dividend withholding tax. For our United Kingdom subsidiaries, there are no withholding taxes imposed as a matter of UK domestic tax law. For our other foreign subsidiaries, an insignificant amount of earnings is indefinitely reinvested; however, it would not be practicable to compute the related amounts of withholding taxes due to a variety of factors, including the amount, timing and manner of any repatriation. Because we operate in many jurisdictions, our net earnings are subject to risk due to changing tax laws and tax rates around the world. The current, rapidly changing economic environment may increase the likelihood of substantial changes to tax laws in the jurisdictions in which we operate. Income Tax Expense The following table presents earnings (loss) before income taxes by jurisdiction attributable to continuing operations, including earnings from equity method investments, for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Domestic (Bermuda) $ 1,503,505 $ 576,338 $ (232,743) Foreign 231,444 356,878 15,293 Total earnings (loss) before income taxes attributable to continuing operations $ 1,734,949 $ 933,216 $ (217,450) The following table presents our current and deferred income tax expense (benefit) attributable to continuing operations by jurisdiction for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Current: Domestic (Bermuda) $ — $ — $ — Foreign 15,232 16,330 (917) 15,232 16,330 (917) Deferred: Domestic (Bermuda) — — — Foreign 8,595 (3,958) (2,772) 8,595 (3,958) (2,772) Total income tax expense (benefit) attributable to continuing operations $ 23,827 $ 12,372 $ (3,689) The actual effective income tax rate differs from the statutory rate of 0 percent under Bermuda law to earnings (loss) attributable to continuing operations before income taxes, including earnings (loss) from equity method investments for the years ended December 31, 2020, 2019 and 2018 as shown in the following reconciliation: 2020 2019 2018 Earnings (loss) before income taxes $ 1,734,949 $ 933,216 $ (217,450) Bermuda income taxes at statutory rate 0.0 % 0.0 % 0.0 % Foreign income tax rate differential 1.2 % 8.6 % 0.6 % Change in valuation allowance 0.1 % (7.2) % (1.8) % U.S. base erosion and anti-abuse tax — % 0.3 % (0.3) % Other 0.1 % (0.4) % 3.2 % Effective tax rate 1.4 % 1.3 % 1.7 % Our effective tax rate is generally driven by the geographical distribution of our pre-tax earnings between our taxable and non-taxable jurisdictions. Deferred Tax Assets and Liabilities Deferred tax assets and liabilities (included in other assets and other liabilities, respectively, on the consolidated balance sheet) reflect the tax effect of the differences between the financial statement carrying amount and the income tax bases of assets and liabilities. Significant components of the deferred tax assets and deferred tax liabilities as of December 31, 2020 and 2019 were as follows: 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 141,459 $ 144,609 Insurance reserves 22,238 7,535 Unearned premiums 68 151 Provisions for bad debt 407 6,172 Defendant asbestos and environmental liabilities 121,006 140,000 Other deferred tax assets 16,696 3,230 Deferred tax assets 301,874 301,697 Valuation allowance (118,229) (117,390) Deferred tax assets, net of valuation allowance 183,645 184,307 Deferred tax liabilities: Unrealized gains on investments (20,185) (14,079) Lloyd's underwriting profit taxable in future periods (15,555) (8,852) Deferred policy acquisition cost — (8,267) Other deferred tax liabilities (9,242) (13,390) Deferred tax liabilities (44,982) (44,588) Net deferred tax asset $ 138,663 $ 139,719 Net Deferred Tax Asset (Liability) Balance by Major Jurisdiction: December 31, 2020 2019 Net Deferred Tax Net Deferred Tax United States $ 156,730 $ 154,700 United Kingdom (18,095) (16,074) Other 28 1,093 Total $ 138,663 $ 139,719 Net Operating Loss Carryforwards: As of December 31, 2020, we had net operating loss carryforwards that could be available to offset future taxable income, as follows: Tax Jurisdiction Loss Carryforwards Tax effect Expiration Operating and Capital Loss Carryforwards: United States - Net operating loss $ 428,732 $ 90,034 2024-2038 United Kingdom 185,230 35,194 Indefinitely Luxembourg 17,200 4,300 2035-2036 Other 48,683 11,931 Indefinitely The U.S. and UK net operating loss carryforwards are also subject to certain utilization limitations and have been considered in management's assessment of Valuation Allowance. Assessment of Valuation Allowance on Deferred Tax Assets As of December 31, 2020 and 2019, we had deferred tax asset valuation allowances of $118.2 million and $117.4 million, respectively, related to foreign subsidiaries. We recorded a net increase of $0.8 million in our deferred tax valuation allowance primarily due to a change in deferred tax assets which management does not believe meet the "more likely than not" realization standard. The realization of deferred tax assets is dependent on generating sufficient taxable income in future periods in which the tax benefits are deductible or creditable. The amount of the deferred tax asset considered realizable, however, could be revised in the future if estimates of future taxable income change. Income taxes are determined and assessed jurisdictionally by legal entity or by filing group. Certain jurisdictions require or allow combined or consolidated tax filings. We have estimated future taxable income of our foreign subsidiaries and provided a valuation allowance in respect of those assets where we do not expect to realize a benefit. We have considered all available evidence using a “more likely than not” standard in determining the amount of the valuation allowance. We considered the following evidence: (i) net earnings or losses in recent years; (ii) the future sustainability and likelihood of positive net earnings of our subsidiaries; (iii) the carryforward periods of tax losses including the effect of reversing temporary differences; and (iv) tax planning strategies, in making our determination. The assumptions used in determining future taxable income require significant judgment and any changes in these assumptions could have an impact on earnings. Unrecognized Tax Benefits During the years ended December 31, 2020, 2019 and 2018, there were no unrecognized tax benefits. There were no accruals for the payment of interest and penalties related to unrecognized tax benefits as of each of December 31, 2020, 2019 and 2018. Open Tax Years Our operating subsidiaries may be subject to audit by various tax authorities and may have different statutes of limitations expiration dates. Tax authorities may propose adjustments to our income taxes. Listed below are the tax years that remain subject to examination by a major tax jurisdiction as of December 31, 2020: Major Tax Jurisdiction Open Tax Years United States 2017-2020 United Kingdom 2019-2020 Australia 2015-2020

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions	21. RELATED PARTY TRANSACTIONSStone Point Capital LLCThrough several private transactions occurring from May 2012 to July 2012 and an additional private transaction that closed in May 2018, investment funds managed by Stone Point Capital LLC ("Stone Point") have acquired an aggregate of 1,635,986 of our Voting Ordinary Shares (which constitutes 8.8% of our outstanding Voting Ordinary Shares). On November 6, 2013, we appointed James D. Carey to our Board of Directors. Mr. Carey is the sole member of an entity that is one of four general partners of the entities serving as general partners for Trident, is a member of the investment committees of such general partners, and is a member and senior principal of Stone Point, the manager of the Trident funds. On November 30, 2020, we completed the sale and recapitalization of StarStone U.S. to Core Specialty in a transaction described in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations". Pursuant to the terms of a Recapitalization Agreement entered into on August 13, 2020 among us, the Trident V Funds, which are advised by Stone Point, and the Dowling Funds (the "Recapitalization Agreement"), we agreed to exchange a portion of our indirect interest in Northshore, the holding company that owns Atrium and Arden, for all of the Trident V Funds’ indirect interest in StarStone U.S. (the “Exchange Transaction”), which is described in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations." Our interests in StarStone and Atrium are held through North Bay, which is a joint venture between us, the Trident V Funds and the Dowling Funds. As of December 31, 2020, we had an indirect 59.0% interest in North Bay and the Trident V Funds and the Dowling Funds owned 39.3% and 1.7%, respectively. North Bay owned 100% of StarStone Specialty Holdings Limited ("SSHL"), the holding company for the StarStone group, which included StarStone U.S. and StarStone International. North Bay also owned 92% of Northshore. North Bay also owns the preferred equity of three segregated cells within our wholly-owned subsidiary Fitzwilliam Insurance Limited (the “Fitzwilliam Cells”) that have provided reinsurance to StarStone and are considered part of StarStone International. Following the completion of the sale and recapitalization of StarStone U.S. and the Exchange Transaction, we now own 25.23% of Core Specialty on a fully diluted basis, which owns StarStone U.S., and 13.8% of Northshore, which continues to own Atrium and Arden. The Trident V Funds own 76.3% of Northshore, and the Dowling Funds own 0.4% of Core Specialty and 1.6% of Northshore. The Exchange Transaction had no impact on the ultimate ownership of SSHL, which continues to own StarStone International, with us, the Trident V Funds and the Dowling Funds retaining our and their prior ownership interests in SSHL of 59.0%, 39.3% and 1.7%, respectively. In connection with the closing of the Exchange Transaction, we entered into amended and restated shareholders’ agreements with the Trident V Funds and the Dowling Funds with respect to our investment in SSHL and Northshore. With respect to SSHL, we have the right to designate three of five members of the SSHL board of directors and the Trident V Funds have the right to designate the other two members. The Trident V Funds also have certain customary rights as a minority shareholder to approve certain material matters and transactions. Each shareholder of SSHL must provide us and the Trident V Funds with a right of first offer to acquire its shares in SSHL if such shareholder wishes to sell them. Each shareholder will also have certain rights to participate in sales of SSHL shares by the other shareholders, and we have certain rights to cause the Trident V Funds and the Dowling Funds to sell their SSHL shares if we wish to sell control of SSHL or the StarStone International business. Also pursuant to the terms of the shareholders’ agreement for SSHL, at any time after December 31, 2022, the Trident V Funds have the right to cause us to purchase their shares in SSHL at their fair market value, and the Dowling Funds have the right to participate in any such sale transaction initiated by the Trident V Funds. We would be entitled to pay the purchase price for such SSHL shares in cash or in unrestricted ordinary shares of Enstar that are then listed or admitted to trading on a national securities exchange. At any time after March 31, 2023, we will have the right to cause the Trident V Funds and the Dowling Funds to sell their shares in SSHL to us at their fair market value. We would be obligated to pay the purchase price for such SSHL shares in cash. Pursuant to the terms of the shareholders’ agreement for Northshore, for so long as we own 50% or more of the Northshore shares we held upon the closing of the Exchange Transaction, we have the right to designate one member to the board of directors of Northshore and each of its material subsidiaries. Our shares in Northshore are subject to an 18-month restriction on transfer following the closing of the Exchange Transaction, after which the Trident V Funds have a right of first offer to acquire our shares in Northshore if we wish to sell them. We have certain rights to participate in sales of Northshore shares by the Trident V Funds, and the Trident V Funds have certain rights to cause us to sell our Northshore shares if the Trident V Funds wish to sell control of Northshore or the Atrium business. We, in partnership with StarStone's other shareholders, have previously completed transactions to provide capital support to StarStone in the form of: (i) a contribution to its contributed surplus account and a loss portfolio transfer, effective October 1, 2018. To fund the transaction, the North Bay shareholders contributed an aggregate amount of $135.0 million to North Bay in proportion to their ownership interests. Trident’s proportionate contribution of $53.1 million was temporarily funded by North Bay and was reimbursed in the first quarter of 2019; and (ii) a loss portfolio transfer, effective April 1, 2019, for which shareholders agreed to contribute an aggregate amount of $48.0 million. In addition, Enstar has separately entered into a loss portfolio transfer and adverse development cover with StarStone effective October 1, 2019, whereby StarStone transferred $189.4 million in loss reserves and unearned premium to a wholly-owned Enstar subsidiary in exchange for premium of $189.4 million. Enstar also provided an additional $59.0 million adverse development cover in excess of the $189.4 million. As of December 31, 2020 and December 31, 2019, the RNCI on our balance sheet relating to these Trident co-investment transactions was $350.2 million and $420.5 million, respectively. As of December 31, 2020, we had the following additional relationships with Stone Point and its affiliates: • Investments in funds (carried within other investments) managed by Stone Point, with respect to which we recognized net unrealized gains (losses); • Investments in registered investment companies affiliated with entities owned by Trident or otherwise affiliated with Stone Point, with respect to which we recognized net unrealized gains (losses) and interest income; • Separate accounts managed by Eagle Point Credit Management, PRIMA Capital Advisors and SKY Harbor Capital Management, which are affiliates of entities owned by Trident, with respect to which we incurred management fees; • Investments in funds (carried within other investments) managed by Sound Point Capital, an entity in which Mr. Carey has an indirect minority ownership interest and serves as a director, with respect to which we recognized net unrealized gains (losses); • Sound Point Capital has acted as collateral manager for certain of our direct investments in CLO debt and equity securities, with respect to which we recognized net unrealized gains (losses) and interest income; • Marble Point Capital, which is an affiliate of an entity owned by Trident, has acted as collateral manager for certain of our direct investments in CLO debt and equity securities, with respect to which we recognized net unrealized gains (losses) and interest income; • A separate account managed by Sound Point Capital, with respect to which we incurred management fees in prior periods; • In the fourth quarter of 2018, we invested $25.0 million in Mitchell TopCo Holdings, the parent company of Mitchell International and Genex Services, as a co-investor alongside certain Trident funds; and • In the second quarter of 2020, we invested $10.0 million in a 2 year senior secured unrated floating rate term loan facility with an extension option which was arranged and managed by Sound Point Capital. The facility's borrower, Amplify U.S. Inc., is a subsidiary of Evergreen (as defined below) and has used the proceeds to purchase AmTrust's preferred stock. The facility ranks senior to all other claims of the borrower, the purchased preferred stock and cash flows therefrom serve as collateral, and AmTrust has provided an unsecured guarantee for the facility. For further information on our relationships with Evergreen and AmTrust, refer to the AmTrust section below. The following table presents the amounts included in our consolidated balance sheet related to our related party transactions with Stone Point and its affiliated entities: December 31, 2020 December 31, 2019 Short-term investments, AFS, at fair value $ 878 $ 1,431 Fixed maturities, trading, at fair value 196,086 269,131 Fixed maturities, AFS, at fair value 227,397 160,303 Equities, at fair value 103,914 121,794 Other investments, at fair value: Hedge funds 19,844 18,993 Fixed income funds 210,017 381,449 Private equity funds 37,262 34,858 CLO equities 38,658 32,560 CLO equity funds 166,523 87,509 Private Debt 27,016 16,312 Real estate fund 27,278 18,106 Total investments 1,054,873 1,142,446 Cash and cash equivalents 23,933 54,080 Other assets 403 10 Other liabilities 745 4,710 Net investment $ 1,078,464 $ 1,191,826 The following table presents the amounts included in net earnings related to our related party transactions with Stone Point and its affiliated entities: 2020 2019 2018 Net investment income $ 16,325 $ 8,733 $ 7,424 Net realized and unrealized gains (losses) 23,750 26,631 207 Total net earnings $ 40,075 $ 35,364 $ 7,631 On December 15, 2016, KaylaRe completed an initial capital raise of $620.0 million. We originally owned 48.2% of KaylaRe's common shares and recorded our investment in KaylaRe using the equity method basis of accounting, pursuant to the conclusion that we were not required to consolidate following an analysis based on the guidance in ASC 810 - Consolidation . On May 14, 2018, we completed a transaction to acquire all of the outstanding shares and warrants of KaylaRe, following the receipt of all required regulatory approvals. In consideration for the acquired shares and warrants of KaylaRe, we issued an aggregate of 2,007,017 ordinary shares, comprising 1,501,778 voting ordinary shares and 505,239 Series E non-voting ordinary shares to the shareholders of KaylaRe as follows: (i) 1,204,353 voting ordinary shares and 505,239 Series E Shares to a fund managed by Hillhouse Capital Management, Ltd.; (ii) 285,986 voting ordinary shares to Trident; and (iii) 11,439 voting ordinary shares to the minority shareholder. In addition, the Shareholders Agreement between Enstar and the other KaylaRe shareholders was effectively terminated. Effective May 14, 2018 we consolidated KaylaRe into our consolidated financial statements and any balances between KaylaRe and Enstar are now eliminated on consolidation. Refer to Note 3 - "Business Acquisitions" for additional information. Effective September 30, 2019, KaylaRe and KaylaRe Ltd. merged with Cavello Bay Reinsurance Limited, a wholly-owned subsidiary of the Company, with Cavello Bay Reinsurance Limited as the surviving company. Our consolidated statement of earnings for the year ended December 31, 2018 included the following balances related to transactions between us and KaylaRe and KaylaRe Ltd. up until May 14, 2018, the date of acquisition: 2018 Fee income due to Enstar Limited $ 1,453 Transactions under KaylaRe-StarStone QS: Ceded premium earned (52,651) Net incurred losses 31,654 Acquisition costs 18,774 Total net earnings (loss) $ (770) We have made significant direct investments in funds (the "Hillhouse Funds") managed by Hillhouse Capital Management, Ltd. and Hillhouse Capital Advisors, Ltd. (together, "Hillhouse Capital") and AnglePoint Asset Management Ltd., an affiliate of Hillhouse Capital ("AnglePoint"). As of December 31, 2020, the carrying value (i.e., the net asset value) of our direct investment in the InRe Fund, L.P. (the "InRe Fund"), which is managed by AnglePoint, was $2.4 billion (December 31, 2019: $918.6 million). The growth in the fund for the year ended December 31, 2020 was generated by significant unrealized investment gains during the year and an increase in our subscription to the fund of $300.0 million in June 2020. The InRe Fund qualifies as a variable interest entity and our maximum exposure to loss is the amount of our investment in the fund, as disclosed in the table below. As of December 31, 2020, the InRe Fund's assets were invested (5)% in net short fixed income securities, 20% in North American equities, 67% in international equities and 18% in financing, derivatives and other items. The derivatives in the InRe Fund are used for both hedging and investment purposes. The InRe Fund utilizes prime brokerage borrowing facilities and has also securitized certain letters of credit relating to intragroup reinsurances. We do not provide any financial support to the InRe Fund. Funds that employ leverage through borrowings and derivatives can generate outsized returns but can also experience greater levels of volatility. As of December 31, 2020 and 2019, our equity method investee, Enhanzed Re, had investments in a fund managed by AnglePoint, as set forth in the table below. Our consolidated balance sheet as of December 31, 2020 and 2019 included the following balances related to transactions with Hillhouse Capital and AnglePoint (as applicable): 2020 2019 Investments in funds managed by AnglePoint, held by Enhanzed Re $ 851,435 $ 327,799 Our ownership percentage of Enhanzed Re 47.4 % 47.4 % Our share of investments in funds managed by AnglePoint held by Enhanzed Re (through our equity method investment ownership) $ 403,580 $ 155,377 Investment in other funds managed by AnglePoint and Hillhouse: InRe Fund $ 2,365,158 $ 918,633 Other funds 369,508 232,968 $ 2,734,666 $ 1,151,601 We incurred management and performance fees of $394.0 million, which is deducted from the Hillhouse Funds' reported NAV, for the year ended December 31, 2020 in relation to the investment in funds managed by Hillhouse Capital and AnglePoint as described above. On February 21, 2021, we entered into a Termination and Release Agreement with InRe Fund, Hillhouse Capital, AnglePoint, and certain of their affiliates to terminate certain relationships, primarily with respect to InRe Fund, and to work collaboratively to effectuate the smooth transition of these changes. Pursuant to the Termination and Release Agreement, AnglePoint will cease to serve as the InRe Fund's investment manager on or prior to April 1, 2021 in connection with the intended purchase of AnglePoint’s Hong Kong affiliate (“AnglePoint HK”) by us or our designee from affiliates of Hillhouse Capital. As part of those transactions, AnglePoint will assign its investment management agreement with InRe Fund to AnglePoint HK. In connection with AnglePoint ceasing to serve as investment manager, affiliates of Hillhouse Capital agreed to a deduction of $100.0 million from amounts due to them from the InRe Fund and to waive their right to receive any performance fees that could have been earned for 2021. The Agreement also includes mutual releases of certain liabilities and obligations between Enstar and its affiliates on the one hand and Hillhouse and its affiliates on the other hand. In the first quarter of 2021, as a result of the Termination and Release Agreement, we will re-evaluate our conclusions with regard to consolidation of the InRe Fund in accordance with the accounting for variable interest entities. Monument Insurance Group Limited ("Monument Re") was established in October 2016 and Enstar has invested a total of $59.6 million in the common and preferred shares of Monument Re as of December 31, 2020 (December 31, 2019: $26.6 million). We own 20% of the common shares of Monument Re, as well as different classes of preferred shares which have fixed dividend yields, and which collectively represented a total economic interest of 23.0% as of December 31, 2020 (December 31, 2019: 23.5%). In connection with our investment in Monument Re, we entered into a Shareholders Agreement with the other shareholders and have accounted for our equity interest in Monument Re as an equity method investment since we have significant influence over its operating and financial policies. On May 31, 2019, we completed the transfer of our remaining life assurance policies written by our wholly-owned subsidiary Alpha Insurance SA to a subsidiary of Monument Re. In this transaction, we transferred policy benefits for life and annuity contracts with a carrying value of €88.8 million (or $99.1 million) and total assets with a fair value of €91.1 million (or $101.6 million) to a subsidiary of Monument Re. Our investment in the common and preferred shares of Monument Re, which is included in equity method investments on our consolidated balance sheet, as of December 31, 2020 and 2019 was $193.7 million and $60.6 million, respectively. During the twelve months ended December 31, 2020 and 2019 our share of net earnings on our investment in Monument Re was $88.3 million and $19.8 million, respectively. In addition, we received director fees from Monument Re of less than $0.1 million in connection with one of our representatives serving on Monument Re's board of directors during the twelve months ended December 31, 2020. Effective January 1, 2017, we sold SeaBright Insurance Company (“SeaBright Insurance”) to Clear Spring PC Acquisition Corp., a subsidiary of Delaware Life Insurance Company ("Delaware Life"). Following the sale, SeaBright Insurance was capitalized with $56.0 million of equity, with Enstar retaining a 20% indirect equity interest in SeaBright Insurance. Subsequently, SeaBright Insurance was renamed Clear Spring Property and Casualty Company ("Clear Spring"). Effective December 30, 2020, we sold our remaining interest in Clear Spring to Delaware Life for $12.2 million and recorded a gain on sale of $0.6 million in the fourth quarter of 2020. As a result, Clear Spring was not a related party as of December 31, 2020. Prior to the sale, we accounted for our equity interest in Clear Spring as an equity method investment as we had significant influence over its operating and financial policies. Our investment in the common shares of Clear Spring which is included in equity method investments on our consolidated balance sheet, as of December 31, 2020 and 2019 was $0 and $10.6 million, respectively. During the twelve months ended December 31, 2020 and 2019 our share of net earnings on our investment in Clear Spring was $1.0 million and $0.6 million, respectively. Effective January 1, 2017, StarStone National Insurance Company (“StarStone National”) entered into a ceding quota share treaty with Clear Spring pursuant to which Clear Spring reinsures 33.3% of core workers' compensation business written by StarStone National. This agreement was terminated as of December 31, 2018. Effective January 1, 2017, we also entered into an assuming quota share treaty with Clear Spring pursuant to which an Enstar subsidiary reinsures 25% of all workers' compensation business written by Clear Spring. This is recorded as other activities. As noted above, Clear Spring was not a related party as of December 31, 2020. Our consolidated balance sheet as of December 31, 2019 included the following balances between us and Clear Spring: 2019 Balances under StarStone ceding quota share included, in assets or liabilities held-for-sale: Reinsurance balances recoverable on paid and unpaid losses $ 22,812 Prepaid insurance premiums 51 Ceded payable 3,616 Ceded acquisition costs 21 Balances under assuming quota share: Losses and LAE 6,135 Unearned reinsurance premiums 13 Funds held 8,611 Our consolidated statement of earnings for the years ended December 31, 2020, 2019 and 2018 included the following amounts between us and Clear Spring: 2020 2019 2018 Transactions under StarStone ceding quota share, included in net earnings (loss) from discontinued operations: Ceded premium earned $ 122 $ (14,994) (29,520) Net incurred losses and LAE 2,730 6,567 18,143 Acquisition costs 56 356 7,035 Transactions under assuming quota share: Premium earned (15) 3,749 7,380 Net incurred losses and LAE 1,014 (2,202) (4,536) Acquisition costs 11 (92) (1,836) Total net earnings (loss) $ 3,918 $ (6,616) $ (3,334) The following table presents the amounts included in net earnings related to our related party transactions with AmTrust: 2020 2019 2018 Net investment income $ 7,365 $ 7,667 $ 299 Net realized and unrealized gains (11,183) 10,086 — Total net earnings $ (3,818) $ 17,753 $ 299 In June 2018, we made a $50.0 million indirect investment in the shares of Citco III Limited ("Citco"), a fund administrator with global operations. As of December 31, 2020, we owned 31.9% of the common shares in HH CTCO Holdings Limited, which in turn owns 15.4% of the convertible preferred shares, amounting to a 6.2% interest in the total equity of Citco. Pursuant to an investment agreement and in consideration for participation therein, a related party of Hillhouse Capital provided us with investment support. In a private transaction that preceded our co-investment opportunity, certain Citco shareholders, including Trident, agreed to sell all or a portion of their interests in Citco. As of December 31, 2020, Trident owned 3.4% interest in Citco. Mr. Carey currently serves as an observer to the board of directors of Citco in connection with Trident's investment therein. Our indirect investment in the shares of Citco, which is included in equity method investments on our consolidated balance sheet, as of December 31, 2020 and 2019 was $53.0 million and $51.7 million, respectively. During the twelve months ended December 31, 2020 and 2019 our share of net earnings on our indirect investment in Citco was $2.2 million and $2.7 million, respectively. Enhanzed Re is a joint venture between Enstar, Allianz SE ("Allianz") and Hillhouse Capital that was capitalized in December 2018. Enhanzed Re is a Bermuda-based Class 4 and Class E reinsurer and will reinsure life, Non-life Run-off, and property and casualty insurance business, initially sourced from Allianz and Enstar. Enstar, Allianz and Hillhouse Capital affiliates have made equity investment commitments in the aggregate of $470.0 million to Enhanzed Re. Enstar owns 47.4% of the entity, Allianz owns 24.9%, and an affiliate of Hillhouse Capital owns 27.7%. As of December 31, 2020, Enstar contributed $154.1 million of its total capital commitment to Enhanzed Re and had an uncalled amount of $68.7 million. We have accounted for our equity interest in Enhanzed Re as an equity method investment as we have significant influence over its operating and financial policies. Enstar acts as the (re)insurance manager for Enhanzed Re, for which it receives fee income recorded within fees and commission income, AnglePoint acts as the primary investment manager, and an affiliate of Allianz provides investment management services. Enhanzed Re writes business from affiliates of its operating sponsors, Allianz SE and Enstar. It also underwrites other business to maximize diversification by risk and geography. Our investment in the common shares of Enhanzed Re, which is included in equity method investments on our consolidated balance sheet, as of December 31, 2020 and 2019 was $330.3 million and $182.9 million, respectively. During the twelve months ended December 31, 2020 and 2019 our share of net earnings on our investment in Enhanzed Re was $147.3 million and $28.9 million, respectively. We have ceded 10% of the Zurich and AXA transactions, as discussed in Note 4 - "Significant New Business," to Enhanzed Re on the same terms and conditions as those received by Enstar. During the year ended December 31, 2020, one of our UK-based Non-life Run-off subsidiaries ceded $137.0 million of net loss reserves to Enhanzed Re. The reinsurance is on a funds held basis with fixed crediting rates. Our consolidated balance sheet as of December 31, 2020 and 2019 included the following balances between us and Enhanzed Re: 2020 2019 Balances under ceding quota share: Reinsurance balances recoverable $ 208,379 $ 59,601 Funds held 193,981 50,089 Insurance balances payables 1,276 1,443 Other assets 730 1,033 Our consolidated statement of earnings for the years ended December 31, 2020 and 2019 included the following amounts between us and Enhanzed Re: 2020 2019 Amounts under ceding quota share: Ceded premium earned $ (391) $ — Net incurred losses and LAE (5,977) — Acquisition costs 169 73 Net investment income (4,272) — Net realized and unrealized gains (740) — Other income 2,617 — Fees and commission income 572 749 Total Net earnings $ (8,022) $ 822 Change in unrealized gains (losses) on AFS investments $ (2,729) $ — Core Specialty Following the sale and recapitalization of StarStone U.S. as described in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations," our investment in the common shares of Core Specialty, which is included in equity method investments on our consolidated balance sheet was $235.0 million as of December 31, 2020. In connection with the sale and recapitalization of StarStone U.S. we entered into an LPT and ADC reinsurance agreement with respect to StarStone U.S.’ legacy reserves. Concurrent with the closing of the LPT and ADC reinsurance agreement, we entered into an ASA with StarStone U.S., through which one of our wholly-owned subsidiaries was appointed as an independent contractor to provide certain administrative services covering the business we assumed from StarStone U.S. through the LPT and ADC reinsurance agreement. In addition, concurrent with the sale of StarStone U.S. to Core Specialty, one of our wholly-owned subsidiaries entered into a TSA with Core Specialty through which our subsidiary and Core Specialty agreed to provide certain transitional services to each other relating to the StarStone U.S. businesses, for a specified period of time. On completion of the sale and recapitalization of StarStone U.S. on November 30, 2020, we received $235.0 million of Core Specialty shares and $51.5 million of cash. Subsequently, the cash component of the consideration has been determined to be $47.0 million. The surplus of $4.5 million is repayable to Core Specialty and is recorded within other liabilities. Furthermore, there are existing reinsurance agreements whereby (i) certain of our subsidiaries provide reinsurance protection to StarStone U.S. ("the assuming reinsurances") and (ii) StarStone U.S. provides reinsurance protection to certain of our subsidiaries ("the ceding reinsurances"). These arrangements remain in place. Our consolidated balance sheet as of December 31, 2020 included the following balances between us and Core Specialty: 2020 Balances under assuming quota share, LPT and ADC reinsurances: Funds held by reinsured companies $ 58,086 Other assets 38,846 Losses and loss adjustment expenses 682,637 Insurance and reinsurance balances payable 24,806 Other liabilities 5,003 Balances under ceding reinsurances: Reinsurance balances recoverable on paid and unpaid losses 1,736 Balances under service agreements: Other assets 6,727 Other liabilities 328 Balances under sale and recapitalization agreement: Other liabilities 4,512 Our consolidated statement of earnings for the year ended December 31, 2020 included the following amounts between us and Core Specialty: 2020 Transactions under assuming quota share, LPT and ADC reinsurances: Net premiums earned $ 76 Net incurred losses and loss adjustment expenses (1,223) Acquisition costs 458 Transactions under service agreements: Fees and commission income 4,004 Total net earnings $ 3,315

Dividend Restrictions and Statu

Dividend Restrictions and Statutory Financial Information	12 Months Ended
	Dec. 31, 2020
Insurance [Abstract]
Dividend Restrictions and Statutory Financial Information	22. DIVIDEND RESTRICTIONS AND STATUTORY FINANCIAL INFORMATION Parent Company Dividend Restrictions There were no significant restrictions on the Parent Company's ability to pay dividends from retained earnings as of December 31, 2020. Bermuda law permits the payment of dividends if (i) we are not, or would not be after payment, unable to pay our liabilities as they become due and (ii) the realizable value of our assets is in excess of our liabilities after taking such payment into account. We have not historically declared a dividend on our ordinary shares. The issuance of our Series D and E Preferred Shares have resulted in the declaration of dividends. Holders of Series D and Series E Preferred Shares are entitled to receive, only when, as and if declared, non-cumulative cash dividends, paid quarterly in arrears on the 1st day of March, June, September and December of each year of 7.0% per annum. Refer to Note 17 - "Shareholders' Equity" for details regarding dividends on preferred shares. The Bermuda Monetary Authority ("BMA") acts as group supervisor to Enstar. On an annual basis, we are required to file group statutory financial statements, a group statutory financial return, a group capital and solvency return, audited group financial statements and a Group Solvency Self-Assessment ("GSSA") with the BMA. The GSSA is designed to document our perspective on the capital resources necessary to achieve our business strategies and remain solvent, and to provide the BMA with insights on our risk management, governance procedures and documentation related to this process. We are required to maintain available group statutory capital and surplus in an amount that is at least equal to the group enhanced capital requirement ("Group ECR"). The BMA has also established a group target capital level equal to 120% of the Group ECR. We are in compliance with these requirements. Our ability to pay dividends to our shareholders is dependent upon the ability of our (re)insurance subsidiaries to distribute capital and pay dividends to us. Our (re)insurance subsidiaries are subject to certain regulatory restrictions on the distribution of capital and payment of dividends in the jurisdictions in which they operate, as described below. The restrictions are generally based on net income or levels of capital and surplus as determined in accordance with the relevant statutory accounting practices. Failure of these subsidiaries to meet their applicable regulatory requirements could result in restrictions on any distributions of capital or retained earnings or stricter regulatory oversight of the subsidiaries. Our ability to pay dividends and make other forms of distributions may also be limited by repayment obligations and financial covenants in our outstanding loan facility agreements. Subsidiary Statutory Financial Information and Dividend Restrictions Our (re)insurance subsidiaries prepare their statutory financial statements in accordance with statutory accounting practices prescribed or permitted by local regulators. Statutory and local accounting differs from U.S. GAAP, including in the treatment of investments, acquisition costs and deferred income taxes, amongst other items. The statutory capital and surplus amounts for the years ended December 31, 2020 and 2019 and statutory net income amounts for the years ended December 31, 2020, 2019 and 2018 for our (re)insurance subsidiaries based in Bermuda, the United Kingdom, Australia, the United States and Continental Europe are summarized in the table below which includes information relating to acquisitions from the year of acquisition: Statutory Capital and Surplus Required Actual Statutory Income 2020 2019 2020 2019 2020 2019 2018 Bermuda $ 2,711,687 $ 2,138,395 $ 5,565,429 $ 4,016,663 $ 1,850,913 $ 643,683 $ 29,486 U.K. 803,685 837,104 1,224,208 1,532,751 43,219 154,644 (52,936) U.S. 185,904 364,507 554,339 861,379 (67,477) 121,406 (75,005) Europe 95,746 94,334 214,115 229,344 (983) 11,816 (17,611) Australia 18,858 18,110 58,531 37,815 (1,722) 4,847 1,761 As of December 31, 2020, the total amount of net assets of our consolidated subsidiaries that were restricted was $3.8 billion. Certain material aspects of these laws and regulations as they relate to solvency, dividends and capital and surplus are summarized below. Bermuda Our Bermuda-based (re)insurance subsidiaries are registered under the Insurance Act 1978 of Bermuda and related regulations, as amended (the "Insurance Act"). The Insurance Act imposes certain solvency and liquidity standards and auditing and reporting requirements and grants the BMA powers to supervise, investigate, require information and the production of documents and intervene in the affairs of insurance companies. The Insurance Act requires that our Bermuda-based (re)insurance subsidiaries maintain certain solvency and liquidity standards. The minimum liquidity ratio requires that the value of relevant assets not be less than 75% of the amount of relevant liabilities. The minimum solvency margin, which varies depending on the class of the insurer, is determined as a percentage of either net reserves for losses and LAE or premiums. Our Bermuda subsidiaries with commercial insurance licenses are required to maintain a minimum statutory capital and surplus (Enhanced Capital Requirement or "ECR") at least equal to the greater of a minimum solvency margin or the Bermuda Solvency Capital Requirement ("BSCR"). The BSCR is calculated based on a standardized risk-based capital model as provided by the BMA. Each of our regulated Bermuda subsidiaries would be prohibited from declaring or paying any dividends if it were in breach of its minimum solvency margin or liquidity ratio or if the declaration or payment of such dividends would cause it to fail to meet such margin or ratio. In addition, each of our regulated Bermuda subsidiaries is prohibited, without the prior approval of the BMA, from reducing by 15% or more its total statutory capital, or from reducing by 25% of more its total statutory capital and surplus, as set out in its previous year’s statutory financial statements. Our Bermuda insurance companies that are in run-off are required to seek BMA approval for any dividends or distributions. As of December 31, 2020 and 2019, each of our Bermuda-based (re)insurance subsidiaries exceeded their respective minimum solvency and liquidity requirements. The Bermuda (re)insurance subsidiaries in aggregate exceeded minimum solvency requirements by $2.9 billion as of December 31, 2020 (2019: $1.9 billion) and were in compliance with their liquidity requirements. U.K. Insurance Companies (non-Lloyd's) Our U.K. based insurance subsidiaries are regulated by the U.K. Prudential Regulatory Authority (the "PRA") and the Financial Conduct Authority (the "FCA", together with the PRA, the "U.K. Regulator"). Our U.K.-based insurance subsidiaries are required to maintain adequate financial resources in accordance with the requirements of the U.K. Regulator. Insurers must comply with a Solvency Capital Requirement ("SCR"), which is calculated using either the Solvency II standard formula or a bespoke internal model. Our non-Lloyd's U.K. companies use the standard formula for determining compliance with the SCR. The calculation of the minimum capital resources requirements in any particular case depends on, among other things, the type and amount of insurance business written and claims paid by the insurance company. As of December 31, 2020 and 2019, all of our U.K. insurance subsidiaries maintained capital in excess of the minimum capital resources requirements and complied with the relevant U.K. Regulator requirements. Our U.K.-based insurance subsidiaries, including our Lloyd's Syndicates described below, in aggregate, maintained capital in excess of the minimum capital resources requirements by $420.5 million and $695.6 million as of December 31, 2020 and 2019, respectively. The U.K. Regulator’s rules require our U.K. insurance subsidiaries to obtain regulatory approval for any proposed or actual payment of a dividend. The U.K. Regulator uses the SCR, among other tests, when assessing requests to make distributions. Lloyd’s As of December 31, 2020, we participated in the Lloyd’s market through our interests in: (i) Atrium’s Syndicate 609, which is managed by Atrium Underwriters Limited, a Lloyd's managing agent; (ii) StarStone’s Syndicate 1301, which is managed by StarStone Underwriting Limited ("SUL"), a Lloyd’s managing agent; and (iii) Syndicate 2008, a wholly aligned syndicate that has permission to underwrite RITC business and other run-off or discontinued business type transactions with other Lloyd’s syndicates. We participated on each of the three syndicates through a single, wholly owned Lloyd’s corporate member. SUL serves as managing agent for Syndicate 2008. On November 17, 2020, we announced an agreement to sell SUL, together with the right to operate StarStone's Syndicate 1301; and on January 1, 2021, we sold the Atrium business. These transactions are discussed further in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations." The underwriting capacity of a member of Lloyd’s is supported by providing Funds at Lloyd’s, as described in Note 6 - "Investments". Business plans, including maximum underwriting capacity, for Lloyd’s syndicates requires annual approval by the Lloyd’s Franchise Board, which may require changes to any business plan or additional capital to support underwriting plans. The Lloyd’s market has applied the Solvency II internal model under Lloyd’s supervision, and our Lloyd’s operations are required to meet Solvency II standards. Lloyd's has the approval of the PRA to use its internal model under the Solvency II regime. United States Our U.S. Non-life Run-off (re)insurance subsidiaries are subject to the insurance laws and regulations of the states in which they are domiciled, licensed and/or eligible to conduct business. These laws restrict the amount of dividends the subsidiaries can pay to us. The restrictions are generally based on statutory net income and/or certain levels of statutory surplus as determined in accordance with the relevant statutory accounting requirements of the individual domiciliary states or states in which any of the (re)insurance subsidiaries are commercially domiciled. Generally, prior regulatory approval must be obtained before an insurer may make a distribution above a specified level. The U.S. (re)insurance subsidiaries are also required to maintain minimum levels of solvency and liquidity as determined by law, and to comply with Risk-Based Capital ("RBC") requirements and licensing rules as specified by the National Association of Insurance Commissioners ("NAIC"). RBC is used to evaluate the adequacy of capital and surplus maintained by our U.S. (re)insurance subsidiaries in relation to three major risk areas associated with: (i) asset risk; (ii) insurance risk and (iii) other risks. For all of our U.S. (re)insurance subsidiaries, with the exception of one subsidiary which has a permitted accounting practice to treat an adverse development cover reinsurance agreement as prospective reinsurance, there are no prescribed or permitted statutory accounting practices that differ significantly from the statutory accounting principles established by NAIC. As of December 31, 2020, all of our U.S. non-life (re)insurance subsidiaries exceeded their required levels of risk-based capital. On an aggregate basis, our U.S. non-life (re)insurance subsidiaries exceeded their minimum levels of risk-based capital as of December 31, 2020 by $362.2 million (2019: $488.3 million). Europe Our Liechtenstein insurance subsidiary (StarStone Insurance SE) is regulated by the Liechtenstein Financial Market Authority ("FMA") pursuant to the Liechtenstein Insurance Supervisory Act. This subsidiary is obligated to maintain a minimum solvency margin based on the Solvency II regulations. As of December 31, 2020, this subsidiary exceeded the Solvency II requirements by $97.6 million (2019: $119.0 million). The amount of dividends that this subsidiary is permitted to distribute is restricted to freely distributable reserves, which consist of retained earnings, the current year profit and legal reserves. Any dividend exceeding the current year profit requires the FMA’s approval. Solvency and capital requirements for this subsidiary are based on the Solvency II framework and must continue to be met following any distribution. Australia The Company’s Australian insurance subsidiary is regulated and subject to prudential supervision by the Australian Prudential Regulation Authority (“APRA”). APRA is the primary regulatory body responsible for regulating compliance with the Insurance Act 1973. APRA’s prudential standards require that all insurers maintain and meet prescribed capital adequacy requirements designed to ensure that insurers to meet their insurance obligations under a wide range of scenarios.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	23. COMMITMENTS AND CONTINGENCIES Concentration of Credit Risk We believe that there are no significant concentrations of credit risk associated with our cash and cash equivalents, fixed maturity investments, or other investments. Our cash and investments are managed pursuant to guidelines that follow prudent standards of diversification and liquidity, and limit the allowable holdings of a single issue and issuers. We are also subject to custodial credit risk on our investments, which we manage by diversifying our holdings amongst large financial institutions that are highly regulated. We have exposure to credit risk on certain of our assets pledged to ceding companies under insurance contracts. In addition, we are potentially exposed should any insurance intermediaries be unable to fulfill their contractual obligations with respect to payments of balances owed to and by us. Credit risk exists in relation to (re)insurance balances recoverable on paid and unpaid losses. We remain liable to the extent that counterparties do not meet their contractual obligations and, therefore, we evaluate and monitor concentration of credit risk among our (re)insurers. We are also subject to credit risk in relation to funds held by reinsured companies. Under funds held arrangements, the reinsured company has retained funds that would otherwise have been remitted to our reinsurance subsidiaries. The funds may be placed into trust or subject to other security arrangements. However, we generally have the contractual ability to offset any shortfall in the payment of the funds held balances with amounts owed by us. As of December 31, 2020, we had a significant funds held concentration of $955.0 million to one reinsured company which has financial strength credit ratings of A+ from A.M. Best and AA from S&P. We limit the amount of credit exposure to any one counterparty and none of our counterparty credit exposures, excluding U.S. government instruments and the counterparty noted above, exceeded 10% of shareholders’ equity as of December 31, 2020. Our credit exposure to the U.S. government was $1.4 billion as of December 31, 2020. Legal Proceedings We are, from time to time, involved in various legal proceedings in the ordinary course of business, including litigation and arbitration regarding claims. Estimated losses relating to claims arising in the ordinary course of business, including the anticipated outcome of any pending arbitration or litigation are included in the liability for losses and LAE in our consolidated balance sheets. In addition to claims litigation, we may be subject to other lawsuits and regulatory actions in the normal course of business, which may involve, among other things, allegations of underwriting errors or omissions, employment claims or regulatory activity. We do not believe that the resolution of any currently pending legal proceedings, either individually or taken as a whole, will have a material effect on our business, results of operations or financial condition. We anticipate that, similar to the rest of the (re)insurance industry, we will continue to be subject to litigation and arbitration proceedings in the ordinary course of business, including litigation generally related to the scope of coverage with respect to asbestos and environmental and other claims. Unfunded Investment Commitments As of December 31, 2020, we had unfunded commitments of $975.5 million to other investments, $68.7 million to equity method investments and $5.0 million to fixed maturity investments. Guarantees As of December 31, 2020 and 2019, parental guarantees and capital instruments supporting subsidiaries' insurance obligations were $1.5 billion and $1.0 billion, respectively. We also guarantee the Junior Subordinated Notes and the FAL facility, which are described in Note 15 - "Debt Obligations and Credit Facilities." Redeemable Noncontrolling Interest We have the right to purchase the RNCI interests from the RNCI holders at certain times in the future (each such right, a "call right") and the RNCI holders have the right to sell their RNCI interests to us at certain times in the future (each such right, a "put right"). Pursuant to the Exchange Transaction described in Note 21 - "Related Party Transactions" we exchanged a portion of our indirect interest in Northshore, the holding company that owns Atrium and Arden, for all of the Trident V Funds' indirect interest in StarStone U.S. on January 1, 2021. Following the closing of the Exchange Transaction, we have maintained a call right over the portion of SSHL owned by the Trident V Funds and the Dowling Funds, and they will maintain put rights to transfer those interests to us. Leases We have recognized a right-of-use asset and an offsetting lease liability on our consolidated balance sheets, relating primarily to office space and facilities that we have leased to conduct our business operations. On an ongoing basis we determine whether an arrangement is a lease or contains a lease at inception and also complete an assessment to determine the classification of each lease as either a finance lease or an operating lease. Our leases are all currently classified as operating leases. Our leases have remaining lease terms of one year to 36 years, some of which include options to extend the lease term for up to five years and some of which include options to terminate the lease within one year. We consider these options in determining the lease term used to establish our right-of-use assets and lease liabilities. Renewal options that we believe we are likely to exercise are considered when determining lease terms. Our lease agreements do not contain any material residual value guarantees or material restrictive covenants. Since a majority of our leases do not provide an implicit discount rate, we use our collateralized incremental borrowing rate in determining the present value of lease payments. The table below provides the lease cost and other information relating to our operating leases for the years ended December 31, 2020 and 2019: 2020 2019 Lease cost: Operating lease cost $ 12,720 $ 13,627 Short-term lease cost (1) 246 — Total lease cost 12,966 13,627 Sub-lease income (2) (553) (542) Total net lease cost $ 12,413 $ 13,085 Other information: Operating cash paid for amounts included in the measurement of lease liabilities $ 13,421 $ 11,129 Non-cash activity: right-of-use assets relating to leases 295 57,536 Weighted-average remaining lease term 6.1 years 6.3 years Weighted-average discount rate 6.5 % 6.3 % (1) Leases with an initial lease term of twelve months or less are not recognized within our consolidated balance sheets. (2) Sub-lease income consists of rental income received from third parties to whom we have sub-leased some of our leased office spaces and is included within other income in our consolidated statements of earnings. Lease expense for the year ended December 31, 2018 was $11.3 million, relating to office space and facilities that we leased to conduct our business operations. The table below provides a summary of the operating leases recorded on our consolidated balance sheets for the years ended December 31, 2020 and 2019: Balance sheet classification 2020 2019 Right-of-use assets (1) (2) Other assets $ 32,297 $ 46,747 Current lease liabilities (2) Other liabilities 7,959 11,403 Non-current lease liabilities (2) Other liabilities 27,064 34,785 (1) Following our decision to put the StarStone International operations into orderly run-off effective June 10, 2020, we recorded total impairment charges of $3.5 million on the right-of-use assets relating to certain StarStone International operating leases as of December 31, 2020. (2) The right-of-use assets and the total lease liability balances exclude balances of $1.0 million and $0.8 million respectively, related to Atrium which have been reclassified to held-for-sale balances on our consolidated balance sheet as of December 31, 2020. The table below provides a summary of the contractual maturities of our operating lease liabilities: 2021 2022 2023 2024 2025 2026 and beyond Total lease payments Less: Imputed interest Present value of lease liabilities Contractual maturities $ 9,774 8,099 7,267 5,561 4,534 8,577 43,812 (8,789) $ 35,023

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Segment Information	24. SEGMENT INFORMATION We have three reportable segments of business that are each managed, operated and separately reported: (i) Non-life Run-off; (ii) Atrium; and (iii) StarStone. Our other activities, which do not qualify as a reportable segment, include our corporate expenses, debt servicing costs, holding company income and expenses, foreign exchange and other miscellaneous items. These segments are described in Note 1 - "Description of Business." As discussed in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations," the strategic transactions related to our Atrium and StarStone segments will enable us to focus on our core Non-life Run-off business. We will review and assess our segment structure in 2021 to reflect the changes to the StarStone and Atrium segments in the fourth quarter of 2020 and the first quarter of 2021, respectively. The following tables set forth selected and consolidated statement of earnings results by segment for the years ended December 31, 2020, 2019, and 2018: 2020 Non-life Atrium StarStone Other Total Gross premiums written $ 5,191 $ 206,656 $ 326,695 $ 13,441 $ 551,983 Net premiums written $ 2,987 $ 183,194 $ 233,202 $ 13,441 $ 432,824 Net premiums earned $ 58,695 $ 175,393 $ 318,115 $ 19,889 $ 572,092 Net incurred losses and LAE (44,995) (87,226) (266,738) (16,967) (415,926) Acquisition costs (20,177) (59,611) (90,797) (435) (171,020) Operating expenses (200,990) (13,078) (81,853) — (295,921) Underwriting income (loss) (207,467) 15,478 (121,273) 2,487 (310,775) Net investment income 282,048 5,542 27,443 (12,216) 302,817 Net realized and unrealized gains 1,627,526 4,165 10,328 — 1,642,019 Fees and commission income 19,462 22,984 — — 42,446 Other income (losses) 99,940 131 3,734 (2,673) 101,132 Corporate expenses (97,727) (21,522) (42,011) (44,298) (205,558) Interest income (expense) (67,195) — (2,110) 9,997 (59,308) Net foreign exchange gains (losses) (13,214) 4,327 (10,140) 2,634 (16,393) EARNINGS (LOSS) BEFORE INCOME TAXES 1,643,373 31,105 (134,029) (44,069) 1,496,380 Income tax expense (17,412) (4,122) (902) (1,391) (23,827) Earnings from equity method investments 238,569 — — — 238,569 NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS 1,864,530 26,983 (134,931) (45,460) 1,711,122 Net earnings from discontinued operations, net of income taxes — — 16,251 — 16,251 NET EARNINGS (LOSS) 1,864,530 26,983 (118,680) (45,460) 1,727,373 Net (earnings) loss attributable to noncontrolling interest 1,597 (11,059) 37,133 — 27,671 NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR 1,866,127 15,924 (81,547) (45,460) 1,755,044 Dividends on preferred shares — — — (35,700) (35,700) NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS $ 1,866,127 $ 15,924 $ (81,547) $ (81,160) $ 1,719,344 Underwriting ratios: Loss ratio 49.7 % 83.8 % Acquisition expense ratio 34.0 % 28.5 % Operating expense ratio 7.5 % 25.8 % Combined ratio 91.2 % 138.1 % 2019 Non-life Atrium StarStone Other Total Gross premiums written $ (25,069) $ 192,373 $ 472,815 $ 18,534 $ 658,653 Net premiums written $ (25,338) $ 172,356 $ 379,523 $ 18,512 $ 545,053 Net premiums earned $ 168,496 $ 164,059 $ 451,112 $ 20,380 $ 804,047 Net incurred losses and LAE (51,625) (77,276) (469,240) (16,038) (614,179) Acquisition costs (73,642) (56,956) (109,369) (642) (240,609) Operating expenses (199,756) (14,452) (60,627) — (274,835) Underwriting income (loss) (156,527) 15,375 (188,124) 3,700 (325,576) Net investment income 275,236 7,049 34,396 (8,410) 308,271 Net realized and unrealized gains 968,350 6,195 31,572 5,849 1,011,966 Fees and commission income 18,293 10,160 — — 28,453 Other income 34,809 140 329 1,792 37,070 Corporate expenses (70,689) (13,825) (7,790) (45,945) (138,249) Interest income (expense) (62,055) — (475) 9,989 (52,541) Net foreign exchange gains (losses) 9,918 (504) (1,505) 3 7,912 EARNINGS (LOSS) BEFORE INCOME TAXES 1,017,335 24,590 (131,597) (33,022) 877,306 Income tax expense (7,250) (4,033) (1,004) (85) (12,372) Earnings (losses) from equity method investments 56,128 — (218) — 55,910 NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS 1,066,213 20,557 (132,819) (33,107) 920,844 Net earnings from discontinued operations, net of income taxes — — 7,375 — 7,375 NET EARNINGS (LOSS) 1,066,213 20,557 (125,444) (33,107) 928,219 Net (earnings) loss attributable to noncontrolling interest (6,409) (8,432) 24,711 — 9,870 NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR 1,059,804 12,125 (100,733) (33,107) 938,089 Dividends on preferred shares — — — (35,914) (35,914) NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS $ 1,059,804 $ 12,125 $ (100,733) $ (69,021) $ 902,175 Underwriting ratios: Loss ratio 47.1 % 104.0 % Acquisition expense ratio 34.7 % 24.2 % Operating expense ratio 8.8 % 13.5 % Combined ratio 90.6 % 141.7 % 2018 Non-life Atrium StarStone Other Total Gross premiums written $ (8,910) $ 171,494 $ 622,570 $ 32,378 $ 817,532 Net premiums written $ (9,217) $ 153,488 $ 478,009 $ 32,067 $ 654,347 Net premiums earned $ 9,427 $ 146,315 $ 515,163 $ 24,874 $ 695,779 Net incurred losses and LAE 306,067 (69,810) (543,080) (16,899) (323,722) Acquisition costs (4,006) (50,646) (120,517) (2,686) (177,855) Operating expenses (158,731) (17,777) (98,137) — (274,645) Underwriting income (loss) 152,757 8,082 (246,571) 5,289 (80,443) Net investment income 226,287 5,686 27,000 2,725 261,698 Net realized and unrealized losses (381,712) (3,251) (12,320) (10,249) (407,532) Fees and commission income 16,466 18,622 — — 35,088 Other income (losses) 35,978 162 (550) (1,517) 34,073 Corporate expenses (39,093) (6,921) — (28,127) (74,141) Interest income (expense) (30,616) — (103) 5,023 (25,696) Net foreign exchange gains (losses) 2,534 (3,394) (2,832) 1,048 (2,644) EARNINGS (LOSS) BEFORE INCOME TAXES (17,399) 18,986 (235,376) (25,808) (259,597) Income tax benefit (expense) 3,581 (3,732) 3,892 (52) 3,689 Earnings from equity method investments 42,147 — — — 42,147 NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS 28,329 15,254 (231,484) (25,860) (213,761) Net earnings from discontinued operations, net of income taxes — — 1,489 — 1,489 NET EARNINGS (LOSS) 28,329 15,254 (229,995) (25,860) (212,272) Net (earnings) loss attributable to noncontrolling interest (3,107) (6,257) 71,415 — 62,051 NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR 25,222 8,997 (158,580) (25,860) (150,221) Dividend on preferred shares — — — (12,133) (12,133) NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS $ 25,222 $ 8,997 $ (158,580) $ (37,993) $ (162,354) Underwriting ratios: Loss ratio 47.7 % 105.4 % Acquisition expense ratio 34.6 % 23.4 % Operating expense ratio 12.2 % 19.1 % Combined ratio 94.5 % 147.9 % Gross Premiums Written by Geographical Area The following table summarizes our gross premiums written for the year ended December 31, 2020 by geographic area. Geographic distribution in future years is subject to variation based upon market conditions and business strategies. Non-life Run-off Atrium StarStone Other Total Total % Total % Total % Total % Total % (In thousands of U.S. dollars, except percentages) United States $ 4,969 95.7 $ 103,411 50.1 $ 61,104 18.7 $ 13,441 100.0 $ 182,925 33.2 United Kingdom (229) (4.4) 14,054 6.8 105,057 32.2 — — 118,882 21.5 Europe 1,615 31.1 19,705 9.5 62,181 19.0 — — 83,501 15.1 Asia — — 7,834 3.8 60,262 18.4 — — 68,096 12.3 Rest of World (1,164) (22.4) 61,652 29.8 38,091 11.7 — — 98,579 17.9 Total $ 5,191 100.0 $ 206,656 100.0 $ 326,695 100.0 $ 13,441 100.0 $ 551,983 100.0 Assets by Segment Invested assets are managed on a subsidiary by subsidiary basis, and investment income and realized and unrealized gains (losses) on investments are recognized in each segment as earned. Our total assets as of December 31, 2020 and 2019 by segment and for our other activities were as follows: 2020 2019 Assets by Segment: Non-life Run-off (1) $ 19,062,400 $ 15,775,409 Atrium (2) 615,778 580,405 StarStone 2,583,247 3,985,137 Other (614,141) (514,852) Total assets $ 21,647,284 $ 19,826,099 (1) The total assets within the Non-life Run-off segment include assets of $95.5 million related to Arden's operations that have been included within Northshore's held-for-sale assets in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations" and Discontinued Operations." (2) The total assets within the Atrium segment are all included within Northshore's held-for-sale assets in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations".

Unaudited Condensed Quarterly F

Unaudited Condensed Quarterly Financial Data	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Unaudited Condensed Quarterly Financial Data	25. UNAUDITED CONDENSED QUARTERLY FINANCIAL DATA December 31, September 30, June 30, March 31, 2020 2019 2020 2019 2020 2019 2020 2019 INCOME Net premiums earned $ 108,146 $ 185,336 $ 161,724 $ 175,802 $ 142,871 $ 190,962 $ 159,351 $ 251,947 Fees and commission income 14,121 9,522 10,787 6,437 10,010 6,017 7,528 6,477 Net investment income 61,530 76,847 72,130 81,502 94,443 74,271 74,714 75,651 Net realized and unrealized gains (losses) 803,467 153,477 500,005 145,060 967,608 260,669 (629,061) 452,760 Other income (losses) 33,372 21,703 48,404 822 (1,087) 8,831 20,443 5,714 1,020,636 446,885 793,050 409,623 1,213,845 540,750 (367,025) 792,549 EXPENSES Net incurred losses and loss adjustment expenses 76,248 48,068 109,686 163,258 186,692 146,554 43,300 256,299 Acquisition costs 38,202 78,417 37,708 33,310 49,067 51,081 46,043 77,801 General and administrative expenses 142,394 116,780 115,828 97,365 144,830 100,676 98,427 98,263 Interest expense 16,872 13,519 15,003 14,950 14,018 13,036 13,415 11,036 Net foreign exchange losses (gains) 15,018 12,186 8,156 (13,665) 5,158 (2,579) (11,939) (3,854) 288,734 268,970 286,381 295,218 399,765 308,768 189,246 439,545 EARNINGS (LOSS) BEFORE INCOME TAXES 731,902 177,915 506,669 114,405 814,080 231,982 (556,271) 353,004 Income tax benefit (expense) 1,468 12,893 (13,915) (13,465) (16,652) (7,698) 5,272 (4,102) Earnings (losses) from equity method investments 85,844 11,722 149,065 17,703 (8,790) 17,713 12,450 8,772 NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS 819,214 202,530 641,819 118,643 788,638 241,997 (538,549) 357,674 Net earnings (loss) from discontinued operations, net of income taxes 15,441 (4,666) 4,031 7,916 (1,152) (3,943) (2,069) 8,068 NET EARNINGS (LOSS) 834,655 197,864 645,850 126,559 787,486 238,054 (540,618) 365,742 Net (earnings) loss attributable to noncontrolling interest (3,131) 4,900 (21,912) 109 19,992 2,713 32,722 2,148 NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR 831,524 202,764 623,938 126,668 807,478 240,767 (507,896) 367,890 Dividends on preferred shares (8,925) (8,925) (8,925) (8,925) (8,925) (8,925) (8,925) (9,139) NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS $ 822,599 $ 193,839 $ 615,013 $ 117,743 $ 798,553 $ 231,842 $ (516,821) $ 358,751 Earnings (loss) per ordinary share attributable to Enstar ordinary shareholders: Basic: Net earnings (loss) from continuing operations $ 37.91 $ 9.15 $ 28.39 $ 5.26 $ 37.06 $ 10.90 $ (23.93) $ 16.49 Net earnings (loss) from discontinued operations 0.33 (0.13) 0.11 0.22 (0.03) (0.11) (0.05) 0.22 Basic $ 38.24 $ 9.02 $ 28.50 $ 5.48 $ 37.03 $ 10.79 $ (23.98) $ 16.71 Diluted (1) : Net earnings (loss) from continuing operations $ 37.47 $ 9.02 $ 28.13 $ 5.21 $ 36.68 $ 10.81 $ (23.93) $ 16.35 Net earnings (loss) from discontinued operations 0.32 (0.13) 0.11 0.21 (0.03) (0.11) (0.05) 0.22 Net earnings (loss) per ordinary share $ 37.79 $ 8.89 $ 28.24 $ 5.42 $ 36.65 $ 10.70 $ (23.98) $ 16.57 (1) During a period of loss, the basic weighted average ordinary shares outstanding is used in the denominator of the diluted loss per ordinary share computation as the effect of including potentially dilutive securities would be anti-dilutive.

Schedule I - Summary of Investm

Schedule I - Summary of Investments Other Than Investments in Related Parties	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Abstract]
Schedule I - Summary of Investments Other Than Investments in Related Parties	SCHEDULE I ENSTAR GROUP LIMITED SUMMARY OF INVESTMENTS OTHER THAN INVESTMENTS IN RELATED PARTIES As of December 31, 2020 (Expressed in thousands of U.S. Dollars) Type of investment Cost (1) Fair Value Amount at which shown in the balance sheet Short-term and fixed maturity investments — Trading and short-term and fixed maturity investments within funds held - directly managed: (2) U.S. government and agency $ 219,487 $ 233,050 $ 233,050 U.K. government 34,494 37,508 37,508 Other government 321,306 352,026 352,026 Corporate 3,353,054 3,749,383 3,749,383 Municipal 116,588 132,637 132,637 Residential mortgage-backed 219,360 225,074 225,074 Commercial mortgage-backed 554,639 577,602 577,602 Asset-backed 349,941 339,675 339,675 Total 5,168,869 5,646,955 5,646,955 Short-term and fixed maturity investments — AFS: (2) U.S. government and agency 715,527 717,998 717,998 U.K. government 12,494 13,574 13,574 Other government 142,459 150,127 150,127 Corporate 1,873,184 1,937,349 1,937,349 Municipal 28,881 30,032 30,032 Residential mortgage-backed 326,268 328,871 328,871 Commercial mortgage-backed 273,516 276,488 276,488 Asset-backed 199,467 199,610 199,610 Total 3,571,796 3,654,049 3,654,049 Equities (3) 444,570 512,557 512,557 Other investments, at fair value (4) 982,770 982,770 982,770 Total $ 10,168,005 $ 10,796,331 $ 10,796,331 (1) Original cost of fixed maturity securities is reduced by repayments and adjusted for amortization of premiums or accretion of discounts. (2) The difference in the amount of fixed maturities shown at fair value and the fixed maturities shown in our consolidated balance sheet relates to the fair value of $18.2 million as of December 31, 2020 for our investment in fixed maturities issued by affiliates of Stone Point. Refer to Note 21 - "Related Party Transactions" of the notes to the consolidated financial statements. (3) The difference in the amount of equities shown at fair value and the equities shown in our consolidated balance sheet relates to the fair value of $77.1 million as of December 31, 2020 for our investment in a registered investment company affiliated with entities owned by Trident, $26.9 million as a co-investor alongside Stone Point and a $230.3 million investment in AmTrust. Refer to Note 21 - "Related Party Transactions" of the notes to the consolidated financial statements. (4) The difference in the amount of other investments shown at fair value and the other investments shown in our consolidated balance sheet relates to the fair value of $3.3 billion as of December 31, 2020 for our other investments in funds or companies owned by or affiliated with certain related parties. Refer to Note 21 - "Related Party Transactions" of the notes to the consolidated financial statements.

Schedule II - Condensed Financi

Schedule II - Condensed Financial Statements	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Disclosure [Abstract]
Schedule II - Condensed Financial Statements	SCHEDULE II ENSTAR GROUP LIMITED CONDENSED FINANCIAL INFORMATION OF REGISTRANT Balance Sheets - Parent Company Only 2020 2019 (in thousands of U.S. ASSETS Cash and cash equivalents $ 7,872 $ 4,568 Balances due from subsidiaries 18,951 134,897 Investments in subsidiaries 7,887,255 6,050,197 Other assets 8,047 6,391 TOTAL ASSETS $ 7,922,125 $ 6,196,053 LIABILITIES Debt obligations $ 903,447 $ 1,191,207 Balances due to subsidiaries 300,987 135,532 Other liabilities 43,296 27,131 TOTAL LIABILITIES 1,247,730 1,353,870 COMMITMENTS AND CONTINGENCIES SHAREHOLDERS’ EQUITY Ordinary shares (par value $1 each, issued and outstanding 2020: 22,085,232; 2019: 21,511,505): Voting Ordinary Shares (issued and outstanding 2020: 18,575,550; 2019: 18,001,823) 18,576 18,002 Non-voting convertible ordinary Series C Shares (issued and outstanding 2020 and 2019: 2,599,672) 2,600 2,600 Non-voting convertible ordinary Series E Shares (issued and outstanding 2020 and 2019: 910,010) 910 910 Preferred Shares: Series C Preferred Shares (issued and held in treasury 2020 and 2019: 388,571) 389 389 Series D Preferred Shares (issued and outstanding 2020 and 2019: 16,000) 400,000 400,000 Series E Preferred Shares (issued and outstanding 2020 and 2019: 4,400) 110,000 110,000 Treasury shares, at cost (Series C Preferred Shares 2020 and 2019: 388,571) (421,559) (421,559) Joint Share Ownership Plan (voting ordinary shares, held in trust 2020: 565,630; 2019: 0) (566) — Additional paid-in capital 1,836,074 1,836,778 Accumulated other comprehensive income 80,659 7,171 Retained earnings 4,647,312 2,887,892 Total Enstar Group Limited Shareholders’ Equity 6,674,395 4,842,183 TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY $ 7,922,125 $ 6,196,053 See accompanying notes to the Condensed Financial Information of Registrant SCHEDULE II ENSTAR GROUP LIMITED CONDENSED FINANCIAL INFORMATION OF REGISTRANT - CONTINUED Statements of Earnings - Parent Company Only For the Years Ended December 31, 2020, 2019 and 2018 2020 2019 2018 (in thousands of U.S. dollars) INCOME Net investment income $ 1,680 $ 3,649 $ 142 1,680 3,649 142 EXPENSES General and administrative expenses 45,689 44,964 68,977 Interest expense 51,739 51,508 27,353 Net foreign exchange losses (gains) (2,655) (21,516) 7,655 94,773 74,956 103,985 EARNINGS (LOSSES) BEFORE EQUITY IN UNDISTRIBUTED EARNINGS OF SUBSIDIARIES (93,093) (71,307) (103,843) Equity in undistributed earnings (losses) of subsidiaries - continuing operations 1,831,886 1,002,021 (47,867) Equity in undistributed earnings (losses) of subsidiaries - discontinued operations 16,251 7,375 1,489 NET EARNINGS 1,755,044 938,089 (150,221) Dividends on preferred shares (35,700) (35,914) (12,133) NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS $ 1,719,344 $ 902,175 $ (162,354) See accompanying notes to the Condensed Financial Information of Registrant Statements of Comprehensive Income - Parent Company Only For the Years Ended December 31, 2020, 2019 and 2018 2020 2019 2018 (in thousands of U.S. dollars) NET EARNINGS $ 1,755,044 $ 938,089 $ (150,221) OTHER COMPREHENSIVE INCOME (LOSS) RELATING TO SUBSIDIARIES, NET OF TAX 73,488 (3,269) (27) COMPREHENSIVE INCOME $ 1,828,532 $ 934,820 $ (150,248) See accompanying notes to the Condensed Financial Information of Registrant SCHEDULE II ENSTAR GROUP LIMITED CONDENSED FINANCIAL INFORMATION OF REGISTRANT - CONTINUED Statements of Cash Flows - Parent Company Only For the Years Ended December 31, 2020, 2019 and 2018 2020 2019 2018 (in thousands of U.S. dollars) OPERATING ACTIVITIES: Net cash flows provided by (used in) operating activities $ 117,220 $ (128,462) $ (128,382) INVESTING ACTIVITIES: Dividends and return of capital from subsidiaries 44,000 65,500 101,000 Contributions to subsidiaries (26,000) (240,382) (660,339) Net cash flows provided by (used in) investing activities 18,000 (174,882) (559,339) FINANCING ACTIVITIES: Net proceeds from the issuance of preferred shares — — 495,357 Dividends on preferred shares (35,700) (35,914) (12,133) Repurchase of shares (26,006) — — Repayment of loans (449,210) (219,000) (898,633) Receipt of loans 379,000 547,613 1,115,885 Net cash flows provided by (used in) financing activities (131,916) 292,699 700,476 NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS 3,304 (10,645) 12,755 CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR 4,568 15,213 2,458 CASH AND CASH EQUIVALENTS, END OF YEAR $ 7,872 $ 4,568 $ 15,213 See accompanying notes to the Condensed Financial Information of Registrant Notes to the Condensed Financial Information of Registrant The Condensed Financial Information of Registrant should be read in conjunction with our consolidated financial statements and the accompanying notes thereto included in Part II - Item 8 of this Annual Report on Form 10-K. Our wholly-owned and majority owned subsidiaries are recorded based upon our proportionate share of our subsidiaries' net assets (similar to presenting them on the equity method). Net investment income relates to interest on loans to subsidiaries. For the years ended December 31, 2020, 2019, and 2018, interest paid was $46.5 million, $46.5 million, and $25.1 million, respectively. Investing activities in the Condensed Statements of Cash Flows primarily represents the flow of funds to and from subsidiaries to provide cash on hand to fund business acquisitions and significant new business. Non-Cash investing activities during the years ended December 31, 2020, 2019, and 2018, included: i. $130.0 million, $0 and $0, respectively, for dividends and return of capital from subsidiaries. In 2020, these transactions were to settle intercompany balances, resulting in a net reduction in balances due to subsidiaries and a decrease in investments in subsidiaries. ii. $0, $0 and $414.8 million, respectively, for contributions to subsidiaries. In 2018, these transactions represented the contribution of the acquired outstanding shares and warrants of KaylaRe Holdings, Ltd, to another subsidiary company. As of December 31, 2020 and 2019, parental guarantees and capital support instruments supporting subsidiaries' insurance obligations were $1.5 billion and $1.0 billion, respectively. In addition, as of December 31, 2020 and 2019, there were $210.0 million and $252.0 million, respectively, of unsecured letters of credit for Funds at Lloyd's which have a parental guarantee. Furthermore, as of December 31, 2020, we also guarantee the Junior Subordinated Notes issued in 2020 for an aggregate principal amount of $350.0 million. As of December 31, 2020 and 2019, retained earnings were $4,647.3 million and $2,887.9 million, respectively, an increase of $1,759.4 million. This increase was primarily attributable to the net earnings of $1,719.3 million.

Schedule III - Supplementary In

Schedule III - Supplementary Insurance Information	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Abstract]
Schedule III - Supplementary Insurance Information	SCHEDULE III ENSTAR GROUP LIMITED SUPPLEMENTARY INSURANCE INFORMATION (Expressed in thousands of U.S. Dollars) As of December 31, Year ended December 31, Deferred Reserves Unearned Policy Benefits for Life and Annuity Contracts Net Net Losses Amortization Other Operating Expenses Net 2020 Non-life Run-off (1) $ 22,736 $ 9,235,082 $ 71,629 $ — $ 58,695 $ 282,048 $ 44,995 $ 20,177 $ 298,717 $ 2,987 Atrium (1) — — — — 175,393 5,542 87,226 59,611 34,600 183,194 StarStone 21,439 1,327,956 191,502 — 318,115 27,443 266,738 90,797 123,864 233,202 Other 264 30,244 11,550 — 19,889 (12,216) 16,967 435 44,298 13,441 Total $ 44,439 $ 10,593,282 $ 274,681 $ — $ 572,092 $ 302,817 $ 415,926 $ 171,020 $ 501,479 $ 432,824 2019 Non-life Run-off $ 41,753 $ 8,295,361 $ 129,715 $ — $ 168,496 $ 275,236 $ 51,625 $ 73,642 $ 270,445 $ (25,338) Atrium 22,184 231,672 80,863 — 164,059 7,049 77,276 56,956 28,277 172,356 StarStone 52,188 1,318,294 305,116 — 451,112 34,396 469,240 109,369 68,417 379,523 Other 388 23,077 17,998 — 20,380 (8,410) 16,038 642 45,945 18,512 Total $ 116,513 $ 9,868,404 $ 533,692 $ — $ 804,047 $ 308,271 $ 614,179 $ 240,609 $ 413,084 $ 545,053 2018 Non-life Run-off $ 4,378 $ 7,540,662 $ 136,023 $ — $ 9,427 $ 226,287 $ (306,067) $ 4,006 $ 197,824 $ (9,217) Atrium 20,355 241,284 70,429 — 146,315 5,686 69,810 50,646 24,698 153,488 StarStone 62,161 1,247,989 382,605 — 515,163 27,000 543,080 120,517 98,137 478,009 Other 364 18,861 17,002 105,080 24,874 2,725 16,899 2,686 28,127 32,067 Total $ 87,258 $ 9,048,796 $ 606,059 $ 105,080 $ 695,779 $ 261,698 $ 323,722 $ 177,855 $ 348,786 $ 654,347 (1) As of December 31, 2020, the assets and liabilities of Northshore, the holding company which owns Atrium and Arden (a Non-life Run-off subsidiary), were classified as held-for-sale. Deferred acquisition costs, reserves for losses and loss adjustment expenses and unearned premiums for Northshore were $24.0 million, $254.1 million and

Schedule IV - Reinsurance

Schedule IV - Reinsurance	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract]
Schedule IV - Reinsurance	SCHEDULE IV ENSTAR GROUP LIMITED REINSURANCE For the Years Ended December 31, 2020, 2019 and 2018 (Expressed in thousands of U.S. Dollars) Gross Ceded to Assumed Net Amount Percentage 2020 Premiums earned: Property and casualty $ 542,119 $ (157,826) $ 187,799 $ 572,092 32.8 % Total premiums earned $ 542,119 $ (157,826) $ 187,799 $ 572,092 2019 Life insurance in force $ 725,293 $ (65,795) $ — $ 659,498 — % Premiums earned: Property and casualty 679,212 (145,460) 269,023 802,775 33.5 % Life and annuities 1,295 (23) — 1,272 — % Total premiums earned $ 680,507 $ (145,483) $ 269,023 $ 804,047 2018 Life insurance in force $ 855,366 $ (84,603) $ — $ 770,763 — % Premiums earned: Property and casualty 539,169 (166,308) 319,052 691,913 46.1 % Life and annuities 3,892 (26) — 3,866 — % Total premiums earned $ 543,061 $ (166,334) $ 319,052 $ 695,779

Schedule V - Valuation and Qual

Schedule V - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule V - Valuation and Qualifying Accounts	SCHEDULE V ENSTAR GROUP LIMITED VALUATION AND QUALIFYING ACCOUNTS For the Years Ended December 31, 2020, 2019 and 2018 (Expressed in thousands of U.S. Dollars) Balance at Beginning of Year Charged to costs and expenses Charged to other accounts (1) Deductions (2) Balance at End of Year December 31, 2020 Reinsurance balances recoverable on paid and unpaid losses: Allowance for estimated uncollectible reinsurance $ 147,639 $ — $ 124 $ (10,641) $ 137,122 Insurance balances recoverable: Allowance for estimated uncollectible insurance 3,818 — 1,006 — 4,824 Valuation allowance for deferred tax assets 117,390 3,854 — (3,015) 118,229 December 31, 2019 Reinsurance balances recoverable on paid and unpaid losses: Allowance for estimated uncollectible reinsurance 156,732 — 111 (9,204) 147,639 Insurance balances recoverable: Allowance for estimated uncollectible insurance — — 3,818 — 3,818 Valuation allowance for deferred tax assets 212,113 2,792 — (97,515) 117,390 December 31, 2018 Reinsurance balances recoverable on paid and unpaid losses: Allowance for estimated uncollectible reinsurance 165,213 — (1,837) (6,644) 156,732 Valuation allowance for deferred tax assets 188,300 (2,492) 18,000 8,305 212,113 (1) The 2020 amount includes $3.0 million for the cumulative effect of change in accounting principle. (2) Credited to the related asset account.

Schedule VI - Supplementary Inf

Schedule VI - Supplementary Information Concerning Property/Casualty Insurance Operations	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Abstract]
Schedule VI - Supplementary Information Concerning Property/Casualty Insurance Operations	SCHEDULE VI ENSTAR GROUP LIMITED SUPPLEMENTARY INFORMATION CONCERNING PROPERTY/CASUALTY INSURANCE OPERATIONS As of and for the years ended December 31, 2020, 2019 and 2018 (Expressed in thousands of U.S. Dollars) As of December 31, Year ended December 31, Affiliation with Registrant Deferred Acquisition Costs Reserves for Unpaid Losses and Loss Adjustment Expenses Unearned Net Premiums Earned Net Investment Income Net Losses and Loss Expenses Incurred Net Paid Losses and Loss Expenses Amortization of Deferred Acquisition Costs Net Premiums Written Current Year Prior Year Consolidated Subsidiaries 2020 $ 44,439 $ 10,593,282 $ 274,681 $ 572,092 $ 302,817 $ 405,178 $ 10,748 $ (1,485,489) $ 171,020 $ 432,824 2019 116,513 9,868,404 533,692 802,775 307,775 580,074 34,105 (1,788,470) 240,432 543,781 2018 87,258 9,048,796 606,059 691,912 260,120 533,081 (209,359) (1,334,786) 177,855 650,484

Significant Accounting Polici_2

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

Business Acquisitions (Tables)

Business Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2020
Morse TEC
Business Acquisition [Line Items]
Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed as of Date of Acquisition	The following table summarizes the fair values of the assets acquired and liabilities assumed in the Morse TEC transaction at the acquisition date, which were allocated to the Non-life Run-off segment. ASSETS Cash and cash equivalents $ 171,412 Deferred tax assets 140,000 Other assets - insurance balances receivable 371,116 TOTAL ASSETS 682,528 LIABILITIES Defendant asbestos and environmental liabilities 662,507 Other liabilities 20,021 TOTAL LIABILITIES $ 682,528 NET ASSETS ACQUIRED AT FAIR VALUE —
Pro Forma Condensed Combined Statement of Earnings	The table below summarizes the results of the Morse TEC operations, which were included in our consolidated statement of earnings from the acquisition date to December 31, 2019: Net investment income $ 488 General and administrative expenses (1,459) Other expenses (1,512) Net loss $ (2,483)
Maiden Re
Business Acquisition [Line Items]
Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed as of Date of Acquisition	The following table summarizes the fair values of the assets acquired and liabilities assumed (excluding preexisting relationships and net of the intercompany cession assumed as part of the transaction) in the Maiden Re North America transaction at the acquisition date, which have all been allocated to the Non-life Run-off segment. ASSETS Fixed maturities, trading, at fair value $ 1,098,593 Short-term investments, trading, at fair value 3,508 Total investments 1,102,101 Cash and cash equivalents 12,035 Restricted cash and cash equivalents 26,871 Premiums receivable 138,378 Prepaid reinsurance premiums 3,257 Reinsurance balances recoverable 87,018 Other assets 96,669 TOTAL ASSETS $ 1,466,329 LIABILITIES Losses and LAE $ 1,027,367 Unearned premiums 85,696 Other liabilities 56,618 TOTAL LIABILITIES 1,169,681 NET ASSETS ACQUIRED AT FAIR VALUE $ 296,648
Pro Forma Condensed Combined Statement of Earnings	The table below summarizes the results of the Maiden Re North America operations, which were included in our consolidated statement of earnings from the acquisition date to December 31, 2018: Net investment income $ 675 Net unrealized gains 3,749 General and administrative expenses (435) Net earnings $ 3,989
Purchase Price and Fair Value of Assets Acquired	The components of the consideration paid to acquire all of the outstanding shares of Maiden Re North America were as follows: Cash paid $ 286,375 Adjustment for the fair value of preexisting relationships 10,273 Total purchase price $ 296,648 Net assets acquired at fair value (including preexisting relationships) $ 296,648 Excess of purchase price over fair value of net assets acquired $ —
KaylaRe
Business Acquisition [Line Items]
Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed as of Date of Acquisition	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 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
Pro Forma Condensed Combined Statement of Earnings	The table below summarizes the results of the KaylaRe operations, which are included in our consolidated statement of earnings from the acquisition date to December 31, 2018: Premiums earned $ 13,627 Incurred losses and LAE (12,364) Acquisition costs (341) Underwriting income 922 Net investment income 3,096 Net unrealized gains (47,769) General and administrative expenses (2,164) Net loss $ (45,915)
Purchase Price and Fair Value of Assets Acquired	The components of the consideration paid to acquire all of the outstanding shares and warrants of KaylaRe were as follows: Fair value of Enstar ordinary shares issued $ 414,750 Fair value of previously held equity method investment 336,137 Adjustment for the fair value of preexisting relationships 37,169 Total purchase price $ 788,056 Net assets acquired at fair value (excluding preexisting relationships) $ 746,320 Excess of purchase price over fair value of net assets acquired $ 41,736 Number of Enstar ordinary shares issued 2,007,017 Closing price of Enstar voting ordinary shares as of May 14, 2018 $ 206.65 Fair value of Enstar ordinary shares issued to shareholders of KaylaRe $ 414,750 Carrying value of previously held equity method investment prior to the close of the transaction $ 320,130 Price-to-book multiple 1.05 Fair value of previously held equity method investment prior to the close of the transaction $ 336,137 Gain recognized on remeasurement of previously held equity method investment to fair value $ 16,007

Significant New Business (Table

Significant New Business (Tables)	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Summary Of Significant New Business	The table below sets forth a summary of significant new business that we have completed between January 1, 2018 and December 31, 2020: Transaction Date Completed Total Assets Assumed Deferred Charge Asset (1) Total Liabilities Assumed Net Fair Value Adjustment (2) Primary Nature of Business Hannover Re August 6, 2020 $ 182,498 N/A $ 209,713 $ (27,215) U.S. asbestos, environmental and workers' compensation liabilities Munich Re July 1, 2020 $ 100,956 N/A $ 100,956 N/A Australian public liability, professional liability and builders' warranty liabilities AXA Group (3) June 1, 2020 $ 179,681 N/A $ 179,681 N/A U.S. construction general liability Aspen June 1, 2020 $ 770,000 $ 11,746 $ 781,746 N/A Diversified mix of property, liability and specialty lines of business across the U.S., U.K. and Europe Lyft March 31, 2020 $ 465,000 N/A $ 465,000 N/A U.S. motor Zurich (3) October 1, 2019 $ 507,061 $ 115,815 $ 622,876 N/A U.S. asbestos and environmental liability Maiden Re Bermuda August 5, 2019 $ 445,000 $ 85,183 $ 530,183 N/A U.S. workers' compensation and General Casualty Amerisure April 11, 2019 $ 45,463 $ 2,873 $ 48,336 N/A U.S. construction defect AmTrust February 14, 2019 $ 1,143,949 $ 20,633 $ 1,164,582 N/A Lloyd's property, professional, marine, non-marine, affinity annual, extended warranty and political Allianz SE December 31, 2018 $ 70,000 N/A $ 70,000 N/A Asbestos and environmental Maiden Re Bermuda December 27, 2018 $ 70,425 $ 1,704 $ 72,129 N/A U.S. workers' compensation and motor Coca-Cola August 1, 2018 $ 103,617 $ 17,208 $ 120,825 N/A U.S. workers' compensation, auto liability, general and product liability Zurich Australia February 23, 2018 $ 268,657 N/A $ 280,764 $ (12,107) Australian motor Neon February 16, 2018 $ 525,673 N/A $ 546,298 $ (20,625) Medical malpractice, general liability, professional indemnity and marine Novae January 29, 2018 $ 1,095,730 N/A $ 1,163,198 $ (67,468) Financial, casualty, marine and energy, professional indemnity, aviation, motor and property The table below sets forth a summary of significant new business that we have signed or completed between January 1, 2021 and March 1, 2021: Transaction Date Completed Initial Estimate of Liabilities Assumed Primary Nature of Business AXA Group (4) N/A - Announced February 25, 2021 $ 1,395,000 Diversified mix of global casualty and professional lines ProSight (4) N/A - Announced January 15, 2021 $ 500,000 U.S. discontinued workers' compensation and excess workers' compensation lines of business and adverse development cover on a diversified mix of general liability classes of business CNA (4) February 5, 2021 $ 690,000 U.S. excess workers' compensation Liberty Mutual (4) January 8, 2021 $ 420,000 U.S. energy liability, construction liability and homebuilders liability (1) Where the estimated ultimate losses payable exceed the premium consideration received at the inception of the agreement, a deferred charge asset is recorded. (2) When the fair value option is elected for any retroactive reinsurance agreement, an initial net fair value adjustment is recorded at the inception of the agreement. (3) Effective October 1, 2020 and 2019, we ceded 10% of the AXA Group and Zurich transactions, respectively, to Enhanzed Reinsurance Ltd. ("Enhanzed Re"), in which we have an investment, on the same terms and conditions as those received by us. (4) The retroactive reinsurance agreements with AXA Group, ProSight, CNA and Liberty Mutual either closed or are expected to close in 2021 and therefore the related balances are not included in our consolidated financial statements as of December 31, 2020.

Divestitures, Held-For-Sale B_2

Divestitures, Held-For-Sale Businesses and Discontinued Operations (Tables)	12 Months Ended
	Dec. 31, 2020
Discontinued Operations and Disposal Groups [Abstract]
Financial Information of Held-For-Sale Business	The following table summarizes the components of Northshore's assets and liabilities held-for-sale on our consolidated balance sheet as of December 31, 2020: December 31, 2020 ASSETS Short-term investments, AFS, at fair value $ 1,720 Fixed maturities, trading, at fair value 154,026 Fixed maturities, AFS, at fair value 7,483 Other investments, at fair value 9,897 Total investments 173,126 Cash and cash equivalents 71,156 Restricted cash and cash equivalents 152,044 Premiums receivable 62,392 Reinsurance balances recoverable on paid and unpaid losses 37,341 Funds held by reinsured companies 32,226 Other assets 182,993 TOTAL ASSETS HELD-FOR-SALE $ 711,278 LIABILITIES Losses and loss adjustment expenses $ 254,149 Insurance and reinsurance balances payable 12,393 Debt obligations 39,850 Other liabilities 177,265 TOTAL LIABILITIES HELD-FOR-SALE $ 483,657 NET ASSETS HELD-FOR-SALE $ 227,621 StarStone U.S. comprised a substantial portion of the StarStone segment. We classified the assets and liabilities of StarStone U.S. as held-for-sale. The following table summarizes the components of StarStone U.S.'s assets and liabilities held-for-sale on our consolidated balance sheet as of December 31, 2019: December 31, 2019 (1) ASSETS Fixed maturities, trading, at fair value $ 202,994 Fixed maturities, AFS, at fair value 375,337 Equities, at fair value 3,000 Other investments, at fair value 6,389 Total investments 587,720 Cash and cash equivalents 78,613 Restricted cash and cash equivalents 5,815 Premiums receivable 99,367 Deferred tax assets 15,191 Reinsurance balances recoverable on paid and unpaid losses 530,604 Funds held by reinsured companies 35,861 Deferred acquisition costs 36,992 Goodwill and intangible assets 24,900 Other assets 59,707 TOTAL ASSETS HELD-FOR-SALE $ 1,474,770 LIABILITIES Losses and loss adjustment expenses $ 836,761 Unearned premiums 218,166 Insurance and reinsurance balances payable 22,453 Other liabilities 131,151 TOTAL LIABILITIES HELD-FOR-SALE $ 1,208,531 NET ASSETS HELD-FOR-SALE $ 266,239 (1) Following our decision to sell StarStone U.S. to Core Specialty which was completed on November 30, 2020, the assets and liabilities of StarStone U.S. as of December 31, 2019 were reclassified to held-for-sale on our consolidated balance sheets, in addition to the comparatives being restated since StarStone U.S. qualified as a discontinued operation. 2020 2019 2018 INCOME Net premiums earned $ 291,326 $ 350,814 $ 199,796 Net investment income 12,849 15,606 10,572 Net realized and unrealized gains 5,431 19,385 (5,352) Other income 49 9 10 309,655 385,814 205,026 EXPENSES Net incurred losses and loss adjustment expenses 191,844 258,396 130,303 Acquisition costs 57,640 65,342 14,935 General and administrative expenses 60,236 60,003 58,590 Interest expense 2,066 2,600 2,120 Net foreign exchange (gains) losses (13) 33 24 311,773 386,374 205,972 EARNINGS (LOSS) BEFORE INCOME TAXES (2,118) (560) (946) Income tax benefit 2,255 7,935 2,435 NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES, BEFORE GAIN ON SALE $ 137 $ 7,375 $ 1,489 DISPOSAL Consideration received $ 281,989 $ — $ — Less: Carrying value of subsidiary (277,697) — — Add: Net realized gains on AFS securities and cumulative currency translation adjustments previously recognized in AOCI 11,822 — — Gain on sale of subsidiary $ 16,114 $ — $ — NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES $ 16,251 $ 7,375 $ 1,489 Net loss (earnings) from discontinued operations attributable to noncontrolling interest (8,717) (3,025) (611) NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS $ 7,534 $ 4,350 $ 878 The table below presents a summary of the total income and expenses which have been recognized within our continuing operations for the years ended December 31, 2020, 2019 and 2018, relating to intercompany transactions, primarily intra-group reinsurances, between StarStone U.S. and our subsidiaries: 2020 2019 2018 Total Income $ 11,911 $ 10,672 $ 98,402 Total Expenses (1) (16,397) 62,515 113,952 Net Earnings (Loss) $ 28,308 $ (51,843) $ (15,550) (1) For the year ended December 31, 2020, negative total expenses were driven by favorable loss development on the losses and LAE reserves ceded by StarStone U.S. to our subsidiaries.

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2020
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 the underlying asset categories comprising our short-term and fixed maturity investments classified as trading and AFS and the fixed maturity investments included within our funds held - directly managed balance were as follows as of December 31, 2020 and 2019: 2020 Short-term investments, trading Short-term investments, AFS Fixed maturities, trading Fixed maturities, AFS Fixed maturities, funds held - directly managed Total U.S. government and agency $ — $ 243,556 $ 123,874 $ 474,442 $ 109,176 $ 951,048 U.K. government — — 37,508 13,574 — 51,082 Other government 3,424 3,213 327,437 146,914 21,165 502,153 Corporate 1,705 17,026 3,227,726 1,920,323 519,952 5,686,732 Municipal — — 79,959 30,032 52,678 162,669 Residential mortgage-backed — — 154,471 328,871 70,603 553,945 Commercial mortgage-backed — — 347,225 276,488 230,377 854,090 Asset-backed — — 296,692 204,456 56,312 557,460 Total fixed maturity and short-term investments $ 5,129 $ 263,795 $ 4,594,892 $ 3,395,100 $ 1,060,263 $ 9,319,179 2019 Short-term investments, trading Short-term investments, AFS Fixed maturities, trading Fixed maturities, AFS Fixed maturities, funds held - directly managed Total U.S. government and agency $ — $ 111,583 $ 208,296 $ 269,661 $ 106,537 $ 696,077 U.K. government 24,411 1,069 122,012 14,280 — 161,772 Other government 21,958 387 575,017 84,760 20,734 702,856 Corporate 5,121 13,915 3,959,288 866,557 603,389 5,448,270 Municipal — 1,381 87,451 2,399 49,456 140,687 Residential mortgage-backed — — 215,521 99,188 86,205 400,914 Commercial mortgage-backed — — 534,357 49,046 230,343 813,746 Asset-backed — — 441,393 152,161 76,681 670,235 Total fixed maturity and short-term investments $ 51,490 $ 128,335 $ 6,143,335 $ 1,538,052 $ 1,173,345 $ 9,034,557
Summary of Amortized Cost and Estimated Fair Value of Fixed Maturity and Short-term Investments by Contractual Maturity	The contractual maturities of our short-term and fixed maturity investments, classified as trading and AFS, and the fixed maturity investments included within our funds held - directly managed balance are shown below. Actual maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. As of December 31, 2020 Amortized Cost Fair Value % of Total Fair Value One year or less $ 489,559 $ 494,490 5.3 % More than one year through two years 710,621 726,331 7.8 % More than two years through five years 2,097,923 2,206,020 23.7 % More than five years through ten years 1,974,838 2,151,191 23.1 % More than ten years 1,544,533 1,775,652 19.0 % Residential mortgage-backed 545,628 553,945 5.9 % Commercial mortgage-backed 828,155 854,090 9.2 % Asset-backed 567,638 557,460 6.0 % $ 8,758,895 $ 9,319,179 100.0 %
Credit Ratings Company's Fixed Maturity and Short-Term Investments Available-for-Sale	The following table sets forth the credit ratings of our short-term and fixed maturity investments, classified as trading and AFS, and the fixed maturity investments included within our funds held - directly managed balance as of December 31, 2020: Amortized Fair Value % of Total AAA AA Rated A Rated BBB Non- Not Rated U.S. government and agency $ 935,014 $ 951,048 10.2 % $ 951,048 $ — $ — $ — $ — $ — U.K. government 46,988 51,082 0.6 % — 43,199 7,883 — — — Other government 463,765 502,153 5.4 % 244,041 159,095 42,337 51,413 5,267 — Corporate 5,226,238 5,686,732 61.0 % 172,718 607,796 2,646,602 1,960,971 287,363 11,282 Municipal 145,469 162,669 1.7 % 8,270 78,585 55,631 20,183 — — Residential mortgage-backed 545,628 553,945 5.9 % 544,545 — 2,195 2,615 2,472 2,118 Commercial mortgage-backed 828,155 854,090 9.2 % 591,396 115,114 74,615 61,730 3,961 7,274 Asset-backed 567,638 557,460 6.0 % 239,733 84,058 119,757 89,898 24,014 — Total $ 8,758,895 $ 9,319,179 100.0 % $ 2,751,751 $ 1,087,847 $ 2,949,020 $ 2,186,810 $ 323,077 $ 20,674 % of total fair value 29.5 % 11.7 % 31.6 % 23.5 % 3.5 % 0.2 %
Amortized Cost and Estimated Fair Values of Company's Fixed Maturity and Short-Term Investments Classified as Available-for-Sale	The amortized cost, unrealized gains and losses, allowance for credit losses and fair values of our short-term and fixed maturity investments classified as AFS as of December 31, 2020 were as follows: Gross Unrealized Losses 2020 Amortized Cost Gross Unrealized Gains Non-Credit Related Losses Allowance for Credit Losses (1) Fair Value U.S. government and agency $ 715,527 $ 3,305 $ (834) $ — $ 717,998 U.K. government 12,494 1,080 — — 13,574 Other government 142,459 7,721 (53) — 150,127 Corporate 1,873,184 65,913 (1,567) (181) 1,937,349 Municipal 28,881 1,155 (4) — 30,032 Residential mortgage-backed 326,268 3,292 (689) — 328,871 Commercial mortgage-backed 273,516 5,202 (2,097) (133) 276,488 Asset-backed 204,312 846 (694) (8) 204,456 $ 3,576,641 $ 88,514 $ (5,938) $ (322) $ 3,658,895 (1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 1 - "Significant Accounting Policies" for further details. The amortized cost, unrealized gains and losses and fair values of our short-term and fixed maturity investments classified as AFS as of December 31, 2019 were as follows: 2019 Amortized Gross Gross Fair U.S. government and agency $ 381,488 $ 78 $ (322) $ 381,244 U.K. government 15,067 282 — 15,349 Other government 84,116 1,119 (88) 85,147 Corporate 880,667 3,739 (3,934) 880,472 Municipal 3,770 12 (2) 3,780 Residential mortgage-backed 99,646 221 (679) 99,188 Commercial mortgage-backed 49,219 30 (203) 49,046 Asset-backed 152,153 127 (119) 152,161 $ 1,666,126 $ 5,608 $ (5,347) $ 1,666,387 The following table summarizes our short-term and fixed maturity investments classified as AFS that were in a gross unrealized loss position, for which an allowance for credit losses has not been recorded, as of December 31, 2020: 12 Months or Greater Less Than 12 Months Total 2020 Fair Gross Unrealized Fair Gross Unrealized Fair Gross Unrealized U.S. government and agency $ — $ — $ 55,839 $ (834) $ 55,839 $ (834) UK government — — — — — — Other government — — 7,971 (53) 7,971 (53) Corporate — — 199,048 (1,224) 199,048 (1,224) Municipal — — 1,690 (4) 1,690 (4) Residential mortgage-backed 4,626 (125) 79,149 (564) 83,775 (689) Commercial mortgage-backed 38 (38) 67,094 (1,562) 67,132 (1,600) Asset-backed — — 116,827 (564) 116,827 (564) Total short-term and fixed maturity investments $ 4,664 $ (163) $ 527,618 $ (4,805) $ 532,282 $ (4,968) The following table summarizes our short-term and fixed maturity investments classified as AFS that were in a gross unrealized loss position as of December 31, 2019, aggregated by major security type and length of time in continuous unrealized loss position: 12 Months or Greater Less Than 12 Months Total 2019 Fair Gross Unrealized Fair Gross Unrealized Fair Gross Unrealized U.S. government and agency $ — $ — $ 193,574 $ (322) $ 193,574 $ (322) Other government 1,080 (23) 37,796 (65) 38,876 (88) Corporate 2,754 (306) 338,965 (3,628) 341,719 (3,934) Municipal 128 — 761 (2) 889 (2) Residential mortgage-backed — — 52,005 (679) 52,005 (679) Commercial mortgage-backed — — 35,777 (203) 35,777 (203) Asset-backed — — 101,591 (119) 101,591 (119) Total short-term and fixed maturity investments $ 3,962 $ (329) $ 760,469 $ (5,018) $ 764,431 $ (5,347)
Summary of Allowance for Credit Losses	The following table provides a reconciliation of the beginning and ending allowance for credit losses on our AFS debt securities: December 31, 2020 Other Corporate Residential mortgage-backed Commercial Asset-backed Total Allowance for credit losses, beginning of year $ — $ — $ — $ — $ — $ — Cumulative effect of change in accounting principle (22) (2,987) — (50) — (3,059) Allowances for credit losses on securities for which credit losses were not previously recorded — (10,748) (2) (675) (142) (11,567) Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets — — — — — — Reductions for securities sold during the year 22 2,545 — — — 2,567 Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis — — — — — — (Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period — 11,009 2 592 134 11,737 Allowance for credit losses, end of year $ — $ (181) $ — $ (133) $ (8) $ (322)
Schedule Of Equity Securities	The following table summarizes our equity investments classified as trading as of December 31, 2020 and 2019: 2020 2019 Publicly traded equity investments in common and preferred stocks $ 260,767 $ 327,875 Exchange-traded funds 311,287 133,047 Privately held equity investments in common and preferred stocks 274,741 265,799 $ 846,795 $ 726,721
Other Investments	The following table summarizes our other investments carried at fair value as of December 31, 2020 and 2019: 2020 2019 Hedge funds $ 2,638,339 $ 1,121,904 Fixed income funds 552,541 481,039 Private equity funds 363,103 323,496 Private credit funds 192,319 — Equity funds 190,767 410,149 CLO equity funds 166,523 87,509 CLO equities 128,083 87,555 Others 12,359 6,379 $ 4,244,034 $ 2,518,031 sales process as of December 31, 2020: Less than 1 Year 1-2 years 2-3 years More than 3 years Not Eligible/ Restricted Total Redemption Frequency Hedge funds $ 2,590,164 $ — $ — $ — $ 48,175 $ 2,638,339 Monthly to Bi-annually Fixed income funds 537,055 — — — 15,486 552,541 Daily to Quarterly Equity funds 190,767 — — — — 190,767 Daily to Quarterly Private equity funds — — — — 363,103 363,103 N/A CLO equity funds 94,313 61,741 10,469 — — 166,523 Quarterly to Bi-annually CLO equities 128,083 — — — — 128,083 Daily to Quarterly Private credit funds — 9,250 — 183,069 192,319 N/A Other 12,359 12,359 N/A $ 3,540,382 $ 70,991 $ 10,469 $ — $ 622,192 $ 4,244,034
Equity Method Investments	The table below shows our equity method investments as of December 31, 2020 and 2019: 2020 2019 Ownership % Carrying Value Ownership % Carrying Value Enhanzed Re 47.4 % $ 330,289 47.4 % $ 182,856 Citco (1) 31.9 % 53,022 31.9 % 51,742 Monument Re (2) 20.0 % 193,716 20.0 % 60,598 Clear Spring — % — 20.0 % 10,645 Core Specialty 25.2 % 235,000 — % — Other 27% 20,268 30% 20,436 $ 832,295 $ 326,277 (1 ) We own 31.9% of the common shares in HH CTCO Holdings Limited which in turn owns 15.4% of the convertible preferred shares, amounting to a 6.2% interest in the total equity of Citco III Limited ("Citco"). (2) We own 20.0% of the common shares in Monument Re as well as different classes of preferred shares which have fixed dividend yields and whose balances are included in the Investment amount.
Funds Held, Directly Managed, Carrying Values of Assets	The following table summarizes the components of the funds held - directly managed as of December 31, 2020 and 2019: 2020 2019 Fixed maturity investments, trading $ 1,060,263 $ 1,173,345 Cash and cash equivalents 9,067 10,296 Other assets 5,560 3,911 $ 1,074,890 $ 1,187,552
Funds Held, Directly Managed, Fair Value To Amortized Cost	The following table summarizes the short-term and fixed maturity investment components of funds held - directly managed as of December 31, 2020 and 2019: 2020 2019 Funds held - Directly Managed - Fair Value Option Funds held - Directly Managed - Variable Return Total Funds held - Directly Managed - Fair Value Option Funds held - Directly Managed - Variable Return Total Short-term and fixed maturity investments, at amortized cost $ 106,938 $ 859,403 $ 966,341 $ 185,859 $ 940,194 $ 1,126,053 Net unrealized gains (losses): Change in fair value - fair value option accounting 9,693 — 9,693 5,438 — 5,438 Change in fair value - embedded derivative accounting — 84,229 84,229 — 41,854 41,854 Short-term and fixed maturity investments within funds held - directly managed, at fair value $ 116,631 $ 943,632 $ 1,060,263 $ 191,297 $ 982,048 $ 1,173,345
Investment Income	Major categories of net investment income for the years ended December 31, 2020, 2019 and 2018 are summarized as follows: 2020 2019 2018 Fixed maturity investments $ 198,988 $ 217,886 $ 178,213 Short-term investments and cash and cash equivalents 4,843 15,609 11,692 Funds held 33,920 22,580 11,640 Funds held – directly managed 34,563 38,173 37,623 Investment income from fixed maturities and cash and cash equivalents 272,314 294,248 239,168 Equity investments 19,240 16,671 5,397 Other investments 27,153 11,792 26,214 Investment income from equities and other investments 46,393 28,463 31,611 Gross investment income 318,707 322,711 270,779 Investment expenses (15,890) (14,440) (9,081) Net investment income $ 302,817 $ 308,271 $ 261,698
Realized Gain (Loss) on Investments	Components of net realized and unrealized gains (losses) for the years ended December 31, 2020, 2019 and 2018 were as follows: 2020 2019 2018 Net realized gains (losses) on sale: Gross realized gains on fixed maturity securities, AFS $ 26,313 $ 4,844 $ 27 Gross realized losses on fixed maturity securities, AFS (7,801) (905) (90) Decrease in allowance for expected credit losses on fixed maturity securities, AFS 170 — — Net realized gains (losses) on fixed maturity securities, trading 126,945 81,011 (27,408) Net realized gains (losses) on fixed maturity securities in funds held - directly managed 8,798 1,495 (3,940) Net realized gains (losses) on equity investments 24,282 (374) 4,016 Net realized investment gains on investment derivatives 144 — — Total net realized gains (losses) on sale 178,851 86,071 (27,395) Net unrealized gains (losses): Fixed maturity securities, trading 101,022 341,130 (159,594) Fixed maturity securities in funds held - directly managed 50,837 88,053 (46,257) Equity investments (25,752) 55,359 (9,831) Other investments 1,336,343 441,702 (164,455) Investment derivatives 718 (349) — Total net unrealized gains (losses) 1,463,168 925,895 (380,137) Net realized and unrealized gains (losses) $ 1,642,019 $ 1,011,966 $ (407,532)
Unrealized Gain (Loss) on Investments	Components of net realized and unrealized gains (losses) for the years ended December 31, 2020, 2019 and 2018 were as follows: 2020 2019 2018 Net realized gains (losses) on sale: Gross realized gains on fixed maturity securities, AFS $ 26,313 $ 4,844 $ 27 Gross realized losses on fixed maturity securities, AFS (7,801) (905) (90) Decrease in allowance for expected credit losses on fixed maturity securities, AFS 170 — — Net realized gains (losses) on fixed maturity securities, trading 126,945 81,011 (27,408) Net realized gains (losses) on fixed maturity securities in funds held - directly managed 8,798 1,495 (3,940) Net realized gains (losses) on equity investments 24,282 (374) 4,016 Net realized investment gains on investment derivatives 144 — — Total net realized gains (losses) on sale 178,851 86,071 (27,395) Net unrealized gains (losses): Fixed maturity securities, trading 101,022 341,130 (159,594) Fixed maturity securities in funds held - directly managed 50,837 88,053 (46,257) Equity investments (25,752) 55,359 (9,831) Other investments 1,336,343 441,702 (164,455) Investment derivatives 718 (349) — Total net unrealized gains (losses) 1,463,168 925,895 (380,137) Net realized and unrealized gains (losses) $ 1,642,019 $ 1,011,966 $ (407,532)
Reconciliation to Comprehensive Income	The following table provides a reconciliation of the gross realized gains and losses and credit recoveries (losses) on our AFS fixed maturity debt securities that arose during the years ended December 31, 2020, 2019 and 2018 within our continuing and discontinued operations and the offsetting reclassification adjustments included within our consolidated statements of comprehensive income: 2020 2019 2018 Included within continuing operations: Gross realized gains on fixed maturity securities, AFS $ 26,313 $ 4,844 $ 27 Gross realized losses on fixed maturity securities, AFS (7,801) (905) (90) Tax effect (1,623) — — Included within discontinued operations: Gross realized gains on fixed maturity securities, AFS 1,374 12 — Gross realized losses on fixed maturity securities, AFS (120) (57) — Tax effect (110) — — Total reclassification adjustment for net realized gains (losses) included in net earnings $ 18,033 $ 3,894 $ (63) Included within continuing operations: Credit recoveries (losses) on fixed maturity securities, AFS $ 170 $ — $ — Tax effect 3 — — Included within discontinued operations: Credit recoveries (losses) on fixed maturity securities, AFS 329 — — Tax effect 7 — — Total reclassification adjustment for change in allowance for credit losses recognized in net earnings $ 509 $ — $ — The following table presents details amounts reclassified from accumulated other comprehensive income: Details about AOCI components 2020 2019 2018 Affected Line Item in Statement where Net Earnings are presented Unrealized gains (losses) on fixed income available-for-sale investments 18,682 3,894 (63) Net realized and unrealized gains (losses) 16,591 — — Net earnings from discontinued operations 35,273 3,894 (63) Total before tax (4,875) — — Income tax (expense) 30,398 3,894 (63) Net of tax Currency translation adjustment on disposal of subsidiary (34) — — Net earnings from discontinued operations Total reclassifications for the period, net of tax 30,364 3,894 (63)
Schedule of Carrying Value of Restricted Investments	The carrying value of our restricted assets, including restricted cash of $472.0 million and $346.9 million, as of December 31, 2020 and 2019, respectively, was as follows: 2020 2019 Collateral in trust for third party agreements $ 4,924,866 $ 4,103,847 Assets on deposit with regulatory authorities 131,283 309,659 Collateral for secured letter of credit facilities 104,627 132,670 Funds at Lloyd's (1) 260,914 639,316 $ 5,421,690 $ 5,185,492 (1) Our businesses include three Lloyd's syndicates as at December 31, 2020. Lloyd's determines the required capital principally through the annual business plan of each syndicate. This capital is referred to as "Funds at Lloyd's" and will be drawn upon in the event that a syndicate has a loss that cannot be funded from other sources. We also utilize unsecured letters of credit for Funds at Lloyd's, as described in Note 15 - "Debt Obligations and Credit Facilities".

Derivatives and Hedging Instr_2

Derivatives and Hedging Instruments (Tables)	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Estimated Fair Value and Unrealized Gains (Losses) on Derivative Instruments	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 of December 31, 2020 and 2019: 2020 2019 Fair Value Fair Value Gross Notional Amount Assets Liabilities Gross Notional Amount Assets Liabilities Foreign currency forward - AUD $ 73,852 $ 13 $ 5,060 $ 64,620 $ 52 $ 2,033 Foreign currency forward - EUR 217,168 205 8,889 112,284 246 1,635 Foreign currency forward - GBP 312,671 951 14,998 318,387 344 7,784 Total qualifying hedges $ 603,691 $ 1,169 $ 28,947 $ 495,291 $ 642 $ 11,452 The following table presents the net gains and losses deferred in the cumulative translation adjustment ("CTA") account, which is a component of AOCI, in shareholders' equity, relating to our foreign currency forward exchange rate contracts for the years ended December 31, 2020, 2019 and 2018: Amount of Gains (Losses) Deferred in AOCI 2020 2019 2018 Foreign currency forward - AUD $ (6,792) $ (722) $ 3,438 Foreign currency forward - EUR (15,026) 1,817 1,000 Foreign currency forward - GBP (8,457) (16,423) — Total qualifying hedges $ (30,275) $ (15,328) $ 4,438 The following tables present the gross notional amounts and estimated fair values recorded within other assets and other liabilities related to our non-qualifying foreign currency forward exchange rate hedging relationships as of December 31, 2020 and 2019: December 31, 2020 December 31, 2019 Fair Value Fair Value Gross Notional Amount Assets Liabilities Gross Notional Amount Assets Liabilities Foreign currency forward - AUD $ 28,848 $ 882 $ 2,847 $ 913 $ 839 $ 892 Foreign currency forward - CAD 64,224 10 1,764 66,266 10 1,482 Foreign currency forward - EUR 43,531 1,782 41 74,444 507 1,440 Foreign currency forward - GBP 2,731 161 404 11,940 13 292 Total non-qualifying hedges $ 139,334 $ 2,835 $ 5,056 $ 153,563 $ 1,369 $ 4,106 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 years ended December 31, 2020, 2019, and 2018: Gains (losses) on non-qualifying hedges charged to earnings 2020 2019 2018 Foreign currency forward - AUD $ (2,388) $ 1,523 $ 4,958 Foreign currency forward - CAD (879) (2,079) 9,311 Foreign currency forward - EUR 1,871 1,759 2,296 Foreign currency forward - GBP (1,558) 12,004 15,078 Net gains (losses) on non-qualifying hedges $ (2,954) $ 13,207 $ 31,643 The following table presents the gross notional amounts and estimated fair values recorded within other assets and other liabilities related to our credit default swaps, government bond futures contracts and currency forward contracts: December 31, 2020 Fair Value Gross Notional Amount Assets Liabilities Futures contracts - long positions $ 34,502 $ 32 $ 5 Futures contracts - short positions (32,316) 6 121 Currency forward contracts - long positions - USD 1,428 — 13 Currency forward contracts - short positions - USD (3,233) 60 — Currency forward contracts - long positions - GBP 1,278 19 — Currency forward contracts - short positions - GBP (4,418) 12 — Total $ (2,759) $ 129 $ 139
Derivative Instruments, Gain (Loss)	The following table presents the amounts of the net gains included in earnings related to our credit default swaps, government bond futures contracts and currency forward contracts: 2020 Credit default swaps $ 181 Futures contracts (127) Currency forward contracts 572 Total net gains $ 626

Reinsurance Balances Recovera_2

Reinsurance Balances Recoverable on Paid and Unpaid Losses (Tables)	12 Months Ended
	Dec. 31, 2020
Insurance [Abstract]
Summary of Reinsurance Reserves Recoverable	The following tables provide the total reinsurance balances recoverable on paid and unpaid losses. December 31, 2020 Non-life StarStone Total Recoverable from reinsurers on unpaid: Outstanding losses $ 938,231 $ 263,638 $ 1,201,869 IBNR 508,082 139,761 647,843 ULAE 16,688 — 16,688 Fair value adjustments - acquired companies (14,014) (1,339) (15,353) Fair value adjustments - fair value option (21,427) — (21,427) Total reinsurance reserves recoverable 1,427,560 402,060 1,829,620 Paid losses recoverable 172,309 87,234 259,543 Total $ 1,599,869 $ 489,294 $ 2,089,163 Reconciliation to Consolidated Balance Sheet: Reinsurance balances recoverable on paid and unpaid losses $ 1,079,039 $ 489,294 $ 1,568,333 Reinsurance balances recoverable on paid and unpaid losses - fair value option 520,830 — 520,830 Total $ 1,599,869 $ 489,294 $ 2,089,163 December 31, 2019 Non-life Atrium StarStone Total Recoverable from reinsurers on unpaid: Outstanding losses $ 972,293 $ 9,011 $ 264,131 $ 1,245,435 IBNR 673,059 19,286 93,185 785,530 Fair value adjustments - acquired companies (13,652) 519 (2,122) (15,255) Fair value adjustments - fair value option (88,086) — — (88,086) Total reinsurance reserves recoverable 1,543,614 28,816 355,194 1,927,624 Paid losses recoverable 181,375 1,541 70,594 253,510 Total $ 1,724,989 $ 30,357 $ 425,788 $ 2,181,134 Reconciliation to Consolidated Balance Sheet: Reinsurance balances recoverable on paid and unpaid losses $ 1,029,471 $ 30,357 $ 425,788 $ 1,485,616 Reinsurance balances recoverable on paid and unpaid losses - fair value option 695,518 — — 695,518 Total $ 1,724,989 $ 30,357 $ 425,788 $ 2,181,134 The following tables show our gross and net balances recoverable from our reinsurers as well as the related allowance for estimated uncollectible reinsurance broken down by the credit ratings of our reinsurers. The majority of the allowance for estimated uncollectible reinsurance relates to the Non-life Run-off segment. December 31, 2020 Gross Allowance for estimated uncollectible reinsurance Net Provisions as a Reinsurers rated A- or above $ 1,464,529 $ 60,801 $ 1,403,728 4.2 % Reinsurers rated below A-, secured 608,999 — 608,999 — % Reinsurers rated below A-, unsecured 152,757 76,321 76,436 50.0 % Total $ 2,226,285 $ 137,122 $ 2,089,163 6.2 % December 31, 2019 Gross Allowance for estimated uncollectible reinsurance Net Provisions as a Reinsurers rated A- or above $ 1,731,270 $ 43,427 $ 1,687,843 2.5 % Reinsurers rated below A-, secured 463,840 — 463,840 — % Reinsurers rated below A-, unsecured 133,663 104,212 29,451 78.0 % Total $ 2,328,773 $ 147,639 $ 2,181,134 6.3 % The following tables provide a summary of net premiums written and earned for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Premiums Premiums Premiums Premiums Premiums Premiums Non-life Run-off Gross $ 5,191 $ 71,522 $ (25,069) $ 197,009 $ (8,910) $ 25,230 Ceded (2,204) (12,827) (269) (28,513) (307) (15,803) Net $ 2,987 $ 58,695 $ (25,338) $ 168,496 $ (9,217) $ 9,427 Atrium Gross $ 206,656 $ 197,492 $ 192,373 $ 182,678 $ 171,494 $ 164,428 Ceded (23,462) (22,099) (20,017) (18,619) (18,006) (18,113) Net $ 183,194 $ 175,393 $ 172,356 $ 164,059 $ 153,488 $ 146,315 StarStone Gross $ 326,695 $ 441,015 $ 472,815 $ 549,299 $ 622,570 $ 647,218 Ceded (93,493) (122,900) (93,292) (98,187) (144,561) (132,055) Net $ 233,202 $ 318,115 $ 379,523 $ 451,112 $ 478,009 $ 515,163 Other Gross $ 13,441 $ 19,889 $ 18,534 $ 20,544 $ 32,378 $ 25,237 Ceded — — (22) (164) (311) (363) Net $ 13,441 $ 19,889 $ 18,512 $ 20,380 $ 32,067 $ 24,874 Total Gross $ 551,983 $ 729,918 $ 658,653 $ 949,530 $ 817,532 $ 862,113 Ceded (119,159) (157,826) (113,600) (145,483) (163,185) (166,334) Net $ 432,824 $ 572,092 $ 545,053 $ 804,047 $ 654,347 $ 695,779
Reinsurance Balances Recoverable by Reinsurer	December 31, 2020 Non-life StarStone Total % of Top 10 reinsurers $ 1,036,676 $ 327,917 $ 1,364,593 65.3 % Other reinsurers > $1 million 539,428 158,174 697,602 33.4 % Other reinsurers < $1 million 23,765 3,203 26,968 1.3 % Total $ 1,599,869 $ 489,294 $ 2,089,163 100.0 % December 31, 2019 Non-life Atrium StarStone Total % of Top 10 reinsurers $ 1,154,110 $ 22,051 $ 295,443 $ 1,471,604 67.4 % Other reinsurers > $1 million 551,636 7,761 129,335 688,732 31.6 % Other reinsurers < $1 million 19,243 545 1,010 20,798 1.0 % Total $ 1,724,989 $ 30,357 $ 425,788 $ 2,181,134 100.0 % December 31, 2020 December 31, 2019 Information regarding top ten reinsurers: Number of top 10 reinsurers rated A- or better 7 8 Number of top 10 non-rated reinsurers (1) 3 2 Reinsurers rated A- or better in top 10 $ 863,819 $ 1,199,479 Non-rated reinsurers in top 10 (1) 500,774 272,125 Total top 10 reinsurance recoverables $ 1,364,593 $ 1,471,604 Single reinsurers that represent 10% or more of total reinsurance balance recoverables as of December 31, 2020 and 2019: Hannover Ruck SE (2) $ — $ 259,077 Lloyd's Syndicates (3) $ 331,118 $ 396,246 Michigan Catastrophic Claims Association (4) $ 229,374 $ — (1) The reinsurance balances recoverable from the three and two non-rated top 10 reinsurers as of December 31, 2020 and 2019, respectively, was comprised of: • $229.4 million and $190.8 million as of December 31, 2020 and December 31, 2019 respectively, due from a U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state; • $73.8 million and $81.4 million as of December 31, 2020 and December 31, 2019 respectively, due from a reinsurer who has provided us with security in the form of pledged assets in trust for the full amount of the recoverable balance; and • $208.4 million as of December 31, 2020 due from Enhanzed Re, an equity method investee to whom some of our subsidiaries have retroceded their exposures through quota share reinsurance agreements as discussed in Note 21 - "Related Party Transactions". These quota share reinsurance agreements are written on a funds withheld basis with our subsidiaries retaining the retrocession premium consideration, to secure the full amount of the recoverable balances due from Enhanzed Re. (2) Hannover Ruck SE is rated AA- by Standard & Poor’s and A+ by A.M. Best. The transaction described in Note 4 - "Significant New Business" had the effect of reducing the balances due from this reinsurer to below 10% of the total reinsurance balances recoverable as of December 31, 2020. (3) Lloyd's Syndicates are rated A+ by Standard & Poor's and A by A.M. Best. (4) U.S. state backed reinsurer that is supported by assessments on active auto writers operating within the state.
Summary of Reinsurance Recoverable, Allowance for Credit Loss	The table below provides a reconciliation of the beginning and ending allowance for estimated uncollectible reinsurance balances for the years ended December 31, 2020 and 2019: 2020 2019 Allowance for estimated uncollectible reinsurance, beginning of year $ 147,639 $ 156,732 Cumulative effect of change in accounting principle (195) — Effect of exchange rate movement 700 (887) Current period change in the allowance (381) 2,077 Write-offs charged against the allowance (9,625) (9,871) Recoveries collected (1,016) (412) Allowance for estimated uncollectible reinsurance, end of year $ 137,122 $ 147,639

Deferred Charge Assets and De_2

Deferred Charge Assets and Deferred Gain Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Insurance [Abstract]
Deferred Charge Assets	The following table presents a reconciliation of the deferred charge assets for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Beginning carrying value $ 272,462 $ 86,585 $ 80,192 Recorded during the year 11,746 224,504 20,174 Amortization (45,606) (38,627) (13,781) Ending carrying value $ 238,602 $ 272,462 $ 86,585
Deferred Gain Liabilities	Deferred gain liabilities are included in other liabilities on our consolidated balance sheets. The following table presents a reconciliation of the deferred gain liabilities for the years ended December 31, 2020 and 2019: 2020 2019 Beginning carrying value $ 12,875 $ — Recorded during the year 9,365 13,758 Amortization (2,360) (883) Ending carrying value $ 19,880 $ 12,875

Losses and Loss Adjustment Ex_2

Losses and Loss Adjustment Expenses (Tables)	12 Months Ended
	Dec. 31, 2020
Insurance [Abstract]
Total Losses and Loss Adjustment Expense Liabilities, and Reconciliation of Beginning and Ending Balances	The following tables summarize the liability for losses and LAE by segment and for our other activities. 2020 Non-life StarStone Other Total Outstanding losses $ 4,440,425 $ 677,220 $ 10,204 $ 5,127,849 IBNR 4,641,500 615,963 20,040 5,277,503 Fair value adjustments - acquired companies (142,854) (329) — (143,183) Fair value adjustments - fair value option (54,589) — — (54,589) ULAE 350,600 35,102 — 385,702 Total $ 9,235,082 $ 1,327,956 $ 30,244 $ 10,593,282 Reconciliation to Consolidated Balance Sheet: Loss and loss adjustment expenses $ 6,782,162 $ 1,327,956 $ 30,244 $ 8,140,362 Loss and loss adjustment expenses, at fair value 2,452,920 — — 2,452,920 Total $ 9,235,082 $ 1,327,956 $ 30,244 $ 10,593,282 2019 Non-life Atrium StarStone Other Total Outstanding losses $ 4,407,082 $ 89,141 $ 743,830 $ 9,512 $ 5,249,565 IBNR 3,945,407 136,543 556,134 13,565 4,651,649 Fair value adjustments- acquired companies (170,689) 3,700 (522) — (167,511) Fair value adjustments - fair value option (217,933) — — — (217,933) ULAE 331,494 2,288 18,852 — 352,634 Total $ 8,295,361 $ 231,672 $ 1,318,294 $ 23,077 $ 9,868,404 Reconciliation to Consolidated Balance Sheet: Loss and loss adjustment expenses $ 5,674,239 $ 231,672 $ 1,318,294 $ 23,077 $ 7,247,282 Loss and loss adjustment expenses, at fair value 2,621,122 — — — 2,621,122 Total $ 8,295,361 $ 231,672 $ 1,318,294 $ 23,077 $ 9,868,404 The table below provides a consolidated reconciliation of the beginning and ending liability for losses and LAE. 2020 2019 2018 Balance as of January 1 $ 9,868,404 $ 9,048,796 $ 7,100,488 Less: reinsurance reserves recoverable 1,927,624 1,708,272 1,693,028 Less: net deferred charge assets and gain liabilities on retroactive reinsurance 259,587 86,585 80,192 Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances (1) 643 — — Net balance as of January 1 7,680,550 7,253,939 5,327,268 Net incurred losses and LAE: Current period 405,178 580,074 533,081 Prior periods 10,748 34,105 (209,359) Total net incurred losses and LAE 415,926 614,179 323,722 Net paid losses: Current period (71,989) (179,461) (176,172) Prior periods (1,413,500) (1,609,009) (1,158,614) Total net paid losses (1,485,489) (1,788,470) (1,334,786) Effect of exchange rate movement 119,663 47,812 (145,243) Acquired on purchase of subsidiaries — 686 1,310,874 Assumed business 2,186,024 1,586,307 1,772,104 Ceded business (154,926) (33,260) — Reclassification to assets and liabilities held-for-sale (216,808) — — Net balance as of December 31 8,544,940 7,681,193 7,253,939 Plus: reinsurance reserves recoverable (2) 1,829,620 1,927,624 1,708,272 Plus: net deferred charge assets and gain liabilities on retroactive reinsurance 218,722 259,587 86,585 Balance as of December 31 $ 10,593,282 $ 9,868,404 $ 9,048,796 (1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details. This amount excludes $0.4 million related to the adoption impact of ASU 2016-13 on StarStone U.S., which has been classified as a discontinued operation with the related assets and liabilities disclosed as held-for-sale on our consolidated balance sheets. (2) Net of allowance for estimated uncollectible reinsurance. The table below provides a reconciliation of the beginning and ending reserves for losses and LAE for the Non-life Run-off segment. 2020 2019 2018 Balance as of January 1 $ 8,295,361 $ 7,540,662 $ 5,949,472 Less: reinsurance reserves recoverable 1,543,614 1,366,123 1,377,485 Less: net deferred charge assets and gain liabilities on retroactive reinsurance 259,587 86,585 80,192 Plus: cumulative effect of change in accounting principal on allowance for estimated uncollectible reinsurance (1) 703 — — Net balance as of January 1 6,492,863 6,087,954 4,491,795 Net incurred losses and LAE: Current period 30,165 123,559 12,451 Prior periods 14,830 (71,934) (318,518) Total net incurred losses and LAE 44,995 51,625 (306,067) Net paid losses: Current period (9,990) (64,820) (5) Prior periods (1,064,911) (1,182,804) (838,812) Total net paid losses (1,074,901) (1,247,624) (838,817) Effect of exchange rate movement 94,745 46,472 (132,632) Acquired on purchase of subsidiaries — 686 1,111,839 Assumed business 2,186,024 1,586,307 1,761,836 Ceded business (154,926) (33,260) — Net balance as of December 31 7,588,800 6,492,160 6,087,954 Plus: reinsurance reserves recoverable (2) 1,427,560 1,543,614 1,366,123 Plus: net deferred charge assets and gain liabilities on retroactive reinsurance 218,722 259,587 86,585 Balance as of December 31 $ 9,235,082 $ 8,295,361 $ 7,540,662 (1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details. (2) Net of allowance for estimated uncollectible reinsurance. The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Balance as of January 1 $ 231,672 $ 241,284 $ 240,873 Less: reinsurance reserves recoverable 28,816 38,768 40,531 Less: cumulative effect of change in accounting principal on allowance for estimated uncollectible reinsurance (1) 851 — — Net balance as of January 1 202,005 202,516 200,342 Net incurred losses and LAE: Current period 93,471 85,027 83,627 Prior periods (6,245) (7,751) (13,817) Total net incurred losses and LAE 87,226 77,276 69,810 Net paid losses: Current period (33,724) (34,617) (35,537) Prior periods (40,196) (43,572) (28,969) Total net paid losses (73,920) (78,189) (64,506) Effect of exchange rate movement 1,497 1,253 (3,130) Reclassification to assets and liabilities held-for-sale (216,808) — — Net balance as of December 31 — 202,856 202,516 Plus: reinsurance reserves recoverable (2) — 28,816 38,768 Balance as of December 31 $ — $ 231,672 $ 241,284 (1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details. (2) Net of allowance for estimated uncollectible reinsurance. The table below provides a reconciliation of the beginning and ending liability for losses and LAE for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Balance as of January 1 $ 1,318,294 $ 1,247,989 $ 910,143 Less: reinsurance reserves recoverable 355,194 303,381 275,012 Less: cumulative effect of change in accounting principal on allowance for estimated uncollectible reinsurance (1) 495 — — Net balance as of January 1 962,605 944,608 635,131 Net incurred losses and LAE: Current period 263,562 354,884 422,191 Prior periods 3,176 114,356 120,889 Total net incurred losses and LAE 266,738 469,240 543,080 Net paid losses: Current period (26,831) (75,458) (137,390) Prior periods (300,037) (375,377) (289,981) Total net paid losses (326,868) (450,835) (427,371) Effect of exchange rate movement 23,421 87 (9,481) Acquired on purchase of subsidiaries — — 192,981 Assumed business — — 10,268 Ceded business — — — Net balance as of December 31 925,896 963,100 944,608 Plus: reinsurance reserves recoverable (2) 402,060 355,194 303,381 Balance as of December 31 $ 1,327,956 $ 1,318,294 $ 1,247,989 (1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details. (2) Net of allowance for estimated uncollectible reinsurance.
Schedule of Incurred Losses	The tables below provide the components of net incurred losses and LAE by segment and for our other activities. 2020 Non-life Atrium StarStone Other Total Net losses paid $ 1,074,901 $ 73,920 $ 326,868 $ 9,800 $ 1,485,489 Net change in case and LAE reserves (1) (453,080) 7,245 (95,044) 692 (540,187) Net change in IBNR reserves (2) (718,414) 6,661 17,654 6,475 (687,624) Increase (reduction) in estimates of net ultimate losses (96,593) 87,826 249,478 16,967 257,678 Increase (reduction) in provisions for unallocated LAE (3) (48,765) (29) 17,244 — (31,550) Amortization of deferred charge assets and deferred gain liabilities (4) 42,640 — 606 — 43,246 Amortization of fair value adjustments (5) 28,667 (571) (590) — 27,506 Changes in fair value - fair value option (6) 119,046 — — — 119,046 Net incurred losses and LAE $ 44,995 $ 87,226 $ 266,738 $ 16,967 $ 415,926 2019 Non-life Atrium StarStone Other Total Net losses paid $ 1,247,624 $ 78,189 $ 450,835 $ 11,822 $ 1,788,470 Net change in case and LAE reserves (1) (530,891) 3,534 (4,686) 3,460 (528,583) Net change in IBNR reserves (2) (812,699) (4,782) 22,021 756 (794,704) Increase (reduction) in estimates of net ultimate losses (95,966) 76,941 468,170 16,038 465,183 Increase (reduction) in provisions for unallocated LAE (3) (57,404) — 902 — (56,502) Amortization of deferred charge assets and deferred gain liabilities (4) 37,744 — — — 37,744 Amortization of fair value adjustments (5) 50,070 335 168 — 50,573 Changes in fair value - fair value option (6) 117,181 — — — 117,181 Net incurred losses and LAE $ 51,625 $ 77,276 $ 469,240 $ 16,038 $ 614,179 2018 Non-life Atrium StarStone Other Total Net losses paid $ 838,817 $ 64,506 $ 427,371 $ 4,092 $ 1,334,786 Net change in case and LAE reserves (1) (547,420) 6,331 63,861 4,808 (472,420) Net change in IBNR reserves (2) (565,385) 4,091 46,501 7,999 (506,794) Increase (reduction) in estimates of net ultimate losses (273,988) 74,928 537,733 16,899 355,572 Increase (reduction) in provisions for unallocated LAE (3) (65,401) — 5,613 — (59,788) Amortization of deferred charge assets and deferred gain liabilities (4) 13,781 — — — 13,781 Amortization of fair value adjustments (5) 12,877 (5,118) (266) — 7,493 Changes in fair value - fair value option (6) 6,664 — — — 6,664 Net incurred losses and LAE $ (306,067) $ 69,810 $ 543,080 $ 16,899 $ 323,722 (1) Comprises the movement during the year in specific case reserve liabilities as a result of claims settlements or changes advised to us by our policyholders and attorneys, less changes in case reserves recoverable advised by us to our reinsurers as a result of the settlement or movement of assumed claims. (2) Represents the gross change in our actuarial estimates of IBNR, less amounts recoverable. (3) Represents the change in the estimate of the total future costs to administer the claims. (4) Relates to the amortization of deferred charge assets and deferred gain liabilities on retroactive reinsurance contracts. (5) Relates to the amortization of fair value adjustments associated with the acquisition of companies. . Net incurred losses and LAE in the Non-life Run-off segment were as follows: 2020 2019 2018 Prior Current Total Prior Current Total Prior Current Total Net losses paid $ 1,064,911 $ 9,990 $ 1,074,901 $ 1,182,804 $ 64,820 $ 1,247,624 $ 838,812 $ 5 $ 838,817 Net change in case and LAE reserves (1) (449,610) (3,470) (453,080) (553,996) 23,105 (530,891) (552,124) 4,704 (547,420) Net change in IBNR reserves (2) (742,417) 24,003 (718,414) (847,893) 35,194 (812,699) (573,127) 7,742 (565,385) Increase (reduction) in estimates of net ultimate losses (127,116) 30,523 (96,593) (219,085) 123,119 (95,966) (286,439) 12,451 (273,988) Increase (reduction) in provisions for unallocated LAE (3) (48,407) (358) (48,765) (57,844) 440 (57,404) (65,401) — (65,401) Amortization of deferred charge assets and deferred gain liabilities (4) 42,640 — 42,640 37,744 — 37,744 13,781 — 13,781 Amortization of fair value adjustments (5) 28,667 — 28,667 50,070 — 50,070 12,877 — 12,877 Changes in fair value - fair value option (6) 119,046 — 119,046 117,181 — 117,181 6,664 — 6,664 Net incurred losses and LAE $ 14,830 $ 30,165 $ 44,995 $ (71,934) $ 123,559 $ 51,625 $ (318,518) $ 12,451 $ (306,067) (1) Comprises the movement during the year in specific case reserve liabilities as a result of claims settlements or changes advised to us by our policyholders and attorneys, less changes in case reserves recoverable advised by us to our reinsurers as a result of the settlement or movement of assumed claims. (2) Represents the gross change in our actuarial estimates of IBNR, less amounts recoverable. (3) Represents the change in the estimate of the total future costs to administer the claims. (4) Relates to the amortization of deferred charge assets and deferred gain liabilities on retroactive reinsurance contracts. (5) Relates to the amortization of fair value adjustments associated with the acquisition of companies. (6) Represents the changes in the fair value of liabilities related to our assumed retroactive reinsurance agreements for which we have elected the fair value option. Net incurred losses and LAE in the Atrium segment for the years ended December 31, 2020, December 31, 2019 and 2018 were as follows: 2020 2019 2018 Prior Current Total Prior Current Total Prior Current Total Net losses paid $ 40,196 $ 33,724 $ 73,920 $ 43,572 $ 34,617 $ 78,189 $ 28,969 $ 35,537 $ 64,506 Net change in case and LAE reserves (1) (14,145) 21,390 7,245 (13,278) 16,812 3,534 (10,161) 16,492 6,331 Net change in IBNR reserves (2) (31,773) 38,434 6,661 (38,380) 33,598 (4,782) (27,507) 31,598 4,091 Increase (reduction) in estimates of net ultimate losses (5,722) 93,548 87,826 (8,086) 85,027 76,941 (8,699) 83,627 74,928 Increase (reduction) in provisions for unallocated LAE (3) 48 (77) (29) — — — — — — Amortization of fair value adjustments (4) (571) — (571) 335 — 335 (5,118) — (5,118) Net incurred losses and LAE $ (6,245) $ 93,471 $ 87,226 $ (7,751) $ 85,027 $ 77,276 $ (13,817) $ 83,627 $ 69,810 (1) Comprises the movement during the year in specific case reserve liabilities as a result of claims settlements or changes advised to us by our policyholders and attorneys, less changes in case reserves recoverable advised by us to our reinsurers as a result of the settlement or movement of assumed claims. (2) Represents the gross change in our actuarial estimates of IBNR, less amounts recoverable. (3) Represents the change in the estimate of the total future costs to administer the claims. (4) Relates to the amortization of fair value adjustments associated with the acquisition of companies. Net incurred losses and LAE in the StarStone segment for the years ended December 31, 2020, December 31, 2019 and 2018 were as follows: 2020 2019 2018 Prior Current Total Prior Current Total Prior Current Total Net losses paid $ 300,037 $ 26,831 $ 326,868 $ 375,377 $ 75,458 $ 450,835 $ 289,981 $ 137,390 $ 427,371 Net change in case and LAE reserves (1) (130,502) 35,458 (95,044) (95,183) 90,497 (4,686) (77,821) 141,682 63,861 Net change in IBNR reserves (2) (165,909) 183,563 17,654 (163,340) 185,361 22,021 (87,963) 134,464 46,501 Increase in estimates of net ultimate losses 3,626 245,852 249,478 116,854 351,316 468,170 124,197 413,536 537,733 Increase (reduction) in provisions for unallocated LAE (3) (466) 17,710 17,244 (2,666) 3,568 902 (3,042) 8,655 5,613 Amortization of deferred charge assets and deferred gain liabilities (4) 606 — 606 — — — — — — Amortization of fair value adjustments (5) (590) — (590) 168 — 168 (266) — (266) Net incurred losses and LAE $ 3,176 $ 263,562 $ 266,738 $ 114,356 $ 354,884 $ 469,240 $ 120,889 $ 422,191 $ 543,080 (1) Comprises the movement during the year in specific case reserve liabilities as a result of claims settlements or changes advised to us by our policyholders and attorneys, less changes in case reserves recoverable advised by us to our reinsurers as a result of the settlement or movement of assumed claims. (2) Represents the gross change in our actuarial estimates of IBNR, less amounts recoverable. (3) Represents the change in the estimate of the total future costs to administer the claims. (4) Relates to the amortization of deferred charge assets and deferred gain liabilities on retroactive reinsurance contracts. (5) Relates to the amortization of fair value adjustments associated with the acquisition of companies.
Schedule of Gross and Net Losses and LAE Reserves by Category	The following table shows the components of the 2020 reduction in estimates of net ultimate losses related to prior periods by line of business for the Non-life Run-off segment. 2020 Net losses paid Net change in case and LAE reserves Net change in IBNR reserves Increase (reduction) in estimates of net ultimate losses Asbestos $ 132,853 $ (1,300) $ (150,054) $ (18,501) Environmental 23,866 (266) (36,362) (12,762) General Casualty 170,502 (68,744) (127,421) (25,663) Workers' Compensation 142,790 (176,927) (149,198) (183,335) Marine, aviation and transit 33,927 (14,458) (50,558) (31,089) Construction defect 27,476 (6,092) (13,382) 8,002 Professional indemnity/ Directors & Officers 63,878 3,698 (79,181) (11,605) Motor 349,366 (106,561) (95,040) 147,765 Property 71,422 (24,356) (64,331) (17,265) All Other 48,831 (54,604) 23,110 17,337 Total $ 1,064,911 $ (449,610) $ (742,417) $ (127,116) The following table shows the components of the 2019 reduction in estimates of net ultimate losses related to prior periods by line of business for the Non-life Run-off segment. 2019 Net losses paid Net change in case and LAE reserves Net change in IBNR reserves Increase (reduction) in estimates of net ultimate losses Asbestos $ 118,557 $ 35,003 $ (146,749) $ 6,811 Environmental 16,899 13,796 (15,707) 14,988 General Casualty 175,044 (89,968) (91,818) (6,742) Workers' Compensation 208,961 (156,435) (188,944) (136,418) Marine, aviation and transit 82,058 (77,958) (24,508) (20,408) Construction defect 32,078 (8,313) (25,025) (1,260) Professional indemnity/ Directors & Officers 103,413 (36,986) (104,984) (38,557) Motor 276,563 (134,127) (179,887) (37,451) Property 94,093 (73,259) (7,358) 13,476 All Other 75,138 (25,749) (62,913) (13,524) Total $ 1,182,804 $ (553,996) $ (847,893) $ (219,085) The following table shows the components of the 2018 reduction in estimates of net ultimate losses related to prior periods by line of business for the Non-life Run-off segment. 2018 Net losses paid Net change in case and LAE reserves Net change in IBNR reserves Increase (reduction) in estimates of net ultimate losses Asbestos $ 108,248 $ (21,535) $ (151,662) $ (64,949) Environmental 21,273 479 (7,599) 14,153 General Casualty 141,624 (115,240) (60,828) (34,444) Workers' Compensation 139,226 (178,138) (115,648) (154,560) Marine, aviation and transit 67,831 (44,200) (21,188) 2,443 Construction defect 22,182 (7,257) (33,146) (18,221) Professional indemnity/ Directors & Officers 161,797 (11,159) (130,957) 19,681 Motor 104,182 (109,962) (34,215) (39,995) Property 22,178 (24,271) (11,497) (13,590) All Other 50,271 (40,841) (6,387) 3,043 Total $ 838,812 $ (552,124) $ (573,127) $ (286,439) The following tables provide a breakdown of gross and net losses and LAE reserves, consisting of Outstanding Loss Reserve ("OLR") and IBNR by line of business and adjustments for fair value resulting from business combinations, adjustments for where we elected the fair value option, deferred charge assets and ULAE, as of December 31, 2020 and 2019: 2020 Gross Net OLR IBNR Total OLR IBNR Total (in thousands of U.S. dollars) Asbestos $ 544,438 $ 1,234,101 $ 1,778,539 $ 464,102 $ 1,122,021 $ 1,586,123 Environmental 184,783 118,111 302,894 164,709 100,339 265,048 General casualty 610,437 1,279,991 1,890,428 492,039 1,247,662 1,739,701 Workers' compensation/personal accident 1,087,324 918,238 2,005,562 912,068 776,941 1,689,009 Marine, aviation and transit 271,469 73,081 344,550 229,464 56,414 285,878 Construction defect 23,380 85,578 108,958 23,109 83,039 106,148 Professional indemnity/Directors & Officers 764,768 336,705 1,101,473 526,333 307,349 833,682 Motor 619,682 355,044 974,726 451,097 283,576 734,673 Property 116,398 35,832 152,230 97,826 34,182 132,008 Other 217,746 204,819 422,565 141,448 121,895 263,343 $ 4,440,425 $ 4,641,500 $ 9,081,925 $ 3,502,195 $ 4,133,418 $ 7,635,613 Fair value adjustments (142,854) (128,841) Fair value adjustments - fair value option (54,589) (33,163) Net deferred charge assets and gains on retroactive reinsurance — (218,722) ULAE 350,600 333,913 Total $ 9,235,082 $ 7,588,800 2019 Gross Net OLR IBNR Total OLR IBNR Total (in thousands of U.S. dollars) Asbestos $ 542,681 $ 1,373,678 $ 1,916,359 $ 490,117 $ 1,271,982 $ 1,762,099 Environmental 187,165 156,121 343,286 173,878 142,351 316,229 General casualty 501,863 489,129 990,992 399,396 421,426 820,822 Workers' compensation/personal accident 1,270,530 977,808 2,248,338 963,578 751,074 1,714,652 Marine, aviation and transit 290,067 121,577 411,644 244,611 100,135 344,746 Construction defect 29,772 98,312 128,084 29,245 94,888 124,133 Professional indemnity/Directors & Officers 693,760 265,490 959,250 485,478 170,926 656,404 Motor 480,668 233,806 714,474 317,829 165,543 483,372 Property 140,620 63,604 204,224 122,010 56,450 178,460 Other 269,956 165,882 435,838 208,647 97,573 306,220 $ 4,407,082 $ 3,945,407 $ 8,352,489 $ 3,434,789 $ 3,272,348 $ 6,707,137 Fair value adjustments (170,689) (157,036) Fair value adjustments - fair value option (217,933) (129,848) Net deferred charge assets and gain liabilities on retroactive reinsurance — (259,587) ULAE 331,494 331,494 Total $ 8,295,361 $ 6,492,160 The following table provides a breakdown of the gross and net losses and LAE reserves by line of business and the fair value adjustments recorded on the acquired gross and net losses and LAE reserves and ULAE as of December 31, 2019 for the Atrium segment. The breakdown as of December 31, 2020 has not been disclosed below since we have classified the Atrium segment as held-for-sale as discussed in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations." 2019 Gross Net OLR IBNR Total OLR IBNR Total (in thousands of U.S. dollars) Marine, Aviation and Transit $ 24,668 $ 34,156 $ 58,824 $ 21,012 $ 24,829 $ 45,841 Binding Authorities 31,507 54,039 85,546 29,590 51,984 81,574 Reinsurance 18,385 29,533 47,918 16,209 23,338 39,547 Accident and Health 5,460 7,880 13,340 4,735 7,469 12,204 Non-Marine Direct and Facultative 9,121 10,935 20,056 8,584 9,637 18,221 Total $ 89,141 $ 136,543 $ 225,684 $ 80,130 $ 117,257 $ 197,387 Fair value adjustments 3,700 3,181 ULAE 2,288 2,288 Total $ 231,672 $ 202,856 The following tables provide a breakdown of the gross and net losses and LAE reserves by line of business and the fair value adjustments recorded on the acquired gross and net losses and LAE reserves and ULAE as of December 31, 2020 and 2019: 2020 Gross Net OLR IBNR Total OLR IBNR Total (in thousands of U.S. dollars) Casualty $ 115,295 $ 276,941 $ 392,236 $ 98,721 $ 232,433 $ 331,154 Marine 142,631 174,015 316,646 119,628 132,482 252,110 Property 322,735 117,240 439,975 141,089 81,459 222,548 Aerospace 84,515 36,178 120,693 42,100 18,240 60,340 Workers' Compensation 12,044 11,589 23,633 12,044 11,589 23,633 Total $ 677,220 $ 615,963 $ 1,293,183 $ 413,582 $ 476,203 $ 889,785 Fair value adjustments (329) 1,010 ULAE 35,102 35,101 Total $ 1,327,956 $ 925,896 2019 Gross Net OLR IBNR Total OLR IBNR Total (in thousands of U.S. dollars) Casualty $ 121,945 $ 210,969 $ 332,914 $ 108,543 $ 204,800 $ 313,343 Marine 189,355 161,379 350,734 158,252 128,242 286,494 Property 341,677 131,596 473,273 150,559 87,653 238,212 Aerospace 75,764 32,325 108,089 47,256 22,389 69,645 Workers' Compensation 15,089 19,865 34,954 15,089 19,865 34,954 Total $ 743,830 $ 556,134 $ 1,299,964 $ 479,699 $ 462,949 $ 942,648 Fair value adjustments (522) 1,600 ULAE 18,852 18,852 Total $ 1,318,294 $ 963,100
Incurred and Paid Loss Development Information, and IBNR Liabilities and Cumulative Loss Frequency	The following table provides a summary of our net loss reserves, prior to provisions for bad debt, fair value adjustments, deferred charge assets and deferred gain liabilities and ULAE as of December 31, 2020, by year of acquisition and by significant line of business: Acquisition Year 2010 and Prior 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 Total Asbestos $ 142,028 $ — $ — $ 7,767 $ — $ — $ 407,958 $ 726,901 $ 1,105 $ 277,947 $ — $ 1,563,706 Environmental 42,356 — — — — — 89,865 22,891 11,203 95,072 — 261,387 General casualty 52,582 13,270 9,983 16,696 31,610 34,704 3,727 44,551 228,419 218,995 1,077,908 1,732,445 Workers' compensation/personal accident 42,908 125,649 — 48,207 — 287,653 219,157 53,659 322,737 387,438 199,864 1,687,272 Marine, aviation and transit 8,760 2,747 — (188) 10,592 1,616 32 77,321 106,431 56,709 19,848 283,868 Construction defect 43 — — — — 36,258 14,289 18,836 — 36,709 — 106,135 Professional indemnity/Directors & Officers 7,539 9,564 23,210 — 20,942 — 76,314 — 331,676 130,906 232,934 833,085 Motor 12,452 201 276 — 1,465 13,147 — 3,710 260,797 17,899 422,321 732,268 Property 3,301 161 7,008 — 18,165 3,880 465 (114) 47,270 39,286 10,887 130,309 All Other 17,473 854 2,696 4,260 9,676 6,959 23,582 94,499 18,222 78,474 — 256,695 Total $ 329,442 $ 152,446 $ 43,173 $ 76,742 $ 92,450 $ 384,217 $ 835,389 $ 1,042,254 $ 1,327,860 $ 1,339,435 $ 1,963,762 $ 7,587,170 Business Acquired and Contracts Incepting in the Year Ended December 31, 2011 Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Years Ended December 31, Accident Year Total Net Reserves Acquired 2011 (unaudited) 2012 (unaudited) 2013 (unaudited) 2014 (unaudited) 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 597,263 $ 621,819 $ 589,004 $ 489,877 $ 426,777 $ 375,227 $ 319,423 $ 274,136 $ 261,234 $ 240,808 $ 229,458 $ 17,493 112,837 2011 — 102 36 45 54 61 71 79 86 93 100 — 19 2012 — 122 11 10 10 10 17 18 17 17 — 7 2013 — 23 43 15 15 15 15 15 15 — 16 2014 — 1 3 3 3 18 15 14 2 14 2015 — — (2) (2) 32 24 19 — 1 2016 — 2 (139) (111) (99) (88) 7 2 2017 — — 21 15 17 1 2 2018 — 7 8 8 1 1 2019 — — 2 1 1 2020 — 2 1 1 $ 597,263 $ 229,564 $ 17,506 112,901 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For The Years Ended December 31, Accident Year 2011 (unaudited) 2012 (unaudited) 2013 (unaudited) 2014 (unaudited) 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 2010 and Prior $ 58,934 $ 98,969 $ 90,711 $ 24,238 $ 19,370 $ 27,563 $ 19,697 $ 31,108 $ 56,741 $ 77,051 2011 27 36 46 54 61 71 79 86 93 100 2012 6 10 10 10 10 17 17 17 17 2013 6 11 15 15 15 15 15 15 2014 1 3 3 3 4 7 7 2015 (1) (2) (2) 2 11 18 2016 2 (153) (125) (114) (105) 2017 — 3 6 10 2018 1 4 5 2019 — — 2020 — $ 77,118 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 152,446 Business Acquired and Contracts Incepting in the Year Ended December 31, 2012 Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Years Ended December 31, Accident Year Total Net Reserves Acquired 2012 (unaudited) 2013 (unaudited) 2014 (unaudited) 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 326,229 $ 328,419 $ 321,295 $ 312,510 $ 297,081 $ 286,660 $ 277,778 $ 269,004 $ 263,472 $ 252,318 $ 10,889 47,773 2011 1,487 1,466 1,336 1,182 1,095 1,072 1,049 1,032 1,032 1,032 — 5 2012 55 81 49 363 344 406 397 167 167 167 — 6 2013 — 946 119 427 433 421 136 136 136 — 5 2014 (60) 2,991 3,108 1,552 1,300 1,195 1,146 1,068 1 7 2015 — 729 1,517 739 739 739 739 — 5 2016 (485) 67 1,266 1,113 1,059 445 37 2 2017 — 75 167 100 100 — 4 2018 (59) — 154 74 4 1 2019 (123) 274 145 11 4 2020 — 164 — 3 $ 327,044 $ 256,388 $ 10,942 47,815 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For The Years Ended December 31, Accident Year 2012 (unaudited) 2013 (unaudited) 2014 (unaudited) 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 2010 and Prior $ 3,194 $ 70,440 $ 112,966 $ 144,553 $ 169,781 $ 180,270 $ 194,011 $ 204,482 $ 209,656 2011 120 496 742 866 928 990 1,032 1,032 1,032 2012 31 49 49 52 167 167 167 167 167 2013 109 119 136 136 136 136 136 136 2014 67 224 459 675 864 989 1,053 2015 112 117 739 739 739 739 2016 3 56 98 98 98 2017 13 43 100 100 2018 — 30 34 2019 18 36 2020 164 $ 213,215 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 43,173 Business Acquired and Contracts Incepting in the Year Ended December 31, 2013 Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Years Ended December 31, Accident Year Total Net Reserves Acquired 2013 (unaudited) 2014 (unaudited) 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 320,974 $ 349,297 $ 354,585 $ 361,812 $ 356,522 $ 340,248 $ 326,851 $ 313,347 $ 314,497 $ 16,353 56,441 2011 96,929 102,288 100,482 100,243 95,848 87,913 86,403 85,919 81,616 2,700 11,185 2012 131,119 127,323 121,364 118,085 114,772 110,045 107,853 108,025 105,564 1,831 10,423 2013 13,062 90,739 91,634 88,920 85,791 81,732 80,036 80,091 79,174 1,073 5,656 2014 — 4,514 3,714 3,425 16,800 16,225 16,304 16,269 55 174 2015 — 265 280 982 329 250 237 42 2 2016 — 103 71 70 69 69 1 1 2017 — 30 13 13 13 — 1 2018 — 22 17 18 — 1 2019 — 13 15 — 1 2020 — 61 4 1 $ 562,084 $ 597,533 $ 22,059 83,886 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For The Years Ended December 31, Accident Year 2013 (unaudited) 2014 (unaudited) 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 2010 and Prior $ 74,418 $ 134,409 $ 186,762 $ 222,891 $ 229,942 $ 243,755 $ 249,023 $ 258,436 2011 30,323 52,455 63,952 70,498 75,055 77,290 79,112 73,282 2012 33,361 59,095 74,663 86,916 92,445 96,780 99,781 98,096 2013 17,022 37,653 52,638 62,876 68,866 71,487 74,556 74,472 2014 993 1,747 2,256 15,804 15,959 16,123 16,164 2015 43 102 112 165 190 191 2016 34 64 65 66 67 2017 9 13 13 13 2018 13 17 18 2019 8 15 2020 37 $ 520,791 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 76,742 Business Acquired and Contracts Incepting in the Year Ended December 31, 2014 Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Years Ended December 31, Accident Year Total Net Reserves Acquired 2014 (unaudited) 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 142,341 $ 133,678 $ 123,973 $ 155,274 $ 142,256 $ 141,058 $ 145,889 $ 144,874 $ 6,454 12,014 2011 74,248 129,149 154,394 134,137 136,257 137,806 139,997 135,181 10,057 6,228 2012 141,597 147,347 178,577 187,062 179,745 165,821 162,740 160,769 10,449 6,393 2013 86,920 76,313 95,125 83,564 88,189 90,387 88,391 90,951 8,947 3,173 2014 — 13,802 9,554 14,506 7,438 6,590 6,954 7,098 1,708 1,112 2015 — 33,549 15,553 20,741 18,929 17,206 17,090 72 183 2016 — 330 1,108 4,594 771 724 89 45 2017 — 5,078 3,893 8,200 8,463 24 37 2018 — 6 5 82 — 19 2019 — — — — 10 2020 — — — 6 $ 445,106 $ 565,232 $ 37,800 29,220 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For The Years Ended December 31, Accident Year 2014 (unaudited) 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 2010 and Prior $ 36,509 $ 82,699 $ 103,197 $ 118,857 $ 120,309 $ 121,847 $ 127,622 2011 84,031 109,675 110,575 113,701 120,155 123,335 123,364 2012 47,495 90,307 120,910 130,001 130,105 133,900 133,026 2013 21,752 40,817 48,223 56,941 65,073 65,625 66,225 2014 1,462 2,504 3,293 3,989 6,147 6,660 6,654 2015 1,741 4,308 11,566 13,371 13,417 13,473 2016 20 556 558 561 559 2017 537 1,541 1,238 1,778 2018 5 5 81 2019 — — 2020 — $ 472,782 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 92,450 Business Acquired and Contracts Incepting in the Year Ended December 31, 2015 Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Years Ended December 31, Accident Year Total Net Reserves Acquired 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 1,003,949 $ 933,328 $ 640,324 $ 594,466 $ 564,502 $ 521,598 $ 505,379 $ 49,461 13,557 2011 124,727 137,429 131,303 129,657 128,155 128,672 126,764 14,306 5,587 2012 179,136 187,488 197,895 201,017 194,277 193,553 192,426 18,110 4,885 2013 229,590 189,838 196,582 199,983 189,737 185,101 184,590 13,855 4,699 2014 144,392 143,193 137,668 142,937 137,541 152,478 147,567 7,413 7,783 2015 23,750 70,276 69,322 66,152 64,974 69,465 73,256 6,959 10,997 2016 — 14,872 13,141 13,440 14,576 12,868 2,178 14,283 2017 — 4,095 4,527 5,277 6,860 345 3,534 2018 — 3,055 1,889 1,805 985 400 2019 — 1,838 1,873 1,831 51 2020 — 1,951 1,962 3 $ 1,705,544 $ 1,255,339 $ 117,405 65,779 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For The Years Ended December 31, Accident Year 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 2010 and Prior $ 32,819 $ 83,350 $ 134,737 $ 166,983 $ 195,205 $ 220,984 2011 33,827 55,115 71,023 86,397 98,000 105,178 2012 52,728 94,831 119,520 142,358 158,620 168,213 2013 46,761 89,930 120,509 145,788 159,767 164,215 2014 30,747 64,475 91,016 109,451 125,619 133,094 2015 20,653 38,709 46,668 51,994 59,963 63,181 2016 5,603 7,371 8,687 9,861 10,321 2017 2,321 3,925 4,767 5,047 2018 567 862 820 2019 45 65 2020 4 $ 871,122 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 384,217 Business Acquired and Contracts Incepting in the Year Ended December 31, 2015 - Workers' Compensation Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Years Ended December 31, Accident Year Total Net Reserves Acquired 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 953,178 $ 868,509 $ 569,692 $ 518,764 $ 490,534 $ 449,380 $ 434,422 $ 40,504 8,605 2011 76,789 73,723 69,009 68,013 66,781 67,741 65,825 3,685 1,241 2012 120,298 110,007 108,251 106,625 100,187 99,212 98,733 4,613 1,809 2013 146,237 124,726 122,238 121,010 113,056 112,677 113,414 5,595 2,386 2014 82,141 86,852 82,038 83,095 78,389 78,948 80,307 1,513 3,686 2015 4,089 18,647 12,623 13,488 12,295 11,309 11,337 557 2,900 2016 — 873 955 583 536 514 52 38 2017 — 358 61 41 33 13 10 2018 — — 5 3 — 1 2019 — 1 3 1 1 2020 — — — — $ 1,382,732 $ 804,591 $ 56,533 20,677 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For The Years Ended December 31, Accident Year 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 2010 and Prior $ 20,630 $ 65,008 $ 107,906 $ 132,025 $ 155,329 $ 177,205 2011 16,032 30,462 39,635 50,470 55,595 58,420 2012 25,103 52,851 66,092 79,367 88,369 91,332 2013 27,737 55,675 75,065 91,559 100,890 104,265 2014 17,824 38,051 53,308 65,561 72,696 75,781 2015 3,034 5,672 7,917 9,169 9,248 9,461 2016 134 363 417 447 452 2017 2 10 18 19 2018 — 1 2 2019 — 1 2020 — $ 516,938 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 287,653 Business Acquired and Contracts Incepting in the Year Ended December 31, 2016 Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Years Ended December 31, Accident Year Total Net Reserves Acquired 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 1,304,938 $ 1,316,544 $ 1,346,575 $ 1,321,289 $ 1,322,161 $ 1,361,353 $ 305,042 24,449 2011 17,291 17,291 19,920 19,754 18,829 18,609 2,266 861 2012 13,717 13,717 17,020 14,765 12,717 13,037 1,829 809 2013 373 373 1,312 1,237 1,120 914 603 127 2014 391 391 1,380 1,056 869 817 310 57 2015 — — — — — — — — 2016 — — — — — — — — 2017 — — — — — — — 2018 — — — — — — 2019 — — — — — 2020 — — — — $ 1,336,710 $ 1,394,730 $ 310,050 26,303 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Accident Year 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 2010 and Prior $ 101,098 $ 222,703 $ 331,218 $ 445,770 $ 536,987 2011 2,758 6,647 8,218 9,691 13,098 2012 2,734 5,206 6,461 7,587 8,492 2013 145 191 278 285 301 2014 178 207 284 366 463 2015 — — — — — 2016 — — — — — 2017 — — — — 2018 — — — 2019 — — 2020 — $ 559,341 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 835,389 Business Acquired and Contracts Incepting in the Year Ended December 31, 2016 - Workers' Compensation Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Years Ended December 31, Accident Year Total Net Reserves Acquired 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 437,457 $ 437,805 $ 403,319 $ 391,476 $ 382,446 $ 367,109 $ 19,015 9,452 2011 15,376 15,376 16,399 16,501 16,327 16,472 1,374 469 2012 13,074 13,074 15,465 13,276 11,379 11,256 1,020 612 2013 — — — — — — — — 2014 — — — — — — — — 2015 — — — — — — — — 2016 — — — — — — — — 2017 — — — — — — — 2018 — — — — — — 2019 — — — — — 2020 — — — — $ 465,907 $ 394,837 $ 21,409 10,533 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Accident Year 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 2010 and Prior $ 35,518 $ 65,264 $ 90,599 $ 127,081 $ 155,433 2011 2,631 5,871 7,305 8,756 12,130 2012 2,638 5,028 6,247 7,382 8,117 2013 — — — — — 2014 — — — — — 2015 — — — — — 2016 — — — — — 2017 — — — — 2018 — — — 2019 — — 2020 — $ 175,680 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 219,157 Business Acquired and Contracts Incepting in the Year Ended December 31, 2017 Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Years Ended December 31, Accident Year Total Net Reserves Acquired 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 1,507,609 $ 1,433,301 $ 1,351,451 $ 1,364,113 $ 1,349,226 $ 749,197 31,566 2011 40,743 29,274 25,389 27,316 26,942 5,834 8 2012 43,653 35,470 31,238 29,456 28,485 3,744 10 2013 35,671 30,338 28,139 24,707 29,829 1,860 11 2014 32,858 20,315 16,984 15,996 16,342 2,287 20 2015 8,808 6,494 7,002 6,295 6,043 234 8 2016 362 (4) 126 919 1,074 394 3 2017 — 174 — — — — 1 2018 — — — — — — 2019 — — — — — 2020 — — — — $ 1,669,704 $ 1,457,941 $ 763,550 31,627 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Accident Year 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 2010 and Prior $ 85,514 $ 175,630 $ 257,071 $ 334,586 2011 4,125 9,257 12,971 15,407 2012 10,348 15,372 18,605 21,076 2013 9,509 15,714 21,280 25,832 2014 6,482 8,986 11,559 12,668 2015 1,361 3,720 4,687 5,582 2016 (56) 66 434 536 2017 4 — — — 2018 — — — 2019 — — 2020 — $ 415,687 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 1,042,254 Business Acquired and Contracts Incepting in the Year Ended December 31, 2018 Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Year Ended December 31, Accident Year Total Net Reserves Acquired 2018 (unaudited) 2019 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 662,009 $ 497,101 $ 476,164 $ 409,505 $ 50,970 223,572 2011 164,556 150,408 150,388 147,796 16,240 14,072 2012 232,116 224,955 224,959 225,528 29,903 14,382 2013 272,732 274,377 268,237 250,013 35,175 16,126 2014 419,593 462,858 439,396 415,829 38,688 19,463 2015 365,429 483,489 480,093 496,187 62,476 24,768 2016 173,309 175,428 178,061 169,872 36,090 2,026 2017 207,040 207,190 205,466 204,490 55,056 4,163 2018 315,659 315,659 285,038 282,279 53,287 4,929 2019 — 68,271 68,041 9,762 1,634 2020 — — — — $ 2,812,443 $ 2,669,540 $ 387,647 325,135 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Year Ended December 31, Accident Year 2018 (unaudited) 2019 2020 2010 and Prior $ 50,515 $ 86,132 $ 81,554 2011 26,236 53,151 65,522 2012 31,772 81,356 106,297 2013 41,544 96,968 133,398 2014 90,689 188,721 235,787 2015 95,688 199,373 269,559 2016 6,854 63,982 93,705 2017 56 72,800 113,770 2018 — 139,815 191,442 2019 39,099 50,646 2020 — $ 1,341,680 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 1,327,860 Business Acquired and Contracts Incepting in the Year Ended December 31, 2018 - General Casualty Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Year Ended December 31, Accident Year Total Net Reserves Acquired 2018 (unaudited) 2019 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 130,049 $ 74,102 $ 70,937 $ 67,933 $ 4,827 47,893 2011 18,044 16,554 16,650 15,855 151 1,421 2012 37,454 33,433 29,123 29,760 3,270 1,593 2013 43,301 56,092 46,596 46,999 4,352 1,596 2014 66,562 80,896 74,947 68,535 5,802 2,291 2015 79,191 94,124 104,790 109,694 14,188 3,594 2016 28,825 28,825 36,585 36,684 10,075 253 2017 37,209 37,209 41,664 43,174 14,554 230 2018 39,888 39,888 40,753 39,157 11,605 182 2019 — 6,767 6,187 394 34 2020 — — — — $ 480,523 $ 463,978 $ 69,218 59,087 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Year Ended December 31, Accident Year 2018 (unaudited) 2019 2020 2010 and Prior $ 9,164 $ 18,817 $ 29,840 2011 2,349 7,115 11,018 2012 1,281 11,453 14,383 2013 10,404 19,938 27,717 2014 13,766 27,833 41,899 2015 15,494 31,535 49,860 2016 — 14,109 18,916 2017 — 11,048 21,130 2018 — 8,879 17,455 2019 2,373 3,341 2020 — $ 235,559 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 228,419 Business Acquired and Contracts Incepting in the Year Ended December 31, 2018 - Workers' Compensation Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Year Ended December 31, Accident Year Total Net Reserves Acquired 2018 (unaudited) 2019 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 131,873 $ 122,831 $ 129,280 $ 131,775 $ 39,843 2,098 2011 29,897 28,685 29,981 27,203 9,067 401 2012 28,749 29,181 27,676 26,833 10,597 468 2013 38,029 38,554 38,093 35,212 13,243 869 2014 65,049 66,346 57,163 52,797 17,605 1,345 2015 38,851 39,379 35,235 33,253 13,026 1,464 2016 44,686 44,686 38,945 37,714 15,857 892 2017 52,360 52,360 49,156 45,529 23,004 998 2018 65,075 65,075 60,923 59,768 19,310 886 2019 — 20,889 21,417 4,445 383 2020 — — — — $ 494,569 $ 471,501 $ 165,997 9,804 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Year Ended December 31, Accident Year 2018 (unaudited) 2019 2020 2010 and Prior $ 604 $ 11,788 $ 21,726 2011 2,281 5,592 9,418 2012 516 5,508 7,941 2013 1,525 7,773 12,280 2014 3,260 14,687 21,380 2015 1,403 4,355 9,844 2016 — 3,666 7,176 2017 — 5,900 9,088 2018 — 28,725 34,317 2019 13,483 15,594 2020 — $ 148,764 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 322,737 Business Acquired and Contracts Incepting in the Year Ended December 31, 2018 - Motor Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Year Ended December 31, Accident Year Total Net Reserves Acquired 2018 (unaudited) 2019 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 43,818 $ 31,489 $ 30,036 $ 33,230 $ 2,599 1,323 2011 48,231 38,092 37,707 36,301 2,031 1,239 2012 65,427 58,006 63,786 59,276 5,862 1,641 2013 78,456 71,276 65,012 55,345 5,744 683 2014 116,677 103,761 90,902 84,459 5,243 1,260 2015 135,855 133,493 132,167 132,165 15,246 1,510 2016 93,164 95,283 97,040 91,600 9,824 732 2017 100,321 100,471 99,135 102,038 16,628 2,797 2018 180,471 180,471 157,556 160,143 21,609 3,731 2019 — 39,757 39,647 4,955 1,200 2020 — — — — $ 862,420 $ 794,204 $ 89,741 16,116 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Year Ended December 31, Accident Year 2018 (unaudited) 2019 2020 2010 and Prior $ 7,460 $ 13,722 $ 16,655 2011 6,060 12,980 15,464 2012 12,380 24,433 31,136 2013 11,114 29,311 35,186 2014 22,393 49,089 60,254 2015 21,712 61,928 84,976 2016 6,854 43,851 65,287 2017 56 48,661 73,440 2018 — 86,861 120,041 2019 22,687 30,968 2020 — $ 533,407 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 260,797 Business Acquired and Contracts Incepting in the Year Ended December 31, 2018 - Professional Indemnity/Directors & Officers Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Year Ended December 31, Accident Year Total Net Reserves Acquired 2018 (unaudited) 2019 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 236,568 $ 137,394 $ 147,383 $ 143,585 $ (3,639) 56,674 2011 46,512 52,553 48,884 51,600 3,185 3,762 2012 57,937 70,636 69,641 74,884 4,399 3,285 2013 59,457 63,284 78,933 76,291 10,543 3,257 2014 88,173 111,193 107,411 114,621 11,523 3,619 2015 47,337 100,975 81,272 85,394 15,074 3,990 2016 — — — — — — 2017 — — — — — — 2018 — — — — — — 2019 — — — — — 2020 — — — — $ 535,984 $ 546,375 $ 41,085 74,587 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Year Ended December 31, Accident Year 2018 (unaudited) 2019 2020 2010 and Prior $ 29,359 $ 54,157 $ 28,528 2011 13,123 20,017 22,250 2012 16,382 23,237 33,794 2013 10,987 21,919 34,269 2014 22,734 39,601 61,024 2015 14,245 26,595 34,834 2016 — — — 2017 — — — 2018 — — — 2019 — — 2020 — $ 214,699 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 331,676 Business Acquired and Contracts Incepting in the Year Ended December 31, 2019 Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Year Ended December 31, Accident Year Total Net Reserves Acquired 2019 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 652,608 $ 630,171 $ 628,495 $ 272,910 74,742 2011 49,873 40,554 35,876 8,773 15,218 2012 73,098 54,301 49,349 12,905 12,329 2013 112,031 93,213 88,066 29,931 14,952 2014 137,324 137,478 127,704 53,814 17,624 2015 179,651 188,833 196,007 80,816 25,081 2016 253,099 295,011 260,473 118,653 32,057 2017 116,386 116,386 116,386 116,386 2 2018 162,744 162,744 162,744 162,744 2 2019 — 54,571 64,595 6,155 1,679 2020 — 27,975 5,483 1,020 $ 1,736,814 $ 1,757,670 $ 868,570 194,706 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Year Ended December 31, Accident Year 2019 2020 2010 and Prior $ 26,817 $ 106,195 2011 4,786 8,100 2012 6,886 9,565 2013 13,540 20,906 2014 28,188 47,310 2015 33,417 63,994 2016 56,125 84,592 2017 — — 2018 — — 2019 25,595 55,912 2020 21,661 $ 418,235 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 1,339,435 Business Acquired and Contracts Incepting in the Year Ended December 31, 2019 - General Casualty Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Year Ended December 31, Accident Year Total Net Reserves Acquired 2019 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 12,765 $ 9,788 $ 9,994 $ 1,620 1,424 2011 12,321 9,490 7,979 3,587 796 2012 18,107 14,471 13,786 8,214 1,165 2013 23,750 18,230 20,960 8,897 313 2014 33,767 31,181 29,341 16,377 905 2015 58,818 45,936 41,158 18,055 2,003 2016 48,606 64,159 58,061 32,692 3,134 2017 32,188 32,188 32,188 32,188 1 2018 45,010 45,010 45,010 45,010 1 2019 — 1,750 1,873 510 225 2020 — 1,118 267 411 $ 285,332 $ 261,468 $ 167,417 10,378 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Year Ended December 31, Accident Year 2019 2020 2010 and Prior $ 2,230 $ 2,894 2011 810 1,869 2012 3,326 6,604 2013 3,499 5,813 2014 3,878 8,155 2015 4,421 5,121 2016 4,894 10,723 2017 — — 2018 — — 2019 — 841 2020 453 $ 42,473 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 218,995 Business Acquired and Contracts Incepting in the Year Ended December 31, 2019 - Workers' Compensation Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Year Ended December 31, Accident Year Total Net Reserves Acquired 2019 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 5,860 $ 4,420 $ 4,551 $ 1,938 9,869 2011 2,474 2,410 2,409 2,342 1,082 2012 6,280 6,176 6,176 6,991 1,640 2013 16,738 18,339 15,980 14,415 2,897 2014 35,023 35,426 35,556 31,501 3,410 2015 57,194 56,171 57,314 48,840 4,802 2016 87,702 85,530 84,862 70,769 4,829 2017 84,197 84,197 84,197 84,197 1 2018 117,734 117,734 117,734 117,734 1 2019 — — — — — 2020 — 2,045 — 189 $ 413,202 $ 410,824 $ 378,727 28,720 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Year Ended December 31, Accident Year 2019 2020 2010 and Prior $ 607 $ 696 2011 22 23 2012 22 63 2013 458 572 2014 3,080 3,443 2015 3,549 6,325 2016 7,337 12,137 2017 — — 2018 — — 2019 — — 2020 127 $ 23,386 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 387,438 Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Years Ended December 31, Accident Year Total Net Reserves Acquired 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 256,228 $ 169,601 $ 91,688 47 2011 26,488 26,983 25,162 36 2012 58,128 58,241 53,749 74 2013 68,683 63,922 47,944 140 2014 100,054 102,600 83,249 201 2015 161,383 161,352 113,476 384 2016 210,661 205,305 120,481 816 2017 316,751 342,330 168,832 1,770 2018 432,590 575,706 305,471 3,108 2019 344,495 343,168 301,463 1,351 2020 166,946 168,091 144,090 1,481 $ 2,142,407 $ 2,217,299 $ 1,455,605 9,408 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Accident Year 2020 2010 and Prior $ 2,310 2011 54 2012 601 2013 4,283 2014 5,975 2015 12,253 2016 33,985 2017 73,001 2018 111,871 2019 1,509 2020 7,695 253,537 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 1,963,762 Business Acquired and Contracts Incepting in the Year Ended December 31, 2020 - General Casualty Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Years Ended December 31, Accident Year Total Net Reserves Acquired 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 43,511 $ 43,849 $ 36,455 36 2011 26,434 26,928 25,133 29 2012 55,478 55,591 51,130 60 2013 60,872 56,111 41,186 122 2014 87,620 90,182 71,022 185 2015 140,583 139,947 96,032 280 2016 142,395 143,156 100,293 394 2017 142,862 137,097 112,135 439 2018 141,803 138,267 133,942 316 2019 202,521 201,174 179,284 388 2020 83,021 82,598 77,737 338 $ 1,127,100 $ 1,114,900 $ 924,349 2,587 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Accident Year 2020 2010 and Prior $ 522 2011 54 2012 601 2013 3,258 2014 5,983 2015 10,230 2016 9,125 2017 4,149 2018 400 2019 203 2020 2,467 36,992 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 1,077,908 Business Acquired and Contracts Incepting in the Year Ended December 31, 2020 - Motor Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Years Ended December 31, Accident Year Total Net Reserves Acquired 2020 IBNR Cumulative Number of Claims 2010 and Prior $ — $ — $ — — 2011 — — — — 2012 — — — — 2013 — — — — 2014 — — — — 2015 2,397 3,018 603 19 2016 48,505 42,420 2,779 221 2017 154,070 185,445 38,279 1,099 2018 250,028 397,413 145,623 2,204 2019 — — — — 2020 — — — — $ 455,000 $ 628,296 $ 187,284 3,543 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Accident Year 2020 2010 and Prior $ — 2011 — 2012 — 2013 — 2014 — 2015 2,012 2016 24,804 2017 68,712 2018 110,447 2019 — 2020 — 205,975 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 422,321 Business Acquired and Contracts Incepting in the Year Ended December 31, 2020 - Professional Indemnity/Directors & Officers Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For the Years Ended December 31, Accident Year Total Net Reserves Acquired 2020 IBNR Cumulative Number of Claims 2010 and Prior $ 4,680 $ 4,678 $ 4,679 1 2011 44 44 44 3 2012 2,593 2,593 2,584 4 2013 7,791 7,791 6,745 6 2014 11,949 11,949 11,947 4 2015 16,120 16,120 15,769 4 2016 16,259 16,216 16,053 9 2017 17,212 17,206 16,906 41 2018 25,323 25,290 19,209 115 2019 99,460 99,350 92,944 135 2020 34,548 34,757 30,144 79 $ 235,979 $ 235,994 $ 217,024 401 Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For the Years Ended December 31, Accident Year 2020 2010 and Prior $ — 2011 — 2012 — 2013 1,025 2014 — 2015 6 2016 1 2017 5 2018 475 2019 410 2020 1,138 3,060 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 232,934 Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For The Years Ended December 31, Accident Year 2014 (unaudited) 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 IBNR (1) Cumulative Number of Claims 2010 and Prior $ 100,449 $ 101,217 $ 101,444 $ 101,801 $ 102,539 $ 102,317 $ 102,661 $ 19 4,322 2011 16,244 18,740 19,681 19,103 27,703 27,859 28,027 429 2,962 2012 39,797 33,853 30,788 28,482 33,511 36,159 37,072 3,418 3,521 2013 51,458 47,304 54,282 53,493 56,145 63,323 67,638 9,044 4,821 2014 66,094 67,141 67,461 66,559 66,585 75,513 72,097 10,495 4,863 2015 76,470 82,050 81,685 92,904 99,425 101,191 13,037 4,323 2016 92,406 95,726 111,020 135,670 128,139 25,293 3,825 2017 100,585 135,743 161,288 166,472 34,822 3,899 2018 87,781 101,381 106,014 39,329 2,929 2019 42,595 59,902 23,758 2,581 2020 98,738 72,789 1,582 Total $ 967,951 $ 232,433 39,628 (1) Total of IBNR plus expected development on reported losses. Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance For The Years Ended December 31, Accident Year 2014 (unaudited) 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 2010 and Prior $ 99,643 $ 101,181 $ 101,326 $ 101,712 $ 101,783 $ 101,813 $ 101,886 2011 12,394 15,941 18,354 18,760 27,385 27,401 27,426 2012 13,336 20,634 22,746 23,711 32,644 32,666 32,706 2013 16,373 22,131 35,799 38,866 42,123 48,898 52,333 2014 4,318 16,141 27,043 36,802 46,654 49,571 51,949 2015 6,439 21,503 36,971 50,598 69,948 75,875 2016 4,206 32,864 59,074 76,175 92,223 2017 7,712 41,896 87,902 114,062 2018 18,747 34,762 54,000 2019 4,721 26,235 2020 8,102 Total $ 636,797 Total outstanding liabilities for unpaid losses and LAE, net of reinsurance $ 331,154 Incurred Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance As of December 31, 2020 For The Years Ended December 31, Accident Year 2014 (unaudited) 2015 (unaudited) 2016 (unaudited) 2017 (unaudited) 2018 (unaudited) 2019 (unaudited) 2020 IBNR (1) Cumulative Number of Claims 2010 and Prior $ 50,395 $ 47,336 $ 47,194 $ 47,287 $ 47,175 $ 47,213 $ 46,828 $ 62 3,037 2011 29,890 28,190 27,767 27,824 28,162 27,956 28,075 229 1,966 2012 48,204 52,010 51,710 50,435 51,231 49,176 48,706 307 2,431 2013 63,442 55,981 53,783 54,790 58,209 64,399 63,323 926 2,202 2014 50,959 54,370 49,449 56,049 51,642 51,062 49,676 1,003 3,944 2015 70,492 70,160 80,196 81,864 83,646 80,438 1,612 5,606 2016 80,830 83,187 88,459 88,023 89,309 4,150 6,658 2017 125,976 158,450 166,304 162,629 7,959 8,352 2018 164,461 164,042 161,831 16,444 10,123 2019 152,423 158,919 39,463 7,015 2020 84,427 60,327 2,703 Total $ 974,161 $ 132,482 54,037 (1) Total of IBNR plus expected development on reported losses. Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance F
Short-duration Insurance Contracts, Reconciliation Of Net Loss Reserves Prior To Provision For Bad Debt	The table below reconciles the net loss reserves, prior to provisions for bad debt, fair value adjustments, deferred charge assets and deferred gain liabilities and ULAE as of December 31, 2020, by significant line of business to the line of business table presented above: 2020 Total Net Reserves per all Acquisition Years Provision for Bad Debt Total Net Reserves Asbestos $ 1,563,706 $ 22,417 $ 1,586,123 Environmental 261,387 3,661 265,048 General casualty 1,732,445 7,256 1,739,701 Workers' compensation/personal accident 1,687,272 1,737 1,689,009 Marine, aviation and transit 283,868 2,010 285,878 Construction defect 106,135 13 106,148 Professional indemnity/Directors & Officers 833,085 597 833,682 Motor 732,268 2,405 734,673 Property 130,309 1,699 132,008 All Other 256,695 6,648 263,343 Total $ 7,587,170 $ 48,443 $ 7,635,613
Reconciliation of Incurred and Paid Loss Development to Liability for Unpaid Losses and LAE	The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below: 2020 Liabilities for unpaid losses and allocated LAE, net of reinsurance $ 331,154 Reinsurance recoverable on unpaid losses 61,082 Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments $ 392,236 The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below: 2020 Liabilities for unpaid losses and allocated LAE, net of reinsurance $ 252,110 Reinsurance recoverable on unpaid losses 64,536 Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments $ 316,646 The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below: 2020 Liabilities for unpaid losses and allocated LAE, net of reinsurance $ 222,548 Reinsurance recoverable on unpaid losses 217,427 Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments $ 439,975 The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below: 2020 Liabilities for unpaid losses and allocated LAE, net of reinsurance $ 60,340 Reinsurance recoverable on unpaid losses 60,353 Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments $ 120,693 The reconciliation of incurred and paid loss development to the liability for unpaid losses and LAE as presented in the tables above for the year ended December 31, 2020 is set forth below: 2020 Liabilities for unpaid losses and allocated LAE, net of reinsurance $ 23,633 Reinsurance recoverable on unpaid losses — Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments $ 23,633
Average Annual Duration of Claims	The following is unaudited supplementary information, which presents the annual percentage payout since the year of acquisition, by year of acquisition and significant line of business within each acquisition year: Annual Percentage Payout of Incurred Losses since Year of Acquisition, Net of Reinsurance Year of Acquisition Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 2011 - All lines of business 25.68 % 17.45 % (3.59) % (28.95) % (2.12) % 3.57 % (3.49) % 4.99 % 11.18 % 8.86 % 2012 - All lines of business 1.30 % 26.42 % 16.71 % 12.48 % 10.00 % 4.47 % 5.48 % 4.17 % 2.12 % 2013 - All lines of business 25.96 % 21.67 % 15.93 % 11.01 % 6.15 % 3.89 % 2.24 % 0.32 % 2014 - All lines of business 33.84 % 24.15 % 11.11 % 8.07 % 3.74 % 1.65 % 1.10 % 2015 - All lines of business 17.33 % 17.09 % 12.84 % 9.80 % 7.69 % 4.65 % 2015 - Workers' compensation 13.72 % 17.09 % 12.73 % 9.73 % 6.71 % 4.27 % 2016 - All lines of business 7.67 % 9.18 % 7.99 % 8.41 % 6.86 % 2016 - Workers' Compensation 10.33 % 8.96 % 7.09 % 9.89 % 8.22 % 2017 - All lines of business 8.04 % 7.64 % 6.71 % 6.11 % 2018 - All lines of business 12.86 % 25.40 % 12.00 % 2018 - General Casualty 11.31 % 21.69 % 17.77 % 2018 - Workers' Compensation 2.03 % 19.49 % 10.03 % 2018 - Professional Indemnity/Directors & Officers 19.55 % 14.40 % 5.34 % 2018 - Motor 11.08 % 38.47 % 17.61 % 2019 - All lines of business 11.11 % 12.68 % 2019 - General Casualty 8.82 % 7.43 % 2019 - Workers' Compensation 3.67 % 2.02 % 2020 - All lines of business 11.43 % 2020 - General Casualty 3.32 % 2020 - Motor 32.78 % 2020 - Professional Indemnity/Directors & Officers 1.30 % Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 Casualty 7.72 % 20.87 % 17.53 % 15.99 % 9.96 % 4.35 % 7.85 % 9.00 % 0.06 % 0.08 % The following is unaudited supplementary information for average annual historical duration of claims: Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 Marine 18.17 % 30.97 % 19.08 % 9.99 % 5.02 % 2.46 % 3.48 % 2.04 % 0.99 % 0.39 % The following is unaudited supplementary information for average annual historical duration of claims: Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 Property 19.10 % 28.75 % 26.40 % 8.35 % 2.47 % 2.69 % 1.55 % 1.01 % 0.02 % 0.30 % Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 Aerospace 32.80 % 29.84 % 15.40 % 4.61 % 4.31 % 2.22 % 1.93 % 1.12 % 0.48 % 0.01 % Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 Workers' compensation 14.40 % 29.38 % 20.46 % 11.77 % 5.19 % 2.57 % 1.61 % — % — % — %

Defendant Asbestos and Enviro_2

Defendant Asbestos and Environmental Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Liability for Asbestos and Environmental Claims [Abstract]
Schedule Of Liability For Asbestos And Liability Claims	2020 2019 Defendant asbestos and environmental liabilities: Defendant asbestos liabilities $ 913,276 $ 1,100,593 Defendant environmental liabilities 12,572 10,279 Estimated future expenses 42,510 51,637 Fair value adjustments (262,029) (314,824) Defendant asbestos and environmental liabilities 706,329 847,685 Insurance balances recoverable: Insurance recoveries related to defendant asbestos liabilities (net of allowance: 2020 - $4,824) 310,602 549,593 Fair value adjustments (60,950) (100,738) Insurance balances recoverable 249,652 448,855 Net liabilities relating to defendant asbestos and environmental exposures $ 456,677 $ 398,830
Reconciliation of Asbestos and Environmental Liabilities	The table below provides a consolidated reconciliation of the beginning and ending liability for defendant asbestos and environmental exposures for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Balance as of January 1 847,685 203,320 219,164 Less: Insurance balances recoverable 448,855 135,808 122,326 Plus: Cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible insurance balances (1) 3,167 — — Net balance as of January 1 401,997 67,512 96,838 Total net recoveries (paid claims) 153,964 (10,434) (6,351) Amounts recorded in other income (expense): Change in estimate of net ultimate liabilities (103,166) (4,263) (23,221) Reduction in estimated future expenses (9,126) (3,274) — Amortization of fair value adjustments 13,008 13,500 246 Total other expense (income) (99,284) 5,963 (22,975) Acquired on purchase of subsidiaries — 335,789 — Net balance as of December 31 456,677 398,830 67,512 Plus: Insurance balances recoverable (2) 249,652 448,855 135,808 Balance as of December 31 706,329 847,685 203,320 (1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 1 - "Significant Accounting Policies" for further details. (2) Net of allowance for estimated uncollectible insurance balances.
Reconciliation of Allowance for Estimated Uncollectible Insurance Balances	The table below provides a reconciliation of the beginning and ending allowance for estimated uncollectible insurance balances related to our defendant asbestos liabilities, for the years ended December 31, 2020 and 2019: 2020 2019 Allowance for estimated uncollectible insurance balances, beginning of year $ 3,818 $ — Cumulative effect of change in accounting principle 3,167 — Current period change in the allowance (2,161) 3,818 Allowance for estimated uncollectible insurance balances, end of year $ 4,824 $ 3,818

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Categorized Investments Recorded at Fair Value among Levels	We have categorized our assets and liabilities that are recorded at fair value on a recurring basis among levels based on the observability of inputs, or at fair value using NAV per share (or its equivalent) as follows: December 31, 2020 Quoted Prices in Significant Significant Fair Value Based on NAV as Practical Expedient Total Fair Investments: Short-term and Fixed maturity investments: U.S. government and agency $ — $ 951,048 $ — $ — $ 951,048 U.K. government — 51,082 — — 51,082 Other government — 502,153 — — 502,153 Corporate — 5,686,732 — — 5,686,732 Municipal — 162,669 — — 162,669 Residential mortgage-backed — 553,945 — — 553,945 Commercial mortgage-backed — 854,090 — — 854,090 Asset-backed — 557,460 — — 557,460 $ — $ 9,319,179 $ — $ — $ 9,319,179 Other assets included within funds held - directly managed — 14,627 — — 14,627 Equities: Publicly traded equity investments $ 229,167 $ 31,600 $ — $ — $ 260,767 Exchange-traded funds 311,287 — — — 311,287 Privately held equity investments — — 274,741 — 274,741 $ 540,454 $ 31,600 $ 274,741 $ — $ 846,795 Other investments: Hedge funds $ — $ — $ — $ 2,638,339 $ 2,638,339 Fixed income funds — 285,837 — 266,704 552,541 Equity funds — 5,073 — 185,694 190,767 Private equity funds — — — 363,103 363,103 CLO equities — 128,083 — — 128,083 CLO equity funds — — — 166,523 166,523 Private credit funds — — 9,250 183,069 192,319 Other — — 314 12,045 12,359 $ — $ 418,993 $ 9,564 $ 3,815,477 $ 4,244,034 Total Investments $ 540,454 $ 9,784,399 $ 284,305 $ 3,815,477 $ 14,424,635 Cash and cash equivalents $ 385,790 $ 208,272 $ — $ — $ 594,062 Reinsurance balances recoverable on paid and unpaid losses: $ — $ — $ 520,830 $ — $ 520,830 Other Assets: Derivatives qualifying as hedging $ — $ 1,169 $ — $ — $ 1,169 Derivatives not qualifying as hedges — 2,964 — — 2,964 Derivative instruments $ — $ 4,133 $ — $ — $ 4,133 Losses and LAE: $ — $ — $ 2,452,920 $ — $ 2,452,920 Other Liabilities: Derivatives qualifying as hedging $ — $ 28,947 $ — $ — $ 28,947 Derivatives not qualifying as hedges — 5,195 — — 5,195 Derivative instruments $ — $ 34,142 $ — $ — $ 34,142 December 31, 2019 Quoted Prices in Significant Significant Fair Value Based on NAV as Practical Expedient Total Fair Investments: Short-term and Fixed maturity investments: U.S. government and agency $ — $ 696,077 $ — $ — $ 696,077 U.K government — 161,772 — — 161,772 Other government — 702,856 — — 702,856 Corporate — 5,448,270 — — 5,448,270 Municipal — 140,687 — — 140,687 Residential mortgage-backed — 400,914 — — 400,914 Commercial mortgage-backed — 813,746 — — 813,746 Asset-backed — 670,235 — — 670,235 $ — $ 9,034,557 $ — $ — $ 9,034,557 Other assets included within funds held - directly managed $ — $ 14,207 $ — $ — $ 14,207 Equities: Publicly traded equity investments $ 297,310 $ 30,565 $ — $ — $ 327,875 Exchange-traded funds 133,047 — — — 133,047 Privately held equity investments — — 265,799 — 265,799 $ 430,357 $ 30,565 $ 265,799 $ — $ 726,721 Other investments: Hedge funds $ — $ — $ — $ 1,121,904 $ 1,121,904 Fixed income funds — 398,143 — 82,896 481,039 Equity funds — 111,040 — 299,109 410,149 Private equity funds — — — 323,496 323,496 CLO equities — — 87,555 — 87,555 CLO equity funds — — — 87,509 87,509 Other — 34 314 6,031 6,379 $ — $ 509,217 $ 87,869 $ 1,920,945 $ 2,518,031 Total Investments $ 430,357 $ 9,588,546 $ 353,668 $ 1,920,945 $ 12,293,516 Cash and cash equivalents $ 144,984 $ 222,191 $ — $ — $ 367,175 Reinsurance balances recoverable on paid and unpaid losses: $ — $ — $ 695,518 $ — $ 695,518 Other Assets: Derivatives qualifying as hedging $ — $ 642 $ — $ — $ 642 Derivatives not qualifying as hedges — 1,369 — — 1,369 Derivative instruments $ — $ 2,011 $ — $ — $ 2,011 Losses and LAE: $ — $ — $ 2,621,122 $ — $ 2,621,122 Other Liabilities: Derivatives qualifying as hedging $ — $ 11,452 $ — $ — $ 11,452 Derivatives not qualifying as hedges — 4,106 — — 4,106 Derivative instruments $ — $ 15,558 $ — $ — $ 15,558
Reconciliation of Beginning and Ending Balances for All Investments Measured at Fair Value on Recurring Basis	The following tables present a reconciliation of the beginning and ending balances for all investments measured at fair value on a recurring basis using Level 3 inputs during the years ended December 31, 2020 and 2019: 2020 Privately-held Equities Other Investments Total Beginning fair value $ 265,799 $ 87,869 $ 353,668 Purchases 20,125 47,092 67,217 Sales — (1,289) (1,289) Total realized and unrealized losses (11,183) (40,368) (51,551) Transfer out of Level 3 into Level 2 — (83,740) (83,740) Ending fair value $ 274,741 $ 9,564 $ 284,305 2019 Fixed maturity investments Privately-held Equities Other Investments Total Corporate Residential mortgage-backed Commercial mortgage-backed Asset-backed Beginning fair value $ 37,386 $ — $ 7,389 $ 9,121 $ 228,710 $ 39,367 $ 321,973 Purchases 184 — — — 30,713 56,908 87,805 Sales (3,520) — (784) (3,605) (2,016) (590) (10,515) Total realized and unrealized gains (losses) 90 (1) 64 255 8,392 (7,816) 984 Transfer into Level 3 from Level 2 3,535 102 1,515 21,024 — — 26,176 Transfer out of Level 3 into Level 2 (37,675) (101) (8,184) (26,795) — — (72,755) Ending fair value $ — $ — $ — $ — $ 265,799 $ 87,869 $ 353,668 The following table presents a reconciliation of the beginning and ending balances for all insurance contracts measured at fair value on a recurring basis using Level 3 inputs during the years ended December 31, 2020 and 2019: 2020 2019 Liability for losses and LAE Reinsurance balances recoverable on paid and unpaid losses Net Liability for losses and LAE Reinsurance balances recoverable on paid and unpaid losses Net Beginning fair value $ 2,621,122 $ 695,518 $ 1,925,604 $ 2,874,055 $ 739,591 $ 2,134,464 Assumed business 1,526 (180,972) 182,498 9,218 — 9,218 Incurred losses and LAE: Reduction in estimates of ultimate losses (73,596) 59,478 (133,074) (32,690) (2,958) (29,732) Reduction in unallocated LAE (17,484) — (17,484) (19,915) — (19,915) Change in fair value 157,965 38,919 119,046 160,630 43,449 117,181 Total incurred losses and LAE 66,885 98,397 (31,512) 108,025 40,491 67,534 Paid losses (300,234) (101,326) (198,908) (416,770) (92,145) (324,625) Effect of exchange rate movements 63,621 9,213 54,408 46,594 7,581 39,013 Ending fair value $ 2,452,920 $ 520,830 $ 1,932,090 $ 2,621,122 $ 695,518 $ 1,925,604 The net assumed business of $182.5 million in the current period relates to the Hannover Re novation transaction disclosed in Note 4 - "Significant New Business." Changes in fair value in the table above are included in net incurred losses and LAE in our consolidated statements of earnings. The following table presents the components of the net change in fair value for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Changes in fair value due to changes in: Duration $ 20,861 $ 22,719 $ 74,011 Corporate bond yield 96,478 94,462 (71,031) Weighted cost of capital (5,048) — Risk cost of capital 6,755 — 3,684 Change in fair value $ 119,046 $ 117,181 $ 6,664
Valuation Techniques and Inputs	The table below presents the quantitative information related to the fair value measurements for our privately held equity investments measured at fair value on a recurring basis using Level 3 inputs: Quantitative Information about Level 3 Fair Value Measurements Fair Value as of December 31, 2020 Valuation Techniques Unobservable Input Average (1) (in millions of U.S. dollars) $ 230.3 Guideline company methodology Distribution waterfall 12.98 $ 54.0 Cost as approximation of fair value Cost as approximation of fair value $ 284.3 (1) The average represents the arithmetic average of the inputs and is not weighted by the relative fair value.
Reconciliation of Beginning and Ending Balances for All Investments Measured at Fair Value on Recurring Basis	The following table presents a reconciliation of the beginning and ending balances for all insurance contracts measured at fair value on a recurring basis using Level 3 inputs during the years ended December 31, 2020 and 2019: 2020 2019 Liability for losses and LAE Reinsurance balances recoverable on paid and unpaid losses Net Liability for losses and LAE Reinsurance balances recoverable on paid and unpaid losses Net Beginning fair value $ 2,621,122 $ 695,518 $ 1,925,604 $ 2,874,055 $ 739,591 $ 2,134,464 Assumed business 1,526 (180,972) 182,498 9,218 — 9,218 Incurred losses and LAE: Reduction in estimates of ultimate losses (73,596) 59,478 (133,074) (32,690) (2,958) (29,732) Reduction in unallocated LAE (17,484) — (17,484) (19,915) — (19,915) Change in fair value 157,965 38,919 119,046 160,630 43,449 117,181 Total incurred losses and LAE 66,885 98,397 (31,512) 108,025 40,491 67,534 Paid losses (300,234) (101,326) (198,908) (416,770) (92,145) (324,625) Effect of exchange rate movements 63,621 9,213 54,408 46,594 7,581 39,013 Ending fair value $ 2,452,920 $ 520,830 $ 1,932,090 $ 2,621,122 $ 695,518 $ 1,925,604 The net assumed business of $182.5 million in the current period relates to the Hannover Re novation transaction disclosed in Note 4 - "Significant New Business." Changes in fair value in the table above are included in net incurred losses and LAE in our consolidated statements of earnings. The following table presents the components of the net change in fair value for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Changes in fair value due to changes in: Duration $ 20,861 $ 22,719 $ 74,011 Corporate bond yield 96,478 94,462 (71,031) Weighted cost of capital (5,048) — Risk cost of capital 6,755 — 3,684 Change in fair value $ 119,046 $ 117,181 $ 6,664
Quantitative Information	Below is a summary of the quantitative information regarding the significant observable and unobservable inputs used in the internal model to determine fair value on a recurring basis as of December 31, 2020 and 2019: 2020 2019 Valuation Technique Unobservable (U) and Observable (O) Inputs Weighted Average Weighted Average Internal model Corporate bond yield (O) A rated A rated Internal model Credit spread for non-performance risk (U) 0.2% 0.2% Internal model Risk cost of capital (U) 5.1% 5.1% Internal model Weighted average cost of capital (U) 8.25% 8.5% Internal model Duration - liability (U) 8.17 years 7.82 years Internal model Duration - reinsurance balances recoverable on paid and unpaid losses (U) 8.23 years 8.68 years

Premiums Written and Earned (Ta

Premiums Written and Earned (Tables)	12 Months Ended
	Dec. 31, 2020
Insurance [Abstract]
Schedule of Net Premiums Written and Earned	The following tables provide the total reinsurance balances recoverable on paid and unpaid losses. December 31, 2020 Non-life StarStone Total Recoverable from reinsurers on unpaid: Outstanding losses $ 938,231 $ 263,638 $ 1,201,869 IBNR 508,082 139,761 647,843 ULAE 16,688 — 16,688 Fair value adjustments - acquired companies (14,014) (1,339) (15,353) Fair value adjustments - fair value option (21,427) — (21,427) Total reinsurance reserves recoverable 1,427,560 402,060 1,829,620 Paid losses recoverable 172,309 87,234 259,543 Total $ 1,599,869 $ 489,294 $ 2,089,163 Reconciliation to Consolidated Balance Sheet: Reinsurance balances recoverable on paid and unpaid losses $ 1,079,039 $ 489,294 $ 1,568,333 Reinsurance balances recoverable on paid and unpaid losses - fair value option 520,830 — 520,830 Total $ 1,599,869 $ 489,294 $ 2,089,163 December 31, 2019 Non-life Atrium StarStone Total Recoverable from reinsurers on unpaid: Outstanding losses $ 972,293 $ 9,011 $ 264,131 $ 1,245,435 IBNR 673,059 19,286 93,185 785,530 Fair value adjustments - acquired companies (13,652) 519 (2,122) (15,255) Fair value adjustments - fair value option (88,086) — — (88,086) Total reinsurance reserves recoverable 1,543,614 28,816 355,194 1,927,624 Paid losses recoverable 181,375 1,541 70,594 253,510 Total $ 1,724,989 $ 30,357 $ 425,788 $ 2,181,134 Reconciliation to Consolidated Balance Sheet: Reinsurance balances recoverable on paid and unpaid losses $ 1,029,471 $ 30,357 $ 425,788 $ 1,485,616 Reinsurance balances recoverable on paid and unpaid losses - fair value option 695,518 — — 695,518 Total $ 1,724,989 $ 30,357 $ 425,788 $ 2,181,134 The following tables show our gross and net balances recoverable from our reinsurers as well as the related allowance for estimated uncollectible reinsurance broken down by the credit ratings of our reinsurers. The majority of the allowance for estimated uncollectible reinsurance relates to the Non-life Run-off segment. December 31, 2020 Gross Allowance for estimated uncollectible reinsurance Net Provisions as a Reinsurers rated A- or above $ 1,464,529 $ 60,801 $ 1,403,728 4.2 % Reinsurers rated below A-, secured 608,999 — 608,999 — % Reinsurers rated below A-, unsecured 152,757 76,321 76,436 50.0 % Total $ 2,226,285 $ 137,122 $ 2,089,163 6.2 % December 31, 2019 Gross Allowance for estimated uncollectible reinsurance Net Provisions as a Reinsurers rated A- or above $ 1,731,270 $ 43,427 $ 1,687,843 2.5 % Reinsurers rated below A-, secured 463,840 — 463,840 — % Reinsurers rated below A-, unsecured 133,663 104,212 29,451 78.0 % Total $ 2,328,773 $ 147,639 $ 2,181,134 6.3 % The following tables provide a summary of net premiums written and earned for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Premiums Premiums Premiums Premiums Premiums Premiums Non-life Run-off Gross $ 5,191 $ 71,522 $ (25,069) $ 197,009 $ (8,910) $ 25,230 Ceded (2,204) (12,827) (269) (28,513) (307) (15,803) Net $ 2,987 $ 58,695 $ (25,338) $ 168,496 $ (9,217) $ 9,427 Atrium Gross $ 206,656 $ 197,492 $ 192,373 $ 182,678 $ 171,494 $ 164,428 Ceded (23,462) (22,099) (20,017) (18,619) (18,006) (18,113) Net $ 183,194 $ 175,393 $ 172,356 $ 164,059 $ 153,488 $ 146,315 StarStone Gross $ 326,695 $ 441,015 $ 472,815 $ 549,299 $ 622,570 $ 647,218 Ceded (93,493) (122,900) (93,292) (98,187) (144,561) (132,055) Net $ 233,202 $ 318,115 $ 379,523 $ 451,112 $ 478,009 $ 515,163 Other Gross $ 13,441 $ 19,889 $ 18,534 $ 20,544 $ 32,378 $ 25,237 Ceded — — (22) (164) (311) (363) Net $ 13,441 $ 19,889 $ 18,512 $ 20,380 $ 32,067 $ 24,874 Total Gross $ 551,983 $ 729,918 $ 658,653 $ 949,530 $ 817,532 $ 862,113 Ceded (119,159) (157,826) (113,600) (145,483) (163,185) (166,334) Net $ 432,824 $ 572,092 $ 545,053 $ 804,047 $ 654,347 $ 695,779

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill and Intangible Assets	The following table presents a reconciliation of the beginning and ending goodwill and intangible assets, included within other assets in the consolidated balance sheets, for the years ended December 31, 2020 and 2019: Goodwill Intangible Intangible assets with an indefinite life Total Balance as of December 31, 2018 $ 109,807 $ 16,887 $ 67,131 $ 193,825 Amortization — (2,257) — (2,257) Balance as of December 31, 2019 $ 109,807 $ 14,630 $ 67,131 $ 191,568 Amortization — (1,524) — (1,524) Impairment losses (StarStone International) (1) (8,000) — (4,000) (12,000) Reclassification to assets held-for-sale (Atrium) (2) (38,848) (13,106) (63,131) (115,085) Balance as of December 31, 2020 $ 62,959 $ — $ — $ 62,959 (1) On June 10, 2020, we announced the StarStone International Run-Off. During the year ended December 31, 2020, we recognized impairment losses of $8.0 million related to the goodwill allocated to StarStone International and $4.0 million on StarStone's Lloyd's syndicate capacity. (2) On August 13, 2020, we announced the Atrium Exchange Transaction, which resulted in the assets and liabilities of the Atrium segment being classified as held-for-sale as of December 31, 2020. Refer to Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations" for further information. The gross carrying value, accumulated amortization and net carrying value of goodwill and intangible assets by segment and by type as of December 31, 2020 and 2019 was as follows: December 31, 2020 December 31, 2019 Gross Accumulated amortization Net Gross Accumulated amortization Net Non-life Run-off segment: Goodwill $ 62,959 $ — $ 62,959 $ 62,959 $ — $ 62,959 Atrium segment: Goodwill — — — 38,848 — 38,848 Intangible assets with a definite life: Distribution channel — — — 20,000 (8,111) 11,889 Brand — — — 7,000 (4,259) 2,741 Intangible assets with an indefinite life: Lloyd’s syndicate capacity — — — 33,031 — 33,031 Management contract — — — 30,100 — 30,100 Total Atrium segment goodwill and intangible assets — — — 128,979 (12,370) 116,609 StarStone segment: Goodwill — — — 8,000 — 8,000 Intangible assets with an indefinite life: Lloyd’s syndicate capacity — — — 4,000 — 4,000 Total StarStone segment goodwill and intangible assets — — — 12,000 — 12,000 Total goodwill and intangible assets $ 62,959 $ — $ 62,959 $ 203,938 $ (12,370) $ 191,568

Debt Obligations and Credit F_2

Debt Obligations and Credit Facilities (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Amounts of Loans Payable Outstanding, and Accrued Interest	Our debt obligations were as follows: Facility Origination Date Term December 31, 2020 December 31, 2019 4.50% Senior Notes due 2022 March 10, 2017 5 years $ 349,253 $ 348,616 4.95% Senior Notes due 2029 May 28, 2019 10 years 494,194 493,600 Total Senior Notes 843,447 842,216 5.75% Junior Subordinated Notes due 2040 August 26, 2020 20 years 344,812 — EGL Revolving Credit Facility August 16, 2018 5 years 185,000 — 2018 EGL Term Loan Facility December 27, 2018 3 years — 348,991 Total debt obligations $ 1,373,259 $ 1,191,207
Interest Income and Interest Expense Disclosure	The table below provides a summary of the total interest expense for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Interest expense on debt obligations $ 57,974 $ 51,245 $ 25,205 Amortization of debt issuance costs 1,331 953 537 Funds withheld balances and other 3 343 (46) Total interest expense $ 59,308 $ 52,541 $ 25,696

Noncontrolling Interest (Tables

Noncontrolling Interest (Tables)	12 Months Ended
	Dec. 31, 2020
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 for the years ended December 31, 2020 and 2019: 2020 2019 Balance at beginning of year $ 438,791 $ 458,543 Capital contributions — 13,127 Dividends paid — (11,556) Net losses attributable to RNCI (27,512) (12,029) Change in unrealized gains (losses) on AFS investments attributable to RNCI 1,517 (126) Change in currency translation adjustments attributable to RNCI (1,397) 10 Change in redemption value of RNCI (46,224) (9,178) Cumulative effect of change in accounting principle attributable to RNCI (1) 261 — Balance at end of year $ 365,436 $ 438,791 (1) The Company adopted ASU 2016-13 and the related amendments on January 1, 2020. Refer to Note 2 - "Significant Accounting Policies" for further details.

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table presents a roll forward of accumulated other comprehensive income (loss): Unrealized gains (losses) arising during the year Cumulative Currency Translation Adjustment Defined Benefit Pension Liability Total Balance, December 31, 2017, net of tax $ 2,440 $ 11,171 $ (3,143) $ 10,468 Unrealized gains (losses) on fixed income available-for-sale investments arising during the year (2,284) — — (2,284) Reclassification adjustment for net realized (gains) losses included in net earnings 63 — — 63 Change in currency translation adjustment — (202) — (202) Decrease in defined benefit pension liability — — 2,156 2,156 Total other comprehensive income (loss) (2,221) (202) 2,156 (267) Other comprehensive (income) loss attributable to RNCI 222 17 — 239 Balance, December 31, 2018, net of tax 441 10,986 (987) 10,440 Unrealized gains (losses) on fixed income available-for-sale investments arising during the year 2,896 — — 2,896 Reclassification adjustment for net realized (gains) losses included in net earnings (3,894) — — (3,894) Change in currency translation adjustment — (2,428) — (2,428) Decrease in defined benefit pension liability — — 42 42 Total other comprehensive income (loss) (998) (2,428) 42 (3,384) Other comprehensive (income) loss attributable to RNCI 125 (10) — 115 Balance, December 31, 2019, net of tax (432) 8,548 (945) 7,171 Unrealized gains (losses) on fixed income available-for-sale investments arising during the year 104,924 — — 104,924 Reclassification adjustment for change in allowance for credit losses recognized in net earnings (509) — — (509) Reclassification adjustment for net realized (gains) losses included in net earnings (18,033) — — (18,033) Reclassification to earnings on disposal of subsidiary (11,856) 34 — (11,822) Change in currency translation adjustment — (2,103) — (2,103) Decrease in defined benefit pension liability — — 1,152 1,152 Total other comprehensive income (loss) 74,526 (2,069) 1,152 73,609 Other comprehensive (income) loss attributable to RNCI (1,518) 1,397 — (121) Balance, December 31, 2020, net of tax $ 72,576 $ 7,876 $ 207 $ 80,659 The following table presents details about the tax effects allocated to each component of other comprehensive income (loss): Before Tax Amount Tax (Expense) Benefit Net of Tax Amount Twelve months ended December 31, 2020 Unrealized gains (losses) on fixed income available-for-sale investments arising during the year $ 115,610 $ (10,686) $ 104,924 Reclassification adjustment for change in allowance for credit losses recognized in net earnings (499) (10) (509) Reclassification adjustment for net realized (gains) losses included in net earnings (19,766) 1,733 (18,033) Reclassification to earnings on disposal of subsidiary (15,008) 3,152 (11,856) Change in currency translation adjustment (2,294) 191 (2,103) Reclassification to earnings on disposal of subsidiary 34 — 34 Decrease in defined benefit pension liability 1,097 55 1,152 Other comprehensive income (loss) $ 79,174 $ (5,565) $ 73,609 In the year ended December 31, 2019 and 2018, the deferred tax (expense) benefit associated with items reported in other comprehensive income (loss) was subject to a full valuation allowance. For information on valuation allowances on deferred tax assets, refer to “Assessment of Valuation Allowance on Deferred Tax Assets” within Note 20 - "Income Taxation." The following table presents details amounts reclassified from accumulated other comprehensive income: Details about AOCI components 2020 2019 2018 Affected Line Item in Statement where Net Earnings are presented Unrealized gains (losses) on fixed income available-for-sale investments 18,682 3,894 (63) Net realized and unrealized gains (losses) 16,591 — — Net earnings from discontinued operations 35,273 3,894 (63) Total before tax (4,875) — — Income tax (expense) 30,398 3,894 (63) Net of tax Currency translation adjustment on disposal of subsidiary (34) — — Net earnings from discontinued operations Total reclassifications for the period, net of tax 30,364 3,894 (63)
Schedule of Reclassification from Accumulated Other Comprehensive Income	The following table provides a reconciliation of the gross realized gains and losses and credit recoveries (losses) on our AFS fixed maturity debt securities that arose during the years ended December 31, 2020, 2019 and 2018 within our continuing and discontinued operations and the offsetting reclassification adjustments included within our consolidated statements of comprehensive income: 2020 2019 2018 Included within continuing operations: Gross realized gains on fixed maturity securities, AFS $ 26,313 $ 4,844 $ 27 Gross realized losses on fixed maturity securities, AFS (7,801) (905) (90) Tax effect (1,623) — — Included within discontinued operations: Gross realized gains on fixed maturity securities, AFS 1,374 12 — Gross realized losses on fixed maturity securities, AFS (120) (57) — Tax effect (110) — — Total reclassification adjustment for net realized gains (losses) included in net earnings $ 18,033 $ 3,894 $ (63) Included within continuing operations: Credit recoveries (losses) on fixed maturity securities, AFS $ 170 $ — $ — Tax effect 3 — — Included within discontinued operations: Credit recoveries (losses) on fixed maturity securities, AFS 329 — — Tax effect 7 — — Total reclassification adjustment for change in allowance for credit losses recognized in net earnings $ 509 $ — $ — The following table presents details amounts reclassified from accumulated other comprehensive income: Details about AOCI components 2020 2019 2018 Affected Line Item in Statement where Net Earnings are presented Unrealized gains (losses) on fixed income available-for-sale investments 18,682 3,894 (63) Net realized and unrealized gains (losses) 16,591 — — Net earnings from discontinued operations 35,273 3,894 (63) Total before tax (4,875) — — Income tax (expense) 30,398 3,894 (63) Net of tax Currency translation adjustment on disposal of subsidiary (34) — — Net earnings from discontinued operations Total reclassifications for the period, net of tax 30,364 3,894 (63)

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Comparison of Basic and Diluted Earnings per Share	The following table sets forth the computation of basic and diluted net earnings per ordinary share for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Numerator: Earnings (loss) per share attributable to Enstar ordinary shareholders: Net earnings (loss) from continuing operations (1) $ 1,711,810 $ 897,825 $ (163,232) Net earnings from discontinued operations (2) 7,534 4,350 878 Net earnings (loss) attributable to Enstar ordinary shareholders $ 1,719,344 $ 902,175 $ (162,354) Denominator: Weighted-average ordinary shares outstanding — basic (3) 21,551,408 21,482,617 20,698,310 Effect of dilutive securities: Share-based compensation plans (4) 208,293 227,878 129,746 Warrants 58,593 64,571 76,120 Weighted-average ordinary shares outstanding — diluted 21,818,294 21,775,066 20,904,176 Earnings (loss) per share attributable to Enstar ordinary shareholders: Basic: Net earnings (loss) from continuing operations $ 79.43 $ 41.80 $ (7.89) Net earnings from discontinued operations 0.35 0.20 0.05 Net earnings (loss) per ordinary share $ 79.78 $ 42.00 $ (7.84) Diluted (5) : Net earnings (loss) from continuing operations $ 78.45 $ 41.23 $ (7.89) Net earnings from discontinued operations 0.35 0.20 0.05 Net earnings (loss) per ordinary share $ 78.80 $ 41.43 $ (7.84) (1) Net earnings (loss) from continuing operations attributable to Enstar ordinary shareholders equals net earnings (loss) from continuing operations, plus net loss (earnings) from continuing operations attributable to noncontrolling interest, less dividends on preferred shares. (2) Net earnings (loss) from discontinued operations attributable to Enstar ordinary shareholders equals net earnings (loss) from discontinued operations, net of income taxes, plus net loss (earnings) from discontinued operations attributable to noncontrolling interest; refer to Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations" for a breakdown by period. (3) Weighted-average ordinary shares for basic earnings per share includes ordinary shares (voting and non-voting) but excludes ordinary shares held in the EB Trust in respect of JSOP awards. (4) Share-based dilutive securities include restricted shares, restricted share units, and performance share units. Certain share-based compensation awards, including the ordinary shares held in the EB Trust in respect of JSOP awards, were excluded from the calculation for the year ended December 31, 2020 because they were anti-dilutive. (5) During a period of loss, the basic weighted average ordinary shares outstanding is used in the denominator of the diluted loss per ordinary share computation as the effect of including potentially dilutive securities would be anti-dilutive.

Share-Based Compensation and _2

Share-Based Compensation and Pensions (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Schedule of Compensation Cost for Share-based Compensation Plans	The table below provides a summary of the compensation costs for all of our share-based compensation plans for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Share-based compensation plans: Restricted shares and restricted share units $ 8,286 $ 6,564 $ 7,641 Performance share units 12,678 23,582 1,968 Cash-settled stock appreciation rights 215 2,575 (3,316) Joint share ownership plan expense 4,296 — — Other share-based compensation plans: Northshore/Atrium incentive plan 971 3,652 2,792 StarStone incentive plan (223) 223 — Deferred compensation and ordinary share plan for non-employee directors 1,183 992 1,155 Employee share purchase plan 339 411 430 Total share-based compensation $ 27,745 $ 37,999 $ 10,670 2020 2019 2018 Defined contribution plans $ 11,791 $ 11,798 $ 11,434 Defined benefit plan 2,975 684 2,243 Total pension expense $ 14,766 $ 12,482 $ 13,677
Restricted Shares, Restricted Share Units and Performance Share Units	The following table summarizes the activity related to restricted shares and restricted share awards during 2020: Number of Shares Weighted-Average Share Price Nonvested — January 1 64,572 $180.49 Granted 70,012 152.28 Vested (38,961) 174.93 Forfeited (373) 177.73 Nonvested — December 31 95,250 161.60 Grant Year Inception-to-date Activity Roll-forward Performance Criteria: Performance Multiplier PSUs Granted Forfeited Estimated Change in Multiplier Vested Unvested at December 31, 2020 Threshold Target Target + Maximum Threshold Target Target + Maximum 2017 36,321 (12,267) 9,527 (33,581) — 20.00 % 30.00 % N/A 40.00 % 50.00 % 100.00 % N/A 150.00 % 2017 91,875 — 18,100 (109,975) — 30.30 % 35.65 % N/A 41.00 % 50.00 % 100.00 % N/A 150.00 % 2018 39,682 (12,545) 10,218 (6,700) 30,655 25.00 % 32.50 % N/A 40.00 % 50.00 % 100.00 % N/A 150.00 % 2019 18,308 (1,758) 7,835 (881) 23,504 20.00 % 30.00 % N/A 40.00 % 60.00 % 100.00 % N/A 150.00 % 2020 22,591 (2,151) — (701) 19,739 25.00 % 32.50 % N/A 40.00 % 60.00 % 100.00 % N/A 150.00 % 2020 52,948 — — — 52,948 33.10 % 36.80 % 44.30 % 52.10 % 50.00 % 100.00 % 150.00 % 200.00 % 261,725 (28,721) 45,680 (151,838) 126,846 The following table summarizes the activity related to PSUs during 2020: Number of Weighted-Average Share Price Nonvested — January 1 206,949 $185.61 Granted 98,099 167.94 Change in performance multiplier 25,850 179.71 Vested (153,469) 187.24 Forfeited (7,442) 146.76 Nonvested — December 31 169,987 174.10
Summary of Performance Share Units and Performance Criteria and Multiplier	The following table summarizes the awards granted, the vested and unvested units at December 31, 2020, and the performance criteria and associated performance multipliers at various levels of achievement. Grant Year Inception-to-date Activity Roll-forward Performance Criteria: Performance Multiplier PSUs Granted Forfeited Estimated Change in Multiplier Vested Unvested at December 31, 2020 Threshold Target Maximum Threshold Target Maximum 2019 18,308 (1,756) 7,811 (930) 23,433 9.60 % 12.00 % 14.40 % 60.00 % 100.00 % 150.00 % 2020 22,560 (2,151) — (701) 19,708 9.60 % 12.00 % 14.40 % 60.00 % 100.00 % 150.00 % 40,868 (3,907) 7,811 (1,631) 43,141
Summary of Performance Multipliers	At the end of each reporting period, we estimate the expected performance multiplier, as shown in the table below: Award Description 2020 2019 2018 2017 FDBVPS Type I (30.00% Target Change) 139% (1) 139% 50% 2017 FDBVPS Type II (35.65% Target Change) 120% (1) 120% 50% 2018 FDBVPS 150% (1) 100% 50% 2019 FDBVPS 150% 100% N/A 2019 Average Operating ROE 150% 100% N/A 2020 FDBVPS Type I (32.50% Target Change) 100% N/A N/A 2020 Average Operating ROE 100% N/A N/A 2020 FDBVPS Type II (36.80% Target Change) 100% N/A N/A (1) Multipliers for the 2017 and 2018 awards are the final achieved terms.
Summary of SARs Activity	The following table summarizes the activity related to SARs during 2020: Number of SARs Weighted-Average Exercise Price of SARs Weighted-Average Expected Term (in years) Aggregate Intrinsic Value (1) Balance, beginning of year 89,227 $ 143.33 Exercised (12,793) 136.94 Balance, end of year 76,434 144.40 1.90 $ 4,623 (1) The aggregate intrinsic value is calculated as the pre-tax difference between the exercise price of the underlying share awards and the closing price per share of our ordinary shares of $204.89 on December 31, 2020.
Assumptions Used to Estimate Fair Value of SARs Using Black-Scholes Option Valuation Model	The following table sets forth the assumptions used to estimate the fair value of the SARs using the Black-Scholes option valuation model as of December 31, 2020, 2019 and 2018: 2020 2019 2018 Weighted-average fair value per SAR $ 78.47 $ 76.03 $ 45.85 Weighted-average volatility 49.43 % 19.75 % 18.94 % Weighted-average risk-free interest rate 0.15 % 1.64 % 2.72 % Dividend yield 0.00 % 0.00 % 0.00 %
Share-Based Compensation Arrangement By Share-Based Payment Award, Valuation Assumptions	The accounting for stock-settled JSOP awards is similar to options, whereby the grant date fair value of $13.6 million is expensed over the life of the award. To determine the grant date fair value of $24.13 per share, we utilized a Monte-Carlo valuation model with the following assumptions: 2020 Weighted-average volatility 18.66 % Weighted-average risk-free interest rate 1.55 % Dividend yield 0.00 %

Income Taxation (Tables)

Income Taxation (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Earnings before Income Taxes	The following table presents earnings (loss) before income taxes by jurisdiction attributable to continuing operations, including earnings from equity method investments, for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Domestic (Bermuda) $ 1,503,505 $ 576,338 $ (232,743) Foreign 231,444 356,878 15,293 Total earnings (loss) before income taxes attributable to continuing operations $ 1,734,949 $ 933,216 $ (217,450)
Tax Expense for Income Taxes	The following table presents our current and deferred income tax expense (benefit) attributable to continuing operations by jurisdiction for the years ended December 31, 2020, 2019 and 2018: 2020 2019 2018 Current: Domestic (Bermuda) $ — $ — $ — Foreign 15,232 16,330 (917) 15,232 16,330 (917) Deferred: Domestic (Bermuda) — — — Foreign 8,595 (3,958) (2,772) 8,595 (3,958) (2,772) Total income tax expense (benefit) attributable to continuing operations $ 23,827 $ 12,372 $ (3,689)
Reconciliation of Earnings before Income Taxes Computed by Applying Effective Rate	The actual effective income tax rate differs from the statutory rate of 0 percent under Bermuda law to earnings (loss) attributable to continuing operations before income taxes, including earnings (loss) from equity method investments for the years ended December 31, 2020, 2019 and 2018 as shown in the following reconciliation: 2020 2019 2018 Earnings (loss) before income taxes $ 1,734,949 $ 933,216 $ (217,450) Bermuda income taxes at statutory rate 0.0 % 0.0 % 0.0 % Foreign income tax rate differential 1.2 % 8.6 % 0.6 % Change in valuation allowance 0.1 % (7.2) % (1.8) % U.S. base erosion and anti-abuse tax — % 0.3 % (0.3) % Other 0.1 % (0.4) % 3.2 % Effective tax rate 1.4 % 1.3 % 1.7 %
Components of Deferred Tax Assets and Deferred Tax Liabilities	Significant components of the deferred tax assets and deferred tax liabilities as of December 31, 2020 and 2019 were as follows: 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 141,459 $ 144,609 Insurance reserves 22,238 7,535 Unearned premiums 68 151 Provisions for bad debt 407 6,172 Defendant asbestos and environmental liabilities 121,006 140,000 Other deferred tax assets 16,696 3,230 Deferred tax assets 301,874 301,697 Valuation allowance (118,229) (117,390) Deferred tax assets, net of valuation allowance 183,645 184,307 Deferred tax liabilities: Unrealized gains on investments (20,185) (14,079) Lloyd's underwriting profit taxable in future periods (15,555) (8,852) Deferred policy acquisition cost — (8,267) Other deferred tax liabilities (9,242) (13,390) Deferred tax liabilities (44,982) (44,588) Net deferred tax asset $ 138,663 $ 139,719 Net Deferred Tax Asset (Liability) Balance by Major Jurisdiction: December 31, 2020 2019 Net Deferred Tax Net Deferred Tax United States $ 156,730 $ 154,700 United Kingdom (18,095) (16,074) Other 28 1,093 Total $ 138,663 $ 139,719
Summary of Operating Loss Carryforwards	As of December 31, 2020, we had net operating loss carryforwards that could be available to offset future taxable income, as follows: Tax Jurisdiction Loss Carryforwards Tax effect Expiration Operating and Capital Loss Carryforwards: United States - Net operating loss $ 428,732 $ 90,034 2024-2038 United Kingdom 185,230 35,194 Indefinitely Luxembourg 17,200 4,300 2035-2036 Other 48,683 11,931 Indefinitely
Summary of Income Tax Examinations	Listed below are the tax years that remain subject to examination by a major tax jurisdiction as of December 31, 2020: Major Tax Jurisdiction Open Tax Years United States 2017-2020 United Kingdom 2019-2020 Australia 2015-2020

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	The following table presents the amounts included in our consolidated balance sheet related to our related party transactions with Stone Point and its affiliated entities: December 31, 2020 December 31, 2019 Short-term investments, AFS, at fair value $ 878 $ 1,431 Fixed maturities, trading, at fair value 196,086 269,131 Fixed maturities, AFS, at fair value 227,397 160,303 Equities, at fair value 103,914 121,794 Other investments, at fair value: Hedge funds 19,844 18,993 Fixed income funds 210,017 381,449 Private equity funds 37,262 34,858 CLO equities 38,658 32,560 CLO equity funds 166,523 87,509 Private Debt 27,016 16,312 Real estate fund 27,278 18,106 Total investments 1,054,873 1,142,446 Cash and cash equivalents 23,933 54,080 Other assets 403 10 Other liabilities 745 4,710 Net investment $ 1,078,464 $ 1,191,826 The following table presents the amounts included in net earnings related to our related party transactions with Stone Point and its affiliated entities: 2020 2019 2018 Net investment income $ 16,325 $ 8,733 $ 7,424 Net realized and unrealized gains (losses) 23,750 26,631 207 Total net earnings $ 40,075 $ 35,364 $ 7,631 Our consolidated statement of earnings for the year ended December 31, 2018 included the following balances related to transactions between us and KaylaRe and KaylaRe Ltd. up until May 14, 2018, the date of acquisition: 2018 Fee income due to Enstar Limited $ 1,453 Transactions under KaylaRe-StarStone QS: Ceded premium earned (52,651) Net incurred losses 31,654 Acquisition costs 18,774 Total net earnings (loss) $ (770) Our consolidated balance sheet as of December 31, 2020 and 2019 included the following balances related to transactions with Hillhouse Capital and AnglePoint (as applicable): 2020 2019 Investments in funds managed by AnglePoint, held by Enhanzed Re $ 851,435 $ 327,799 Our ownership percentage of Enhanzed Re 47.4 % 47.4 % Our share of investments in funds managed by AnglePoint held by Enhanzed Re (through our equity method investment ownership) $ 403,580 $ 155,377 Investment in other funds managed by AnglePoint and Hillhouse: InRe Fund $ 2,365,158 $ 918,633 Other funds 369,508 232,968 $ 2,734,666 $ 1,151,601 As noted above, Clear Spring was not a related party as of December 31, 2020. Our consolidated balance sheet as of December 31, 2019 included the following balances between us and Clear Spring: 2019 Balances under StarStone ceding quota share included, in assets or liabilities held-for-sale: Reinsurance balances recoverable on paid and unpaid losses $ 22,812 Prepaid insurance premiums 51 Ceded payable 3,616 Ceded acquisition costs 21 Balances under assuming quota share: Losses and LAE 6,135 Unearned reinsurance premiums 13 Funds held 8,611 Our consolidated statement of earnings for the years ended December 31, 2020, 2019 and 2018 included the following amounts between us and Clear Spring: 2020 2019 2018 Transactions under StarStone ceding quota share, included in net earnings (loss) from discontinued operations: Ceded premium earned $ 122 $ (14,994) (29,520) Net incurred losses and LAE 2,730 6,567 18,143 Acquisition costs 56 356 7,035 Transactions under assuming quota share: Premium earned (15) 3,749 7,380 Net incurred losses and LAE 1,014 (2,202) (4,536) Acquisition costs 11 (92) (1,836) Total net earnings (loss) $ 3,918 $ (6,616) $ (3,334) The following table presents the amounts included in net earnings related to our related party transactions with AmTrust: 2020 2019 2018 Net investment income $ 7,365 $ 7,667 $ 299 Net realized and unrealized gains (11,183) 10,086 — Total net earnings $ (3,818) $ 17,753 $ 299 Our consolidated balance sheet as of December 31, 2020 and 2019 included the following balances between us and Enhanzed Re: 2020 2019 Balances under ceding quota share: Reinsurance balances recoverable $ 208,379 $ 59,601 Funds held 193,981 50,089 Insurance balances payables 1,276 1,443 Other assets 730 1,033 Our consolidated statement of earnings for the years ended December 31, 2020 and 2019 included the following amounts between us and Enhanzed Re: 2020 2019 Amounts under ceding quota share: Ceded premium earned $ (391) $ — Net incurred losses and LAE (5,977) — Acquisition costs 169 73 Net investment income (4,272) — Net realized and unrealized gains (740) — Other income 2,617 — Fees and commission income 572 749 Total Net earnings $ (8,022) $ 822 Change in unrealized gains (losses) on AFS investments $ (2,729) $ — Our consolidated balance sheet as of December 31, 2020 included the following balances between us and Core Specialty: 2020 Balances under assuming quota share, LPT and ADC reinsurances: Funds held by reinsured companies $ 58,086 Other assets 38,846 Losses and loss adjustment expenses 682,637 Insurance and reinsurance balances payable 24,806 Other liabilities 5,003 Balances under ceding reinsurances: Reinsurance balances recoverable on paid and unpaid losses 1,736 Balances under service agreements: Other assets 6,727 Other liabilities 328 Balances under sale and recapitalization agreement: Other liabilities 4,512 Our consolidated statement of earnings for the year ended December 31, 2020 included the following amounts between us and Core Specialty: 2020 Transactions under assuming quota share, LPT and ADC reinsurances: Net premiums earned $ 76 Net incurred losses and loss adjustment expenses (1,223) Acquisition costs 458 Transactions under service agreements: Fees and commission income 4,004 Total net earnings $ 3,315

Dividend Restrictions and Sta_2

Dividend Restrictions and Statutory Financial Information (Tables)	12 Months Ended
	Dec. 31, 2020
Insurance [Abstract]
Summary of Statutory Capital and Surplus	The statutory capital and surplus amounts for the years ended December 31, 2020 and 2019 and statutory net income amounts for the years ended December 31, 2020, 2019 and 2018 for our (re)insurance subsidiaries based in Bermuda, the United Kingdom, Australia, the United States and Continental Europe are summarized in the table below which includes information relating to acquisitions from the year of acquisition: Statutory Capital and Surplus Required Actual Statutory Income 2020 2019 2020 2019 2020 2019 2018 Bermuda $ 2,711,687 $ 2,138,395 $ 5,565,429 $ 4,016,663 $ 1,850,913 $ 643,683 $ 29,486 U.K. 803,685 837,104 1,224,208 1,532,751 43,219 154,644 (52,936) U.S. 185,904 364,507 554,339 861,379 (67,477) 121,406 (75,005) Europe 95,746 94,334 214,115 229,344 (983) 11,816 (17,611) Australia 18,858 18,110 58,531 37,815 (1,722) 4,847 1,761

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Lease, Cost and Other Lease Information	The table below provides the lease cost and other information relating to our operating leases for the years ended December 31, 2020 and 2019: 2020 2019 Lease cost: Operating lease cost $ 12,720 $ 13,627 Short-term lease cost (1) 246 — Total lease cost 12,966 13,627 Sub-lease income (2) (553) (542) Total net lease cost $ 12,413 $ 13,085 Other information: Operating cash paid for amounts included in the measurement of lease liabilities $ 13,421 $ 11,129 Non-cash activity: right-of-use assets relating to leases 295 57,536 Weighted-average remaining lease term 6.1 years 6.3 years Weighted-average discount rate 6.5 % 6.3 % (1) Leases with an initial lease term of twelve months or less are not recognized within our consolidated balance sheets. (2) Sub-lease income consists of rental income received from third parties to whom we have sub-leased some of our leased office spaces and is included within other income in our consolidated statements of earnings.
Assets And Liabilities, Lessee	The table below provides a summary of the operating leases recorded on our consolidated balance sheets for the years ended December 31, 2020 and 2019: Balance sheet classification 2020 2019 Right-of-use assets (1) (2) Other assets $ 32,297 $ 46,747 Current lease liabilities (2) Other liabilities 7,959 11,403 Non-current lease liabilities (2) Other liabilities 27,064 34,785 (1) Following our decision to put the StarStone International operations into orderly run-off effective June 10, 2020, we recorded total impairment charges of $3.5 million on the right-of-use assets relating to certain StarStone International operating leases as of December 31, 2020. (2) The right-of-use assets and the total lease liability balances exclude balances of $1.0 million and $0.8 million respectively, related to Atrium which have been reclassified to held-for-sale balances on our consolidated balance sheet as of December 31, 2020.
Lessee, Operating Lease, Liability, Maturity	The table below provides a summary of the contractual maturities of our operating lease liabilities: 2021 2022 2023 2024 2025 2026 and beyond Total lease payments Less: Imputed interest Present value of lease liabilities Contractual maturities $ 9,774 8,099 7,267 5,561 4,534 8,577 43,812 (8,789) $ 35,023

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Summary of Operations by Segment	2020 Non-life Atrium StarStone Other Total Gross premiums written $ 5,191 $ 206,656 $ 326,695 $ 13,441 $ 551,983 Net premiums written $ 2,987 $ 183,194 $ 233,202 $ 13,441 $ 432,824 Net premiums earned $ 58,695 $ 175,393 $ 318,115 $ 19,889 $ 572,092 Net incurred losses and LAE (44,995) (87,226) (266,738) (16,967) (415,926) Acquisition costs (20,177) (59,611) (90,797) (435) (171,020) Operating expenses (200,990) (13,078) (81,853) — (295,921) Underwriting income (loss) (207,467) 15,478 (121,273) 2,487 (310,775) Net investment income 282,048 5,542 27,443 (12,216) 302,817 Net realized and unrealized gains 1,627,526 4,165 10,328 — 1,642,019 Fees and commission income 19,462 22,984 — — 42,446 Other income (losses) 99,940 131 3,734 (2,673) 101,132 Corporate expenses (97,727) (21,522) (42,011) (44,298) (205,558) Interest income (expense) (67,195) — (2,110) 9,997 (59,308) Net foreign exchange gains (losses) (13,214) 4,327 (10,140) 2,634 (16,393) EARNINGS (LOSS) BEFORE INCOME TAXES 1,643,373 31,105 (134,029) (44,069) 1,496,380 Income tax expense (17,412) (4,122) (902) (1,391) (23,827) Earnings from equity method investments 238,569 — — — 238,569 NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS 1,864,530 26,983 (134,931) (45,460) 1,711,122 Net earnings from discontinued operations, net of income taxes — — 16,251 — 16,251 NET EARNINGS (LOSS) 1,864,530 26,983 (118,680) (45,460) 1,727,373 Net (earnings) loss attributable to noncontrolling interest 1,597 (11,059) 37,133 — 27,671 NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR 1,866,127 15,924 (81,547) (45,460) 1,755,044 Dividends on preferred shares — — — (35,700) (35,700) NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS $ 1,866,127 $ 15,924 $ (81,547) $ (81,160) $ 1,719,344 Underwriting ratios: Loss ratio 49.7 % 83.8 % Acquisition expense ratio 34.0 % 28.5 % Operating expense ratio 7.5 % 25.8 % Combined ratio 91.2 % 138.1 % 2019 Non-life Atrium StarStone Other Total Gross premiums written $ (25,069) $ 192,373 $ 472,815 $ 18,534 $ 658,653 Net premiums written $ (25,338) $ 172,356 $ 379,523 $ 18,512 $ 545,053 Net premiums earned $ 168,496 $ 164,059 $ 451,112 $ 20,380 $ 804,047 Net incurred losses and LAE (51,625) (77,276) (469,240) (16,038) (614,179) Acquisition costs (73,642) (56,956) (109,369) (642) (240,609) Operating expenses (199,756) (14,452) (60,627) — (274,835) Underwriting income (loss) (156,527) 15,375 (188,124) 3,700 (325,576) Net investment income 275,236 7,049 34,396 (8,410) 308,271 Net realized and unrealized gains 968,350 6,195 31,572 5,849 1,011,966 Fees and commission income 18,293 10,160 — — 28,453 Other income 34,809 140 329 1,792 37,070 Corporate expenses (70,689) (13,825) (7,790) (45,945) (138,249) Interest income (expense) (62,055) — (475) 9,989 (52,541) Net foreign exchange gains (losses) 9,918 (504) (1,505) 3 7,912 EARNINGS (LOSS) BEFORE INCOME TAXES 1,017,335 24,590 (131,597) (33,022) 877,306 Income tax expense (7,250) (4,033) (1,004) (85) (12,372) Earnings (losses) from equity method investments 56,128 — (218) — 55,910 NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS 1,066,213 20,557 (132,819) (33,107) 920,844 Net earnings from discontinued operations, net of income taxes — — 7,375 — 7,375 NET EARNINGS (LOSS) 1,066,213 20,557 (125,444) (33,107) 928,219 Net (earnings) loss attributable to noncontrolling interest (6,409) (8,432) 24,711 — 9,870 NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR 1,059,804 12,125 (100,733) (33,107) 938,089 Dividends on preferred shares — — — (35,914) (35,914) NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS $ 1,059,804 $ 12,125 $ (100,733) $ (69,021) $ 902,175 Underwriting ratios: Loss ratio 47.1 % 104.0 % Acquisition expense ratio 34.7 % 24.2 % Operating expense ratio 8.8 % 13.5 % Combined ratio 90.6 % 141.7 % 2018 Non-life Atrium StarStone Other Total Gross premiums written $ (8,910) $ 171,494 $ 622,570 $ 32,378 $ 817,532 Net premiums written $ (9,217) $ 153,488 $ 478,009 $ 32,067 $ 654,347 Net premiums earned $ 9,427 $ 146,315 $ 515,163 $ 24,874 $ 695,779 Net incurred losses and LAE 306,067 (69,810) (543,080) (16,899) (323,722) Acquisition costs (4,006) (50,646) (120,517) (2,686) (177,855) Operating expenses (158,731) (17,777) (98,137) — (274,645) Underwriting income (loss) 152,757 8,082 (246,571) 5,289 (80,443) Net investment income 226,287 5,686 27,000 2,725 261,698 Net realized and unrealized losses (381,712) (3,251) (12,320) (10,249) (407,532) Fees and commission income 16,466 18,622 — — 35,088 Other income (losses) 35,978 162 (550) (1,517) 34,073 Corporate expenses (39,093) (6,921) — (28,127) (74,141) Interest income (expense) (30,616) — (103) 5,023 (25,696) Net foreign exchange gains (losses) 2,534 (3,394) (2,832) 1,048 (2,644) EARNINGS (LOSS) BEFORE INCOME TAXES (17,399) 18,986 (235,376) (25,808) (259,597) Income tax benefit (expense) 3,581 (3,732) 3,892 (52) 3,689 Earnings from equity method investments 42,147 — — — 42,147 NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS 28,329 15,254 (231,484) (25,860) (213,761) Net earnings from discontinued operations, net of income taxes — — 1,489 — 1,489 NET EARNINGS (LOSS) 28,329 15,254 (229,995) (25,860) (212,272) Net (earnings) loss attributable to noncontrolling interest (3,107) (6,257) 71,415 — 62,051 NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR 25,222 8,997 (158,580) (25,860) (150,221) Dividend on preferred shares — — — (12,133) (12,133) NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS $ 25,222 $ 8,997 $ (158,580) $ (37,993) $ (162,354) Underwriting ratios: Loss ratio 47.7 % 105.4 % Acquisition expense ratio 34.6 % 23.4 % Operating expense ratio 12.2 % 19.1 % Combined ratio 94.5 % 147.9 %
Schedule of Revenue from External Customers	The following table summarizes our gross premiums written for the year ended December 31, 2020 by geographic area. Geographic distribution in future years is subject to variation based upon market conditions and business strategies. Non-life Run-off Atrium StarStone Other Total Total % Total % Total % Total % Total % (In thousands of U.S. dollars, except percentages) United States $ 4,969 95.7 $ 103,411 50.1 $ 61,104 18.7 $ 13,441 100.0 $ 182,925 33.2 United Kingdom (229) (4.4) 14,054 6.8 105,057 32.2 — — 118,882 21.5 Europe 1,615 31.1 19,705 9.5 62,181 19.0 — — 83,501 15.1 Asia — — 7,834 3.8 60,262 18.4 — — 68,096 12.3 Rest of World (1,164) (22.4) 61,652 29.8 38,091 11.7 — — 98,579 17.9 Total $ 5,191 100.0 $ 206,656 100.0 $ 326,695 100.0 $ 13,441 100.0 $ 551,983 100.0
Summary of Company's Assets by Segment	Our total assets as of December 31, 2020 and 2019 by segment and for our other activities were as follows: 2020 2019 Assets by Segment: Non-life Run-off (1) $ 19,062,400 $ 15,775,409 Atrium (2) 615,778 580,405 StarStone 2,583,247 3,985,137 Other (614,141) (514,852) Total assets $ 21,647,284 $ 19,826,099 (1) The total assets within the Non-life Run-off segment include assets of $95.5 million related to Arden's operations that have been included within Northshore's held-for-sale assets in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations" and Discontinued Operations." (2) The total assets within the Atrium segment are all included within Northshore's held-for-sale assets in Note 5 - "Divestitures, Held-for-Sale Businesses and Discontinued Operations".

Unaudited Condensed Quarterly_2

Unaudited Condensed Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Unaudited Condensed Quarterly Financial Data	December 31, September 30, June 30, March 31, 2020 2019 2020 2019 2020 2019 2020 2019 INCOME Net premiums earned $ 108,146 $ 185,336 $ 161,724 $ 175,802 $ 142,871 $ 190,962 $ 159,351 $ 251,947 Fees and commission income 14,121 9,522 10,787 6,437 10,010 6,017 7,528 6,477 Net investment income 61,530 76,847 72,130 81,502 94,443 74,271 74,714 75,651 Net realized and unrealized gains (losses) 803,467 153,477 500,005 145,060 967,608 260,669 (629,061) 452,760 Other income (losses) 33,372 21,703 48,404 822 (1,087) 8,831 20,443 5,714 1,020,636 446,885 793,050 409,623 1,213,845 540,750 (367,025) 792,549 EXPENSES Net incurred losses and loss adjustment expenses 76,248 48,068 109,686 163,258 186,692 146,554 43,300 256,299 Acquisition costs 38,202 78,417 37,708 33,310 49,067 51,081 46,043 77,801 General and administrative expenses 142,394 116,780 115,828 97,365 144,830 100,676 98,427 98,263 Interest expense 16,872 13,519 15,003 14,950 14,018 13,036 13,415 11,036 Net foreign exchange losses (gains) 15,018 12,186 8,156 (13,665) 5,158 (2,579) (11,939) (3,854) 288,734 268,970 286,381 295,218 399,765 308,768 189,246 439,545 EARNINGS (LOSS) BEFORE INCOME TAXES 731,902 177,915 506,669 114,405 814,080 231,982 (556,271) 353,004 Income tax benefit (expense) 1,468 12,893 (13,915) (13,465) (16,652) (7,698) 5,272 (4,102) Earnings (losses) from equity method investments 85,844 11,722 149,065 17,703 (8,790) 17,713 12,450 8,772 NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS 819,214 202,530 641,819 118,643 788,638 241,997 (538,549) 357,674 Net earnings (loss) from discontinued operations, net of income taxes 15,441 (4,666) 4,031 7,916 (1,152) (3,943) (2,069) 8,068 NET EARNINGS (LOSS) 834,655 197,864 645,850 126,559 787,486 238,054 (540,618) 365,742 Net (earnings) loss attributable to noncontrolling interest (3,131) 4,900 (21,912) 109 19,992 2,713 32,722 2,148 NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR 831,524 202,764 623,938 126,668 807,478 240,767 (507,896) 367,890 Dividends on preferred shares (8,925) (8,925) (8,925) (8,925) (8,925) (8,925) (8,925) (9,139) NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS $ 822,599 $ 193,839 $ 615,013 $ 117,743 $ 798,553 $ 231,842 $ (516,821) $ 358,751 Earnings (loss) per ordinary share attributable to Enstar ordinary shareholders: Basic: Net earnings (loss) from continuing operations $ 37.91 $ 9.15 $ 28.39 $ 5.26 $ 37.06 $ 10.90 $ (23.93) $ 16.49 Net earnings (loss) from discontinued operations 0.33 (0.13) 0.11 0.22 (0.03) (0.11) (0.05) 0.22 Basic $ 38.24 $ 9.02 $ 28.50 $ 5.48 $ 37.03 $ 10.79 $ (23.98) $ 16.71 Diluted (1) : Net earnings (loss) from continuing operations $ 37.47 $ 9.02 $ 28.13 $ 5.21 $ 36.68 $ 10.81 $ (23.93) $ 16.35 Net earnings (loss) from discontinued operations 0.32 (0.13) 0.11 0.21 (0.03) (0.11) (0.05) 0.22 Net earnings (loss) per ordinary share $ 37.79 $ 8.89 $ 28.24 $ 5.42 $ 36.65 $ 10.70 $ (23.98) $ 16.57 (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.

Description of Business - Addit

Description of Business - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020Segment
Segment Reporting Information [Line Items]
Number of segments	3
Atrium
Segment Reporting Information [Line Items]
Syndicate underwriting capacity percentage	25.00%

Significant Accounting Polici_3

Significant Accounting Policies (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease to retained earnings	$ 4,647,312	$ 2,887,892
Reinsurance recoverable, allowance for credit loss	137,122	147,639	$ 156,732
Allowance for credit losses	$ 322	0
Cumulative effect of change in accounting principle
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease to retained earnings		6,100
Financial instruments, allowance for credit loss		3,000
Reinsurance recoverable, allowance for credit loss		(195)	$ 0
Allowance for credit losses		$ 3,059

Business Acquisitions - Additio

Business Acquisitions - Additional Information (Details)	Oct. 30, 2019USD ($)	Dec. 27, 2018USD ($)	May 14, 2018USD ($)$ / sharesshares	Jun. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	May 13, 2018
Business Acquisition [Line Items]
Asbestos and environmental liabilities						$ 2,100,000,000	$ 2,300,000,000
Goodwill						$ 62,959,000	$ 109,807,000	$ 109,807,000
Ownership percentage						47.40%	47.40%
Morse TEC
Business Acquisition [Line Items]
Cash paid	$ 0
Asbestos and environmental liabilities	700,000,000
Goodwill	0
Gain on bargain purchase	0
Intangible assets acquired	0
Gain on bargain purchase	$ 0
Maiden Re
Business Acquisition [Line Items]
Cash paid		$ 286,375,000
Goodwill		$ 0
KaylaRe
Business Acquisition [Line Items]
Goodwill			$ 41,736,000
Number of Enstar ordinary shares issued (shares) | shares			2,007,017
Closing price of shares (dollars per share) | $ / shares			$ 206.65
Ownership percentage acquired			51.80%
Price-to-book multiple			1.05
Gain recognized on remeasurement of previously held equity method investment to fair value				$ 16,000,000	$ 16,007,000
Loss on settlement of preexisting relationships				$ 15,600,000	$ 15,600,000
Ordinary Shares | KaylaRe
Business Acquisition [Line Items]
Number of Enstar ordinary shares issued (shares) | shares			1,501,778
Series E non-voting convertible ordinary shares | KaylaRe
Business Acquisition [Line Items]
Number of Enstar ordinary shares issued (shares) | shares			505,239
KaylaRe
Business Acquisition [Line Items]
Ownership percentage									48.20%

Business Acquisitions - Summary

Business Acquisitions - Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed as of Date of Acquisition (Details) - USD ($) $ in Thousands	Oct. 30, 2019	Dec. 27, 2018	May 14, 2018
Morse TEC
ASSETS
Cash and cash equivalents	$ 171,412
Deferred tax assets	140,000
Other assets - insurance balances receivable	371,116
TOTAL ASSETS	682,528
LIABILITIES
Defendant asbestos and environmental liabilities	662,507
Other liabilities	20,021
TOTAL LIABILITIES	682,528
NET ASSETS ACQUIRED AT FAIR VALUE	$ 0
Maiden Re
ASSETS
Cash and cash equivalents		$ 12,035
Restricted cash and cash equivalents		26,871
Other assets		96,669
Premiums receivable		138,378
Prepaid reinsurance premiums		3,257
Reinsurance balances recoverable		87,018
TOTAL ASSETS		1,466,329
Fixed maturities, trading, at fair value		1,098,593
Short-term investments, trading, at fair value		3,508
Total investments		1,102,101
LIABILITIES
Other liabilities		56,618
Losses and LAE		1,027,367
Unearned premiums		85,696
TOTAL LIABILITIES		1,169,681
NET ASSETS ACQUIRED AT FAIR VALUE		$ 296,648
KaylaRe
ASSETS
Cash and cash equivalents			$ 5,657
Other assets			614
Premiums receivable			10,965
Deferred acquisition costs			275
TOTAL ASSETS			770,380
Fixed maturities, trading, at fair value			126,393
Short-term investments, trading, at fair value			626,476
Total investments			752,869
LIABILITIES
Other liabilities			9,004
Losses and LAE			4,059
Unearned premiums			10,984
Insurance and reinsurance balances payable			13
TOTAL LIABILITIES			24,060
NET ASSETS ACQUIRED AT FAIR VALUE			$ 746,320

Business Acquisitions - Results

Business Acquisitions - Results of Operations Of Acquiree (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Morse TEC
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net investment income	$ 488
General and administrative expenses	(1,459)
Other expenses	(1,512)
Earnings of acquiree since acquisition date	(2,483)
Maiden Re
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net investment income	675
General and administrative expenses	(435)
Net unrealized gains	3,749
Earnings of acquiree since acquisition date	$ 3,989
KaylaRe
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net investment income		$ 3,096
General and administrative expenses		(2,164)
Net unrealized gains		(47,769)
Earnings of acquiree since acquisition date		(45,915)
Premiums earned		13,627
Incurred losses and LAE		(12,364)
Acquisition costs		(341)
Underwriting income		$ 922

Business Acquisitions - Purchas

Business Acquisitions - Purchase Price and Fair Value of Assets Acquired (Details) $ / shares in Units, $ in Thousands	Dec. 27, 2018USD ($)	May 14, 2018USD ($)$ / sharesshares	Jun. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	May 13, 2018USD ($)
Purchase Price
Excess of purchase price over fair value of net assets acquired					$ 62,959	$ 109,807	$ 109,807
Fair Value of Previously Held Equity Method Investment
Carrying value of previously held equity method investment prior to the close of the transaction					$ 832,295	$ 326,277
Maiden Re
Purchase Price
Cash paid	$ 286,375
Adjustment for the fair value of preexisting relationships	10,273
Purchase price	296,648
Net assets acquired at fair value	296,648
Excess of purchase price over fair value of net assets acquired	$ 0
KaylaRe
Purchase Price
Adjustment for the fair value of preexisting relationships		$ 37,169
Value of ordinary shares issued		414,750
Fair value of previously held equity method investment		336,137
Purchase price		788,056
Net assets acquired at fair value		746,320
Excess of purchase price over fair value of net assets acquired		$ 41,736
Fair Value of Enstar Ordinary Shares Issued
Number of Enstar ordinary shares issued (shares) | shares		2,007,017
Closing price of shares (dollars per share) | $ / shares		$ 206.65
Fair value of Enstar ordinary shares issued to shareholders of KaylaRe		$ 414,750
Fair Value of Previously Held Equity Method Investment
Price-to-book multiple		1.05
Fair value of previously held equity method investment prior to the close of the transaction		$ 336,137
Gain recognized on remeasurement of previously held equity method investment to fair value			$ 16,000	$ 16,007
KaylaRe
Fair Value of Previously Held Equity Method Investment
Carrying value of previously held equity method investment prior to the close of the transaction								$ 320,130

Business Acquisitions - Loss on

Business Acquisitions - Loss on Settlement Of Contractual Preexisting Relationships (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 14, 2018	Dec. 31, 2017
ASSETS
Funds held by reinsured companies	$ 635,819	$ 475,732
Deferred acquisition costs/Value of business acquired	238,602	272,462	$ 86,585		$ 80,192
TOTAL ASSETS	21,647,284	19,826,099
LIABILITIES
Losses and LAE	10,593,282	9,868,404	$ 9,048,796		$ 7,100,488
Insurance and reinsurance balances payable	494,412	420,546
Other liabilities	942,905	994,584
TOTAL LIABILITIES	14,593,844	14,530,957
NET ASSETS (LIABILITIES)	$ 6,688,004	$ 4,856,351
Carrying value | KaylaRe
ASSETS
Funds held by reinsured companies				$ 386,793
Deferred acquisition costs/Value of business acquired				33,549
TOTAL ASSETS				420,342
LIABILITIES
Losses and LAE				339,747
Unearned premiums				105,602
Insurance and reinsurance balances payable				25,897
Other liabilities				1,864
TOTAL LIABILITIES				473,110
NET ASSETS (LIABILITIES)				(52,768)
Fair value | KaylaRe
ASSETS
Funds held by reinsured companies				386,793
Deferred acquisition costs/Value of business acquired				40,268
TOTAL ASSETS				427,061
LIABILITIES
Losses and LAE				333,205
Unearned premiums				105,602
Insurance and reinsurance balances payable				23,559
Other liabilities				1,864
TOTAL LIABILITIES				464,230
NET ASSETS (LIABILITIES)				(37,169)
Loss on deemed settlement | KaylaRe
ASSETS
Funds held by reinsured companies				0
Deferred acquisition costs/Value of business acquired				6,719
TOTAL ASSETS				6,719
LIABILITIES
Losses and LAE				(6,542)
Unearned premiums				0
Insurance and reinsurance balances payable				(2,338)
Other liabilities				0
TOTAL LIABILITIES				(8,880)
NET ASSETS (LIABILITIES)				$ 15,599

Significant New Business (Detai

Significant New Business (Details) - USD ($) $ in Thousands

Feb. 25, 2021

Feb. 05, 2021

Jan. 15, 2021

Jan. 08, 2021

Oct. 01, 2020

Aug. 06, 2020

Jul. 01, 2020

Jun. 01, 2020

Mar. 31, 2020

Oct. 01, 2019

Aug. 05, 2019

Apr. 11, 2019

Feb. 14, 2019

Dec. 31, 2018

Dec. 27, 2018

Aug. 01, 2018

Feb. 23, 2018

Feb. 16, 2018

Jan. 29, 2018

Hannover Re

Schedule of Investments [Line Items]

Total Assets Assumed

$ 182,498

Total Liabilities Assumed

209,713

Fair Value Adjustment

$ (27,215)

Munich Re

Schedule of Investments [Line Items]

Total Assets Assumed

$ 100,956

Total Liabilities Assumed

$ 100,956

AXA Group

Schedule of Investments [Line Items]

Total Assets Assumed

$ 179,681

Total Liabilities Assumed

179,681

Percentage ceded

10.00%

Aspen

Schedule of Investments [Line Items]

Total Assets Assumed

770,000

Deferred Charge Asset

11,746

Total Liabilities Assumed

$ 781,746

Lyft

Schedule of Investments [Line Items]

Total Assets Assumed

$ 465,000

Total Liabilities Assumed

$ 465,000

Zurich

Schedule of Investments [Line Items]

Total Assets Assumed

$ 507,061

Deferred Charge Asset

115,815

Total Liabilities Assumed

$ 622,876

Maiden Re Bermuda

Schedule of Investments [Line Items]

Total Assets Assumed

$ 445,000

$ 70,425

Deferred Charge Asset

85,183

1,704

Total Liabilities Assumed

$ 530,183

$ 72,129

Amerisure

Schedule of Investments [Line Items]

Total Assets Assumed

$ 45,463

Deferred Charge Asset

2,873

Total Liabilities Assumed

$ 48,336

AmTrust

Schedule of Investments [Line Items]

Total Assets Assumed

$ 1,143,949

Deferred Charge Asset

20,633

Total Liabilities Assumed

$ 1,164,582

Allianz SE

Schedule of Investments [Line Items]

Total Assets Assumed

$ 70,000

Total Liabilities Assumed

$ 70,000

Coca-Cola

Schedule of Investments [Line Items]

Total Assets Assumed

$ 103,617

Deferred Charge Asset

17,208

Total Liabilities Assumed

$ 120,825

Zurich Australia

Schedule of Investments [Line Items]

Total Assets Assumed

$ 268,657

Total Liabilities Assumed

280,764

Fair Value Adjustment

$ (12,107)

Neon

Schedule of Investments [Line Items]

Total Assets Assumed

$ 525,673

Total Liabilities Assumed

546,298

Fair Value Adjustment

$ (20,625)

Novae

Schedule of Investments [Line Items]

Total Assets Assumed

$ 1,095,730

Total Liabilities Assumed

1,163,198

Fair Value Adjustment

$ (67,468)

Subsequent Event | AXA Group

Schedule of Investments [Line Items]

Total Liabilities Assumed

$ 1,395,000

Subsequent Event | ProSight

Schedule of Investments [Line Items]

Total Liabilities Assumed

$ 500,000

Subsequent Event | CNA

Schedule of Investments [Line Items]

Total Liabilities Assumed

$ 690,000

Subsequent Event | Liberty Mutual

Schedule of Investments [Line Items]

Total Liabilities Assumed

$ 420,000

Divestitures, Held-For-Sale B_3

Divestitures, Held-For-Sale Businesses and Discontinued Operations - Additional Information (Details) $ in Thousands, € in Millions	Nov. 30, 2020USD ($)	Oct. 14, 2020USD ($)	Oct. 14, 2020EUR (€)	Oct. 02, 2020USD ($)	Dec. 31, 2020USD ($)	Jun. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Jan. 01, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership %					47.40%		47.40%	47.40%
Assumed business							$ 2,186,024	$ 1,586,307	$ 1,772,104
Equity method investments					$ 832,295		$ 832,295	326,277
StarStone US
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assumed business	$ 462,400
Reinsurance premium consideration	478,200
Additional consideration	130,000
Atrium
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Syndicate underwriting capacity percentage							25.00%
Held-for-sale or disposed of by sale, not discontinued operations | Northshore
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restricted investments					94,400		$ 94,400
Discontinued operations, disposed of by sale | StarStone US
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received	235,000				281,989		281,989
Cash consideration received	$ 47,000
Not discontinued operations, disposed of by sale | Vander Haeghen & CO SA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales of subsidiaries, net of cash sold		$ 4,500	€ 3.8
Gain on sale of subsidiary					3,400
Discontinued operations, held-for-sale | StarStone US
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restricted investments								131,000
Cash inflows (outflows)							99,200	$ (53,900)	$ (64,600)
Scenario, Forecast
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments to acquire investments						$ 27,000
Scenario, Forecast | Held-for-sale or disposed of by sale, not discontinued operations | SUL
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales of subsidiaries, net of cash sold						30,000
Core Specialty
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership %										25.23%
Equity method investments					235,000		235,000
Core Specialty | Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership %										25.23%
Inigo
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Investment, fair value					$ 16,900		$ 16,900
Trident | Scenario, Forecast
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments to acquire investments						$ 18,000
Starstone International
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of renewal rights				$ 500
North Bay
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by parent					59.00%		59.00%
North Bay | Trident
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners					39.30%		39.30%
North Bay | Dowling
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners					1.70%		1.70%
SSHL
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by parent					59.00%		59.00%
SSHL | Trident
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners					39.30%		39.30%
SSHL | Dowling
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners					1.70%		1.70%
SSHL | North Bay
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by parent					100.00%		100.00%
Northshore | Trident | Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners										76.30%
Northshore | Dowling | Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners										1.60%
Northshore | North Bay
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by parent					92.10%		92.10%
Northshore | Core Specialty | Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners										13.80%
Core Specialty | Dowling | Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners										0.40%
SUL
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by parent					59.00%		59.00%
SUL | Trident
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners					39.30%		39.30%
SUL | Dowling
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by noncontrolling owners					1.70%		1.70%
Inigo | Scenario, Forecast
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership interest held by parent						5.40%

Divestitures, Held-For-Sale B_4

Divestitures, Held-For-Sale Businesses and Discontinued Operations - Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Nov. 30, 2020
ASSETS
TOTAL ASSETS HELD-FOR-SALE	$ 711,278				$ 1,474,770				$ 711,278	$ 1,474,770
LIABILITIES
TOTAL LIABILITIES HELD-FOR-SALE	483,657				1,208,531				483,657	1,208,531
DISPOSAL
Reclassification to earnings on disposal of subsidiary									(34)	0	$ 0
NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES	15,441	$ 4,031	$ (1,152)	$ (2,069)	(4,666)	$ 7,916	$ (3,943)	$ 8,068	16,251	7,375	1,489
Northshore | Held-for-sale or disposed of by sale, not discontinued operations
ASSETS
Other investments, at fair value	9,897								9,897
Total investments	173,126								173,126
Cash and cash equivalents	71,156								71,156
Restricted cash and cash equivalents	152,044								152,044
Premiums receivable	62,392								62,392
Reinsurance balances recoverable on paid and unpaid losses	37,341								37,341
Funds held by reinsured companies	32,226								32,226
Deferred acquisition costs	24,000								24,000
Other assets	182,993								182,993
TOTAL ASSETS HELD-FOR-SALE	711,278								711,278
LIABILITIES
Losses and loss adjustment expenses	254,149								254,149
Unearned premiums	91,400								91,400
Insurance and reinsurance balances payable	12,393								12,393
Debt obligations	39,850								39,850
Other liabilities	177,265								177,265
TOTAL LIABILITIES HELD-FOR-SALE	483,657								483,657
NET ASSETS HELD-FOR-SALE	227,621								227,621
Northshore | Held-for-sale or disposed of by sale, not discontinued operations | Short-term Investments
ASSETS
AFS, at fair value	1,720								1,720
Northshore | Held-for-sale or disposed of by sale, not discontinued operations | Fixed maturity investments, trading
ASSETS
AFS, at fair value	7,483								7,483
Fixed maturities, trading, at fair value	154,026								154,026
StarStone US | Discontinued operations, held-for-sale
ASSETS
AFS, at fair value					375,337					375,337
Fixed maturities, trading, at fair value					202,994					202,994
Equities, at fair value					3,000					3,000
Other investments, at fair value					6,389					6,389
Total investments					587,720					587,720
Cash and cash equivalents					78,613					78,613
Restricted cash and cash equivalents					5,815					5,815
Premiums receivable					99,367					99,367
Deferred tax assets					15,191					15,191
Reinsurance balances recoverable on paid and unpaid losses					530,604					530,604
Funds held by reinsured companies					35,861					35,861
Deferred acquisition costs					36,992					36,992
Goodwill and intangible assets					24,900					24,900
Other assets					59,707					59,707
TOTAL ASSETS HELD-FOR-SALE					1,474,770					1,474,770
LIABILITIES
Losses and loss adjustment expenses					836,761					836,761
Unearned premiums					218,166					218,166
Insurance and reinsurance balances payable					22,453					22,453
Other liabilities					131,151					131,151
TOTAL LIABILITIES HELD-FOR-SALE					1,208,531					1,208,531
NET ASSETS HELD-FOR-SALE					$ 266,239					266,239
Discontinued Operation, Continuing Involvement [Abstract]
Discontinued Operation, Intra-Entity Amounts, Discontinued Operation after Disposal, Revenue									11,911	10,672	98,402
Discontinued Operation, Intra-Entity Amounts, Discontinued Operation after Disposal, Income (Expense)									(16,397)	62,515	113,952
Discontinued Operation, Intra-Entity Amounts, Discontinued Operation After Disposal, Income (Loss) From Continuing Operations									28,308	(51,843)	(15,550)
StarStone US | Discontinued operations, disposed of by sale
INCOME
Net premiums earned									291,326	350,814	199,796
Net investment income									12,849	15,606	10,572
Net realized and unrealized gains									5,431	19,385	(5,352)
Other income									49	9	10
Total income									309,655	385,814	205,026
EXPENSES
Net incurred losses and loss adjustment expenses									191,844	258,396	130,303
Acquisition costs									57,640	65,342	14,935
General and administrative expenses									60,236	60,003	58,590
Interest expense									2,066	2,600	2,120
Net foreign exchange (gains) losses									(13)	33	24
Total expenses									311,773	386,374	205,972
EARNINGS (LOSS) BEFORE INCOME TAXES									(2,118)	(560)	(946)
Income tax benefit									2,255	7,935	2,435
NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES, BEFORE GAIN ON SALE									137	7,375	1,489
DISPOSAL
Consideration received	281,989								281,989			$ 235,000
Less: Carrying value of subsidiary	$ (277,697)								(277,697)
Reclassification to earnings on disposal of subsidiary									11,822
Gain on sale of subsidiary									16,114
NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES									16,251	7,375	1,489
Net loss (earnings) from discontinued operations attributable to noncontrolling interest									(8,717)	(3,025)	(611)
NET EARNINGS (LOSS) FROM DISCONTINUED OPERATIONS ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS									$ 7,534	$ 4,350	$ 878

Investments - Asset Types (Deta

Investments - Asset Types (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	$ 3,658,895,000	$ 1,666,387,000
Total investments	9,319,179,000	9,034,557,000
U.S. government and agency
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	717,998,000	381,244,000
Total investments	951,048,000	696,077,000
U.K. government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	13,574,000	15,349,000
Total investments	51,082,000	161,772,000
Other government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	150,127,000	85,147,000
Total investments	502,153,000	702,856,000
Corporate
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	1,937,349,000	880,472,000
Total investments	5,686,732,000	5,448,270,000
Municipal
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	30,032,000	3,780,000
Total investments	162,669,000	140,687,000
Residential mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	328,871,000	99,188,000
Total investments	553,945,000	400,914,000
Commercial mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	276,488,000	49,046,000
Total investments	854,090,000	813,746,000
Asset-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, available-for-sale	204,456,000	152,161,000
Total investments	557,460,000	670,235,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	458,100,000	333,300,000
Senior Secured Debt Securities
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	31,400,000
Short-term Investments
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	5,129,000	51,490,000
Debt securities, available-for-sale	263,795,000	128,335,000
Short-term Investments | U.S. government and agency
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Debt securities, available-for-sale	243,556,000	111,583,000
Short-term Investments | U.K. government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	24,411,000
Debt securities, available-for-sale	0	1,069,000
Short-term Investments | Other government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	3,424,000	21,958,000
Debt securities, available-for-sale	3,213,000	387,000
Short-term Investments | Corporate
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	1,705,000	5,121,000
Debt securities, available-for-sale	17,026,000	13,915,000
Short-term Investments | Municipal
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Debt securities, available-for-sale	0	1,381,000
Short-term Investments | Residential mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Debt securities, available-for-sale	0	0
Short-term Investments | Commercial mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Debt securities, available-for-sale	0	0
Short-term Investments | Asset-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Debt securities, available-for-sale	0	0
Fixed Maturities
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	4,594,892,000	6,143,335,000
Debt securities, available-for-sale	3,395,100,000	1,538,052,000
Fixed Maturities | U.S. government and agency
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	123,874,000	208,296,000
Debt securities, available-for-sale	474,442,000	269,661,000
Fixed Maturities | U.K. government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	37,508,000	122,012,000
Debt securities, available-for-sale	13,574,000	14,280,000
Fixed Maturities | Other government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	327,437,000	575,017,000
Debt securities, available-for-sale	146,914,000	84,760,000
Fixed Maturities | Corporate
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	3,227,726,000	3,959,288,000
Debt securities, available-for-sale	1,920,323,000	866,557,000
Fixed Maturities | Municipal
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	79,959,000	87,451,000
Debt securities, available-for-sale	30,032,000	2,399,000
Fixed Maturities | Residential mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	154,471,000	215,521,000
Debt securities, available-for-sale	328,871,000	99,188,000
Fixed Maturities | Commercial mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	347,225,000	534,357,000
Debt securities, available-for-sale	276,488,000	49,046,000
Fixed Maturities | Asset-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	296,692,000	441,393,000
Debt securities, available-for-sale	204,456,000	152,161,000
Funds Held - Directly Managed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	1,060,263,000	1,173,345,000
Funds Held - Directly Managed | U.S. government and agency
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	109,176,000	106,537,000
Funds Held - Directly Managed | U.K. government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	0	0
Funds Held - Directly Managed | Other government
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	21,165,000	20,734,000
Funds Held - Directly Managed | Corporate
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	519,952,000	603,389,000
Funds Held - Directly Managed | Municipal
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	52,678,000	49,456,000
Funds Held - Directly Managed | Residential mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	70,603,000	86,205,000
Funds Held - Directly Managed | Commercial mortgage-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	230,377,000	230,343,000
Funds Held - Directly Managed | Asset-backed
Debt and Equity Securities, FV-NI [Line Items]
Debt securities, trading	$ 56,312,000	$ 76,681,000

Investments - Contractual Matur

Investments - Contractual Maturities (Details) - Short-term investments and fixed maturities $ in Thousands	Dec. 31, 2020USD ($)
Amortized Cost
One year or less	$ 489,559
More than one year through two years	710,621
More than two years through five years	2,097,923
More than five years through ten years	1,974,838
More than ten years	1,544,533
Fixed maturity investments, at amortized cost	8,758,895
Fair Value
One year or less	494,490
More than one year through two years	726,331
More than two years through five years	2,206,020
More than five years through ten years	2,151,191
More than ten years	1,775,652
Trading securities, debt	$ 9,319,179
% of Total Fair Value
One year or less	5.30%
More than one year through two years	7.80%
More than two years through five years	23.70%
More than five years through ten years	23.10%
More than ten years	19.00%
Trading securities, percentage of fair value	100.00%
Residential mortgage-backed
Amortized Cost
Securities without single maturity date	$ 545,628
Fair Value
Securities without single maturity date	$ 553,945
% of Total Fair Value
Securities without single maturity date	5.90%
Commercial mortgage-backed
Amortized Cost
Securities without single maturity date	$ 828,155
Fair Value
Securities without single maturity date	$ 854,090
% of Total Fair Value
Securities without single maturity date	9.20%
Asset-backed
Amortized Cost
Securities without single maturity date	$ 567,638
Fair Value
Securities without single maturity date	$ 557,460
% of Total Fair Value
Securities without single maturity date	6.00%

Investments - Credit Ratings (D

Investments - Credit Ratings (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 8,758,895
Fair Value	9,319,179
Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 323,077
Marketable Securities | Portfolio Concentration Risk | Trading Securities and Available for Sale Securities
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Percent 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]
Percent of total investments	3.50%
AAA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 2,751,751
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]
Percent of total investments	29.50%
AA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,087,847
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]
Percent of total investments	11.70%
A Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 2,949,020
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]
Percent of total investments	31.60%
BBB Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 2,186,810
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]
Percent of total investments	23.50%
Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 20,674
Not Rated | Trading and Available for Sale Securities | Credit Rating Concentration Risk
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Percent of total investments	0.20%
U.S. government and agency
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 935,014
Fair Value	951,048
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]
Percent of total investments	10.20%
U.S. government and agency | AAA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 951,048
U.S. government and agency | AA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
U.S. government and agency | A Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
U.S. government and agency | BBB Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
U.S. government and agency | Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
U.K. government
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	46,988
Fair Value	51,082
U.K. government | Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 0
U.K. government | Marketable Securities | Portfolio Concentration Risk | Trading Securities and Available for Sale Securities
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Percent of total investments	0.60%
U.K. government | AAA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 0
U.K. government | AA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	43,199
U.K. government | A Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	7,883
U.K. government | BBB Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
U.K. government | Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
Other government
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	463,765
Fair Value	502,153
Other government | Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 5,267
Other government | Marketable Securities | Portfolio Concentration Risk | Trading Securities and Available for Sale Securities
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Percent of total investments	5.40%
Other government | AAA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 244,041
Other government | AA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	159,095
Other government | A Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	42,337
Other government | BBB Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	51,413
Other government | Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
Corporate
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	5,226,238
Fair Value	5,686,732
Corporate | Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 287,363
Corporate | Marketable Securities | Portfolio Concentration Risk | Trading Securities and Available for Sale Securities
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Percent of total investments	61.00%
Corporate | AAA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 172,718
Corporate | AA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	607,796
Corporate | A Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	2,646,602
Corporate | BBB Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	1,960,971
Corporate | Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	11,282
Municipal
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	145,469
Fair Value	162,669
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]
Percent of total investments	1.70%
Municipal | AAA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 8,270
Municipal | AA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	78,585
Municipal | A Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	55,631
Municipal | BBB Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	20,183
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	545,628
Fair Value	553,945
Residential mortgage-backed | Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 2,472
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]
Percent of total investments	5.90%
Residential mortgage-backed | AAA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 544,545
Residential mortgage-backed | AA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	0
Residential mortgage-backed | A Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	2,195
Residential mortgage-backed | BBB Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	2,615
Residential mortgage-backed | Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	2,118
Commercial mortgage-backed
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	828,155
Fair Value	854,090
Commercial mortgage-backed | Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 3,961
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]
Percent of total investments	9.20%
Commercial mortgage-backed | AAA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 591,396
Commercial mortgage-backed | AA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	115,114
Commercial mortgage-backed | A Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	74,615
Commercial mortgage-backed | BBB Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	61,730
Commercial mortgage-backed | Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	7,274
Asset-backed
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	567,638
Fair Value	557,460
Asset-backed | Non-Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 24,014
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]
Percent of total investments	6.00%
Asset-backed | AAA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 239,733
Asset-backed | AA Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	84,058
Asset-backed | A Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	119,757
Asset-backed | BBB Rated | Investment Grade
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	89,898
Asset-backed | Not Rated
Schedule of Trading Securities and Available-for-sale Securities [Line Items]
Amortized Cost	$ 0

Investments - Available-for-sal

Investments - Available-for-sale Portfolio (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 3,576,641	$ 1,666,126
Gross Unrealized Gains	88,514	5,608
Non-Credit Related Losses	(5,938)	(5,347)
Investments, allowance for credit losses	(322)	0
Fair Value	3,658,895	1,666,387
U.S. government and agency
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	715,527	381,488
Gross Unrealized Gains	3,305	78
Non-Credit Related Losses	(834)	(322)
Investments, allowance for credit losses	0
Fair Value	717,998	381,244
U.K. government
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	12,494	15,067
Gross Unrealized Gains	1,080	282
Non-Credit Related Losses	0	0
Investments, allowance for credit losses	0
Fair Value	13,574	15,349
Other government
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	142,459	84,116
Gross Unrealized Gains	7,721	1,119
Non-Credit Related Losses	(53)	(88)
Investments, allowance for credit losses	0	0
Fair Value	150,127	85,147
Corporate
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,873,184	880,667
Gross Unrealized Gains	65,913	3,739
Non-Credit Related Losses	(1,567)	(3,934)
Investments, allowance for credit losses	(181)	0
Fair Value	1,937,349	880,472
Municipal
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	28,881	3,770
Gross Unrealized Gains	1,155	12
Non-Credit Related Losses	(4)	(2)
Investments, allowance for credit losses	0
Fair Value	30,032	3,780
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	326,268	99,646
Gross Unrealized Gains	3,292	221
Non-Credit Related Losses	(689)	(679)
Investments, allowance for credit losses	0	0
Fair Value	328,871	99,188
Commercial mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	273,516	49,219
Gross Unrealized Gains	5,202	30
Non-Credit Related Losses	(2,097)	(203)
Investments, allowance for credit losses	(133)	0
Fair Value	276,488	49,046
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	204,312	152,153
Gross Unrealized Gains	846	127
Non-Credit Related Losses	(694)	(119)
Investments, allowance for credit losses	(8)	0
Fair Value	$ 204,456	$ 152,161

Investments - Gross Unrealized

Investments - Gross Unrealized Losses (Details) $ in Thousands	Dec. 31, 2020USD ($)Security	Dec. 31, 2019USD ($)Security
Fair Value
12 Months or Greater	$ 4,664	$ 3,962
Less Than 12 Months	527,618	760,469
Total	532,282	764,431
Gross Unrealized Losses
12 Months or Greater	(163)	(329)
Less Than 12 Months	(4,805)	(5,018)
Total	$ (4,968)	$ (5,347)
Number of securities in unrealized loss position | Security	407	479
Number of securities in unrealized loss position, twelve months or longer | Security	2	12
U.S. government and agency
Fair Value
12 Months or Greater	$ 0	$ 0
Less Than 12 Months	55,839	193,574
Total	55,839	193,574
Gross Unrealized Losses
12 Months or Greater	0	0
Less Than 12 Months	(834)	(322)
Total	(834)	(322)
UK government
Fair Value
12 Months or Greater	0
Less Than 12 Months	0
Total	0
Gross Unrealized Losses
12 Months or Greater	0
Less Than 12 Months	0
Total	0
Other government
Fair Value
12 Months or Greater	0	1,080
Less Than 12 Months	7,971	37,796
Total	7,971	38,876
Gross Unrealized Losses
12 Months or Greater	0	(23)
Less Than 12 Months	(53)	(65)
Total	(53)	(88)
Corporate
Fair Value
12 Months or Greater	0	2,754
Less Than 12 Months	199,048	338,965
Total	199,048	341,719
Gross Unrealized Losses
12 Months or Greater	0	(306)
Less Than 12 Months	(1,224)	(3,628)
Total	(1,224)	(3,934)
Municipal
Fair Value
12 Months or Greater	0	128
Less Than 12 Months	1,690	761
Total	1,690	889
Gross Unrealized Losses
12 Months or Greater	0	0
Less Than 12 Months	(4)	(2)
Total	(4)	(2)
Residential mortgage-backed
Fair Value
12 Months or Greater	4,626	0
Less Than 12 Months	79,149	52,005
Total	83,775	52,005
Gross Unrealized Losses
12 Months or Greater	(125)	0
Less Than 12 Months	(564)	(679)
Total	(689)	(679)
Commercial mortgage-backed
Fair Value
12 Months or Greater	38	0
Less Than 12 Months	67,094	35,777
Total	67,132	35,777
Gross Unrealized Losses
12 Months or Greater	(38)	0
Less Than 12 Months	(1,562)	(203)
Total	(1,600)	(203)
Asset-backed
Fair Value
12 Months or Greater	0	0
Less Than 12 Months	116,827	101,591
Total	116,827	101,591
Gross Unrealized Losses
12 Months or Greater	0	0
Less Than 12 Months	(564)	(119)
Total	$ (564)	$ (119)

Investments - Allowance for Cre

Investments - Allowance for Credit Losses (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	$ 0
Allowances for credit losses on securities for which credit losses were not previously recorded	(11,567)
Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets	0
Reductions for securities sold during the year	2,567
Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis	0
(Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period	11,737
Allowance for credit losses, end of year	(322)
Cumulative effect of change in accounting principle
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	(3,059)
Other government
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	0
Allowances for credit losses on securities for which credit losses were not previously recorded	0
Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets	0
Reductions for securities sold during the year	22
Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis	0
(Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period	0
Allowance for credit losses, end of year	0
Other government | Cumulative effect of change in accounting principle
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	(22)
Corporate
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	0
Allowances for credit losses on securities for which credit losses were not previously recorded	(10,748)
Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets	0
Reductions for securities sold during the year	2,545
Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis	0
(Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period	11,009
Allowance for credit losses, end of year	(181)
Corporate | Cumulative effect of change in accounting principle
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	(2,987)
Residential mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	0
Allowances for credit losses on securities for which credit losses were not previously recorded	(2)
Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets	0
Reductions for securities sold during the year	0
Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis	0
(Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period	2
Allowance for credit losses, end of year	0
Residential mortgage-backed | Cumulative effect of change in accounting principle
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	0
Commercial mortgage-backed
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	0
Allowances for credit losses on securities for which credit losses were not previously recorded	(675)
Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets	0
Reductions for securities sold during the year	0
Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis	0
(Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period	592
Allowance for credit losses, end of year	(133)
Commercial mortgage-backed | Cumulative effect of change in accounting principle
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	(50)
Asset-backed
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	0
Allowances for credit losses on securities for which credit losses were not previously recorded	(142)
Additions to the allowance for credit losses arising from purchases of securities accounted for as PCD assets	0
Reductions for securities sold during the year	0
Reductions in the allowance for credit losses on securities we either intend to sell or more likely than not, we will be required to sell before the recovery of their amortized cost basis	0
(Increase) decrease to the allowance for credit losses on securities that had an allowance recorded in the previous period	134
Allowance for credit losses, end of year	(8)
Asset-backed | Cumulative effect of change in accounting principle
Debt Securities, Available-for-sale [Line Items]
Allowance for credit losses, beginning of year	$ 0

Investments - Other Than Tempor

Investments - Other Than Temporary Impairment (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Other than temporary impairment losses, available-for-sale securities	$ 0	$ 0
Available-for-sale securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Credit losses	$ 0

Investments - Equity Securities

Investments - Equity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt and Equity Securities, FV-NI [Line Items]
Equity investments	$ 846,795	$ 726,721
Publicly traded equity investments
Debt and Equity Securities, FV-NI [Line Items]
Equity investments	260,767	327,875
Exchange-traded funds
Debt and Equity Securities, FV-NI [Line Items]
Equity investments	311,287	133,047
Private equity funds
Debt and Equity Securities, FV-NI [Line Items]
Equity investments	274,741	265,799
AmTrust
Debt and Equity Securities, FV-NI [Line Items]
Indirect investment	$ 230,300	$ 240,100

Investments - Other Investments

Investments - Other Investments, at Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Investments [Line Items]
Other investments, at fair value	$ 4,244,034	$ 2,518,031
Valuation lag period	3 months
Net additional subscriptions	$ 975,024	794,613	$ 900,262
Hedge funds
Other Investments [Line Items]
Other investments, at fair value	2,638,339	1,121,904
Fixed income funds
Other Investments [Line Items]
Other investments, at fair value	552,541	481,039
Private equity funds
Other Investments [Line Items]
Other investments, at fair value	363,103	323,496
Private credit funds
Other Investments [Line Items]
Other investments, at fair value	192,319	0
Equity funds
Other Investments [Line Items]
Other investments, at fair value	190,767	410,149
CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	166,523	87,509
CLO equities
Other Investments [Line Items]
Other investments, at fair value	128,083	87,555
Others
Other Investments [Line Items]
Other investments, at fair value	12,359	6,379
Other investments
Other Investments [Line Items]
Unrealized gains	1,336,343	441,702	$ (164,455)
Net additional subscriptions		380,300
Unfunded commitments	975,500
Less than 1 Year
Other Investments [Line Items]
Other investments, at fair value	3,540,382
Less than 1 Year | Hedge funds
Other Investments [Line Items]
Other investments, at fair value	2,590,164
Less than 1 Year | Fixed income funds
Other Investments [Line Items]
Other investments, at fair value	537,055
Less than 1 Year | Private equity funds
Other Investments [Line Items]
Other investments, at fair value	0
Less than 1 Year | Private credit funds
Other Investments [Line Items]
Other investments, at fair value	0
Less than 1 Year | Equity funds
Other Investments [Line Items]
Other investments, at fair value	190,767
Less than 1 Year | CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	94,313
Less than 1 Year | CLO equities
Other Investments [Line Items]
Other investments, at fair value	128,083
Less than 1 Year | Others
Other Investments [Line Items]
Other investments, at fair value
1-2 years
Other Investments [Line Items]
Other investments, at fair value	70,991
1-2 years | Hedge funds
Other Investments [Line Items]
Other investments, at fair value	0
1-2 years | Fixed income funds
Other Investments [Line Items]
Other investments, at fair value	0
1-2 years | Private equity funds
Other Investments [Line Items]
Other investments, at fair value	0
1-2 years | Private credit funds
Other Investments [Line Items]
Other investments, at fair value	9,250
1-2 years | Equity funds
Other Investments [Line Items]
Other investments, at fair value	0
1-2 years | CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	61,741
1-2 years | CLO equities
Other Investments [Line Items]
Other investments, at fair value	0
1-2 years | Others
Other Investments [Line Items]
Other investments, at fair value
2-3 years
Other Investments [Line Items]
Other investments, at fair value	10,469
2-3 years | Hedge funds
Other Investments [Line Items]
Other investments, at fair value	0
2-3 years | Fixed income funds
Other Investments [Line Items]
Other investments, at fair value	0
2-3 years | Private equity funds
Other Investments [Line Items]
Other investments, at fair value	0
2-3 years | Private credit funds
Other Investments [Line Items]
Other investments, at fair value
2-3 years | Equity funds
Other Investments [Line Items]
Other investments, at fair value	0
2-3 years | CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	10,469
2-3 years | CLO equities
Other Investments [Line Items]
Other investments, at fair value	0
2-3 years | Others
Other Investments [Line Items]
Other investments, at fair value
More than 3 years
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years | Hedge funds
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years | Fixed income funds
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years | Private equity funds
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years | Private credit funds
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years | Equity funds
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years | CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years | CLO equities
Other Investments [Line Items]
Other investments, at fair value	0
More than 3 years | Others
Other Investments [Line Items]
Other investments, at fair value
Not Eligible/ Restricted
Other Investments [Line Items]
Other investments, at fair value	622,192
Not Eligible/ Restricted | Hedge funds
Other Investments [Line Items]
Other investments, at fair value	48,175	$ 51,800
Not Eligible/ Restricted | Fixed income funds
Other Investments [Line Items]
Other investments, at fair value	15,486
Not Eligible/ Restricted | Private equity funds
Other Investments [Line Items]
Other investments, at fair value	363,103
Not Eligible/ Restricted | Private credit funds
Other Investments [Line Items]
Other investments, at fair value	183,069
Not Eligible/ Restricted | Equity funds
Other Investments [Line Items]
Other investments, at fair value	0
Not Eligible/ Restricted | CLO equity funds
Other Investments [Line Items]
Other investments, at fair value	0
Not Eligible/ Restricted | CLO equities
Other Investments [Line Items]
Other investments, at fair value	0
Not Eligible/ Restricted | Others
Other Investments [Line Items]
Other investments, at fair value	$ 12,359

Investments - Equity Method Inv

Investments - Equity Method Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Ownership %	47.40%	47.40%
Equity method investments	$ 832,295	$ 326,277
Citco | CTCO Holdings Limited
Schedule of Equity Method Investments [Line Items]
Ownership interest held by noncontrolling owners	6.20%
Convertible Preferred Stock | Citco | CTCO Holdings Limited
Schedule of Equity Method Investments [Line Items]
Ownership interest held by noncontrolling owners	15.40%
Enhanzed Re
Schedule of Equity Method Investments [Line Items]
Ownership %	47.40%	47.40%
Equity method investments	$ 330,289	$ 182,856
Citco
Schedule of Equity Method Investments [Line Items]
Ownership %		31.90%
Equity method investments	$ 53,022	$ 51,742
Citco | Ordinary Shares
Schedule of Equity Method Investments [Line Items]
Ownership %	31.90%
Monument Re
Schedule of Equity Method Investments [Line Items]
Ownership %	23.00%	23.50%
Equity method investments	$ 193,716	$ 60,598
Monument Re | Ordinary Shares
Schedule of Equity Method Investments [Line Items]
Ownership %	20.00%	20.00%
Clear Spring
Schedule of Equity Method Investments [Line Items]
Ownership %	0.00%	20.00%
Equity method investments	$ 0	$ 10,645
StarStone US
Schedule of Equity Method Investments [Line Items]
Ownership %	25.20%	0.00%
Equity method investments	$ 235,000	$ 0
Other
Schedule of Equity Method Investments [Line Items]
Ownership %	27.00%	30.00%
Equity method investments	$ 20,268	$ 20,436
Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Unfunded commitments	$ 68,700

Investments - Funds Held (Detai

Investments - Funds Held (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Funds Held, Directly Managed [Abstract]
Funds held - directly managed	$ 1,074,890	$ 1,187,552
Net unrealized gains (losses):
Funds held by reinsured companies	635,819	475,732
AXA Group
Net unrealized gains (losses):
Reinsurance premium consideration	204,200
Funds Held - Directly Managed
Funds Held, Directly Managed [Abstract]
Fixed maturity investments, trading	1,060,263	1,173,345
Cash and cash equivalents	9,067	10,296
Other assets	5,560	3,911
Funds held - directly managed	1,074,890	1,187,552
Funds Held, Directly Managed, Fixed-Maturity Investment Components [Abstract]
Fixed maturity investments, at amortized cost	966,341	1,126,053
Net unrealized gains (losses):
Change in fair value - fair value option accounting	9,693	5,438
Change in fair value - embedded derivative accounting	84,229	41,854
Fixed maturity investments, trading	1,060,263	1,173,345
Funds held - Directly Managed - Fair Value Option
Funds Held, Directly Managed [Abstract]
Fixed maturity investments, trading	116,631	191,297
Funds Held, Directly Managed, Fixed-Maturity Investment Components [Abstract]
Fixed maturity investments, at amortized cost	106,938	185,859
Net unrealized gains (losses):
Change in fair value - fair value option accounting	9,693	5,438
Change in fair value - embedded derivative accounting	0	0
Fixed maturity investments, trading	116,631	191,297
Funds held - Directly Managed - Variable Return
Funds Held, Directly Managed [Abstract]
Fixed maturity investments, trading	943,632	982,048
Funds Held, Directly Managed, Fixed-Maturity Investment Components [Abstract]
Fixed maturity investments, at amortized cost	859,403	940,194
Net unrealized gains (losses):
Change in fair value - fair value option accounting	0	0
Change in fair value - embedded derivative accounting	84,229	41,854
Fixed maturity investments, trading	$ 943,632	$ 982,048

Investments - Net Investment In

Investments - Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Investment Income [Line Items]
Gross investment income									$ 318,707	$ 322,711	$ 270,779
Investment expenses									(15,890)	(14,440)	(9,081)
Net investment income	$ 61,530	$ 72,130	$ 94,443	$ 74,714	$ 76,847	$ 81,502	$ 74,271	$ 75,651	302,817	308,271	261,698
Fixed maturity investments, trading
Net Investment Income [Line Items]
Gross investment income									198,988	217,886	178,213
Short-term investments and cash and cash equivalents
Net Investment Income [Line Items]
Gross investment income									4,843	15,609	11,692
Funds held
Net Investment Income [Line Items]
Gross investment income									33,920	22,580	11,640
Funds held – directly managed
Net Investment Income [Line Items]
Gross investment income									34,563	38,173	37,623
Investment income from fixed maturities and cash and cash equivalents
Net Investment Income [Line Items]
Gross investment income									272,314	294,248	239,168
Equity investments
Net Investment Income [Line Items]
Gross investment income									19,240	16,671	5,397
Other investments
Net Investment Income [Line Items]
Gross investment income									27,153	11,792	26,214
Investment income from equities and other investments
Net Investment Income [Line Items]
Gross investment income									$ 46,393	$ 28,463	$ 31,611

Investments - Net Realized and

Investments - Net Realized and Unrealized Gains (Losses) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, AFS									$ 26,313	$ 4,844	$ 27
Gross realized losses on fixed maturity securities, AFS									(7,801)	(905)	(90)
Decrease in allowance for expected credit losses on fixed maturity securities, AFS									(509)	0	0
Net realized investment gains on investment derivatives									144	0	0
Total net realized gains (losses) on sale									178,851	86,071	(27,395)
Net unrealized gains (losses):
Investment derivatives									718	(349)	0
Total net unrealized gains (losses)									1,463,168	925,895	(380,137)
Net realized and unrealized gains (losses)	$ 803,467	$ 500,005	$ 967,608	$ (629,061)	$ 153,477	$ 145,060	$ 260,669	$ 452,760	1,642,019	1,011,966	(407,532)
Proceeds from sale of available from sale securities									2,000,000	302,900	11,400
Fixed maturity investments
Net realized gains (losses) on sale:
Gross realized gains on fixed maturity securities, AFS									26,313	4,844	27
Gross realized losses on fixed maturity securities, AFS									(7,801)	(905)	(90)
Decrease in allowance for expected credit losses on fixed maturity securities, AFS									170	0	0
Net realized gains (losses) on trading securities									126,945	81,011	(27,408)
Net unrealized gains (losses):
Fixed maturity securities, trading									101,022	341,130
Fixed maturity securities, trading											(159,594)
Funds Held - Directly Managed
Net realized gains (losses) on sale:
Net realized gains (losses) on trading securities									8,798	1,495	(3,940)
Net unrealized gains (losses):
Fixed maturity securities, trading									50,837	88,053
Fixed maturity securities, trading											(46,257)
Equity investments
Net realized gains (losses) on sale:
Net realized gains (losses) on equity investments									24,282	(374)	4,016
Net unrealized gains (losses):
Equity investments									(25,752)	55,359	(9,831)
Other investments
Net unrealized gains (losses):
Other investments									1,336,343	$ 441,702	$ (164,455)
Other investments | Hedge Fund Managed By AnglePoint
Net unrealized gains (losses):
Total net unrealized gains (losses)									$ 1,200,000

Investments - Reconciliation to

Investments - Reconciliation to Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Gross realized gains on fixed maturity securities, AFS	$ 26,313	$ 4,844	$ 27
Gross realized losses on fixed maturity securities, AFS	(7,801)	(905)	(90)
Tax effect	(1,623)	0	0
Total reclassification adjustment for net realized gains (losses) included in net earnings	18,033	3,894	(63)
Credit recoveries (losses) on fixed maturity securities, AFS	509	0	0
Discontinued Operations
Debt Securities, Available-for-sale [Line Items]
Gross realized gains on fixed maturity securities, AFS	1,374	12	0
Gross realized losses on fixed maturity securities, AFS	(120)	(57)	0
Tax effect	(110)	0	0
Credit recoveries (losses) on fixed maturity securities, AFS	329	0	0
Tax effect	7	0	0
Continuing Operations
Debt Securities, Available-for-sale [Line Items]
Credit recoveries (losses) on fixed maturity securities, AFS	170	0	0
Tax effect	$ 3	$ 0	$ 0

Investments - Restricted Assets

Investments - Restricted Assets (Details) $ in Thousands	Dec. 31, 2020USD ($)syndicate	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Investments, Debt and Equity Securities [Abstract]
Restricted cash and cash equivalents	$ 471,964	$ 346,877	$ 366,187
Line of Credit Facility [Line Items]
Collateral in trust for third party agreements	4,924,866	4,103,847
Assets on deposit with regulatory authorities	131,283	309,659
Funds at Lloyd's	260,914	639,316
Restricted assets, total	$ 5,421,690	5,185,492
Number of syndicates | syndicate	3
Asset Pledged as Collateral
Line of Credit Facility [Line Items]
Collateral for secured letter of credit facilities	$ 104,627	$ 132,670

Derivatives and Hedging Instr_3

Derivatives and Hedging Instruments - Foreign Currency Hedging (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effect of Net Investment Hedge
Cumulative currency translation adjustment	$ (2,069)	$ (2,428)	$ (202)
Net Investment Hedging
Effect of Net Investment Hedge
Cumulative currency translation adjustment			3,100
Designated as Hedging Instrument | Currency forward contracts
Gross Notional Amounts and Estimated Fair Values
Gross Notional Amount	603,691	495,291
Assets	1,169	642
Liabilities	28,947	11,452
Effect of Net Investment Hedge
Amount of Gains (Losses) Deferred in AOCI	(30,275)	(15,328)	4,438
Designated as Hedging Instrument | Currency forward contracts | Australia, Dollars
Gross Notional Amounts and Estimated Fair Values
Gross Notional Amount	73,852	64,620
Assets	13	52
Liabilities	5,060	2,033
Effect of Net Investment Hedge
Amount of Gains (Losses) Deferred in AOCI	(6,792)	(722)	3,438
Designated as Hedging Instrument | Currency forward contracts | Euro Member Countries, Euro
Gross Notional Amounts and Estimated Fair Values
Gross Notional Amount	217,168	112,284
Assets	205	246
Liabilities	8,889	1,635
Effect of Net Investment Hedge
Amount of Gains (Losses) Deferred in AOCI	(15,026)	1,817	1,000
Designated as Hedging Instrument | Currency forward contracts | United Kingdom, Pounds
Gross Notional Amounts and Estimated Fair Values
Gross Notional Amount	312,671	318,387
Assets	951	344
Liabilities	14,998	7,784
Effect of Net Investment Hedge
Amount of Gains (Losses) Deferred in AOCI	$ (8,457)	$ (16,423)	$ 0

Derivatives and Hedging Instr_4

Derivatives and Hedging Instruments - Foreign Currency Forward Contracts (Details) - Not Designated as Hedging Instrument - Currency forward contracts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Gross Notional Amount	$ 139,334	$ 153,563
Assets	2,835	1,369
Liabilities	5,056	4,106
Gains (losses) on non-qualifying hedges charged to earnings	(2,954)	13,207	$ 31,643
Australia, Dollars
Derivative [Line Items]
Gross Notional Amount	28,848	913
Assets	882	839
Liabilities	2,847	892
Gains (losses) on non-qualifying hedges charged to earnings	(2,388)	1,523	4,958
Canada, Dollars
Derivative [Line Items]
Gross Notional Amount	64,224	66,266
Assets	10	10
Liabilities	1,764	1,482
Gains (losses) on non-qualifying hedges charged to earnings	(879)	(2,079)	9,311
Euro Member Countries, Euro
Derivative [Line Items]
Gross Notional Amount	43,531	74,444
Assets	1,782	507
Liabilities	41	1,440
Gains (losses) on non-qualifying hedges charged to earnings	1,871	1,759	2,296
United Kingdom, Pounds
Derivative [Line Items]
Gross Notional Amount	2,731	11,940
Assets	161	13
Liabilities	404	292
Gains (losses) on non-qualifying hedges charged to earnings	$ (1,558)	$ 12,004	$ 15,078

Derivatives and Hedging Instr_5

Derivatives and Hedging Instruments - Investments in Call Options (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Unrealized gains (losses) in net earnings (less than)	$ 718	$ (349)	$ 0
Not Designated as Hedging Instrument | Call options on equity
Derivative [Line Items]
Unrealized gains (losses) in net earnings (less than)	$ (100)	500	(9,400)
Gross Notional Amount			$ 10,000
Fair value (less than)		$ 100

Derivatives and Hedging Instr_6

Derivatives and Hedging Instruments - Forward Interest Rate Swaps (Details) $ in Thousands, $ in Millions	12 Months Ended			15 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Apr. 07, 2020USD ($)	Dec. 31, 2019AUD ($)
Derivative [Line Items]
Unrealized gains (losses) in net earnings	$ 718	$ (349)	$ 0
Interest Rate Swap
Derivative [Line Items]
Notional amount					$ 120
Unrealized gains (losses) in net earnings	$ 800
Realized gain				$ 500
Carrying value | Interest Rate Swap
Derivative [Line Items]
Derivative instruments		$ 300

Derivatives and Hedging Instr_7

Derivatives and Hedging Instruments - Credit Default Swaps, Futures and Currency Forward Contracts (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Derivative [Line Items]
Net gains (losses)	$ 626
Credit default swaps
Derivative [Line Items]
Net gains (losses)	181
Futures contracts
Derivative [Line Items]
Net gains (losses)	(127)
Futures contracts | Long positions
Derivative [Line Items]
Gross Notional Amount	34,502
Assets	32
Liabilities	5
Futures contracts | Short positions
Derivative [Line Items]
Gross Notional Amount	(32,316)
Assets	6
Liabilities	121
Currency forward contracts
Derivative [Line Items]
Net gains (losses)	572
Currency forward contracts | Long positions | United States of America, Dollars
Derivative [Line Items]
Gross Notional Amount	1,428
Assets	0
Liabilities	13
Currency forward contracts | Long positions | United Kingdom, Pounds
Derivative [Line Items]
Gross Notional Amount	1,278
Assets	19
Liabilities	0
Currency forward contracts | Short positions | United States of America, Dollars
Derivative [Line Items]
Gross Notional Amount	(3,233)
Assets	60
Liabilities	0
Currency forward contracts | Short positions | United Kingdom, Pounds
Derivative [Line Items]
Gross Notional Amount	(4,418)
Assets	12
Liabilities	0
Credit default swaps, futures contracts and currency forward contracts
Derivative [Line Items]
Gross Notional Amount	(2,759)
Assets	129
Liabilities	$ 139

Reinsurance Balances Recovera_3

Reinsurance Balances Recoverable on Paid and Unpaid Losses - Summary of Reinsurance Reserves Recoverable (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effects of Reinsurance [Line Items]
Outstanding losses	$ 1,201,869	$ 1,245,435
IBNR	647,843	785,530
ULAE	16,688
Fair value adjustments - acquired companies	(15,353)	(15,255)
Fair value adjustments - fair value option	(21,427)	(88,086)
Total reinsurance reserves recoverable	1,829,620	1,927,624	$ 1,708,272	$ 1,693,028
Paid losses recoverable	259,543	253,510
Total	2,089,163	2,181,134
Reinsurance balances recoverable on paid and unpaid losses	1,568,333	1,485,616
Reinsurance balances recoverable on paid and unpaid losses - fair value option	520,830	695,518
Non-life Run-off
Effects of Reinsurance [Line Items]
Outstanding losses	938,231	972,293
IBNR	508,082	673,059
ULAE	16,688
Fair value adjustments - acquired companies	(14,014)	(13,652)
Fair value adjustments - fair value option	(21,427)	(88,086)
Total reinsurance reserves recoverable	1,427,560	1,543,614	1,366,123	1,377,485
Paid losses recoverable	172,309	181,375
Total	1,599,869	1,724,989
Reinsurance balances recoverable on paid and unpaid losses	1,079,039	1,029,471
Reinsurance balances recoverable on paid and unpaid losses - fair value option	520,830	695,518
Atrium
Effects of Reinsurance [Line Items]
Outstanding losses		9,011
IBNR		19,286
Fair value adjustments - acquired companies		519
Fair value adjustments - fair value option		0
Total reinsurance reserves recoverable	0	28,816	38,768	40,531
Paid losses recoverable		1,541
Total		30,357
Reinsurance balances recoverable on paid and unpaid losses		30,357
Reinsurance balances recoverable on paid and unpaid losses - fair value option		0
StarStone
Effects of Reinsurance [Line Items]
Outstanding losses	263,638	264,131
IBNR	139,761	93,185
ULAE	0
Fair value adjustments - acquired companies	(1,339)	(2,122)
Fair value adjustments - fair value option	0	0
Total reinsurance reserves recoverable	402,060	355,194	$ 303,381	$ 275,012
Paid losses recoverable	87,234	70,594
Total	489,294	425,788
Reinsurance balances recoverable on paid and unpaid losses	489,294	425,788
Reinsurance balances recoverable on paid and unpaid losses - fair value option	$ 0	$ 0

Reinsurance Balances Recovera_4

Reinsurance Balances Recoverable on Paid and Unpaid Losses - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effects of Reinsurance [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 2,089,163	$ 2,181,134
(Decrease) in reinsurance recoverable	(52,027)	$ 316,440	$ 289,295
Non-Life Run-Off
Effects of Reinsurance [Line Items]
(Decrease) in reinsurance recoverable	$ (92,000)

Reinsurance Balances Recovera_5

Reinsurance Balances Recoverable on Paid and Unpaid Losses - Top Ten Reinsurers (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)reinsurer	Dec. 31, 2019USD ($)reinsurer
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 2,089,163	$ 2,181,134
Reinsurer concentration risk | Top 10 reinsurers
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	1,364,593	1,471,604
Reinsurance balances recoverable | Reinsurer concentration risk
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 2,089,163	$ 2,181,134
% of Total	100.00%	100.00%
Reinsurance balances recoverable | Reinsurer concentration risk | Top Ten Reinsurers, Rated A Minus Or Higher
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 863,819	$ 1,199,479
Number of external reinsurers | reinsurer	7	8
Reinsurance balances recoverable | Reinsurer concentration risk | Top Ten Reinsurers, Non-Rated Reinsurers
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 500,774	$ 272,125
Number of external reinsurers | reinsurer	3	2
Reinsurance balances recoverable | Reinsurer concentration risk | Top 10 reinsurers
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 1,364,593	$ 1,471,604
% of Total	65.30%	67.40%
Reinsurance balances recoverable | Reinsurer concentration risk | Other Reinsurers' Balances Greater Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 697,602	$ 688,732
% of Total	33.40%	31.60%
Reinsurance balances recoverable | Reinsurer concentration risk | Other Reinsurers' Balances Less Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 26,968	$ 20,798
% of Total	1.30%	1.00%
Reinsurance balances recoverable | Reinsurer concentration risk | Top Ten Reinsurers, Non-Rated Reinsurers, US State Backed
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 229,400	$ 190,800
Reinsurance balances recoverable | Reinsurer concentration risk | Top Ten Reinsurers, Non-Rated Reinsurers, Provided Security
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	73,800	81,400
Reinsurance balances recoverable | Reinsurer concentration risk | Top Ten Reinsurers, Non-Rated Reinsurers, Provided Security, Reinsurer Two
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	208,400
Non-life Run-off
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	1,599,869	1,724,989
Non-life Run-off | Reinsurance balances recoverable | Reinsurer concentration risk
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	1,599,869	1,724,989
Non-life Run-off | Reinsurance balances recoverable | Reinsurer concentration risk | Top 10 reinsurers
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	1,036,676	1,154,110
Non-life Run-off | Reinsurance balances recoverable | Reinsurer concentration risk | Other Reinsurers' Balances Greater Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	539,428	551,636
Non-life Run-off | Reinsurance balances recoverable | Reinsurer concentration risk | Other Reinsurers' Balances Less Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	23,765	19,243
Atrium
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses		30,357
Atrium | Reinsurance balances recoverable | Reinsurer concentration risk
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses		30,357
Atrium | Reinsurance balances recoverable | Reinsurer concentration risk | Top 10 reinsurers
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses		22,051
Atrium | Reinsurance balances recoverable | Reinsurer concentration risk | Other Reinsurers' Balances Greater Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses		7,761
Atrium | Reinsurance balances recoverable | Reinsurer concentration risk | Other Reinsurers' Balances Less Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses		545
StarStone
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	489,294	425,788
StarStone | Reinsurance balances recoverable | Reinsurer concentration risk
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	489,294	425,788
StarStone | Reinsurance balances recoverable | Reinsurer concentration risk | Top 10 reinsurers
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	327,917	295,443
StarStone | Reinsurance balances recoverable | Reinsurer concentration risk | Other Reinsurers' Balances Greater Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	158,174	129,335
StarStone | Reinsurance balances recoverable | Reinsurer concentration risk | Other Reinsurers' Balances Less Than $1 Million
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	3,203	1,010
Equity method investee | Reinsurer concentration risk | Hannover Ruck SE
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	0	259,077
Equity method investee | Reinsurer concentration risk | Lloyd's Syndicate
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	331,118	396,246
Equity method investee | Reinsurer concentration risk | Michigan Catastrophic Claims Associations
Ceded Credit Risk [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	$ 229,374	$ 0

Reinsurance Balances Recovera_6

Reinsurance Balances Recoverable on Paid and Unpaid Losses - Provisions for Uncollectible Reinsurance Balances Recoverable by Rating of Reinsurer (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effects of Reinsurance [Line Items]
Gross	$ 2,226,285	$ 2,328,773
Allowance for estimated uncollectible reinsurance	137,122	147,639	$ 156,732
Total	$ 2,089,163	$ 2,181,134
Provisions as a % of Gross	6.20%	6.30%
Reinsurers rated A- or above
Effects of Reinsurance [Line Items]
Gross	$ 1,464,529	$ 1,731,270
Allowance for estimated uncollectible reinsurance	60,801	43,427
Total	$ 1,403,728	$ 1,687,843
Provisions as a % of Gross	4.20%	2.50%
Secured | Reinsurers Rated Below A-
Effects of Reinsurance [Line Items]
Gross	$ 608,999	$ 463,840
Allowance for estimated uncollectible reinsurance	0	0
Total	$ 608,999	$ 463,840
Provisions as a % of Gross	0.00%	0.00%
Unsecured | Reinsurers Rated Below A-
Effects of Reinsurance [Line Items]
Gross	$ 152,757	$ 133,663
Allowance for estimated uncollectible reinsurance	76,321	104,212
Total	$ 76,436	$ 29,451
Provisions as a % of Gross	50.00%	78.00%

Reinsurance Balances Recovera_7

Reinsurance Balances Recoverable on Paid and Unpaid Losses - Allowance For Credit Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Allowance for estimated uncollectible reinsurance, beginning of year	$ 147,639	$ 156,732
Effect of exchange rate movement	700	(887)
Current period change in the allowance	(381)	2,077
Write-offs charged against the allowance	(9,625)	(9,871)
Recoveries collected	(1,016)	(412)
Allowance for estimated uncollectible reinsurance, end of year	137,122	147,639
Cumulative effect of change in accounting principle
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Allowance for estimated uncollectible reinsurance, beginning of year	$ (195)	0
Allowance for estimated uncollectible reinsurance, end of year		$ (195)

Deferred Charge Assets and De_3

Deferred Charge Assets and Deferred Gain Liabilities (Deferred Charge Assets) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Beginning carrying value	$ 272,462,000	$ 86,585,000	$ 80,192,000
Recorded during the year	11,746,000	224,504,000	20,174,000
Amortization	(45,606,000)	(38,627,000)	(13,781,000)
Ending carrying value	238,602,000	$ 272,462,000	$ 86,585,000
Impairment	$ 0

Deferred Charge Assets and De_4

Deferred Charge Assets and Deferred Gain Liabilities (Deferred Gain Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Movement Analysis Of Deferred Gain Liabilities [Roll Forward]
Beginning carrying value	$ 12,875	$ 0
Recorded during the year	9,365	13,758
Amortization	(2,360)	(883)
Ending carrying value	$ 19,880	$ 12,875

Losses and Loss Adjustment Ex_3

Losses and Loss Adjustment Expenses - Total Losses and Loss Adjustment Expense Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	$ 5,127,849	$ 5,249,565
IBNR	5,277,503	4,651,649
Fair value adjustments - acquired companies	(143,183)	(167,511)
Fair value adjustments - fair value option	(54,589)	(217,933)
ULAE	385,702	352,634
Total	10,593,282	9,868,404	$ 9,048,796	$ 7,100,488
Loss and loss adjustment expenses	8,140,362	7,247,282
Loss and loss adjustment expenses, at fair value	2,452,920	2,621,122
Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	4,440,425	4,407,082
IBNR	4,641,500	3,945,407
Fair value adjustments - acquired companies	(142,854)	(170,689)
Fair value adjustments - fair value option	(54,589)	(217,933)
ULAE	333,913	331,494
Total	9,235,082	8,295,361	7,540,662	5,949,472
Atrium
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses		89,141
IBNR		136,543
Fair value adjustments - acquired companies		3,700
ULAE		2,288
Total	0	231,672	241,284	240,873
StarStone
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	677,220	743,830
IBNR	615,963	556,134
Fair value adjustments - acquired companies	(329)	(522)
ULAE	35,101	18,852
Total	1,327,956	1,318,294	$ 1,247,989	$ 910,143
Operating Segments | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	4,440,425	4,407,082
IBNR	4,641,500	3,945,407
Fair value adjustments - acquired companies	(142,854)	(170,689)
Fair value adjustments - fair value option	(54,589)	(217,933)
ULAE	350,600	331,494
Total	9,235,082	8,295,361
Loss and loss adjustment expenses	6,782,162	5,674,239
Loss and loss adjustment expenses, at fair value	2,452,920	2,621,122
Operating Segments | Atrium
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses		89,141
IBNR		136,543
Fair value adjustments - acquired companies		3,700
Fair value adjustments - fair value option		0
ULAE		2,288
Total		231,672
Loss and loss adjustment expenses		231,672
Loss and loss adjustment expenses, at fair value		0
Operating Segments | StarStone
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	677,220	743,830
IBNR	615,963	556,134
Fair value adjustments - acquired companies	(329)	(522)
Fair value adjustments - fair value option	0	0
ULAE	35,102	18,852
Total	1,327,956	1,318,294
Loss and loss adjustment expenses	1,327,956	1,318,294
Loss and loss adjustment expenses, at fair value	0	0
Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Outstanding losses	10,204	9,512
IBNR	20,040	13,565
Fair value adjustments - acquired companies	0	0
Fair value adjustments - fair value option	0	0
ULAE	0	0
Total	30,244	23,077
Loss and loss adjustment expenses	30,244	23,077
Loss and loss adjustment expenses, at fair value	$ 0	$ 0

Losses and Loss Adjustment Ex_4

Losses and Loss Adjustment Expenses - Reconciliation of Beginning and Ending Reserves for Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as of January 1				$ 9,868,404				$ 9,048,796	$ 9,868,404	$ 9,048,796	$ 7,100,488
Less: reinsurance reserves recoverable				1,927,624				1,708,272	1,927,624	1,708,272	1,693,028
Less: net deferred charge assets and gain liabilities on retroactive reinsurance				259,587				86,585	259,587	86,585	80,192
Net balance as of January 1				7,681,193				7,253,939	7,681,193	7,253,939
Net incurred losses and LAE:
Current period									405,178	580,074	533,081
Prior periods									10,748	34,105	(209,359)
Total net incurred losses and LAE	$ 76,248	$ 109,686	$ 186,692	43,300	$ 48,068	$ 163,258	$ 146,554	256,299	415,926	614,179	323,722
Net paid losses:
Current period									(71,989)	(179,461)	(176,172)
Prior periods									(1,413,500)	(1,609,009)	(1,158,614)
Total net paid losses									(1,485,489)	(1,788,470)	(1,334,786)
Effect of exchange rate movement									119,663	47,812	(145,243)
Acquired on purchase of subsidiaries									0	686	1,310,874
Assumed business									2,186,024	1,586,307	1,772,104
Ceded business									(154,926)	(33,260)	0
Reclassification to assets and liabilities held-for-sale									(216,808)	0	0
Net balance as of December 31	8,544,940				7,681,193				8,544,940	7,681,193	7,253,939
Plus: reinsurance reserves recoverable	1,829,620				1,927,624				1,829,620	1,927,624	1,708,272
Plus: net deferred charge assets and gain liabilities on retroactive reinsurance	218,722				259,587				218,722	259,587	86,585
Balance as of December 31	10,593,282				9,868,404				10,593,282	9,868,404	9,048,796
Cumulative effect of change in accounting principle
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances					643					643	0	$ 0
Cumulative effect of change in accounting principle | Discontinued operations, held-for-sale | StarStone US
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances					400					400
Cumulative effect of change in accounting principle, adjusted balance
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net balance as of January 1				7,680,550				7,253,939	7,680,550	7,253,939	5,327,268
Net paid losses:
Net balance as of December 31					7,680,550					7,680,550	7,253,939
Non-life Run-off
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as of January 1				8,295,361				7,540,662	8,295,361	7,540,662	5,949,472
Less: reinsurance reserves recoverable				1,543,614				1,366,123	1,543,614	1,366,123	1,377,485
Less: net deferred charge assets and gain liabilities on retroactive reinsurance				259,587				86,585	259,587	86,585	80,192
Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances	(48,443)								(48,443)
Net balance as of January 1				6,492,160				6,087,954	6,492,160	6,087,954
Net incurred losses and LAE:
Current period									30,165	123,559	12,451
Prior periods									14,830	(71,934)	(318,518)
Total net incurred losses and LAE									44,995	51,625	(306,067)
Net paid losses:
Current period									(9,990)	(64,820)	(5)
Prior periods									(1,064,911)	(1,182,804)	(838,812)
Total net paid losses									(1,074,901)	(1,247,624)	(838,817)
Effect of exchange rate movement									94,745	46,472	(132,632)
Acquired on purchase of subsidiaries									0	686	1,111,839
Assumed business									2,186,024	1,586,307	1,761,836
Ceded business									(154,926)	(33,260)	0
Net balance as of December 31	7,588,800				6,492,160				7,588,800	6,492,160	6,087,954
Plus: reinsurance reserves recoverable	1,427,560				1,543,614				1,427,560	1,543,614	1,366,123
Plus: net deferred charge assets and gain liabilities on retroactive reinsurance	218,722				259,587				218,722	259,587	86,585
Balance as of December 31	9,235,082				8,295,361				9,235,082	8,295,361	7,540,662
Non-life Run-off | Cumulative effect of change in accounting principle
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances					703					703	0	0
Non-life Run-off | Cumulative effect of change in accounting principle, adjusted balance
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net balance as of January 1				6,492,863				6,087,954	6,492,863	6,087,954	4,491,795
Net paid losses:
Net balance as of December 31					6,492,863					6,492,863	6,087,954
Atrium
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as of January 1				231,672				241,284	231,672	241,284	240,873
Less: reinsurance reserves recoverable				28,816				38,768	28,816	38,768	40,531
Net balance as of January 1				202,856				202,516	202,856	202,516
Net incurred losses and LAE:
Current period									93,471	85,027	83,627
Prior periods									(6,245)	(7,751)	(13,817)
Total net incurred losses and LAE									87,226	77,276	69,810
Net paid losses:
Current period									(33,724)	(34,617)	(35,537)
Prior periods									(40,196)	(43,572)	(28,969)
Total net paid losses									(73,920)	(78,189)	(64,506)
Effect of exchange rate movement									1,497	1,253	(3,130)
Reclassification to assets and liabilities held-for-sale									(216,808)	0	0
Net balance as of December 31	0				202,856				0	202,856	202,516
Plus: reinsurance reserves recoverable	0				28,816				0	28,816	38,768
Balance as of December 31	0				231,672				0	231,672	241,284
Atrium | Cumulative effect of change in accounting principle
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances					851					851	0	0
Atrium | Cumulative effect of change in accounting principle, adjusted balance
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net balance as of January 1				202,005				202,516	202,005	202,516	200,342
Net paid losses:
Net balance as of December 31					202,005					202,005	202,516
StarStone
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Balance as of January 1				1,318,294				1,247,989	1,318,294	1,247,989	910,143
Less: reinsurance reserves recoverable				355,194				303,381	355,194	303,381	275,012
Net balance as of January 1				963,100				944,608	963,100	944,608
Net incurred losses and LAE:
Current period									263,562	354,884	422,191
Prior periods									3,176	114,356	120,889
Total net incurred losses and LAE									266,738	469,240	543,080
Net paid losses:
Current period									(26,831)	(75,458)	(137,390)
Prior periods									(300,037)	(375,377)	(289,981)
Total net paid losses									(326,868)	(450,835)	(427,371)
Effect of exchange rate movement									23,421	87	(9,481)
Acquired on purchase of subsidiaries									0	0	192,981
Assumed business									0	0	10,268
Ceded business									0	0	0
Net balance as of December 31	925,896				963,100				925,896	963,100	944,608
Plus: reinsurance reserves recoverable	402,060				355,194				402,060	355,194	303,381
Balance as of December 31	$ 1,327,956				1,318,294				1,327,956	1,318,294	1,247,989
StarStone | Cumulative effect of change in accounting principle
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Less: cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible reinsurance balances					495					495	0	$ 0
StarStone | Cumulative effect of change in accounting principle, adjusted balance
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net balance as of January 1				$ 962,605				$ 944,608	$ 962,605	944,608	635,131
Net paid losses:
Net balance as of December 31					$ 962,605					$ 962,605	$ 944,608

Losses and Loss Adjustment Ex_5

Losses and Loss Adjustment Expenses - Net Incurred Losses and Loss Adjustment Expense Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Prior Period
Net losses paid, prior period									$ 1,413,500	$ 1,609,009	$ 1,158,614
Prior periods									10,748	34,105	(209,359)
Current Period
Net losses paid, current period									71,989	179,461	176,172
Net incurred losses and LAE, current period									405,178	580,074	533,081
Total
Net losses paid									1,485,489	1,788,470	1,334,786
Net change in case and LAE reserves									(540,187)	(528,583)	(472,420)
Net change in IBNR reserves									(687,624)	(794,704)	(506,794)
Increase (reduction) in estimates of net ultimate losses									257,678	465,183	355,572
Increase (reduction) in provisions for unallocated LAE									(31,550)	(56,502)	(59,788)
Amortization of deferred charge assets and deferred gain liabilities									43,246	37,744	13,781
Amortization of fair value adjustments									27,506	50,573	7,493
Changes in fair value - fair value option									119,046	117,181	6,664
Total net incurred losses and LAE	$ 76,248	$ 109,686	$ 186,692	$ 43,300	$ 48,068	$ 163,258	$ 146,554	$ 256,299	415,926	614,179	323,722
Non-life Run-off
Prior Period
Net losses paid, prior period									1,064,911	1,182,804	838,812
Net change in case and LAE reserves, prior period									(449,610)	(553,996)	(552,124)
Net change in IBNR reserves, prior period									(742,417)	(847,893)	(573,127)
Increase (reduction) in estimates of net ultimate losses, prior period									(127,116)	(219,085)	(286,439)
Increase (reduction) in provisions for unallocated LAE, prior period									(48,407)	(57,844)	(65,401)
Amortization of deferred charge assets and deferred gain liabilities, prior period									42,640	37,744	13,781
Amortization of fair value adjustments, prior period									28,667	50,070	12,877
Changes in fair value - fair value option, prior period									119,046	117,181	6,664
Prior periods									14,830	(71,934)	(318,518)
Current Period
Net losses paid, current period									9,990	64,820	5
Net change in case and LAE reserves, current period									(3,470)	23,105	4,704
Net change in IBNR reserves, current period									24,003	35,194	7,742
Increase (reduction) in estimates of net ultimate losses, current period									30,523	123,119	12,451
Increase (reduction) in provisions for unallocated LAE, current period									(358)	440	0
Amortization of deferred charge assets and deferred gain liabilities, current period									0	0	0
Amortization of fair value adjustments, current period									0	0	0
Changes in fair value - fair value option, current period									0	0	0
Net incurred losses and LAE, current period									30,165	123,559	12,451
Total
Net losses paid									1,074,901	1,247,624	838,817
Net change in case and LAE reserves									(453,080)	(530,891)	(547,420)
Net change in IBNR reserves									(718,414)	(812,699)	(565,385)
Increase (reduction) in estimates of net ultimate losses									(96,593)	(95,966)	(273,988)
Increase (reduction) in provisions for unallocated LAE									(48,765)	(57,404)	(65,401)
Amortization of deferred charge assets and deferred gain liabilities									42,640	37,744	13,781
Amortization of fair value adjustments									28,667	50,070	12,877
Changes in fair value - fair value option									119,046	117,181	6,664
Total net incurred losses and LAE									44,995	51,625	(306,067)
Atrium
Prior Period
Net losses paid, prior period									40,196	43,572	28,969
Net change in case and LAE reserves, prior period									(14,145)	(13,278)	(10,161)
Net change in IBNR reserves, prior period									(31,773)	(38,380)	(27,507)
Increase (reduction) in estimates of net ultimate losses, prior period									(5,722)	(8,086)	(8,699)
Increase (reduction) in provisions for unallocated LAE, prior period									48	0	0
Amortization of fair value adjustments, prior period									(571)	335	(5,118)
Prior periods									(6,245)	(7,751)	(13,817)
Current Period
Net losses paid, current period									33,724	34,617	35,537
Net change in case and LAE reserves, current period									21,390	16,812	16,492
Net change in IBNR reserves, current period									38,434	33,598	31,598
Increase (reduction) in estimates of net ultimate losses, current period									93,548	85,027	83,627
Increase (reduction) in provisions for unallocated LAE, current period									(77)	0	0
Amortization of fair value adjustments, current period									0	0	0
Net incurred losses and LAE, current period									93,471	85,027	83,627
Total
Net losses paid									73,920	78,189	64,506
Net change in case and LAE reserves									7,245	3,534	6,331
Net change in IBNR reserves									6,661	(4,782)	4,091
Increase (reduction) in estimates of net ultimate losses									87,826	76,941	74,928
Increase (reduction) in provisions for unallocated LAE									(29)	0	0
Amortization of deferred charge assets and deferred gain liabilities									0	0	0
Amortization of fair value adjustments									(571)	335	(5,118)
Changes in fair value - fair value option									0	0	0
Total net incurred losses and LAE									87,226	77,276	69,810
StarStone
Prior Period
Net losses paid, prior period									300,037	375,377	289,981
Net change in case and LAE reserves, prior period									(130,502)	(95,183)	(77,821)
Net change in IBNR reserves, prior period									(165,909)	(163,340)	(87,963)
Increase (reduction) in estimates of net ultimate losses, prior period									3,626	116,854	124,197
Increase (reduction) in provisions for unallocated LAE, prior period									(466)	(2,666)	(3,042)
Amortization of deferred charge assets and deferred gain liabilities, prior period									606	0	0
Amortization of fair value adjustments, prior period									(590)	168	(266)
Prior periods									3,176	114,356	120,889
Current Period
Net losses paid, current period									26,831	75,458	137,390
Net change in case and LAE reserves, current period									35,458	90,497	141,682
Net change in IBNR reserves, current period									183,563	185,361	134,464
Increase (reduction) in estimates of net ultimate losses, current period									245,852	351,316	413,536
Increase (reduction) in provisions for unallocated LAE, current period									17,710	3,568	8,655
Amortization of deferred charge assets and deferred gain liabilities, current period									0	0	0
Amortization of fair value adjustments, current period									0	0	0
Net incurred losses and LAE, current period									263,562	354,884	422,191
Total
Net losses paid									326,868	450,835	427,371
Net change in case and LAE reserves									(95,044)	(4,686)	63,861
Net change in IBNR reserves									17,654	22,021	46,501
Increase (reduction) in estimates of net ultimate losses									249,478	468,170	537,733
Increase (reduction) in provisions for unallocated LAE									17,244	902	5,613
Amortization of deferred charge assets and deferred gain liabilities									606	0	0
Amortization of fair value adjustments									(590)	168	(266)
Changes in fair value - fair value option									0	0	0
Total net incurred losses and LAE									266,738	469,240	543,080
Other
Total
Net losses paid									9,800	11,822	4,092
Net change in case and LAE reserves									692	3,460	4,808
Net change in IBNR reserves									6,475	756	7,999
Increase (reduction) in estimates of net ultimate losses									16,967	16,038	16,899
Increase (reduction) in provisions for unallocated LAE									0	0	0
Amortization of deferred charge assets and deferred gain liabilities									0	0	0
Amortization of fair value adjustments									0	0	0
Changes in fair value - fair value option									0	0	0
Total net incurred losses and LAE									$ 16,967	$ 16,038	$ 16,899

Losses and Loss Adjustment Ex_6

Losses and Loss Adjustment Expenses - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)commutation	Dec. 31, 2019USD ($)policy_buy_backcommutation	Dec. 31, 2018USD ($)commutation
Effects of Reinsurance [Line Items]
Net liabilities relating to direct asbestos and environmental exposures	$ 1,900,000	$ 2,100,000
Asbestos and environmental liabilities	2,100,000	2,300,000
Increase (decrease) in asbestos and environmental reserves, gross	(178,200)	(419,900)
Increase (decrease) in asbestos and environmental reserves, net	(227,200)	(374,700)
Net losses paid, prior period	1,413,500	1,609,009	$ 1,158,614
Net incurred losses and LAE, current period	405,178	580,074	533,081
Changes in fair value - fair value option	119,046	117,181	6,664
Atrium
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	(5,722)	(8,086)	(8,699)
Net losses paid, prior period	40,196	43,572	28,969
Net change in case and LAE reserves, prior period	(14,145)	(13,278)	(10,161)
Downward incurred loss development	(31,773)	(38,380)	(27,507)
Increase (decrease) in net incurred losses and LAE, current period	10,000
Net incurred losses and LAE, current period	93,471	85,027	83,627
Changes in fair value - fair value option	0	0	0
Atrium | COVID-19
Effects of Reinsurance [Line Items]
Net incurred losses and LAE, current period	18,400
Non-life Run-off
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	(127,116)	(219,085)	(286,439)
Net losses paid, prior period	1,064,911	1,182,804	838,812
Net change in case and LAE reserves, prior period	(449,610)	(553,996)	(552,124)
Downward incurred loss development	(742,417)	(847,893)	(573,127)
Net incurred losses and LAE, current period	30,165	123,559	12,451
Changes in fair value - fair value option	119,046	117,181	6,664
Non-life Run-off | Workers' compensation/personal accident
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	(183,335)	(136,418)	(154,560)
Net losses paid, prior period	142,790	208,961	139,226
Net change in case and LAE reserves, prior period	(176,927)	(156,435)	(178,138)
Increase (decrease) in reported losses	(34,100)
Downward incurred loss development	(149,198)	(188,944)	$ (115,648)
Reduction of open inventory claims, percentage			(78.00%)
Non-life Run-off | Workers' compensation, two portfolios
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period		39,300
Net change in case and LAE reserves, prior period		53,600
Downward incurred loss development		14,300
Non-life Run-off | Six Communications
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	$ (10,800)	$ (6,100)
Number of commutations | commutation	10	6
Non-life Run-off | Seven Communications
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period			$ 11,200
Number of commutations | commutation			7
Non-life Run-off | Marine, aviation and transit
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	$ (31,089)	$ (20,408)	$ 2,443
Net losses paid, prior period	33,927	82,058	67,831
Net change in case and LAE reserves, prior period	(14,458)	(77,958)	(44,200)
Downward incurred loss development	(50,558)	(24,508)	(21,188)
Non-life Run-off | General Casualty
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	(25,663)	(6,742)	(34,444)
Net losses paid, prior period	170,502	175,044	141,624
Net change in case and LAE reserves, prior period	(68,744)	(89,968)	(115,240)
Downward incurred loss development	(127,421)	(91,818)	(60,828)
Non-life Run-off | Motor
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	147,765	(37,451)	(39,995)
Net losses paid, prior period	349,366	276,563	104,182
Net change in case and LAE reserves, prior period	(106,561)	(134,127)	(109,962)
Downward incurred loss development	(95,040)	(179,887)	(34,215)
Non-life Run-off | Professional indemnity/ Directors & Officers
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	(11,605)	(38,557)	19,681
Net losses paid, prior period	63,878	103,413	161,797
Net change in case and LAE reserves, prior period	3,698	(36,986)	(11,159)
Downward incurred loss development	(79,181)	(104,984)	(130,957)
Ceded reinsurance asset increase		13,500
Non-life Run-off | Asbestos
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	(18,501)	6,811	(64,949)
Net losses paid, prior period	132,853	118,557	108,248
Net change in case and LAE reserves, prior period	(1,300)	35,003	(21,535)
Downward incurred loss development	(150,054)	(146,749)	$ (151,662)
Volume of claims reported, percentage, less than			3.00%
Average cost per claims, percentage			5.00%
Non-life Run-off | Asbestos Exposure, Six Commutations
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period		$ (9,800)
Number of commutations | commutation		6
Non-life Run-off | Asbestos Exposure, Eight Communications and Two Policy Buy-Backs
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period			$ (9,500)
Number of commutations | commutation			8
Number of policy buy-backs | policy_buy_back		2
Non-life Run-off | Product And Service Other Than Workers' Compensation
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	$ (12,300)
Number of commutations | commutation	15
StarStone
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period	$ 3,626	$ 116,854	$ 124,197
Net losses paid, prior period	300,037	375,377	289,981
Net change in case and LAE reserves, prior period	(130,502)	(95,183)	(77,821)
Downward incurred loss development	(165,909)	(163,340)	(87,963)
Increase (decrease) in net incurred losses and LAE, current period	(202,500)	(73,800)
Net incurred losses and LAE, current period	263,562	354,884	422,191
Changes in fair value - fair value option	0	$ 0	0
StarStone | COVID-19
Effects of Reinsurance [Line Items]
Net incurred losses and LAE, current period	$ 52,800
Short-duration Insurance Contracts, Accident Years 1995-2005 | Non-life Run-off | Workers' compensation/personal accident
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period			22,700
Net change in case and LAE reserves, prior period			37,000
Downward incurred loss development			14,300
Short-duration Insurance Contracts, Accident Years 2010-2014 | Non-life Run-off | Workers' compensation/personal accident
Effects of Reinsurance [Line Items]
Increase (reduction) in estimates of net ultimate losses, prior period			$ (30,200)

Losses and Loss Adjustment Ex_7

Losses and Loss Adjustment Expenses - Net Incurred Losses by Line of Business (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	$ 1,413,500	$ 1,609,009	$ 1,158,614
Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	1,064,911	1,182,804	838,812
Net change in case and LAE reserves, prior period	(449,610)	(553,996)	(552,124)
Net change in IBNR reserves, prior period	(742,417)	(847,893)	(573,127)
Increase (reduction) in estimates of net ultimate losses, prior period	(127,116)	(219,085)	(286,439)
Asbestos | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	132,853	118,557	108,248
Net change in case and LAE reserves, prior period	(1,300)	35,003	(21,535)
Net change in IBNR reserves, prior period	(150,054)	(146,749)	(151,662)
Increase (reduction) in estimates of net ultimate losses, prior period	(18,501)	6,811	(64,949)
Environmental | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	23,866	16,899	21,273
Net change in case and LAE reserves, prior period	(266)	13,796	479
Net change in IBNR reserves, prior period	(36,362)	(15,707)	(7,599)
Increase (reduction) in estimates of net ultimate losses, prior period	(12,762)	14,988	14,153
General Casualty | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	170,502	175,044	141,624
Net change in case and LAE reserves, prior period	(68,744)	(89,968)	(115,240)
Net change in IBNR reserves, prior period	(127,421)	(91,818)	(60,828)
Increase (reduction) in estimates of net ultimate losses, prior period	(25,663)	(6,742)	(34,444)
Workers' compensation/personal accident | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	142,790	208,961	139,226
Net change in case and LAE reserves, prior period	(176,927)	(156,435)	(178,138)
Net change in IBNR reserves, prior period	(149,198)	(188,944)	(115,648)
Increase (reduction) in estimates of net ultimate losses, prior period	(183,335)	(136,418)	(154,560)
Marine, aviation and transit | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	33,927	82,058	67,831
Net change in case and LAE reserves, prior period	(14,458)	(77,958)	(44,200)
Net change in IBNR reserves, prior period	(50,558)	(24,508)	(21,188)
Increase (reduction) in estimates of net ultimate losses, prior period	(31,089)	(20,408)	2,443
Construction defect | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	27,476	32,078	22,182
Net change in case and LAE reserves, prior period	(6,092)	(8,313)	(7,257)
Net change in IBNR reserves, prior period	(13,382)	(25,025)	(33,146)
Increase (reduction) in estimates of net ultimate losses, prior period	8,002	(1,260)	(18,221)
Professional indemnity/ Directors & Officers | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	63,878	103,413	161,797
Net change in case and LAE reserves, prior period	3,698	(36,986)	(11,159)
Net change in IBNR reserves, prior period	(79,181)	(104,984)	(130,957)
Increase (reduction) in estimates of net ultimate losses, prior period	(11,605)	(38,557)	19,681
Motor | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	349,366	276,563	104,182
Net change in case and LAE reserves, prior period	(106,561)	(134,127)	(109,962)
Net change in IBNR reserves, prior period	(95,040)	(179,887)	(34,215)
Increase (reduction) in estimates of net ultimate losses, prior period	147,765	(37,451)	(39,995)
Property | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	71,422	94,093	22,178
Net change in case and LAE reserves, prior period	(24,356)	(73,259)	(24,271)
Net change in IBNR reserves, prior period	(64,331)	(7,358)	(11,497)
Increase (reduction) in estimates of net ultimate losses, prior period	(17,265)	13,476	(13,590)
All Other | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Net losses paid, prior period	48,831	75,138	50,271
Net change in case and LAE reserves, prior period	(54,604)	(25,749)	(40,841)
Net change in IBNR reserves, prior period	23,110	(62,913)	(6,387)
Increase (reduction) in estimates of net ultimate losses, prior period	$ 17,337	$ (13,524)	$ 3,043

Losses and Loss Adjustment Ex_8

Losses and Loss Adjustment Expenses - Breakdown of Gross and Net Losses and LAE Reserves by Major Category (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Gross
OLR	$ 5,127,849	$ 5,249,565
IBNR	5,277,503	4,651,649
Fair value adjustments - acquired companies	(143,183)	(167,511)
Fair value adjustments - fair value option	(54,589)	(217,933)
Total	10,593,282	9,868,404	$ 9,048,796	$ 7,100,488
Net
ULAE	385,702	352,634
Total	8,544,940	7,681,193	7,253,939
Non-life Run-off
Gross
OLR	4,440,425	4,407,082
IBNR	4,641,500	3,945,407
Total	9,081,925	8,352,489
Fair value adjustments - acquired companies	(142,854)	(170,689)
Fair value adjustments - fair value option	(54,589)	(217,933)
Net deferred charge assets and gains on retroactive reinsurance	0	0
ULAE	350,600	331,494
Total	9,235,082	8,295,361	7,540,662	5,949,472
Net
OLR	3,502,195	3,434,789
IBNR	4,133,418	3,272,348
Total Net Reserves	7,635,613	6,707,137
Fair value adjustments	(128,841)	(157,036)
Fair value adjustments - fair value option	(33,163)	(129,848)
Net deferred charge assets and gains on retroactive reinsurance	(218,722)	(259,587)
ULAE	333,913	331,494
Total	7,588,800	6,492,160	6,087,954
Non-life Run-off | Asbestos
Gross
OLR	544,438	542,681
IBNR	1,234,101	1,373,678
Total	1,778,539	1,916,359
Net
OLR	464,102	490,117
IBNR	1,122,021	1,271,982
Total Net Reserves	1,586,123	1,762,099
Non-life Run-off | Environmental
Gross
OLR	184,783	187,165
IBNR	118,111	156,121
Total	302,894	343,286
Net
OLR	164,709	173,878
IBNR	100,339	142,351
Total Net Reserves	265,048	316,229
Non-life Run-off | General Casualty
Gross
OLR	610,437	501,863
IBNR	1,279,991	489,129
Total	1,890,428	990,992
Net
OLR	492,039	399,396
IBNR	1,247,662	421,426
Total Net Reserves	1,739,701	820,822
Non-life Run-off | Workers' compensation/personal accident
Gross
OLR	1,087,324	1,270,530
IBNR	918,238	977,808
Total	2,005,562	2,248,338
Net
OLR	912,068	963,578
IBNR	776,941	751,074
Total Net Reserves	1,689,009	1,714,652
Non-life Run-off | Marine, aviation and transit
Gross
OLR	271,469	290,067
IBNR	73,081	121,577
Total	344,550	411,644
Net
OLR	229,464	244,611
IBNR	56,414	100,135
Total Net Reserves	285,878	344,746
Non-life Run-off | Construction defect
Gross
OLR	23,380	29,772
IBNR	85,578	98,312
Total	108,958	128,084
Net
OLR	23,109	29,245
IBNR	83,039	94,888
Total Net Reserves	106,148	124,133
Non-life Run-off | Professional indemnity/ Directors & Officers
Gross
OLR	764,768	693,760
IBNR	336,705	265,490
Total	1,101,473	959,250
Net
OLR	526,333	485,478
IBNR	307,349	170,926
Total Net Reserves	833,682	656,404
Non-life Run-off | Motor
Gross
OLR	619,682	480,668
IBNR	355,044	233,806
Total	974,726	714,474
Net
OLR	451,097	317,829
IBNR	283,576	165,543
Total Net Reserves	734,673	483,372
Non-life Run-off | Property
Gross
OLR	116,398	140,620
IBNR	35,832	63,604
Total	152,230	204,224
Net
OLR	97,826	122,010
IBNR	34,182	56,450
Total Net Reserves	132,008	178,460
Non-life Run-off | All Other
Gross
OLR	217,746	269,956
IBNR	204,819	165,882
Total	422,565	435,838
Net
OLR	141,448	208,647
IBNR	121,895	97,573
Total Net Reserves	263,343	306,220
Atrium
Gross
OLR		89,141
IBNR		136,543
Total		225,684
Fair value adjustments - acquired companies		3,700
ULAE		2,288
Total	0	231,672	241,284	240,873
Net
OLR		80,130
IBNR		117,257
Total Net Reserves		197,387
Fair value adjustments		3,181
ULAE		2,288
Total	0	202,856	202,516
Atrium | Marine, aviation and transit
Gross
OLR		24,668
IBNR		34,156
Total		58,824
Net
OLR		21,012
IBNR		24,829
Total Net Reserves		45,841
Atrium | Binding Authorities
Gross
OLR		31,507
IBNR		54,039
Total		85,546
Net
OLR		29,590
IBNR		51,984
Total Net Reserves		81,574
Atrium | Reinsurance
Gross
OLR		18,385
IBNR		29,533
Total		47,918
Net
OLR		16,209
IBNR		23,338
Total Net Reserves		39,547
Atrium | Accident and Health
Gross
OLR		5,460
IBNR		7,880
Total		13,340
Net
OLR		4,735
IBNR		7,469
Total Net Reserves		12,204
Atrium | Non-Marine Direct and Facultative
Gross
OLR		9,121
IBNR		10,935
Total		20,056
Net
OLR		8,584
IBNR		9,637
Total Net Reserves		18,221
StarStone
Gross
OLR	677,220	743,830
IBNR	615,963	556,134
Total	1,293,183	1,299,964
Fair value adjustments - acquired companies	(329)	(522)
ULAE	35,102	18,852
Total	1,327,956	1,318,294	1,247,989	$ 910,143
Net
OLR	413,582	479,699
IBNR	476,203	462,949
Total Net Reserves	889,785	942,648
Fair value adjustments	1,010	1,600
ULAE	35,101	18,852
Total	925,896	963,100	$ 944,608
StarStone | General Casualty
Gross
OLR	115,295	121,945
IBNR	276,941	210,969
Total	392,236	332,914
Net
OLR	98,721	108,543
IBNR	232,433	204,800
Total Net Reserves	331,154	313,343
StarStone | Workers' compensation/personal accident
Gross
OLR	12,044	15,089
IBNR	11,589	19,865
Total	23,633	34,954
Net
OLR	12,044	15,089
IBNR	11,589	19,865
Total Net Reserves	23,633	34,954
StarStone | Property
Gross
OLR	322,735	341,677
IBNR	117,240	131,596
Total	439,975	473,273
Net
OLR	141,089	150,559
IBNR	81,459	87,653
Total Net Reserves	222,548	238,212
StarStone | Marine
Gross
OLR	142,631	189,355
IBNR	174,015	161,379
Total	316,646	350,734
Net
OLR	119,628	158,252
IBNR	132,482	128,242
Total Net Reserves	252,110	286,494
StarStone | Aerospace
Gross
OLR	84,515	75,764
IBNR	36,178	32,325
Total	120,693	108,089
Net
OLR	42,100	47,256
IBNR	18,240	22,389
Total Net Reserves	$ 60,340	$ 69,645

Losses and Loss Adjustment Ex_9

Losses and Loss Adjustment Expenses - Net Loss Reserves By Acquisition And Year (Details) - Non-life Run-off $ in Thousands	Dec. 31, 2020USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	$ 7,587,170
Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,563,706
Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	261,387
General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,732,445
Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,687,272
Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	283,868
Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	106,135
Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	833,085
Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	732,268
Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	130,309
All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	256,695
2010 and Prior
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	329,442
2010 and Prior | Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	142,028
2010 and Prior | Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	42,356
2010 and Prior | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	52,582
2010 and Prior | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	42,908
2010 and Prior | Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	8,760
2010 and Prior | Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	43
2010 and Prior | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	7,539
2010 and Prior | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	12,452
2010 and Prior | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	3,301
2010 and Prior | All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	17,473
2011
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	152,446
2011 | Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2011 | Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2011 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	13,270
2011 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	125,649
2011 | Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	2,747
2011 | Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2011 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	9,564
2011 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	201
2011 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	161
2011 | All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	854
2012
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	43,173
2012 | Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2012 | Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2012 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	9,983
2012 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2012 | Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2012 | Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2012 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	23,210
2012 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	276
2012 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	7,008
2012 | All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	2,696
2013
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	76,742
2013 | Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	7,767
2013 | Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2013 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	16,696
2013 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	48,207
2013 | Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	(188)
2013 | Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2013 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2013 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2013 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2013 | All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	4,260
2014
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	92,450
2014 | Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2014 | Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2014 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	31,610
2014 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2014 | Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	10,592
2014 | Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2014 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	20,942
2014 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,465
2014 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	18,165
2014 | All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	9,676
2015
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	384,217
2015 | Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2015 | Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2015 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	34,704
2015 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	287,653
2015 | Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,616
2015 | Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	36,258
2015 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2015 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	13,147
2015 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	3,880
2015 | All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	6,959
2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	835,389
2016 | Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	407,958
2016 | Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	89,865
2016 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	3,727
2016 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	219,157
2016 | Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	32
2016 | Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	14,289
2016 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	76,314
2016 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2016 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	465
2016 | All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	23,582
2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,042,254
2017 | Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	726,901
2017 | Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	22,891
2017 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	44,551
2017 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	53,659
2017 | Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	77,321
2017 | Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	18,836
2017 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2017 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	3,710
2017 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	(114)
2017 | All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	94,499
2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,327,860
2018 | Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,105
2018 | Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	11,203
2018 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	228,419
2018 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	322,737
2018 | Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	106,431
2018 | Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2018 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	331,676
2018 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	260,797
2018 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	47,270
2018 | All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	18,222
2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,339,435
2019 | Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	277,947
2019 | Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	95,072
2019 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	218,995
2019 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	387,438
2019 | Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	56,709
2019 | Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	36,709
2019 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	130,906
2019 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	17,899
2019 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	39,286
2019 | All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	78,474
2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,963,762
2020 | Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2020 | Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2020 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,077,908
2020 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	199,864
2020 | Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	19,848
2020 | Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2020 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	232,934
2020 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	422,321
2020 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	10,887
2020 | All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	$ 0

Losses and Loss Adjustment E_10

Losses and Loss Adjustment Expenses - Reconciliation Of Net Incurred Losses Prior To Provision For Bad Debt (Details) - Non-life Run-off - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	$ 7,587,170
Provision for Bad Debt	48,443
Total Net Reserves	7,635,613	$ 6,707,137
Asbestos
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	1,563,706
Provision for Bad Debt	22,417
Total Net Reserves	1,586,123	1,762,099
Environmental
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	261,387
Provision for Bad Debt	3,661
Total Net Reserves	265,048	316,229
General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	1,732,445
Provision for Bad Debt	7,256
Total Net Reserves	1,739,701	820,822
Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	1,687,272
Provision for Bad Debt	1,737
Total Net Reserves	1,689,009	1,714,652
Marine, aviation and transit
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	283,868
Provision for Bad Debt	2,010
Total Net Reserves	285,878	344,746
Construction defect
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	106,135
Provision for Bad Debt	13
Total Net Reserves	106,148	124,133
Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	833,085
Provision for Bad Debt	597
Total Net Reserves	833,682	656,404
Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	732,268
Provision for Bad Debt	2,405
Total Net Reserves	734,673	483,372
Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	130,309
Provision for Bad Debt	1,699
Total Net Reserves	132,008	178,460
All Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves per all Acquisition Years	256,695
Provision for Bad Debt	6,648
Total Net Reserves	$ 263,343	$ 306,220

Losses and Loss Adjustment E_11

Losses and Loss Adjustment Expenses - Loss Triangles (Details) $ in Thousands	Dec. 31, 2020USD ($)claim	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)	Dec. 31, 2011USD ($)
Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	$ 7,587,170
Non-life Run-off | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,687,272
Non-life Run-off | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,732,445
Non-life Run-off | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	732,268
Non-life Run-off | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	833,085
Non-life Run-off | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	130,309
StarStone | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	112,244
IBNR losses and loss expenses, net of reinsurance	$ 11,589
Cumulative Number of Claims | claim	1,129
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 88,611
Liabilities for unpaid losses and allocated LAE, net of reinsurance	23,633
StarStone | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	967,951
IBNR losses and loss expenses, net of reinsurance	$ 232,433
Cumulative Number of Claims | claim	39,628
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 636,797
Liabilities for unpaid losses and allocated LAE, net of reinsurance	331,154
StarStone | Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	974,161
IBNR losses and loss expenses, net of reinsurance	$ 132,482
Cumulative Number of Claims | claim	54,037
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 722,051
Liabilities for unpaid losses and allocated LAE, net of reinsurance	252,110
StarStone | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,139,045
IBNR losses and loss expenses, net of reinsurance	$ 81,459
Cumulative Number of Claims | claim	71,266
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 916,497
Liabilities for unpaid losses and allocated LAE, net of reinsurance	222,548
StarStone | Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	533,320
IBNR losses and loss expenses, net of reinsurance	$ 18,240
Cumulative Number of Claims | claim	25,624
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 472,980
Liabilities for unpaid losses and allocated LAE, net of reinsurance	60,340
StarStone | Accident Year - 2010 and Prior | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0	0	0	0	0
StarStone | Accident Year - 2010 and Prior | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	102,661	102,317	102,539	101,801	101,444	101,217	100,449
IBNR losses and loss expenses, net of reinsurance	$ 19
Cumulative Number of Claims | claim	4,322
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 101,886	101,813	101,783	101,712	101,326	101,181	99,643
StarStone | Accident Year - 2010 and Prior | Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	46,828	47,213	47,175	47,287	47,194	47,336	50,395
IBNR losses and loss expenses, net of reinsurance	$ 62
Cumulative Number of Claims | claim	3,037
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 46,709	46,682	46,563	46,470	46,464	46,360	44,212
StarStone | Accident Year - 2010 and Prior | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	190,667	189,079	188,778	187,846	187,286	188,537	190,649
IBNR losses and loss expenses, net of reinsurance	$ 13
Cumulative Number of Claims | claim	4,485
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 188,080	187,300	187,285	187,264	187,040	186,876	183,649
StarStone | Accident Year - 2010 and Prior | Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	18,693	18,759	18,962	18,906	18,393	18,083	18,439
IBNR losses and loss expenses, net of reinsurance	$ 36
Cumulative Number of Claims | claim	622
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 18,538	18,535	18,480	18,209	17,141	16,530	15,391
StarStone | Accident Year - 2011 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0	0	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0	0	0	0	0
StarStone | Accident Year - 2011 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	28,027	27,859	27,703	19,103	19,681	18,740	16,244
IBNR losses and loss expenses, net of reinsurance	$ 429
Cumulative Number of Claims | claim	2,962
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 27,426	27,401	27,385	18,760	18,354	15,941	12,394
StarStone | Accident Year - 2011 | Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	28,075	27,956	28,162	27,824	27,767	28,190	29,890
IBNR losses and loss expenses, net of reinsurance	$ 229
Cumulative Number of Claims | claim	1,966
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 27,285	27,082	27,057	26,942	26,688	25,686	24,599
StarStone | Accident Year - 2011 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	90,406	90,259	89,918	90,018	90,328	90,272	91,712
IBNR losses and loss expenses, net of reinsurance	$ 88
Cumulative Number of Claims | claim	1,635
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 90,110	89,940	89,894	89,894	89,662	89,149	87,937
StarStone | Accident Year - 2011 | Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	58,299	58,677	59,578	58,084	57,653	57,226	58,748
IBNR losses and loss expenses, net of reinsurance	$ 96
Cumulative Number of Claims | claim	2,179
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 57,483	57,482	56,954	56,394	55,817	55,133	53,785
StarStone | Accident Year - 2012 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0	0	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0	0	0	0	0
StarStone | Accident Year - 2012 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	37,072	36,159	33,511	28,482	30,788	33,853	39,797
IBNR losses and loss expenses, net of reinsurance	$ 3,418
Cumulative Number of Claims | claim	3,521
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 32,706	32,666	32,644	23,711	22,746	20,634	13,336
StarStone | Accident Year - 2012 | Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	48,706	49,176	51,231	50,435	51,710	52,010	48,204
IBNR losses and loss expenses, net of reinsurance	$ 307
Cumulative Number of Claims | claim	2,431
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 47,452	46,178	45,951	45,498	44,681	42,787	38,570
StarStone | Accident Year - 2012 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	58,247	59,463	59,201	62,177	61,243	62,119	66,137
IBNR losses and loss expenses, net of reinsurance	$ 133
Cumulative Number of Claims | claim	1,516
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 58,100	58,099	55,895	55,672	54,681	52,442	48,322
StarStone | Accident Year - 2012 | Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	56,907	56,771	57,044	55,823	55,870	55,087	55,293
IBNR losses and loss expenses, net of reinsurance	$ 186
Cumulative Number of Claims | claim	2,375
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 55,290	55,160	54,415	53,271	51,787	49,009	45,618
StarStone | Accident Year - 2013 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1	1	1	0	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1	1	1	0	0	0	0
StarStone | Accident Year - 2013 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	67,638	63,323	56,145	53,493	54,282	47,304	51,458
IBNR losses and loss expenses, net of reinsurance	$ 9,044
Cumulative Number of Claims | claim	4,821
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 52,333	48,898	42,123	38,866	35,799	22,131	16,373
StarStone | Accident Year - 2013 | Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	63,323	64,399	58,209	54,790	53,783	55,981	63,442
IBNR losses and loss expenses, net of reinsurance	$ 926
Cumulative Number of Claims | claim	2,202
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 62,037	57,539	47,698	45,575	43,027	38,880	29,436
StarStone | Accident Year - 2013 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	61,383	61,114	62,711	64,521	65,394	65,608	78,501
IBNR losses and loss expenses, net of reinsurance	$ 152
Cumulative Number of Claims | claim	1,955
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 61,060	60,916	59,756	53,548	51,431	46,556	31,000
StarStone | Accident Year - 2013 | Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	78,673	76,774	77,222	74,733	70,255	69,976	71,930
IBNR losses and loss expenses, net of reinsurance	$ 297
Cumulative Number of Claims | claim	2,538
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 73,923	73,309	72,573	68,574	63,226	59,639	50,725
StarStone | Accident Year - 2014 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	9,372	9,666	9,867	10,180	11,889	11,179	10,145
IBNR losses and loss expenses, net of reinsurance	$ 500
Cumulative Number of Claims | claim	137
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 8,503	8,201	7,957	7,430	6,031	3,951	969
StarStone | Accident Year - 2014 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	72,097	75,513	66,585	66,559	67,461	67,141	66,094
IBNR losses and loss expenses, net of reinsurance	$ 10,495
Cumulative Number of Claims | claim	4,863
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 51,949	49,571	46,654	36,802	27,043	16,141	4,318
StarStone | Accident Year - 2014 | Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	49,676	51,062	51,642	56,049	49,449	54,370	50,959
IBNR losses and loss expenses, net of reinsurance	$ 1,003
Cumulative Number of Claims | claim	3,944
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 44,740	44,727	43,323	37,594	33,076	25,306	11,037
StarStone | Accident Year - 2014 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	40,612	41,226	41,968	44,081	43,631	44,130	59,390
IBNR losses and loss expenses, net of reinsurance	$ 794
Cumulative Number of Claims | claim	2,125
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 39,681	37,609	36,461	34,869	31,854	18,945	5,517
StarStone | Accident Year - 2014 | Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	45,978	48,757	54,534	52,471	53,533	53,457	65,227
IBNR losses and loss expenses, net of reinsurance	$ 485
Cumulative Number of Claims | claim	2,867
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 43,868	43,858	43,857	40,749	38,494	31,192	17,297
StarStone | Accident Year - 2015 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	28,768	29,757	30,742	32,567	36,078	35,735
IBNR losses and loss expenses, net of reinsurance	$ 1,870
Cumulative Number of Claims | claim	259
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 25,032	24,301	22,952	19,785	13,126	4,135
StarStone | Accident Year - 2015 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	101,191	99,425	92,904	81,685	82,050	76,470
IBNR losses and loss expenses, net of reinsurance	$ 13,037
Cumulative Number of Claims | claim	4,323
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 75,875	69,948	50,598	36,971	21,503	6,439
StarStone | Accident Year - 2015 | Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	80,438	83,646	81,864	80,196	70,160	70,492
IBNR losses and loss expenses, net of reinsurance	$ 1,612
Cumulative Number of Claims | claim	5,606
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 62,401	59,918	56,557	50,376	30,143	10,234
StarStone | Accident Year - 2015 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	69,314	68,678	67,733	67,944	73,946	75,514
IBNR losses and loss expenses, net of reinsurance	$ 1,377
Cumulative Number of Claims | claim	11,435
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 62,826	62,237	61,347	52,799	25,890	8,756
StarStone | Accident Year - 2015 | Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	69,879	69,612	71,624	70,903	67,846	64,550
IBNR losses and loss expenses, net of reinsurance	$ 1,070
Cumulative Number of Claims | claim	2,962
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 65,630	64,811	62,522	59,342	50,844	31,417
StarStone | Accident Year - 2016 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	36,293	38,739	37,703	35,179	40,912
IBNR losses and loss expenses, net of reinsurance	$ 2,847
Cumulative Number of Claims | claim	277
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 29,539	27,632	22,940	15,229	5,170
StarStone | Accident Year - 2016 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	128,139	135,670	111,020	95,726	92,406
IBNR losses and loss expenses, net of reinsurance	$ 25,293
Cumulative Number of Claims | claim	3,825
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 92,223	76,175	59,074	32,864	4,206
StarStone | Accident Year - 2016 | Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	89,309	88,023	88,459	83,187	80,830
IBNR losses and loss expenses, net of reinsurance	$ 4,150
Cumulative Number of Claims | claim	6,658
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 76,534	73,778	58,438	41,875	11,669
StarStone | Accident Year - 2016 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	94,450	91,956	92,038	91,680	83,622
IBNR losses and loss expenses, net of reinsurance	$ 1,361
Cumulative Number of Claims | claim	14,167
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 83,577	81,904	72,244	54,188	23,803
StarStone | Accident Year - 2016 | Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	42,954	43,991	46,832	43,371	35,923
IBNR losses and loss expenses, net of reinsurance	$ 1,463
Cumulative Number of Claims | claim	2,925
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 37,933	37,909	35,884	30,516	11,001
StarStone | Accident Year - 2017 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	23,320	22,900	29,931	28,188
IBNR losses and loss expenses, net of reinsurance	$ 3,888
Cumulative Number of Claims | claim	295
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 16,520	14,600	10,436	3,560
StarStone | Accident Year - 2017 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	166,472	161,288	135,743	100,585
IBNR losses and loss expenses, net of reinsurance	$ 34,822
Cumulative Number of Claims | claim	3,899
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 114,062	87,902	41,896	7,712
StarStone | Accident Year - 2017 | Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	162,629	166,304	158,450	125,976
IBNR losses and loss expenses, net of reinsurance	$ 7,959
Cumulative Number of Claims | claim	8,352
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 125,335	107,787	68,233	23,986
StarStone | Accident Year - 2017 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	171,673	181,855	169,673	152,172
IBNR losses and loss expenses, net of reinsurance	$ 4,429
Cumulative Number of Claims | claim	14,553
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 146,340	137,569	96,151	34,961
StarStone | Accident Year - 2017 | Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	52,590	54,980	33,623	28,816
IBNR losses and loss expenses, net of reinsurance	$ 2,193
Cumulative Number of Claims | claim	3,381
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 46,134	44,582	26,857	9,000
StarStone | Accident Year - 2018 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	14,490	14,814	15,100
IBNR losses and loss expenses, net of reinsurance	$ 2,484
Cumulative Number of Claims | claim	161
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 9,016	6,431	2,574
StarStone | Accident Year - 2018 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	106,014	101,381	87,781
IBNR losses and loss expenses, net of reinsurance	$ 39,329
Cumulative Number of Claims | claim	2,929
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 54,000	34,762	18,747
StarStone | Accident Year - 2018 | Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	161,831	164,042	164,461
IBNR losses and loss expenses, net of reinsurance	$ 16,444
Cumulative Number of Claims | claim	10,123
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 129,632	103,930	40,698
StarStone | Accident Year - 2018 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	174,137	172,640	161,507
IBNR losses and loss expenses, net of reinsurance	$ 11,123
Cumulative Number of Claims | claim	11,891
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 126,763	93,275	60,944
StarStone | Accident Year - 2018 | Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	54,831	54,969	58,573
IBNR losses and loss expenses, net of reinsurance	$ 3,491
Cumulative Number of Claims | claim	3,390
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 43,284	39,531	24,979
StarStone | Accident Year - 2019 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
StarStone | Accident Year - 2019 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	59,902	42,595
IBNR losses and loss expenses, net of reinsurance	$ 23,758
Cumulative Number of Claims | claim	2,581
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 26,235	4,721
StarStone | Accident Year - 2019 | Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	158,919	152,423
IBNR losses and loss expenses, net of reinsurance	$ 39,463
Cumulative Number of Claims | claim	7,015
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 84,414	33,196
StarStone | Accident Year - 2019 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	117,009	116,634
IBNR losses and loss expenses, net of reinsurance	$ 22,609
Cumulative Number of Claims | claim	6,166
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 52,637	19,461
StarStone | Accident Year - 2019 | Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	45,784	45,401
IBNR losses and loss expenses, net of reinsurance	$ 5,148
Cumulative Number of Claims | claim	2,028
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 30,210	23,294
StarStone | Accident Year - 2020 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
StarStone | Accident Year - 2020 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	98,738
IBNR losses and loss expenses, net of reinsurance	$ 72,789
Cumulative Number of Claims | claim	1,582
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 8,102
StarStone | Accident Year - 2020 | Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	84,427
IBNR losses and loss expenses, net of reinsurance	$ 60,327
Cumulative Number of Claims | claim	2,703
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 15,512
StarStone | Accident Year - 2020 | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	71,147
IBNR losses and loss expenses, net of reinsurance	$ 39,380
Cumulative Number of Claims | claim	1,338
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 7,323
StarStone | Accident Year - 2020 | Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	8,732
IBNR losses and loss expenses, net of reinsurance	$ 3,775
Cumulative Number of Claims | claim	357
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 687
2011 | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	597,263
Incurred losses and allocated loss adjustment expenses, net of reinsurance	229,564
IBNR losses and loss expenses, net of reinsurance	$ 17,506
Cumulative Number of Claims | claim	112,901
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 77,118
Liabilities for unpaid losses and allocated LAE, net of reinsurance	152,446
2011 | Non-life Run-off | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	125,649
2011 | Non-life Run-off | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	13,270
2011 | Non-life Run-off | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	201
2011 | Non-life Run-off | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	9,564
2011 | Non-life Run-off | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	161
2011 | Non-life Run-off | Accident Year - 2010 and Prior
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	597,263
Incurred losses and allocated loss adjustment expenses, net of reinsurance	229,458	240,808	261,234	274,136	319,423	375,227	426,777	$ 489,877	$ 589,004	$ 621,819
IBNR losses and loss expenses, net of reinsurance	$ 17,493
Cumulative Number of Claims | claim	112,837
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 77,051	56,741	31,108	19,697	27,563	19,370	24,238	90,711	98,969	58,934
2011 | Non-life Run-off | Accident Year - 2011
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	100	93	86	79	71	61	54	45	36	102
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	19
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 100	93	86	79	71	61	54	46	36	$ 27
2011 | Non-life Run-off | Accident Year - 2012
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	17	17	18	17	10	10	10	11	122
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	7
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 17	17	17	17	10	10	10	10	6
2011 | Non-life Run-off | Accident Year - 2013
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	15	15	15	15	15	15	43	23
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	16
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 15	15	15	15	15	15	11	6
2011 | Non-life Run-off | Accident Year - 2014
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	14	15	18	3	3	3	1
IBNR losses and loss expenses, net of reinsurance	$ 2
Cumulative Number of Claims | claim	14
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 7	7	4	3	3	3	1
2011 | Non-life Run-off | Accident Year - 2015
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	19	24	32	(2)	(2)	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 18	11	2	(2)	(2)	(1)
2011 | Non-life Run-off | Accident Year - 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	(88)	(99)	(111)	(139)	2
IBNR losses and loss expenses, net of reinsurance	$ 7
Cumulative Number of Claims | claim	2
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ (105)	(114)	(125)	(153)	2
2011 | Non-life Run-off | Accident Year - 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	17	15	21	0
IBNR losses and loss expenses, net of reinsurance	$ 1
Cumulative Number of Claims | claim	2
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 10	6	3	0
2011 | Non-life Run-off | Accident Year - 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	8	8	7
IBNR losses and loss expenses, net of reinsurance	$ 1
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 5	4	1
2011 | Non-life Run-off | Accident Year - 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	2	0
IBNR losses and loss expenses, net of reinsurance	$ 1
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
2011 | Non-life Run-off | Accident Year - 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	2
IBNR losses and loss expenses, net of reinsurance	$ 1
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2012 | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	327,044
Incurred losses and allocated loss adjustment expenses, net of reinsurance	256,388
IBNR losses and loss expenses, net of reinsurance	$ 10,942
Cumulative Number of Claims | claim	47,815
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 213,215
Liabilities for unpaid losses and allocated LAE, net of reinsurance	43,173
2012 | Non-life Run-off | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2012 | Non-life Run-off | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	9,983
2012 | Non-life Run-off | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	276
2012 | Non-life Run-off | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	23,210
2012 | Non-life Run-off | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	7,008
2012 | Non-life Run-off | Accident Year - 2010 and Prior
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	326,229
Incurred losses and allocated loss adjustment expenses, net of reinsurance	252,318	263,472	269,004	277,778	286,660	297,081	312,510	321,295	328,419
IBNR losses and loss expenses, net of reinsurance	$ 10,889
Cumulative Number of Claims | claim	47,773
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 209,656	204,482	194,011	180,270	169,781	144,553	112,966	70,440	3,194
2012 | Non-life Run-off | Accident Year - 2011
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	1,487
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,032	1,032	1,032	1,049	1,072	1,095	1,182	1,336	1,466
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	5
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,032	1,032	1,032	990	928	866	742	496	120
2012 | Non-life Run-off | Accident Year - 2012
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	55
Incurred losses and allocated loss adjustment expenses, net of reinsurance	167	167	167	397	406	344	363	49	81
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	6
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 167	167	167	167	167	52	49	49	$ 31
2012 | Non-life Run-off | Accident Year - 2013
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	136	136	136	421	433	427	119	946
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	5
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 136	136	136	136	136	136	119	109
2012 | Non-life Run-off | Accident Year - 2014
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	(60)
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,068	1,146	1,195	1,300	1,552	3,108	2,991
IBNR losses and loss expenses, net of reinsurance	$ 1
Cumulative Number of Claims | claim	7
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,053	989	864	675	459	224	67
2012 | Non-life Run-off | Accident Year - 2015
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	739	739	739	739	1,517	729
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	5
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 739	739	739	739	117	112
2012 | Non-life Run-off | Accident Year - 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	(485)
Incurred losses and allocated loss adjustment expenses, net of reinsurance	445	1,059	1,113	1,266	67
IBNR losses and loss expenses, net of reinsurance	$ 37
Cumulative Number of Claims | claim	2
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 98	98	98	56	3
2012 | Non-life Run-off | Accident Year - 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	100	100	167	75
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	4
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 100	100	43	13
2012 | Non-life Run-off | Accident Year - 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	(59)
Incurred losses and allocated loss adjustment expenses, net of reinsurance	74	154	0
IBNR losses and loss expenses, net of reinsurance	$ 4
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 34	30	0
2012 | Non-life Run-off | Accident Year - 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	(123)
Incurred losses and allocated loss adjustment expenses, net of reinsurance	145	274
IBNR losses and loss expenses, net of reinsurance	$ 11
Cumulative Number of Claims | claim	4
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 36	18
2012 | Non-life Run-off | Accident Year - 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	164
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	3
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 164
2013 | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	562,084
Incurred losses and allocated loss adjustment expenses, net of reinsurance	597,533
IBNR losses and loss expenses, net of reinsurance	$ 22,059
Cumulative Number of Claims | claim	83,886
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 520,791
Liabilities for unpaid losses and allocated LAE, net of reinsurance	76,742
2013 | Non-life Run-off | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	48,207
2013 | Non-life Run-off | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	16,696
2013 | Non-life Run-off | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2013 | Non-life Run-off | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2013 | Non-life Run-off | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2013 | Non-life Run-off | Accident Year - 2010 and Prior
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	320,974
Incurred losses and allocated loss adjustment expenses, net of reinsurance	314,497	313,347	326,851	340,248	356,522	361,812	354,585	349,297
IBNR losses and loss expenses, net of reinsurance	$ 16,353
Cumulative Number of Claims | claim	56,441
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 258,436	249,023	243,755	229,942	222,891	186,762	134,409	74,418
2013 | Non-life Run-off | Accident Year - 2011
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	96,929
Incurred losses and allocated loss adjustment expenses, net of reinsurance	81,616	85,919	86,403	87,913	95,848	100,243	100,482	102,288
IBNR losses and loss expenses, net of reinsurance	$ 2,700
Cumulative Number of Claims | claim	11,185
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 73,282	79,112	77,290	75,055	70,498	63,952	52,455	30,323
2013 | Non-life Run-off | Accident Year - 2012
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	131,119
Incurred losses and allocated loss adjustment expenses, net of reinsurance	105,564	108,025	107,853	110,045	114,772	118,085	121,364	127,323
IBNR losses and loss expenses, net of reinsurance	$ 1,831
Cumulative Number of Claims | claim	10,423
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 98,096	99,781	96,780	92,445	86,916	74,663	59,095	33,361
2013 | Non-life Run-off | Accident Year - 2013
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	13,062
Incurred losses and allocated loss adjustment expenses, net of reinsurance	79,174	80,091	80,036	81,732	85,791	88,920	91,634	90,739
IBNR losses and loss expenses, net of reinsurance	$ 1,073
Cumulative Number of Claims | claim	5,656
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 74,472	74,556	71,487	68,866	62,876	52,638	37,653	$ 17,022
2013 | Non-life Run-off | Accident Year - 2014
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	16,269	16,304	16,225	16,800	3,425	3,714	4,514
IBNR losses and loss expenses, net of reinsurance	$ 55
Cumulative Number of Claims | claim	174
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 16,164	16,123	15,959	15,804	2,256	1,747	993
2013 | Non-life Run-off | Accident Year - 2015
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	237	250	329	982	280	265
IBNR losses and loss expenses, net of reinsurance	$ 42
Cumulative Number of Claims | claim	2
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 191	190	165	112	102	43
2013 | Non-life Run-off | Accident Year - 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	69	69	70	71	103
IBNR losses and loss expenses, net of reinsurance	$ 1
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 67	66	65	64	34
2013 | Non-life Run-off | Accident Year - 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	13	13	13	30
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 13	13	13	9
2013 | Non-life Run-off | Accident Year - 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	18	17	22
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 18	17	13
2013 | Non-life Run-off | Accident Year - 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	15	13
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 15	8
2013 | Non-life Run-off | Accident Year - 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	61
IBNR losses and loss expenses, net of reinsurance	$ 4
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 37
2014 | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	445,106
Incurred losses and allocated loss adjustment expenses, net of reinsurance	565,232
IBNR losses and loss expenses, net of reinsurance	$ 37,800
Cumulative Number of Claims | claim	29,220
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 472,782
Liabilities for unpaid losses and allocated LAE, net of reinsurance	92,450
2014 | Non-life Run-off | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2014 | Non-life Run-off | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	31,610
2014 | Non-life Run-off | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,465
2014 | Non-life Run-off | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	20,942
2014 | Non-life Run-off | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	18,165
2014 | Non-life Run-off | Accident Year - 2010 and Prior
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	142,341
Incurred losses and allocated loss adjustment expenses, net of reinsurance	144,874	145,889	141,058	142,256	155,274	123,973	133,678
IBNR losses and loss expenses, net of reinsurance	$ 6,454
Cumulative Number of Claims | claim	12,014
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 127,622	121,847	120,309	118,857	103,197	82,699	36,509
2014 | Non-life Run-off | Accident Year - 2011
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	74,248
Incurred losses and allocated loss adjustment expenses, net of reinsurance	135,181	139,997	137,806	136,257	134,137	154,394	129,149
IBNR losses and loss expenses, net of reinsurance	$ 10,057
Cumulative Number of Claims | claim	6,228
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 123,364	123,335	120,155	113,701	110,575	109,675	84,031
2014 | Non-life Run-off | Accident Year - 2012
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	141,597
Incurred losses and allocated loss adjustment expenses, net of reinsurance	160,769	162,740	165,821	179,745	187,062	178,577	147,347
IBNR losses and loss expenses, net of reinsurance	$ 10,449
Cumulative Number of Claims | claim	6,393
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 133,026	133,900	130,105	130,001	120,910	90,307	47,495
2014 | Non-life Run-off | Accident Year - 2013
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	86,920
Incurred losses and allocated loss adjustment expenses, net of reinsurance	90,951	88,391	90,387	88,189	83,564	95,125	76,313
IBNR losses and loss expenses, net of reinsurance	$ 8,947
Cumulative Number of Claims | claim	3,173
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 66,225	65,625	65,073	56,941	48,223	40,817	21,752
2014 | Non-life Run-off | Accident Year - 2014
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	7,098	6,954	6,590	7,438	14,506	9,554	13,802
IBNR losses and loss expenses, net of reinsurance	$ 1,708
Cumulative Number of Claims | claim	1,112
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 6,654	6,660	6,147	3,989	3,293	2,504	$ 1,462
2014 | Non-life Run-off | Accident Year - 2015
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	17,090	17,206	18,929	20,741	15,553	33,549
IBNR losses and loss expenses, net of reinsurance	$ 72
Cumulative Number of Claims | claim	183
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 13,473	13,417	13,371	11,566	4,308	1,741
2014 | Non-life Run-off | Accident Year - 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	724	771	4,594	1,108	330
IBNR losses and loss expenses, net of reinsurance	$ 89
Cumulative Number of Claims | claim	45
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 559	561	558	556	20
2014 | Non-life Run-off | Accident Year - 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	8,463	8,200	3,893	5,078
IBNR losses and loss expenses, net of reinsurance	$ 24
Cumulative Number of Claims | claim	37
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,778	1,238	1,541	537
2014 | Non-life Run-off | Accident Year - 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	82	5	6
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	19
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 81	5	5
2014 | Non-life Run-off | Accident Year - 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	10
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
2014 | Non-life Run-off | Accident Year - 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	6
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2015 | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	1,705,544
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,255,339				14,872
IBNR losses and loss expenses, net of reinsurance	$ 117,405
Cumulative Number of Claims | claim	65,779
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 871,122
Liabilities for unpaid losses and allocated LAE, net of reinsurance	384,217
2015 | Non-life Run-off | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	1,382,732
Incurred losses and allocated loss adjustment expenses, net of reinsurance	804,591
IBNR losses and loss expenses, net of reinsurance	$ 56,533
Cumulative Number of Claims | claim	20,677
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 516,938
Liabilities for unpaid losses and allocated LAE, net of reinsurance	287,653
2015 | Non-life Run-off | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	34,704
2015 | Non-life Run-off | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	13,147
2015 | Non-life Run-off | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2015 | Non-life Run-off | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	3,880
2015 | Non-life Run-off | Accident Year - 2010 and Prior
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	1,003,949
Incurred losses and allocated loss adjustment expenses, net of reinsurance	505,379	521,598	564,502	594,466	640,324	933,328
IBNR losses and loss expenses, net of reinsurance	$ 49,461
Cumulative Number of Claims | claim	13,557
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 220,984	195,205	166,983	134,737	83,350	32,819
2015 | Non-life Run-off | Accident Year - 2010 and Prior | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	953,178
Incurred losses and allocated loss adjustment expenses, net of reinsurance	434,422	449,380	490,534	518,764	569,692	868,509
IBNR losses and loss expenses, net of reinsurance	$ 40,504
Cumulative Number of Claims | claim	8,605
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 177,205	155,329	132,025	107,906	65,008	20,630
2015 | Non-life Run-off | Accident Year - 2011
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	124,727
Incurred losses and allocated loss adjustment expenses, net of reinsurance	126,764	128,672	128,155	129,657	131,303	137,429
IBNR losses and loss expenses, net of reinsurance	$ 14,306
Cumulative Number of Claims | claim	5,587
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 105,178	98,000	86,397	71,023	55,115	33,827
2015 | Non-life Run-off | Accident Year - 2011 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	76,789
Incurred losses and allocated loss adjustment expenses, net of reinsurance	65,825	67,741	66,781	68,013	69,009	73,723
IBNR losses and loss expenses, net of reinsurance	$ 3,685
Cumulative Number of Claims | claim	1,241
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 58,420	55,595	50,470	39,635	30,462	16,032
2015 | Non-life Run-off | Accident Year - 2012
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	179,136
Incurred losses and allocated loss adjustment expenses, net of reinsurance	192,426	193,553	194,277	201,017	197,895	187,488
IBNR losses and loss expenses, net of reinsurance	$ 18,110
Cumulative Number of Claims | claim	4,885
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 168,213	158,620	142,358	119,520	94,831	52,728
2015 | Non-life Run-off | Accident Year - 2012 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	120,298
Incurred losses and allocated loss adjustment expenses, net of reinsurance	98,733	99,212	100,187	106,625	108,251	110,007
IBNR losses and loss expenses, net of reinsurance	$ 4,613
Cumulative Number of Claims | claim	1,809
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 91,332	88,369	79,367	66,092	52,851	25,103
2015 | Non-life Run-off | Accident Year - 2013
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	229,590
Incurred losses and allocated loss adjustment expenses, net of reinsurance	184,590	185,101	189,737	199,983	196,582	189,838
IBNR losses and loss expenses, net of reinsurance	$ 13,855
Cumulative Number of Claims | claim	4,699
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 164,215	159,767	145,788	120,509	89,930	46,761
2015 | Non-life Run-off | Accident Year - 2013 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	146,237
Incurred losses and allocated loss adjustment expenses, net of reinsurance	113,414	112,677	113,056	121,010	122,238	124,726
IBNR losses and loss expenses, net of reinsurance	$ 5,595
Cumulative Number of Claims | claim	2,386
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 104,265	100,890	91,559	75,065	55,675	27,737
2015 | Non-life Run-off | Accident Year - 2014
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	144,392
Incurred losses and allocated loss adjustment expenses, net of reinsurance	147,567	152,478	137,541	142,937	137,668	143,193
IBNR losses and loss expenses, net of reinsurance	$ 7,413
Cumulative Number of Claims | claim	7,783
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 133,094	125,619	109,451	91,016	64,475	30,747
2015 | Non-life Run-off | Accident Year - 2014 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	82,141
Incurred losses and allocated loss adjustment expenses, net of reinsurance	80,307	78,948	78,389	83,095	82,038	86,852
IBNR losses and loss expenses, net of reinsurance	$ 1,513
Cumulative Number of Claims | claim	3,686
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 75,781	72,696	65,561	53,308	38,051	17,824
2015 | Non-life Run-off | Accident Year - 2015
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	23,750
Incurred losses and allocated loss adjustment expenses, net of reinsurance	73,256	69,465	64,974	66,152	69,322	70,276
IBNR losses and loss expenses, net of reinsurance	$ 6,959
Cumulative Number of Claims | claim	10,997
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 63,181	59,963	51,994	46,668	38,709	20,653
2015 | Non-life Run-off | Accident Year - 2015 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	4,089
Incurred losses and allocated loss adjustment expenses, net of reinsurance	11,337	11,309	12,295	13,488	12,623	18,647
IBNR losses and loss expenses, net of reinsurance	$ 557
Cumulative Number of Claims | claim	2,900
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 9,461	9,248	9,169	7,917	5,672	$ 3,034
2015 | Non-life Run-off | Accident Year - 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	12,868	14,576	13,440	13,141
IBNR losses and loss expenses, net of reinsurance	$ 2,178
Cumulative Number of Claims | claim	14,283
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 10,321	9,861	8,687	7,371	5,603
2015 | Non-life Run-off | Accident Year - 2016 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	514	536	583	955	873
IBNR losses and loss expenses, net of reinsurance	$ 52
Cumulative Number of Claims | claim	38
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 452	447	417	363	134
2015 | Non-life Run-off | Accident Year - 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	6,860	5,277	4,527	4,095
IBNR losses and loss expenses, net of reinsurance	$ 345
Cumulative Number of Claims | claim	3,534
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 5,047	4,767	3,925	2,321
2015 | Non-life Run-off | Accident Year - 2017 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	33	41	61	358
IBNR losses and loss expenses, net of reinsurance	$ 13
Cumulative Number of Claims | claim	10
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 19	18	10	2
2015 | Non-life Run-off | Accident Year - 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,805	1,889	3,055
IBNR losses and loss expenses, net of reinsurance	$ 985
Cumulative Number of Claims | claim	400
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 820	862	567
2015 | Non-life Run-off | Accident Year - 2018 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	3	5	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 2	1	0
2015 | Non-life Run-off | Accident Year - 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,873	1,838
IBNR losses and loss expenses, net of reinsurance	$ 1,831
Cumulative Number of Claims | claim	51
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 65	45
2015 | Non-life Run-off | Accident Year - 2019 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	3	1
IBNR losses and loss expenses, net of reinsurance	$ 1
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1	0
2015 | Non-life Run-off | Accident Year - 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,951
IBNR losses and loss expenses, net of reinsurance	$ 1,962
Cumulative Number of Claims | claim	3
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 4
2015 | Non-life Run-off | Accident Year - 2020 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2016 | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	1,336,710
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,394,730
IBNR losses and loss expenses, net of reinsurance	$ 310,050
Cumulative Number of Claims | claim	26,303
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 559,341
Liabilities for unpaid losses and allocated LAE, net of reinsurance	835,389
2016 | Non-life Run-off | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	465,907
Incurred losses and allocated loss adjustment expenses, net of reinsurance	394,837
IBNR losses and loss expenses, net of reinsurance	$ 21,409
Cumulative Number of Claims | claim	10,533
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 175,680
Liabilities for unpaid losses and allocated LAE, net of reinsurance	219,157
2016 | Non-life Run-off | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	3,727
2016 | Non-life Run-off | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2016 | Non-life Run-off | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	76,314
2016 | Non-life Run-off | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	465
2016 | Non-life Run-off | Accident Year - 2010 and Prior
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	1,304,938
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,361,353	1,322,161	1,321,289	1,346,575	1,316,544
IBNR losses and loss expenses, net of reinsurance	$ 305,042
Cumulative Number of Claims | claim	24,449
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 536,987	445,770	331,218	222,703	101,098
2016 | Non-life Run-off | Accident Year - 2010 and Prior | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	437,457
Incurred losses and allocated loss adjustment expenses, net of reinsurance	367,109	382,446	391,476	403,319	437,805
IBNR losses and loss expenses, net of reinsurance	$ 19,015
Cumulative Number of Claims | claim	9,452
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 155,433	127,081	90,599	65,264	35,518
2016 | Non-life Run-off | Accident Year - 2011
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	17,291
Incurred losses and allocated loss adjustment expenses, net of reinsurance	18,609	18,829	19,754	19,920	17,291
IBNR losses and loss expenses, net of reinsurance	$ 2,266
Cumulative Number of Claims | claim	861
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 13,098	9,691	8,218	6,647	2,758
2016 | Non-life Run-off | Accident Year - 2011 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	15,376
Incurred losses and allocated loss adjustment expenses, net of reinsurance	16,472	16,327	16,501	16,399	15,376
IBNR losses and loss expenses, net of reinsurance	$ 1,374
Cumulative Number of Claims | claim	469
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 12,130	8,756	7,305	5,871	2,631
2016 | Non-life Run-off | Accident Year - 2012
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	13,717
Incurred losses and allocated loss adjustment expenses, net of reinsurance	13,037	12,717	14,765	17,020	13,717
IBNR losses and loss expenses, net of reinsurance	$ 1,829
Cumulative Number of Claims | claim	809
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 8,492	7,587	6,461	5,206	2,734
2016 | Non-life Run-off | Accident Year - 2012 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	13,074
Incurred losses and allocated loss adjustment expenses, net of reinsurance	11,256	11,379	13,276	15,465	13,074
IBNR losses and loss expenses, net of reinsurance	$ 1,020
Cumulative Number of Claims | claim	612
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 8,117	7,382	6,247	5,028	2,638
2016 | Non-life Run-off | Accident Year - 2013
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	373
Incurred losses and allocated loss adjustment expenses, net of reinsurance	914	1,120	1,237	1,312	373
IBNR losses and loss expenses, net of reinsurance	$ 603
Cumulative Number of Claims | claim	127
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 301	285	278	191	145
2016 | Non-life Run-off | Accident Year - 2013 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0	0	0
2016 | Non-life Run-off | Accident Year - 2014
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	391
Incurred losses and allocated loss adjustment expenses, net of reinsurance	817	869	1,056	1,380	391
IBNR losses and loss expenses, net of reinsurance	$ 310
Cumulative Number of Claims | claim	57
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 463	366	284	207	178
2016 | Non-life Run-off | Accident Year - 2014 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0	0	0
2016 | Non-life Run-off | Accident Year - 2015
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0	0	0
2016 | Non-life Run-off | Accident Year - 2015 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0	0	0
2016 | Non-life Run-off | Accident Year - 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0	0	0
2016 | Non-life Run-off | Accident Year - 2016 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0	0	$ 0
2016 | Non-life Run-off | Accident Year - 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0	0
2016 | Non-life Run-off | Accident Year - 2017 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0	0
2016 | Non-life Run-off | Accident Year - 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0
2016 | Non-life Run-off | Accident Year - 2018 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0
2016 | Non-life Run-off | Accident Year - 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
2016 | Non-life Run-off | Accident Year - 2019 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
2016 | Non-life Run-off | Accident Year - 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2016 | Non-life Run-off | Accident Year - 2020 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2017 | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	1,669,704
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,457,941
IBNR losses and loss expenses, net of reinsurance	$ 763,550
Cumulative Number of Claims | claim	31,627
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 415,687
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,042,254
2017 | Non-life Run-off | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	53,659
2017 | Non-life Run-off | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	44,551
2017 | Non-life Run-off | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	3,710
2017 | Non-life Run-off | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	0
2017 | Non-life Run-off | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	(114)
2017 | Non-life Run-off | Accident Year - 2010 and Prior
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	1,507,609
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,349,226	1,364,113	1,351,451	1,433,301
IBNR losses and loss expenses, net of reinsurance	$ 749,197
Cumulative Number of Claims | claim	31,566
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 334,586	257,071	175,630	85,514
2017 | Non-life Run-off | Accident Year - 2011
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	40,743
Incurred losses and allocated loss adjustment expenses, net of reinsurance	26,942	27,316	25,389	29,274
IBNR losses and loss expenses, net of reinsurance	$ 5,834
Cumulative Number of Claims | claim	8
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 15,407	12,971	9,257	4,125
2017 | Non-life Run-off | Accident Year - 2012
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	43,653
Incurred losses and allocated loss adjustment expenses, net of reinsurance	28,485	29,456	31,238	35,470
IBNR losses and loss expenses, net of reinsurance	$ 3,744
Cumulative Number of Claims | claim	10
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 21,076	18,605	15,372	10,348
2017 | Non-life Run-off | Accident Year - 2013
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	35,671
Incurred losses and allocated loss adjustment expenses, net of reinsurance	29,829	24,707	28,139	30,338
IBNR losses and loss expenses, net of reinsurance	$ 1,860
Cumulative Number of Claims | claim	11
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 25,832	21,280	15,714	9,509
2017 | Non-life Run-off | Accident Year - 2014
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	32,858
Incurred losses and allocated loss adjustment expenses, net of reinsurance	16,342	15,996	16,984	20,315
IBNR losses and loss expenses, net of reinsurance	$ 2,287
Cumulative Number of Claims | claim	20
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 12,668	11,559	8,986	6,482
2017 | Non-life Run-off | Accident Year - 2015
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	8,808
Incurred losses and allocated loss adjustment expenses, net of reinsurance	6,043	6,295	7,002	6,494
IBNR losses and loss expenses, net of reinsurance	$ 234
Cumulative Number of Claims | claim	8
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 5,582	4,687	3,720	1,361
2017 | Non-life Run-off | Accident Year - 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	362
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,074	919	126	(4)
IBNR losses and loss expenses, net of reinsurance	$ 394
Cumulative Number of Claims | claim	3
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 536	434	66	(56)
2017 | Non-life Run-off | Accident Year - 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0	174
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0	$ 4
2017 | Non-life Run-off | Accident Year - 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0
2017 | Non-life Run-off | Accident Year - 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
2017 | Non-life Run-off | Accident Year - 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2018 | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	2,812,443
Incurred losses and allocated loss adjustment expenses, net of reinsurance	2,669,540
IBNR losses and loss expenses, net of reinsurance	$ 387,647
Cumulative Number of Claims | claim	325,135
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,341,680
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,327,860
2018 | Non-life Run-off | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	494,569
Incurred losses and allocated loss adjustment expenses, net of reinsurance	471,501
IBNR losses and loss expenses, net of reinsurance	$ 165,997
Cumulative Number of Claims | claim	9,804
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 148,764
Liabilities for unpaid losses and allocated LAE, net of reinsurance	322,737
2018 | Non-life Run-off | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	480,523
Incurred losses and allocated loss adjustment expenses, net of reinsurance	463,978
IBNR losses and loss expenses, net of reinsurance	$ 69,218
Cumulative Number of Claims | claim	59,087
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 235,559
Liabilities for unpaid losses and allocated LAE, net of reinsurance	228,419
2018 | Non-life Run-off | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	862,420
Incurred losses and allocated loss adjustment expenses, net of reinsurance	794,204
IBNR losses and loss expenses, net of reinsurance	$ 89,741
Cumulative Number of Claims | claim	16,116
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 533,407
Liabilities for unpaid losses and allocated LAE, net of reinsurance	260,797
2018 | Non-life Run-off | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	535,984
Incurred losses and allocated loss adjustment expenses, net of reinsurance	546,375
IBNR losses and loss expenses, net of reinsurance	$ 41,085
Cumulative Number of Claims | claim	74,587
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 214,699
Liabilities for unpaid losses and allocated LAE, net of reinsurance	331,676
2018 | Non-life Run-off | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	47,270
2018 | Non-life Run-off | Accident Year - 2010 and Prior
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	662,009
Incurred losses and allocated loss adjustment expenses, net of reinsurance	409,505	476,164	497,101
IBNR losses and loss expenses, net of reinsurance	$ 50,970
Cumulative Number of Claims | claim	223,572
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 81,554	86,132	50,515
2018 | Non-life Run-off | Accident Year - 2010 and Prior | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	131,873
Incurred losses and allocated loss adjustment expenses, net of reinsurance	131,775	129,280	122,831
IBNR losses and loss expenses, net of reinsurance	$ 39,843
Cumulative Number of Claims | claim	2,098
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 21,726	11,788	604
2018 | Non-life Run-off | Accident Year - 2010 and Prior | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	130,049
Incurred losses and allocated loss adjustment expenses, net of reinsurance	67,933	70,937	74,102
IBNR losses and loss expenses, net of reinsurance	$ 4,827
Cumulative Number of Claims | claim	47,893
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 29,840	18,817	9,164
2018 | Non-life Run-off | Accident Year - 2010 and Prior | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	43,818
Incurred losses and allocated loss adjustment expenses, net of reinsurance	33,230	30,036	31,489
IBNR losses and loss expenses, net of reinsurance	$ 2,599
Cumulative Number of Claims | claim	1,323
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 16,655	13,722	7,460
2018 | Non-life Run-off | Accident Year - 2010 and Prior | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	236,568
Incurred losses and allocated loss adjustment expenses, net of reinsurance	143,585	147,383	137,394
IBNR losses and loss expenses, net of reinsurance	$ (3,639)
Cumulative Number of Claims | claim	56,674
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 28,528	54,157	29,359
2018 | Non-life Run-off | Accident Year - 2011
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	164,556
Incurred losses and allocated loss adjustment expenses, net of reinsurance	147,796	150,388	150,408
IBNR losses and loss expenses, net of reinsurance	$ 16,240
Cumulative Number of Claims | claim	14,072
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 65,522	53,151	26,236
2018 | Non-life Run-off | Accident Year - 2011 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	29,897
Incurred losses and allocated loss adjustment expenses, net of reinsurance	27,203	29,981	28,685
IBNR losses and loss expenses, net of reinsurance	$ 9,067
Cumulative Number of Claims | claim	401
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 9,418	5,592	2,281
2018 | Non-life Run-off | Accident Year - 2011 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	18,044
Incurred losses and allocated loss adjustment expenses, net of reinsurance	15,855	16,650	16,554
IBNR losses and loss expenses, net of reinsurance	$ 151
Cumulative Number of Claims | claim	1,421
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 11,018	7,115	2,349
2018 | Non-life Run-off | Accident Year - 2011 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	48,231
Incurred losses and allocated loss adjustment expenses, net of reinsurance	36,301	37,707	38,092
IBNR losses and loss expenses, net of reinsurance	$ 2,031
Cumulative Number of Claims | claim	1,239
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 15,464	12,980	6,060
2018 | Non-life Run-off | Accident Year - 2011 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	46,512
Incurred losses and allocated loss adjustment expenses, net of reinsurance	51,600	48,884	52,553
IBNR losses and loss expenses, net of reinsurance	$ 3,185
Cumulative Number of Claims | claim	3,762
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 22,250	20,017	13,123
2018 | Non-life Run-off | Accident Year - 2012
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	232,116
Incurred losses and allocated loss adjustment expenses, net of reinsurance	225,528	224,959	224,955
IBNR losses and loss expenses, net of reinsurance	$ 29,903
Cumulative Number of Claims | claim	14,382
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 106,297	81,356	31,772
2018 | Non-life Run-off | Accident Year - 2012 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	28,749
Incurred losses and allocated loss adjustment expenses, net of reinsurance	26,833	27,676	29,181
IBNR losses and loss expenses, net of reinsurance	$ 10,597
Cumulative Number of Claims | claim	468
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 7,941	5,508	516
2018 | Non-life Run-off | Accident Year - 2012 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	37,454
Incurred losses and allocated loss adjustment expenses, net of reinsurance	29,760	29,123	33,433
IBNR losses and loss expenses, net of reinsurance	$ 3,270
Cumulative Number of Claims | claim	1,593
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 14,383	11,453	1,281
2018 | Non-life Run-off | Accident Year - 2012 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	65,427
Incurred losses and allocated loss adjustment expenses, net of reinsurance	59,276	63,786	58,006
IBNR losses and loss expenses, net of reinsurance	$ 5,862
Cumulative Number of Claims | claim	1,641
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 31,136	24,433	12,380
2018 | Non-life Run-off | Accident Year - 2012 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	57,937
Incurred losses and allocated loss adjustment expenses, net of reinsurance	74,884	69,641	70,636
IBNR losses and loss expenses, net of reinsurance	$ 4,399
Cumulative Number of Claims | claim	3,285
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 33,794	23,237	16,382
2018 | Non-life Run-off | Accident Year - 2013
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	272,732
Incurred losses and allocated loss adjustment expenses, net of reinsurance	250,013	268,237	274,377
IBNR losses and loss expenses, net of reinsurance	$ 35,175
Cumulative Number of Claims | claim	16,126
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 133,398	96,968	41,544
2018 | Non-life Run-off | Accident Year - 2013 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	38,029
Incurred losses and allocated loss adjustment expenses, net of reinsurance	35,212	38,093	38,554
IBNR losses and loss expenses, net of reinsurance	$ 13,243
Cumulative Number of Claims | claim	869
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 12,280	7,773	1,525
2018 | Non-life Run-off | Accident Year - 2013 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	43,301
Incurred losses and allocated loss adjustment expenses, net of reinsurance	46,999	46,596	56,092
IBNR losses and loss expenses, net of reinsurance	$ 4,352
Cumulative Number of Claims | claim	1,596
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 27,717	19,938	10,404
2018 | Non-life Run-off | Accident Year - 2013 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	78,456
Incurred losses and allocated loss adjustment expenses, net of reinsurance	55,345	65,012	71,276
IBNR losses and loss expenses, net of reinsurance	$ 5,744
Cumulative Number of Claims | claim	683
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 35,186	29,311	11,114
2018 | Non-life Run-off | Accident Year - 2013 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	59,457
Incurred losses and allocated loss adjustment expenses, net of reinsurance	76,291	78,933	63,284
IBNR losses and loss expenses, net of reinsurance	$ 10,543
Cumulative Number of Claims | claim	3,257
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 34,269	21,919	10,987
2018 | Non-life Run-off | Accident Year - 2014
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	419,593
Incurred losses and allocated loss adjustment expenses, net of reinsurance	415,829	439,396	462,858
IBNR losses and loss expenses, net of reinsurance	$ 38,688
Cumulative Number of Claims | claim	19,463
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 235,787	188,721	90,689
2018 | Non-life Run-off | Accident Year - 2014 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	65,049
Incurred losses and allocated loss adjustment expenses, net of reinsurance	52,797	57,163	66,346
IBNR losses and loss expenses, net of reinsurance	$ 17,605
Cumulative Number of Claims | claim	1,345
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 21,380	14,687	3,260
2018 | Non-life Run-off | Accident Year - 2014 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	66,562
Incurred losses and allocated loss adjustment expenses, net of reinsurance	68,535	74,947	80,896
IBNR losses and loss expenses, net of reinsurance	$ 5,802
Cumulative Number of Claims | claim	2,291
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 41,899	27,833	13,766
2018 | Non-life Run-off | Accident Year - 2014 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	116,677
Incurred losses and allocated loss adjustment expenses, net of reinsurance	84,459	90,902	103,761
IBNR losses and loss expenses, net of reinsurance	$ 5,243
Cumulative Number of Claims | claim	1,260
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 60,254	49,089	22,393
2018 | Non-life Run-off | Accident Year - 2014 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	88,173
Incurred losses and allocated loss adjustment expenses, net of reinsurance	114,621	107,411	111,193
IBNR losses and loss expenses, net of reinsurance	$ 11,523
Cumulative Number of Claims | claim	3,619
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 61,024	39,601	22,734
2018 | Non-life Run-off | Accident Year - 2015
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	365,429
Incurred losses and allocated loss adjustment expenses, net of reinsurance	496,187	480,093	483,489
IBNR losses and loss expenses, net of reinsurance	$ 62,476
Cumulative Number of Claims | claim	24,768
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 269,559	199,373	95,688
2018 | Non-life Run-off | Accident Year - 2015 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	38,851
Incurred losses and allocated loss adjustment expenses, net of reinsurance	33,253	35,235	39,379
IBNR losses and loss expenses, net of reinsurance	$ 13,026
Cumulative Number of Claims | claim	1,464
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 9,844	4,355	1,403
2018 | Non-life Run-off | Accident Year - 2015 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	79,191
Incurred losses and allocated loss adjustment expenses, net of reinsurance	109,694	104,790	94,124
IBNR losses and loss expenses, net of reinsurance	$ 14,188
Cumulative Number of Claims | claim	3,594
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 49,860	31,535	15,494
2018 | Non-life Run-off | Accident Year - 2015 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	135,855
Incurred losses and allocated loss adjustment expenses, net of reinsurance	132,165	132,167	133,493
IBNR losses and loss expenses, net of reinsurance	$ 15,246
Cumulative Number of Claims | claim	1,510
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 84,976	61,928	21,712
2018 | Non-life Run-off | Accident Year - 2015 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	47,337
Incurred losses and allocated loss adjustment expenses, net of reinsurance	85,394	81,272	100,975
IBNR losses and loss expenses, net of reinsurance	$ 15,074
Cumulative Number of Claims | claim	3,990
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 34,834	26,595	14,245
2018 | Non-life Run-off | Accident Year - 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	173,309
Incurred losses and allocated loss adjustment expenses, net of reinsurance	169,872	178,061	175,428
IBNR losses and loss expenses, net of reinsurance	$ 36,090
Cumulative Number of Claims | claim	2,026
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 93,705	63,982	6,854
2018 | Non-life Run-off | Accident Year - 2016 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	44,686
Incurred losses and allocated loss adjustment expenses, net of reinsurance	37,714	38,945	44,686
IBNR losses and loss expenses, net of reinsurance	$ 15,857
Cumulative Number of Claims | claim	892
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 7,176	3,666	0
2018 | Non-life Run-off | Accident Year - 2016 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	28,825
Incurred losses and allocated loss adjustment expenses, net of reinsurance	36,684	36,585	28,825
IBNR losses and loss expenses, net of reinsurance	$ 10,075
Cumulative Number of Claims | claim	253
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 18,916	14,109	0
2018 | Non-life Run-off | Accident Year - 2016 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	93,164
Incurred losses and allocated loss adjustment expenses, net of reinsurance	91,600	97,040	95,283
IBNR losses and loss expenses, net of reinsurance	$ 9,824
Cumulative Number of Claims | claim	732
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 65,287	43,851	6,854
2018 | Non-life Run-off | Accident Year - 2016 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0
2018 | Non-life Run-off | Accident Year - 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	207,040
Incurred losses and allocated loss adjustment expenses, net of reinsurance	204,490	205,466	207,190
IBNR losses and loss expenses, net of reinsurance	$ 55,056
Cumulative Number of Claims | claim	4,163
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 113,770	72,800	56
2018 | Non-life Run-off | Accident Year - 2017 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	52,360
Incurred losses and allocated loss adjustment expenses, net of reinsurance	45,529	49,156	52,360
IBNR losses and loss expenses, net of reinsurance	$ 23,004
Cumulative Number of Claims | claim	998
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 9,088	5,900	0
2018 | Non-life Run-off | Accident Year - 2017 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	37,209
Incurred losses and allocated loss adjustment expenses, net of reinsurance	43,174	41,664	37,209
IBNR losses and loss expenses, net of reinsurance	$ 14,554
Cumulative Number of Claims | claim	230
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 21,130	11,048	0
2018 | Non-life Run-off | Accident Year - 2017 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	100,321
Incurred losses and allocated loss adjustment expenses, net of reinsurance	102,038	99,135	100,471
IBNR losses and loss expenses, net of reinsurance	$ 16,628
Cumulative Number of Claims | claim	2,797
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 73,440	48,661	56
2018 | Non-life Run-off | Accident Year - 2017 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	0
2018 | Non-life Run-off | Accident Year - 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	315,659
Incurred losses and allocated loss adjustment expenses, net of reinsurance	282,279	285,038	315,659
IBNR losses and loss expenses, net of reinsurance	$ 53,287
Cumulative Number of Claims | claim	4,929
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 191,442	139,815	0
2018 | Non-life Run-off | Accident Year - 2018 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	65,075
Incurred losses and allocated loss adjustment expenses, net of reinsurance	59,768	60,923	65,075
IBNR losses and loss expenses, net of reinsurance	$ 19,310
Cumulative Number of Claims | claim	886
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 34,317	28,725	0
2018 | Non-life Run-off | Accident Year - 2018 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	39,888
Incurred losses and allocated loss adjustment expenses, net of reinsurance	39,157	40,753	39,888
IBNR losses and loss expenses, net of reinsurance	$ 11,605
Cumulative Number of Claims | claim	182
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 17,455	8,879	0
2018 | Non-life Run-off | Accident Year - 2018 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	180,471
Incurred losses and allocated loss adjustment expenses, net of reinsurance	160,143	157,556	180,471
IBNR losses and loss expenses, net of reinsurance	$ 21,609
Cumulative Number of Claims | claim	3,731
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 120,041	86,861	0
2018 | Non-life Run-off | Accident Year - 2018 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0	$ 0
2018 | Non-life Run-off | Accident Year - 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	68,041	68,271
IBNR losses and loss expenses, net of reinsurance	$ 9,762
Cumulative Number of Claims | claim	1,634
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 50,646	39,099
2018 | Non-life Run-off | Accident Year - 2019 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	21,417	20,889
IBNR losses and loss expenses, net of reinsurance	$ 4,445
Cumulative Number of Claims | claim	383
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 15,594	13,483
2018 | Non-life Run-off | Accident Year - 2019 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	6,187	6,767
IBNR losses and loss expenses, net of reinsurance	$ 394
Cumulative Number of Claims | claim	34
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 3,341	2,373
2018 | Non-life Run-off | Accident Year - 2019 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	39,647	39,757
IBNR losses and loss expenses, net of reinsurance	$ 4,955
Cumulative Number of Claims | claim	1,200
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 30,968	22,687
2018 | Non-life Run-off | Accident Year - 2019 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
2018 | Non-life Run-off | Accident Year - 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2018 | Non-life Run-off | Accident Year - 2020 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2018 | Non-life Run-off | Accident Year - 2020 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2018 | Non-life Run-off | Accident Year - 2020 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2018 | Non-life Run-off | Accident Year - 2020 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2019 | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	1,736,814
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,757,670
IBNR losses and loss expenses, net of reinsurance	$ 868,570
Cumulative Number of Claims | claim	194,706
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 418,235
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,339,435
2019 | Non-life Run-off | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	413,202
Incurred losses and allocated loss adjustment expenses, net of reinsurance	410,824
IBNR losses and loss expenses, net of reinsurance	$ 378,727
Cumulative Number of Claims | claim	28,720
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 23,386
Liabilities for unpaid losses and allocated LAE, net of reinsurance	387,438
2019 | Non-life Run-off | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	285,332
Incurred losses and allocated loss adjustment expenses, net of reinsurance	261,468
IBNR losses and loss expenses, net of reinsurance	$ 167,417
Cumulative Number of Claims | claim	10,378
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 42,473
Liabilities for unpaid losses and allocated LAE, net of reinsurance	218,995
2019 | Non-life Run-off | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	17,899
2019 | Non-life Run-off | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	130,906
2019 | Non-life Run-off | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	39,286
2019 | Non-life Run-off | Accident Year - 2010 and Prior
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	652,608
Incurred losses and allocated loss adjustment expenses, net of reinsurance	628,495	630,171
IBNR losses and loss expenses, net of reinsurance	$ 272,910
Cumulative Number of Claims | claim	74,742
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 106,195	26,817
2019 | Non-life Run-off | Accident Year - 2010 and Prior | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	5,860
Incurred losses and allocated loss adjustment expenses, net of reinsurance	4,551	4,420
IBNR losses and loss expenses, net of reinsurance	$ 1,938
Cumulative Number of Claims | claim	9,869
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 696	607
2019 | Non-life Run-off | Accident Year - 2010 and Prior | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	12,765
Incurred losses and allocated loss adjustment expenses, net of reinsurance	9,994	9,788
IBNR losses and loss expenses, net of reinsurance	$ 1,620
Cumulative Number of Claims | claim	1,424
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 2,894	2,230
2019 | Non-life Run-off | Accident Year - 2011
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	49,873
Incurred losses and allocated loss adjustment expenses, net of reinsurance	35,876	40,554
IBNR losses and loss expenses, net of reinsurance	$ 8,773
Cumulative Number of Claims | claim	15,218
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 8,100	4,786
2019 | Non-life Run-off | Accident Year - 2011 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	2,474
Incurred losses and allocated loss adjustment expenses, net of reinsurance	2,409	2,410
IBNR losses and loss expenses, net of reinsurance	$ 2,342
Cumulative Number of Claims | claim	1,082
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 23	22
2019 | Non-life Run-off | Accident Year - 2011 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	12,321
Incurred losses and allocated loss adjustment expenses, net of reinsurance	7,979	9,490
IBNR losses and loss expenses, net of reinsurance	$ 3,587
Cumulative Number of Claims | claim	796
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,869	810
2019 | Non-life Run-off | Accident Year - 2012
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	73,098
Incurred losses and allocated loss adjustment expenses, net of reinsurance	49,349	54,301
IBNR losses and loss expenses, net of reinsurance	$ 12,905
Cumulative Number of Claims | claim	12,329
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 9,565	6,886
2019 | Non-life Run-off | Accident Year - 2012 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	6,280
Incurred losses and allocated loss adjustment expenses, net of reinsurance	6,176	6,176
IBNR losses and loss expenses, net of reinsurance	$ 6,991
Cumulative Number of Claims | claim	1,640
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 63	22
2019 | Non-life Run-off | Accident Year - 2012 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	18,107
Incurred losses and allocated loss adjustment expenses, net of reinsurance	13,786	14,471
IBNR losses and loss expenses, net of reinsurance	$ 8,214
Cumulative Number of Claims | claim	1,165
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 6,604	3,326
2019 | Non-life Run-off | Accident Year - 2013
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	112,031
Incurred losses and allocated loss adjustment expenses, net of reinsurance	88,066	93,213
IBNR losses and loss expenses, net of reinsurance	$ 29,931
Cumulative Number of Claims | claim	14,952
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 20,906	13,540
2019 | Non-life Run-off | Accident Year - 2013 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	16,738
Incurred losses and allocated loss adjustment expenses, net of reinsurance	15,980	18,339
IBNR losses and loss expenses, net of reinsurance	$ 14,415
Cumulative Number of Claims | claim	2,897
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 572	458
2019 | Non-life Run-off | Accident Year - 2013 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	23,750
Incurred losses and allocated loss adjustment expenses, net of reinsurance	20,960	18,230
IBNR losses and loss expenses, net of reinsurance	$ 8,897
Cumulative Number of Claims | claim	313
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 5,813	3,499
2019 | Non-life Run-off | Accident Year - 2014
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	137,324
Incurred losses and allocated loss adjustment expenses, net of reinsurance	127,704	137,478
IBNR losses and loss expenses, net of reinsurance	$ 53,814
Cumulative Number of Claims | claim	17,624
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 47,310	28,188
2019 | Non-life Run-off | Accident Year - 2014 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	35,023
Incurred losses and allocated loss adjustment expenses, net of reinsurance	35,556	35,426
IBNR losses and loss expenses, net of reinsurance	$ 31,501
Cumulative Number of Claims | claim	3,410
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 3,443	3,080
2019 | Non-life Run-off | Accident Year - 2014 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	33,767
Incurred losses and allocated loss adjustment expenses, net of reinsurance	29,341	31,181
IBNR losses and loss expenses, net of reinsurance	$ 16,377
Cumulative Number of Claims | claim	905
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 8,155	3,878
2019 | Non-life Run-off | Accident Year - 2015
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	179,651
Incurred losses and allocated loss adjustment expenses, net of reinsurance	196,007	188,833
IBNR losses and loss expenses, net of reinsurance	$ 80,816
Cumulative Number of Claims | claim	25,081
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 63,994	33,417
2019 | Non-life Run-off | Accident Year - 2015 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	57,194
Incurred losses and allocated loss adjustment expenses, net of reinsurance	57,314	56,171
IBNR losses and loss expenses, net of reinsurance	$ 48,840
Cumulative Number of Claims | claim	4,802
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 6,325	3,549
2019 | Non-life Run-off | Accident Year - 2015 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	58,818
Incurred losses and allocated loss adjustment expenses, net of reinsurance	41,158	45,936
IBNR losses and loss expenses, net of reinsurance	$ 18,055
Cumulative Number of Claims | claim	2,003
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 5,121	4,421
2019 | Non-life Run-off | Accident Year - 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	253,099
Incurred losses and allocated loss adjustment expenses, net of reinsurance	260,473	295,011
IBNR losses and loss expenses, net of reinsurance	$ 118,653
Cumulative Number of Claims | claim	32,057
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 84,592	56,125
2019 | Non-life Run-off | Accident Year - 2016 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	87,702
Incurred losses and allocated loss adjustment expenses, net of reinsurance	84,862	85,530
IBNR losses and loss expenses, net of reinsurance	$ 70,769
Cumulative Number of Claims | claim	4,829
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 12,137	7,337
2019 | Non-life Run-off | Accident Year - 2016 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	48,606
Incurred losses and allocated loss adjustment expenses, net of reinsurance	58,061	64,159
IBNR losses and loss expenses, net of reinsurance	$ 32,692
Cumulative Number of Claims | claim	3,134
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 10,723	4,894
2019 | Non-life Run-off | Accident Year - 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	116,386
Incurred losses and allocated loss adjustment expenses, net of reinsurance	116,386	116,386
IBNR losses and loss expenses, net of reinsurance	$ 116,386
Cumulative Number of Claims | claim	2
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
2019 | Non-life Run-off | Accident Year - 2017 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	84,197
Incurred losses and allocated loss adjustment expenses, net of reinsurance	84,197	84,197
IBNR losses and loss expenses, net of reinsurance	$ 84,197
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
2019 | Non-life Run-off | Accident Year - 2017 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	32,188
Incurred losses and allocated loss adjustment expenses, net of reinsurance	32,188	32,188
IBNR losses and loss expenses, net of reinsurance	$ 32,188
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
2019 | Non-life Run-off | Accident Year - 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	162,744
Incurred losses and allocated loss adjustment expenses, net of reinsurance	162,744	162,744
IBNR losses and loss expenses, net of reinsurance	$ 162,744
Cumulative Number of Claims | claim	2
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
2019 | Non-life Run-off | Accident Year - 2018 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	117,734
Incurred losses and allocated loss adjustment expenses, net of reinsurance	117,734	117,734
IBNR losses and loss expenses, net of reinsurance	$ 117,734
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
2019 | Non-life Run-off | Accident Year - 2018 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	45,010
Incurred losses and allocated loss adjustment expenses, net of reinsurance	45,010	45,010
IBNR losses and loss expenses, net of reinsurance	$ 45,010
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
2019 | Non-life Run-off | Accident Year - 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	64,595	54,571
IBNR losses and loss expenses, net of reinsurance	$ 6,155
Cumulative Number of Claims | claim	1,679
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 55,912	25,595
2019 | Non-life Run-off | Accident Year - 2019 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0	0
2019 | Non-life Run-off | Accident Year - 2019 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,873	1,750
IBNR losses and loss expenses, net of reinsurance	$ 510
Cumulative Number of Claims | claim	225
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 841	$ 0
2019 | Non-life Run-off | Accident Year - 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	27,975
IBNR losses and loss expenses, net of reinsurance	$ 5,483
Cumulative Number of Claims | claim	1,020
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 21,661
2019 | Non-life Run-off | Accident Year - 2020 | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	2,045
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	189
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 127
2019 | Non-life Run-off | Accident Year - 2020 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,118
IBNR losses and loss expenses, net of reinsurance	$ 267
Cumulative Number of Claims | claim	411
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 453
2020 | Non-life Run-off
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	2,142,407
Incurred losses and allocated loss adjustment expenses, net of reinsurance	2,217,299
IBNR losses and loss expenses, net of reinsurance	$ 1,455,605
Cumulative Number of Claims | claim	9,408
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 253,537
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,963,762
2020 | Non-life Run-off | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	199,864
2020 | Non-life Run-off | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	1,127,100
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,114,900
IBNR losses and loss expenses, net of reinsurance	$ 924,349
Cumulative Number of Claims | claim	2,587
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 36,992
Liabilities for unpaid losses and allocated LAE, net of reinsurance	1,077,908
2020 | Non-life Run-off | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	455,000
Incurred losses and allocated loss adjustment expenses, net of reinsurance	628,296
IBNR losses and loss expenses, net of reinsurance	$ 187,284
Cumulative Number of Claims | claim	3,543
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 205,975
Liabilities for unpaid losses and allocated LAE, net of reinsurance	422,321
2020 | Non-life Run-off | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	235,979
Incurred losses and allocated loss adjustment expenses, net of reinsurance	235,994
IBNR losses and loss expenses, net of reinsurance	$ 217,024
Cumulative Number of Claims | claim	401
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 3,060
Liabilities for unpaid losses and allocated LAE, net of reinsurance	232,934
2020 | Non-life Run-off | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	10,887
2020 | Non-life Run-off | Accident Year - 2010 and Prior
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	256,228
Incurred losses and allocated loss adjustment expenses, net of reinsurance	169,601
IBNR losses and loss expenses, net of reinsurance	$ 91,688
Cumulative Number of Claims | claim	47
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 2,310
2020 | Non-life Run-off | Accident Year - 2010 and Prior | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	43,511
Incurred losses and allocated loss adjustment expenses, net of reinsurance	43,849
IBNR losses and loss expenses, net of reinsurance	$ 36,455
Cumulative Number of Claims | claim	36
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 522
2020 | Non-life Run-off | Accident Year - 2010 and Prior | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2020 | Non-life Run-off | Accident Year - 2010 and Prior | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	4,680
Incurred losses and allocated loss adjustment expenses, net of reinsurance	4,678
IBNR losses and loss expenses, net of reinsurance	$ 4,679
Cumulative Number of Claims | claim	1
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2020 | Non-life Run-off | Accident Year - 2011
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	26,488
Incurred losses and allocated loss adjustment expenses, net of reinsurance	26,983
IBNR losses and loss expenses, net of reinsurance	$ 25,162
Cumulative Number of Claims | claim	36
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 54
2020 | Non-life Run-off | Accident Year - 2011 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	26,434
Incurred losses and allocated loss adjustment expenses, net of reinsurance	26,928
IBNR losses and loss expenses, net of reinsurance	$ 25,133
Cumulative Number of Claims | claim	29
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 54
2020 | Non-life Run-off | Accident Year - 2011 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2020 | Non-life Run-off | Accident Year - 2011 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	44
Incurred losses and allocated loss adjustment expenses, net of reinsurance	44
IBNR losses and loss expenses, net of reinsurance	$ 44
Cumulative Number of Claims | claim	3
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2020 | Non-life Run-off | Accident Year - 2012
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	58,128
Incurred losses and allocated loss adjustment expenses, net of reinsurance	58,241
IBNR losses and loss expenses, net of reinsurance	$ 53,749
Cumulative Number of Claims | claim	74
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 601
2020 | Non-life Run-off | Accident Year - 2012 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	55,478
Incurred losses and allocated loss adjustment expenses, net of reinsurance	55,591
IBNR losses and loss expenses, net of reinsurance	$ 51,130
Cumulative Number of Claims | claim	60
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 601
2020 | Non-life Run-off | Accident Year - 2012 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2020 | Non-life Run-off | Accident Year - 2012 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	2,593
Incurred losses and allocated loss adjustment expenses, net of reinsurance	2,593
IBNR losses and loss expenses, net of reinsurance	$ 2,584
Cumulative Number of Claims | claim	4
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2020 | Non-life Run-off | Accident Year - 2013
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	68,683
Incurred losses and allocated loss adjustment expenses, net of reinsurance	63,922
IBNR losses and loss expenses, net of reinsurance	$ 47,944
Cumulative Number of Claims | claim	140
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 4,283
2020 | Non-life Run-off | Accident Year - 2013 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	60,872
Incurred losses and allocated loss adjustment expenses, net of reinsurance	56,111
IBNR losses and loss expenses, net of reinsurance	$ 41,186
Cumulative Number of Claims | claim	122
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 3,258
2020 | Non-life Run-off | Accident Year - 2013 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2020 | Non-life Run-off | Accident Year - 2013 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	7,791
Incurred losses and allocated loss adjustment expenses, net of reinsurance	7,791
IBNR losses and loss expenses, net of reinsurance	$ 6,745
Cumulative Number of Claims | claim	6
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,025
2020 | Non-life Run-off | Accident Year - 2014
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	100,054
Incurred losses and allocated loss adjustment expenses, net of reinsurance	102,600
IBNR losses and loss expenses, net of reinsurance	$ 83,249
Cumulative Number of Claims | claim	201
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 5,975
2020 | Non-life Run-off | Accident Year - 2014 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	87,620
Incurred losses and allocated loss adjustment expenses, net of reinsurance	90,182
IBNR losses and loss expenses, net of reinsurance	$ 71,022
Cumulative Number of Claims | claim	185
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 5,983
2020 | Non-life Run-off | Accident Year - 2014 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2020 | Non-life Run-off | Accident Year - 2014 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	11,949
Incurred losses and allocated loss adjustment expenses, net of reinsurance	11,949
IBNR losses and loss expenses, net of reinsurance	$ 11,947
Cumulative Number of Claims | claim	4
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2020 | Non-life Run-off | Accident Year - 2015
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	161,383
Incurred losses and allocated loss adjustment expenses, net of reinsurance	161,352
IBNR losses and loss expenses, net of reinsurance	$ 113,476
Cumulative Number of Claims | claim	384
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 12,253
2020 | Non-life Run-off | Accident Year - 2015 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	140,583
Incurred losses and allocated loss adjustment expenses, net of reinsurance	139,947
IBNR losses and loss expenses, net of reinsurance	$ 96,032
Cumulative Number of Claims | claim	280
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 10,230
2020 | Non-life Run-off | Accident Year - 2015 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	2,397
Incurred losses and allocated loss adjustment expenses, net of reinsurance	3,018
IBNR losses and loss expenses, net of reinsurance	$ 603
Cumulative Number of Claims | claim	19
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 2,012
2020 | Non-life Run-off | Accident Year - 2015 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	16,120
Incurred losses and allocated loss adjustment expenses, net of reinsurance	16,120
IBNR losses and loss expenses, net of reinsurance	$ 15,769
Cumulative Number of Claims | claim	4
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 6
2020 | Non-life Run-off | Accident Year - 2016
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	210,661
Incurred losses and allocated loss adjustment expenses, net of reinsurance	205,305
IBNR losses and loss expenses, net of reinsurance	$ 120,481
Cumulative Number of Claims | claim	816
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 33,985
2020 | Non-life Run-off | Accident Year - 2016 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	142,395
Incurred losses and allocated loss adjustment expenses, net of reinsurance	143,156
IBNR losses and loss expenses, net of reinsurance	$ 100,293
Cumulative Number of Claims | claim	394
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 9,125
2020 | Non-life Run-off | Accident Year - 2016 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	48,505
Incurred losses and allocated loss adjustment expenses, net of reinsurance	42,420
IBNR losses and loss expenses, net of reinsurance	$ 2,779
Cumulative Number of Claims | claim	221
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 24,804
2020 | Non-life Run-off | Accident Year - 2016 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	16,259
Incurred losses and allocated loss adjustment expenses, net of reinsurance	16,216
IBNR losses and loss expenses, net of reinsurance	$ 16,053
Cumulative Number of Claims | claim	9
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1
2020 | Non-life Run-off | Accident Year - 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	316,751
Incurred losses and allocated loss adjustment expenses, net of reinsurance	342,330
IBNR losses and loss expenses, net of reinsurance	$ 168,832
Cumulative Number of Claims | claim	1,770
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 73,001
2020 | Non-life Run-off | Accident Year - 2017 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	142,862
Incurred losses and allocated loss adjustment expenses, net of reinsurance	137,097
IBNR losses and loss expenses, net of reinsurance	$ 112,135
Cumulative Number of Claims | claim	439
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 4,149
2020 | Non-life Run-off | Accident Year - 2017 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	154,070
Incurred losses and allocated loss adjustment expenses, net of reinsurance	185,445
IBNR losses and loss expenses, net of reinsurance	$ 38,279
Cumulative Number of Claims | claim	1,099
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 68,712
2020 | Non-life Run-off | Accident Year - 2017 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	17,212
Incurred losses and allocated loss adjustment expenses, net of reinsurance	17,206
IBNR losses and loss expenses, net of reinsurance	$ 16,906
Cumulative Number of Claims | claim	41
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 5
2020 | Non-life Run-off | Accident Year - 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	432,590
Incurred losses and allocated loss adjustment expenses, net of reinsurance	575,706
IBNR losses and loss expenses, net of reinsurance	$ 305,471
Cumulative Number of Claims | claim	3,108
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 111,871
2020 | Non-life Run-off | Accident Year - 2018 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	141,803
Incurred losses and allocated loss adjustment expenses, net of reinsurance	138,267
IBNR losses and loss expenses, net of reinsurance	$ 133,942
Cumulative Number of Claims | claim	316
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 400
2020 | Non-life Run-off | Accident Year - 2018 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	250,028
Incurred losses and allocated loss adjustment expenses, net of reinsurance	397,413
IBNR losses and loss expenses, net of reinsurance	$ 145,623
Cumulative Number of Claims | claim	2,204
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 110,447
2020 | Non-life Run-off | Accident Year - 2018 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	25,323
Incurred losses and allocated loss adjustment expenses, net of reinsurance	25,290
IBNR losses and loss expenses, net of reinsurance	$ 19,209
Cumulative Number of Claims | claim	115
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 475
2020 | Non-life Run-off | Accident Year - 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	344,495
Incurred losses and allocated loss adjustment expenses, net of reinsurance	343,168
IBNR losses and loss expenses, net of reinsurance	$ 301,463
Cumulative Number of Claims | claim	1,351
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,509
2020 | Non-life Run-off | Accident Year - 2019 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	202,521
Incurred losses and allocated loss adjustment expenses, net of reinsurance	201,174
IBNR losses and loss expenses, net of reinsurance	$ 179,284
Cumulative Number of Claims | claim	388
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 203
2020 | Non-life Run-off | Accident Year - 2019 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2020 | Non-life Run-off | Accident Year - 2019 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	99,460
Incurred losses and allocated loss adjustment expenses, net of reinsurance	99,350
IBNR losses and loss expenses, net of reinsurance	$ 92,944
Cumulative Number of Claims | claim	135
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 410
2020 | Non-life Run-off | Accident Year - 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	166,946
Incurred losses and allocated loss adjustment expenses, net of reinsurance	168,091
IBNR losses and loss expenses, net of reinsurance	$ 144,090
Cumulative Number of Claims | claim	1,481
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 7,695
2020 | Non-life Run-off | Accident Year - 2020 | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	83,021
Incurred losses and allocated loss adjustment expenses, net of reinsurance	82,598
IBNR losses and loss expenses, net of reinsurance	$ 77,737
Cumulative Number of Claims | claim	338
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 2,467
2020 | Non-life Run-off | Accident Year - 2020 | Motor
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	0
Incurred losses and allocated loss adjustment expenses, net of reinsurance	0
IBNR losses and loss expenses, net of reinsurance	$ 0
Cumulative Number of Claims | claim	0
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 0
2020 | Non-life Run-off | Accident Year - 2020 | Professional indemnity/ Directors & Officers
Liability for Claims and Claims Adjustment Expense [Line Items]
Total Net Reserves Acquired	34,548
Incurred losses and allocated loss adjustment expenses, net of reinsurance	34,757
IBNR losses and loss expenses, net of reinsurance	$ 30,144
Cumulative Number of Claims | claim	79
Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance	$ 1,138

Losses and Loss Adjustment E_12

Losses and Loss Adjustment Expenses - Average Annual Duration of Claims (Details)	Dec. 31, 2020
StarStone | Workers' compensation/personal accident
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	14.40%
Year 2	29.38%
Year 3	20.46%
Year 4	11.77%
Year 5	5.19%
Year 6	2.57%
Year 7	1.61%
Year 8	0.00%
Year 9	0.00%
Year 10	0.00%
StarStone | General Casualty
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	7.72%
Year 2	20.87%
Year 3	17.53%
Year 4	15.99%
Year 5	9.96%
Year 6	4.35%
Year 7	7.85%
Year 8	9.00%
Year 9	0.06%
Year 10	0.08%
StarStone | Marine
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	18.17%
Year 2	30.97%
Year 3	19.08%
Year 4	9.99%
Year 5	5.02%
Year 6	2.46%
Year 7	3.48%
Year 8	2.04%
Year 9	0.99%
Year 10	0.39%
StarStone | Property
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	19.10%
Year 2	28.75%
Year 3	26.40%
Year 4	8.35%
Year 5	2.47%
Year 6	2.69%
Year 7	1.55%
Year 8	1.01%
Year 9	0.02%
Year 10	0.30%
StarStone | Aerospace
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	32.80%
Year 2	29.84%
Year 3	15.40%
Year 4	4.61%
Year 5	4.31%
Year 6	2.22%
Year 7	1.93%
Year 8	1.12%
Year 9	0.48%
Year 10	0.01%
2011 | Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	25.68%
Year 2	17.45%
Year 3	(3.59%)
Year 4	(28.95%)
Year 5	(2.12%)
Year 6	3.57%
Year 7	(3.49%)
Year 8	4.99%
Year 9	11.18%
Year 10	8.86%
2012 | Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	1.30%
Year 2	26.42%
Year 3	16.71%
Year 4	12.48%
Year 5	10.00%
Year 6	4.47%
Year 7	5.48%
Year 8	4.17%
Year 9	2.12%
2013 | Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	25.96%
Year 2	21.67%
Year 3	15.93%
Year 4	11.01%
Year 5	6.15%
Year 6	3.89%
Year 7	2.24%
Year 8	0.32%
2014 | Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	33.84%
Year 2	24.15%
Year 3	11.11%
Year 4	8.07%
Year 5	3.74%
Year 6	1.65%
Year 7	1.10%
2015 | Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	17.33%
Year 2	17.09%
Year 3	12.84%
Year 4	9.80%
Year 5	7.69%
Year 6	4.65%
2015 | Non-life Run-off | Workers' compensation/personal accident
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	13.72%
Year 2	17.09%
Year 3	12.73%
Year 4	9.73%
Year 5	6.71%
Year 6	4.27%
2016 | Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	7.67%
Year 2	9.18%
Year 3	7.99%
Year 4	8.41%
Year 5	6.86%
2016 | Non-life Run-off | Workers' compensation/personal accident
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	10.33%
Year 2	8.96%
Year 3	7.09%
Year 4	9.89%
Year 5	8.22%
2017 | Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	8.04%
Year 2	7.64%
Year 3	6.71%
Year 4	6.11%
2018 | Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	12.86%
Year 2	25.40%
Year 3	12.00%
2018 | Non-life Run-off | Workers' compensation/personal accident
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	2.03%
Year 2	19.49%
Year 3	10.03%
2018 | Non-life Run-off | General Casualty
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	11.31%
Year 2	21.69%
Year 3	17.77%
2018 | Non-life Run-off | Professional indemnity/ Directors & Officers
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	19.55%
Year 2	14.40%
Year 3	5.34%
2018 | Non-life Run-off | Motor
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	11.08%
Year 2	38.47%
Year 3	17.61%
2019 | Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	11.11%
Year 2	12.68%
2019 | Non-life Run-off | Workers' compensation/personal accident
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	3.67%
Year 2	2.02%
2019 | Non-life Run-off | General Casualty
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	8.82%
Year 2	7.43%
2020 | Non-life Run-off
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	11.43%
2020 | Non-life Run-off | General Casualty
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	3.32%
2020 | Non-life Run-off | Professional indemnity/ Directors & Officers
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	1.30%
2020 | Non-life Run-off | Motor
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year 1	32.78%

Losses and Loss Adjustment E_13

Losses and Loss Adjustment Expenses - Reconciliation of Incurred and Paid Loss Development (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Atrium
Liability for Claims and Claims Adjustment Expense [Line Items]
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments		$ 225,684
StarStone
Liability for Claims and Claims Adjustment Expense [Line Items]
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$ 1,293,183	1,299,964
StarStone | General Casualty
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	331,154
Reinsurance recoverable on unpaid losses	61,082
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	392,236	332,914
StarStone | Marine
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	252,110
Reinsurance recoverable on unpaid losses	64,536
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	316,646	350,734
StarStone | Property
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	222,548
Reinsurance recoverable on unpaid losses	217,427
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	439,975	473,273
StarStone | Aerospace
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	60,340
Reinsurance recoverable on unpaid losses	60,353
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	120,693	108,089
StarStone | Workers' compensation/personal accident
Liability for Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated LAE, net of reinsurance	23,633
Reinsurance recoverable on unpaid losses	0
Gross liability for unpaid losses and LAE before unallocated loss adjustment expenses and fair value adjustments	$ 23,633	$ 34,954

Defendant Asbestos and Enviro_3

Defendant Asbestos and Environmental Liabilities - Liability for Asbestos and Liability Claims (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Estimated future expenses	$ 42,510	$ 51,637
Fair value adjustments	(262,029)	(314,824)
Defendant asbestos and environmental liabilities	706,329	847,685	$ 203,320	$ 219,164
Insurance recoveries related to defendant asbestos liabilities (net of allowance: 2020 - $4,824)	310,602	549,593
Fair value adjustments	(60,950)	(100,738)
Insurance balances recoverable	249,652	448,855	135,808	$ 122,326
Net liabilities relating to defendant asbestos and environmental exposures	456,677	398,830	67,512
Insurance balance recoverable, allowance for credit loss	4,824	3,818	$ 0
Defendant asbestos liabilities
Loss Contingencies [Line Items]
Defendant asbestos and environmental liabilities	913,276	1,100,593
Defendant environmental liabilities
Loss Contingencies [Line Items]
Defendant asbestos and environmental liabilities	$ 12,572	$ 10,279

Defendant Asbestos and Enviro_4

Defendant Asbestos and Environmental Liabilities - Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Balance as of January 1	$ 847,685	$ 203,320	$ 219,164
Less: Insurance balances recoverable	448,855	135,808	122,326
Plus: Cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible insurance balances	4,824	3,818	0
Net balance as of January 1	398,830	67,512
Total net recoveries (paid claims)	153,964	(10,434)	(6,351)
Amounts recorded in other income (expense):
Change in estimate of net ultimate liabilities	(103,166)	(4,263)	(23,221)
Reduction in estimated future expenses	(9,126)	(3,274)	0
Amortization of fair value adjustments	13,008	13,500	246
Total other expense (income)	(99,284)	5,963	(22,975)
Acquired on purchase of subsidiaries	0	335,789	0
Net balance as of December 31	456,677	398,830	67,512
Plus: insurance balances recoverable	249,652	448,855	135,808
Balance as of December 31	706,329	847,685	203,320
Cumulative effect of change in accounting principle
Liability for Claims and Claims Adjustment Expense [Line Items]
Plus: Cumulative effect of change in accounting principle on the determination of the allowance for estimated uncollectible insurance balances		3,167	0	$ 0
Cumulative effect of change in accounting principle, adjusted balance
Liability for Claims and Claims Adjustment Expense [Line Items]
Net balance as of January 1	$ 401,997	67,512	96,838
Amounts recorded in other income (expense):
Net balance as of December 31		$ 401,997	$ 67,512

Defendant Asbestos and Enviro_5

Defendant Asbestos and Environmental Liabilities - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)site	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
Other expense (income)	$ (99,284)	$ 5,963	$ (22,975)
Collection of disputed insurance recoveries	166,700
Proceeds from disputed insurance recoveries	179,600
Recovery of previously written-off insurance payments	19,300
Asbestos and environmental liabilities	$ 2,100,000	2,300,000
Number of hazardous waste disposal sites | site	22
Defendant asbestos liabilities
Liability for Claims and Claims Adjustment Expense [Line Items]
Asbestos and environmental liabilities	$ 913,300	1,100,000
Defendant environmental liabilities
Liability for Claims and Claims Adjustment Expense [Line Items]
Asbestos and environmental liabilities	$ 12,600	$ 10,300

Defendant Asbestos and Enviro_6

Defendant Asbestos and Environmental Liabilities - Allowance for Credit Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Liability For Asbestos And Environmental Claims, Allowance for Credit Loss [Roll Forward]
Allowance for estimated uncollectible insurance balances, beginning of year	$ 3,818	$ 0
Current period change in the allowance	(2,161)	3,818
Allowance for estimated uncollectible insurance balances, end of year	4,824	3,818
Cumulative effect of change in accounting principle
Liability For Asbestos And Environmental Claims, Allowance for Credit Loss [Roll Forward]
Allowance for estimated uncollectible insurance balances, beginning of year	$ 3,167	0
Allowance for estimated uncollectible insurance balances, end of year		$ 3,167

Fair Value Measurements - Categ

Fair Value Measurements - Categorized Investments and Assets Carried at Cost or Amortized Cost and Fair Value Among Levels (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	$ 846,795	$ 726,721
Total investments	9,319,179	9,034,557
Reinsurance balances recoverable on paid and unpaid losses	(21,427)	(88,086)
Other Assets:
Losses and LAE	2,452,920	2,621,122
U.S. government and agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	951,048	696,077
U.K. government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	51,082	161,772
Corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	5,686,732	5,448,270
Municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	162,669	140,687
Residential mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	553,945	400,914
Commercial mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	854,090	813,746
Asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	557,460	670,235
Publicly traded equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	260,767	327,875
Exchange-traded funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	311,287	133,047
Private equity funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	274,741	265,799
Private equity funds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	284,300
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	846,795	726,721
Total investments	14,424,635	12,293,516
Cash and cash equivalents	594,062	367,175
Other Assets:
Losses and LAE	2,452,920	2,621,122
Recurring | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	9,319,179	9,034,557
Recurring | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	4,244,034	2,518,031
Recurring | Reinsurance balances recoverable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	520,830	695,518
Recurring | Other Assets
Other Assets:
Derivative instruments	4,133	2,011
Recurring | Other Liabilities
Other Liabilities:
Derivative instruments	34,142	15,558
Recurring | Designated as Hedging Instrument | Other Assets
Other Assets:
Derivative instruments	1,169	642
Recurring | Designated as Hedging Instrument | Other Liabilities
Other Liabilities:
Derivative instruments	28,947	11,452
Recurring | Not Designated as Hedging Instrument | Other Assets
Other Assets:
Derivative instruments	2,964	1,369
Recurring | Not Designated as Hedging Instrument | Other Liabilities
Other Liabilities:
Derivative instruments	5,195	4,106
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	540,454	430,357
Total investments	540,454	430,357
Cash and cash equivalents	385,790	144,984
Other Assets:
Losses and LAE	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Reinsurance balances recoverable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Assets
Other Assets:
Derivative instruments	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Liabilities
Other Liabilities:
Derivative instruments	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Designated as Hedging Instrument | Other Assets
Other Assets:
Derivative instruments	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Designated as Hedging Instrument | Other Liabilities
Other Liabilities:
Derivative instruments	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Not Designated as Hedging Instrument | Other Assets
Other Assets:
Derivative instruments	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Not Designated as Hedging Instrument | Other Liabilities
Other Liabilities:
Derivative instruments	0	0
Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	31,600	30,565
Total investments	9,784,399	9,588,546
Cash and cash equivalents	208,272	222,191
Other Assets:
Losses and LAE	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	9,319,179	9,034,557
Recurring | Significant Other Observable Inputs (Level 2) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	418,993	509,217
Recurring | Significant Other Observable Inputs (Level 2) | Reinsurance balances recoverable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Other Assets
Other Assets:
Derivative instruments	4,133	2,011
Recurring | Significant Other Observable Inputs (Level 2) | Other Liabilities
Other Liabilities:
Derivative instruments	34,142	15,558
Recurring | Significant Other Observable Inputs (Level 2) | Designated as Hedging Instrument | Other Assets
Other Assets:
Derivative instruments	1,169	642
Recurring | Significant Other Observable Inputs (Level 2) | Designated as Hedging Instrument | Other Liabilities
Other Liabilities:
Derivative instruments	28,947	11,452
Recurring | Significant Other Observable Inputs (Level 2) | Not Designated as Hedging Instrument | Other Assets
Other Assets:
Derivative instruments	2,964	1,369
Recurring | Significant Other Observable Inputs (Level 2) | Not Designated as Hedging Instrument | Other Liabilities
Other Liabilities:
Derivative instruments	5,195	4,106
Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	274,741	265,799
Total investments	284,305	353,668
Cash and cash equivalents	0	0
Other Assets:
Losses and LAE	2,452,920	2,621,122
Recurring | Significant Unobservable Inputs (Level 3) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	9,564	87,869
Recurring | Significant Unobservable Inputs (Level 3) | Reinsurance balances recoverable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	520,830	695,518
Recurring | Significant Unobservable Inputs (Level 3) | Other Assets
Other Assets:
Derivative instruments	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Other Liabilities
Other Liabilities:
Derivative instruments	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Designated as Hedging Instrument | Other Assets
Other Assets:
Derivative instruments	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Designated as Hedging Instrument | Other Liabilities
Other Liabilities:
Derivative instruments	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Not Designated as Hedging Instrument | Other Assets
Other Assets:
Derivative instruments	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Not Designated as Hedging Instrument | Other Liabilities
Other Liabilities:
Derivative instruments	0	0
Recurring | Fair Value Based on NAV as Practical Expedient
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	3,815,477	1,920,945
Cash and cash equivalents	0	0
Recurring | Fair Value Based on NAV as Practical Expedient | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	3,815,477	1,920,945
Recurring | U.S. government and agency | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	951,048	696,077
Recurring | U.S. government and agency | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | U.S. government and agency | Significant Other Observable Inputs (Level 2) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	951,048	696,077
Recurring | U.S. government and agency | Significant Unobservable Inputs (Level 3) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | U.K. government | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	51,082	161,772
Recurring | U.K. government | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | U.K. government | Significant Other Observable Inputs (Level 2) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	51,082	161,772
Recurring | U.K. government | Significant Unobservable Inputs (Level 3) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Other government | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	502,153	702,856
Recurring | Other government | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Other government | Significant Other Observable Inputs (Level 2) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	502,153	702,856
Recurring | Other government | Significant Unobservable Inputs (Level 3) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Corporate | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	5,686,732	5,448,270
Recurring | Corporate | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Corporate | Significant Other Observable Inputs (Level 2) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	5,686,732	5,448,270
Recurring | Corporate | Significant Unobservable Inputs (Level 3) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Municipal | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	162,669	140,687
Recurring | Municipal | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Municipal | Significant Other Observable Inputs (Level 2) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	162,669	140,687
Recurring | Municipal | Significant Unobservable Inputs (Level 3) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Residential mortgage-backed | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	553,945	400,914
Recurring | Residential mortgage-backed | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Residential mortgage-backed | Significant Other Observable Inputs (Level 2) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	553,945	400,914
Recurring | Residential mortgage-backed | Significant Unobservable Inputs (Level 3) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Commercial mortgage-backed | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	854,090	813,746
Recurring | Commercial mortgage-backed | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Commercial mortgage-backed | Significant Other Observable Inputs (Level 2) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	854,090	813,746
Recurring | Commercial mortgage-backed | Significant Unobservable Inputs (Level 3) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Asset-backed | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	557,460	670,235
Recurring | Asset-backed | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Asset-backed | Significant Other Observable Inputs (Level 2) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	557,460	670,235
Recurring | Asset-backed | Significant Unobservable Inputs (Level 3) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Funds Held - Directly Managed | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	14,627	14,207
Recurring | Funds Held - Directly Managed | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Funds Held - Directly Managed | Significant Other Observable Inputs (Level 2) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	14,627	14,207
Recurring | Funds Held - Directly Managed | Significant Unobservable Inputs (Level 3) | Short-term investments and fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturity investments	0	0
Recurring | Publicly traded equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	260,767	327,875
Recurring | Publicly traded equity investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	229,167	297,310
Recurring | Publicly traded equity investments | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	31,600	30,565
Recurring | Publicly traded equity investments | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	0	0
Recurring | Exchange-traded funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	311,287	133,047
Recurring | Exchange-traded funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	311,287	133,047
Recurring | Exchange-traded funds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	0	0
Recurring | Exchange-traded funds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	0	0
Recurring | Private equity funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	274,741	265,799
Recurring | Private equity funds | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	363,103	323,496
Recurring | Private equity funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	0	0
Recurring | Private equity funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | Private equity funds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	0	0
Recurring | Private equity funds | Significant Other Observable Inputs (Level 2) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | Private equity funds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity investments	274,741	265,799
Recurring | Private equity funds | Significant Unobservable Inputs (Level 3) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | Private equity funds | Fair Value Based on NAV as Practical Expedient | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	363,103	323,496
Recurring | Hedge funds | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	2,638,339	1,121,904
Recurring | Hedge funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | Hedge funds | Significant Other Observable Inputs (Level 2) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | Hedge funds | Significant Unobservable Inputs (Level 3) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | Hedge funds | Fair Value Based on NAV as Practical Expedient | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	2,638,339	1,121,904
Recurring | Fixed income funds | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	552,541	481,039
Recurring | Fixed income funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | Fixed income funds | Significant Other Observable Inputs (Level 2) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	285,837	398,143
Recurring | Fixed income funds | Significant Unobservable Inputs (Level 3) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | Fixed income funds | Fair Value Based on NAV as Practical Expedient | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	266,704	82,896
Recurring | Equity funds | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	190,767	410,149
Recurring | Equity funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | Equity funds | Significant Other Observable Inputs (Level 2) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	5,073	111,040
Recurring | Equity funds | Significant Unobservable Inputs (Level 3) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | Equity funds | Fair Value Based on NAV as Practical Expedient | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	185,694	299,109
Recurring | CLO equities | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	128,083	87,555
Recurring | CLO equities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | CLO equities | Significant Other Observable Inputs (Level 2) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	128,083	0
Recurring | CLO equities | Significant Unobservable Inputs (Level 3) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	87,555
Recurring | CLO equities | Fair Value Based on NAV as Practical Expedient | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | CLO equity funds | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	166,523	87,509
Recurring | CLO equity funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | CLO equity funds | Significant Other Observable Inputs (Level 2) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | CLO equity funds | Significant Unobservable Inputs (Level 3) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | CLO equity funds | Fair Value Based on NAV as Practical Expedient | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	166,523	87,509
Recurring | Private credit funds | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	192,319
Recurring | Private credit funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0
Recurring | Private credit funds | Significant Other Observable Inputs (Level 2) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0
Recurring | Private credit funds | Significant Unobservable Inputs (Level 3) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	9,250
Recurring | Private credit funds | Fair Value Based on NAV as Practical Expedient | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	183,069
Recurring | Other | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	12,359	6,379
Recurring | Other | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	0
Recurring | Other | Significant Other Observable Inputs (Level 2) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	0	34
Recurring | Other | Significant Unobservable Inputs (Level 3) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	314	314
Recurring | Other | Fair Value Based on NAV as Practical Expedient | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	$ 12,045	$ 6,031

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation for Investments Measured At Fair Value on Recurring Basis Level 3 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	$ 353,668	$ 321,973
Purchases	67,217	87,805
Sales	(1,289)	(10,515)
Total realized and unrealized losses	(51,551)	984
Transfer into Level 3 from Level 2		26,176
Transfer out of Level 3 into Level 2	(83,740)	(72,755)
Ending fair value	284,305	353,668
Corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	0	37,386
Purchases		184
Sales		(3,520)
Total realized and unrealized losses		90
Transfer into Level 3 from Level 2		3,535
Transfer out of Level 3 into Level 2		(37,675)
Ending fair value		0
Residential mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	0	0
Purchases		0
Sales		0
Total realized and unrealized losses		(1)
Transfer into Level 3 from Level 2		102
Transfer out of Level 3 into Level 2		(101)
Ending fair value		0
Commercial mortgage-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	0	7,389
Purchases		0
Sales		(784)
Total realized and unrealized losses		64
Transfer into Level 3 from Level 2		1,515
Transfer out of Level 3 into Level 2		(8,184)
Ending fair value		0
Asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	0	9,121
Purchases		0
Sales		(3,605)
Total realized and unrealized losses		255
Transfer into Level 3 from Level 2		21,024
Transfer out of Level 3 into Level 2		(26,795)
Ending fair value		0
Privately-held Equities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	265,799	228,710
Purchases	20,125	30,713
Sales	0	(2,016)
Total realized and unrealized losses	(11,183)	8,392
Transfer into Level 3 from Level 2		0
Transfer out of Level 3 into Level 2	0	0
Ending fair value	274,741	265,799
Other Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning fair value	87,869	39,367
Purchases	47,092	56,908
Sales	(1,289)	(590)
Total realized and unrealized losses	(40,368)	(7,816)
Transfer into Level 3 from Level 2		0
Transfer out of Level 3 into Level 2	(83,740)	0
Ending fair value	$ 9,564	$ 87,869

Fair Value Measurements - Valua

Fair Value Measurements - Valuation Techniques and Inputs (Details) - Private equity funds - Significant Unobservable Inputs (Level 3) $ in Millions	Dec. 31, 2020USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 284.3
Guideline company methodology
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	230.3
Cost as approximation of fair value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value	$ 54
Arithmetic Average | Guideline company methodology | Distribution waterfall
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Alternative investments, measurement input	12.98

Fair Value Measurements - Insur

Fair Value Measurements - Insurance Contracts - Fair Value Option (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reinsurance balances recoverable on paid and unpaid losses
Beginning fair value	$ 353,668	$ 321,973
Assumed business	67,217	87,805
Incurred losses and LAE:
Change in fair value	(51,551)	984
Ending fair value	284,305	353,668	$ 321,973
Net
Beginning fair value	1,925,604	2,134,464
Assumed business	182,498	9,218
Incurred losses and LAE:
Reduction in estimates of ultimate losses	(133,074)	(29,732)
Reduction in unallocated LAE	(17,484)	(19,915)
Change in fair value	119,046	117,181	6,664
Total incurred losses and LAE	(31,512)	67,534
Paid losses	(198,908)	(324,625)
Effect of exchange rate movements	54,408	39,013
Ending fair value	1,932,090	1,925,604	2,134,464
Components of Changes in Fair Value
Change in fair value	119,046	117,181	6,664
Reinsurance balances recoverable on paid and unpaid losses
Reinsurance balances recoverable on paid and unpaid losses
Beginning fair value	695,518	739,591
Assumed business	(180,972)	0
Incurred losses and LAE:
Reduction in estimates of ultimate losses	59,478	(2,958)
Reduction in unallocated LAE	0	0
Change in fair value	38,919	43,449
Total incurred losses and LAE	98,397	40,491
Paid losses	(101,326)	(92,145)
Effect of exchange rate movements	9,213	7,581
Ending fair value	520,830	695,518	739,591
Liability for losses and LAE
Liability for losses and LAE
Beginning fair value	2,621,122	2,874,055
Assumed business	1,526	9,218
Incurred losses and LAE:
Reduction in estimates of ultimate losses	(73,596)	(32,690)
Reduction in unallocated LAE	(17,484)	(19,915)
Change in fair value	157,965	160,630
Total incurred losses and LAE	66,885	108,025
Paid losses	(300,234)	(416,770)
Effect of exchange rate movements	63,621	46,594
Ending fair value	2,452,920	2,621,122	2,874,055
Duration
Incurred losses and LAE:
Change in fair value	20,861	22,719	74,011
Components of Changes in Fair Value
Change in fair value	20,861	22,719	74,011
Corporate bond yield
Incurred losses and LAE:
Change in fair value	96,478	94,462	(71,031)
Components of Changes in Fair Value
Change in fair value	96,478	94,462	(71,031)
Weighted cost of capital
Incurred losses and LAE:
Change in fair value	(5,048)	0
Components of Changes in Fair Value
Change in fair value	(5,048)	0
Risk cost of capital
Incurred losses and LAE:
Change in fair value	6,755	0	3,684
Components of Changes in Fair Value
Change in fair value	$ 6,755	$ 0	$ 3,684

Fair Value Measurements - Quant

Fair Value Measurements - Quantitative Information (Details) - Internal Model - Recurring	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Liability for losses and LAE
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Weighted average cost of capital	8.25%	8.50%
Fair value inputs, duration	8 years 2 months 1 day	7 years 9 months 25 days
Reinsurance balances recoverable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk cost of capital	5.10%	5.10%
Fair value inputs, duration	8 years 2 months 23 days	8 years 8 months 4 days
Credit spread for non-performing risk | Liability for losses and LAE
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Credit spread for non-performing risk	0.20%	0.20%

Fair Value Measurements - Fair

Fair Value Measurements - Fair Values for Financial Instruments Carried At Cost (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Aug. 26, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of debt	$ 1,373,259		$ 1,191,207
Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of debt	$ 843,447		842,216
Senior Notes | 4.50% Senior Notes due 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate	4.50%
Carrying value of debt	$ 349,253		348,616
Fair value of debt	$ 362,400
Senior Notes | 4.95% Senior Notes due 2029
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate	4.95%
Carrying value of debt	$ 494,194		493,600
Fair value of debt	$ 573,300
Junior Subordinated Notes | 5.75% Junior Subordinated Notes due 2040
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate	5.75%	5.75%
Carrying value of debt	$ 344,812		$ 0
Fair value of debt	$ 365,700

Premiums Written and Earned - S

Premiums Written and Earned - Schedule of Net Premiums Written and Earned (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effects of Reinsurance [Line Items]
Gross, premiums written									$ 551,983	$ 658,653	$ 817,532
Ceded, premiums written									(119,159)	(113,600)	(163,185)
Net, premiums written									432,824	545,053	654,347
Gross, premiums earned									729,918	949,530	862,113
Ceded, premiums earned									(157,826)	(145,483)	(166,334)
Net, premiums earned	$ 108,146	$ 161,724	$ 142,871	$ 159,351	$ 185,336	$ 175,802	$ 190,962	$ 251,947	572,092	804,047	695,779
Operating Segments | Non-life Run-off
Effects of Reinsurance [Line Items]
Gross, premiums written									5,191	(25,069)	(8,910)
Ceded, premiums written									(2,204)	(269)	(307)
Net, premiums written									2,987	(25,338)	(9,217)
Gross, premiums earned									71,522	197,009	25,230
Ceded, premiums earned									(12,827)	(28,513)	(15,803)
Net, premiums earned									58,695	168,496	9,427
Operating Segments | Atrium
Effects of Reinsurance [Line Items]
Gross, premiums written									206,656	192,373	171,494
Ceded, premiums written									(23,462)	(20,017)	(18,006)
Net, premiums written									183,194	172,356	153,488
Gross, premiums earned									197,492	182,678	164,428
Ceded, premiums earned									(22,099)	(18,619)	(18,113)
Net, premiums earned									175,393	164,059	146,315
Operating Segments | StarStone
Effects of Reinsurance [Line Items]
Gross, premiums written									326,695	472,815	622,570
Ceded, premiums written									(93,493)	(93,292)	(144,561)
Net, premiums written									233,202	379,523	478,009
Gross, premiums earned									441,015	549,299	647,218
Ceded, premiums earned									(122,900)	(98,187)	(132,055)
Net, premiums earned									318,115	451,112	515,163
Other
Effects of Reinsurance [Line Items]
Gross, premiums written									13,441	18,534	32,378
Ceded, premiums written									0	(22)	(311)
Net, premiums written									13,441	18,512	32,067
Gross, premiums earned									19,889	20,544	25,237
Ceded, premiums earned									0	(164)	(363)
Net, premiums earned									$ 19,889	$ 20,380	$ 24,874

Premiums Written and Earned - A

Premiums Written and Earned - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Insurance [Abstract]
Decrease in premiums written, gross	$ 106.7	$ 158.9

Goodwill and Intangible Assets-

Goodwill and Intangible Assets- Schedule of Goodwill, Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill
Goodwill, Beginning balance	$ 109,807	$ 109,807
Impairment losses (StarStone International)	(8,000)
Reclassification to assets held-for-sale (Atrium)	(38,848)
Goodwill, Ending balance	62,959	109,807	$ 109,807
Intangible assets with a definite life
Intangible assets with a definite life, Beginning balance	14,630	16,887
Amortization	(1,524)	(2,257)	(3,600)
Impairment losses (StarStone International)	0
Reclassification to assets held-for-sale (Atrium)	(13,106)
Intangible assets with a definite life, Ending balance	0	14,630	16,887
Intangible assets with an indefinite life
Intangible assets with an indefinite life, Beginning balance	67,131	67,131
Impairment losses (StarStone International)	(4,000)
Reclassification to assets held-for-sale (Atrium)	(63,131)
Intangible assets with an indefinite life, Ending balance	0	67,131	67,131
Goodwill and Intangible Assets [Roll Forward]
Goodwill and intangible assets, Beginning Balance	191,568	193,825
Impairment losses (StarStone International)	12,000
Reclassification to assets held-for-sale (Atrium)	115,085
Goodwill and intangible assets, Ending balance	62,959	191,568	$ 193,825
StarStone
Goodwill
Goodwill, Beginning balance	8,000
Impairment losses (StarStone International)	(8,000)
Goodwill, Ending balance	0	8,000
Goodwill and Intangible Assets [Roll Forward]
Goodwill and intangible assets, Beginning Balance	12,000
Goodwill and intangible assets, Ending balance	0	12,000
Lloyd’s syndicate capacity | StarStone
Intangible assets with an indefinite life
Intangible assets with an indefinite life, Beginning balance	4,000
Impairment losses (StarStone International)	(4,000)
Intangible assets with an indefinite life, Ending balance	$ 0	$ 4,000

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Summary of Gross Carrying Value, Accumulated Amortization and Net Carrying Value of Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill
Net carrying value	$ 62,959	$ 109,807	$ 109,807
Intangible assets with a definite life:
Accumulated amortization	0	(12,370)
Net carrying value	0	14,630	16,887
Intangible assets with an indefinite life:
Net carrying value	0	67,131	67,131
Gross carrying value	62,959	203,938
Net carrying value	62,959	191,568	$ 193,825
Non-life Run-off
Goodwill
Goodwill	62,959	62,959
Net carrying value	62,959	62,959
Atrium
Goodwill
Goodwill	0	38,848
Net carrying value	0	38,848
Intangible assets with a definite life:
Accumulated amortization	0	(12,370)
Intangible assets with an indefinite life:
Gross carrying value	0	128,979
Net carrying value	0	116,609
Atrium | Distribution channel
Intangible assets with a definite life:
Gross carrying value	0	20,000
Accumulated amortization	0	(8,111)
Net carrying value	0	11,889
Atrium | Brand
Intangible assets with a definite life:
Gross carrying value	0	7,000
Accumulated amortization	0	(4,259)
Net carrying value	0	2,741
StarStone
Goodwill
Goodwill	0	8,000
Net carrying value	0	8,000
Intangible assets with an indefinite life:
Gross carrying value	0	12,000
Net carrying value	0	12,000
Lloyd’s syndicate capacity | Atrium
Intangible assets with an indefinite life:
Gross carrying value	0	33,031
Net carrying value	0	33,031
Lloyd’s syndicate capacity | StarStone
Intangible assets with an indefinite life:
Gross carrying value	0	4,000
Net carrying value	0	4,000
Management contract | Atrium
Intangible assets with an indefinite life:
Gross carrying value	0	30,100
Net carrying value	$ 0	$ 30,100

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Intangible Assets Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization	$ 1,524	$ 2,257	$ 3,600

Debt Obligations and Credit F_3

Debt Obligations and Credit Facilities - Amounts of Outstanding Debt and Accrued Interest (Details) - USD ($) $ in Thousands	Dec. 27, 2018	Aug. 16, 2018	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Carrying value of debt			$ 1,373,259				$ 1,191,207				$ 1,373,259	$ 1,191,207
Interest expense on debt obligations											57,974	51,245	$ 25,205
Amortization of debt issuance costs											1,331	953	537
Funds withheld balances and other											3	343	(46)
Total interest expense			16,872	$ 15,003	$ 14,018	$ 13,415	13,519	$ 14,950	$ 13,036	$ 11,036	59,308	52,541	$ 25,696
Senior Notes
Line of Credit Facility [Line Items]
Carrying value of debt			843,447				842,216				$ 843,447	842,216
Senior Notes | 4.50% Senior Notes due 2022
Line of Credit Facility [Line Items]
Term											5 years
Carrying value of debt			349,253				348,616				$ 349,253	348,616
Senior Notes | 4.95% Senior Notes due 2029
Line of Credit Facility [Line Items]
Term											10 years
Carrying value of debt			494,194				493,600				$ 494,194	493,600
Junior Subordinated Notes | 5.75% Junior Subordinated Notes due 2040
Line of Credit Facility [Line Items]
Term											20 years
Carrying value of debt			344,812				0				$ 344,812	0
Loan facilities | EGL Revolving Credit Facility
Line of Credit Facility [Line Items]
Term		5 years									5 years
Carrying value of debt							0					0
Loan facilities | 2018 EGL Term Loan Facility
Line of Credit Facility [Line Items]
Term	3 years										3 years
Carrying value of debt			$ 0				$ 348,991				$ 0	$ 348,991

Debt Obligations and Credit F_4

Debt Obligations and Credit Facilities - Senior Notes (Details) $ in Millions	May 28, 2019USD ($)	Mar. 10, 2017USD ($)	Dec. 31, 2020USD ($)debt_instrument
Debt Instrument [Line Items]
Number of debt instruments | debt_instrument			2
Senior Notes | 4.50% Senior Notes due 2022
Debt Instrument [Line Items]
Interest rate			4.50%
Redemption price, percentage of principal amount			100.00%
Debt issuance costs		$ 2.9
Unamortized costs of debt			$ (0.7)
Senior Notes | 4.95% Senior Notes due 2029
Debt Instrument [Line Items]
Interest rate			4.95%
Debt issuance costs	$ 6.8
Unamortized costs of debt			$ (5.8)

Debt Obligations and Credit F_5

Debt Obligations and Credit Facilities - Junior Subordinated Notes (Details) - 5.75% Junior Subordinated Notes due 2040 - Junior Subordinated Notes - USD ($)	12 Months Ended	180 Months Ended
	Dec. 31, 2020	Sep. 01, 2040	Aug. 26, 2020
Debt Instrument [Line Items]
Interest rate	5.75%		5.75%
Aggregate principal amount			$ 350,000,000
Redemption price, percentage of principal amount	100.00%
Unamortized costs	$ 5,200,000		$ 5,200,000
Scenario, Forecast | Treasury rate
Debt Instrument [Line Items]
Basis spread on interest rate		5.468%

Debt Obligations and Credit F_6

Debt Obligations and Credit Facilities - EGL Revolving Credit Facility (Details) - Loan facilities - EGL Revolving Credit Facility	Aug. 16, 2018USD ($)	Mar. 01, 2021USD ($)	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Facility term	5 years		5 years
Maximum borrowing capacity	$ 600,000,000		$ 600,000,000
Increase in borrowing capacity, limit	$ 400,000,000
Available unutilized capacity			$ 415,000,000
Covenant compliance, consolidated indebtedness to total capitalization (not greater than)	0.35
Covenant compliance, net income (loss) threshold	$ 2,300,000,000
Covenant compliance, net income threshold percent	50.00%
Covenant compliance, percentage of proceeds of common stock issuance	50.00%
Subsequent Event
Debt Instrument [Line Items]
Available unutilized capacity		$ 425,000,000
Additional borrowings		(20,000,000)
Repayment of revolving credit facility		$ 30,000,000

Debt Obligations and Credit F_7

Debt Obligations and Credit Facilities - EGL Term Loan Facilities (Details) - USD ($)	Dec. 27, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Repayment of loans		$ 679,000,000	$ 742,574,000	$ 914,319,000
Loan facilities | 2018 EGL Term Loan Facility
Debt Instrument [Line Items]
Facility term	3 years	3 years
Maximum borrowing capacity	$ 500,000,000
Repayment of loans		$ 350,000,000	$ 150,000,000

Debt Obligations and Credit F_8

Debt Obligations and Credit Facilities - Maturities (Details)	Dec. 31, 2020USD ($)
Receivables [Abstract]
2021	$ 0
2022	350,000,000
2023	185,000,000
2024	0
Thereafter	$ 850,000,000

Debt Obligations and Credit F_9

Debt Obligations and Credit Facilities - Letters of Credit (Details)	Nov. 05, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 08, 2020USD ($)	Dec. 08, 2020GBP (£)	Aug. 04, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 06, 2019USD ($)	Dec. 22, 2017USD ($)
Debt Instrument [Line Items]
Cash and investments		$ 260,900,000				$ 639,300,000
Letters of Credit | Cavello Letter of Credit Facility | Loan facilities
Debt Instrument [Line Items]
Maximum borrowing capacity								$ 100,000,000
Letters of credit		100,000,000
Letters of Credit | Mercantile Letter of Credit Facility | Loan facilities
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 43,700,000	£ 32,000,000
Letters of credit		43,700,000
Letters of Credit | Loan facilities | FAL Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 275,000,000
Increase in borrowing capacity, limit	$ 75,000,000
Term extension	2 years
Available unutilized capacity		210,000,000				252,000,000
Letters of Credit | Loan facilities | 2018 Facility Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity							$ 120,000,000
Increase in borrowing capacity, limit							$ 60,000,000
Letters of credit		115,700,000				115,300,000
Letters of Credit | Loan facilities | Maiden Facility Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 800,000,000
Increase in borrowing capacity, limit					40,000,000
Letters of credit		$ 424,100,000				$ 608,000,000
Letters of Credit | Loan facilities | 2020 Letter of Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity					65,000,000
Letters of credit					$ 61,000,000

Noncontrolling Interest - Redee

Noncontrolling Interest - Redeemable Noncontrolling Interest (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Balance at beginning of year	$ 438,791	$ 458,543
Capital contributions	0	13,127
Dividends paid	0	(11,556)
Net losses attributable to RNCI	(27,512)	(12,029)
Change in unrealized gains (losses) on AFS investments attributable to RNCI	1,517	(126)
Change in currency translation adjustments attributable to RNCI	(1,397)	10
Change in redemption value of RNCI	(46,224)	(9,178)
Cumulative effect of change in accounting principle attributable to RNCI	261	0
Balance at end of year	$ 365,436	$ 438,791
North Bay | Trident
Redeemable Noncontrolling Interest [Line Items]
Ownership interest held by noncontrolling owners	39.30%
North Bay | Dowling
Redeemable Noncontrolling Interest [Line Items]
Ownership interest held by noncontrolling owners	1.70%
Subsidiaries | North Bay | Trident
Redeemable Noncontrolling Interest [Line Items]
Ownership interest held by noncontrolling owners	39.30%	39.30%
Subsidiaries | North Bay | Dowling
Redeemable Noncontrolling Interest [Line Items]
Ownership interest held by noncontrolling owners	1.70%	1.70%

Noncontrolling Interest - Nonco

Noncontrolling Interest - Noncontrolling Interest (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Noncontrolling Interest [Abstract]
Noncontrolling interest	$ 13,609	$ 14,168

Shareholders' Equity - Voting O

Shareholders' Equity - Voting Ordinary Shares (Details)	Jan. 21, 2020shares	May 14, 2018shares	Dec. 31, 2020USD ($)vote$ / sharesshares	Dec. 31, 2020USD ($)vote$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)	Mar. 09, 2020USD ($)
Class of Stock [Line Items]
Authorized share capital (shares)			111,000,000	111,000,000	111,000,000
Ordinary shares, par value (dollars per share) | $ / shares			$ 1	$ 1	$ 1
Preference shares (shares)			45,000,000	45,000,000	45,000,000
Preferred shares, par value (dollars per share) | $ / shares			$ 1	$ 1	$ 1
Authorized repurchase amount | $							$ 150,000,000
Treasury shares repurchased (shares)			178,280
Treasury shares repurchased, average price (dollars per share) | $ / shares			$ 145.87
Price of repurchased stock | $			$ 26,000,000	$ 26,006,000	$ 0	$ 0
Remaining repurchase amount | $			$ 124,000,000	$ 124,000,000
Chief Executive Officer | Joint Share Ownership Plan
Class of Stock [Line Items]
Shares subscribed (shares)	565,630
Voting ordinary shares
Class of Stock [Line Items]
Ordinary shares, par value (dollars per share) | $ / shares			$ 1	$ 1	$ 1
Number of votes | vote			1	1
Non-voting ordinary shares
Class of Stock [Line Items]
Ordinary shares, par value (dollars per share) | $ / shares			$ 1	$ 1	$ 1
KaylaRe
Class of Stock [Line Items]
Number of Enstar ordinary shares issued (shares)		2,007,017
KaylaRe | Ordinary Shares
Class of Stock [Line Items]
Number of Enstar ordinary shares issued (shares)		1,501,778

Shareholders' Equity - Non-Voti

Shareholders' Equity - Non-Voting Shares (Details) - shares	May 14, 2018	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2017
Class of Stock [Line Items]
Ordinary shares, issued (shares)		22,085,232	21,511,505
Ordinary shares, outstanding (shares)		22,085,232	21,511,505
Series C non-voting convertible ordinary shares
Class of Stock [Line Items]
Conversion ratio, issued upon conversion (shares)				1
Aggregate voting power of Company's issued share capital (percent) (not to exceed)				0.01%
Ordinary shares, issued (shares)		2,599,672	2,599,672
Ordinary shares, outstanding (shares)		2,599,672	2,599,672
Common Class B
Class of Stock [Line Items]
Ordinary shares, issued (shares)		0
Ordinary shares, outstanding (shares)		0
Common Class D
Class of Stock [Line Items]
Ordinary shares, issued (shares)		0
Ordinary shares, outstanding (shares)		0
Common Class E
Class of Stock [Line Items]
Ordinary shares, issued (shares)		910,010	910,010
Ordinary shares, outstanding (shares)		910,010	910,010
KaylaRe
Class of Stock [Line Items]
Number of Enstar Ordinary shares issued (in shares)	2,007,017
Common Class E | KaylaRe
Class of Stock [Line Items]
Number of Enstar Ordinary shares issued (in shares)	505,239

Shareholders' Equity - Warrants

Shareholders' Equity - Warrants (Details) - Common Class C	Dec. 31, 2020$ / sharesshares
Class of Stock [Line Items]
Warrants outstanding (shares) | shares	175,901
Warrants, exercise price (dollars per share) | $ / shares	$ 115

Shareholders' Equity - Preferre

Shareholders' Equity - Preferred Shares (Details) $ / shares in Units, $ in Millions	Nov. 21, 2018USD ($)$ / sharesshares	Jun. 28, 2018USD ($)$ / sharesshares	Dec. 31, 2020$ / sharesshares	Dec. 31, 2019$ / sharesshares
Class of Stock [Line Items]
Preferred shares, par value (dollars per share)			$ 1	$ 1
Series C Preferred Shares
Class of Stock [Line Items]
Preferred shares, issued (shares) | shares			388,571	388,571
Preferred shares, liquidation preference (dollars per share)			$ 0.001
Series D Preferred Stock
Class of Stock [Line Items]
Preferred shares, issued (shares) | shares			16,000	16,000
Dividend rate			7.00%
Series E Preferred Shares
Class of Stock [Line Items]
Preferred shares, issued (shares) | shares			4,400	4,400
Dividend rate			7.00%
Public Stock Offering | Series D Preferred Stock
Class of Stock [Line Items]
Preferred shares, liquidation preference (dollars per share)		$ 25,000
Consideration received on sale of stock | $		$ 400
Number of shares issued (shares) | shares		16,000
Dividend rate		7.00%
Depositary shares equivalent (shares) | shares		16,000,000
Depositary share, interest in preferred share		0.001
Preferred shares, par value (dollars per share)		$ 1
Liquidation preference per depositary share (dollars per share)		$ 25
Public Stock Offering | Series E Preferred Shares
Class of Stock [Line Items]
Preferred shares, liquidation preference (dollars per share)	$ 25,000
Consideration received on sale of stock | $	$ 110
Number of shares issued (shares) | shares	4,400
Dividend rate	7.00%
Depositary shares equivalent (shares) | shares	4,400,000
Depositary share, interest in preferred share	0.001
Preferred shares, par value (dollars per share)	$ 1
Liquidation preference per depositary share (dollars per share)	$ 25

Shareholders' Equity - Dividend

Shareholders' Equity - Dividends on Preferred Shares (Details) - USD ($) $ in Thousands	Feb. 05, 2021	Nov. 21, 2018	Jun. 28, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Total dividends paid				$ 35,700	$ 35,914	$ 12,133
Series D Preferred Shares
Class of Stock [Line Items]
Dividend rate				7.00%
Total dividends paid				$ 28,000	28,000	$ 12,100
Series E Preferred Shares
Class of Stock [Line Items]
Dividend rate				7.00%
Total dividends paid				$ 7,700	$ 7,900
Public Stock Offering | Series D Preferred Shares
Class of Stock [Line Items]
Dividend rate			7.00%
Public Stock Offering | Series E Preferred Shares
Class of Stock [Line Items]
Dividend rate		7.00%
LIBOR | Public Stock Offering | Series D Preferred Shares
Class of Stock [Line Items]
Basis spread on variable rate			4.015%
Subsequent Event | Series D Preferred Shares
Class of Stock [Line Items]
Total dividends paid	$ 7,000
Subsequent Event | Series E Preferred Shares
Class of Stock [Line Items]
Total dividends paid	$ 1,900

Shareholders' Equity - Changes

Shareholders' Equity - Changes in AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of year	$ 4,856,351
Unrealized gains (losses) on fixed income available-for-sale investments arising during the year	104,924	$ 2,896	$ (2,284)
Reclassification adjustment for net realized (gains) losses included in net earnings	(18,033)	(3,894)	63
Change in currency translation adjustment	(2,103)	(2,428)	(202)
Decrease in defined benefit pension liability	1,152	42	2,156
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(509)	0	0
Reclassification to earnings on disposal of subsidiary	(11,822)
Total other comprehensive income (loss)	73,609	(3,384)	(267)
Balance, end of year	6,688,004	4,856,351
Unrealized gains (losses) on fixed income available-for-sale investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Unrealized gains (losses) on fixed income available-for-sale investments arising during the year	104,924	2,896	(2,284)
Reclassification adjustment for net realized (gains) losses included in net earnings	(18,033)	(3,894)	63
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(509)
Reclassification to earnings on disposal of subsidiary	(11,856)
Total other comprehensive income (loss)	74,526	(998)	(2,221)
Unrealized gains (losses) on available-for-sale investments, Noncontrolling interests
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive (income) loss attributable to RNCI	(1,518)	125	222
Unrealized gains (losses) on available-for-sale investments, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of year	(432)	441	2,440
Total other comprehensive income (loss)	73,008	(873)	(1,999)
Balance, end of year	72,576	(432)	441
Cumulative Currency Translation Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Change in currency translation adjustment	(2,103)	(2,428)	(202)
Reclassification to earnings on disposal of subsidiary	34
Total other comprehensive income (loss)	(2,069)	(2,428)	(202)
Cumulative current translation adjustment, Noncontrolling interests
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive (income) loss attributable to RNCI	1,397	(10)	17
Cumulative current translation adjustment, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of year	8,548	10,986	11,171
Total other comprehensive income (loss)	(672)	(2,438)	(185)
Balance, end of year	7,876	8,548	10,986
Defined benefit pension liability, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of year	(945)	(987)	(3,143)
Decrease in defined benefit pension liability	1,152	42	2,156
Balance, end of year	207	(945)	(987)
Defined Benefit Pension Liability
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Decrease in defined benefit pension liability	1,152	42	2,156
Reclassification to earnings on disposal of subsidiary	0
Total other comprehensive income (loss)	1,152	42	2,156
Defined benefit pension liability, Noncontrolling interests
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive (income) loss attributable to RNCI	0	0	0
Accumulated Other Comprehensive Income, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of year	7,171	10,440	10,468
Balance, end of year	80,659	7,171	10,440
Accumulated Other Comprehensive Income
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Total other comprehensive income (loss)	73,609	(3,384)	(267)
Accumulated Other Comprehensive Income, Noncontrolling interests
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive (income) loss attributable to RNCI	$ (121)	$ 115	$ 239

Shareholders' Equity - Tax Effe

Shareholders' Equity - Tax Effect (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax Amount	$ 79,174
Tax (Expense) Benefit	(5,565)
Reclassification adjustment for net realized (gains) losses included in net earnings	(18,033)	$ (3,894)	$ 63
Total other comprehensive income (loss)	73,609	(3,384)	(267)
Unrealized gains (losses) on fixed income available-for-sale investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before reclassifications and tax	115,610
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(499)
Reclassification adjustment for net realized (gains) losses included in net earnings	(19,766)
Reclassification to earnings on disposal of subsidiary	(15,008)
Before reclassifications, tax	(10,686)
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(10)
Reclassification adjustment for net realized (gains) losses included in net earnings	1,733
Reclassification to earnings on disposal of subsidiary	3,152
Before reclassifications, net of tax amount	104,924
Reclassification adjustment for change in allowance for credit losses recognized in net earnings	(509)
Reclassification adjustment for net realized (gains) losses included in net earnings	(18,033)	(3,894)	63
Reclassification to earnings on disposal of subsidiary	(11,856)
Total other comprehensive income (loss)	74,526	(998)	(2,221)
Cumulative Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before reclassifications and tax	(2,294)
Reclassification to earnings on disposal of subsidiary	34
Before reclassifications, tax	191
Reclassification to earnings on disposal of subsidiary	0
Before reclassifications, net of tax amount	(2,103)
Reclassification to earnings on disposal of subsidiary	34
Total other comprehensive income (loss)	(2,069)	(2,428)	(202)
Defined Benefit Pension Liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before reclassifications and tax	1,097
Before reclassifications, tax	55
Before reclassifications, net of tax amount	1,152
Total other comprehensive income (loss)	$ 1,152	$ 42	$ 2,156

Shareholders' Equity - Reclassi

Shareholders' Equity - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net realized and unrealized gains (losses)	$ 803,467	$ 500,005	$ 967,608	$ (629,061)	$ 153,477	$ 145,060	$ 260,669	$ 452,760	$ 1,642,019	$ 1,011,966	$ (407,532)
Net earnings from discontinued operations, net of income taxes	15,441	4,031	(1,152)	(2,069)	(4,666)	7,916	(3,943)	8,068	16,251	7,375	1,489
Income tax (expense)	1,468	(13,915)	(16,652)	5,272	12,893	(13,465)	(7,698)	(4,102)	(23,827)	(12,372)	3,689
NET EARNINGS (LOSS)	$ 834,655	$ 645,850	$ 787,486	$ (540,618)	$ 197,864	$ 126,559	$ 238,054	$ 365,742	1,727,373	928,219	(212,272)
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
NET EARNINGS (LOSS)									30,364	3,894	(63)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on fixed income available-for-sale investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net realized and unrealized gains (losses)									18,682	3,894	(63)
Net earnings from discontinued operations, net of income taxes									16,591	0	0
Total before tax									35,273	3,894	(63)
Income tax (expense)									(4,875)	0	0
NET EARNINGS (LOSS)									30,398	3,894	(63)
Reclassification out of Accumulated Other Comprehensive Income | Cumulative Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net earnings from discontinued operations, net of income taxes									$ (34)	$ 0	$ 0

Earnings Per Share - Comparison

Earnings Per Share - Comparison of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net earnings (loss) from continuing operations									$ 1,711,810	$ 897,825	$ (163,232)
Net earnings from discontinued operations									7,534	4,350	878
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$ 822,599	$ 615,013	$ 798,553	$ (516,821)	$ 193,839	$ 117,743	$ 231,842	$ 358,751	$ 1,719,344	$ 902,175	$ (162,354)
Denominator:
Weighted-average ordinary shares outstanding — basic (shares)									21,551,408	21,482,617	20,698,310
Effect of dilutive securities:
Share-based compensation plans (shares)									208,293	227,878	129,746
Warrants (shares)									58,593	64,571	76,120
Weighted-average ordinary shares outstanding - diluted (shares)									21,818,294	21,775,066	20,904,176
Basic:
Net earnings (loss) from continuing operations (dollars per share)	$ 37.91	$ 28.39	$ 37.06	$ (23.93)	$ 9.15	$ 5.26	$ 10.90	$ 16.49	$ 79.43	$ 41.80	$ (7.89)
Net earnings from discontinued operations (dollars per share)	0.33	0.11	(0.03)	(0.05)	(0.13)	0.22	(0.11)	0.22	0.35	0.20	0.05
Net earnings (loss) per ordinary share (dollars per share)	38.24	28.50	37.03	(23.98)	9.02	5.48	10.79	16.71	79.78	42	(7.84)
Diluted:
Net earnings (loss) from continuing operations (dollars per share)	37.47	28.13	36.68	(23.93)	9.02	5.21	10.81	16.35	78.45	41.23	(7.89)
Net earnings from discontinued operations (dollars per share)	0.32	0.11	(0.03)	(0.05)	(0.13)	0.21	(0.11)	0.22	0.35	0.20	0.05
Net earnings (loss) per ordinary share (dollars per share)	$ 37.79	$ 28.24	$ 36.65	$ (23.98)	$ 8.89	$ 5.42	$ 10.70	$ 16.57	$ 78.80	$ 41.43	$ (7.84)

Share-Based Compensation and _3

Share-Based Compensation and Pensions - Compensation Costs for Share-based Compensation Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	$ 27,745	$ 37,999	$ 10,670
Tax benefit	2,700	2,900	1,900
Restricted shares and restricted share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	8,286	6,564	7,641
Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	12,678	23,582	1,968
Cash-settled stock appreciation rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	215	2,575	(3,316)
Employee share purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	339	411	430
Joint share ownership plan expense | Employee share purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	4,296	0
Northshore/Atrium incentive plan | Time-based restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	971	3,652	2,792
StarStone incentive plan | Time-based restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation costs	(223)	223	0
Deferred compensation and ordinary share plan for non-employee directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred compensation and ordinary share plan for non-employee directors	$ 1,183	$ 992	$ 1,155

Share-Based Compensation and _4

Share-Based Compensation and Pensions - Restricted Shares and Restricted Share Units (Details) - Restricted shares and restricted share units - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Number of Shares
Nonvested — January 1 (shares)	64,572
Granted (shares)	70,012
Vested (shares)	(38,961)
Forfeited (shares)	(373)
Nonvested — December 31 (shares)	95,250
Weighted-Average Share Price
Nonvested - January 1 (dollars per share)	$ 180.49
Granted (dollars per share)	152.28
Vested (dollars per share)	174.93
Forfeited (dollars per share)	177.73
Nonvested - December 31 (dollars per share)	$ 161.60
Unrecognized compensation cost	$ 7.9
Unrecognized compensation cost, period of recognition	2 years 25 days

Share-Based Compensation and _5

Share-Based Compensation and Pensions - Performance Share Units (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended				24 Months Ended	48 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2020
Performance share units, FDBVPS
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)						261,725
Forfeited (shares)						(28,721)
Estimated Change in Multiplier (shares)						45,680
Vested (shares)						(151,838)
Unnvested Units (shares)	126,846				126,846	126,846	126,846
Number of Shares
Granted (shares)						261,725
Increase for above target vest (shares)						45,680
Vested (shares)						(151,838)
Forfeited (shares)						(28,721)
Nonvested — December 31 (shares)	126,846				126,846	126,846
Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
PSU's Granted at Target (shares)	98,099
Forfeited (shares)	(7,442)
Estimated Change in Multiplier (shares)	25,850
Vested (shares)	(153,469)
Unnvested Units (shares)	169,987	206,949			169,987	169,987	169,987
Performance Criteria: Average Annual Operating ROE
Unrecognized compensation cost							$ 14.4
Unrecognized compensation cost, period of recognition	1 year 10 months 24 days
Number of Shares
Nonvested — January 1 (shares)	206,949
Granted (shares)	98,099
Increase for above target vest (shares)	25,850
Vested (shares)	(153,469)
Forfeited (shares)	(7,442)
Nonvested — December 31 (shares)	169,987	206,949			169,987	169,987
Weighted-Average Share Price
Nonvested - January 1 (dollars per share)	$ 185.61
Granted (dollars per share)	167.94
Increase for above target vest (dollars per share)	179.71
Vested (dollars per share)	187.24
Forfeited (dollars per share)	146.76
Nonvested - December 31 (dollars per share)	$ 174.10	$ 185.61			$ 174.10	$ 174.10
Performance share units, Average Operating ROE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)					40,868
Forfeited (shares)					(3,907)
Estimated Change in Multiplier (shares)					7,811
Vested (shares)					(1,631)
Unnvested Units (shares)	43,141				43,141	43,141	43,141
Number of Shares
Granted (shares)					40,868
Increase for above target vest (shares)					7,811
Vested (shares)					(1,631)
Forfeited (shares)					(3,907)
Nonvested — December 31 (shares)	43,141				43,141	43,141
Performance Target One | Performance share units | Minimum
Performance Criteria: Average Annual Operating ROE
Share settlement percentage	100.00%
Performance Target One | Performance share units | Maximum
Performance Criteria: Average Annual Operating ROE
Share settlement percentage	150.00%
Performance Target Two | Performance share units | Minimum
Performance Criteria: Average Annual Operating ROE
Share settlement percentage	60.00%
Performance Target Two | Performance share units | Maximum
Performance Criteria: Average Annual Operating ROE
Share settlement percentage	100.00%
2017 Awards | Performance share units, FDBVPS | Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)				36,321
Forfeited (shares)				(12,267)
Estimated Change in Multiplier (shares)				9,527
Vested (shares)				(33,581)
Unnvested Units (shares)	0				0	0	0
Performance Criteria: Change in FDBVPS (3 year)
Threshold	20.00%
Target	30.00%
Maximum	40.00%
Performance Multiplier Levels Per Award Agreements
Threshold	50.00%
Target	100.00%
Maximum	150.00%
Performance Criteria: Average Annual Operating ROE
Performance multiplier	139.00%	139.00%	50.00%
Number of Shares
Granted (shares)				36,321
Increase for above target vest (shares)				9,527
Vested (shares)				(33,581)
Forfeited (shares)				(12,267)
Nonvested — December 31 (shares)	0				0	0
2017 Awards | Performance share units, FDBVPS | Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)				91,875
Forfeited (shares)				0
Estimated Change in Multiplier (shares)				18,100
Vested (shares)				(109,975)
Unnvested Units (shares)	0				0	0	0
Performance Criteria: Change in FDBVPS (3 year)
Threshold	30.30%
Target	35.65%
Maximum	41.00%
Performance Multiplier Levels Per Award Agreements
Threshold	50.00%
Target	100.00%
Maximum	150.00%
Performance Criteria: Average Annual Operating ROE
Performance multiplier	120.00%	120.00%	50.00%
Number of Shares
Granted (shares)				91,875
Increase for above target vest (shares)				18,100
Vested (shares)				(109,975)
Forfeited (shares)				0
Nonvested — December 31 (shares)	0				0	0
2018 Awards | Performance share units, FDBVPS
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)			39,682
Forfeited (shares)			(12,545)
Estimated Change in Multiplier (shares)			10,218
Vested (shares)			(6,700)
Unnvested Units (shares)	30,655				30,655	30,655	30,655
Performance Criteria: Change in FDBVPS (3 year)
Threshold	25.00%
Target	32.50%
Maximum	40.00%
Performance Multiplier Levels Per Award Agreements
Threshold	50.00%
Target	100.00%
Maximum	150.00%
Performance Criteria: Average Annual Operating ROE
Performance multiplier	150.00%	100.00%	50.00%
Number of Shares
Granted (shares)			39,682
Increase for above target vest (shares)			10,218
Vested (shares)			(6,700)
Forfeited (shares)			(12,545)
Nonvested — December 31 (shares)	30,655				30,655	30,655
2019 Awards | Performance share units, FDBVPS
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)		18,308
Forfeited (shares)		(1,758)
Estimated Change in Multiplier (shares)		7,835
Vested (shares)		(881)
Unnvested Units (shares)	23,504				23,504	23,504	23,504
Performance Criteria: Change in FDBVPS (3 year)
Threshold	20.00%
Target	30.00%
Maximum	40.00%
Performance Multiplier Levels Per Award Agreements
Threshold	60.00%
Target	100.00%
Maximum	150.00%
Number of Shares
Granted (shares)		18,308
Increase for above target vest (shares)		7,835
Vested (shares)		(881)
Forfeited (shares)		(1,758)
Nonvested — December 31 (shares)	23,504				23,504	23,504
2019 Awards | Performance share units, FDBVPS | Tranche One
Performance Criteria: Average Annual Operating ROE
Performance multiplier	150.00%	100.00%
2019 Awards | Performance share units, Average Operating ROE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)		18,308
Forfeited (shares)		(1,756)
Estimated Change in Multiplier (shares)		7,811
Vested (shares)		(930)
Unnvested Units (shares)	23,433				23,433	23,433	23,433
Performance Multiplier Levels Per Award Agreements
Threshold	60.00%
Target	100.00%
Maximum	150.00%
Performance Criteria: Average Annual Operating ROE
Threshold	9.60%
Target	12.00%
Maximum	14.40%
Number of Shares
Granted (shares)		18,308
Increase for above target vest (shares)		7,811
Vested (shares)		(930)
Forfeited (shares)		(1,756)
Nonvested — December 31 (shares)	23,433				23,433	23,433
2019 Awards | Performance share units, Average Operating ROE | Tranche Two
Performance Criteria: Average Annual Operating ROE
Performance multiplier	150.00%	100.00%
2020 Awards | Performance share units, FDBVPS | Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)	22,591
Forfeited (shares)	(2,151)
Estimated Change in Multiplier (shares)	0
Vested (shares)		(701)
Unnvested Units (shares)	19,739				19,739	19,739	19,739
Performance Criteria: Change in FDBVPS (3 year)
Threshold	25.00%
Target	32.50%
Maximum	40.00%
Performance Multiplier Levels Per Award Agreements
Threshold	60.00%
Target	100.00%
Maximum	150.00%
Performance Criteria: Average Annual Operating ROE
Performance multiplier	100.00%
Number of Shares
Granted (shares)	22,591
Increase for above target vest (shares)	0
Vested (shares)		(701)
Forfeited (shares)	(2,151)
Nonvested — December 31 (shares)	19,739				19,739	19,739
2020 Awards | Performance share units, FDBVPS | Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)	52,948
Forfeited (shares)	0
Estimated Change in Multiplier (shares)	0
Vested (shares)		0
Unnvested Units (shares)	52,948				52,948	52,948	52,948
Performance Criteria: Change in FDBVPS (3 year)
Threshold	33.10%
Target	36.80%
Target +	44.30%
Maximum	52.10%
Performance Multiplier Levels Per Award Agreements
Threshold	50.00%
Target	100.00%
Target +	150.00%
Maximum	200.00%
Number of Shares
Granted (shares)	52,948
Increase for above target vest (shares)	0
Vested (shares)		0
Forfeited (shares)	0
Nonvested — December 31 (shares)	52,948				52,948	52,948
2020 Awards | Performance share units, FDBVPS | Tranche Three
Performance Criteria: Average Annual Operating ROE
Performance multiplier	100.00%
2020 Awards | Performance share units, Average Operating ROE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU's Granted at Target (shares)	22,560
Forfeited (shares)	(2,151)
Estimated Change in Multiplier (shares)	0
Vested (shares)	(701)
Unnvested Units (shares)	19,708				19,708	19,708	19,708
Performance Multiplier Levels Per Award Agreements
Threshold	60.00%
Target	100.00%
Maximum	150.00%
Performance Criteria: Average Annual Operating ROE
Threshold	9.60%
Target	12.00%
Maximum	14.40%
Number of Shares
Granted (shares)	22,560
Increase for above target vest (shares)	0
Vested (shares)	(701)
Forfeited (shares)	(2,151)
Nonvested — December 31 (shares)	19,708				19,708	19,708
2020 Awards | Performance share units, Average Operating ROE | Tranche Two
Performance Criteria: Average Annual Operating ROE
Performance multiplier	100.00%

Share-Based Compensation and _6

Share-Based Compensation and Pensions - Cash-Settled Stock Appreciation Rights (Detail) - Cash-settled stock appreciation rights - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of SARs
Balance, beginning of year, Number of SARs (shares)	89,227
Exercised, Number of SARs (shares)	(12,793)
Balance, end of year, Number of SARs (shares)	76,434	89,227
Weighted-Average Exercise Price of SARs
Balance, beginning of year, Weighted Average Exercise Price of SARs (dollars per share)	$ 143.33
Exercised, Weighted Average Exercise Price of SARs (dollars per share)	136.94
Balance, end of year, Weighted Average Exercise Price of SARs (dollars per share)	$ 144.40	$ 143.33
Balance, end of year, Weighted Average Remaining Contractual Term (in years)	1 year 10 months 24 days
Balance, end of year, Aggregate Intrinsic Value	$ 4,623,000
Closing price per share, ordinary shares (dollars per share)	$ 204.89
Unrecognized compensation cost	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Weighted-average fair value per SAR (dollars per share)	$ 78.47	$ 76.03	$ 45.85
Weighted-average volatility	49.43%	19.75%	18.94%
Weighted-average risk-free interest rate	0.15%	1.64%	2.72%
Dividend yield	0.00%	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise period	4 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise period	10 years

Share-Based Compensation and _7

Share-Based Compensation and Pensions - Joint Share Ownership Plan (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 20, 2023	Jan. 21, 2020	Dec. 31, 2020
Joint Share Ownership Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (shares)		565,630
Hurdle price per share (dollars per share)		$ 266
Shares issued, price per share (dollars per share)		205.89
Percentage of award subject to performance condition			20.00%
Grant date fair value (dollars per share)		$ 24.13
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Weighted-average volatility			18.66%
Weighted-average risk-free interest rate			1.55%
Dividend yield			0.00%
Unrecognized compensation cost			$ 9.4
Unrecognized compensation cost, period of recognition			2 years 1 month 6 days
Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (shares)		565,630
Chief Executive Officer | Joint Share Ownership Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		3 years
Grant date fair value		$ 13.6
Scenario, Forecast | Joint Share Ownership Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volume weighted average price per share, days	10 days
Consecutive trading days	10 days

Share-Based Compensation and _8

Share-Based Compensation and Pensions - Other Share-Based Compensation Plans (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Northshore/Atrium incentive plan | Minimum | Time-based restricted shares
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period	2 years
Northshore/Atrium incentive plan | Maximum | Time-based restricted shares
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period	3 years
StarStone incentive plan | Minimum | Time-based restricted shares
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period	2 years
StarStone incentive plan | Maximum | Time-based restricted shares
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period	3 years
Deferred compensation and ordinary share plan for non-employee directors | Director | Share-based compensation plans
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Restricted share units credited to the accounts of non-employee directors (shares)	7,204	5,976	5,691
Joint share ownership plan expense | Employee share purchase plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Discount rate from market price	15.00%
Maximum subscription rate	15.00%
Stock issued to employees (shares)	16,914	15,269	14,183

Share-Based Compensation and _9

Share-Based Compensation and Pensions - Pension Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plans	$ 11,791	$ 11,798	$ 11,434
Defined benefit plan	2,975	684	2,243
Total pension expense	14,766	12,482	$ 13,677
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, unfunded liability	6,900	8,900
Accrued liability, defined benefit plan	$ 6,900	$ 8,900

Income Taxation - Additional In

Income Taxation - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Bermuda income taxes, statutory rate	0.00%	0.00%	0.00%
Valuation allowance	$ 118,229,000	$ 117,390,000
Increase (decrease) in valuation allowance	800,000
Unrecognized tax benefits	0	0	$ 0
Accrued interest and penalties related to unrecognized tax benefits	$ 0	$ 0	$ 0

Income Taxation - Earnings befo

Income Taxation - Earnings before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Domestic (Bermuda)	$ 1,503,505	$ 576,338	$ (232,743)
Foreign	231,444	356,878	15,293
Total earnings (loss) before income taxes attributable to continuing operations	$ 1,734,949	$ 933,216	$ (217,450)

Income Taxation - Tax Expense f

Income Taxation - Tax Expense for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Domestic (Bermuda)									$ 0	$ 0	$ 0
Foreign									15,232	16,330	(917)
Total current tax expense									15,232	16,330	(917)
Deferred:
Domestic (Bermuda)									0	0	0
Foreign									8,595	(3,958)	(2,772)
Total deferred tax expense									8,595	(3,958)	(2,772)
Total income tax expense (benefit) attributable to continuing operations	$ (1,468)	$ 13,915	$ 16,652	$ (5,272)	$ (12,893)	$ 13,465	$ 7,698	$ 4,102	$ 23,827	$ 12,372	$ (3,689)

Income Taxation - Reconciliatio

Income Taxation - Reconciliation of Earnings before Income Taxes Computed by Applying Effective Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Earnings (loss) before income taxes	$ 1,734,949	$ 933,216	$ (217,450)
Bermuda income taxes at statutory rate	0.00%	0.00%	0.00%
Foreign income tax rate differential	1.20%	8.60%	0.60%
Change in valuation allowance	0.10%	(7.20%)	(1.80%)
U.S. base erosion and anti-abuse tax	0.00%	0.30%	(0.30%)
Other	0.10%	(0.40%)	3.20%
Effective tax rate	1.40%	1.30%	1.70%

Income Taxation - Components of

Income Taxation - Components of Deferred Tax Assets and Deferred Tax Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 141,459	$ 144,609
Insurance reserves	22,238	7,535
Unearned premiums	68	151
Provisions for bad debt	407	6,172
Defendant asbestos and environmental liabilities	121,006	140,000
Other deferred tax assets	16,696	3,230
Deferred tax assets	301,874	301,697
Valuation allowance	(118,229)	(117,390)
Deferred tax assets, net of valuation allowance	183,645	184,307
Deferred tax liabilities:
Unrealized gains on investments	(20,185)	(14,079)
Lloyd's underwriting profit taxable in future periods	(15,555)	(8,852)
Deferred policy acquisition cost	0	(8,267)
Other deferred tax liabilities	(9,242)	(13,390)
Deferred tax liabilities	(44,982)	(44,588)
Net deferred tax asset	$ 138,663	$ 139,719

Income Taxation - Deferred Tax

Income Taxation - Deferred Tax Ending Balance (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Net Deferred Tax Asset	$ 138,663	$ 139,719
United States
Segment Reporting Information [Line Items]
Net Deferred Tax Asset	156,730	154,700
United Kingdom
Segment Reporting Information [Line Items]
Net Deferred Tax Liability	(18,095)	(16,074)
Other
Segment Reporting Information [Line Items]
Net Deferred Tax Asset	$ 28	$ 1,093

Income Taxation - Net Operating

Income Taxation - Net Operating Loss Carryforwards (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Tax effect	$ 141,459	$ 144,609
Foreign Tax Authority | United States
Operating Loss Carryforwards [Line Items]
Loss Carryforwards	428,732
Tax effect	90,034
Foreign Tax Authority | United Kingdom
Operating Loss Carryforwards [Line Items]
Loss Carryforwards	185,230
Tax effect	35,194
Foreign Tax Authority | Luxembourg
Operating Loss Carryforwards [Line Items]
Loss Carryforwards	17,200
Tax effect	4,300
Foreign Tax Authority | Other
Operating Loss Carryforwards [Line Items]
Loss Carryforwards	48,683
Tax effect	$ 11,931

Related Party Transactions - St

Related Party Transactions - Stone Point Capital LLC (Details) $ in Thousands	Dec. 31, 2020USD ($)director	Oct. 01, 2019USD ($)	Apr. 01, 2019USD ($)	Oct. 01, 2018USD ($)	Dec. 31, 2020USD ($)director	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Jul. 31, 2012shares	Jun. 30, 2021USD ($)	Dec. 31, 2020USD ($)director	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Jan. 01, 2021	Nov. 06, 2013general_partner
Related Party Transaction [Line Items]
Number of newly elected board of directors | director	5				5										5
Ownership %	47.40%				47.40%				47.40%						47.40%	47.40%
Assumed business															$ 2,186,024	$ 1,586,307	$ 1,772,104
Adverse development cover		$ 59,000
Redeemable noncontrolling interest	$ 365,436				$ 365,436				$ 438,791						365,436	438,791	458,543
Related Party, Consolidated Balance Sheet [Abstract]
Available-for-sale, at fair value	3,658,895				3,658,895				1,666,387						3,658,895	1,666,387
Equities, at fair value	846,795				846,795				726,721						846,795	726,721
Investments in funds	4,244,034				4,244,034				2,518,031						4,244,034	2,518,031
Total investments	15,256,930				15,256,930				12,619,793						15,256,930	12,619,793
Cash and cash equivalents	901,152				901,152				624,472						901,152	624,472	535,809
Other assets	925,533				925,533				1,162,955						925,533	1,162,955
Other liabilities	$ 942,905				942,905				994,584						942,905	994,584
Related Party, Consolidated Statement of Earnings [Abstract]
Net investment income					61,530	$ 72,130	$ 94,443	$ 74,714	76,847	$ 81,502	$ 74,271	$ 75,651			302,817	308,271	261,698
Net realized and unrealized gains (losses)					803,467	500,005	967,608	(629,061)	153,477	145,060	260,669	452,760			1,642,019	1,011,966	(407,532)
NET EARNINGS (LOSS)					$ 834,655	$ 645,850	787,486	$ (540,618)	197,864	$ 126,559	$ 238,054	$ 365,742			$ 1,727,373	928,219	(212,272)
Scenario, Forecast
Related Party Transaction [Line Items]
Payments to acquire investments														$ 27,000
North Bay
Related Party Transaction [Line Items]
Ownership interest held by parent	59.00%				59.00%										59.00%
Northshore
Related Party Transaction [Line Items]
Percentage of shares owned in order to designate member of board of directors	50.00%				50.00%										50.00%
Right to designate board of directors if 50% or more of shares owned | director	1				1										1
Common shares subject to transfer restriction, term	18 months
SSHL
Related Party Transaction [Line Items]
Ownership interest held by parent	59.00%				59.00%										59.00%
Affiliated entity
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	$ 3,300,000				$ 3,300,000										$ 3,300,000
SSHL
Related Party Transaction [Line Items]
Number designated to board of directors | director	3				3										3
Trident | Affiliated entity
Related Party Transaction [Line Items]
Voting ordinary shares acquired (shares) | shares													1,635,986
Number of newly elected board of directors | general_partner																			1
Number of general partners | general_partner																			4
Redeemable noncontrolling interest	$ 350,200				$ 350,200				420,500						$ 350,200	420,500
Related Party, Consolidated Balance Sheet [Abstract]
Equities, at fair value	77,100				77,100										77,100
StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Equities, at fair value	103,914				103,914				121,794						103,914	121,794
Total investments	1,054,873				1,054,873				1,142,446						1,054,873	1,142,446
Cash and cash equivalents	23,933				23,933				54,080						23,933	54,080
Other assets	403				403				10						403	10
Other liabilities	745				745				4,710						745	4,710
Net investment	1,078,464				1,078,464				1,191,826						1,078,464	1,191,826
Related Party, Consolidated Statement of Earnings [Abstract]
Net investment income															16,325	8,733	7,424
Net realized and unrealized gains (losses)															23,750	26,631	207
NET EARNINGS (LOSS)															40,075	35,364	7,631
Starstone
Related Party Transaction [Line Items]
Assumed business		189,400
Reinsurance premium consideration		$ 189,400
Short-term Investments
Related Party, Consolidated Balance Sheet [Abstract]
Available-for-sale, at fair value	263,795				263,795				128,335						263,795	128,335
Fixed maturity investments, trading	5,129				5,129				51,490						5,129	51,490
Short-term Investments | StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Available-for-sale, at fair value	878				878				1,431						878	1,431
Fixed Maturities
Related Party, Consolidated Balance Sheet [Abstract]
Available-for-sale, at fair value	3,395,100				3,395,100				1,538,052						3,395,100	1,538,052
Fixed maturity investments, trading	4,594,892				4,594,892				6,143,335						4,594,892	6,143,335
Fixed Maturities | StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Available-for-sale, at fair value	227,397				227,397				160,303						227,397	160,303
Fixed maturity investments, trading	196,086				196,086				269,131						196,086	269,131
Hedge funds
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	2,638,339				2,638,339				1,121,904						2,638,339	1,121,904
Hedge funds | StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	19,844				19,844				18,993						19,844	18,993
Fixed income funds
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	552,541				552,541				481,039						552,541	481,039
Fixed income funds | StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	210,017				210,017				381,449						210,017	381,449
Private equity funds
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	363,103				363,103				323,496						363,103	323,496
Private equity funds | StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	37,262				37,262				34,858						37,262	34,858
CLO equities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	128,083				128,083				87,555						128,083	87,555
CLO equities | StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	38,658				38,658				32,560						38,658	32,560
CLO equity funds
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	166,523				166,523				87,509						166,523	87,509
CLO equity funds | StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	166,523				166,523				87,509						166,523	87,509
Private Debt | StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	27,016				27,016				16,312						27,016	16,312
Real estate fund | StonePoint And Affiliated Entities
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	$ 27,278				$ 27,278				$ 18,106						$ 27,278	$ 18,106
Stone Point | Affiliated entity
Related Party Transaction [Line Items]
Voting ordinary shares acquired, percent	8.80%				8.80%										8.80%
Trident | Scenario, Forecast
Related Party Transaction [Line Items]
Payments to acquire investments														$ 18,000
Trident | North Bay
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners	39.30%				39.30%										39.30%
Trident | Northshore | Subsequent Event
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners																		76.30%
Trident | SSHL
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners	39.30%				39.30%										39.30%
Trident | SSHL
Related Party Transaction [Line Items]
Number designated to board of directors | director	2				2										2
Trident | North Bay
Related Party Transaction [Line Items]
Payments to acquire investments				$ 53,100
Dowling | North Bay
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners	1.70%				1.70%										1.70%
Dowling | Northshore | Subsequent Event
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners																		1.60%
Dowling | Core Specialty | Subsequent Event
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners																		0.40%
Dowling | SSHL
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners	1.70%				1.70%										1.70%
Core Specialty | Northshore | Subsequent Event
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners																		13.80%
North Bay | Northshore
Related Party Transaction [Line Items]
Ownership interest held by parent	92.10%				92.10%										92.10%
North Bay | SSHL
Related Party Transaction [Line Items]
Ownership interest held by parent	100.00%				100.00%										100.00%
North Bay Shareholders | North Bay
Related Party Transaction [Line Items]
Payments to acquire investments			$ 48,000	$ 135,000
Mitchell International | Affiliated entity
Related Party, Consolidated Balance Sheet [Abstract]
Investments in funds	$ 26,900				$ 26,900										$ 26,900		$ 25,000
Sound Point Capital | Affiliated entity | Senior Loans
Related Party Transaction [Line Items]
Note receivable							$ 10,000
Term loan facility, term							2 years
Core Specialty
Related Party Transaction [Line Items]
Ownership %																		25.23%
Core Specialty | Subsequent Event
Related Party Transaction [Line Items]
Ownership %																		25.23%

Related Party Transactions - Ka

Related Party Transactions - KaylaRe (Details) - USD ($) $ in Thousands	May 14, 2018	Dec. 15, 2016	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 13, 2018
Related Party Transaction [Line Items]
Ownership percentage			47.40%				47.40%				47.40%	47.40%
Fee income due to Enstar Limited													$ 1,453
Transactions under KaylaRe-StarStone QS:
Ceded premium earned											$ (157,826)	$ (145,483)	(166,334)
Net incurred losses and LAE			$ 76,248	$ 109,686	$ 186,692	$ 43,300	$ 48,068	$ 163,258	$ 146,554	$ 256,299	415,926	614,179	323,722
Acquisition costs			$ 38,202	$ 37,708	$ 49,067	$ 46,043	$ 78,417	$ 33,310	$ 51,081	$ 77,801	$ 171,020	$ 240,609	177,855
KaylaRe
Related Party Transaction [Line Items]
Initial capital raise		$ 620,000
KaylaRe Transactions With Starstone
Transactions under KaylaRe-StarStone QS:
Ceded premium earned													(52,651)
Net incurred losses and LAE													31,654
Acquisition costs													18,774
Affiliated entity | KaylaRe
Transactions under KaylaRe-StarStone QS:
Total net earnings (loss)													$ (770)
KaylaRe
Related Party Transaction [Line Items]
Ownership percentage														48.20%
KaylaRe
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	2,007,017
Ordinary Shares | KaylaRe
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	1,501,778
Ordinary Shares | KaylaRe | Hillhouse
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	1,204,353
Ordinary Shares | KaylaRe | Trident
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	285,986
Series E non-voting convertible ordinary shares | KaylaRe
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	505,239
Series E non-voting convertible ordinary shares | KaylaRe | Hillhouse
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	505,239
Series E non-voting convertible ordinary shares | KaylaRe | Minority Shareholder
Related Party Transaction [Line Items]
Number of Enstar ordinary shares issued (shares)	11,439

Related Party Transactions - Hi

Related Party Transactions - Hillhouse (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Feb. 21, 2021	Dec. 31, 2019
Related Party Transaction [Line Items]
Investments in funds	$ 4,244,034		$ 2,518,031
Ownership %	47.40%		47.40%
Series C non-voting convertible ordinary shares
Related Party Transaction [Line Items]
Warrants outstanding (shares)	175,901
Warrants, exercise price (dollars per share)	$ 115
Affiliated entity
Related Party Transaction [Line Items]
Investments in funds	$ 3,300,000
Hillhouse Affiliates | Affiliated entity
Related Party Transaction [Line Items]
Voting ordinary shares acquired, percent	9.40%
Economic ownership percentage	16.60%
Hillhouse
Related Party Transaction [Line Items]
Investments in funds	$ 2,734,666		$ 1,151,601
Hillhouse | Affiliated entity
Related Party Transaction [Line Items]
Investments in funds	403,580		155,377
Increase in other investments	300,000
Management fees	394,000
Hillhouse | Affiliated entity | Scenario, Forecast
Related Party Transaction [Line Items]
Performance fee waived		$ 100,000
Hillhouse | Hillhouse Affiliates | Affiliated entity
Related Party Transaction [Line Items]
Investments in funds	$ 851,435		327,799
Hillhouse InRe Fund, L.P. | Fixed Income Securities | Affiliated entity
Related Party Transaction [Line Items]
Percent of funds invested	(5.00%)
Hillhouse InRe Fund, L.P. | North American Equities | Affiliated entity
Related Party Transaction [Line Items]
Percent of funds invested	20.00%
Hillhouse InRe Fund, L.P. | International Equities | Affiliated entity
Related Party Transaction [Line Items]
Percent of funds invested	67.00%
Hillhouse InRe Fund, L.P. | Financing, Derivatives And Other Items | Affiliated entity
Related Party Transaction [Line Items]
Percent of funds invested	18.00%
InRe Fund | Hillhouse | Affiliated entity
Related Party Transaction [Line Items]
Investments in funds	$ 2,365,158		918,633
Other funds | Hillhouse | Affiliated entity
Related Party Transaction [Line Items]
Investments in funds	$ 369,508		$ 232,968

Related Party Transactions - Mo

Related Party Transactions - Monument (Details) $ in Thousands, € in Millions	3 Months Ended								12 Months Ended			39 Months Ended	51 Months Ended
	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2020USD ($)	May 31, 2019USD ($)	May 31, 2019EUR (€)
Related Party Transaction [Line Items]
Investment in common and preferred shares									$ 33,000	$ 69,213	$ 155,440
Ownership percentage	47.40%				47.40%				47.40%	47.40%		47.40%	47.40%
Equity method investments	$ 832,295				$ 326,277				$ 832,295	$ 326,277		$ 326,277	$ 832,295
Earnings from equity method investments	$ 85,844	$ 149,065	$ (8,790)	$ 12,450	$ 11,722	$ 17,703	$ 17,713	$ 8,772	$ 238,569	$ 55,910	42,147
Fee income due to Enstar Limited											$ 1,453
Monument Re
Related Party Transaction [Line Items]
Investment in common and preferred shares												$ 26,600	$ 59,600
Voting ordinary shares acquired, percent	20.00%								20.00%				20.00%
Ownership percentage	23.00%				23.50%				23.00%	23.50%		23.50%	23.00%
Equity method investments	$ 193,716				$ 60,598				$ 193,716	$ 60,598		$ 60,598	$ 193,716
Earnings from equity method investments									88,300	$ 19,800
Fee income due to Enstar Limited									$ 100
Transfer Of Life Assurance Policies | Subsidiary of Monument
Related Party Transaction [Line Items]
Policy benefits for life contracts														$ 99,100	€ 88.8
Assets related to future policy benefits														$ (101,600)	€ (91.1)

Related Party Transactions - Cl

Related Party Transactions - Clear Spring (Details) - USD ($)	Jan. 01, 2017	Dec. 31, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Capitalized amount	$ 56,000,000
Ownership percentage		47.40%	47.40%				47.40%				47.40%	47.40%
Sale of equity method investment		$ 12,200,000									$ 12,200,000	$ 0	$ 0
Gain on sale of equity method investment			$ 600,000
Equity method investments		832,295,000	832,295,000				$ 326,277,000				832,295,000	326,277,000
Earnings from equity method investments			85,844,000	$ 149,065,000	$ (8,790,000)	$ 12,450,000	11,722,000	$ 17,703,000	$ 17,713,000	$ 8,772,000	238,569,000	55,910,000	42,147,000
Balances under ceding quota share:
Reinsurance balances recoverable		2,089,163,000	2,089,163,000				2,181,134,000				2,089,163,000	2,181,134,000
Balances under assuming quota share:
Losses and LAE		10,593,282,000	10,593,282,000				9,868,404,000				10,593,282,000	9,868,404,000	9,048,796,000	$ 7,100,488,000
Funds held by reinsured companies		$ 635,819,000	635,819,000				475,732,000				635,819,000	475,732,000
Amounts under ceding quota share:
Net incurred losses and LAE											154,926,000	33,260,000	0
Acquisition costs			38,202,000	37,708,000	49,067,000	46,043,000	78,417,000	33,310,000	51,081,000	77,801,000	171,020,000	240,609,000	177,855,000
Transactions under assuming quota share:
Net incurred losses and loss adjustment expenses			$ 76,248,000	$ 109,686,000	$ 186,692,000	$ 43,300,000	$ 48,068,000	$ 163,258,000	$ 146,554,000	$ 256,299,000	$ 415,926,000	$ 614,179,000	323,722,000
Clear Spring
Related Party Transaction [Line Items]
Ownership percentage		0.00%	0.00%				20.00%				0.00%	20.00%
Equity method investments		$ 0	$ 0				$ 10,645,000				$ 0	$ 10,645,000
Earnings from equity method investments											$ 1,000,000	600,000
Clear Spring
Related Party Transaction [Line Items]
Percentage reinsured of certain businesses	25.00%
Balances under assuming quota share:
Losses and LAE							6,135,000					6,135,000
Unearned premiums							13,000					13,000
Funds held by reinsured companies							8,611,000					8,611,000
Equity method investee | Clear Spring
Related Party Transaction [Line Items]
Ownership percentage		20.00%	20.00%								20.00%
Affiliated entity | Clear Spring
Amounts under ceding quota share:
Acquisition costs											$ (11,000)	92,000	1,836,000
Transactions under assuming quota share:
Premium earned											(15,000)	3,749,000	7,380,000
Net incurred losses and loss adjustment expenses											1,014,000	(2,202,000)	(4,536,000)
Total income impact											3,918,000	(6,616,000)	(3,334,000)
Starstone | Clear Spring
Related Party Transaction [Line Items]
Equity method investments		$ 0	$ 0				10,600,000				0	10,600,000
Percentage reinsured of certain businesses	33.30%
Starstone | Equity method investee | Clear Spring
Balances under ceding quota share:
Reinsurance balances recoverable							22,812,000					22,812,000
Prepaid reinsurance premiums							51,000					51,000
Ceded other liabilities							3,616,000					3,616,000
Ceded acquisition costs							$ 21,000					21,000
Starstone | Affiliated entity | Clear Spring
Amounts under ceding quota share:
Ceded premium earned											122,000	(14,994,000)	(29,520,000)
Net incurred losses and LAE											2,730,000	6,567,000	18,143,000
Acquisition costs											$ 56,000	$ 356,000	$ 7,035,000

Related Party Transactions - Am

Related Party Transactions - AmTrust (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended								12 Months Ended
	Dec. 31, 2019	Nov. 30, 2018	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Investment in common and preferred shares											$ 33,000	$ 69,213	$ 155,440
Fees and commission income													1,453
Net investment income			$ 61,530	$ 72,130	$ 94,443	$ 74,714	$ 76,847	$ 81,502	$ 74,271	$ 75,651	302,817	308,271	261,698
Net realized and unrealized gains (losses)			803,467	500,005	967,608	(629,061)	153,477	145,060	260,669	452,760	1,642,019	1,011,966	(407,532)
NET EARNINGS (LOSS)			834,655	$ 645,850	$ 787,486	$ (540,618)	197,864	$ 126,559	$ 238,054	$ 365,742	1,727,373	928,219	(212,272)
Evergreen Parent L.P. | Affiliated entity
Related Party Transaction [Line Items]
Investment in common and preferred shares	$ 25,900	$ 200,000
Ownership of equity interest		8.50%
Fees and commission income												3,300
AmTrust | Affiliated entity
Related Party Transaction [Line Items]
Indirect investment	$ 240,100		$ 230,300				$ 240,100				230,300	240,100
Net investment income											7,365	7,667	299
Net realized and unrealized gains (losses)											(11,183)	10,086	0
NET EARNINGS (LOSS)											$ (3,818)	$ 17,753	$ 299
AmTrust | Affiliated entity
Related Party Transaction [Line Items]
Voting ordinary shares acquired, percent		45.00%
Evergreen Parent L.P. | Trident Pine | Affiliated entity
Related Party Transaction [Line Items]
Ownership of equity interest		21.80%

Related Party Transactions - Ci

Related Party Transactions - Citco (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	Jun. 30, 2018	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Ownership %		47.40%				47.40%				47.40%	47.40%
Net additional subscriptions										$ 975,024	$ 794,613	$ 900,262
Investments in funds		$ 4,244,034				$ 2,518,031				4,244,034	2,518,031
Earnings from equity method investments		85,844	$ 149,065	$ (8,790)	$ 12,450	$ 11,722	$ 17,703	$ 17,713	$ 8,772	238,569	$ 55,910	$ 42,147
Affiliated entity
Related Party Transaction [Line Items]
Investments in funds		$ 3,300,000								$ 3,300,000
CTCO Holdings Limited | Citco
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners		6.20%								6.20%
CTCO Holdings Limited | Convertible Preferred Stock | Citco
Related Party Transaction [Line Items]
Ownership interest held by noncontrolling owners		15.40%								15.40%
Citco | Trident | Affiliated entity
Related Party Transaction [Line Items]
Net additional subscriptions	$ 50,000
Voting ordinary shares acquired, percent		3.40%								3.40%
Citco
Related Party Transaction [Line Items]
Ownership %						31.90%					31.90%
Investments in funds		$ 53,000				$ 51,700				$ 53,000	$ 51,700
Earnings from equity method investments										$ 2,200	$ 2,700
Citco | Ordinary Shares
Related Party Transaction [Line Items]
Ownership %		31.90%								31.90%

Related Party Transactions - En

Related Party Transactions - EnhanzedRe (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Equity method investments	$ 832,295				$ 326,277				$ 832,295	$ 326,277
Ownership percentage	47.40%				47.40%				47.40%	47.40%
Earnings from equity method investments	$ 85,844	$ 149,065	$ (8,790)	$ 12,450	$ 11,722	$ 17,703	$ 17,713	$ 8,772	$ 238,569	$ 55,910	$ 42,147
Balances under ceding quota share:
Reinsurance balances recoverable	2,089,163				2,181,134				2,089,163	2,181,134
Funds held	635,819				475,732				635,819	475,732
Insurance balances payables	494,412				420,546				494,412	420,546
Other assets	925,533				1,162,955				925,533	1,162,955
Amounts under ceding quota share:
Ceded premium earned									(157,826)	(145,483)	(166,334)
Net incurred losses and LAE									154,926	33,260	0
Acquisition costs	38,202	37,708	49,067	46,043	78,417	33,310	51,081	77,801	171,020	240,609	177,855
Net investment income	61,530	72,130	94,443	74,714	76,847	81,502	74,271	75,651	302,817	308,271	261,698
Net realized and unrealized gains (losses)	803,467	500,005	967,608	(629,061)	153,477	145,060	260,669	452,760	1,642,019	1,011,966	(407,532)
Fees and commission income											1,453
NET EARNINGS (LOSS)	834,655	$ 645,850	$ 787,486	(540,618)	197,864	$ 126,559	$ 238,054	$ 365,742	1,727,373	928,219	(212,272)
Non-life Run-off
Balances under ceding quota share:
Reinsurance balances recoverable	1,599,869				1,724,989				1,599,869	1,724,989
Amounts under ceding quota share:
Net incurred losses and LAE									154,926	33,260	$ 0
Enhanzed Re | Enstar
Related Party Transaction [Line Items]
Equity method investments				$ 154,100
Ownership percentage											47.40%
Uncalled amount of investment	68,700								68,700
Enhanzed Re | Allianz
Related Party Transaction [Line Items]
Ownership percentage											24.90%
Enhanzed Re | Hillhouse
Related Party Transaction [Line Items]
Ownership percentage											27.70%
Enhanzed Re
Related Party Transaction [Line Items]
Equity method investments	$ 330,289				$ 182,856				$ 330,289	$ 182,856
Ownership percentage	47.40%				47.40%				47.40%	47.40%
Earnings from equity method investments									$ 147,300	$ 28,900
Enhanzed Re | Non-life Run-off
Amounts under ceding quota share:
Net incurred losses and LAE									137,000
Enhanzed Re | Affiliated entity
Related Party Transaction [Line Items]
Equity method investments											$ 470,000
Balances under ceding quota share:
Reinsurance balances recoverable	$ 208,379				$ 59,601				208,379	59,601
Funds held	193,981				50,089				193,981	50,089
Insurance balances payables	1,276				1,443				1,276	1,443
Other assets	$ 730				$ 1,033				730	1,033
Amounts under ceding quota share:
Ceded premium earned									(391)	0
Net incurred losses and LAE									(5,977)	0
Acquisition costs									169	73
Net investment income									(4,272)	0
Net realized and unrealized gains (losses)									(740)	0
Other income									2,617	0
Fees and commission income									572	749
NET EARNINGS (LOSS)									(8,022)	822
Change in unrealized gains (losses) on AFS investments									$ (2,729)	$ 0
Enhanzed Re | Zurich
Related Party Transaction [Line Items]
Percentage ceded									10.00%

Related Party Disclosures - Cor

Related Party Disclosures - Core Specialty (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Nov. 30, 2020	Dec. 31, 2017
Related Party Transaction [Line Items]
Equity method investments	$ 832,295				$ 326,277				$ 832,295	$ 326,277
Funds held by reinsured companies	635,819				475,732				635,819	475,732
Other assets	925,533				1,162,955				925,533	1,162,955
Losses and LAE	10,593,282				9,868,404				10,593,282	9,868,404	$ 9,048,796		$ 7,100,488
Insurance and reinsurance balances payable	494,412				420,546				494,412	420,546
Other liabilities	942,905				994,584				942,905	994,584
Reinsurance balances recoverable on paid and unpaid losses	2,089,163				2,181,134				2,089,163	2,181,134
Net premiums earned	108,146	$ 161,724	$ 142,871	$ 159,351	185,336	$ 175,802	$ 190,962	$ 251,947	572,092	804,047	695,779
Net incurred losses and loss adjustment expenses									(154,926)	(33,260)	0
Acquisition costs	38,202	37,708	49,067	46,043	78,417	33,310	51,081	77,801	171,020	240,609	177,855
Fees and commission income											1,453
NET EARNINGS (LOSS)	834,655	$ 645,850	$ 787,486	$ (540,618)	$ 197,864	$ 126,559	$ 238,054	$ 365,742	1,727,373	$ 928,219	$ (212,272)
Discontinued operations, disposed of by sale | StarStone US
Related Party Transaction [Line Items]
Consideration received	281,989								281,989			$ 235,000
Initial cash consideration received												51,500
Cash consideration received												$ 47,000
Core Specialty
Related Party Transaction [Line Items]
Equity method investments	235,000								235,000
Affiliated entity | Core Specialty
Related Party Transaction [Line Items]
Cash consideration repayable	4,500								4,500
Core Specialty | Affiliated entity
Related Party Transaction [Line Items]
NET EARNINGS (LOSS)									3,315
Core Specialty | Affiliated entity | Balances under assuming quota share, LTP and ADC reinsurances
Related Party Transaction [Line Items]
Funds held by reinsured companies	58,086								58,086
Other assets	38,846								38,846
Losses and LAE	682,637								682,637
Insurance and reinsurance balances payable	24,806								24,806
Other liabilities	5,003								5,003
Net premiums earned									76
Net incurred losses and loss adjustment expenses									(1,223)
Acquisition costs									458
Core Specialty | Affiliated entity | Balances under ceding reinsurances
Related Party Transaction [Line Items]
Reinsurance balances recoverable on paid and unpaid losses	1,736								1,736
Core Specialty | Affiliated entity | Balances under service agreements
Related Party Transaction [Line Items]
Other assets	6,727								6,727
Other liabilities	328								328
Fees and commission income									4,004
Core Specialty | Affiliated entity | Balances under sale and recapitalization agreement
Related Party Transaction [Line Items]
Other liabilities	$ 4,512								$ 4,512

Dividend Restrictions and Sta_3

Dividend Restrictions and Statutory Financial Information - Parent Company Dividends (Details)	12 Months Ended
	Dec. 31, 2020
Series D Preferred Shares
Statutory Accounting Practices [Line Items]
Dividend rate	7.00%
Series E Preferred Shares
Statutory Accounting Practices [Line Items]
Dividend rate	7.00%
Bermuda
Statutory Accounting Practices [Line Items]
Target statutory capital and surplus percent	120.00%

Dividend Restrictions and Sta_4

Dividend Restrictions and Statutory Financial Information - Subsidiary Statutory Financial Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Bermuda
Statutory Accounting Practices [Line Items]
Required	$ 2,711,687	$ 2,138,395
Actual	5,565,429	4,016,663
Statutory Income	1,850,913	643,683	$ 29,486
U.K.
Statutory Accounting Practices [Line Items]
Required	803,685	837,104
Actual	1,224,208	1,532,751
Statutory Income	43,219	154,644	(52,936)
U.S.
Statutory Accounting Practices [Line Items]
Required	185,904	364,507
Actual	554,339	861,379
Statutory Income	(67,477)	121,406	(75,005)
Europe
Statutory Accounting Practices [Line Items]
Required	95,746	94,334
Actual	214,115	229,344
Statutory Income	(983)	11,816	(17,611)
Australia
Statutory Accounting Practices [Line Items]
Required	18,858	18,110
Actual	58,531	37,815
Statutory Income	$ (1,722)	$ 4,847	$ 1,761

Dividend Restrictions and Sta_5

Dividend Restrictions and Statutory Financial Information - Subsidiary Statutory Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statutory Accounting Practices [Line Items]
Restricted net assets of consolidated subsidiaries	$ 3,800
Bermuda
Statutory Accounting Practices [Line Items]
Minimum liquidity ratio percent (not less than)	75.00%
Minimum percentage reduction in total statutory capital without prior approval of Bermuda regulator (percent) (or more)	15.00%
Maximum percentage reduction in total statutory capital without prior approval of Bermuda regulator (percent) (or more)	25.00%
Minimum solvency requirement	$ 2,900	$ 1,900
United Kingdom
Statutory Accounting Practices [Line Items]
Minimum capital requirements	420.5	695.6
United States
Statutory Accounting Practices [Line Items]
Minimum levels of risk-based capital	362.2	488.3
Liechtenstein
Statutory Accounting Practices [Line Items]
Minimum solvency requirement	$ 97.6	$ 119

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2019
Concentration Risk [Line Items]
Funds held by reinsured companies	$ 635,819		$ 475,732
Renewal lease term	5 years
Termination period	1 year
Rent expense		$ 11,300
Minimum
Concentration Risk [Line Items]
Remaining lease terms	1 year
Maximum
Concentration Risk [Line Items]
Remaining lease terms	36 years
Limited Parental Guarantee
Concentration Risk [Line Items]
Total parental guarantees	$ 1,500,000		$ 1,000,000
Reinsurer concentration risk | Reinsurance balances recoverable
Concentration Risk [Line Items]
Funds held by reinsured companies	955,000
United States
Concentration Risk [Line Items]
Exposure to government	1,400,000
Other investments
Concentration Risk [Line Items]
Commitments, unfunded	975,500
Equity Method Investments
Concentration Risk [Line Items]
Commitments, unfunded	68,700
Fixed maturity investments, trading
Concentration Risk [Line Items]
Commitments, unfunded	$ 5,000

Commitments and Contingencies_2

Commitments and Contingencies - Leases - Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lease cost:
Operating lease cost	$ 12,720	$ 13,627
Short-term lease cost	246	0
Total lease cost	12,966	13,627
Sub-lease income	(553)	(542)
Total net lease cost	12,413	13,085
Other information:
Operating cash paid for amounts included in the measurement of lease liabilities	13,421	11,129
Non-cash activity: right-of-use assets relating to leases	$ 295	$ 57,536
Weighted-average remaining lease term	6 years 1 month 6 days	6 years 3 months 18 days
Weighted-average discount rate	6.50%	6.30%

Commitments and Contingencies_3

Commitments and Contingencies - Leases - Balance Sheet Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Right-of-use assets	$ 32,297	$ 46,747
Current lease liabilities	7,959	11,403
Non-current lease liabilities	27,064	$ 34,785
Starstone International
Lessee, Lease, Description [Line Items]
Operating lease, impairment loss	3,500
Atrium | Held-for-sale or disposed of by sale, not discontinued operations
Lessee, Lease, Description [Line Items]
Right-of-use asset, held-for-sale	1,000
Lease liability, held-for-sale	$ 800

Commitments and Contingencies_4

Commitments and Contingencies - Leases - Operating Lease Liabilities (Details) $ in Thousands	Dec. 31, 2020USD ($)
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 9,774
2022	8,099
2023	7,267
2024	5,561
2025	4,534
2026 and beyond	8,577
Total lease payments	43,812
Less: Imputed interest	(8,789)
Present value of lease liabilities	$ 35,023

Segment Information - Additiona

Segment Information - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020Segment
Segment Reporting [Abstract]
Number of segments	3

Segment Information - Summary o

Segment Information - Summary of Operations by Segment (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Gross premiums written									$ 551,983	$ 658,653	$ 817,532
Net premiums written									432,824	545,053	654,347
Net premiums earned	$ 108,146	$ 161,724	$ 142,871	$ 159,351	$ 185,336	$ 175,802	$ 190,962	$ 251,947	572,092	804,047	695,779
Net incurred losses and LAE	(76,248)	(109,686)	(186,692)	(43,300)	(48,068)	(163,258)	(146,554)	(256,299)	(415,926)	(614,179)	(323,722)
Acquisition costs	(38,202)	(37,708)	(49,067)	(46,043)	(78,417)	(33,310)	(51,081)	(77,801)	(171,020)	(240,609)	(177,855)
Operating expenses									(295,921)	(274,835)	(274,645)
Underwriting income (loss)									(310,775)	(325,576)	(80,443)
Net investment income	61,530	72,130	94,443	74,714	76,847	81,502	74,271	75,651	302,817	308,271	261,698
Net realized and unrealized gains	803,467	500,005	967,608	(629,061)	153,477	145,060	260,669	452,760	1,642,019	1,011,966	(407,532)
Fees and commission income	14,121	10,787	10,010	7,528	9,522	6,437	6,017	6,477	42,446	28,453	35,088
Other income (losses)	33,372	48,404	(1,087)	20,443	21,703	822	8,831	5,714	101,132	37,070	34,073
Corporate expenses									(205,558)	(138,249)	(74,141)
Interest income (expense)									(59,308)	(52,541)	(25,696)
Net foreign exchange gains (losses)	(15,018)	(8,156)	(5,158)	11,939	(12,186)	13,665	2,579	3,854	(16,393)	7,912	(2,644)
EARNINGS (LOSS) BEFORE INCOME TAXES	731,902	506,669	814,080	(556,271)	177,915	114,405	231,982	353,004	1,496,380	877,306	(259,597)
Income tax benefit (expense)	1,468	(13,915)	(16,652)	5,272	12,893	(13,465)	(7,698)	(4,102)	(23,827)	(12,372)	3,689
Earnings (losses) from equity method investments	85,844	149,065	(8,790)	12,450	11,722	17,703	17,713	8,772	238,569	55,910	42,147
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	819,214	641,819	788,638	(538,549)	202,530	118,643	241,997	357,674	1,711,122	920,844	(213,761)
Net earnings from discontinued operations, net of income taxes	15,441	4,031	(1,152)	(2,069)	(4,666)	7,916	(3,943)	8,068	16,251	7,375	1,489
NET EARNINGS (LOSS)	834,655	645,850	787,486	(540,618)	197,864	126,559	238,054	365,742	1,727,373	928,219	(212,272)
Net loss attributable to noncontrolling interest	(3,131)	(21,912)	19,992	32,722	4,900	109	2,713	2,148	27,671	9,870	62,051
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	831,524	623,938	807,478	(507,896)	202,764	126,668	240,767	367,890	1,755,044	938,089	(150,221)
Dividends on preferred shares	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(9,139)	(35,700)	(35,914)	(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$ 822,599	$ 615,013	$ 798,553	$ (516,821)	$ 193,839	$ 117,743	$ 231,842	$ 358,751	1,719,344	902,175	(162,354)
Non-life Run-off
Segment Reporting Information [Line Items]
Net incurred losses and LAE									(44,995)	(51,625)	306,067
Atrium
Segment Reporting Information [Line Items]
Net incurred losses and LAE									$ (87,226)	$ (77,276)	$ (69,810)
Underwriting ratios:
Loss ratio									49.70%	47.10%	47.70%
Acquisition expense ratio									34.00%	34.70%	34.60%
Operating expense ratio									7.50%	8.80%	12.20%
Combined ratio									91.20%	90.60%	94.50%
StarStone
Segment Reporting Information [Line Items]
Net incurred losses and LAE									$ (266,738)	$ (469,240)	$ (543,080)
Underwriting ratios:
Loss ratio									83.80%	104.00%	105.40%
Acquisition expense ratio									28.50%	24.20%	23.40%
Operating expense ratio									25.80%	13.50%	19.10%
Combined ratio									138.10%	141.70%	147.90%
Operating Segments | Non-life Run-off
Segment Reporting Information [Line Items]
Gross premiums written									$ 5,191	$ (25,069)	$ (8,910)
Net premiums written									2,987	(25,338)	(9,217)
Net premiums earned									58,695	168,496	9,427
Net incurred losses and LAE									(44,995)	(51,625)	306,067
Acquisition costs									(20,177)	(73,642)	(4,006)
Operating expenses									(200,990)	(199,756)	(158,731)
Underwriting income (loss)									(207,467)	(156,527)	152,757
Net investment income									282,048	275,236	226,287
Net realized and unrealized gains									1,627,526	968,350	(381,712)
Fees and commission income									19,462	18,293	16,466
Other income (losses)									99,940	34,809	35,978
Corporate expenses									(97,727)	(70,689)	(39,093)
Interest income (expense)									(67,195)	(62,055)	(30,616)
Net foreign exchange gains (losses)									(13,214)	9,918	2,534
EARNINGS (LOSS) BEFORE INCOME TAXES									1,643,373	1,017,335	(17,399)
Income tax benefit (expense)									(17,412)	(7,250)	3,581
Earnings (losses) from equity method investments									238,569	56,128	42,147
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS									1,864,530	1,066,213	28,329
Net earnings from discontinued operations, net of income taxes									0	0	0
NET EARNINGS (LOSS)									1,864,530	1,066,213	28,329
Net loss attributable to noncontrolling interest									1,597	(6,409)	(3,107)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR									1,866,127	1,059,804	25,222
Dividends on preferred shares									0	0	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS									1,866,127	1,059,804	25,222
Operating Segments | Atrium
Segment Reporting Information [Line Items]
Gross premiums written									206,656	192,373	171,494
Net premiums written									183,194	172,356	153,488
Net premiums earned									175,393	164,059	146,315
Net incurred losses and LAE									(87,226)	(77,276)	(69,810)
Acquisition costs									(59,611)	(56,956)	(50,646)
Operating expenses									(13,078)	(14,452)	(17,777)
Underwriting income (loss)									15,478	15,375	8,082
Net investment income									5,542	7,049	5,686
Net realized and unrealized gains									4,165	6,195	(3,251)
Fees and commission income									22,984	10,160	18,622
Other income (losses)									131	140	162
Corporate expenses									(21,522)	(13,825)	(6,921)
Interest income (expense)									0	0	0
Net foreign exchange gains (losses)									4,327	(504)	(3,394)
EARNINGS (LOSS) BEFORE INCOME TAXES									31,105	24,590	18,986
Income tax benefit (expense)									(4,122)	(4,033)	(3,732)
Earnings (losses) from equity method investments									0	0	0
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS									26,983	20,557	15,254
Net earnings from discontinued operations, net of income taxes									0	0	0
NET EARNINGS (LOSS)									26,983	20,557	15,254
Net loss attributable to noncontrolling interest									(11,059)	(8,432)	(6,257)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR									15,924	12,125	8,997
Dividends on preferred shares									0	0	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS									15,924	12,125	8,997
Operating Segments | StarStone
Segment Reporting Information [Line Items]
Gross premiums written									326,695	472,815	622,570
Net premiums written									233,202	379,523	478,009
Net premiums earned									318,115	451,112	515,163
Net incurred losses and LAE									(266,738)	(469,240)	(543,080)
Acquisition costs									(90,797)	(109,369)	(120,517)
Operating expenses									(81,853)	(60,627)	(98,137)
Underwriting income (loss)									(121,273)	(188,124)	(246,571)
Net investment income									27,443	34,396	27,000
Net realized and unrealized gains									10,328	31,572	(12,320)
Fees and commission income									0	0	0
Other income (losses)									3,734	329	(550)
Corporate expenses									(42,011)	(7,790)	0
Interest income (expense)									(2,110)	(475)	(103)
Net foreign exchange gains (losses)									(10,140)	(1,505)	(2,832)
EARNINGS (LOSS) BEFORE INCOME TAXES									(134,029)	(131,597)	(235,376)
Income tax benefit (expense)									(902)	(1,004)	3,892
Earnings (losses) from equity method investments									0	(218)	0
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS									(134,931)	(132,819)	(231,484)
Net earnings from discontinued operations, net of income taxes									16,251	7,375	1,489
NET EARNINGS (LOSS)									(118,680)	(125,444)	(229,995)
Net loss attributable to noncontrolling interest									37,133	24,711	71,415
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR									(81,547)	(100,733)	(158,580)
Dividends on preferred shares									0	0	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS									(81,547)	(100,733)	(158,580)
Other
Segment Reporting Information [Line Items]
Gross premiums written									13,441	18,534	32,378
Net premiums written									13,441	18,512	32,067
Net premiums earned									19,889	20,380	24,874
Net incurred losses and LAE									(16,967)	(16,038)	(16,899)
Acquisition costs									(435)	(642)	(2,686)
Operating expenses									0	0	0
Underwriting income (loss)									2,487	3,700	5,289
Net investment income									(12,216)	(8,410)	2,725
Net realized and unrealized gains									0	5,849	(10,249)
Fees and commission income									0	0	0
Other income (losses)									(2,673)	1,792	(1,517)
Corporate expenses									(44,298)	(45,945)	(28,127)
Interest income (expense)									9,997	9,989	5,023
Net foreign exchange gains (losses)									2,634	3	1,048
EARNINGS (LOSS) BEFORE INCOME TAXES									(44,069)	(33,022)	(25,808)
Income tax benefit (expense)									(1,391)	(85)	(52)
Earnings (losses) from equity method investments									0	0	0
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS									(45,460)	(33,107)	(25,860)
Net earnings from discontinued operations, net of income taxes									0	0	0
NET EARNINGS (LOSS)									(45,460)	(33,107)	(25,860)
Net loss attributable to noncontrolling interest									0	0	0
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR									(45,460)	(33,107)	(25,860)
Dividends on preferred shares									(35,700)	(35,914)	(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS									$ (81,160)	$ (69,021)	$ (37,993)

Segment Information - Gross Pre

Segment Information - Gross Premiums Written by Geographical Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Gross, premiums written	$ 551,983	$ 658,653	$ 817,532
United States
Segment Reporting Information [Line Items]
Gross, premiums written	182,925
United Kingdom
Segment Reporting Information [Line Items]
Gross, premiums written	118,882
Europe
Segment Reporting Information [Line Items]
Gross, premiums written	83,501
Asia
Segment Reporting Information [Line Items]
Gross, premiums written	68,096
Rest of World
Segment Reporting Information [Line Items]
Gross, premiums written	$ 98,579
Geographic concentration risk | Gross premiums written
Segment Reporting Information [Line Items]
Gross premiums written (percent)	100.00%
Geographic concentration risk | Gross premiums written | United States
Segment Reporting Information [Line Items]
Gross premiums written (percent)	33.20%
Geographic concentration risk | Gross premiums written | United Kingdom
Segment Reporting Information [Line Items]
Gross premiums written (percent)	21.50%
Geographic concentration risk | Gross premiums written | Europe
Segment Reporting Information [Line Items]
Gross premiums written (percent)	15.10%
Geographic concentration risk | Gross premiums written | Asia
Segment Reporting Information [Line Items]
Gross premiums written (percent)	12.30%
Geographic concentration risk | Gross premiums written | Rest of World
Segment Reporting Information [Line Items]
Gross premiums written (percent)	17.90%
Operating Segments | Non-life Run-off
Segment Reporting Information [Line Items]
Gross, premiums written	$ 5,191	(25,069)	(8,910)
Operating Segments | Atrium
Segment Reporting Information [Line Items]
Gross, premiums written	206,656	192,373	171,494
Operating Segments | StarStone
Segment Reporting Information [Line Items]
Gross, premiums written	326,695	472,815	622,570
Operating Segments | United States | Non-life Run-off
Segment Reporting Information [Line Items]
Gross, premiums written	4,969
Operating Segments | United States | Atrium
Segment Reporting Information [Line Items]
Gross, premiums written	103,411
Operating Segments | United States | StarStone
Segment Reporting Information [Line Items]
Gross, premiums written	61,104
Operating Segments | United Kingdom | Non-life Run-off
Segment Reporting Information [Line Items]
Gross, premiums written	(229)
Operating Segments | United Kingdom | Atrium
Segment Reporting Information [Line Items]
Gross, premiums written	14,054
Operating Segments | United Kingdom | StarStone
Segment Reporting Information [Line Items]
Gross, premiums written	105,057
Operating Segments | Europe | Non-life Run-off
Segment Reporting Information [Line Items]
Gross, premiums written	1,615
Operating Segments | Europe | Atrium
Segment Reporting Information [Line Items]
Gross, premiums written	19,705
Operating Segments | Europe | StarStone
Segment Reporting Information [Line Items]
Gross, premiums written	62,181
Operating Segments | Asia | Non-life Run-off
Segment Reporting Information [Line Items]
Gross, premiums written	0
Operating Segments | Asia | Atrium
Segment Reporting Information [Line Items]
Gross, premiums written	7,834
Operating Segments | Asia | StarStone
Segment Reporting Information [Line Items]
Gross, premiums written	60,262
Operating Segments | Rest of World | Non-life Run-off
Segment Reporting Information [Line Items]
Gross, premiums written	(1,164)
Operating Segments | Rest of World | Atrium
Segment Reporting Information [Line Items]
Gross, premiums written	61,652
Operating Segments | Rest of World | StarStone
Segment Reporting Information [Line Items]
Gross, premiums written	$ 38,091
Operating Segments | Geographic concentration risk | Gross premiums written | Non-life Run-off
Segment Reporting Information [Line Items]
Gross premiums written (percent)	100.00%
Operating Segments | Geographic concentration risk | Gross premiums written | Atrium
Segment Reporting Information [Line Items]
Gross premiums written (percent)	100.00%
Operating Segments | Geographic concentration risk | Gross premiums written | StarStone
Segment Reporting Information [Line Items]
Gross premiums written (percent)	100.00%
Operating Segments | Geographic concentration risk | Gross premiums written | United States | Non-life Run-off
Segment Reporting Information [Line Items]
Gross premiums written (percent)	95.70%
Operating Segments | Geographic concentration risk | Gross premiums written | United States | Atrium
Segment Reporting Information [Line Items]
Gross premiums written (percent)	50.10%
Operating Segments | Geographic concentration risk | Gross premiums written | United States | StarStone
Segment Reporting Information [Line Items]
Gross premiums written (percent)	18.70%
Operating Segments | Geographic concentration risk | Gross premiums written | United Kingdom | Non-life Run-off
Segment Reporting Information [Line Items]
Gross premiums written (percent)	(4.40%)
Operating Segments | Geographic concentration risk | Gross premiums written | United Kingdom | Atrium
Segment Reporting Information [Line Items]
Gross premiums written (percent)	6.80%
Operating Segments | Geographic concentration risk | Gross premiums written | United Kingdom | StarStone
Segment Reporting Information [Line Items]
Gross premiums written (percent)	32.20%
Operating Segments | Geographic concentration risk | Gross premiums written | Europe | Non-life Run-off
Segment Reporting Information [Line Items]
Gross premiums written (percent)	31.10%
Operating Segments | Geographic concentration risk | Gross premiums written | Europe | Atrium
Segment Reporting Information [Line Items]
Gross premiums written (percent)	9.50%
Operating Segments | Geographic concentration risk | Gross premiums written | Europe | StarStone
Segment Reporting Information [Line Items]
Gross premiums written (percent)	19.00%
Operating Segments | Geographic concentration risk | Gross premiums written | Asia | Non-life Run-off
Segment Reporting Information [Line Items]
Gross premiums written (percent)	0.00%
Operating Segments | Geographic concentration risk | Gross premiums written | Asia | Atrium
Segment Reporting Information [Line Items]
Gross premiums written (percent)	3.80%
Operating Segments | Geographic concentration risk | Gross premiums written | Asia | StarStone
Segment Reporting Information [Line Items]
Gross premiums written (percent)	18.40%
Operating Segments | Geographic concentration risk | Gross premiums written | Rest of World | Non-life Run-off
Segment Reporting Information [Line Items]
Gross premiums written (percent)	(22.40%)
Operating Segments | Geographic concentration risk | Gross premiums written | Rest of World | Atrium
Segment Reporting Information [Line Items]
Gross premiums written (percent)	29.80%
Operating Segments | Geographic concentration risk | Gross premiums written | Rest of World | StarStone
Segment Reporting Information [Line Items]
Gross premiums written (percent)	11.70%
Other
Segment Reporting Information [Line Items]
Gross, premiums written	$ 13,441	$ 18,534	$ 32,378
Other | United States
Segment Reporting Information [Line Items]
Gross, premiums written	13,441
Other | United Kingdom
Segment Reporting Information [Line Items]
Gross, premiums written	0
Other | Europe
Segment Reporting Information [Line Items]
Gross, premiums written	0
Other | Asia
Segment Reporting Information [Line Items]
Gross, premiums written	0
Other | Rest of World
Segment Reporting Information [Line Items]
Gross, premiums written	$ 0
Other | Geographic concentration risk | Gross premiums written
Segment Reporting Information [Line Items]
Gross premiums written (percent)	100.00%
Other | Geographic concentration risk | Gross premiums written | United States
Segment Reporting Information [Line Items]
Gross premiums written (percent)	100.00%
Other | Geographic concentration risk | Gross premiums written | United Kingdom
Segment Reporting Information [Line Items]
Gross premiums written (percent)	0.00%
Other | Geographic concentration risk | Gross premiums written | Europe
Segment Reporting Information [Line Items]
Gross premiums written (percent)	0.00%
Other | Geographic concentration risk | Gross premiums written | Asia
Segment Reporting Information [Line Items]
Gross premiums written (percent)	0.00%
Other | Geographic concentration risk | Gross premiums written | Rest of World
Segment Reporting Information [Line Items]
Gross premiums written (percent)	0.00%

Segment Information - Summary_2

Segment Information - Summary of Company's Assets by Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 21,647,284	$ 19,826,099
Assets held-for-sale (Note 5)	711,278	1,474,770
Non-life Run-off | Held-for-sale or disposed of by sale, not discontinued operations | Arden
Segment Reporting, Asset Reconciling Item [Line Items]
Assets held-for-sale (Note 5)	95,500
Operating Segments | Non-life Run-off
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	19,062,400	15,775,409
Operating Segments | Atrium
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	615,778	580,405
Operating Segments | StarStone
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	2,583,247	3,985,137
Other
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ (614,141)	$ (514,852)

Unaudited Condensed Quarterly_3

Unaudited Condensed Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
INCOME
Net premiums earned	$ 108,146	$ 161,724	$ 142,871	$ 159,351	$ 185,336	$ 175,802	$ 190,962	$ 251,947	$ 572,092	$ 804,047	$ 695,779
Fees and commission income	14,121	10,787	10,010	7,528	9,522	6,437	6,017	6,477	42,446	28,453	35,088
Net investment income	61,530	72,130	94,443	74,714	76,847	81,502	74,271	75,651	302,817	308,271	261,698
Net realized and unrealized gains	803,467	500,005	967,608	(629,061)	153,477	145,060	260,669	452,760	1,642,019	1,011,966	(407,532)
Other income (losses)	33,372	48,404	(1,087)	20,443	21,703	822	8,831	5,714	101,132	37,070	34,073
Total income	1,020,636	793,050	1,213,845	(367,025)	446,885	409,623	540,750	792,549	2,660,506	2,189,807	619,106
EXPENSES
Net incurred losses and loss adjustment expenses	76,248	109,686	186,692	43,300	48,068	163,258	146,554	256,299	415,926	614,179	323,722
Acquisition costs	38,202	37,708	49,067	46,043	78,417	33,310	51,081	77,801	171,020	240,609	177,855
General and administrative expenses	142,394	115,828	144,830	98,427	116,780	97,365	100,676	98,263	501,479	413,084	348,786
Interest expense	16,872	15,003	14,018	13,415	13,519	14,950	13,036	11,036	59,308	52,541	25,696
Net foreign exchange (gains) losses	15,018	8,156	5,158	(11,939)	12,186	(13,665)	(2,579)	(3,854)	16,393	(7,912)	2,644
Total expenses	288,734	286,381	399,765	189,246	268,970	295,218	308,768	439,545	1,164,126	1,312,501	878,703
EARNINGS (LOSS) BEFORE INCOME TAXES	731,902	506,669	814,080	(556,271)	177,915	114,405	231,982	353,004	1,496,380	877,306	(259,597)
Income tax benefit (expense)	1,468	(13,915)	(16,652)	5,272	12,893	(13,465)	(7,698)	(4,102)	(23,827)	(12,372)	3,689
Earnings (losses) from equity method investments	85,844	149,065	(8,790)	12,450	11,722	17,703	17,713	8,772	238,569	55,910	42,147
NET EARNINGS (LOSS) FROM CONTINUING OPERATIONS	819,214	641,819	788,638	(538,549)	202,530	118,643	241,997	357,674	1,711,122	920,844	(213,761)
Net earnings from discontinued operations, net of income taxes	15,441	4,031	(1,152)	(2,069)	(4,666)	7,916	(3,943)	8,068	16,251	7,375	1,489
NET EARNINGS (LOSS)	834,655	645,850	787,486	(540,618)	197,864	126,559	238,054	365,742	1,727,373	928,219	(212,272)
Net loss attributable to noncontrolling interest	(3,131)	(21,912)	19,992	32,722	4,900	109	2,713	2,148	27,671	9,870	62,051
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	831,524	623,938	807,478	(507,896)	202,764	126,668	240,767	367,890	1,755,044	938,089	(150,221)
Dividends on preferred shares	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(9,139)	(35,700)	(35,914)	(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$ 822,599	$ 615,013	$ 798,553	$ (516,821)	$ 193,839	$ 117,743	$ 231,842	$ 358,751	$ 1,719,344	$ 902,175	$ (162,354)
Basic:
Net earnings (loss) from continuing operations (dollars per share)	$ 37.91	$ 28.39	$ 37.06	$ (23.93)	$ 9.15	$ 5.26	$ 10.90	$ 16.49	$ 79.43	$ 41.80	$ (7.89)
Net earnings (loss) from discontinued operations (dollars per share)	0.33	0.11	(0.03)	(0.05)	(0.13)	0.22	(0.11)	0.22	0.35	0.20	0.05
Net earnings (loss) per ordinary share (dollars per share)	38.24	28.50	37.03	(23.98)	9.02	5.48	10.79	16.71	79.78	42	(7.84)
Diluted:
Net earnings (loss) from continuing operations (dollars per share)	37.47	28.13	36.68	(23.93)	9.02	5.21	10.81	16.35	78.45	41.23	(7.89)
Net earnings (loss) from discontinued operations (dollars per share)	0.32	0.11	(0.03)	(0.05)	(0.13)	0.21	(0.11)	0.22	0.35	0.20	0.05
Net earnings (loss) per ordinary share (dollars per share)	$ 37.79	$ 28.24	$ 36.65	$ (23.98)	$ 8.89	$ 5.42	$ 10.70	$ 16.57	$ 78.80	$ 41.43	$ (7.84)

Schedule I - Summary of Inves_2

Schedule I - Summary of Investments Other Than Investments in Related Parties (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	$ 10,168,005
Fair Value	10,796,331
Amount at which shown in the balance sheet	10,796,331
Equity investments	846,795	$ 726,721
Fair value of other investments in funds or companies owned by or affiliated with related parties	4,244,034	2,518,031
Stone Point
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Fixed maturity investments	18,200
Affiliated entity
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Fair value of other investments in funds or companies owned by or affiliated with related parties	3,300,000
Affiliated entity | Trident
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Equity investments	77,100
AmTrust
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Indirect investment	230,300	$ 240,100
Equities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	444,570
Fair Value	512,557
Amount at which shown in the balance sheet	512,557
Other investments, at fair value
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	982,770
Fair Value	982,770
Amount at which shown in the balance sheet	982,770
Funds Held - Directly Managed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	5,168,869
Fair Value	5,646,955
Amount at which shown in the balance sheet	5,646,955
Funds Held - Directly Managed | U.S. government and agency
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	219,487
Fair Value	233,050
Amount at which shown in the balance sheet	233,050
Funds Held - Directly Managed | U.K. government
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	34,494
Fair Value	37,508
Amount at which shown in the balance sheet	37,508
Funds Held - Directly Managed | Other government
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	321,306
Fair Value	352,026
Amount at which shown in the balance sheet	352,026
Funds Held - Directly Managed | Corporate
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	3,353,054
Fair Value	3,749,383
Amount at which shown in the balance sheet	3,749,383
Funds Held - Directly Managed | Municipal
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	116,588
Fair Value	132,637
Amount at which shown in the balance sheet	132,637
Funds Held - Directly Managed | Residential mortgage-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	219,360
Fair Value	225,074
Amount at which shown in the balance sheet	225,074
Funds Held - Directly Managed | Commercial mortgage-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	554,639
Fair Value	577,602
Amount at which shown in the balance sheet	577,602
Funds Held - Directly Managed | Asset-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	349,941
Fair Value	339,675
Amount at which shown in the balance sheet	339,675
Available-for-sale securities
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	3,571,796
Fair Value	3,654,049
Amount at which shown in the balance sheet	3,654,049
Available-for-sale securities | U.S. government and agency
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	715,527
Fair Value	717,998
Amount at which shown in the balance sheet	717,998
Available-for-sale securities | U.K. government
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	12,494
Fair Value	13,574
Amount at which shown in the balance sheet	13,574
Available-for-sale securities | Other government
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	142,459
Fair Value	150,127
Amount at which shown in the balance sheet	150,127
Available-for-sale securities | Corporate
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	1,873,184
Fair Value	1,937,349
Amount at which shown in the balance sheet	1,937,349
Available-for-sale securities | Municipal
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	28,881
Fair Value	30,032
Amount at which shown in the balance sheet	30,032
Available-for-sale securities | Residential mortgage-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	326,268
Fair Value	328,871
Amount at which shown in the balance sheet	328,871
Available-for-sale securities | Commercial mortgage-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	273,516
Fair Value	276,488
Amount at which shown in the balance sheet	276,488
Available-for-sale securities | Asset-backed
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Cost	199,467
Fair Value	199,610
Amount at which shown in the balance sheet	199,610
Mitchell International | Affiliated entity
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Fair value of other investments in funds or companies owned by or affiliated with related parties	$ 26,900		$ 25,000

Schedule II - Condensed Balance

Schedule II - Condensed Balance Sheets (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
ASSETS
Cash and cash equivalents	$ 901,152	$ 624,472	$ 535,809
Other assets	925,533	1,162,955
TOTAL ASSETS	21,647,284	19,826,099
LIABILITIES
Debt obligations (Note 15)	1,373,259	1,191,207
Other liabilities	942,905	994,584
TOTAL LIABILITIES	14,593,844	14,530,957
SHAREHOLDERS’ EQUITY (Note 17)
Treasury shares, at cost (Series C Preferred Shares 2020 and 2019: 388,571)	(421,559)	(421,559)
Joint Share Ownership Plan (voting ordinary shares, held in trust 2020: 565,630; 2019: 0)	(566)	0
Additional paid-in capital	1,836,074	1,836,778
Accumulated other comprehensive income	80,659	7,171
Retained earnings	4,647,312	2,887,892
Total Enstar Shareholders’ Equity	6,674,395	4,842,183
TOTAL LIABILITIES, REDEEMABLE NONCONTROLLING INTEREST AND SHAREHOLDERS’ EQUITY	$ 21,647,284	$ 19,826,099
Parenthetical Disclosures [Abstract]
Common shares, par value (dollars per share)	$ 1	$ 1
Ordinary shares, shares issued (shares)	22,085,232	21,511,505
Ordinary shares, outstanding (shares)	22,085,232	21,511,505
Treasury stock, preferred shares (shares)	388,571	388,571
Treasury stock, ordinary shares (shares)	565,630	0
Voting ordinary shares
SHAREHOLDERS’ EQUITY (Note 17)
Ordinary shares	$ 18,576	$ 18,002
Parenthetical Disclosures [Abstract]
Common shares, par value (dollars per share)	$ 1	$ 1
Ordinary shares, shares issued (shares)	18,575,550	18,001,823
Ordinary shares, outstanding (shares)	18,575,550	18,001,823
Series C non-voting convertible ordinary shares
SHAREHOLDERS’ EQUITY (Note 17)
Ordinary shares	$ 2,600	$ 2,600
Parenthetical Disclosures [Abstract]
Ordinary shares, shares issued (shares)	2,599,672	2,599,672
Ordinary shares, outstanding (shares)	2,599,672	2,599,672
Series E non-voting convertible ordinary shares
SHAREHOLDERS’ EQUITY (Note 17)
Ordinary shares	$ 910	$ 910
Parenthetical Disclosures [Abstract]
Ordinary shares, shares issued (shares)	910,010	910,010
Ordinary shares, outstanding (shares)	910,010	910,010
Series C Preferred Shares
SHAREHOLDERS’ EQUITY (Note 17)
Preferred shares	$ 389	$ 389
Parenthetical Disclosures [Abstract]
Preferred shares, issued (shares)	388,571	388,571
Treasury stock, preferred shares (shares)	388,571	388,571
Series D Preferred Shares
SHAREHOLDERS’ EQUITY (Note 17)
Preferred shares	$ 400,000	$ 400,000
Parenthetical Disclosures [Abstract]
Preferred shares, issued (shares)	16,000	16,000
Preferred shares, outstanding (shares)	16,000	16,000
Series E Preferred Shares
SHAREHOLDERS’ EQUITY (Note 17)
Preferred shares	$ 110,000	$ 110,000
Parenthetical Disclosures [Abstract]
Preferred shares, issued (shares)	4,400	4,400
Preferred shares, outstanding (shares)	4,400	4,400
Enstar Group Limited
ASSETS
Cash and cash equivalents	$ 7,872	$ 4,568
Balances due from subsidiaries	18,951	134,897
Investments in subsidiaries	7,887,255	6,050,197
Other assets	8,047	6,391
TOTAL ASSETS	7,922,125	6,196,053
LIABILITIES
Debt obligations (Note 15)	903,447	1,191,207
Balances due to subsidiaries	300,987	135,532
Other liabilities	43,296	27,131
TOTAL LIABILITIES	1,247,730	1,353,870
SHAREHOLDERS’ EQUITY (Note 17)
Treasury shares, at cost (Series C Preferred Shares 2020 and 2019: 388,571)	(421,559)	(421,559)
Additional paid-in capital	1,836,074	1,836,778
Accumulated other comprehensive income	80,659	7,171
Retained earnings	4,647,312	2,887,892
Total Enstar Shareholders’ Equity	6,674,395	4,842,183
TOTAL LIABILITIES, REDEEMABLE NONCONTROLLING INTEREST AND SHAREHOLDERS’ EQUITY	7,922,125	6,196,053
Enstar Group Limited | Voting ordinary shares
SHAREHOLDERS’ EQUITY (Note 17)
Ordinary shares	18,576	18,002
Enstar Group Limited | Series C non-voting convertible ordinary shares
SHAREHOLDERS’ EQUITY (Note 17)
Ordinary shares	2,600	2,600
Enstar Group Limited | Series E non-voting convertible ordinary shares
SHAREHOLDERS’ EQUITY (Note 17)
Ordinary shares	910	910
Enstar Group Limited | Series C Preferred Shares
SHAREHOLDERS’ EQUITY (Note 17)
Preferred shares	389	389
Enstar Group Limited | Series D Preferred Shares
SHAREHOLDERS’ EQUITY (Note 17)
Preferred shares	400,000	400,000
Enstar Group Limited | Series E Preferred Shares
SHAREHOLDERS’ EQUITY (Note 17)
Preferred shares	$ 110,000	$ 110,000

Schedule II - Condensed Stateme

Schedule II - Condensed Statements of Earnings (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
INCOME
Net investment income	$ 61,530	$ 72,130	$ 94,443	$ 74,714	$ 76,847	$ 81,502	$ 74,271	$ 75,651	$ 302,817	$ 308,271	$ 261,698
Total income	1,020,636	793,050	1,213,845	(367,025)	446,885	409,623	540,750	792,549	2,660,506	2,189,807	619,106
EXPENSES
General and administrative expenses	142,394	115,828	144,830	98,427	116,780	97,365	100,676	98,263	501,479	413,084	348,786
Interest expense	16,872	15,003	14,018	13,415	13,519	14,950	13,036	11,036	59,308	52,541	25,696
Net foreign exchange losses (gains)	15,018	8,156	5,158	(11,939)	12,186	(13,665)	(2,579)	(3,854)	16,393	(7,912)	2,644
Total expenses	288,734	286,381	399,765	189,246	268,970	295,218	308,768	439,545	1,164,126	1,312,501	878,703
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR	831,524	623,938	807,478	(507,896)	202,764	126,668	240,767	367,890	1,755,044	938,089	(150,221)
Dividends on preferred shares	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(8,925)	(9,139)	(35,700)	(35,914)	(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS	$ 822,599	$ 615,013	$ 798,553	$ (516,821)	$ 193,839	$ 117,743	$ 231,842	$ 358,751	1,719,344	902,175	(162,354)
Enstar Group Limited
INCOME
Net investment income									1,680	3,649	142
Total income									1,680	3,649	142
EXPENSES
General and administrative expenses									45,689	44,964	68,977
Interest expense									51,739	51,508	27,353
Net foreign exchange losses (gains)									(2,655)	(21,516)	7,655
Total expenses									94,773	74,956	103,985
EARNINGS (LOSSES) BEFORE EQUITY IN UNDISTRIBUTED EARNINGS OF SUBSIDIARIES									(93,093)	(71,307)	(103,843)
Equity in undistributed earnings (losses) of subsidiaries - continuing operations									1,831,886	1,002,021	(47,867)
Equity in undistributed earnings (losses) of subsidiaries - discontinued operations									16,251	7,375	1,489
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR									1,755,044	938,089	(150,221)
Dividends on preferred shares									(35,700)	(35,914)	(12,133)
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR ORDINARY SHAREHOLDERS									$ 1,719,344	$ 902,175	$ (162,354)

Schedule II - Comprehensive Inc

Schedule II - Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Statement of Income Captions [Line Items]
NET EARNINGS	$ 831,524	$ 623,938	$ 807,478	$ (507,896)	$ 202,764	$ 126,668	$ 240,767	$ 367,890	$ 1,755,044	$ 938,089	$ (150,221)
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSTAR									1,828,532	934,820	(150,248)
Enstar Group Limited
Condensed Statement of Income Captions [Line Items]
NET EARNINGS									1,755,044	938,089	(150,221)
OTHER COMPREHENSIVE INCOME (LOSS) RELATING TO SUBSIDIARIES, NET OF TAX									73,488	(3,269)	(27)
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSTAR									$ 1,828,532	$ 934,820	$ (150,248)

Schedule II - Condensed State_2

Schedule II - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	10 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
FINANCING ACTIVITIES:
Net proceeds from the issuance of preferred shares		$ 0	$ 0	$ 495,357
Dividends on preferred shares		(35,700)	(35,914)	(12,133)
Repurchase of shares	$ (26,000)	(26,006)	0	0
Repayment of loans		(679,000)	(742,574)	(914,319)
Receipt of loans		858,512	1,070,502	1,132,507
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH		540,540	73,193	(230,252)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF YEAR		971,349	901,996	1,166,116
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, END OF YEAR	1,373,116	1,373,116	971,349	901,996
Enstar Group Limited
OPERATING ACTIVITIES:
Net cash flows provided by (used in) operating activities		117,220	(128,462)	(128,382)
INVESTING ACTIVITIES:
Dividends and return of capital from subsidiaries		44,000	65,500	101,000
Contributions to subsidiaries		(26,000)	(240,382)	(660,339)
Net cash flows used in investing activities		18,000	(174,882)	(559,339)
FINANCING ACTIVITIES:
Net proceeds from the issuance of preferred shares		0	0	495,357
Dividends on preferred shares		(35,700)	(35,914)	(12,133)
Repurchase of shares		(26,006)	0	0
Repayment of loans		(449,210)	(219,000)	(898,633)
Receipt of loans		379,000	547,613	1,115,885
Net cash flows provided by financing activities		(131,916)	292,699	700,476
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH		3,304	(10,645)	12,755
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF YEAR		4,568	15,213	2,458
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, END OF YEAR	$ 7,872	$ 7,872	$ 4,568	$ 15,213

Schedule II - Narrative (Detail

Schedule II - Narrative (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Aug. 26, 2020
Condensed Financial Statements, Captions [Line Items]
Dividends and return of capital from subsidiaries, non-cash									$ 130,000,000	$ 0	$ 0
Contributions to subsidiaries, non-cash									0	0	414,800,000
Retained earnings	$ 4,647,312,000				$ 2,887,892,000				4,647,312,000	2,887,892,000
Net earnings attributable to Enstar Group Limited	822,599,000	$ 615,013,000	$ 798,553,000	$ (516,821,000)	193,839,000	$ 117,743,000	$ 231,842,000	$ 358,751,000	1,719,344,000	902,175,000	(162,354,000)
Limited Parental Guarantee
Condensed Financial Statements, Captions [Line Items]
Total parental guarantees	1,500,000,000				1,000,000,000				1,500,000,000	1,000,000,000
Enstar Group Limited
Condensed Financial Statements, Captions [Line Items]
Interest paid									46,500,000	46,500,000	25,100,000
Retained earnings	4,647,312,000				2,887,892,000				4,647,312,000	2,887,892,000
Increase in retained earnings									1,759,400,000
Net earnings attributable to Enstar Group Limited									1,719,344,000	902,175,000	$ (162,354,000)
Enstar Group Limited | Limited Parental Guarantee
Condensed Financial Statements, Captions [Line Items]
Total parental guarantees	1,500,000,000				1,000,000,000				1,500,000,000	1,000,000,000
5.75% Junior Subordinated Notes due 2040 | Junior Subordinated Notes
Condensed Financial Statements, Captions [Line Items]
Aggregate principal amount												$ 350,000,000
Letters of Credit | FAL Facility | Loan facilities
Condensed Financial Statements, Captions [Line Items]
Available unutilized capacity	$ 210,000,000				$ 252,000,000				$ 210,000,000	$ 252,000,000

Schedule III - Supplementary _2

Schedule III - Supplementary Insurance Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Acquisition Costs	$ 44,439	$ 116,513	$ 87,258
Reserves for Losses and Loss Adjustment Expenses	10,593,282	9,868,404	9,048,796
Unearned Premiums	274,681	533,692	606,059
Policy Benefits for Life and Annuity Contracts	0	0	105,080
Net Premiums Earned	572,092	804,047	695,779
Net Investment Income	302,817	308,271	261,698
Losses and Loss Expenses and Policy Benefits	415,926	614,179	323,722
Amortization of Deferred Acquisition Costs	171,020	240,609	177,855
Other Operating Expenses	501,479	413,084	348,786
Net Premiums Written	432,824	545,053	654,347
Held-for-sale or disposed of by sale, not discontinued operations | Northshore
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred acquisition costs	24,000
Losses and loss adjustment expenses	254,149
Unearned premiums	91,400
Operating Segments | Non-life Run-off
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Acquisition Costs	22,736	41,753	4,378
Reserves for Losses and Loss Adjustment Expenses	9,235,082	8,295,361	7,540,662
Unearned Premiums	71,629	129,715	136,023
Policy Benefits for Life and Annuity Contracts	0	0	0
Net Premiums Earned	58,695	168,496	9,427
Net Investment Income	282,048	275,236	226,287
Losses and Loss Expenses and Policy Benefits	44,995	51,625	(306,067)
Amortization of Deferred Acquisition Costs	20,177	73,642	4,006
Other Operating Expenses	298,717	270,445	197,824
Net Premiums Written	2,987	(25,338)	(9,217)
Operating Segments | Atrium
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Acquisition Costs	0	22,184	20,355
Reserves for Losses and Loss Adjustment Expenses	0	231,672	241,284
Unearned Premiums	0	80,863	70,429
Policy Benefits for Life and Annuity Contracts	0	0	0
Net Premiums Earned	175,393	164,059	146,315
Net Investment Income	5,542	7,049	5,686
Losses and Loss Expenses and Policy Benefits	87,226	77,276	69,810
Amortization of Deferred Acquisition Costs	59,611	56,956	50,646
Other Operating Expenses	34,600	28,277	24,698
Net Premiums Written	183,194	172,356	153,488
Operating Segments | StarStone
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Acquisition Costs	21,439	52,188	62,161
Reserves for Losses and Loss Adjustment Expenses	1,327,956	1,318,294	1,247,989
Unearned Premiums	191,502	305,116	382,605
Policy Benefits for Life and Annuity Contracts	0	0	0
Net Premiums Earned	318,115	451,112	515,163
Net Investment Income	27,443	34,396	27,000
Losses and Loss Expenses and Policy Benefits	266,738	469,240	543,080
Amortization of Deferred Acquisition Costs	90,797	109,369	120,517
Other Operating Expenses	123,864	68,417	98,137
Net Premiums Written	233,202	379,523	478,009
Other
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Acquisition Costs	264	388	364
Reserves for Losses and Loss Adjustment Expenses	30,244	23,077	18,861
Unearned Premiums	11,550	17,998	17,002
Policy Benefits for Life and Annuity Contracts	0	0	105,080
Net Premiums Earned	19,889	20,380	24,874
Net Investment Income	(12,216)	(8,410)	2,725
Losses and Loss Expenses and Policy Benefits	16,967	16,038	16,899
Amortization of Deferred Acquisition Costs	435	642	2,686
Other Operating Expenses	44,298	45,945	28,127
Net Premiums Written	$ 13,441	$ 18,512	$ 32,067

Schedule IV - Reinsurance (Deta

Schedule IV - Reinsurance (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Life insurance in force, gross					$ 725,293					$ 725,293	$ 855,366
Life insurance in force, ceded					(65,795)					(65,795)	(84,603)
Life insurance in force, assumed					0					0	0
Life insurance in force, net					$ 659,498					$ 659,498	$ 770,763
Life insurance in force, percentage of amount assumed to net					0.00%					0.00%	0.00%
Premiums earned, gross									$ 542,119	$ 680,507	$ 543,061
Ceded premium earned									(157,826)	(145,483)	(166,334)
Premiums earned, assumed									187,799	269,023	319,052
Net, premiums earned	$ 108,146	$ 161,724	$ 142,871	$ 159,351	$ 185,336	$ 175,802	$ 190,962	$ 251,947	572,092	804,047	695,779
Property and casualty
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Premiums earned, gross									542,119	679,212	539,169
Ceded premium earned									(157,826)	(145,460)	(166,308)
Premiums earned, assumed									187,799	269,023	319,052
Net, premiums earned									$ 572,092	$ 802,775	$ 691,913
Premiums earned, percentage of amount assumed to net									32.80%	33.50%	46.10%
Life and annuities
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Premiums earned, gross										$ 1,295	$ 3,892
Ceded premium earned										(23)	(26)
Premiums earned, assumed										0	0
Net, premiums earned										$ 1,272	$ 3,866
Premiums earned, percentage of amount assumed to net										0.00%	0.00%

Schedule V - Valuation and Qu_2

Schedule V - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2017
Cumulative effect of change in accounting principle
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Financial instruments, allowance for credit loss				$ 3,000
Allowance for estimated uncollectible reinsurance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 137,122	$ 147,639	$ 156,732	147,639	$ 165,213
Charged to costs and expenses	0	0	0
Charged to other	124	111	(1,837)
Deductions	(10,641)	(9,204)	(6,644)
Balance at End of Year	137,122	147,639	156,732
Insurance balances recoverable, allowance for estimated uncollectible insurance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	4,824	3,818	0	3,818
Charged to costs and expenses	0	0
Charged to other	1,006	3,818
Deductions	0	0
Balance at End of Year	4,824	3,818	0
Valuation allowance for deferred tax assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	118,229	117,390	212,113	$ 117,390	$ 188,300
Charged to costs and expenses	3,854	2,792	(2,492)
Charged to other	0	0	18,000
Deductions	(3,015)	(97,515)	8,305
Balance at End of Year	$ 118,229	$ 117,390	$ 212,113

Schedule VI - Supplementary I_2

Schedule VI - Supplementary Information Concerning Property/Casualty Insurance Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Abstract]
Deferred Acquisition Costs	$ 44,439	$ 116,513	$ 87,258
Reserves for Unpaid Losses and Loss Adjustment Expenses	10,593,282	9,868,404	9,048,796
Unearned Premiums	274,681	533,692	606,059
Net Premiums Earned	572,092	802,775	691,912
Net Investment Income	302,817	307,775	260,120
Net Losses and Loss Expenses Incurred - Current Year	405,178	580,074	533,081
Net Loses and Loss Expenses Incurred - Prior Year	10,748	34,105	(209,359)
Net Paid Losses and Loss Expenses	(1,485,489)	(1,788,470)	(1,334,786)
Amortization of Deferred Acquisition Costs	171,020	240,432	177,855
Net Premiums Written	$ 432,824	$ 543,781	$ 650,484