Arch Capital (ACGL) 10-Q 8 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 01, 2019
Document and Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-16209
Entity Registrant Name	ARCH CAPITAL GROUP LTD.
Entity Incorporation, State or Country Code	D0
Entity Tax Identification Number	98-0374481
Entity Address, Address Line One	Waterloo House, Ground Floor
Entity Address, Address Line Two	100 Pitts Bay Road,
Entity Address, City or Town	Pembroke
Entity Address, Postal Zip Code	HM 08,
Entity Address, Country	BM
City Area Code	(441)
Local Phone Number	278-9250
Entity Listings [Line Items]
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
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		405,308,162
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2019
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0000947484
Amendment Flag	false
Common shares
Entity Listings [Line Items]
Title of 12(b) Security	Common shares, $0.0011 par value per share
Trading Symbol	ACGL
Security Exchange Name	NASDAQ
Depositary Series E Preferred Stock
Entity Listings [Line Items]
Title of 12(b) Security	Depositary shares, each representing a 1/100th interest in a 5.25% Series E preferred share
Trading Symbol	ACGLP
Security Exchange Name	NASDAQ
Depositary Series F Preferred Stock
Entity Listings [Line Items]
Title of 12(b) Security	Depositary shares, each representing a 1/100th interest in a 5.45% Series F preferred share
Trading Symbol	ACGLO
Security Exchange Name	NASDAQ

Unaudited Consolidated Balance

Unaudited Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Investments:
Fixed maturities available for sale, at fair value (amortized cost: $16,146,333 and $14,829,902)	$ 16,470,523	$ 14,699,010
Short-term investments available for sale, at fair value (amortized cost: $752,207 and $956,238)	751,989	955,880
Collateral received under securities lending, at fair value (amortized cost: $430,255 and $274,125)	430,263	274,133
Equity securities, at fair value	550,485	338,899
Investments accounted for using the fair value option	3,838,243	3,983,571
Investments accounted for using the equity method	1,575,832	1,493,791
Total investments	23,617,335	21,745,284
Cash	880,099	646,556
Accrued investment income	116,196	114,641
Securities pledged under securities lending, at fair value (amortized cost: $419,297 and $266,786)	420,415	268,395
Premiums receivable	1,618,186	1,299,150
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	3,168,195	2,919,372
Contractholder receivables	2,094,683	2,079,111
Ceded unearned premiums	1,168,258	975,469
Deferred acquisition costs	622,028	569,574
Receivable for securities sold	50,615	36,246
Goodwill and intangible assets	624,500	634,920
Other assets	1,192,093	929,611
Total assets	35,572,603	32,218,329
Liabilities
Reserve for losses and loss adjustment expenses	12,389,384	11,853,297
Unearned premiums	4,243,372	3,753,636
Reinsurance balances payable	601,891	393,107
Contractholder payables	2,094,683	2,079,111
Collateral held for insured obligations	205,449	236,630
Senior notes	1,871,386	1,733,528
Revolving credit agreement borrowings	490,720	455,682
Securities lending payable	430,255	274,125
Payable for securities purchased	176,130	90,034
Other liabilities	1,007,524	911,500
Total liabilities	23,510,794	21,780,650
Commitments and Contingencies
Redeemable noncontrolling interests	48,789	206,292
Shareholders' Equity
Non-cumulative preferred shares	780,000	780,000
Common shares ($0.0011 par, shares issued: 574,173,205 and 570,737,283)	638	634
Additional paid-in capital	1,864,468	1,793,781
Retained earnings	10,705,025	9,426,299
Accumulated other comprehensive income (loss), net of deferred income tax	211,714	(178,720)
Common shares held in treasury, at cost (shares: 168,942,674 and 168,282,449)	(2,403,749)	(2,382,167)
Total shareholders' equity available to Arch	11,158,096	9,439,827
Non-redeemable noncontrolling interests	854,924	791,560
Total shareholders' equity	12,013,020	10,231,387
Total liabilities, noncontrolling interests and shareholders' equity	$ 35,572,603	$ 32,218,329

Unaudited Consolidated Balanc_2

Unaudited Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fixed maturities available for sale, at amortized cost	$ 16,146,333	$ 14,829,902
Short-term investments available for sale, at amortized cost	752,207	956,238
Collateral received under securities lending, at amortized cost	430,255	274,125
Securities pledged under securities lending, at amortized cost	$ 419,297	$ 266,786
Common shares, par value per share	$ 0.0011	$ 0.0011
Common shares issued (shares)	574,173,205	570,737,283
Common shares held in treasury (shares)	168,942,674	168,282,449

Unaudited Consolidated Statemen

Unaudited Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues
Net premiums written	$ 1,613,457	$ 1,333,553	$ 4,583,614	$ 4,044,993
Change in unearned premiums	(175,434)	(42,675)	(312,998)	(182,453)
Net premiums earned	1,438,023	1,290,878	4,270,616	3,862,540
Net investment income	161,488	144,024	473,475	406,416
Net realized gains (losses)	62,518	(51,705)	324,889	(239,314)
Other-than-temporary impairment losses	(1,163)	(492)	(2,521)	(1,124)
Less investment impairments recognized in other comprehensive income, before taxes	0	0	0	0
Net impairment losses recognized in earnings	(1,163)	(492)	(2,521)	(1,124)
Other underwriting income	3,326	5,823	18,104	15,046
Equity in net income of investment funds accounted for using the equity method	17,130	15,982	96,533	52,523
Other income	1,338	(726)	3,550	2,461
Total revenues	1,682,660	1,403,784	5,184,646	4,098,548
Expenses
Losses and loss adjustment expenses	802,455	699,420	2,288,530	2,062,433
Acquisition expenses	211,120	201,602	619,057	595,816
Other operating expenses	196,512	161,098	596,589	512,294
Corporate expenses	17,061	14,335	53,274	52,159
Amortization of intangible assets	20,003	26,315	60,214	79,523
Interest expense	31,328	29,730	89,673	90,710
Net foreign exchange (gains) losses	(33,124)	(10,838)	(31,697)	(44,823)
Total expenses	1,245,355	1,121,662	3,675,640	3,348,112
Income before income taxes	437,305	282,122	1,509,006	750,436
Income tax expense	(38,116)	(33,356)	(128,474)	(78,939)
Net income	399,189	248,766	1,380,532	671,497
Net (income) loss attributable to noncontrolling interests	(6,736)	(21,358)	(70,597)	(50,020)
Net income available to Arch	392,453	227,408	1,309,935	621,477
Preferred dividends	(10,403)	(10,402)	(31,209)	(31,242)
Loss on redemption of preferred shares	0	0	0	(2,710)
Net income available to Arch common shareholders	$ 382,050	$ 217,006	$ 1,278,726	$ 587,525
Net income per common share and common share equivalent
Basic (per share)	$ 0.95	$ 0.54	$ 3.19	$ 1.45
Diluted (per share)	$ 0.92	$ 0.53	$ 3.11	$ 1.42
Weighted average common shares and common share equivalents outstanding
Basic (shares)	402,564,121	402,939,092	401,419,153	405,076,228
Diluted (shares)	413,180,201	411,721,214	410,807,402	413,993,192

Unaudited Consolidated Statem_2

Unaudited Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Comprehensive Income
Net income	$ 399,189	$ 248,766	$ 1,380,532	$ 671,497
Unrealized appreciation (decline) in value of available-for-sale investments:
Unrealized holding gains (losses) arising during period	59,290	(53,308)	507,650	(305,256)
Reclassification of net realized (gains) losses, net of income taxes, included in net income (loss)	(38,743)	23,203	(104,309)	122,307
Foreign currency translation adjustments	(16,424)	2,063	(6,641)	(9,250)
Comprehensive income	403,312	220,724	1,777,232	479,298
Net (income) loss attributable to noncontrolling interests	(6,736)	(21,358)	(70,597)	(50,020)
Other comprehensive (income) loss attributable to noncontrolling interests	764	1,158	(6,266)	2,908
Comprehensive income available to Arch	$ 397,340	$ 200,524	$ 1,700,369	$ 432,186

Unaudited Consolidated Statem_3

Unaudited Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Non-cumulative preferred shares	Common shares	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss), net of deferred income tax	Unrealized appreciation (decline) in value of available-for-sale securities, net of deferred income tax	Foreign currency translation adjustments	Common shares held in treasury, at cost	Convertible non-voting common equivalent preferred shares
Balance at beginning of period, as adjusted					$ 8,712,683		$ 7,606
Balance at beginning of period at Dec. 31, 2017		$ 872,555	$ 611	$ 1,230,617	8,562,889	$ 118,044	157,400	$ (39,356)	$ (2,077,741)	$ 489,627
Cumulative effect of an accounting change at Dec. 31, 2017					149,794		(149,794)
Preferred shares redeemed		(92,555)
Preferred shares converted to common shares				489,608						(489,627)
Common shares issued, net			22
Other changes				55,274
Net income	$ 671,497				671,497
Net (income) loss attributable to noncontrolling interests	(50,020)				(50,020)
Preferred share dividends	(31,242)				(31,242)
Loss on redemption of preferred shares	(2,710)				(2,710)
Unrealized holding gains (losses) during period, net of reclassification adjustment							(182,949)
Unrealized holding gains (losses) during period attributable to noncontrolling interests							3,123
Foreign currency translation adjustments	(9,250)							(9,250)
Foreign currency translation adjustments attributable to noncontrolling interests								(215)
Shares repurchased for treasury	(184,500)								(202,410)
Balance at end of period at Sep. 30, 2018	9,355,148	780,000	633	1,775,499	9,300,208	(221,041)	(172,220)	(48,821)	(2,280,151)	0
Non-redeemable noncontrolling interests, end of period at Sep. 30, 2018	876,754
Total shareholders’ equity at Sep. 30, 2018	10,231,902
Balance at beginning of period, as adjusted					9,083,202		(143,353)
Balance at beginning of period at Jun. 30, 2018		780,000	633	1,760,606	9,083,202	(194,157)	(143,353)	(50,804)	(2,266,529)	0
Cumulative effect of an accounting change at Jun. 30, 2018					0		0
Preferred shares redeemed		0
Preferred shares converted to common shares				0						0
Common shares issued, net			0
Other changes				14,893
Net income	248,766				248,766
Net (income) loss attributable to noncontrolling interests	(21,358)				(21,358)
Preferred share dividends	(10,402)				(10,402)
Loss on redemption of preferred shares	0				0
Unrealized holding gains (losses) during period, net of reclassification adjustment							(30,105)
Unrealized holding gains (losses) during period attributable to noncontrolling interests							1,238
Foreign currency translation adjustments	2,063							2,063
Foreign currency translation adjustments attributable to noncontrolling interests								(80)
Shares repurchased for treasury									(13,622)
Balance at end of period at Sep. 30, 2018	9,355,148	780,000	633	1,775,499	9,300,208	(221,041)	(172,220)	(48,821)	(2,280,151)	0
Non-redeemable noncontrolling interests, end of period at Sep. 30, 2018	876,754
Total shareholders’ equity at Sep. 30, 2018	10,231,902
Balance at beginning of period, as adjusted					9,426,299		(114,178)
Balance at beginning of period at Dec. 31, 2018	9,439,827	780,000	634	1,793,781	9,426,299	(178,720)	(114,178)	(64,542)	(2,382,167)	0
Cumulative effect of an accounting change at Dec. 31, 2018					0		0
Preferred shares redeemed		0
Preferred shares converted to common shares				0						0
Common shares issued, net			4
Other changes				70,687
Net income	1,380,532				1,380,532
Net (income) loss attributable to noncontrolling interests	(70,597)				(70,597)
Preferred share dividends	(31,209)				(31,209)
Loss on redemption of preferred shares	0				0
Unrealized holding gains (losses) during period, net of reclassification adjustment							403,341
Unrealized holding gains (losses) during period attributable to noncontrolling interests							(5,970)
Foreign currency translation adjustments	(6,641)							(6,641)
Foreign currency translation adjustments attributable to noncontrolling interests								(296)
Shares repurchased for treasury	(2,900)								(21,582)
Balance at end of period at Sep. 30, 2019	11,158,096	780,000	638	1,864,468	10,705,025	211,714	283,193	(71,479)	(2,403,749)	0
Non-redeemable noncontrolling interests, end of period at Sep. 30, 2019	854,924
Total shareholders’ equity at Sep. 30, 2019	12,013,020
Balance at beginning of period, as adjusted					10,322,975		261,627
Balance at beginning of period at Jun. 30, 2019		780,000	638	1,847,949	10,322,975	206,827	261,627	(54,800)	(2,401,037)	0
Cumulative effect of an accounting change at Jun. 30, 2019					0		0
Preferred shares redeemed		0
Preferred shares converted to common shares				0						0
Common shares issued, net			0
Other changes				16,519
Net income	399,189				399,189
Net (income) loss attributable to noncontrolling interests	(6,736)				(6,736)
Preferred share dividends	(10,403)				(10,403)
Loss on redemption of preferred shares	0				0
Unrealized holding gains (losses) during period, net of reclassification adjustment							20,547
Unrealized holding gains (losses) during period attributable to noncontrolling interests							1,019
Foreign currency translation adjustments	(16,424)							(16,424)
Foreign currency translation adjustments attributable to noncontrolling interests								(255)
Shares repurchased for treasury									(2,712)
Balance at end of period at Sep. 30, 2019	11,158,096	$ 780,000	$ 638	$ 1,864,468	$ 10,705,025	$ 211,714	$ 283,193	$ (71,479)	$ (2,403,749)	$ 0
Non-redeemable noncontrolling interests, end of period at Sep. 30, 2019	854,924
Total shareholders’ equity at Sep. 30, 2019	$ 12,013,020

Unaudited Consolidated Statem_4

Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating Activities
Net income	$ 1,380,532	$ 671,497
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized (gains) losses	(329,053)	224,757
Net impairment losses recognized in earnings	2,521	1,124
Equity in net income or loss of investment funds accounted for using the equity method and other income or loss	(38,912)	6,357
Amortization of intangible assets	60,214	79,523
Share-based compensation	54,432	45,806
Changes in:
Reserve for losses and loss adjustment expenses, net of unpaid losses and loss adjustment expenses recoverable	377,074	68,245
Unearned premiums, net of ceded unearned premiums	312,998	182,453
Premiums receivable	(328,765)	(203,247)
Deferred acquisition costs	(38,606)	(36,074)
Reinsurance balances payable	214,902	83,696
Other items, net	(124,198)	(3,150)
Net Cash Provided by (Used in) Operating Activities	1,543,139	1,120,987
Investing Activities
Purchases of fixed maturity investments	(24,010,623)	(24,837,917)
Purchases of equity securities	(524,051)	(819,342)
Purchases of other investments	(1,014,925)	(1,543,332)
Proceeds from sales of fixed maturity investments	22,707,854	23,310,203
Proceeds from sales of equity securities	371,130	866,919
Proceeds from sales, redemptions and maturities of other investments	827,517	1,178,035
Proceeds from redemptions and maturities of fixed maturity investments	394,719	724,021
Net settlements of derivative instruments	92,423	765
Net sales of short-term investments	129,078	554,315
Change in cash collateral related to securities lending	6,990	137,073
Purchases of fixed assets	(27,635)	(19,050)
Other	(202,953)	58,227
Net cash provided by (used for) investing activities	(1,250,476)	(390,083)
Financing Activities
Redemption of preferred shares	0	(92,555)
Purchases of common shares under share repurchase program	(2,871)	(184,529)
Proceeds from common shares issued, net	518	(12,029)
Proceeds from borrowings	200,083	167,259
Repayments of borrowings	(27,538)	(427,000)
Change in cash collateral related to securities lending	(6,990)	(137,073)
Change in third party investment in redeemable noncontrolling interests	(161,874)	0
Dividends paid to redeemable noncontrolling interests	(11,408)	(13,491)
Other	(5,207)	(6,084)
Preferred dividends paid	(31,209)	(31,242)
Net Cash Provided by (Used in) Financing Activities	(46,496)	(736,744)
Effects of exchange rate changes on foreign currency cash and restricted cash	(8,335)	(11,625)
Increase (decrease) in cash and restricted cash	237,832	(17,465)
Cash and restricted cash, beginning of year	724,643	727,284
Cash and restricted cash, end of period	$ 962,475	$ 709,819

Basis of Presentation and Recen

Basis of Presentation and Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Recent Accounting Pronouncements	Basis of Presentation and Recent Accounting Pronouncements General Arch Capital Group Ltd. (“Arch Capital”) is a Bermuda public limited liability company which provides insurance, reinsurance and mortgage insurance on a worldwide basis through its wholly-owned subsidiaries. As used herein, the “Company” means Arch Capital and its subsidiaries. The Company’s consolidated financial statements include the results of Watford Holdings Ltd. and its wholly owned subsidiaries (“Watford”). Watford is a multi-line Bermuda reinsurance company. Watford’s own management and board of directors are responsible for its results and profitability. See note 11 . On January 1, 2019, the Company’s U.K. insurance operations entered into a transaction with The Ardonagh Group to acquire renewal rights for a U.K. commercial lines book of business, consisting of commercial property, casualty, motor, professional liability, personal accident and travel business. Basis of Presentation The interim consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). All significant intercompany transactions and balances have been eliminated in consolidation. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ materially from those estimates and assumptions. In the opinion of management, the accompanying unaudited interim consolidated financial statements reflect all adjustments (consisting of normally recurring accruals) necessary for a fair statement of results on an interim basis. The results of any interim period are not necessarily indicative of the results for a full year or any future periods. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted; however, management believes that the disclosures are adequate to make the information presented not misleading. This report should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 (“2018 Form 10-K”), including the Company’s audited consolidated financial statements and related notes. The Company has reclassified the presentation of certain prior year information to conform to the current presentation. Such reclassifications had no effect on the Company’s net income, comprehensive income, shareholders’ equity or cash flows. Tabular amounts are in U.S. Dollars in thousands, except share amounts, unless otherwise noted. Recent Accounting Pronouncements Recently Issued Accounting Standards Adopted The Company adopted ASU 2016-02, “Leases (Topic 842)”, which provides a new comprehensive model for lease accounting. Topic 842 requires a lessee to recognize a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term. The Company adopted the modified retrospective approach of this standard, that resulted in the recognition of a right-of-use asset of $147.9 million as part of other assets and a lease liability of $163.6 million as part of other liabilities in the consolidated balance sheet as of January 1, 2019. The Company de-recognized the liability for deferred rent that was required under the previous guidance. In addition, the Company adopted ASU 2018-11, “Leases: Targeted Improvements (Topic 842),” which provides an additional (optional) transition method to adopt the new lease standard. The Company adopted the alternative transition method and elected to utilize a cumulative-effect adjustment to the opening balance of the retained earnings for the year of adoption. As such, the Company’s reporting for the comparative periods prior to the adoption continue to be presented in the financial statements in accordance with previous lease accounting guidance. The Company also adopted the practical expedients as a package which allows the Company to not reassess (1) whether any expired or existing contracts are or contain leases (2) the lease classification for any expired or existing leases (3) initial direct costs for any existing leases and (4) to account for the lease and non lease components as a single lease component. In addition to electing the practical expedients as a package, the Company elected to include hindsight to determine the lease term of existing leases, and made an accounting policy election to not apply the recognition requirements to short-term leases (lease term of less than twelve months). The cumulative effect adjustment to the opening balance of retained earnings was zero . The adoption of the updated guidance did not have a material effect on the Company’s results of operations or liquidity. The Company adopted ASU 2018-07 “Improvements to Nonemployee Share-Based Payment Accounting,” which was issued in June 2018 to simplify the accounting for share-based payments granted to nonemployees for goods and services. Under this ASU, most of the guidance on such payments to nonemployees would be aligned with the requirements for share-based payments granted to employees. The ASU is effective for reporting periods beginning after December 15, 2018. This guidance and the adoption of this provision did not have a material effect on the Company's financial position, results of operations or cash flows. The Company adopted ASU 2018-02 “Income Statement-Reporting Comprehensive Income (Topic 220) - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income,” which was issued in February 2018 to allow the reclassification of the stranded tax effects in accumulated other comprehensive income (“AOCI”) resulting from the Tax Cuts and Jobs Act of 2017 (“Tax Cuts Act”). Current guidance requires the effect of a change in tax laws or rates on deferred tax balances to be reported in income from continuing operations in the accounting period that includes the period of enactment, even if the related income tax effects were originally charged or credited directly to AOCI. The amount of the reclassification would include the effect of the change in the U.S. federal corporate income tax rate on the gross deferred tax amounts and related valuation allowances, if any, at the date of the enactment of the Tax Cuts Act related to items in AOCI. The updated guidance is effective for reporting periods beginning after December 15, 2018 and is to be applied retrospectively to each period in which the effect of the Tax Cuts Act related to items remaining in AOCI are recognized or at the beginning of the period of adoption. The adoption of this ASU did not have a material effect on the Company’s results of operations, financial position or liquidity. The Company adopted ASU 2017-08 “Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20), Premium Amortization on Purchased Callable Debt Securities,” which was issued in March, 2017. This ASU shortens the amortization period for certain callable debt securities held at a premium and requires the premium to be amortized to the earliest call date. However, the new guidance does not require an accounting change for securities held at a discount whose discount continues to be amortized to maturity. The standard is effective for financial statements issued for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. The adoption of the guidance requires a modified retrospective approach with a cumulative-effect adjustment to retained earnings. The adoption of this ASU did not have a material effect on the Company’s consolidated financial statements. Recently Issued Accounting Standards Not Yet Adopted For information regarding additional accounting standards that the Company has not yet adopted, see note 3(q), “Significant Accounting Policies—Recent Accounting Pronouncements,” of the notes to consolidated financial statements in the Company’s 2018 Form 10-K.

Share Transactions

Share Transactions	9 Months Ended
	Sep. 30, 2019
Stockholders' Equity Note [Abstract]
Share Transactions	Share Transactions Share Repurchases The board of directors of Arch Capital has authorized the investment in Arch Capital’s common shares through a share repurchase program. Since the inception of the share repurchase program, Arch Capital has repurchased 386.3 million common shares for an aggregate purchase price of $3.97 billion . For the nine months ended September 30, 2019 , Arch Capital repurchased 0.1 million shares under the share repurchase program with an aggregate purchase price of $2.9 million . Arch Capital repurchased 6.9 million shares under the share repurchase program with an aggregate purchase price of $184.5 million during the nine months ended September 30, 2018 . At September 30, 2019 , $160.9 million of share repurchases were available under the program, which may be effected from time to time in open market or privately negotiated transactions. The timing and amount of the repurchase transactions under this program will depend on a variety of factors, including market conditions and corporate and regulatory considerations. (see note 16). Conversion of Convertible Non-Voting Common Equivalent Preferred Shares In March 2018, Arch Capital completed an underwritten public secondary offering of 17.0 million common shares (split adjusted) by American International Group, Inc. (“AIG”) following transfer of 0.6 million Series D convertible non-voting common equivalent preferred shares (“Series D Preferred Shares”). Proceeds from the sale of common shares pursuant to the public offering were received by AIG. At September 30, 2019 , no Series D Preferred Shares were outstanding. Series C Preferred Shares On January 2, 2018, Arch Capital redeemed all outstanding 6.75% Series C non-cumulative preferred shares. The preferred shares were redeemed at a redemption price equal to $25 per share, plus all declared and unpaid dividends to (but excluding) the redemption date. In accordance with GAAP, following the redemption, original issuance costs related to such shares were removed from additional paid-in capital and recorded as a “loss on redemption of preferred shares.” Such adjustment had no impact on total shareholders’ equity or cash flows.

Earnings Per Common Share

Earnings Per Common Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share The following table sets forth the computation of basic and diluted earnings per common share: Three Months Ended Nine Months Ended September 30, September 30, 2019 2018 2019 2018 Numerator: Net income $ 399,189 $ 248,766 $ 1,380,532 $ 671,497 Amounts attributable to noncontrolling interests (6,736 ) (21,358 ) (70,597 ) (50,020 ) Net income available to Arch 392,453 227,408 1,309,935 621,477 Preferred dividends (10,403 ) (10,402 ) (31,209 ) (31,242 ) Loss on redemption of preferred shares — — — (2,710 ) Net income available to Arch common shareholders $ 382,050 $ 217,006 $ 1,278,726 $ 587,525 Denominator: Weighted average common shares outstanding 402,564,121 402,939,092 401,419,153 400,649,105 Series D preferred shares (1) — — — 4,427,123 Weighted average common shares and common share equivalents outstanding — basic 402,564,121 402,939,092 401,419,153 405,076,228 Effect of dilutive common share equivalents: Nonvested restricted shares 1,895,972 1,619,286 1,637,015 1,568,044 Stock options (2) 8,720,108 7,162,836 7,751,234 7,348,920 Weighted average common shares and common share equivalents outstanding — diluted 413,180,201 411,721,214 410,807,402 413,993,192 Earnings per common share: Basic $ 0.95 $ 0.54 $ 3.19 $ 1.45 Diluted $ 0.92 $ 0.53 $ 3.11 $ 1.42 (1) Such shares are convertible non-voting common equivalent preferred shares issued in connection with the UGC acquisition. See note 2 . (2) Certain stock options were not included in the computation of diluted earnings per share where the exercise price of the stock options exceeded the average market price and would have been anti-dilutive or where, when applying the treasury stock method to in-the-money options, the sum of the proceeds, including unrecognized compensation, exceeded the average market price and would have been anti-dilutive. For the 2019 third quarter and 2018 third quarter , the number of stock options excluded were 37,394 and 4,396,352 , respectively. For the nine months ended September 30, 2019 and 2018 period, the number of stock options excluded were 2,198,115 and 5,481,584 , respectively.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Segment Information	Segment Information The Company classifies its businesses into three underwriting segments — insurance, reinsurance and mortgage — and two other operating segments — ‘other’ and corporate (non-underwriting). The Company determined its reportable segments using the management approach described in accounting guidance regarding disclosures about segments of an enterprise and related information. The accounting policies of the segments are the same as those used for the preparation of the Company’s consolidated financial statements. Intersegment business is allocated to the segment accountable for the underwriting results. The Company’s insurance, reinsurance and mortgage segments each have managers who are responsible for the overall profitability of their respective segments and who are directly accountable to the Company’s chief operating decision makers, the President and Chief Executive Officer of Arch Capital, and the Chief Financial Officer of Arch Capital. The chief operating decision makers do not assess performance, measure return on equity or make resource allocation decisions on a line of business basis. Management measures segment performance for its three underwriting segments based on underwriting income or loss. The Company does not manage its assets by underwriting segment, with the exception of goodwill and intangible assets, and, accordingly, investment income is not allocated to each underwriting segment. The insurance segment consists of the Company’s insurance underwriting units which offer specialty product lines on a worldwide basis. Product lines include: construction and national accounts; excess and surplus casualty; lenders products; professional lines; programs; property, energy, marine and aviation; travel, accident and health; and other (consisting of alternative markets, excess workers' compensation and surety business). The reinsurance segment consists of the Company’s reinsurance underwriting units which offer specialty product lines on a worldwide basis. Product lines include: casualty; marine and aviation; other specialty; property catastrophe; property excluding property catastrophe (losses on a single risk, both excess of loss and pro rata); and other (consisting of life reinsurance, casualty clash and other). The mortgage segment includes the Company’s U.S. and international mortgage insurance and reinsurance operations as well as government sponsored enterprise (“GSE”) credit-risk sharing transactions. Arch Mortgage Insurance Company and United Guaranty Residential Insurance Company (combined “Arch MI U.S.”) are approved as eligible mortgage insurers by Federal National Mortgage Association (“Fannie Mae”) and Federal Home Loan Mortgage Corporation (“Freddie Mac”), each a GSE. The corporate (non-underwriting) segment results include net investment income, other income (loss), corporate expenses, transaction costs and other, interest expense, items related to the Company’s non-cumulative preferred shares, net realized gains or losses, net impairment losses included in earnings, equity in net income or loss of investment funds accounted for using the equity method, net foreign exchange gains or losses and income taxes. Such amounts exclude the results of the ‘other’ segment. The ‘other’ segment includes the results of Watford (see note 11 ). For the ‘other’ segment, performance is measured based on net income or loss. The following tables summarize the Company’s underwriting income or loss by segment, together with a reconciliation of underwriting income or loss to net income available to Arch common shareholders: Three Months Ended September 30, 2019 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 1,005,874 $ 662,572 $ 375,092 $ 2,043,292 $ 249,960 $ 2,181,121 Premiums ceded (302,034 ) (226,096 ) (57,703 ) (585,587 ) (94,208 ) (567,664 ) Net premiums written 703,840 436,476 317,389 1,457,705 155,752 1,613,457 Change in unearned premiums (98,504 ) (72,621 ) 25,611 (145,514 ) (29,920 ) (175,434 ) Net premiums earned 605,336 363,855 343,000 1,312,191 125,832 1,438,023 Other underwriting income (loss) — (1,208 ) 3,955 2,747 579 3,326 Losses and loss adjustment expenses (422,782 ) (270,379 ) (13,080 ) (706,241 ) (96,214 ) (802,455 ) Acquisition expenses (91,259 ) (62,393 ) (34,396 ) (188,048 ) (23,072 ) (211,120 ) Other operating expenses (115,408 ) (32,533 ) (37,003 ) (184,944 ) (11,568 ) (196,512 ) Underwriting income (loss) $ (24,113 ) $ (2,658 ) $ 262,476 235,705 (4,443 ) 231,262 Net investment income 126,874 34,614 161,488 Net realized gains (losses) 81,177 (18,659 ) 62,518 Net impairment losses recognized in earnings (1,163 ) — (1,163 ) Equity in net income (loss) of investment funds accounted for using the equity method 17,130 — 17,130 Other income (loss) 1,338 — 1,338 Corporate expenses (2) (15,066 ) — (15,066 ) Transaction costs and other (2) (1,995 ) — (1,995 ) Amortization of intangible assets (20,003 ) — (20,003 ) Interest expense (23,237 ) (8,091 ) (31,328 ) Net foreign exchange gains (losses) 29,794 3,330 33,124 Income before income taxes 430,554 6,751 437,305 Income tax expense (38,116 ) — (38,116 ) Net income 392,438 6,751 399,189 Dividends attributable to redeemable noncontrolling interests — (6,600 ) (6,600 ) Amounts attributable to nonredeemable noncontrolling interests — (136 ) (136 ) Net income available to Arch 392,438 15 392,453 Preferred dividends (10,403 ) — (10,403 ) Net income available to Arch common shareholders $ 382,035 $ 15 $ 382,050 Underwriting Ratios Loss ratio 69.8 % 74.3 % 3.8 % 53.8 % 76.5 % 55.8 % Acquisition expense ratio 15.1 % 17.1 % 10.0 % 14.3 % 18.3 % 14.7 % Other operating expense ratio 19.1 % 8.9 % 10.8 % 14.1 % 9.2 % 13.7 % Combined ratio 104.0 % 100.3 % 24.6 % 82.2 % 104.0 % 84.2 % Goodwill and intangible assets $ 158,990 $ — $ 457,860 $ 616,850 $ 7,650 $ 624,500 (1) Certain amounts included in the gross premiums written of each segment are related to intersegment transactions. Accordingly, the sum of gross premiums written for each segment does not agree to the total gross premiums written as shown in the table above due to the elimination of intersegment transactions in the total. (2) Certain expenses have been excluded from ‘corporate expenses’ and reflected in ‘transaction costs and other.’ Three Months Ended September 30, 2018 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 836,820 $ 435,396 $ 350,559 $ 1,622,532 $ 185,033 $ 1,731,328 Premiums ceded (259,968 ) (123,705 ) (57,226 ) (440,656 ) (33,356 ) (397,775 ) Net premiums written 576,852 311,691 293,333 1,181,876 151,677 1,333,553 Change in unearned premiums (15,794 ) (18,418 ) 7,591 (26,621 ) (16,054 ) (42,675 ) Net premiums earned 561,058 293,273 300,924 1,155,255 135,623 1,290,878 Other underwriting income (loss) — 1,387 3,733 5,120 703 5,823 Losses and loss adjustment expenses (409,435 ) (183,413 ) (9,615 ) (602,463 ) (96,957 ) (699,420 ) Acquisition expenses (88,255 ) (50,367 ) (33,361 ) (171,983 ) (29,619 ) (201,602 ) Other operating expenses (90,081 ) (29,936 ) (31,122 ) (151,139 ) (9,959 ) (161,098 ) Underwriting income (loss) $ (26,713 ) $ 30,944 $ 230,559 234,790 (209 ) 234,581 Net investment income 114,328 29,696 144,024 Net realized gains (losses) (47,010 ) (4,695 ) (51,705 ) Net impairment losses recognized in earnings (492 ) — (492 ) Equity in net income (loss) of investment funds accounted for using the equity method 15,982 — 15,982 Other income (loss) (726 ) — (726 ) Corporate expenses (2) (13,244 ) — (13,244 ) Transaction costs and other (2) (1,091 ) — (1,091 ) Amortization of intangible assets (26,315 ) — (26,315 ) Interest expense (24,666 ) (5,064 ) (29,730 ) Net foreign exchange gains (losses) 7,130 3,708 10,838 Income before income taxes 258,686 23,436 282,122 Income tax expense (33,356 ) — (33,356 ) Net income 225,330 23,436 248,766 Dividends attributable to redeemable noncontrolling interests — (4,599 ) (4,599 ) Amounts attributable to nonredeemable noncontrolling interests — (16,759 ) (16,759 ) Net income available to Arch 225,330 2,078 227,408 Preferred dividends (10,402 ) — (10,402 ) Net income available to Arch common shareholders $ 214,928 $ 2,078 $ 217,006 Underwriting Ratios Loss ratio 73.0 % 62.5 % 3.2 % 52.1 % 71.5 % 54.2 % Acquisition expense ratio 15.7 % 17.2 % 11.1 % 14.9 % 21.8 % 15.6 % Other operating expense ratio 16.1 % 10.2 % 10.3 % 13.1 % 7.3 % 12.5 % Combined ratio 104.8 % 89.9 % 24.6 % 80.1 % 100.6 % 82.3 % Goodwill and intangible assets $ 20,141 $ — $ 538,871 $ 559,012 $ 7,650 $ 566,662 (1) Certain amounts included in the gross premiums written of each segment are related to intersegment transactions. Accordingly, the sum of gross premiums written for each segment does not agree to the total gross premiums written as shown in the table above due to the elimination of intersegment transactions in the total. (2) Certain expenses have been excluded from ‘corporate expenses’ and reflected in ‘transaction costs and other.’ Nine Months Ended September 30, 2019 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 2,867,753 $ 1,890,974 $ 1,095,607 $ 5,853,574 $ 598,627 $ 6,196,809 Premiums ceded (914,751 ) (627,120 ) (149,358 ) (1,690,469 ) (178,118 ) (1,613,195 ) Net premiums written 1,953,002 1,263,854 946,249 4,163,105 420,509 4,583,614 Change in unearned premiums (201,719 ) (186,450 ) 72,436 (315,733 ) 2,735 (312,998 ) Net premiums earned 1,751,283 1,077,404 1,018,685 3,847,372 423,244 4,270,616 Other underwriting income (loss) — 4,393 11,867 16,260 1,844 18,104 Losses and loss adjustment expenses (1,168,677 ) (751,147 ) (50,226 ) (1,970,050 ) (318,480 ) (2,288,530 ) Acquisition expenses (265,177 ) (173,504 ) (98,722 ) (537,403 ) (81,654 ) (619,057 ) Other operating expenses (338,327 ) (102,197 ) (116,697 ) (557,221 ) (39,368 ) (596,589 ) Underwriting income (loss) $ (20,898 ) $ 54,949 $ 764,907 798,958 (14,414 ) 784,544 Net investment income 371,161 102,314 473,475 Net realized gains (losses) 318,722 6,167 324,889 Net impairment losses recognized in earnings (2,521 ) — (2,521 ) Equity in net income (loss) of investment funds accounted for using the equity method 96,533 — 96,533 Other income (loss) 3,550 — 3,550 Corporate expenses (2) (47,911 ) — (47,911 ) Transaction costs and other (2) (5,363 ) — (5,363 ) Amortization of intangible assets (60,214 ) — (60,214 ) Interest expense (70,094 ) (19,579 ) (89,673 ) Net foreign exchange gains (losses) 28,779 2,918 31,697 Income before income taxes 1,431,600 77,406 1,509,006 Income tax expense (128,454 ) (20 ) (128,474 ) Net income 1,303,146 77,386 1,380,532 Dividends attributable to redeemable noncontrolling interests — (15,778 ) (15,778 ) Amounts attributable to nonredeemable noncontrolling interests — (54,819 ) (54,819 ) Net income available to Arch 1,303,146 6,789 1,309,935 Preferred dividends (31,209 ) — (31,209 ) Net income available to Arch common shareholders $ 1,271,937 $ 6,789 $ 1,278,726 Underwriting Ratios Loss ratio 66.7 % 69.7 % 4.9 % 51.2 % 75.2 % 53.6 % Acquisition expense ratio 15.1 % 16.1 % 9.7 % 14.0 % 19.3 % 14.5 % Other operating expense ratio 19.3 % 9.5 % 11.5 % 14.5 % 9.3 % 14.0 % Combined ratio 101.1 % 95.3 % 26.1 % 79.7 % 103.8 % 82.1 % (1) Certain amounts included in the gross premiums written of each segment are related to intersegment transactions. Accordingly, the sum of gross premiums written for each segment does not agree to the total gross premiums written as shown in the table above due to the elimination of intersegment transactions in the total. (2) Certain expenses have been excluded from ‘corporate expenses’ and reflected in ‘transaction costs and other.’ Nine Months Ended September 30, 2018 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 2,429,570 $ 1,503,206 $ 1,002,727 $ 4,935,339 $ 574,078 $ 5,266,086 Premiums ceded (752,413 ) (455,682 ) (154,230 ) (1,362,161 ) (102,263 ) (1,221,093 ) Net premiums written 1,677,157 1,047,524 848,497 3,573,178 471,815 4,044,993 Change in unearned premiums (30,913 ) (134,761 ) 23,147 (142,527 ) (39,926 ) (182,453 ) Net premiums earned 1,646,244 912,763 871,644 3,430,651 431,889 3,862,540 Other underwriting income (loss) — 2,490 10,464 12,954 2,092 15,046 Losses and loss adjustment expenses (1,120,630 ) (555,044 ) (74,672 ) (1,750,346 ) (312,087 ) (2,062,433 ) Acquisition expenses (264,094 ) (148,828 ) (87,665 ) (500,587 ) (95,229 ) (595,816 ) Other operating expenses (274,735 ) (101,185 ) (108,622 ) (484,542 ) (27,752 ) (512,294 ) Underwriting income (loss) $ (13,215 ) $ 110,196 $ 611,149 708,130 (1,087 ) 707,043 Net investment income 322,332 84,084 406,416 Net realized gains (losses) (218,414 ) (20,900 ) (239,314 ) Net impairment losses recognized in earnings (1,124 ) — (1,124 ) Equity in net income (loss) of investment funds accounted for using the equity method 52,523 — 52,523 Other income (loss) 2,461 — 2,461 Corporate expenses (2) (43,330 ) — (43,330 ) Transaction costs and other (2) (8,829 ) — (8,829 ) Amortization of intangible assets (79,523 ) — (79,523 ) Interest expense (76,631 ) (14,079 ) (90,710 ) Net foreign exchange gains (losses) 38,302 6,521 44,823 Income before income taxes 695,897 54,539 750,436 Income tax expense (78,912 ) (27 ) (78,939 ) Net income 616,985 54,512 671,497 Dividends attributable to redeemable noncontrolling interests — (13,769 ) (13,769 ) Amounts attributable to nonredeemable noncontrolling interests — (36,251 ) (36,251 ) Net income available to Arch 616,985 4,492 621,477 Preferred dividends (31,242 ) — (31,242 ) Loss on redemption of preferred shares (2,710 ) — (2,710 ) Net income available to Arch common shareholders $ 583,033 $ 4,492 $ 587,525 Underwriting Ratios Loss ratio 68.1 % 60.8 % 8.6 % 51.0 % 72.3 % 53.4 % Acquisition expense ratio 16.0 % 16.3 % 10.1 % 14.6 % 22.0 % 15.4 % Other operating expense ratio 16.7 % 11.1 % 12.5 % 14.1 % 6.4 % 13.3 % Combined ratio 100.8 % 88.2 % 31.2 % 79.7 % 100.7 % 82.1 % (1) Certain amounts included in the gross premiums written of each segment are related to intersegment transactions. Accordingly, the sum of gross premiums written for each segment does not agree to the total gross premiums written as shown in the table above due to the elimination of intersegment transactions in the total. (2)

Reserve for Losses and Loss Adj

Reserve for Losses and Loss Adjustment Expenses	9 Months Ended
	Sep. 30, 2019
Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract]
Reserve for losses and loss adjustment expenses	Reserve for Losses and Loss Adjustment Expenses The following table represents an analysis of losses and loss adjustment expenses and a reconciliation of the beginning and ending reserve for losses and loss adjustment expenses: Three Months Ended Nine Months Ended September 30, September 30, 2019 2018 2019 2018 Reserve for losses and loss adjustment expenses at beginning of period $ 12,230,316 $ 11,424,337 $ 11,853,297 $ 11,383,792 Unpaid losses and loss adjustment expenses recoverable 3,024,797 2,651,749 2,814,291 2,464,910 Net reserve for losses and loss adjustment expenses at beginning of period 9,205,519 8,772,588 9,039,006 8,918,882 Net incurred losses and loss adjustment expenses relating to losses occurring in: Current year 855,352 779,043 2,419,044 2,257,670 Prior years (52,897 ) (79,623 ) (130,514 ) (195,237 ) Total net incurred losses and loss adjustment expenses 802,455 699,420 2,288,530 2,062,433 Retroactive reinsurance transactions (1) — — (225,500 ) (420,404 ) Net foreign exchange (gains) losses (73,200 ) (33,783 ) (74,981 ) (110,061 ) Net paid losses and loss adjustment expenses relating to losses occurring in: Current year (175,611 ) (149,999 ) (301,099 ) (245,021 ) Prior years (399,948 ) (396,695 ) (1,366,741 ) (1,314,298 ) Total net paid losses and loss adjustment expenses (575,559 ) (546,694 ) (1,667,840 ) (1,559,319 ) Net reserve for losses and loss adjustment expenses at end of period 9,359,215 8,891,531 9,359,215 8,891,531 Unpaid losses and loss adjustment expenses recoverable 3,030,169 2,662,790 3,030,169 2,662,790 Reserve for losses and loss adjustment expenses at end of period $ 12,389,384 $ 11,554,321 $ 12,389,384 $ 11,554,321 (1) During the 2019 first quarter and 2018 second quarter, a subsidiary of the Company entered into two separate retroactive reinsurance transactions with third party reinsurers to reinsure run-off liabilities associated with certain U.S. insurance exposures. Development on Prior Year Loss Reserves 2019 Third Quarter During the 2019 third quarter , the Company recorded net favorable development on prior year loss reserves of $52.9 million , which consisted of $4.4 million of favorable development from the insurance segment, $15.3 million from the reinsurance segment, $33.0 million from the mortgage segment and $0.2 million from the ‘other’ segment. The insurance segment’s net favorable development of $4.4 million , or 0.7 loss ratio points, for the 2019 third quarter consisted of $24.8 million of net favorable development in short-tailed lines and $20.4 million of net adverse development in medium-tailed and long-tailed lines. Net favorable development in short-tailed lines primarily resulted from lenders products and property (including special risk other than marine) reserves across all accident years ( i.e. , the year in which a loss occurred). Net adverse development in medium-tailed and long-tailed lines included $6.3 million of adverse development in executive assurance reserves, primarily from the 2016 to 2018 accident years, $4.9 million of adverse development on casualty reserves, primarily related to contract binding business across most accident years, $4.2 million of adverse development on program business, primarily from the 2018 accident year, and $3.8 million in healthcare reserves, primarily from the 2016 to 2018 accident years. The reinsurance segment’s net favorable development of $15.3 million , or 4.2 loss ratio points, for the 2019 third quarter consisted of $35.2 million of net favorable development from short-tailed and medium-tailed lines and net adverse development of $19.9 million from long-tailed lines. Net favorable development in short-tailed and medium lines reflected $26.5 million of favorable development from property catastrophe and property other than property catastrophe reserves, primarily related to 2017 and 2018 catastrophic events, and favorable development on marine and aviation and other reserves across most underwriting years ( i.e. , all premiums and losses attributable to contracts having an inception or renewal date within the given twelve-month period). Adverse development in long-tailed lines reflected an increase in reserves from casualty from various underwriting years. The mortgage segment’s net favorable development was $33.0 million , or 9.6 loss ratio points, for the 2019 third quarter . The 2019 third quarter development was primarily driven by continued favorable claim rates on first lien business and subrogation recoveries on second lien business. 2018 Third Quarter During the 2018 third quarter , the Company recorded net favorable development on prior year loss reserves of $79.6 million , which consisted of $5.9 million from the insurance segment, $34.3 million from the reinsurance segment, $38.6 million from the mortgage segment and $0.7 million from the ‘other’ segment. The insurance segment’s net favorable development of $5.9 million , or 1.1 loss ratio points, for the 2018 third quarter consisted of $14.3 million of net favorable development in short-tailed lines and $8.4 million of net adverse development in medium-tailed and long-tailed lines. Net favorable development in short-tailed lines primarily resulted from property (including special risk other than marine) reserves from the 2017 accident year (i.e., the year in which a loss occurred) while net adverse development in medium-tailed and long-tailed lines primarily resulted from $16.4 million of adverse development on contract binding business, primarily from the 2015 to 2017 accident years. Such amounts were partially offset by $8.0 million of net favorable development in other medium-tailed and short-tailed lines, including professional liability and surety business, across most accident years. The reinsurance segment’s net favorable development of $34.3 million , or 11.7 loss ratio points, for the 2018 third quarter consisted of $26.5 million from short-tailed lines and $7.8 million from long-tailed and medium-tailed lines. Favorable development in short-tailed lines included $15.9 million from property catastrophe and property other than property catastrophe reserves, across most underwriting years (i.e., all premiums and losses attributable to contracts having an inception or renewal date within the given twelve-month period), reflecting lower levels of reported and paid claims activity than previously anticipated which led to decreases in certain loss ratio selections during the period, and $10.3 million from other specialty reserves, primarily from the 2016 underwriting year. Favorable development in long-tailed and medium-tailed lines reflected reductions in casualty reserves of $7.9 million based on varying levels of reported and paid claims activity, primarily from the 2009 underwriting year. The mortgage segment’s net favorable development was $38.6 million , or 12.8 loss ratio points, for the 2018 third quarter . The 2018 third quarter development was primarily driven by lower than expected claim rates on first lien business and subrogation recoveries on second lien business. Nine Months Ended September 30, 2019 During the nine months ended September 30, 2019 , the Company recorded net favorable development on prior year loss reserves of $130.5 million , which consisted of $11.4 million from the insurance segment, $26.3 million from the reinsurance segment, $92.5 million from the mortgage segment and $0.3 million from the ‘other’ segment. The insurance segment’s net favorable development of $11.4 million , or 0.7 loss ratio points, for the 2019 period consisted of $42.6 million of net favorable development in short-tailed lines, partially offset by $31.2 million of net adverse development in medium-tailed and long-tailed lines. Net favorable development in short-tailed lines primarily resulted from lenders products and property (including special risk other than marine) reserves across all accident years, partially offset by net adverse development in travel business, primarily from the 2018 accident year. Net adverse development in medium-tailed and long-tailed lines reflected $27.4 million of adverse development in program business, primarily from the 2018 accident year, and $12.8 million of adverse development on casualty business, primarily from contract binding business across most accident years. Such amounts were partially offset by $9.0 million of net favorable development in other medium-tailed and long-tailed lines, including professional liability, marine and surety business, across most accident years. The reinsurance segment’s net favorable development of $26.3 million , or 2.4 loss ratio points, for the 2019 period consisted of $37.1 million of net favorable development from short-tailed and medium-tailed lines, offset by $10.8 million of net adverse development from long-tailed lines. Net favorable development in short-tailed lines reflected $22.6 million from other specialty lines and $9.5 million from property catastrophe reserves. Favorable development in medium-tailed lines reflected reductions in marine and aviation reserves of $10.4 million across most underwriting years. The mortgage segment’s net favorable development was $92.5 million , or 9.1 loss ratio points, for the 2019 period. The 2019 development was primarily driven by continued lower than expected claim rates on first lien business and subrogation recoveries on second lien business. Nine Months Ended September 30, 2018 During the nine months ended September 30, 2018 , the Company recorded net favorable development on prior year loss reserves of $195.2 million , which consisted of $14.1 million from the insurance segment, $103.9 million from the reinsurance segment, $74.9 million from the mortgage segment and $2.3 million from the ‘other’ segment. The insurance segment’s net favorable development of $14.1 million , or 0.9 loss ratio points, for the 2018 period consisted of $37.0 million of net favorable development in short-tailed lines and $16.4 million of net favorable development in long-tailed lines, partially offset by $39.3 million of net adverse development in medium-tailed lines. Net favorable development in short-tailed lines primarily resulted from property (including special risk other than marine) reserves from the 2010 and 2017 accident years. Net favorable development in long-tailed lines reflected net reductions in executive assurance reserves of $8.0 million , primarily from the 2008 accident year, and in healthcare reserves of $8.1 million , primarily from the 2003 accident year. Net adverse development in medium-tailed lines reflected $23.4 million of adverse development in program business, primarily driven by a few inactive programs that were non-renewed in prior periods and $42.1 million of adverse development on contract binding business, primarily from the 2014 to 2017 accident years. Such amounts were partially offset by $26.2 million of net favorable development in other medium-tailed lines, including professional liability and surety business, across most accident years. The reinsurance segment’s net favorable development of $103.9 million , or 11.4 loss ratio points, for the 2018 period consisted of $77.6 million from short-tailed lines and $26.3 million from long-tailed and medium-tailed lines. Favorable development in short-tailed lines included $56.4 million from property catastrophe and property other than property catastrophe reserves, across most underwriting years, reflecting lower levels of reported and paid claims activity than previously anticipated which led to decreases in certain loss ratio selections during the period, and $10.7 million from other specialty reserves, across most underwriting years. Favorable development in long-tailed and medium-tailed lines reflected reductions in casualty reserves of $16.0 million based on varying levels of reported and paid claims activity, primarily from the 2002 to 2010 underwriting years, and favorable development in marine reserves of $10.8 million across most underwriting years. The mortgage segment’s net favorable development was $74.9 million , or 8.6 loss ratio points, for the 2018 period. The 2018 development was primarily driven by lower than expected claim rates on first lien business and subrogation recoveries on second lien business.

Investment Information

Investment Information	9 Months Ended
	Sep. 30, 2019
Disclosure Investment Information [Abstract]
Investment Information	Investment Information At September 30, 2019 , total investable assets of $24.30 billion included $21.57 billion held by the Company and $2.73 billion attributable to Watford. Available For Sale Investments The following table summarizes the fair value and cost or amortized cost of the Company’s securities classified as available for sale: Estimated Fair Value Gross Unrealized Gains Gross Unrealized Losses Cost or Amortized Cost OTTI Unrealized Losses (2) September 30, 2019 Fixed maturities (1): Corporate bonds $ 6,269,993 $ 198,742 $ (18,420 ) $ 6,089,671 $ — Mortgage backed securities 544,033 11,185 (918 ) 533,766 (6 ) Municipal bonds 653,346 27,095 (379 ) 626,630 — Commercial mortgage backed securities 754,306 27,523 (158 ) 726,941 — U.S. government and government agencies 5,127,290 67,957 (6,671 ) 5,066,004 — Non-U.S. government securities 1,873,856 48,212 (52,767 ) 1,878,411 — Asset backed securities 1,657,494 29,838 (5,931 ) 1,633,587 — Total 16,880,318 410,552 (85,244 ) 16,555,010 (6 ) Short-term investments 751,989 227 (445 ) 752,207 — Total $ 17,632,307 $ 410,779 $ (85,689 ) $ 17,307,217 $ (6 ) December 31, 2018 Fixed maturities (1): Corporate bonds $ 5,537,548 $ 14,476 $ (105,428 ) $ 5,628,500 $ (69 ) Mortgage backed securities 541,193 3,991 (3,216 ) 540,418 (6 ) Municipal bonds 1,013,395 5,380 (11,891 ) 1,019,906 — Commercial mortgage backed securities 729,442 2,650 (10,751 ) 737,543 — U.S. government and government agencies 3,758,698 27,189 (8,474 ) 3,739,983 — Non-U.S. government securities 1,771,338 14,477 (50,948 ) 1,807,809 — Asset backed securities 1,600,896 8,060 (14,798 ) 1,607,634 — Total 14,952,510 76,223 (205,506 ) 15,081,793 (75 ) Short-term investments 955,880 36 (394 ) 956,238 — Total $ 15,908,390 $ 76,259 $ (205,900 ) $ 16,038,031 $ (75 ) (1) In securities lending transactions, the Company receives collateral in excess of the fair value of the fixed maturities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See “—Securities Lending Agreements.” (2) Represents the total other-than-temporary impairments (“OTTI”) recognized in accumulated other comprehensive income (“AOCI”). It does not include the change in fair value subsequent to the impairment measurement date. At September 30, 2019 the net unrealized loss related to securities for which a non-credit OTTI was recognized in AOCI was $0.01 million , compared to net unrealized loss of $0.04 million at December 31, 2018 . The following table summarizes, for all available for sale securities in an unrealized loss position, the fair value and gross unrealized loss by length of time the security has been in a continual unrealized loss position: Less than 12 Months 12 Months or More Total Estimated Gross Unrealized Losses Estimated Gross Unrealized Losses Estimated Gross Unrealized Losses September 30, 2019 Fixed maturities (1): Corporate bonds $ 538,471 $ (11,128 ) $ 113,987 $ (7,292 ) $ 652,458 $ (18,420 ) Mortgage backed securities 97,288 (905 ) 200 (13 ) 97,488 (918 ) Municipal bonds 43,627 (379 ) — — 43,627 (379 ) Commercial mortgage backed securities 47,219 (151 ) 1,872 (7 ) 49,091 (158 ) U.S. government and government agencies 1,592,232 (6,531 ) 47,416 (140 ) 1,639,648 (6,671 ) Non-U.S. government securities 1,214,128 (51,742 ) 47,576 (1,025 ) 1,261,704 (52,767 ) Asset backed securities 375,936 (4,600 ) 48,743 (1,331 ) 424,679 (5,931 ) Total 3,908,901 (75,436 ) 259,794 (9,808 ) 4,168,695 (85,244 ) Short-term investments 43,007 (445 ) — — 43,007 (445 ) Total $ 3,951,908 $ (75,881 ) $ 259,794 $ (9,808 ) $ 4,211,702 $ (85,689 ) December 31, 2018 Fixed maturities (1): Corporate bonds $ 2,983,195 $ (68,910 ) $ 1,234,865 $ (36,518 ) $ 4,218,060 $ (105,428 ) Mortgage backed securities 84,296 (695 ) 109,009 (2,521 ) 193,305 (3,216 ) Municipal bonds 233,081 (2,074 ) 408,155 (9,817 ) 641,236 (11,891 ) Commercial mortgage backed securities 223,341 (2,831 ) 193,956 (7,920 ) 417,297 (10,751 ) U.S. government and government agencies 635,049 (1,354 ) 391,102 (7,120 ) 1,026,151 (8,474 ) Non-U.S. government securities 1,028,340 (35,524 ) 389,671 (15,424 ) 1,418,011 (50,948 ) Asset backed securities 533,592 (8,832 ) 368,095 (5,966 ) 901,687 (14,798 ) Total 5,720,894 (120,220 ) 3,094,853 (85,286 ) 8,815,747 (205,506 ) Short-term investments 122,878 (394 ) — — 122,878 (394 ) Total $ 5,843,772 $ (120,614 ) $ 3,094,853 $ (85,286 ) $ 8,938,625 $ (205,900 ) (1) In securities lending transactions, the Company receives collateral in excess of the fair value of the fixed maturities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See “—Securities Lending Agreements.” At September 30, 2019 , on a lot level basis, approximately 1,980 security lots out of a total of approximately 9,260 security lots were in an unrealized loss position and the largest single unrealized loss from a single lot in the Company’s fixed maturity portfolio was $3.0 million . At December 31, 2018 , on a lot level basis, approximately 5,870 security lots out of a total of approximately 8,450 security lots were in an unrealized loss position and the largest single unrealized loss from a single lot in the Company’s fixed maturity portfolio was $2.6 million . The contractual maturities of the Company’s fixed maturities are shown in the following table. Expected maturities, which are management’s best estimates, will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. September 30, 2019 December 31, 2018 Maturity Estimated Fair Value Amortized Cost Estimated Amortized Cost Due in one year or less $ 545,056 $ 538,903 $ 276,682 $ 279,135 Due after one year through five years 10,096,867 9,971,896 8,666,297 8,738,944 Due after five years through 10 years 3,075,318 2,952,478 2,919,232 2,951,582 Due after 10 years 207,244 197,439 218,768 226,537 13,924,485 13,660,716 12,080,979 12,196,198 Mortgage backed securities 544,033 533,766 541,193 540,418 Commercial mortgage backed securities 754,306 726,941 729,442 737,543 Asset backed securities 1,657,494 1,633,587 1,600,896 1,607,634 Total (1) $ 16,880,318 $ 16,555,010 $ 14,952,510 $ 15,081,793 (1) In securities lending transactions, the Company receives collateral in excess of the fair value of the securities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See “—Securities Lending Agreements.” Securities Lending Agreements The Company enters into securities lending agreements with financial institutions to enhance investment income whereby it loans certain of its securities to third parties, primarily major brokerage firms, for short periods of time through a lending agent. The Company maintains legal control over the securities it lends, retains the earnings and cash flows associated with the loaned securities and receives a fee from the borrower for the temporary use of the securities. An indemnification agreement with the lending agent protects the Company in the event a borrower becomes insolvent or fails to return any of the securities on loan from the Company. The Company receives collateral in the form of cash or securities. Cash collateral primarily consists of short term investments. At September 30, 2019 , the fair value of the cash collateral received on securities lending was $12.0 million and the fair value of security collateral received was $418.2 million . At December 31, 2018 , the fair value of the cash collateral received on securities lending was $19.0 million , and the fair value of security collateral received was $255.1 million . The Company’s securities lending transactions were accounted for as secured borrowings with significant investment categories as follows: Remaining Contractual Maturity of the Agreements Overnight and Continuous Less than 30 Days 30-90 Days 90 Days or More Total September 30, 2019 U.S. government and government agencies $ 257,979 $ — $ 156,541 $ — $ 414,520 Corporate bonds 4,820 — — — 4,820 Equity securities 10,915 — — — 10,915 Total $ 273,714 $ — $ 156,541 $ — $ 430,255 Gross amount of recognized liabilities for securities lending in offsetting disclosure in note 8 $ — Amounts related to securities lending not included in offsetting disclosure in note 8 $ 430,255 December 31, 2018 U.S. government and government agencies $ 219,276 $ — $ 32,583 $ — $ 251,859 Corporate bonds 7,129 — — — 7,129 Equity securities 15,137 — — — 15,137 Total $ 241,542 $ — $ 32,583 $ — $ 274,125 Gross amount of recognized liabilities for securities lending in offsetting disclosure in note 8 $ — Amounts related to securities lending not included in offsetting disclosure in note 8 $ 274,125 Equity Securities, at Fair Value At September 30, 2019 , the Company held $550.5 million of equity securities, at fair value, compared to $338.9 million at December 31, 2018 . Such holdings include publicly traded common stocks in the natural resources, energy, consumer staples and other sectors and exchange-traded funds. Other Investments The following table summarizes the Company’s other investments which are included in investments accounted for using the fair value option, by strategy: September 30, December 31, Term loan investments (par value: $1,434,328 and $1,369,216) $ 1,330,886 $ 1,282,287 Lending 624,699 524,112 Credit related funds 165,444 202,123 Energy 113,791 117,509 Investment grade fixed income 83,649 101,902 Infrastructure 49,602 45,371 Private equity 54,609 24,383 Real estate 17,440 14,252 Total $ 2,440,120 $ 2,311,939 Investments Accounted For Using the Equity Method The following table summarizes the Company’s investments accounted for using the equity method, by strategy: September 30, December 31, Credit related funds $ 428,353 $ 429,402 Equities 284,465 375,273 Real estate 265,502 232,647 Lending 200,112 125,041 Private equity 141,343 114,019 Infrastructure 149,005 113,748 Energy 107,052 103,661 Total $ 1,575,832 $ 1,493,791 Certain of the Company’s other investments are in investment funds for which the Company has the option to redeem at agreed upon values as described in each investment fund’s subscription agreement. Depending on the terms of the various subscription agreements, investments in investment funds may be redeemed daily, monthly, quarterly or on other terms. Two common redemption restrictions which may impact the Company’s ability to redeem these investment funds are gates and lockups. A gate is a suspension of redemptions which may be implemented by the general partner or investment manager of the fund in order to defer, in whole or in part, the redemption request in the event the aggregate amount of redemption requests exceeds a predetermined percentage of the investment fund’s net assets which may otherwise hinder the general partner or investment manager’s ability to liquidate holdings in an orderly fashion in order to generate the cash necessary to fund extraordinarily large redemption payouts. A lockup period is the initial amount of time an investor is contractually required to hold the security before having the ability to redeem. If the investment funds are eligible to be redeemed, the time to redeem such fund can take weeks or months following the notification. Fair Value Option The following table summarizes the Company’s assets which are accounted for using the fair value option: September 30, December 31, Fixed maturities $ 908,802 $ 1,245,562 Other investments 2,440,120 2,311,939 Short-term investments 390,980 322,177 Equity securities 98,341 103,893 Investments accounted for using the fair value option $ 3,838,243 $ 3,983,571 Limited Partnership Interests In the normal course of its activities, the Company invests in limited partnerships as part of its overall investment strategy. Such amounts are included in ‘investments accounted for using the equity method’ and ‘investments accounted for using the fair value option.’ The Company has determined that it is not required to consolidate these investments because it is not the primary beneficiary of the funds. The Company’s maximum exposure to loss with respect to these investments is limited to the investment carrying amounts reported in the Company’s consolidated balance sheet and any unfunded commitment. The following table summarizes investments in limited partnership interests where the Company has a variable interest by balance sheet line item: September 30, December 31, Investments accounted for using the equity method (1) 1,575,832 1,493,791 Investments accounted for using the fair value option (2) 189,186 162,398 Total $ 1,765,018 $ 1,656,189 (1) Aggregate unfunded commitments were $1.44 billion at September 30, 2019 , compared to $1.22 billion at December 31, 2018 . (2) Aggregate unfunded commitments were $51.1 million at September 30, 2019 , compared to $117.5 million at December 31, 2018 . Net Investment Income The components of net investment income were derived from the following sources: September 30, 2019 2018 Three Months Ended Fixed maturities $ 126,889 $ 120,516 Term loans 24,236 21,903 Equity securities 3,992 3,165 Short-term investments 3,834 4,547 Other (1) 22,704 17,195 Gross investment income 181,655 167,326 Investment expenses (20,167 ) (23,302 ) Net investment income $ 161,488 $ 144,024 Nine Months Ended Fixed maturities $ 381,706 $ 343,513 Term loans 73,582 62,430 Equity securities 11,348 10,510 Short-term investments 11,872 13,799 Other (1) 62,423 52,210 Gross investment income 540,931 482,462 Investment expenses (67,456 ) (76,046 ) Net investment income $ 473,475 $ 406,416 (1) Includes income distributions from investment funds and other items. Net Realized Gains (Losses) Net realized gains (losses) were as follows, excluding net impairment losses recognized in earnings: September 30, 2019 2018 Three Months Ended Available for sale securities: Gross gains on investment sales $ 73,685 $ 10,990 Gross losses on investment sales (30,561 ) (34,879 ) Change in fair value of assets and liabilities accounted for using the fair value option: Fixed maturities (3,895 ) (6,604 ) Other investments (21,778 ) (7,950 ) Equity securities (1,231 ) 2,752 Short-term investments (1,941 ) (471 ) Equity securities, at fair value: Net realized gains (losses) on sales during the period 5,217 (2,012 ) Net unrealized gains (losses) on equity securities still held at reporting date (1,206 ) 10,798 Derivative instruments (1) 42,893 (17,556 ) Other (2) 1,335 (6,773 ) Net realized gains (losses) $ 62,518 $ (51,705 ) Nine Months Ended Available for sale securities: Gross gains on investment sales $ 192,140 $ 44,732 Gross losses on investment sales (77,498 ) (175,141 ) Change in fair value of assets and liabilities accounted for using the fair value option: Fixed maturities 38,682 (47,082 ) Other investments (37,363 ) (14,578 ) Equity securities 9,449 10,650 Short-term investments (2,613 ) (758 ) Equity securities, at fair value: Net realized gains (losses) on sales during the period 9,503 (13,298 ) Net unrealized gains (losses) on equity securities still held at reporting date 58,562 (4,063 ) Derivative instruments (1) 142,730 (23,665 ) Other (2) (8,703 ) (16,111 ) Net realized gains (losses) $ 324,889 $ (239,314 ) (1) See note 8 for information on the Company’s derivative instruments. (2) Includes the re-measurement of contingent consideration liability amounts. Equity in Net Income (Loss) of Investment Funds Accounted for Using the Equity Method The Company recorded $17.1 million of equity in net income related to investment funds accounted for using the equity method in the 2019 third quarter , compared to $16.0 million for the 2018 third quarter , and $96.5 million for the nine months ended September 30, 2019 , compared to $52.5 million for the 2018 period. In applying the equity method, investments are initially recorded at cost and are subsequently adjusted based on the Company’s proportionate share of the net income or loss of the funds (which include changes in the market value of the underlying securities in the funds). Such investments are generally recorded on a one to three month lag based on the availability of reports from the investment funds. Net Impairment Losses Recognized in Earnings The Company performs quarterly reviews of its available for sale investments in order to determine whether declines in fair value below the amortized cost basis were considered other-than-temporary in accordance with applicable guidance. The following table details the net impairment losses recognized in earnings by asset class: September 30, 2019 2018 Three Months Ended Fixed maturities: Mortgage backed securities $ (284 ) $ (73 ) Corporate bonds (666 ) (270 ) Non-U.S. government securities — (149 ) Asset backed securities (213 ) — Net impairment losses recognized in earnings $ (1,163 ) $ (492 ) Nine Months Ended Fixed maturities: Mortgage backed securities $ (839 ) $ (196 ) Corporate bonds (1,256 ) (631 ) Non-U.S. government securities — (149 ) Asset backed securities (426 ) (148 ) Net impairment losses recognized in earnings $ (2,521 ) $ (1,124 ) Net impairment losses recognized in earnings in the 2019 periods were primarily related to foreign currency fluctuations and other impairments on corporate bonds and other securities. The Company believes that the minimal amount of OTTI included in accumulated other comprehensive income at September 30, 2019 on the securities which were considered by the Company to be impaired was due to market and sector-related factors ( i.e. , not credit losses). At September 30, 2019 , the Company did not intend to sell these securities, or any other securities which were in an unrealized loss position, and determined that it is more likely than not that the Company will not be required to sell such securities before recovery of their cost basis. The following table provides a roll forward of the amount related to credit losses recognized in earnings for which a portion of an OTTI was recognized in accumulated other comprehensive income: September 30, 2019 2018 Three Months Ended Balance at start of period $ 346 $ 698 Credit loss impairments recognized on securities not previously impaired — — Credit loss impairments recognized on securities previously impaired — — Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security — — Reductions for securities sold during the period — (47 ) Balance at end of period $ 346 $ 651 Nine Months Ended Balance at start of year $ 637 $ 767 Credit loss impairments recognized on securities not previously impaired — — Credit loss impairments recognized on securities previously impaired — — Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security — — Reductions for securities sold during the period (291 ) (116 ) Balance at end of period $ 346 $ 651 Restricted Assets The Company is required to maintain assets on deposit, which primarily consist of fixed maturities, with various regulatory authorities to support its underwriting operations. The Company’s subsidiaries maintain assets in trust accounts as collateral for transactions with affiliated companies and also have investments in segregated portfolios primarily to provide collateral or guarantees for letters of credit to third parties. See note 16, “Commitments and Contingencies,” of the notes to consolidated financial statements in the Company’s 2018 Form 10-K. The following table details the value of the Company’s restricted assets: September 30, December 31, Assets used for collateral or guarantees: Affiliated transactions $ 4,629,369 $ 4,623,483 Third party agreements 2,605,587 2,181,682 Deposits with U.S. regulatory authorities 788,295 689,114 Deposits with non-U.S. regulatory authorities 71,800 59,624 Total restricted assets $ 8,095,051 $ 7,553,903 In addition, Watford maintains a secured credit facility to provide borrowing capacity for investment purposes and a total return swap agreement and maintains assets pledged as collateral for such purposes. The Company does not guarantee or provide credit support for Watford, and the Company’s financial exposure to Watford is limited to its investment in Watford’s senior notes, common and preferred shares and counterparty credit risk (mitigated by collateral) arising from reinsurance transactions. As of September 30, 2019 and December 31, 2018, Watford held $1.06 billion and $1.30 billion , respectively, in pledged assets to collateralize the credit facility mentioned above. Reconciliation of Cash and Restricted Cash The following table details reconciliation of cash and restricted cash within the Consolidated Balance Sheets: September 30, December 31, Cash $ 880,099 $ 646,556 Restricted cash (included in ‘other assets’) $ 82,376 $ 78,087 Cash and restricted cash $ 962,475 $ 724,643

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value	Fair Value Accounting guidance regarding fair value measurements addresses how companies should measure fair value when they are required to use a fair value measure for recognition or disclosure purposes under GAAP and provides a common definition of fair value to be used throughout GAAP. It defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly fashion between market participants at the measurement date. In addition, it establishes a three-level valuation hierarchy for the disclosure of fair value measurements. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. The level in the hierarchy within which a given fair value measurement falls is determined based on the lowest level input that is significant to the measurement (Level 1 being the highest priority and Level 3 being the lowest priority). The levels in the hierarchy are defined as follows: Level 1: Inputs to the valuation methodology are observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets Level 2: Inputs to the valuation methodology include quoted prices for similar assets and liabilities in active markets, and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument Level 3: Inputs to the valuation methodology are unobservable and significant to the fair value measurement Following is a description of the valuation methodologies used for securities measured at fair value, as well as the general classification of such securities pursuant to the valuation hierarchy. The Company reviews its securities measured at fair value and discusses the proper classification of such investments with investment advisers and others. The Company determines the existence of an active market based on its judgment as to whether transactions for the financial instrument occur in such market with sufficient frequency and volume to provide reliable pricing information. The independent pricing sources obtain market quotations and actual transaction prices for securities that have quoted prices in active markets. The Company uses quoted values and other data provided by nationally recognized independent pricing sources as inputs into its process for determining fair values of its fixed maturity investments. To validate the techniques or models used by pricing sources, the Company's review process includes, but is not limited to: (i) quantitative analysis ( e.g., comparing the quarterly return for each managed portfolio to its target benchmark, with significant differences identified and investigated); (ii) a review of the average number of prices obtained in the pricing process and the range of resulting fair values; (iii) initial and ongoing evaluation of methodologies used by outside parties to calculate fair value; (iv) a comparison of the fair value estimates to the Company’s knowledge of the current market; (v) a comparison of the pricing services' fair values to other pricing services' fair values for the same investments; and (vi) periodic back-testing, which includes randomly selecting purchased or sold securities and comparing the executed prices to the fair value estimates from the pricing service. A price source hierarchy was maintained in order to determine which price source would be used (i.e. , a price obtained from a pricing service with more seniority in the hierarchy will be used over a less senior one in all cases). The hierarchy prioritizes pricing services based on availability and reliability and assigns the highest priority to index providers. Based on the above review, the Company will challenge any prices for a security or portfolio which are considered not to be representative of fair value. The Company did not adjust any of the prices obtained from the independent pricing sources at September 30, 2019 . In certain circumstances, when fair values are unavailable from these independent pricing sources, quotes are obtained directly from broker-dealers who are active in the corresponding markets. Such quotes are subject to the validation procedures noted above. Of the $22.21 billion of financial assets and liabilities measured at fair value at September 30, 2019 , approximately $187.9 million , or 0.9% , were priced using non-binding broker-dealer quotes. Of the $20.41 billion of financial assets and liabilities measured at fair value at December 31, 2018 , approximately $217.9 million , or 1.1% , were priced using non-binding broker-dealer quotes. Fixed maturities The Company uses the market approach valuation technique to estimate the fair value of its fixed maturity securities, when possible. The market approach includes obtaining prices from independent pricing services, such as index providers and pricing vendors, as well as to a lesser extent quotes from broker-dealers. The independent pricing sources obtain market quotations and actual transaction prices for securities that have quoted prices in active markets. Each source has its own proprietary method for determining the fair value of securities that are not actively traded. In general, these methods involve the use of “matrix pricing” in which the independent pricing source uses observable market inputs including, but not limited to, investment yields, credit risks and spreads, benchmarking of like securities, broker-dealer quotes, reported trades and sector groupings to determine a reasonable fair value. The following describes the significant inputs generally used to determine the fair value of the Company’s fixed maturity securities by asset class: • U.S. government and government agencies — valuations provided by independent pricing services, with all prices provided through index providers and pricing vendors. The Company determined that all U.S. Treasuries would be classified as Level 1 securities due to observed levels of trading activity, the high number of strongly correlated pricing quotes received on U.S. Treasuries and other factors. The fair values of U.S. government agency securities are generally determined using the spread above the risk-free yield curve. As the yields for the risk-free yield curve and the spreads for these securities are observable market inputs, the fair values of U.S. government agency securities are classified within Level 2. • Corporate bonds — valuations provided by independent pricing services, substantially all through index providers and pricing vendors with a small amount through broker-dealers. The fair values of these securities are generally determined using the spread above the risk-free yield curve. These spreads are generally obtained from the new issue market, secondary trading and from broker-dealers who trade in the relevant security market. As the significant inputs used in the pricing process for corporate bonds are observable market inputs, the fair value of these securities are classified within Level 2. A small number of securities are included in Level 3 due to a low level of transparency on the inputs used in the pricing process. During the nine months ended September 30, 2019, the Company transferred $25.8 million of corporate bonds from Level 2 to Level 3 based on a review of the pricing of such securities, as described above. • Mortgage-backed securities — valuations provided by independent pricing services, substantially all through pricing vendors and index providers with a small amount through broker-dealers. The fair values of these securities are generally determined through the use of pricing models (including Option Adjusted Spread) which use spreads to determine the expected average life of the securities. These spreads are generally obtained from the new issue market, secondary trading and from broker-dealers who trade in the relevant security market. The pricing services also review prepayment speeds and other indicators, when applicable. As the significant inputs used in the pricing process for mortgage-backed securities are observable market inputs, the fair value of these securities are classified within Level 2. A small number of securities are included in Level 3 due to a low level of transparency on the inputs used in the pricing process. • Municipal bonds — valuations provided by independent pricing services, with all prices provided through index providers and pricing vendors. The fair values of these securities are generally determined using spreads obtained from broker-dealers who trade in the relevant security market, trade prices and the new issue market. As the significant inputs used in the pricing process for municipal bonds are observable market inputs, the fair value of these securities are classified within Level 2. • Commercial mortgage-backed securities — valuations provided by independent pricing services, substantially all through index providers and pricing vendors with a small amount through broker-dealers. The fair values of these securities are generally determined through the use of pricing models which use spreads to determine the appropriate average life of the securities. These spreads are generally obtained from the new issue market, secondary trading and from broker-dealers who trade in the relevant security market. The pricing services also review prepayment speeds and other indicators, when applicable. As the significant inputs used in the pricing process for commercial mortgage-backed securities are observable market inputs, the fair value of these securities are classified within Level 2. • Non-U.S. government securities — valuations provided by independent pricing services, with all prices provided through index providers and pricing vendors. The fair values of these securities are generally based on international indices or valuation models which include daily observed yield curves, cross-currency basis index spreads and country credit spreads. As the significant inputs used in the pricing process for non-U.S. government securities are observable market inputs, the fair value of these securities are classified within Level 2. • Asset-backed securities — valuations provided by independent pricing services, substantially all through index providers and pricing vendors with a small amount through broker-dealers. The fair values of these securities are generally determined through the use of pricing models (including Option Adjusted Spread) which use spreads to determine the appropriate average life of the securities. These spreads are generally obtained from the new issue market, secondary trading and from broker-dealers who trade in the relevant security market. The pricing services also review prepayment speeds and other indicators, when applicable. As the significant inputs used in the pricing process for asset-backed securities are observable market inputs, the fair value of these securities are classified within Level 2. During the nine months ended September 30, 2019, the Company transferred $5.5 million of asset-backed securities from Level 2 to Level 3 based on a review of the pricing of such securities, as described above. Equity securities The Company determined that exchange-traded equity securities would be included in Level 1 as their fair values are based on quoted market prices in active markets. Other equity securities are included in Level 2 of the valuation hierarchy. A small number of securities are included in Level 3 due to the lack of an available independent price source for such securities. As the significant inputs used to price these securities are unobservable, the fair value of such securities are classified as Level 3. During nine months ended September 30 2019, the Company transferred $107.4 million of equity securities from Level 2 to Level 3 based on a review of the pricing of such securities, as described above. Other investments The Company determined that exchange-traded investments in mutual funds would be included in Level 1 as their fair values are based on quoted market prices in active markets. Other investments also include term loan investments for which fair values are estimated by using quoted prices of term loan investments with similar characteristics, pricing models or matrix pricing. Such investments are generally classified within Level 2. The fair values for certain of the Company’s other investments are determined using net asset values as advised by external fund managers. The net asset value is based on the fund manager’s valuation of the underlying holdings in accordance with the fund’s governing documents. In accordance with applicable accounting guidance, certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. A small number of securities are included in Level 3 due to the lack of an available independent price source for such securities. During the nine months ended September 30, 2019, the Company transferred $31.6 million of other investments from Level 2 to Level 3 based on a review of the pricing of such securities, as described above. Derivative instruments The Company’s futures contracts, foreign currency forward contracts, interest rate swaps and other derivatives trade in the over-the-counter derivative market. The Company uses the market approach valuation technique to estimate the fair value for these derivatives based on significant observable market inputs from third party pricing vendors, non-binding broker-dealer quotes and/or recent trading activity. As the significant inputs used in the pricing process for these derivative instruments are observable market inputs, the fair value of these securities are classified within Level 2. Short-term investments The Company determined that certain of its short-term investments held in highly liquid money market-type funds, Treasury bills and commercial paper would be included in Level 1 as their fair values are based on quoted market prices in active markets. The fair values of other short-term investments are generally determined using the spread above the risk-free yield curve and are classified within Level 2. Contingent consideration liabilities Contingent consideration liabilities (included in ‘other liabilities’ in the consolidated balance sheets) include amounts related to the acquisition of CMG Mortgage Insurance Company and its affiliated mortgage insurance companies and other acquisitions. Such amounts are remeasured at fair value at each balance sheet date with changes in fair value recognized in ‘net realized gains (losses).’ To determine the fair value of contingent consideration liabilities, the Company estimates future payments using an income approach based on modeled inputs which include a weighted average cost of capital. The Company determined that contingent consideration liabilities would be included within Level 3. The following table presents the Company’s financial assets and liabilities measured at fair value by level at September 30, 2019 : Estimated Fair Value Measurements Using: Estimated Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets measured at fair value (1): Available for sale securities: Fixed maturities: Corporate bonds $ 6,269,993 $ — $ 6,261,248 $ 8,745 Mortgage backed securities 544,033 — 543,761 272 Municipal bonds 653,346 — 653,346 — Commercial mortgage backed securities 754,306 — 754,306 — U.S. government and government agencies 5,127,290 5,005,512 121,778 — Non-U.S. government securities 1,873,856 — 1,873,856 — Asset backed securities 1,657,494 — 1,652,045 5,449 Total 16,880,318 5,005,512 11,860,340 14,466 Short-term investments 751,989 720,518 31,471 — Equity securities, at fair value 561,105 514,380 11,402 35,323 Derivative instruments (4) 51,647 — 51,647 — Fair value option: Corporate bonds 619,779 — 597,000 22,779 Non-U.S. government bonds 61,755 — 61,755 — Mortgage backed securities 15,512 — 15,512 — Municipal bonds 1,140 — 1,140 — Asset backed securities 208,620 — 208,620 — U.S. government and government agencies 1,996 1,886 110 — Short-term investments 390,980 376,033 14,947 — Equity securities 98,340 41,333 735 56,272 Other investments 1,411,420 41,316 1,284,661 85,443 Other investments measured at net asset value (2) 1,028,700 Total 3,838,242 460,568 2,184,480 164,494 Total assets measured at fair value $ 22,083,301 $ 6,700,978 $ 14,139,340 $ 214,283 Liabilities measured at fair value: Contingent consideration liabilities $ (7,344 ) $ — $ — $ (7,344 ) Securities sold but not yet purchased (3) (65,736 ) — (65,736 ) — Derivative instruments (4) (53,740 ) — (53,740 ) — Total liabilities measured at fair value $ (126,820 ) $ — $ (119,476 ) $ (7,344 ) (1) In securities lending transactions, the Company receives collateral in excess of the fair value of the securities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See note 6 , “—Securities Lending Agreements.” (2) In accordance with applicable accounting guidance, certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. (3) Represents the Company’s obligations to deliver securities that it did not own at the time of sale. Such amounts are included in “other liabilities” on the Company’s consolidated balance sheets. (4) See note 8 . The following table presents the Company’s financial assets and liabilities measured at fair value by level at December 31, 2018 : Estimated Fair Value Measurements Using: Estimated Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets measured at fair value (1): Available for sale securities: Fixed maturities: Corporate bonds $ 5,537,548 $ — $ 5,529,407 $ 8,141 Mortgage backed securities 541,193 — 540,884 309 Municipal bonds 1,013,395 — 1,013,395 — Commercial mortgage backed securities 729,442 — 729,438 4 U.S. government and government agencies 3,758,698 3,657,181 101,517 — Non-U.S. government securities 1,771,338 — 1,771,338 — Asset backed securities 1,600,896 — 1,600,896 — Total 14,952,510 3,657,181 11,286,875 8,454 Equity securities 353,794 321,927 31,867 — Short-term investments 955,880 875,881 79,999 — Derivative instruments (4) 73,893 — 73,893 — Fair value option: Corporate bonds 852,585 — 846,827 5,758 Non-U.S. government bonds 79,066 — 79,066 — Mortgage backed securities 16,731 — 16,731 — Municipal bonds 7,144 — 7,144 — Asset backed securities 178,790 — 178,790 — U.S. government and government agencies 111,246 111,138 108 — Short-term investments 322,177 278,579 43,598 — Equity securities 103,893 48,827 55,066 — Other investments 1,254,220 39,107 1,152,408 62,705 Other investments measured at net asset value (2) 1,057,719 Total 3,983,571 477,651 2,379,738 68,463 Total assets measured at fair value $ 20,319,648 $ 5,332,640 $ 13,852,372 $ 76,917 Liabilities measured at fair value: Contingent consideration liabilities $ (66,665 ) $ — $ — $ (66,665 ) Securities sold but not yet purchased (3) (7,790 ) — (7,790 ) — Derivative instruments (4) (20,664 ) — (20,664 ) — Total liabilities measured at fair value $ (95,119 ) $ — $ (28,454 ) $ (66,665 ) (1) In securities lending transactions, the Company receives collateral in excess of the fair value of the securities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See note 6 , “—Securities Lending Agreements.” (2) In accordance with applicable accounting guidance, certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. (3) Represents the Company’s obligations to deliver securities that it did not own at the time of sale. Such amounts are included in “other liabilities” on the Company’s consolidated balance sheets. (4) See note 8 . The following table presents a reconciliation of the beginning and ending balances for all financial assets and liabilities measured at fair value on a recurring basis using Level 3 inputs: Assets Liabilities s Available For Sale Fair Value Option Fair Value Structured Securities (1) Corporate Corporate Other Investments Equity Securities Equity Securities Contingent Consideration Liabilities Three Months Ended September 30, 2019 Balance at beginning of period $ 290 $ 7,642 $ 26,103 $ 95,273 $ 56,145 $ 51,212 $ (7,825 ) Total gains or (losses) (realized/unrealized) Included in earnings (2) — — (1,227 ) (411 ) 127 (26 ) (79 ) Included in other comprehensive income — (301 ) — — — — — Purchases, issuances, sales and settlements Purchases — — — 3,713 — 12,119 — Issuances — — — — — — — Sales — — (2,097 ) (80 ) — (27,982 ) — Settlements (18 ) (456 ) — — — — 560 Transfers in and/or out of Level 3 5,449 1,860 — (13,052 ) — — — Balance at end of period $ 5,721 $ 8,745 $ 22,779 $ 85,443 $ 56,272 $ 35,323 $ (7,344 ) Three Months Ended September 30, 2018 Balance at beginning of period $ 376 $ 8,773 $ 11,335 $ 58,214 $ — $ — $ (63,930 ) Total gains or (losses) (realized/unrealized) Included in earnings (2) — (1 ) (503 ) (1,459 ) — — (1,711 ) Included in other comprehensive income 2 (32 ) — — — — — Purchases, issuances, sales and settlements Purchases — — — 6,250 — — — Issuances — — — — — — — Sales — — — (74 ) — — — Settlements (33 ) (456 ) (1,226 ) — — — — Transfers in and/or out of Level 3 — — — — — — — Balance at end of period $ 345 $ 8,284 $ 9,606 $ 62,931 $ — $ — $ (65,641 ) Nine Months Ended September 30, 2019 Balance at beginning of year $ 313 $ 8,141 $ 5,758 $ 62,705 $ — $ — $ (66,665 ) Total gains or (losses) (realized/unrealized) Included in earnings (2) 1,757 — (1,566 ) (11,727 ) 127 (26 ) (1,410 ) Included in other comprehensive income 5 (317 ) — — — — — Purchases, issuances, sales and settlements Purchases — 429 — 3,713 — 12,119 — Issuances — — — — — — (548 ) Sales (1,757 ) — (5,332 ) (228 ) — (27,982 ) — Settlements (46 ) (1,368 ) — (600 ) — — 61,279 Transfers in and/or out of Level 3 5,449 1,860 23,919 31,580 56,145 51,212 — Balance at end of period $ 5,721 $ 8,745 $ 22,779 $ 85,443 $ 56,272 $ 35,323 $ (7,344 ) Nine Months Ended September 30, 2018 Balance at beginning of year $ 5,927 $ 9,460 $ 12,217 $ 59,167 $ — $ — $ (60,996 ) Total gains or (losses) (realized/unrealized) Included in earnings (2) 4 (1 ) (1,115 ) (1,838 ) — — (4,645 ) Included in other comprehensive income (6 ) (200 ) — — — — — Purchases, issuances, sales and settlements Purchases — 393 — 6,250 — — — Issuances — — — — — — — Sales (5,003 ) — — (148 ) — — — Settlements (577 ) (1,368 ) (1,496 ) (500 ) — — — Transfers in and/or out of Level 3 — — — — — — — Balance at end of period $ 345 $ 8,284 $ 9,606 $ 62,931 $ — $ — $ (65,641 ) (1) Includes asset backed securities, mortgage backed securities and commercial mortgage backed securities. (2) Gains or losses were included in net realized gains (losses). Financial Instruments Disclosed, But Not Carried, At Fair Value The Company uses various financial instruments in the normal course of its business. The carrying values of cash, accrued investment income, receivable for securities sold, certain other assets, payable for securities purchased and certain other liabilities approximated their fair values at September 30, 2019 , due to their respective short maturities. As these financial instruments are not actively traded, their respective fair values are classified within Level 2. At September 30, 2019 , the Company’s senior notes were carried at their cost, net of debt issuance costs, of $1.87 billion and had a fair value of $2.35 billion . At December 31, 2018 , the Company’s senior notes were carried at their cost, net of debt issuance costs, of $1.73 billion and had a fair value of $1.88 billion

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments The Company’s investment strategy allows for the use of derivative instruments. The Company’s derivative instruments are recorded on its consolidated balance sheets at fair value. The Company utilizes exchange traded U.S. Treasury note, Eurodollar and other futures contracts and commodity futures to manage portfolio duration or replicate investment positions in its portfolios and the Company routinely utilizes foreign currency forward contracts, currency options, index futures contracts and other derivatives as part of its total return objective. In addition, certain of the Company’s investments are managed in portfolios which incorporate the use of foreign currency forward contracts which are intended to provide an economic hedge against foreign currency movements. In addition, the Company purchases to-be-announced mortgage backed securities (“TBAs”) as part of its investment strategy. TBAs represent commitments to purchase a future issuance of agency mortgage backed securities. For the period between purchase of a TBA and issuance of the underlying security, the Company’s position is accounted for as a derivative. The Company purchases TBAs in both long and short positions to enhance investment performance and as part of its overall investment strategy. The following table summarizes information on the fair values and notional values of the Company’s derivative instruments: Estimated Fair Value Asset Derivatives Liability Derivatives Notional Value (1) September 30, 2019 Futures contracts (2) $ 15,148 $ (20,515 ) $ 3,987,260 Foreign currency forward contracts (2) 5,316 (8,616 ) 965,348 TBAs (3) 54,961 — 53,229 Other (2) 31,183 (24,609 ) 3,983,466 Total $ 106,608 $ (53,740 ) December 31, 2018 Futures contracts (2) $ 51,800 $ (2,115 ) $ 3,153,518 Foreign currency forward contracts (2) 8,147 (7,796 ) 1,008,907 TBAs (3) 8,292 — 8,132 Other (2) 13,946 (10,753 ) 2,213,981 Total $ 82,185 $ (20,664 ) (1) Represents the absolute notional value of all outstanding contracts, consisting of long and short positions. (2) The fair value of asset derivatives are included in ‘other assets’ and the fair value of liability derivatives are included in ‘other liabilities.’ (3) The fair value of TBAs are included in ‘fixed maturities available for sale, at fair value.’ The Company did not hold any derivatives which were designated as hedging instruments at September 30, 2019 or December 31, 2018 . The Company’s derivative instruments can be traded under master netting agreements, which establish terms that apply to all derivative transactions with a counterparty. In the event of a bankruptcy or other stipulated event of default, such agreements provide that the non-defaulting party may elect to terminate all outstanding derivative transactions, in which case all individual derivative positions (loss or gain) with a counterparty are closed out and netted and replaced with a single amount, usually referred to as the termination amount, which is expressed in a single currency. The resulting single net amount, where positive, is payable to the party “in-the-money” regardless of whether or not it is the defaulting party, unless the parties have agreed that only the non-defaulting party is entitled to receive a termination payment where the net amount is positive and is in its favor. Contractual close-out netting reduces derivatives credit exposure from gross to net exposure. The remaining derivatives included in the table above were not subject to a master netting agreement. At September 30, 2019 , asset derivatives and liability derivatives of $105.5 million and $52.7 million , respectively, were subject to a master netting agreement, compared to $80.4 million and $18.9 million , respectively, at December 31, 2018 . The remaining derivatives included in the preceding table were not subject to a master netting agreement. Realized and unrealized contract gains and losses on the Company’s derivative instruments are reflected in ‘net realized gains (losses)’ in the consolidated statements of income, as summarized in the following table: Derivatives not designated as September 30, hedging instruments: 2019 2018 Three Months Ended Net realized gains (losses): Futures contracts $ 46,194 $ (15,399 ) Foreign currency forward contracts 2,044 (5,458 ) TBAs 269 (3 ) Other (5,614 ) 3,304 Total $ 42,893 $ (17,556 ) Nine Months Ended Net realized gains (losses): Futures contracts $ 140,503 $ (10,609 ) Foreign currency forward contracts (17,030 ) (13,074 ) TBAs 507 (100 ) Other 18,750 118 Total $ 142,730 $ (23,665 )

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Investment Commitments The Company’s investment commitments, which are primarily related to agreements entered into by the Company to invest in funds and separately managed accounts when called upon, were approximately $1.90 billion at September 30, 2019 , compared to $1.77 billion at December 31, 2018 . Interest Paid Interest paid on the Company’s senior notes and other borrowings were $68.6 million for the nine months ended September 30, 2019 , consistent with $67.6 million for the 2018 period. Letter of Credit and Revolving Credit Facilities In September 2019, Watford entered into an unsecured letter of credit agreement. Watford has access to a $100 million letter of credit facility expiring on September 20, 2020. The Company does not guarantee or provide credit support for Watford, and the Company’s financial exposure to Watford is limited to its investment in Watford’s senior notes, common and preferred shares and counterparty credit risk (mitigated by collateral) arising from the reinsurance transactions.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	Leases In the ordinary course of business, the Company renews and enters into new leases for office property and equipment. At the lease inception date, the Company determines whether a contract contains a lease and its classification as a finance or operating lease. Primarily all of the Company’s leases are classified as operating leases. The Company’s operating leases have remaining lease terms of up to 11 years , some of which include options to extend the lease term. The Company considers these options when determining the lease term and measuring its lease liability and right-of-use asset. In addition, the Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants. Short-term operating leases with an initial term of twelve months or less were excluded on the Company's consolidated balance sheet and represent an inconsequential amount of operating lease expense. As most leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of lease payments. Additional information regarding the Company’s operating leases is as follows: September 30, 2019 Three Months Ended Operating lease costs $ 7,751 Cash payments included in the measurement of lease liabilities reported in operating cash flows $ 8,031 Right-of-use assets obtained in exchange for new lease liabilities $ 2,897 Right-of-use assets (1) $ 131,424 Operating lease liability (1) $ 147,326 Weighted average discount rate 3.9 % Weighted average remaining lease term 6.3 years Nine Months Ended Operating lease costs $ 22,611 Cash payments included in the measurement of lease liabilities reported in operating cash flows $ 22,616 Right-of-use assets obtained in exchange for new lease liabilities $ 7,009 Right-of-use assets (1) $ 131,424 Operating lease liability (1) $ 147,326 Weighted average discount rate 3.9 % Weighted average remaining lease term 6.3 years (1) The right-of-use assets are included in ‘other assets’ while the operating lease liability is included in ‘other liabilities.’ The following table presents the contractual maturities of the Company's operating lease liabilities at September 30, 2019 : Years Ending December 31, 2019 (remainder) $ 1,693 2020 31,541 2021 30,392 2022 27,096 2023 22,290 2024 and thereafter 55,080 Total undiscounted lease liability $ 168,092 Less: present value adjustment (20,767 ) Operating lease liability $ 147,325 At December 31, 2018 , the future minimum rental commitments, exclusive of escalation clauses and maintenance costs and net of rental income, for all of the Company’s operating leases was as follows: 2019 $ 31,088 2020 30,491 2021 29,351 2022 26,068 2023 21,408 2024 and thereafter 54,745 Total $ 193,151

Variable Interest Entities and

Variable Interest Entities and Noncontrolling Interests	9 Months Ended
	Sep. 30, 2019
Noncontrolling Interest [Abstract]
Variable Interest Entity and Noncontrolling Interests	Variable Interest Entities and Noncontrolling Interests Watford In March 2014, the Company invested $100.0 million and acquired 2,500,000 common shares, approximately 11% of Watford’s outstanding common equity, and a warrant to purchase up to 975,503 additional common shares. The warrants expire on March 31, 2020. The exercise price of the warrants is determined on the date of exercise based on certain targeted returns for existing common shareholders. Watford’s common shares are listed on the Nasdaq Select Global Market under the ticker symbol “WTRE”. On July 2, 2019, Watford completed an offering of $175.0 million in aggregate principal amount of its 6.5% senior notes, due July 2, 2029 (“Watford Senior Notes”). Interest on the Watford Senior Notes will be paid semi-annually in arrears on each January 2 and July 2, commencing January 2, 2020. The $172.4 million net proceeds from the offering were used to redeem a portion of Watford’s outstanding preference shares (“Watford Preference Shares”). The Company purchased $35.0 million in aggregate principal amount of the Watford Senior Notes. Watford is considered a VIE and the Company concluded that it is the primary beneficiary of Watford. As such, the results of Watford are included in the Company’s consolidated financial statements. The Company does not guarantee or provide credit support for Watford, and the Company’s financial exposure to Watford is limited to its investment in Watford’s senior notes, common and preferred shares and counterparty credit risk (mitigated by collateral) arising from reinsurance transactions. The following table provides the carrying amount and balance sheet caption in which the assets and liabilities of Watford are reported: September 30, December 31, 2019 2018 Assets Investments accounted for using the fair value option $ 2,048,295 $ 2,312,003 Fixed maturities available for sale, at fair value 678,094 393,351 Equity securities, at fair value 43,488 32,206 Cash 80,390 63,529 Accrued investment income 18,277 19,461 Premiums receivable 302,265 227,301 Reinsurance recoverable on unpaid and paid losses and LAE 144,437 86,445 Ceded unearned premiums 129,909 61,587 Deferred acquisition costs 67,241 80,858 Receivable for securities sold 25,283 24,507 Goodwill and intangible assets 7,650 7,650 Other assets 66,165 63,959 Total assets of consolidated VIE $ 3,611,494 $ 3,372,857 Liabilities Reserve for losses and loss adjustment expenses $ 1,164,945 $ 1,032,760 Unearned premiums 454,148 390,114 Reinsurance balances payable 79,264 21,034 Revolving credit agreement borrowings 490,720 455,682 Senior notes 172,350 — Payable for securities purchased 40,586 60,142 Other liabilities (1) 196,431 302,524 Total liabilities of consolidated VIE $ 2,598,444 $ 2,262,256 Redeemable noncontrolling interests $ 52,281 $ 220,992 (1) Includes certain borrowings related to investing activities. For the nine months ended September 30, 2019 , Watford generated $177.2 million of cash provided by operating activities, $181.2 million of cash used for investing activities and $22.2 million of cash provided by financing activities, compared to $174.3 million of cash provided by operating activities, $208.3 million of cash used for investing activities and $24.2 million of cash used for financing activities for the nine months ended September 30, 2018 . Non-redeemable noncontrolling interests The Company accounts for the portion of Watford’s common equity attributable to third party investors in the shareholders’ equity section of its consolidated balance sheets. The noncontrolling ownership in Watford’s common shares was approximately 89% at September 30, 2019 . The portion of Watford’s income or loss attributable to third party investors is recorded in the consolidated statements of income in ‘net (income) loss attributable to noncontrolling interests.’ The following table sets forth activity in the non-redeemable noncontrolling interests: September 30, 2019 2018 Three Months Ended Balance, beginning of period $ 855,347 $ 861,153 Additional paid in capital attributable to noncontrolling interests 205 — Amounts attributable to noncontrolling interests 136 16,759 Other comprehensive income (loss) attributable to noncontrolling interests (764 ) (1,158 ) Balance, end of period $ 854,924 $ 876,754 Nine Months Ended Balance, beginning of year $ 791,560 $ 843,411 Additional paid in capital attributable to noncontrolling interests 2,279 — Amounts attributable to noncontrolling interests 54,819 36,251 Other comprehensive income (loss) attributable to noncontrolling interests 6,266 (2,908 ) Balance, end of period $ 854,924 $ 876,754 Redeemable noncontrolling interests The Company accounts for redeemable noncontrolling interests in the mezzanine section of its consolidated balance sheets in accordance with applicable accounting guidance. Such redeemable noncontrolling interests relate to the Watford Preference Shares issued in late March 2014 with a par value of $0.01 per share and a liquidation preference of $25.00 per share. The Watford Preference Shares were issued at a discounted amount of $24.50 per share. Preferred dividends, including the accretion of the discount and issuance costs, are included in ‘net (income) loss attributable to noncontrolling interests’ in the Company’s consolidated statements of income. On August 1, 2019, Watford redeemed 6,919,998 of its 9,065,200 issued and outstanding Watford Preference Shares. The Watford Preference Shares were redeemed at a total redemption price of $25.19748 per share, inclusive of all declared and unpaid dividends, with accumulation of any undeclared dividends on or after June 30, 2019. In addition, the Company received $11.5 million pursuant to the redemption of Watford Preference Shares. The following table sets forth activity in the redeemable non-controlling interests: September 30, 2019 2018 Three Months Ended Balance, beginning of period $ 206,475 $ 206,105 Redemption of noncontrolling interests (157,709 ) — Accretion of preference share issuance costs 23 94 Balance, end of period $ 48,789 $ 206,199 Nine Months Ended Balance, beginning of year $ 206,292 $ 205,922 Redemption of noncontrolling interests (157,709 ) — Accretion of preference share issuance costs 206 277 Balance, end of period $ 48,789 $ 206,199 The portion of Watford’s income or loss attributable to third party investors, recorded in the Company’s consolidated statements of income in ‘net (income) loss attributable to noncontrolling interests,’ are summarized in the table below: September 30, 2019 2018 Three Months Ended Amounts attributable to non-redeemable noncontrolling interests $ (136 ) $ (16,759 ) Dividends attributable to redeemable noncontrolling interests (6,600 ) (4,599 ) Net (income) loss attributable to noncontrolling interests $ (6,736 ) $ (21,358 ) Nine Months Ended Amounts attributable to non-redeemable noncontrolling interests $ (54,819 ) $ (36,251 ) Dividends attributable to redeemable noncontrolling interests (15,778 ) (13,769 ) Net (income) loss attributable to noncontrolling interests $ (70,597 ) $ (50,020 ) Bellemeade Re The Company has entered into various aggregate excess of loss mortgage reinsurance agreements with various special purpose reinsurance companies domiciled in Bermuda (the “Bellemeade Agreements”). At the time the Bellemeade Agreements were entered into, the applicability of the accounting guidance that addresses VIEs was evaluated. As a result of the evaluation of the Bellemeade Agreements, the Company concluded that these entities are VIEs. However, given that the ceding insurers do not have the unilateral power to direct those activities that are significant to their economic performance, the Company does not consolidate such entities in its consolidated financial statements. The following table presents the total assets of the Bellemeade entities, as well as the Company’s maximum exposure to loss associated with these VIEs, calculated as the maximum historical observable spread between the one month LIBOR, the basis for the contractual payments to bond holders, and short term invested trust asset yields. Maximum Exposure to Loss Bellemeade Entities (Issue Date) Total VIE Assets On-Balance Sheet (Asset) Liability Off-Balance Sheet Total Sep 30, 2019 Bellemeade 2015-1 Ltd. (Jul-15) $ 6,046 $ — $ 2 $ 2 Bellemeade 2017-1 Ltd. (Oct-17) 249,737 (345 ) 3,526 3,181 Bellemeade 2018-1 Ltd. (Apr-18) 362,603 (1,351 ) 7,035 5,684 Bellemeade 2018-2 Ltd. (Aug-18) 507,534 (829 ) 3,395 2,566 Bellemeade 2018-3 Ltd. (Oct-18) 488,430 (916 ) 4,600 3,684 Bellemeade 2019-1 Ltd. (Mar-19) 293,595 (210 ) 4,533 4,323 Bellemeade 2019-2 Ltd. (Apr-19) 621,022 (367 ) 15,161 14,794 Bellemeade 2019-3 Ltd. (July-19) 700,920 (468 ) 11,888 11,420 Total $ 3,229,887 $ (4,486 ) $ 50,140 $ 45,654 Dec 31, 2018 Bellemeade 2015-1 Ltd. (Jul-15) $ 43,246 $ 112 $ 498 $ 610 Bellemeade 2017-1 Ltd. (Oct-17) 304,373 165 1,312 1,477 Bellemeade 2018-1 Ltd. (Apr-18) 374,460 132 3,539 3,671 Bellemeade 2018-2 Ltd. (Aug-18) 653,278 874 4,005 4,879 Bellemeade 2018-3 Ltd. (Oct-18) 506,110 469 1,836 2,305 Total $ 1,881,467 $ 1,752 $ 11,190 $ 12,942 See note 16 .

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2019
Comprehensive Income Note Disclosure [Abstract]
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) The following tables present details about amounts reclassified from accumulated other comprehensive income and the tax effects allocated to each component of other comprehensive income (loss): Amounts Reclassified from AOCI Consolidated Statement of Income Three Months Ended Nine Months Ended Details About Line Item That Includes September 30, September 30, AOCI Components Reclassification 2019 2018 2019 2018 Unrealized appreciation on available-for-sale investments Net realized gains (losses) $ 43,124 $ (23,888 ) $ 114,642 $ (130,409 ) Other-than-temporary impairment losses (1,163 ) (492 ) (2,521 ) (1,124 ) Total before tax 41,961 (24,380 ) 112,121 (131,533 ) Income tax (expense) benefit (3,218 ) 1,177 (7,812 ) 9,226 Net of tax $ 38,743 $ (23,203 ) $ 104,309 $ (122,307 ) Before Tax Amount Tax Expense (Benefit) Net of Tax Amount Three Months Ended September 30, 2019 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ 70,449 $ 11,159 $ 59,290 Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) — — — Less reclassification of net realized gains (losses) included in net income 41,961 3,218 38,743 Foreign currency translation adjustments (16,507 ) (83 ) (16,424 ) Other comprehensive income (loss) $ 11,981 $ 7,858 $ 4,123 Three Months Ended September 30, 2018 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ (57,812 ) $ (4,504 ) $ (53,308 ) Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) — — — Less reclassification of net realized gains (losses) included in net income (24,380 ) (1,177 ) (23,203 ) Foreign currency translation adjustments 2,167 104 2,063 Other comprehensive income (loss) $ (31,265 ) $ (3,223 ) $ (28,042 ) Nine Months Ended September 30, 2019 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ 573,513 $ 65,863 $ 507,650 Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) — — — Less reclassification of net realized gains (losses) included in net income 112,121 7,812 104,309 Foreign currency translation adjustments (6,454 ) 187 (6,641 ) Other comprehensive income (loss) $ 454,938 $ 58,238 $ 396,700 Nine Months Ended September 30, 2018 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ (335,789 ) $ (30,533 ) $ (305,256 ) Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) — — — Less reclassification of net realized gains (losses) included in net income (131,533 ) (9,226 ) (122,307 ) Foreign currency translation adjustments (9,102 ) 148 (9,250 ) Other comprehensive income (loss) $ (213,358 ) $ (21,159 ) $ (192,199 )

Guarantor Financial Information

Guarantor Financial Information	9 Months Ended
	Sep. 30, 2019
Condensed Financial Information Disclosure [Abstract]
Guarantor Financial Information	Guarantor Financial Information The following tables present condensed financial information for Arch Capital, Arch Capital Group (U.S.) Inc. (“Arch-U.S.”), a 100% owned subsidiary of Arch Capital, and Arch Capital’s other subsidiaries. The senior notes of Arch-U.S. due November 1, 2043 are fully and unconditionally guaranteed by Arch Capital. September 30, 2019 Condensed Consolidating Balance Sheet Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Assets Total investments $ 41 $ 918,720 $ 22,737,556 $ (38,982 ) $ 23,617,335 Cash 12,696 72,727 794,676 — 880,099 Investments in subsidiaries 11,454,186 4,189,656 — (15,643,842 ) — Due from subsidiaries and affiliates 106 2 1,899,559 (1,899,667 ) — Premiums receivable — — 2,446,539 (828,353 ) 1,618,186 Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses — — 8,490,131 (5,321,936 ) 3,168,195 Contractholder receivables — — 2,094,683 — 2,094,683 Ceded unearned premiums — — 2,149,492 (981,234 ) 1,168,258 Deferred acquisition costs — — 674,559 (52,531 ) 622,028 Goodwill and intangible assets — — 624,500 — 624,500 Other assets 21,336 25,586 1,875,817 (143,420 ) 1,779,319 Total assets $ 11,488,365 $ 5,206,691 $ 43,787,512 $ (24,909,965 ) $ 35,572,603 Liabilities Reserve for losses and loss adjustment expenses $ — $ — $ 17,486,844 $ (5,097,460 ) $ 12,389,384 Unearned premiums — — 5,224,606 (981,234 ) 4,243,372 Reinsurance balances payable — — 1,430,244 (828,353 ) 601,891 Contractholder payables — — 2,094,683 — 2,094,683 Collateral held for insured obligations — — 205,449 205,449 Senior notes 297,228 494,803 1,114,355 (35,000 ) 1,871,386 Revolving credit agreement borrowings — — 490,720 — 490,720 Due to subsidiaries and affiliates 8 542,103 1,357,556 (1,899,667 ) — Other liabilities 33,033 55,585 1,946,208 (420,917 ) 1,613,909 Total liabilities 330,269 1,092,491 31,350,665 (9,262,631 ) 23,510,794 Redeemable noncontrolling interests — — 52,281 (3,492 ) 48,789 Shareholders’ Equity Total shareholders’ equity available to Arch 11,158,096 4,114,200 11,529,642 (15,643,842 ) 11,158,096 Non-redeemable noncontrolling interests — — 854,924 — 854,924 Total shareholders’ equity 11,158,096 4,114,200 12,384,566 (15,643,842 ) 12,013,020 Total liabilities, noncontrolling interests and shareholders’ equity $ 11,488,365 $ 5,206,691 $ 43,787,512 $ (24,909,965 ) $ 35,572,603 December 31, 2018 Condensed Consolidating Balance Sheet Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Assets Total investments $ 104 $ 452,674 $ 21,307,206 $ (14,700 ) $ 21,745,284 Cash 6,125 5,940 634,491 — 646,556 Investments in subsidiaries 9,735,256 3,999,243 — (13,734,499 ) — Due from subsidiaries and affiliates 9 2 1,802,686 (1,802,697 ) — Premiums receivable — — 1,834,389 (535,239 ) 1,299,150 Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses — — 8,618,660 (5,699,288 ) 2,919,372 Contractholder receivables — — 2,079,111 — 2,079,111 Ceded unearned premiums — — 1,730,262 (754,793 ) 975,469 Deferred acquisition costs — — 618,535 (48,961 ) 569,574 Goodwill and intangible assets — — 634,920 — 634,920 Other assets 12,588 80,949 1,466,438 (211,082 ) 1,348,893 Total assets $ 9,754,082 $ 4,538,808 $ 40,726,698 $ (22,801,259 ) $ 32,218,329 Liabilities Reserve for losses and loss adjustment expenses $ — $ — $ 17,345,142 $ (5,491,845 ) $ 11,853,297 Unearned premiums — — 4,508,429 (754,793 ) 3,753,636 Reinsurance balances payable — — 928,346 (535,239 ) 393,107 Contractholder payables — — 2,079,111 — 2,079,111 Collateral held for insured obligations — — 236,630 — 236,630 Senior notes 297,150 494,723 941,655 — 1,733,528 Revolving credit agreement borrowings — — 455,682 — 455,682 Due to subsidiaries and affiliates — 536,805 1,265,892 (1,802,697 ) — Other liabilities 17,105 26,270 1,699,768 (467,484 ) 1,275,659 Total liabilities 314,255 1,057,798 29,460,655 (9,052,058 ) 21,780,650 Redeemable noncontrolling interests — — 220,992 (14,700 ) 206,292 Shareholders’ Equity Total shareholders’ equity available to Arch 9,439,827 3,481,010 10,253,491 (13,734,501 ) 9,439,827 Non-redeemable noncontrolling interests — — 791,560 — 791,560 Total shareholders’ equity 9,439,827 3,481,010 11,045,051 (13,734,501 ) 10,231,387 Total liabilities, noncontrolling interests and shareholders’ equity $ 9,754,082 $ 4,538,808 $ 40,726,698 $ (22,801,259 ) $ 32,218,329 Three Months Ended September 30, 2019 Condensed Consolidating Statement of Income and Comprehensive Income Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Revenues Net premiums earned $ — $ — $ 1,438,023 $ — $ 1,438,023 Net investment income 81 2,899 181,621 (23,113 ) 161,488 Net realized gains (losses) — 1,880 66,683 (6,045 ) 62,518 Net impairment losses recognized in earnings — — (1,163 ) — (1,163 ) Other underwriting income — — 3,326 — 3,326 Equity in net income (loss) of investment funds accounted for using the equity method — 600 16,530 — 17,130 Other income (loss) (153 ) — 1,491 — 1,338 Total revenues (72 ) 5,379 1,706,511 (29,158 ) 1,682,660 Expenses Losses and loss adjustment expenses — — 802,455 — 802,455 Acquisition expenses — — 211,120 — 211,120 Other operating expenses — — 196,512 — 196,512 Corporate expenses 15,066 1,631 364 — 17,061 Amortization of intangible assets — — 20,003 — 20,003 Interest expense 5,539 12,019 36,712 (22,942 ) 31,328 Net foreign exchange (gains) losses 1 — (25,405 ) (7,720 ) (33,124 ) Total expenses 20,606 13,650 1,241,761 (30,662 ) 1,245,355 Income (loss) before income taxes (20,678 ) (8,271 ) 464,750 1,504 437,305 Income tax (expense) benefit — 1,647 (39,763 ) — (38,116 ) Income (loss) before equity in net income of subsidiaries (20,678 ) (6,624 ) 424,987 1,504 399,189 Equity in net income of subsidiaries 413,131 124,814 — (537,945 ) — Net income 392,453 118,190 424,987 (536,441 ) 399,189 Net (income) loss attributable to noncontrolling interests — — (6,906 ) 170 (6,736 ) Net income available to Arch 392,453 118,190 418,081 (536,271 ) 392,453 Preferred dividends (10,403 ) — — — (10,403 ) Net income available to Arch common shareholders $ 382,050 $ 118,190 $ 418,081 $ (536,271 ) $ 382,050 Comprehensive income available to Arch $ 397,340 $ 138,832 $ 427,238 $ (566,070 ) $ 397,340 Three Months Ended September 30, 2018 Condensed Consolidating Statement of Income and Comprehensive Income Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Revenues Net premiums earned $ — $ — $ 1,290,878 $ — $ 1,290,878 Net investment income 2 1,202 165,289 (22,469 ) 144,024 Net realized gains (losses) — (64 ) (51,641 ) — (51,705 ) Net impairment losses recognized in earnings — — (492 ) — (492 ) Other underwriting income — — 5,823 — 5,823 Equity in net income (loss) of investment funds accounted for using the equity method — — 15,982 — 15,982 Other income (loss) (195 ) — (531 ) — (726 ) Total revenues (193 ) 1,138 1,425,308 (22,469 ) 1,403,784 Expenses Losses and loss adjustment expenses — — 699,420 — 699,420 Acquisition expenses — — 201,602 — 201,602 Other operating expenses — — 161,098 — 161,098 Corporate expenses 15,170 446 (1,281 ) — 14,335 Amortization of intangible assets — — 26,315 — 26,315 Interest expense 5,536 12,075 34,276 (22,157 ) 29,730 Net foreign exchange (gains) losses — — (10,426 ) (412 ) (10,838 ) Total expenses 20,706 12,521 1,111,004 (22,569 ) 1,121,662 Income (loss) before income taxes (20,899 ) (11,383 ) 314,304 100 282,122 Income tax (expense) benefit — 2,276 (35,632 ) — (33,356 ) Income (loss) before equity in net income of subsidiaries (20,899 ) (9,107 ) 278,672 100 248,766 Equity in net income of subsidiaries 248,307 92,906 — (341,213 ) — Net income (loss) 227,408 83,799 278,672 (341,113 ) 248,766 Net (income) loss attributable to noncontrolling interests — — (21,669 ) 311 (21,358 ) Net income (loss) available to Arch 227,408 83,799 257,003 (340,802 ) 227,408 Preferred dividends (10,402 ) — — — (10,402 ) Net income (loss) available to Arch common shareholders $ 217,006 $ 83,799 $ 257,003 $ (340,802 ) $ 217,006 Comprehensive income available to Arch $ 200,524 $ 77,389 $ 230,565 $ (307,954 ) $ 200,524 Nine Months Ended September 30, 2019 Condensed Consolidating Statement of Income and Comprehensive Income Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Revenues Net premiums earned $ — $ — $ 4,270,616 $ — $ 4,270,616 Net investment income 165 9,425 532,031 (68,146 ) 473,475 Net realized gains (losses) — 16,223 320,356 (11,690 ) 324,889 Net impairment losses recognized in earnings — — (2,521 ) — (2,521 ) Other underwriting income — — 18,104 — 18,104 Equity in net income (loss) of investment funds accounted for using the equity method — 536 95,997 — 96,533 Other income (loss) (634 ) — 4,184 — 3,550 Total revenues (469 ) 26,184 5,238,767 (79,836 ) 5,184,646 Expenses Losses and loss adjustment expenses — — 2,288,530 — 2,288,530 Acquisition expenses — — 619,057 — 619,057 Other operating expenses — — 596,589 — 596,589 Corporate expenses 46,666 5,912 696 — 53,274 Amortization of intangible assets — — 60,214 — 60,214 Interest expense 16,615 35,966 104,430 (67,338 ) 89,673 Net foreign exchange (gains) losses 3 — (26,715 ) (4,985 ) (31,697 ) Total expenses 63,284 41,878 3,642,801 (72,323 ) 3,675,640 Income (loss) before income taxes (63,753 ) (15,694 ) 1,595,966 (7,513 ) 1,509,006 Income tax (expense) benefit — 3,491 (131,965 ) — (128,474 ) Income (loss) before equity in net income of subsidiaries (63,753 ) (12,203 ) 1,464,001 (7,513 ) 1,380,532 Equity in net income of subsidiaries 1,373,688 410,115 — (1,783,803 ) — Net income 1,309,935 397,912 1,464,001 (1,791,316 ) 1,380,532 Net (income) loss attributable to noncontrolling interests — — (71,405 ) 808 (70,597 ) Net income available to Arch 1,309,935 397,912 1,392,596 (1,790,508 ) 1,309,935 Preferred dividends (31,209 ) — — — (31,209 ) Net income available to Arch common shareholders $ 1,278,726 $ 397,912 $ 1,392,596 $ (1,790,508 ) $ 1,278,726 Comprehensive income available to Arch $ 1,700,369 $ 608,108 $ 1,779,463 $ (2,387,571 ) $ 1,700,369 Nine Months Ended September 30, 2018 Condensed Consolidating Statement of Income and Comprehensive Income Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Revenues Net premiums earned $ — $ — $ 3,862,540 $ — $ 3,862,540 Net investment income 37 2,020 471,588 (67,229 ) 406,416 Net realized gains (losses) 29 (71 ) (239,272 ) — (239,314 ) Net impairment losses recognized in earnings — — (1,124 ) — (1,124 ) Other underwriting income — — 15,046 — 15,046 Equity in net income (loss) of investment funds accounted for using the equity method — — 52,523 — 52,523 Other income (loss) 2,066 — 395 — 2,461 Total revenues 2,132 1,949 4,161,696 (67,229 ) 4,098,548 Expenses Losses and loss adjustment expenses — — 2,062,433 — 2,062,433 Acquisition expenses — — 595,816 — 595,816 Other operating expenses — — 512,294 — 512,294 Corporate expenses 47,981 1,205 2,973 — 52,159 Amortization of intangible assets — — 79,523 — 79,523 Interest expense 16,609 36,014 104,359 (66,272 ) 90,710 Net foreign exchange (gains) losses 29 — (37,347 ) (7,505 ) (44,823 ) Total expenses 64,619 37,219 3,320,051 (73,777 ) 3,348,112 Income (loss) before income taxes (62,487 ) (35,270 ) 841,645 6,548 750,436 Income tax (expense) benefit — 7,704 (86,643 ) — (78,939 ) Income (loss) before equity in net income of subsidiaries (62,487 ) (27,566 ) 755,002 6,548 671,497 Equity in net income of subsidiaries 683,964 266,053 — (950,017 ) — Net income 621,477 238,487 755,002 (943,469 ) 671,497 Net (income) loss attributable to noncontrolling interests — — (50,976 ) 956 (50,020 ) Net income available to Arch 621,477 238,487 704,026 (942,513 ) 621,477 Preferred dividends (31,242 ) — — — (31,242 ) Loss on redemption of preferred shares (2,710 ) — — — (2,710 ) Net income available to Arch common shareholders $ 587,525 $ 238,487 $ 704,026 $ (942,513 ) $ 587,525 Comprehensive income available to Arch $ 432,186 $ 153,992 $ 522,448 $ (676,440 ) $ 432,186 Nine Months Ended September 30, 2019 Condensed Consolidating Statement of Cash Flows Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Operating Activities Net Cash Provided By (Used For) Operating Activities $ 42,221 $ 525,712 $ 1,554,406 $ (579,200 ) $ 1,543,139 Investing Activities Purchases of fixed maturity investments — (868,773 ) (23,313,996 ) 172,146 (24,010,623 ) Purchases of equity securities — (74,502 ) (520,292 ) 70,743 (524,051 ) Purchases of other investments — (28,557 ) (986,368 ) — (1,014,925 ) Proceeds from the sales of fixed maturity investments — 482,804 22,373,404 (148,354 ) 22,707,854 Proceeds from the sales of equity securities — 7,441 434,432 (70,743 ) 371,130 Proceeds from the sales, redemptions and maturities of other investments — 1,057 826,460 — 827,517 Proceeds from redemptions and maturities of fixed maturity investments — — 394,719 — 394,719 Net settlements of derivative instruments — — 92,423 — 92,423 Net (purchases) sales of short-term investments 63 31,605 97,410 — 129,078 Change in cash collateral related to securities lending — — 6,990 — 6,990 Contributions to subsidiaries (2,121 ) — (70,125 ) 72,246 — Issuance of intercompany loans — — (53,828 ) 53,828 — Purchases of fixed assets (32 ) — (27,603 ) — (27,635 ) Other — (10,000 ) (192,953 ) — (202,953 ) Net Cash Provided By (Used For) Investing Activities (2,090 ) (458,925 ) (939,327 ) 149,866 (1,250,476 ) Financing Activities Purchases of common shares under share repurchase program (2,871 ) — — — (2,871 ) Proceeds from common shares issued, net 518 — 72,246 (72,246 ) 518 Proceeds from intercompany borrowings — — 53,828 (53,828 ) — Proceeds from borrowings — — 235,083 (35,000 ) 200,083 Repayments of intercompany borrowings — — — — — Repayments of borrowings — — (27,538 ) — (27,538 ) Change in cash collateral related to securities lending — — (6,990 ) — (6,990 ) Change in third party investment in redeemable noncontrolling interests — — (173,082 ) 11,208 (161,874 ) Dividends paid to redeemable noncontrolling interests — — (12,217 ) 809 (11,408 ) Dividends paid to parent (1) — — (578,391 ) 578,391 — Other — — (5,207 ) — (5,207 ) Preferred dividends paid (31,209 ) — — — (31,209 ) Net Cash Provided By (Used For) Financing Activities (33,562 ) — (442,268 ) 429,334 (46,496 ) Effects of exchange rates changes on foreign currency cash and restricted cash — — (8,335 ) — (8,335 ) Increase (decrease) in cash and restricted cash 6,569 66,787 164,476 — 237,832 Cash and restricted cash, beginning of year 6,159 5,940 712,544 — 724,643 Cash and restricted cash, end of period $ 12,728 $ 72,727 $ 877,020 $ — $ 962,475 (1) Dividends received by parent are included in net cash provided by (used for) operating activities. Nine Months Ended September 30, 2018 Condensed Consolidating Statement of Cash Flows Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Operating Activities Net Cash Provided By (Used For) Operating Activities $ 222,097 $ 176,851 $ 1,622,248 $ (900,209 ) $ 1,120,987 Investing Activities Purchases of fixed maturity investments — (214,449 ) (25,229,184 ) 605,716 (24,837,917 ) Purchases of equity securities — — (819,342 ) — (819,342 ) Purchases of other investments — — (1,543,332 ) — (1,543,332 ) Proceeds from the sales of fixed maturity investments — 111,533 23,804,386 (605,716 ) 23,310,203 Proceeds from the sales of equity securities — — 866,919 — 866,919 Proceeds from the sales, redemptions and maturities of other investments — — 1,178,035 — 1,178,035 Proceeds from redemptions and maturities of fixed maturity investments — — 724,021 — 724,021 Net settlements of derivative instruments — — 765 — 765 Net (purchases) sales of short-term investments 96,397 (49,031 ) 506,949 — 554,315 Change in cash collateral related to securities lending — — 137,073 — 137,073 Contributions to subsidiaries — (2,500 ) (29,646 ) 32,146 — Purchases of fixed assets (71 ) — (18,979 ) — (19,050 ) Other (4 ) — 58,231 — 58,227 Net Cash Provided By (Used For) Investing Activities 96,322 (154,447 ) (364,104 ) 32,146 (390,083 ) Financing Activities Redemption of preferred shares (92,555 ) — — — (92,555 ) Purchases of common shares under share repurchase program (184,529 ) — — — (184,529 ) Proceeds from common shares issued, net (12,029 ) — 32,146 (32,146 ) (12,029 ) Proceeds from borrowings — — 167,259 — 167,259 Repayments of borrowings — — (427,000 ) — (427,000 ) Change in cash collateral related to securities lending — — (137,073 ) — (137,073 ) Dividends paid to redeemable noncontrolling interests — — (14,447 ) 956 (13,491 ) Dividends paid to parent (1) — — (899,253 ) 899,253 — Other — — (6,084 ) — (6,084 ) Preferred dividends paid (31,242 ) — — — (31,242 ) Net Cash Provided By (Used For) Financing Activities (320,355 ) — (1,284,452 ) 868,063 (736,744 ) Effects of exchange rates changes on foreign currency cash and restricted cash — — (11,625 ) — (11,625 ) Increase (decrease) in cash and restricted cash (1,936 ) 22,404 (37,933 ) — (17,465 ) Cash and restricted cash, beginning of year 10,048 30,380 686,856 — 727,284 Cash and restricted cash, end of period $ 8,112 $ 52,784 $ 648,923 $ — $ 709,819 (1) Dividends received by parent are included in net cash provided by (used for) operating activities.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company’s income tax provision on income before income taxes resulted in an expense of 8.5% for the nine months ended September 30, 2019 , compared to an expense of 10.5% for the 2018 period. The Company’s effective tax rate, which is based upon the expected annual effective tax rate, may fluctuate from period to period based on the relative mix of income or loss reported by jurisdiction and the varying tax rates in each jurisdiction. For interim reporting purposes, the Company has calculated its annual effective tax rate for the full year of 2019 by treating excess tax benefits in the U.S. that arise from the accounting for stock based compensation as a discrete item. As such, this amount is not included when projecting the Company’s full year annual effective tax rate but rather is accounted for at the U.S. Federal statutory rate of 21% after applying the projected full year annual effective tax rate to actual nine months results before the discrete item. The impact of the discrete item resulted in a benefit of 0.4% for the nine months ended September 30, 2019 . The Company had a net deferred tax liability of $55.9 million at September 30, 2019 , compared to a net deferred tax asset of $22.5 million at December 31, 2018 . The change is primarily a result of the appreciation of the Company’s fixed maturities from December 31, 2018 to September 30, 2019. In addition, the Company paid $47.1 million and recovered $34.0 million of income taxes for the nine months ended September 30, 2019 and 2018 , respectively.

Legal Proceedings

Legal Proceedings	9 Months Ended
	Sep. 30, 2019
Disclosure Legal Proceedings [Abstract]
Legal Proceedings	Legal Proceedings The Company, in common with the insurance industry in general, is subject to litigation and arbitration in the normal course of its business. As of September 30, 2019 , the Company was not a party to any litigation or arbitration which is expected by management to have a material adverse effect on the Company’s results of operations and financial condition and liquidity.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Bellemeade Re 2019-4 Ltd. In October 2019, the Company’s first-lien U.S. mortgage insurance subsidiaries entered into an aggregate excess of loss reinsurance agreement with Bellemeade Re 2019-4 Ltd. (“Bellemeade 2019-4”), a special purpose reinsurance company domiciled in Bermuda. The Bellemeade 2019-4 agreement provides for up to $577.3 million of aggregate excess of loss reinsurance coverage at inception in excess of $162.4 million of aggregate losses for new delinquencies on a portfolio of in-force policies issued in the first half of 2019. The coverage amount decreases over a ten -year period as the underlying covered mortgages amortize. Bellemeade 2019-4 financed the coverage through the issuance of mortgage insurance-linked notes in an aggregate amount of approximately $577.3 million to unrelated investors (the “Notes”). The maturity date of the Notes is October 25, 2029. The Notes will be redeemed prior to maturity upon the occurrence of a mandatory termination event or if the ceding insurers trigger a termination of the reinsurance agreement following the occurrence of an optional termination event. All of the proceeds paid to Bellemeade 2019-4 from the sale of the Notes were deposited into a reinsurance trust as security for Bellemeade 2019-4’s obligations. At all times, funds in the reinsurance trust account are required to be invested in high credit quality money market funds. Catastrophic Events In the 2019 fourth quarter, Typhoon Hagibis, the ongoing wildfires in California and other catastrophic events may have an impact on the Company’s financial results. It is too early to reasonably estimate losses for these events given the significant uncertainties and the early stage of the damage assessment process, among other factors. Share Repurchases At September 30, 2019, approximately $160.9 million of share repurchases were available under Arch Capital’s share repurchase program. From October 1 through October 31, 2019, the Company did not repurchase any common shares. On November 8, 2019, the board of directors of ACGL increased the aggregate purchase amount authorized under the share repurchase program to $1.0 billion . Repurchases under this authorization may be effected from time to time in open market or privately negotiated transactions through December 31, 2021. The timing and amount of the repurchase transactions under this authorization will depend on a variety of factors, including market conditions and corporate and regulatory considerations.

Basis of Presentation and Rec_2

Basis of Presentation and Recent Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of accounting	The interim consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). All significant intercompany transactions and balances have been eliminated in consolidation.
Use of estimates	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ materially from those estimates and assumptions. In the opinion of management, the accompanying unaudited interim consolidated financial statements reflect all adjustments (consisting of normally recurring accruals) necessary for a fair statement of results on an interim basis. The results of any interim period are not necessarily indicative of the results for a full year or any future periods.
Recent accounting pronouncements	Recently Issued Accounting Standards Adopted The Company adopted ASU 2016-02, “Leases (Topic 842)”, which provides a new comprehensive model for lease accounting. Topic 842 requires a lessee to recognize a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term. The Company adopted the modified retrospective approach of this standard, that resulted in the recognition of a right-of-use asset of $147.9 million as part of other assets and a lease liability of $163.6 million as part of other liabilities in the consolidated balance sheet as of January 1, 2019. The Company de-recognized the liability for deferred rent that was required under the previous guidance. In addition, the Company adopted ASU 2018-11, “Leases: Targeted Improvements (Topic 842),” which provides an additional (optional) transition method to adopt the new lease standard. The Company adopted the alternative transition method and elected to utilize a cumulative-effect adjustment to the opening balance of the retained earnings for the year of adoption. As such, the Company’s reporting for the comparative periods prior to the adoption continue to be presented in the financial statements in accordance with previous lease accounting guidance. The Company also adopted the practical expedients as a package which allows the Company to not reassess (1) whether any expired or existing contracts are or contain leases (2) the lease classification for any expired or existing leases (3) initial direct costs for any existing leases and (4) to account for the lease and non lease components as a single lease component. In addition to electing the practical expedients as a package, the Company elected to include hindsight to determine the lease term of existing leases, and made an accounting policy election to not apply the recognition requirements to short-term leases (lease term of less than twelve months). The cumulative effect adjustment to the opening balance of retained earnings was zero . The adoption of the updated guidance did not have a material effect on the Company’s results of operations or liquidity. The Company adopted ASU 2018-07 “Improvements to Nonemployee Share-Based Payment Accounting,” which was issued in June 2018 to simplify the accounting for share-based payments granted to nonemployees for goods and services. Under this ASU, most of the guidance on such payments to nonemployees would be aligned with the requirements for share-based payments granted to employees. The ASU is effective for reporting periods beginning after December 15, 2018. This guidance and the adoption of this provision did not have a material effect on the Company's financial position, results of operations or cash flows. The Company adopted ASU 2018-02 “Income Statement-Reporting Comprehensive Income (Topic 220) - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income,” which was issued in February 2018 to allow the reclassification of the stranded tax effects in accumulated other comprehensive income (“AOCI”) resulting from the Tax Cuts and Jobs Act of 2017 (“Tax Cuts Act”). Current guidance requires the effect of a change in tax laws or rates on deferred tax balances to be reported in income from continuing operations in the accounting period that includes the period of enactment, even if the related income tax effects were originally charged or credited directly to AOCI. The amount of the reclassification would include the effect of the change in the U.S. federal corporate income tax rate on the gross deferred tax amounts and related valuation allowances, if any, at the date of the enactment of the Tax Cuts Act related to items in AOCI. The updated guidance is effective for reporting periods beginning after December 15, 2018 and is to be applied retrospectively to each period in which the effect of the Tax Cuts Act related to items remaining in AOCI are recognized or at the beginning of the period of adoption. The adoption of this ASU did not have a material effect on the Company’s results of operations, financial position or liquidity. The Company adopted ASU 2017-08 “Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20), Premium Amortization on Purchased Callable Debt Securities,” which was issued in March, 2017. This ASU shortens the amortization period for certain callable debt securities held at a premium and requires the premium to be amortized to the earliest call date. However, the new guidance does not require an accounting change for securities held at a discount whose discount continues to be amortized to maturity. The standard is effective for financial statements issued for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. The adoption of the guidance requires a modified retrospective approach with a cumulative-effect adjustment to retained earnings. The adoption of this ASU did not have a material effect on the Company’s consolidated financial statements. Recently Issued Accounting Standards Not Yet Adopted For information regarding additional accounting standards that the Company has not yet adopted, see note 3(q), “Significant Accounting Policies—Recent Accounting Pronouncements,” of the notes to consolidated financial statements in the Company’s 2018 Form 10-K.

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted earnings per common share	The following table sets forth the computation of basic and diluted earnings per common share: Three Months Ended Nine Months Ended September 30, September 30, 2019 2018 2019 2018 Numerator: Net income $ 399,189 $ 248,766 $ 1,380,532 $ 671,497 Amounts attributable to noncontrolling interests (6,736 ) (21,358 ) (70,597 ) (50,020 ) Net income available to Arch 392,453 227,408 1,309,935 621,477 Preferred dividends (10,403 ) (10,402 ) (31,209 ) (31,242 ) Loss on redemption of preferred shares — — — (2,710 ) Net income available to Arch common shareholders $ 382,050 $ 217,006 $ 1,278,726 $ 587,525 Denominator: Weighted average common shares outstanding 402,564,121 402,939,092 401,419,153 400,649,105 Series D preferred shares (1) — — — 4,427,123 Weighted average common shares and common share equivalents outstanding — basic 402,564,121 402,939,092 401,419,153 405,076,228 Effect of dilutive common share equivalents: Nonvested restricted shares 1,895,972 1,619,286 1,637,015 1,568,044 Stock options (2) 8,720,108 7,162,836 7,751,234 7,348,920 Weighted average common shares and common share equivalents outstanding — diluted 413,180,201 411,721,214 410,807,402 413,993,192 Earnings per common share: Basic $ 0.95 $ 0.54 $ 3.19 $ 1.45 Diluted $ 0.92 $ 0.53 $ 3.11 $ 1.42 (1) Such shares are convertible non-voting common equivalent preferred shares issued in connection with the UGC acquisition. See note 2 . (2) Certain stock options were not included in the computation of diluted earnings per share where the exercise price of the stock options exceeded the average market price and would have been anti-dilutive or where, when applying the treasury stock method to in-the-money options, the sum of the proceeds, including unrecognized compensation, exceeded the average market price and would have been anti-dilutive. For the 2019 third quarter and 2018 third quarter , the number of stock options excluded were 37,394 and 4,396,352 , respectively. For the nine months ended September 30, 2019 and 2018 period, the number of stock options excluded were 2,198,115 and 5,481,584 , respectively.

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Analysis of underwriting income or loss by segment and reconciliation to net income available to common shareholders	The following tables summarize the Company’s underwriting income or loss by segment, together with a reconciliation of underwriting income or loss to net income available to Arch common shareholders: Three Months Ended September 30, 2019 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 1,005,874 $ 662,572 $ 375,092 $ 2,043,292 $ 249,960 $ 2,181,121 Premiums ceded (302,034 ) (226,096 ) (57,703 ) (585,587 ) (94,208 ) (567,664 ) Net premiums written 703,840 436,476 317,389 1,457,705 155,752 1,613,457 Change in unearned premiums (98,504 ) (72,621 ) 25,611 (145,514 ) (29,920 ) (175,434 ) Net premiums earned 605,336 363,855 343,000 1,312,191 125,832 1,438,023 Other underwriting income (loss) — (1,208 ) 3,955 2,747 579 3,326 Losses and loss adjustment expenses (422,782 ) (270,379 ) (13,080 ) (706,241 ) (96,214 ) (802,455 ) Acquisition expenses (91,259 ) (62,393 ) (34,396 ) (188,048 ) (23,072 ) (211,120 ) Other operating expenses (115,408 ) (32,533 ) (37,003 ) (184,944 ) (11,568 ) (196,512 ) Underwriting income (loss) $ (24,113 ) $ (2,658 ) $ 262,476 235,705 (4,443 ) 231,262 Net investment income 126,874 34,614 161,488 Net realized gains (losses) 81,177 (18,659 ) 62,518 Net impairment losses recognized in earnings (1,163 ) — (1,163 ) Equity in net income (loss) of investment funds accounted for using the equity method 17,130 — 17,130 Other income (loss) 1,338 — 1,338 Corporate expenses (2) (15,066 ) — (15,066 ) Transaction costs and other (2) (1,995 ) — (1,995 ) Amortization of intangible assets (20,003 ) — (20,003 ) Interest expense (23,237 ) (8,091 ) (31,328 ) Net foreign exchange gains (losses) 29,794 3,330 33,124 Income before income taxes 430,554 6,751 437,305 Income tax expense (38,116 ) — (38,116 ) Net income 392,438 6,751 399,189 Dividends attributable to redeemable noncontrolling interests — (6,600 ) (6,600 ) Amounts attributable to nonredeemable noncontrolling interests — (136 ) (136 ) Net income available to Arch 392,438 15 392,453 Preferred dividends (10,403 ) — (10,403 ) Net income available to Arch common shareholders $ 382,035 $ 15 $ 382,050 Underwriting Ratios Loss ratio 69.8 % 74.3 % 3.8 % 53.8 % 76.5 % 55.8 % Acquisition expense ratio 15.1 % 17.1 % 10.0 % 14.3 % 18.3 % 14.7 % Other operating expense ratio 19.1 % 8.9 % 10.8 % 14.1 % 9.2 % 13.7 % Combined ratio 104.0 % 100.3 % 24.6 % 82.2 % 104.0 % 84.2 % Goodwill and intangible assets $ 158,990 $ — $ 457,860 $ 616,850 $ 7,650 $ 624,500 (1) Certain amounts included in the gross premiums written of each segment are related to intersegment transactions. Accordingly, the sum of gross premiums written for each segment does not agree to the total gross premiums written as shown in the table above due to the elimination of intersegment transactions in the total. (2) Certain expenses have been excluded from ‘corporate expenses’ and reflected in ‘transaction costs and other.’ Three Months Ended September 30, 2018 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 836,820 $ 435,396 $ 350,559 $ 1,622,532 $ 185,033 $ 1,731,328 Premiums ceded (259,968 ) (123,705 ) (57,226 ) (440,656 ) (33,356 ) (397,775 ) Net premiums written 576,852 311,691 293,333 1,181,876 151,677 1,333,553 Change in unearned premiums (15,794 ) (18,418 ) 7,591 (26,621 ) (16,054 ) (42,675 ) Net premiums earned 561,058 293,273 300,924 1,155,255 135,623 1,290,878 Other underwriting income (loss) — 1,387 3,733 5,120 703 5,823 Losses and loss adjustment expenses (409,435 ) (183,413 ) (9,615 ) (602,463 ) (96,957 ) (699,420 ) Acquisition expenses (88,255 ) (50,367 ) (33,361 ) (171,983 ) (29,619 ) (201,602 ) Other operating expenses (90,081 ) (29,936 ) (31,122 ) (151,139 ) (9,959 ) (161,098 ) Underwriting income (loss) $ (26,713 ) $ 30,944 $ 230,559 234,790 (209 ) 234,581 Net investment income 114,328 29,696 144,024 Net realized gains (losses) (47,010 ) (4,695 ) (51,705 ) Net impairment losses recognized in earnings (492 ) — (492 ) Equity in net income (loss) of investment funds accounted for using the equity method 15,982 — 15,982 Other income (loss) (726 ) — (726 ) Corporate expenses (2) (13,244 ) — (13,244 ) Transaction costs and other (2) (1,091 ) — (1,091 ) Amortization of intangible assets (26,315 ) — (26,315 ) Interest expense (24,666 ) (5,064 ) (29,730 ) Net foreign exchange gains (losses) 7,130 3,708 10,838 Income before income taxes 258,686 23,436 282,122 Income tax expense (33,356 ) — (33,356 ) Net income 225,330 23,436 248,766 Dividends attributable to redeemable noncontrolling interests — (4,599 ) (4,599 ) Amounts attributable to nonredeemable noncontrolling interests — (16,759 ) (16,759 ) Net income available to Arch 225,330 2,078 227,408 Preferred dividends (10,402 ) — (10,402 ) Net income available to Arch common shareholders $ 214,928 $ 2,078 $ 217,006 Underwriting Ratios Loss ratio 73.0 % 62.5 % 3.2 % 52.1 % 71.5 % 54.2 % Acquisition expense ratio 15.7 % 17.2 % 11.1 % 14.9 % 21.8 % 15.6 % Other operating expense ratio 16.1 % 10.2 % 10.3 % 13.1 % 7.3 % 12.5 % Combined ratio 104.8 % 89.9 % 24.6 % 80.1 % 100.6 % 82.3 % Goodwill and intangible assets $ 20,141 $ — $ 538,871 $ 559,012 $ 7,650 $ 566,662 (1) Certain amounts included in the gross premiums written of each segment are related to intersegment transactions. Accordingly, the sum of gross premiums written for each segment does not agree to the total gross premiums written as shown in the table above due to the elimination of intersegment transactions in the total. (2) Certain expenses have been excluded from ‘corporate expenses’ and reflected in ‘transaction costs and other.’ Nine Months Ended September 30, 2019 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 2,867,753 $ 1,890,974 $ 1,095,607 $ 5,853,574 $ 598,627 $ 6,196,809 Premiums ceded (914,751 ) (627,120 ) (149,358 ) (1,690,469 ) (178,118 ) (1,613,195 ) Net premiums written 1,953,002 1,263,854 946,249 4,163,105 420,509 4,583,614 Change in unearned premiums (201,719 ) (186,450 ) 72,436 (315,733 ) 2,735 (312,998 ) Net premiums earned 1,751,283 1,077,404 1,018,685 3,847,372 423,244 4,270,616 Other underwriting income (loss) — 4,393 11,867 16,260 1,844 18,104 Losses and loss adjustment expenses (1,168,677 ) (751,147 ) (50,226 ) (1,970,050 ) (318,480 ) (2,288,530 ) Acquisition expenses (265,177 ) (173,504 ) (98,722 ) (537,403 ) (81,654 ) (619,057 ) Other operating expenses (338,327 ) (102,197 ) (116,697 ) (557,221 ) (39,368 ) (596,589 ) Underwriting income (loss) $ (20,898 ) $ 54,949 $ 764,907 798,958 (14,414 ) 784,544 Net investment income 371,161 102,314 473,475 Net realized gains (losses) 318,722 6,167 324,889 Net impairment losses recognized in earnings (2,521 ) — (2,521 ) Equity in net income (loss) of investment funds accounted for using the equity method 96,533 — 96,533 Other income (loss) 3,550 — 3,550 Corporate expenses (2) (47,911 ) — (47,911 ) Transaction costs and other (2) (5,363 ) — (5,363 ) Amortization of intangible assets (60,214 ) — (60,214 ) Interest expense (70,094 ) (19,579 ) (89,673 ) Net foreign exchange gains (losses) 28,779 2,918 31,697 Income before income taxes 1,431,600 77,406 1,509,006 Income tax expense (128,454 ) (20 ) (128,474 ) Net income 1,303,146 77,386 1,380,532 Dividends attributable to redeemable noncontrolling interests — (15,778 ) (15,778 ) Amounts attributable to nonredeemable noncontrolling interests — (54,819 ) (54,819 ) Net income available to Arch 1,303,146 6,789 1,309,935 Preferred dividends (31,209 ) — (31,209 ) Net income available to Arch common shareholders $ 1,271,937 $ 6,789 $ 1,278,726 Underwriting Ratios Loss ratio 66.7 % 69.7 % 4.9 % 51.2 % 75.2 % 53.6 % Acquisition expense ratio 15.1 % 16.1 % 9.7 % 14.0 % 19.3 % 14.5 % Other operating expense ratio 19.3 % 9.5 % 11.5 % 14.5 % 9.3 % 14.0 % Combined ratio 101.1 % 95.3 % 26.1 % 79.7 % 103.8 % 82.1 % (1) Certain amounts included in the gross premiums written of each segment are related to intersegment transactions. Accordingly, the sum of gross premiums written for each segment does not agree to the total gross premiums written as shown in the table above due to the elimination of intersegment transactions in the total. (2) Certain expenses have been excluded from ‘corporate expenses’ and reflected in ‘transaction costs and other.’ Nine Months Ended September 30, 2018 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 2,429,570 $ 1,503,206 $ 1,002,727 $ 4,935,339 $ 574,078 $ 5,266,086 Premiums ceded (752,413 ) (455,682 ) (154,230 ) (1,362,161 ) (102,263 ) (1,221,093 ) Net premiums written 1,677,157 1,047,524 848,497 3,573,178 471,815 4,044,993 Change in unearned premiums (30,913 ) (134,761 ) 23,147 (142,527 ) (39,926 ) (182,453 ) Net premiums earned 1,646,244 912,763 871,644 3,430,651 431,889 3,862,540 Other underwriting income (loss) — 2,490 10,464 12,954 2,092 15,046 Losses and loss adjustment expenses (1,120,630 ) (555,044 ) (74,672 ) (1,750,346 ) (312,087 ) (2,062,433 ) Acquisition expenses (264,094 ) (148,828 ) (87,665 ) (500,587 ) (95,229 ) (595,816 ) Other operating expenses (274,735 ) (101,185 ) (108,622 ) (484,542 ) (27,752 ) (512,294 ) Underwriting income (loss) $ (13,215 ) $ 110,196 $ 611,149 708,130 (1,087 ) 707,043 Net investment income 322,332 84,084 406,416 Net realized gains (losses) (218,414 ) (20,900 ) (239,314 ) Net impairment losses recognized in earnings (1,124 ) — (1,124 ) Equity in net income (loss) of investment funds accounted for using the equity method 52,523 — 52,523 Other income (loss) 2,461 — 2,461 Corporate expenses (2) (43,330 ) — (43,330 ) Transaction costs and other (2) (8,829 ) — (8,829 ) Amortization of intangible assets (79,523 ) — (79,523 ) Interest expense (76,631 ) (14,079 ) (90,710 ) Net foreign exchange gains (losses) 38,302 6,521 44,823 Income before income taxes 695,897 54,539 750,436 Income tax expense (78,912 ) (27 ) (78,939 ) Net income 616,985 54,512 671,497 Dividends attributable to redeemable noncontrolling interests — (13,769 ) (13,769 ) Amounts attributable to nonredeemable noncontrolling interests — (36,251 ) (36,251 ) Net income available to Arch 616,985 4,492 621,477 Preferred dividends (31,242 ) — (31,242 ) Loss on redemption of preferred shares (2,710 ) — (2,710 ) Net income available to Arch common shareholders $ 583,033 $ 4,492 $ 587,525 Underwriting Ratios Loss ratio 68.1 % 60.8 % 8.6 % 51.0 % 72.3 % 53.4 % Acquisition expense ratio 16.0 % 16.3 % 10.1 % 14.6 % 22.0 % 15.4 % Other operating expense ratio 16.7 % 11.1 % 12.5 % 14.1 % 6.4 % 13.3 % Combined ratio 100.8 % 88.2 % 31.2 % 79.7 % 100.7 % 82.1 % (1) Certain amounts included in the gross premiums written of each segment are related to intersegment transactions. Accordingly, the sum of gross premiums written for each segment does not agree to the total gross premiums written as shown in the table above due to the elimination of intersegment transactions in the total. (2)

Reserve for Losses and Loss A_2

Reserve for Losses and Loss Adjustment Expenses (Tables)	9 Months Ended
	Sep. 30, 2019
Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract]
Analysis of losses and loss adjustment expenses and reconciliation of beginning and ending reserve balances	The following table represents an analysis of losses and loss adjustment expenses and a reconciliation of the beginning and ending reserve for losses and loss adjustment expenses: Three Months Ended Nine Months Ended September 30, September 30, 2019 2018 2019 2018 Reserve for losses and loss adjustment expenses at beginning of period $ 12,230,316 $ 11,424,337 $ 11,853,297 $ 11,383,792 Unpaid losses and loss adjustment expenses recoverable 3,024,797 2,651,749 2,814,291 2,464,910 Net reserve for losses and loss adjustment expenses at beginning of period 9,205,519 8,772,588 9,039,006 8,918,882 Net incurred losses and loss adjustment expenses relating to losses occurring in: Current year 855,352 779,043 2,419,044 2,257,670 Prior years (52,897 ) (79,623 ) (130,514 ) (195,237 ) Total net incurred losses and loss adjustment expenses 802,455 699,420 2,288,530 2,062,433 Retroactive reinsurance transactions (1) — — (225,500 ) (420,404 ) Net foreign exchange (gains) losses (73,200 ) (33,783 ) (74,981 ) (110,061 ) Net paid losses and loss adjustment expenses relating to losses occurring in: Current year (175,611 ) (149,999 ) (301,099 ) (245,021 ) Prior years (399,948 ) (396,695 ) (1,366,741 ) (1,314,298 ) Total net paid losses and loss adjustment expenses (575,559 ) (546,694 ) (1,667,840 ) (1,559,319 ) Net reserve for losses and loss adjustment expenses at end of period 9,359,215 8,891,531 9,359,215 8,891,531 Unpaid losses and loss adjustment expenses recoverable 3,030,169 2,662,790 3,030,169 2,662,790 Reserve for losses and loss adjustment expenses at end of period $ 12,389,384 $ 11,554,321 $ 12,389,384 $ 11,554,321 (1) During the 2019 first quarter and 2018 second quarter, a subsidiary of the Company entered into two separate retroactive reinsurance transactions with third party reinsurers to reinsure run-off liabilities associated with certain U.S. insurance exposures.

Investment Information (Tables)

Investment Information (Tables)	9 Months Ended
	Sep. 30, 2019
Disclosure Investment Information [Abstract]
Summary of fair value and cost or amortized cost of available for sale securities	The following table summarizes the fair value and cost or amortized cost of the Company’s securities classified as available for sale: Estimated Fair Value Gross Unrealized Gains Gross Unrealized Losses Cost or Amortized Cost OTTI Unrealized Losses (2) September 30, 2019 Fixed maturities (1): Corporate bonds $ 6,269,993 $ 198,742 $ (18,420 ) $ 6,089,671 $ — Mortgage backed securities 544,033 11,185 (918 ) 533,766 (6 ) Municipal bonds 653,346 27,095 (379 ) 626,630 — Commercial mortgage backed securities 754,306 27,523 (158 ) 726,941 — U.S. government and government agencies 5,127,290 67,957 (6,671 ) 5,066,004 — Non-U.S. government securities 1,873,856 48,212 (52,767 ) 1,878,411 — Asset backed securities 1,657,494 29,838 (5,931 ) 1,633,587 — Total 16,880,318 410,552 (85,244 ) 16,555,010 (6 ) Short-term investments 751,989 227 (445 ) 752,207 — Total $ 17,632,307 $ 410,779 $ (85,689 ) $ 17,307,217 $ (6 ) December 31, 2018 Fixed maturities (1): Corporate bonds $ 5,537,548 $ 14,476 $ (105,428 ) $ 5,628,500 $ (69 ) Mortgage backed securities 541,193 3,991 (3,216 ) 540,418 (6 ) Municipal bonds 1,013,395 5,380 (11,891 ) 1,019,906 — Commercial mortgage backed securities 729,442 2,650 (10,751 ) 737,543 — U.S. government and government agencies 3,758,698 27,189 (8,474 ) 3,739,983 — Non-U.S. government securities 1,771,338 14,477 (50,948 ) 1,807,809 — Asset backed securities 1,600,896 8,060 (14,798 ) 1,607,634 — Total 14,952,510 76,223 (205,506 ) 15,081,793 (75 ) Short-term investments 955,880 36 (394 ) 956,238 — Total $ 15,908,390 $ 76,259 $ (205,900 ) $ 16,038,031 $ (75 ) (1) In securities lending transactions, the Company receives collateral in excess of the fair value of the fixed maturities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See “—Securities Lending Agreements.” (2) Represents the total other-than-temporary impairments (“OTTI”) recognized in accumulated other comprehensive income (“AOCI”). It does not include the change in fair value subsequent to the impairment measurement date. At September 30, 2019 the net unrealized loss related to securities for which a non-credit OTTI was recognized in AOCI was $0.01 million , compared to net unrealized loss of $0.04 million at December 31, 2018
Summary of available for sale securities in a continual unrealized loss position	The following table summarizes, for all available for sale securities in an unrealized loss position, the fair value and gross unrealized loss by length of time the security has been in a continual unrealized loss position: Less than 12 Months 12 Months or More Total Estimated Gross Unrealized Losses Estimated Gross Unrealized Losses Estimated Gross Unrealized Losses September 30, 2019 Fixed maturities (1): Corporate bonds $ 538,471 $ (11,128 ) $ 113,987 $ (7,292 ) $ 652,458 $ (18,420 ) Mortgage backed securities 97,288 (905 ) 200 (13 ) 97,488 (918 ) Municipal bonds 43,627 (379 ) — — 43,627 (379 ) Commercial mortgage backed securities 47,219 (151 ) 1,872 (7 ) 49,091 (158 ) U.S. government and government agencies 1,592,232 (6,531 ) 47,416 (140 ) 1,639,648 (6,671 ) Non-U.S. government securities 1,214,128 (51,742 ) 47,576 (1,025 ) 1,261,704 (52,767 ) Asset backed securities 375,936 (4,600 ) 48,743 (1,331 ) 424,679 (5,931 ) Total 3,908,901 (75,436 ) 259,794 (9,808 ) 4,168,695 (85,244 ) Short-term investments 43,007 (445 ) — — 43,007 (445 ) Total $ 3,951,908 $ (75,881 ) $ 259,794 $ (9,808 ) $ 4,211,702 $ (85,689 ) December 31, 2018 Fixed maturities (1): Corporate bonds $ 2,983,195 $ (68,910 ) $ 1,234,865 $ (36,518 ) $ 4,218,060 $ (105,428 ) Mortgage backed securities 84,296 (695 ) 109,009 (2,521 ) 193,305 (3,216 ) Municipal bonds 233,081 (2,074 ) 408,155 (9,817 ) 641,236 (11,891 ) Commercial mortgage backed securities 223,341 (2,831 ) 193,956 (7,920 ) 417,297 (10,751 ) U.S. government and government agencies 635,049 (1,354 ) 391,102 (7,120 ) 1,026,151 (8,474 ) Non-U.S. government securities 1,028,340 (35,524 ) 389,671 (15,424 ) 1,418,011 (50,948 ) Asset backed securities 533,592 (8,832 ) 368,095 (5,966 ) 901,687 (14,798 ) Total 5,720,894 (120,220 ) 3,094,853 (85,286 ) 8,815,747 (205,506 ) Short-term investments 122,878 (394 ) — — 122,878 (394 ) Total $ 5,843,772 $ (120,614 ) $ 3,094,853 $ (85,286 ) $ 8,938,625 $ (205,900 ) (1) In securities lending transactions, the Company receives collateral in excess of the fair value of the fixed maturities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See “—Securities Lending Agreements.”
Contractual maturities of the Company's fixed maturities and fixed maturities pledged under securities lending arrangements	The contractual maturities of the Company’s fixed maturities are shown in the following table. Expected maturities, which are management’s best estimates, will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. September 30, 2019 December 31, 2018 Maturity Estimated Fair Value Amortized Cost Estimated Amortized Cost Due in one year or less $ 545,056 $ 538,903 $ 276,682 $ 279,135 Due after one year through five years 10,096,867 9,971,896 8,666,297 8,738,944 Due after five years through 10 years 3,075,318 2,952,478 2,919,232 2,951,582 Due after 10 years 207,244 197,439 218,768 226,537 13,924,485 13,660,716 12,080,979 12,196,198 Mortgage backed securities 544,033 533,766 541,193 540,418 Commercial mortgage backed securities 754,306 726,941 729,442 737,543 Asset backed securities 1,657,494 1,633,587 1,600,896 1,607,634 Total (1) $ 16,880,318 $ 16,555,010 $ 14,952,510 $ 15,081,793 (1) In securities lending transactions, the Company receives collateral in excess of the fair value of the securities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See “—Securities Lending Agreements.”
Securities lending transactions accounted for as secured borrowings, by significant investment category	The Company’s securities lending transactions were accounted for as secured borrowings with significant investment categories as follows: Remaining Contractual Maturity of the Agreements Overnight and Continuous Less than 30 Days 30-90 Days 90 Days or More Total September 30, 2019 U.S. government and government agencies $ 257,979 $ — $ 156,541 $ — $ 414,520 Corporate bonds 4,820 — — — 4,820 Equity securities 10,915 — — — 10,915 Total $ 273,714 $ — $ 156,541 $ — $ 430,255 Gross amount of recognized liabilities for securities lending in offsetting disclosure in note 8 $ — Amounts related to securities lending not included in offsetting disclosure in note 8 $ 430,255 December 31, 2018 U.S. government and government agencies $ 219,276 $ — $ 32,583 $ — $ 251,859 Corporate bonds 7,129 — — — 7,129 Equity securities 15,137 — — — 15,137 Total $ 241,542 $ — $ 32,583 $ — $ 274,125 Gross amount of recognized liabilities for securities lending in offsetting disclosure in note 8 $ — Amounts related to securities lending not included in offsetting disclosure in note 8 $ 274,125
Summary of other investments	The following table summarizes the Company’s other investments which are included in investments accounted for using the fair value option, by strategy: September 30, December 31, Term loan investments (par value: $1,434,328 and $1,369,216) $ 1,330,886 $ 1,282,287 Lending 624,699 524,112 Credit related funds 165,444 202,123 Energy 113,791 117,509 Investment grade fixed income 83,649 101,902 Infrastructure 49,602 45,371 Private equity 54,609 24,383 Real estate 17,440 14,252 Total $ 2,440,120 $ 2,311,939
Summary of investments accounted for using equity method	The following table summarizes the Company’s investments accounted for using the equity method, by strategy: September 30, December 31, Credit related funds $ 428,353 $ 429,402 Equities 284,465 375,273 Real estate 265,502 232,647 Lending 200,112 125,041 Private equity 141,343 114,019 Infrastructure 149,005 113,748 Energy 107,052 103,661 Total $ 1,575,832 $ 1,493,791
Summary of assets and liabilities accounted for using the fair value option	The following table summarizes the Company’s assets which are accounted for using the fair value option: September 30, December 31, Fixed maturities $ 908,802 $ 1,245,562 Other investments 2,440,120 2,311,939 Short-term investments 390,980 322,177 Equity securities 98,341 103,893 Investments accounted for using the fair value option $ 3,838,243 $ 3,983,571
Summary of investments in limited partnership interests where the Company has a variable interest	The following table summarizes investments in limited partnership interests where the Company has a variable interest by balance sheet line item: September 30, December 31, Investments accounted for using the equity method (1) 1,575,832 1,493,791 Investments accounted for using the fair value option (2) 189,186 162,398 Total $ 1,765,018 $ 1,656,189 (1) Aggregate unfunded commitments were $1.44 billion at September 30, 2019 , compared to $1.22 billion at December 31, 2018 . (2) Aggregate unfunded commitments were $51.1 million at September 30, 2019 , compared to $117.5 million at December 31, 2018 .
Components of net investment income	The components of net investment income were derived from the following sources: September 30, 2019 2018 Three Months Ended Fixed maturities $ 126,889 $ 120,516 Term loans 24,236 21,903 Equity securities 3,992 3,165 Short-term investments 3,834 4,547 Other (1) 22,704 17,195 Gross investment income 181,655 167,326 Investment expenses (20,167 ) (23,302 ) Net investment income $ 161,488 $ 144,024 Nine Months Ended Fixed maturities $ 381,706 $ 343,513 Term loans 73,582 62,430 Equity securities 11,348 10,510 Short-term investments 11,872 13,799 Other (1) 62,423 52,210 Gross investment income 540,931 482,462 Investment expenses (67,456 ) (76,046 ) Net investment income $ 473,475 $ 406,416 (1)
Summary of net realized gains (losses), excluding other-than-temporary impairment provisions	Net realized gains (losses) were as follows, excluding net impairment losses recognized in earnings: September 30, 2019 2018 Three Months Ended Available for sale securities: Gross gains on investment sales $ 73,685 $ 10,990 Gross losses on investment sales (30,561 ) (34,879 ) Change in fair value of assets and liabilities accounted for using the fair value option: Fixed maturities (3,895 ) (6,604 ) Other investments (21,778 ) (7,950 ) Equity securities (1,231 ) 2,752 Short-term investments (1,941 ) (471 ) Equity securities, at fair value: Net realized gains (losses) on sales during the period 5,217 (2,012 ) Net unrealized gains (losses) on equity securities still held at reporting date (1,206 ) 10,798 Derivative instruments (1) 42,893 (17,556 ) Other (2) 1,335 (6,773 ) Net realized gains (losses) $ 62,518 $ (51,705 ) Nine Months Ended Available for sale securities: Gross gains on investment sales $ 192,140 $ 44,732 Gross losses on investment sales (77,498 ) (175,141 ) Change in fair value of assets and liabilities accounted for using the fair value option: Fixed maturities 38,682 (47,082 ) Other investments (37,363 ) (14,578 ) Equity securities 9,449 10,650 Short-term investments (2,613 ) (758 ) Equity securities, at fair value: Net realized gains (losses) on sales during the period 9,503 (13,298 ) Net unrealized gains (losses) on equity securities still held at reporting date 58,562 (4,063 ) Derivative instruments (1) 142,730 (23,665 ) Other (2) (8,703 ) (16,111 ) Net realized gains (losses) $ 324,889 $ (239,314 ) (1) See note 8 for information on the Company’s derivative instruments. (2) Includes the re-measurement of contingent consideration liability amounts.
Summary of OTTI recognized in earnings by asset class	The following table details the net impairment losses recognized in earnings by asset class: September 30, 2019 2018 Three Months Ended Fixed maturities: Mortgage backed securities $ (284 ) $ (73 ) Corporate bonds (666 ) (270 ) Non-U.S. government securities — (149 ) Asset backed securities (213 ) — Net impairment losses recognized in earnings $ (1,163 ) $ (492 ) Nine Months Ended Fixed maturities: Mortgage backed securities $ (839 ) $ (196 ) Corporate bonds (1,256 ) (631 ) Non-U.S. government securities — (149 ) Asset backed securities (426 ) (148 ) Net impairment losses recognized in earnings $ (2,521 ) $ (1,124 )
Rollforward of the amount related to credit losses recognized in earnings for which a portion was recognized in AOCI	The following table provides a roll forward of the amount related to credit losses recognized in earnings for which a portion of an OTTI was recognized in accumulated other comprehensive income: September 30, 2019 2018 Three Months Ended Balance at start of period $ 346 $ 698 Credit loss impairments recognized on securities not previously impaired — — Credit loss impairments recognized on securities previously impaired — — Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security — — Reductions for securities sold during the period — (47 ) Balance at end of period $ 346 $ 651 Nine Months Ended Balance at start of year $ 637 $ 767 Credit loss impairments recognized on securities not previously impaired — — Credit loss impairments recognized on securities previously impaired — — Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security — — Reductions for securities sold during the period (291 ) (116 ) Balance at end of period $ 346 $ 651
Summary of restricted assets	The following table details the value of the Company’s restricted assets: September 30, December 31, Assets used for collateral or guarantees: Affiliated transactions $ 4,629,369 $ 4,623,483 Third party agreements 2,605,587 2,181,682 Deposits with U.S. regulatory authorities 788,295 689,114 Deposits with non-U.S. regulatory authorities 71,800 59,624 Total restricted assets $ 8,095,051 $ 7,553,903
Reconciliation of cash and restricted cash	The following table details reconciliation of cash and restricted cash within the Consolidated Balance Sheets: September 30, December 31, Cash $ 880,099 $ 646,556 Restricted cash (included in ‘other assets’) $ 82,376 $ 78,087 Cash and restricted cash $ 962,475 $ 724,643

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair value hierarchy	The following table presents the Company’s financial assets and liabilities measured at fair value by level at September 30, 2019 : Estimated Fair Value Measurements Using: Estimated Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets measured at fair value (1): Available for sale securities: Fixed maturities: Corporate bonds $ 6,269,993 $ — $ 6,261,248 $ 8,745 Mortgage backed securities 544,033 — 543,761 272 Municipal bonds 653,346 — 653,346 — Commercial mortgage backed securities 754,306 — 754,306 — U.S. government and government agencies 5,127,290 5,005,512 121,778 — Non-U.S. government securities 1,873,856 — 1,873,856 — Asset backed securities 1,657,494 — 1,652,045 5,449 Total 16,880,318 5,005,512 11,860,340 14,466 Short-term investments 751,989 720,518 31,471 — Equity securities, at fair value 561,105 514,380 11,402 35,323 Derivative instruments (4) 51,647 — 51,647 — Fair value option: Corporate bonds 619,779 — 597,000 22,779 Non-U.S. government bonds 61,755 — 61,755 — Mortgage backed securities 15,512 — 15,512 — Municipal bonds 1,140 — 1,140 — Asset backed securities 208,620 — 208,620 — U.S. government and government agencies 1,996 1,886 110 — Short-term investments 390,980 376,033 14,947 — Equity securities 98,340 41,333 735 56,272 Other investments 1,411,420 41,316 1,284,661 85,443 Other investments measured at net asset value (2) 1,028,700 Total 3,838,242 460,568 2,184,480 164,494 Total assets measured at fair value $ 22,083,301 $ 6,700,978 $ 14,139,340 $ 214,283 Liabilities measured at fair value: Contingent consideration liabilities $ (7,344 ) $ — $ — $ (7,344 ) Securities sold but not yet purchased (3) (65,736 ) — (65,736 ) — Derivative instruments (4) (53,740 ) — (53,740 ) — Total liabilities measured at fair value $ (126,820 ) $ — $ (119,476 ) $ (7,344 ) (1) In securities lending transactions, the Company receives collateral in excess of the fair value of the securities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See note 6 , “—Securities Lending Agreements.” (2) In accordance with applicable accounting guidance, certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. (3) Represents the Company’s obligations to deliver securities that it did not own at the time of sale. Such amounts are included in “other liabilities” on the Company’s consolidated balance sheets. (4) See note 8 . The following table presents the Company’s financial assets and liabilities measured at fair value by level at December 31, 2018 : Estimated Fair Value Measurements Using: Estimated Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets measured at fair value (1): Available for sale securities: Fixed maturities: Corporate bonds $ 5,537,548 $ — $ 5,529,407 $ 8,141 Mortgage backed securities 541,193 — 540,884 309 Municipal bonds 1,013,395 — 1,013,395 — Commercial mortgage backed securities 729,442 — 729,438 4 U.S. government and government agencies 3,758,698 3,657,181 101,517 — Non-U.S. government securities 1,771,338 — 1,771,338 — Asset backed securities 1,600,896 — 1,600,896 — Total 14,952,510 3,657,181 11,286,875 8,454 Equity securities 353,794 321,927 31,867 — Short-term investments 955,880 875,881 79,999 — Derivative instruments (4) 73,893 — 73,893 — Fair value option: Corporate bonds 852,585 — 846,827 5,758 Non-U.S. government bonds 79,066 — 79,066 — Mortgage backed securities 16,731 — 16,731 — Municipal bonds 7,144 — 7,144 — Asset backed securities 178,790 — 178,790 — U.S. government and government agencies 111,246 111,138 108 — Short-term investments 322,177 278,579 43,598 — Equity securities 103,893 48,827 55,066 — Other investments 1,254,220 39,107 1,152,408 62,705 Other investments measured at net asset value (2) 1,057,719 Total 3,983,571 477,651 2,379,738 68,463 Total assets measured at fair value $ 20,319,648 $ 5,332,640 $ 13,852,372 $ 76,917 Liabilities measured at fair value: Contingent consideration liabilities $ (66,665 ) $ — $ — $ (66,665 ) Securities sold but not yet purchased (3) (7,790 ) — (7,790 ) — Derivative instruments (4) (20,664 ) — (20,664 ) — Total liabilities measured at fair value $ (95,119 ) $ — $ (28,454 ) $ (66,665 ) (1) In securities lending transactions, the Company receives collateral in excess of the fair value of the securities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See note 6 , “—Securities Lending Agreements.” (2) In accordance with applicable accounting guidance, certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets. (3) Represents the Company’s obligations to deliver securities that it did not own at the time of sale. Such amounts are included in “other liabilities” on the Company’s consolidated balance sheets. (4) See note 8 .
Rollforward of Level 3 investments	The following table presents a reconciliation of the beginning and ending balances for all financial assets and liabilities measured at fair value on a recurring basis using Level 3 inputs: Assets Liabilities s Available For Sale Fair Value Option Fair Value Structured Securities (1) Corporate Corporate Other Investments Equity Securities Equity Securities Contingent Consideration Liabilities Three Months Ended September 30, 2019 Balance at beginning of period $ 290 $ 7,642 $ 26,103 $ 95,273 $ 56,145 $ 51,212 $ (7,825 ) Total gains or (losses) (realized/unrealized) Included in earnings (2) — — (1,227 ) (411 ) 127 (26 ) (79 ) Included in other comprehensive income — (301 ) — — — — — Purchases, issuances, sales and settlements Purchases — — — 3,713 — 12,119 — Issuances — — — — — — — Sales — — (2,097 ) (80 ) — (27,982 ) — Settlements (18 ) (456 ) — — — — 560 Transfers in and/or out of Level 3 5,449 1,860 — (13,052 ) — — — Balance at end of period $ 5,721 $ 8,745 $ 22,779 $ 85,443 $ 56,272 $ 35,323 $ (7,344 ) Three Months Ended September 30, 2018 Balance at beginning of period $ 376 $ 8,773 $ 11,335 $ 58,214 $ — $ — $ (63,930 ) Total gains or (losses) (realized/unrealized) Included in earnings (2) — (1 ) (503 ) (1,459 ) — — (1,711 ) Included in other comprehensive income 2 (32 ) — — — — — Purchases, issuances, sales and settlements Purchases — — — 6,250 — — — Issuances — — — — — — — Sales — — — (74 ) — — — Settlements (33 ) (456 ) (1,226 ) — — — — Transfers in and/or out of Level 3 — — — — — — — Balance at end of period $ 345 $ 8,284 $ 9,606 $ 62,931 $ — $ — $ (65,641 ) Nine Months Ended September 30, 2019 Balance at beginning of year $ 313 $ 8,141 $ 5,758 $ 62,705 $ — $ — $ (66,665 ) Total gains or (losses) (realized/unrealized) Included in earnings (2) 1,757 — (1,566 ) (11,727 ) 127 (26 ) (1,410 ) Included in other comprehensive income 5 (317 ) — — — — — Purchases, issuances, sales and settlements Purchases — 429 — 3,713 — 12,119 — Issuances — — — — — — (548 ) Sales (1,757 ) — (5,332 ) (228 ) — (27,982 ) — Settlements (46 ) (1,368 ) — (600 ) — — 61,279 Transfers in and/or out of Level 3 5,449 1,860 23,919 31,580 56,145 51,212 — Balance at end of period $ 5,721 $ 8,745 $ 22,779 $ 85,443 $ 56,272 $ 35,323 $ (7,344 ) Nine Months Ended September 30, 2018 Balance at beginning of year $ 5,927 $ 9,460 $ 12,217 $ 59,167 $ — $ — $ (60,996 ) Total gains or (losses) (realized/unrealized) Included in earnings (2) 4 (1 ) (1,115 ) (1,838 ) — — (4,645 ) Included in other comprehensive income (6 ) (200 ) — — — — — Purchases, issuances, sales and settlements Purchases — 393 — 6,250 — — — Issuances — — — — — — — Sales (5,003 ) — — (148 ) — — — Settlements (577 ) (1,368 ) (1,496 ) (500 ) — — — Transfers in and/or out of Level 3 — — — — — — — Balance at end of period $ 345 $ 8,284 $ 9,606 $ 62,931 $ — $ — $ (65,641 ) (1) Includes asset backed securities, mortgage backed securities and commercial mortgage backed securities. (2) Gains or losses were included in net realized gains (losses).

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair value and notional amount of derivatives	The following table summarizes information on the fair values and notional values of the Company’s derivative instruments: Estimated Fair Value Asset Derivatives Liability Derivatives Notional Value (1) September 30, 2019 Futures contracts (2) $ 15,148 $ (20,515 ) $ 3,987,260 Foreign currency forward contracts (2) 5,316 (8,616 ) 965,348 TBAs (3) 54,961 — 53,229 Other (2) 31,183 (24,609 ) 3,983,466 Total $ 106,608 $ (53,740 ) December 31, 2018 Futures contracts (2) $ 51,800 $ (2,115 ) $ 3,153,518 Foreign currency forward contracts (2) 8,147 (7,796 ) 1,008,907 TBAs (3) 8,292 — 8,132 Other (2) 13,946 (10,753 ) 2,213,981 Total $ 82,185 $ (20,664 ) (1) Represents the absolute notional value of all outstanding contracts, consisting of long and short positions. (2) The fair value of asset derivatives are included in ‘other assets’ and the fair value of liability derivatives are included in ‘other liabilities.’ (3) The fair value of TBAs are included in ‘fixed maturities available for sale, at fair value.’
Summary of net realized gains (losses) recorded in the consolidated statements of income	Realized and unrealized contract gains and losses on the Company’s derivative instruments are reflected in ‘net realized gains (losses)’ in the consolidated statements of income, as summarized in the following table: Derivatives not designated as September 30, hedging instruments: 2019 2018 Three Months Ended Net realized gains (losses): Futures contracts $ 46,194 $ (15,399 ) Foreign currency forward contracts 2,044 (5,458 ) TBAs 269 (3 ) Other (5,614 ) 3,304 Total $ 42,893 $ (17,556 ) Nine Months Ended Net realized gains (losses): Futures contracts $ 140,503 $ (10,609 ) Foreign currency forward contracts (17,030 ) (13,074 ) TBAs 507 (100 ) Other 18,750 118 Total $ 142,730 $ (23,665 )

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Additional information regarding operating leases	Additional information regarding the Company’s operating leases is as follows: September 30, 2019 Three Months Ended Operating lease costs $ 7,751 Cash payments included in the measurement of lease liabilities reported in operating cash flows $ 8,031 Right-of-use assets obtained in exchange for new lease liabilities $ 2,897 Right-of-use assets (1) $ 131,424 Operating lease liability (1) $ 147,326 Weighted average discount rate 3.9 % Weighted average remaining lease term 6.3 years Nine Months Ended Operating lease costs $ 22,611 Cash payments included in the measurement of lease liabilities reported in operating cash flows $ 22,616 Right-of-use assets obtained in exchange for new lease liabilities $ 7,009 Right-of-use assets (1) $ 131,424 Operating lease liability (1) $ 147,326 Weighted average discount rate 3.9 % Weighted average remaining lease term 6.3 years (1) The right-of-use assets are included in ‘other assets’ while the operating lease liability is included in ‘other liabilities.’
Contractual maturities of lease liabilities	The following table presents the contractual maturities of the Company's operating lease liabilities at September 30, 2019 : Years Ending December 31, 2019 (remainder) $ 1,693 2020 31,541 2021 30,392 2022 27,096 2023 22,290 2024 and thereafter 55,080 Total undiscounted lease liability $ 168,092 Less: present value adjustment (20,767 ) Operating lease liability $ 147,325
Future minimum rental commitments	At December 31, 2018 , the future minimum rental commitments, exclusive of escalation clauses and maintenance costs and net of rental income, for all of the Company’s operating leases was as follows: 2019 $ 31,088 2020 30,491 2021 29,351 2022 26,068 2023 21,408 2024 and thereafter 54,745 Total $ 193,151

Variable Interest Entities an_2

Variable Interest Entities and Noncontrolling Interests (Tables)	9 Months Ended
	Sep. 30, 2019
Noncontrolling Interest [Abstract]
Carrying value of assets and liabilities of variable interest entity	The following table provides the carrying amount and balance sheet caption in which the assets and liabilities of Watford are reported: September 30, December 31, 2019 2018 Assets Investments accounted for using the fair value option $ 2,048,295 $ 2,312,003 Fixed maturities available for sale, at fair value 678,094 393,351 Equity securities, at fair value 43,488 32,206 Cash 80,390 63,529 Accrued investment income 18,277 19,461 Premiums receivable 302,265 227,301 Reinsurance recoverable on unpaid and paid losses and LAE 144,437 86,445 Ceded unearned premiums 129,909 61,587 Deferred acquisition costs 67,241 80,858 Receivable for securities sold 25,283 24,507 Goodwill and intangible assets 7,650 7,650 Other assets 66,165 63,959 Total assets of consolidated VIE $ 3,611,494 $ 3,372,857 Liabilities Reserve for losses and loss adjustment expenses $ 1,164,945 $ 1,032,760 Unearned premiums 454,148 390,114 Reinsurance balances payable 79,264 21,034 Revolving credit agreement borrowings 490,720 455,682 Senior notes 172,350 — Payable for securities purchased 40,586 60,142 Other liabilities (1) 196,431 302,524 Total liabilities of consolidated VIE $ 2,598,444 $ 2,262,256 Redeemable noncontrolling interests $ 52,281 $ 220,992 (1) Includes certain borrowings related to investing activities.
Activity in non-redeemable noncontrolling interests	The following table sets forth activity in the non-redeemable noncontrolling interests: September 30, 2019 2018 Three Months Ended Balance, beginning of period $ 855,347 $ 861,153 Additional paid in capital attributable to noncontrolling interests 205 — Amounts attributable to noncontrolling interests 136 16,759 Other comprehensive income (loss) attributable to noncontrolling interests (764 ) (1,158 ) Balance, end of period $ 854,924 $ 876,754 Nine Months Ended Balance, beginning of year $ 791,560 $ 843,411 Additional paid in capital attributable to noncontrolling interests 2,279 — Amounts attributable to noncontrolling interests 54,819 36,251 Other comprehensive income (loss) attributable to noncontrolling interests 6,266 (2,908 ) Balance, end of period $ 854,924 $ 876,754
Activity in redeemable noncontrolling interests	The following table sets forth activity in the redeemable non-controlling interests: September 30, 2019 2018 Three Months Ended Balance, beginning of period $ 206,475 $ 206,105 Redemption of noncontrolling interests (157,709 ) — Accretion of preference share issuance costs 23 94 Balance, end of period $ 48,789 $ 206,199 Nine Months Ended Balance, beginning of year $ 206,292 $ 205,922 Redemption of noncontrolling interests (157,709 ) — Accretion of preference share issuance costs 206 277 Balance, end of period $ 48,789 $ 206,199
Portion of income or loss attributable to third party investors	The portion of Watford’s income or loss attributable to third party investors, recorded in the Company’s consolidated statements of income in ‘net (income) loss attributable to noncontrolling interests,’ are summarized in the table below: September 30, 2019 2018 Three Months Ended Amounts attributable to non-redeemable noncontrolling interests $ (136 ) $ (16,759 ) Dividends attributable to redeemable noncontrolling interests (6,600 ) (4,599 ) Net (income) loss attributable to noncontrolling interests $ (6,736 ) $ (21,358 ) Nine Months Ended Amounts attributable to non-redeemable noncontrolling interests $ (54,819 ) $ (36,251 ) Dividends attributable to redeemable noncontrolling interests (15,778 ) (13,769 ) Net (income) loss attributable to noncontrolling interests $ (70,597 ) $ (50,020 )
Total assets and maximum exposure to loss associated with VIEs	The following table presents the total assets of the Bellemeade entities, as well as the Company’s maximum exposure to loss associated with these VIEs, calculated as the maximum historical observable spread between the one month LIBOR, the basis for the contractual payments to bond holders, and short term invested trust asset yields. Maximum Exposure to Loss Bellemeade Entities (Issue Date) Total VIE Assets On-Balance Sheet (Asset) Liability Off-Balance Sheet Total Sep 30, 2019 Bellemeade 2015-1 Ltd. (Jul-15) $ 6,046 $ — $ 2 $ 2 Bellemeade 2017-1 Ltd. (Oct-17) 249,737 (345 ) 3,526 3,181 Bellemeade 2018-1 Ltd. (Apr-18) 362,603 (1,351 ) 7,035 5,684 Bellemeade 2018-2 Ltd. (Aug-18) 507,534 (829 ) 3,395 2,566 Bellemeade 2018-3 Ltd. (Oct-18) 488,430 (916 ) 4,600 3,684 Bellemeade 2019-1 Ltd. (Mar-19) 293,595 (210 ) 4,533 4,323 Bellemeade 2019-2 Ltd. (Apr-19) 621,022 (367 ) 15,161 14,794 Bellemeade 2019-3 Ltd. (July-19) 700,920 (468 ) 11,888 11,420 Total $ 3,229,887 $ (4,486 ) $ 50,140 $ 45,654 Dec 31, 2018 Bellemeade 2015-1 Ltd. (Jul-15) $ 43,246 $ 112 $ 498 $ 610 Bellemeade 2017-1 Ltd. (Oct-17) 304,373 165 1,312 1,477 Bellemeade 2018-1 Ltd. (Apr-18) 374,460 132 3,539 3,671 Bellemeade 2018-2 Ltd. (Aug-18) 653,278 874 4,005 4,879 Bellemeade 2018-3 Ltd. (Oct-18) 506,110 469 1,836 2,305 Total $ 1,881,467 $ 1,752 $ 11,190 $ 12,942

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2019
Comprehensive Income Note Disclosure [Abstract]
Details about amounts reclassified from AOCI	The following tables present details about amounts reclassified from accumulated other comprehensive income and the tax effects allocated to each component of other comprehensive income (loss): Amounts Reclassified from AOCI Consolidated Statement of Income Three Months Ended Nine Months Ended Details About Line Item That Includes September 30, September 30, AOCI Components Reclassification 2019 2018 2019 2018 Unrealized appreciation on available-for-sale investments Net realized gains (losses) $ 43,124 $ (23,888 ) $ 114,642 $ (130,409 ) Other-than-temporary impairment losses (1,163 ) (492 ) (2,521 ) (1,124 ) Total before tax 41,961 (24,380 ) 112,121 (131,533 ) Income tax (expense) benefit (3,218 ) 1,177 (7,812 ) 9,226 Net of tax $ 38,743 $ (23,203 ) $ 104,309 $ (122,307 )
Schedule of comprehensive income (loss)	Before Tax Amount Tax Expense (Benefit) Net of Tax Amount Three Months Ended September 30, 2019 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ 70,449 $ 11,159 $ 59,290 Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) — — — Less reclassification of net realized gains (losses) included in net income 41,961 3,218 38,743 Foreign currency translation adjustments (16,507 ) (83 ) (16,424 ) Other comprehensive income (loss) $ 11,981 $ 7,858 $ 4,123 Three Months Ended September 30, 2018 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ (57,812 ) $ (4,504 ) $ (53,308 ) Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) — — — Less reclassification of net realized gains (losses) included in net income (24,380 ) (1,177 ) (23,203 ) Foreign currency translation adjustments 2,167 104 2,063 Other comprehensive income (loss) $ (31,265 ) $ (3,223 ) $ (28,042 ) Nine Months Ended September 30, 2019 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ 573,513 $ 65,863 $ 507,650 Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) — — — Less reclassification of net realized gains (losses) included in net income 112,121 7,812 104,309 Foreign currency translation adjustments (6,454 ) 187 (6,641 ) Other comprehensive income (loss) $ 454,938 $ 58,238 $ 396,700 Nine Months Ended September 30, 2018 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ (335,789 ) $ (30,533 ) $ (305,256 ) Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) — — — Less reclassification of net realized gains (losses) included in net income (131,533 ) (9,226 ) (122,307 ) Foreign currency translation adjustments (9,102 ) 148 (9,250 ) Other comprehensive income (loss) $ (213,358 ) $ (21,159 ) $ (192,199 )

Guarantor Financial Informati_2

Guarantor Financial Information (Tables)	9 Months Ended
	Sep. 30, 2019
Condensed Financial Information Disclosure [Abstract]
Condensed consolidating balance sheet	September 30, 2019 Condensed Consolidating Balance Sheet Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Assets Total investments $ 41 $ 918,720 $ 22,737,556 $ (38,982 ) $ 23,617,335 Cash 12,696 72,727 794,676 — 880,099 Investments in subsidiaries 11,454,186 4,189,656 — (15,643,842 ) — Due from subsidiaries and affiliates 106 2 1,899,559 (1,899,667 ) — Premiums receivable — — 2,446,539 (828,353 ) 1,618,186 Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses — — 8,490,131 (5,321,936 ) 3,168,195 Contractholder receivables — — 2,094,683 — 2,094,683 Ceded unearned premiums — — 2,149,492 (981,234 ) 1,168,258 Deferred acquisition costs — — 674,559 (52,531 ) 622,028 Goodwill and intangible assets — — 624,500 — 624,500 Other assets 21,336 25,586 1,875,817 (143,420 ) 1,779,319 Total assets $ 11,488,365 $ 5,206,691 $ 43,787,512 $ (24,909,965 ) $ 35,572,603 Liabilities Reserve for losses and loss adjustment expenses $ — $ — $ 17,486,844 $ (5,097,460 ) $ 12,389,384 Unearned premiums — — 5,224,606 (981,234 ) 4,243,372 Reinsurance balances payable — — 1,430,244 (828,353 ) 601,891 Contractholder payables — — 2,094,683 — 2,094,683 Collateral held for insured obligations — — 205,449 205,449 Senior notes 297,228 494,803 1,114,355 (35,000 ) 1,871,386 Revolving credit agreement borrowings — — 490,720 — 490,720 Due to subsidiaries and affiliates 8 542,103 1,357,556 (1,899,667 ) — Other liabilities 33,033 55,585 1,946,208 (420,917 ) 1,613,909 Total liabilities 330,269 1,092,491 31,350,665 (9,262,631 ) 23,510,794 Redeemable noncontrolling interests — — 52,281 (3,492 ) 48,789 Shareholders’ Equity Total shareholders’ equity available to Arch 11,158,096 4,114,200 11,529,642 (15,643,842 ) 11,158,096 Non-redeemable noncontrolling interests — — 854,924 — 854,924 Total shareholders’ equity 11,158,096 4,114,200 12,384,566 (15,643,842 ) 12,013,020 Total liabilities, noncontrolling interests and shareholders’ equity $ 11,488,365 $ 5,206,691 $ 43,787,512 $ (24,909,965 ) $ 35,572,603 December 31, 2018 Condensed Consolidating Balance Sheet Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Assets Total investments $ 104 $ 452,674 $ 21,307,206 $ (14,700 ) $ 21,745,284 Cash 6,125 5,940 634,491 — 646,556 Investments in subsidiaries 9,735,256 3,999,243 — (13,734,499 ) — Due from subsidiaries and affiliates 9 2 1,802,686 (1,802,697 ) — Premiums receivable — — 1,834,389 (535,239 ) 1,299,150 Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses — — 8,618,660 (5,699,288 ) 2,919,372 Contractholder receivables — — 2,079,111 — 2,079,111 Ceded unearned premiums — — 1,730,262 (754,793 ) 975,469 Deferred acquisition costs — — 618,535 (48,961 ) 569,574 Goodwill and intangible assets — — 634,920 — 634,920 Other assets 12,588 80,949 1,466,438 (211,082 ) 1,348,893 Total assets $ 9,754,082 $ 4,538,808 $ 40,726,698 $ (22,801,259 ) $ 32,218,329 Liabilities Reserve for losses and loss adjustment expenses $ — $ — $ 17,345,142 $ (5,491,845 ) $ 11,853,297 Unearned premiums — — 4,508,429 (754,793 ) 3,753,636 Reinsurance balances payable — — 928,346 (535,239 ) 393,107 Contractholder payables — — 2,079,111 — 2,079,111 Collateral held for insured obligations — — 236,630 — 236,630 Senior notes 297,150 494,723 941,655 — 1,733,528 Revolving credit agreement borrowings — — 455,682 — 455,682 Due to subsidiaries and affiliates — 536,805 1,265,892 (1,802,697 ) — Other liabilities 17,105 26,270 1,699,768 (467,484 ) 1,275,659 Total liabilities 314,255 1,057,798 29,460,655 (9,052,058 ) 21,780,650 Redeemable noncontrolling interests — — 220,992 (14,700 ) 206,292 Shareholders’ Equity Total shareholders’ equity available to Arch 9,439,827 3,481,010 10,253,491 (13,734,501 ) 9,439,827 Non-redeemable noncontrolling interests — — 791,560 — 791,560 Total shareholders’ equity 9,439,827 3,481,010 11,045,051 (13,734,501 ) 10,231,387 Total liabilities, noncontrolling interests and shareholders’ equity $ 9,754,082 $ 4,538,808 $ 40,726,698 $ (22,801,259 ) $ 32,218,329
Condensed consolidating statement of income and comprehensive income	Three Months Ended September 30, 2019 Condensed Consolidating Statement of Income and Comprehensive Income Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Revenues Net premiums earned $ — $ — $ 1,438,023 $ — $ 1,438,023 Net investment income 81 2,899 181,621 (23,113 ) 161,488 Net realized gains (losses) — 1,880 66,683 (6,045 ) 62,518 Net impairment losses recognized in earnings — — (1,163 ) — (1,163 ) Other underwriting income — — 3,326 — 3,326 Equity in net income (loss) of investment funds accounted for using the equity method — 600 16,530 — 17,130 Other income (loss) (153 ) — 1,491 — 1,338 Total revenues (72 ) 5,379 1,706,511 (29,158 ) 1,682,660 Expenses Losses and loss adjustment expenses — — 802,455 — 802,455 Acquisition expenses — — 211,120 — 211,120 Other operating expenses — — 196,512 — 196,512 Corporate expenses 15,066 1,631 364 — 17,061 Amortization of intangible assets — — 20,003 — 20,003 Interest expense 5,539 12,019 36,712 (22,942 ) 31,328 Net foreign exchange (gains) losses 1 — (25,405 ) (7,720 ) (33,124 ) Total expenses 20,606 13,650 1,241,761 (30,662 ) 1,245,355 Income (loss) before income taxes (20,678 ) (8,271 ) 464,750 1,504 437,305 Income tax (expense) benefit — 1,647 (39,763 ) — (38,116 ) Income (loss) before equity in net income of subsidiaries (20,678 ) (6,624 ) 424,987 1,504 399,189 Equity in net income of subsidiaries 413,131 124,814 — (537,945 ) — Net income 392,453 118,190 424,987 (536,441 ) 399,189 Net (income) loss attributable to noncontrolling interests — — (6,906 ) 170 (6,736 ) Net income available to Arch 392,453 118,190 418,081 (536,271 ) 392,453 Preferred dividends (10,403 ) — — — (10,403 ) Net income available to Arch common shareholders $ 382,050 $ 118,190 $ 418,081 $ (536,271 ) $ 382,050 Comprehensive income available to Arch $ 397,340 $ 138,832 $ 427,238 $ (566,070 ) $ 397,340 Three Months Ended September 30, 2018 Condensed Consolidating Statement of Income and Comprehensive Income Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Revenues Net premiums earned $ — $ — $ 1,290,878 $ — $ 1,290,878 Net investment income 2 1,202 165,289 (22,469 ) 144,024 Net realized gains (losses) — (64 ) (51,641 ) — (51,705 ) Net impairment losses recognized in earnings — — (492 ) — (492 ) Other underwriting income — — 5,823 — 5,823 Equity in net income (loss) of investment funds accounted for using the equity method — — 15,982 — 15,982 Other income (loss) (195 ) — (531 ) — (726 ) Total revenues (193 ) 1,138 1,425,308 (22,469 ) 1,403,784 Expenses Losses and loss adjustment expenses — — 699,420 — 699,420 Acquisition expenses — — 201,602 — 201,602 Other operating expenses — — 161,098 — 161,098 Corporate expenses 15,170 446 (1,281 ) — 14,335 Amortization of intangible assets — — 26,315 — 26,315 Interest expense 5,536 12,075 34,276 (22,157 ) 29,730 Net foreign exchange (gains) losses — — (10,426 ) (412 ) (10,838 ) Total expenses 20,706 12,521 1,111,004 (22,569 ) 1,121,662 Income (loss) before income taxes (20,899 ) (11,383 ) 314,304 100 282,122 Income tax (expense) benefit — 2,276 (35,632 ) — (33,356 ) Income (loss) before equity in net income of subsidiaries (20,899 ) (9,107 ) 278,672 100 248,766 Equity in net income of subsidiaries 248,307 92,906 — (341,213 ) — Net income (loss) 227,408 83,799 278,672 (341,113 ) 248,766 Net (income) loss attributable to noncontrolling interests — — (21,669 ) 311 (21,358 ) Net income (loss) available to Arch 227,408 83,799 257,003 (340,802 ) 227,408 Preferred dividends (10,402 ) — — — (10,402 ) Net income (loss) available to Arch common shareholders $ 217,006 $ 83,799 $ 257,003 $ (340,802 ) $ 217,006 Comprehensive income available to Arch $ 200,524 $ 77,389 $ 230,565 $ (307,954 ) $ 200,524 Nine Months Ended September 30, 2019 Condensed Consolidating Statement of Income and Comprehensive Income Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Revenues Net premiums earned $ — $ — $ 4,270,616 $ — $ 4,270,616 Net investment income 165 9,425 532,031 (68,146 ) 473,475 Net realized gains (losses) — 16,223 320,356 (11,690 ) 324,889 Net impairment losses recognized in earnings — — (2,521 ) — (2,521 ) Other underwriting income — — 18,104 — 18,104 Equity in net income (loss) of investment funds accounted for using the equity method — 536 95,997 — 96,533 Other income (loss) (634 ) — 4,184 — 3,550 Total revenues (469 ) 26,184 5,238,767 (79,836 ) 5,184,646 Expenses Losses and loss adjustment expenses — — 2,288,530 — 2,288,530 Acquisition expenses — — 619,057 — 619,057 Other operating expenses — — 596,589 — 596,589 Corporate expenses 46,666 5,912 696 — 53,274 Amortization of intangible assets — — 60,214 — 60,214 Interest expense 16,615 35,966 104,430 (67,338 ) 89,673 Net foreign exchange (gains) losses 3 — (26,715 ) (4,985 ) (31,697 ) Total expenses 63,284 41,878 3,642,801 (72,323 ) 3,675,640 Income (loss) before income taxes (63,753 ) (15,694 ) 1,595,966 (7,513 ) 1,509,006 Income tax (expense) benefit — 3,491 (131,965 ) — (128,474 ) Income (loss) before equity in net income of subsidiaries (63,753 ) (12,203 ) 1,464,001 (7,513 ) 1,380,532 Equity in net income of subsidiaries 1,373,688 410,115 — (1,783,803 ) — Net income 1,309,935 397,912 1,464,001 (1,791,316 ) 1,380,532 Net (income) loss attributable to noncontrolling interests — — (71,405 ) 808 (70,597 ) Net income available to Arch 1,309,935 397,912 1,392,596 (1,790,508 ) 1,309,935 Preferred dividends (31,209 ) — — — (31,209 ) Net income available to Arch common shareholders $ 1,278,726 $ 397,912 $ 1,392,596 $ (1,790,508 ) $ 1,278,726 Comprehensive income available to Arch $ 1,700,369 $ 608,108 $ 1,779,463 $ (2,387,571 ) $ 1,700,369 Nine Months Ended September 30, 2018 Condensed Consolidating Statement of Income and Comprehensive Income Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Revenues Net premiums earned $ — $ — $ 3,862,540 $ — $ 3,862,540 Net investment income 37 2,020 471,588 (67,229 ) 406,416 Net realized gains (losses) 29 (71 ) (239,272 ) — (239,314 ) Net impairment losses recognized in earnings — — (1,124 ) — (1,124 ) Other underwriting income — — 15,046 — 15,046 Equity in net income (loss) of investment funds accounted for using the equity method — — 52,523 — 52,523 Other income (loss) 2,066 — 395 — 2,461 Total revenues 2,132 1,949 4,161,696 (67,229 ) 4,098,548 Expenses Losses and loss adjustment expenses — — 2,062,433 — 2,062,433 Acquisition expenses — — 595,816 — 595,816 Other operating expenses — — 512,294 — 512,294 Corporate expenses 47,981 1,205 2,973 — 52,159 Amortization of intangible assets — — 79,523 — 79,523 Interest expense 16,609 36,014 104,359 (66,272 ) 90,710 Net foreign exchange (gains) losses 29 — (37,347 ) (7,505 ) (44,823 ) Total expenses 64,619 37,219 3,320,051 (73,777 ) 3,348,112 Income (loss) before income taxes (62,487 ) (35,270 ) 841,645 6,548 750,436 Income tax (expense) benefit — 7,704 (86,643 ) — (78,939 ) Income (loss) before equity in net income of subsidiaries (62,487 ) (27,566 ) 755,002 6,548 671,497 Equity in net income of subsidiaries 683,964 266,053 — (950,017 ) — Net income 621,477 238,487 755,002 (943,469 ) 671,497 Net (income) loss attributable to noncontrolling interests — — (50,976 ) 956 (50,020 ) Net income available to Arch 621,477 238,487 704,026 (942,513 ) 621,477 Preferred dividends (31,242 ) — — — (31,242 ) Loss on redemption of preferred shares (2,710 ) — — — (2,710 ) Net income available to Arch common shareholders $ 587,525 $ 238,487 $ 704,026 $ (942,513 ) $ 587,525 Comprehensive income available to Arch $ 432,186 $ 153,992 $ 522,448 $ (676,440 ) $ 432,186
Condensed consolidating statement of cash flows	Nine Months Ended September 30, 2019 Condensed Consolidating Statement of Cash Flows Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Operating Activities Net Cash Provided By (Used For) Operating Activities $ 42,221 $ 525,712 $ 1,554,406 $ (579,200 ) $ 1,543,139 Investing Activities Purchases of fixed maturity investments — (868,773 ) (23,313,996 ) 172,146 (24,010,623 ) Purchases of equity securities — (74,502 ) (520,292 ) 70,743 (524,051 ) Purchases of other investments — (28,557 ) (986,368 ) — (1,014,925 ) Proceeds from the sales of fixed maturity investments — 482,804 22,373,404 (148,354 ) 22,707,854 Proceeds from the sales of equity securities — 7,441 434,432 (70,743 ) 371,130 Proceeds from the sales, redemptions and maturities of other investments — 1,057 826,460 — 827,517 Proceeds from redemptions and maturities of fixed maturity investments — — 394,719 — 394,719 Net settlements of derivative instruments — — 92,423 — 92,423 Net (purchases) sales of short-term investments 63 31,605 97,410 — 129,078 Change in cash collateral related to securities lending — — 6,990 — 6,990 Contributions to subsidiaries (2,121 ) — (70,125 ) 72,246 — Issuance of intercompany loans — — (53,828 ) 53,828 — Purchases of fixed assets (32 ) — (27,603 ) — (27,635 ) Other — (10,000 ) (192,953 ) — (202,953 ) Net Cash Provided By (Used For) Investing Activities (2,090 ) (458,925 ) (939,327 ) 149,866 (1,250,476 ) Financing Activities Purchases of common shares under share repurchase program (2,871 ) — — — (2,871 ) Proceeds from common shares issued, net 518 — 72,246 (72,246 ) 518 Proceeds from intercompany borrowings — — 53,828 (53,828 ) — Proceeds from borrowings — — 235,083 (35,000 ) 200,083 Repayments of intercompany borrowings — — — — — Repayments of borrowings — — (27,538 ) — (27,538 ) Change in cash collateral related to securities lending — — (6,990 ) — (6,990 ) Change in third party investment in redeemable noncontrolling interests — — (173,082 ) 11,208 (161,874 ) Dividends paid to redeemable noncontrolling interests — — (12,217 ) 809 (11,408 ) Dividends paid to parent (1) — — (578,391 ) 578,391 — Other — — (5,207 ) — (5,207 ) Preferred dividends paid (31,209 ) — — — (31,209 ) Net Cash Provided By (Used For) Financing Activities (33,562 ) — (442,268 ) 429,334 (46,496 ) Effects of exchange rates changes on foreign currency cash and restricted cash — — (8,335 ) — (8,335 ) Increase (decrease) in cash and restricted cash 6,569 66,787 164,476 — 237,832 Cash and restricted cash, beginning of year 6,159 5,940 712,544 — 724,643 Cash and restricted cash, end of period $ 12,728 $ 72,727 $ 877,020 $ — $ 962,475 (1) Dividends received by parent are included in net cash provided by (used for) operating activities. Nine Months Ended September 30, 2018 Condensed Consolidating Statement of Cash Flows Arch Capital (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other Arch Capital Subsidiaries Consolidating Adjustments and Eliminations Arch Capital Consolidated Operating Activities Net Cash Provided By (Used For) Operating Activities $ 222,097 $ 176,851 $ 1,622,248 $ (900,209 ) $ 1,120,987 Investing Activities Purchases of fixed maturity investments — (214,449 ) (25,229,184 ) 605,716 (24,837,917 ) Purchases of equity securities — — (819,342 ) — (819,342 ) Purchases of other investments — — (1,543,332 ) — (1,543,332 ) Proceeds from the sales of fixed maturity investments — 111,533 23,804,386 (605,716 ) 23,310,203 Proceeds from the sales of equity securities — — 866,919 — 866,919 Proceeds from the sales, redemptions and maturities of other investments — — 1,178,035 — 1,178,035 Proceeds from redemptions and maturities of fixed maturity investments — — 724,021 — 724,021 Net settlements of derivative instruments — — 765 — 765 Net (purchases) sales of short-term investments 96,397 (49,031 ) 506,949 — 554,315 Change in cash collateral related to securities lending — — 137,073 — 137,073 Contributions to subsidiaries — (2,500 ) (29,646 ) 32,146 — Purchases of fixed assets (71 ) — (18,979 ) — (19,050 ) Other (4 ) — 58,231 — 58,227 Net Cash Provided By (Used For) Investing Activities 96,322 (154,447 ) (364,104 ) 32,146 (390,083 ) Financing Activities Redemption of preferred shares (92,555 ) — — — (92,555 ) Purchases of common shares under share repurchase program (184,529 ) — — — (184,529 ) Proceeds from common shares issued, net (12,029 ) — 32,146 (32,146 ) (12,029 ) Proceeds from borrowings — — 167,259 — 167,259 Repayments of borrowings — — (427,000 ) — (427,000 ) Change in cash collateral related to securities lending — — (137,073 ) — (137,073 ) Dividends paid to redeemable noncontrolling interests — — (14,447 ) 956 (13,491 ) Dividends paid to parent (1) — — (899,253 ) 899,253 — Other — — (6,084 ) — (6,084 ) Preferred dividends paid (31,242 ) — — — (31,242 ) Net Cash Provided By (Used For) Financing Activities (320,355 ) — (1,284,452 ) 868,063 (736,744 ) Effects of exchange rates changes on foreign currency cash and restricted cash — — (11,625 ) — (11,625 ) Increase (decrease) in cash and restricted cash (1,936 ) 22,404 (37,933 ) — (17,465 ) Cash and restricted cash, beginning of year 10,048 30,380 686,856 — 727,284 Cash and restricted cash, end of period $ 8,112 $ 52,784 $ 648,923 $ — $ 709,819 (1) Dividends received by parent are included in net cash provided by (used for) operating activities.

Basis of Presentation and Rec_3

Basis of Presentation and Recent Accounting Pronouncements (Details) - USD ($)	Sep. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liability	$ 147,325,000
ASU 2018-11
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of an accounting change		$ 0
Other assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets	131,424,000
Other assets | ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets		147,900,000
Other liabilities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liability	$ 147,326,000
Other liabilities | ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liability		$ 163,600,000

Share Transactions - Share repu

Share Transactions - Share repurchases (Details) - USD ($) shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Class of Stock [Line Items]
Treasury stock, shares acquired (shares)	0.1	6.9
Shares repurchased for treasury	$ 2.9	$ 184.5
Common shares
Class of Stock [Line Items]
Cumulative number of shares acquired since inception of share repurchase program	386.3
Aggregate purchase price of shares acquired since inception of share repurchase program	$ 3,970
Remaining authorized repurchase amount	$ 160.9

Share Transactions - Conversion

Share Transactions - Conversion of Non-voting common equivalent preferred shares (Details) shares in Millions	1 Months Ended
	Mar. 31, 2018shares
Class of Stock [Line Items]
Number of common shares issued on conversion	17
Number of convertible shares transferred	0.6

Share Transactions - Series C P

Share Transactions - Series C Preferred Shares (Details) - Series C Preferred Shares	Jan. 02, 2018$ / shares
Class of Stock [Line Items]
Preferred shares, dividend rate	6.75%
Preferred shares, redemption price	$ 25

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Net income		$ 399,189	$ 248,766	$ 1,380,532	$ 671,497
Amounts attributable to noncontrolling interests		(6,736)	(21,358)	(70,597)	(50,020)
Net income available to Arch		392,453	227,408	1,309,935	621,477
Preferred dividends		(10,403)	(10,402)	(31,209)	(31,242)
Loss on redemption of preferred shares		0	0	0	(2,710)
Net income available to Arch common shareholders		$ 382,050	$ 217,006	$ 1,278,726	$ 587,525
Denominator:
Weighted average common shares outstanding		402,564,121	402,939,092	401,419,153	400,649,105
Series D preferred shares	[1]	0	0	0	4,427,123
Weighted average common shares outstanding — basic		402,564,121	402,939,092	401,419,153	405,076,228
Effect of dilutive common share equivalents:
Nonvested restricted shares		1,895,972	1,619,286	1,637,015	1,568,044
Stock options	[2]	8,720,108	7,162,836	7,751,234	7,348,920
Weighted average common shares and common share equivalents outstanding — diluted		413,180,201	411,721,214	410,807,402	413,993,192
Earnings per common share:
Basic (per share)		$ 0.95	$ 0.54	$ 3.19	$ 1.45
Diluted (per share)		$ 0.92	$ 0.53	$ 3.11	$ 1.42
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per common share (shares)		37,394	4,396,352	2,198,115	5,481,584
[1]	Such shares are convertible non-voting common equivalent preferred shares issued in connection with the UGC acquisition.
[2]	Certain stock options were not included in the computation of diluted earnings per share where the exercise price of the stock options exceeded the average market price and would have been anti-dilutive or where, when applying the treasury stock method to in-the-money options, the sum of the proceeds, including unrecognized compensation, exceeded the average market price and would have been anti-dilutive. For the 2019 third quarter and 2018 third quarter , the number of stock options excluded were 37,394 and 4,396,352 , respectively. For the nine months ended September 30, 2019 and 2018 period, the number of stock options excluded were 2,198,115 and 5,481,584 , respectively.

Segment Information - Summary o

Segment Information - Summary of underwriting income or loss by segment (Details) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2019USD ($)		Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)segment		Sep. 30, 2018USD ($)		Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Gross premiums written		$ 2,181,121		$ 1,731,328	$ 6,196,809		$ 5,266,086
Premiums ceded		(567,664)		(397,775)	(1,613,195)		(1,221,093)
Net premiums written		1,613,457		1,333,553	4,583,614		4,044,993
Change in unearned premiums		(175,434)		(42,675)	(312,998)		(182,453)
Net premiums earned		1,438,023		1,290,878	4,270,616		3,862,540
Other underwriting income		3,326		5,823	18,104		15,046
Losses and loss adjustment expenses		(802,455)		(699,420)	(2,288,530)		(2,062,433)
Acquisition expenses, net		(211,120)		(201,602)	(619,057)		(595,816)
Other operating expenses		(196,512)		(161,098)	(596,589)		(512,294)
Underwriting income (loss)		231,262		234,581	784,544		707,043
Net investment income		161,488		144,024	473,475		406,416
Net realized gains (losses)		62,518		(51,705)	324,889		(239,314)
Net impairment losses recognized in earnings		(1,163)		(492)	(2,521)		(1,124)
Equity in net income of investment funds accounted for using the equity method		17,130		15,982	96,533		52,523
Other income (loss)		1,338		(726)	3,550		2,461
Corporate expenses		(15,066)	[1]	(13,244)	(47,911)	[1]	(43,330)	[1]
Transaction costs and other		(1,995)	[1]	(1,091)	(5,363)	[1]	(8,829)	[1]
Amortization of intangible assets		(20,003)		(26,315)	(60,214)		(79,523)
Interest expense		(31,328)		(29,730)	(89,673)		(90,710)
Net foreign exchange gains (losses)		33,124		10,838	31,697		44,823
Income before income taxes		437,305		282,122	1,509,006		750,436
Income tax expense		(38,116)		(33,356)	(128,474)		(78,939)
Net income		399,189		248,766	1,380,532		671,497
Dividends attributable to redeemable noncontrolling interests		(6,600)		(4,599)	(15,778)		(13,769)
Amounts attributable to non-redeemable noncontrolling interests		(136)		(16,759)	(54,819)		(36,251)
Net income available to Arch		392,453		227,408	1,309,935		621,477
Preferred dividends		(10,403)		(10,402)	(31,209)		(31,242)
Loss on redemption of preferred shares		0		0	0		(2,710)
Net income available to Arch common shareholders		$ 382,050		$ 217,006	$ 1,278,726		$ 587,525
Underwriting Ratios
Loss ratio		55.80%		54.20%	53.60%		53.40%
Acquisition expense ratio		14.70%		15.60%	14.50%		15.40%
Other operating expense ratio		13.70%		12.50%	14.00%		13.30%
Combined ratio		84.20%		82.30%	82.10%		82.10%
Goodwill and intangible assets		$ 624,500		$ 566,662	$ 624,500		$ 566,662		$ 634,920
Other
Segment Reporting Information [Line Items]
Number of segments | segment					2
Gross premiums written	[2]	249,960		185,033	$ 598,627		574,078
Premiums ceded		(94,208)		(33,356)	(178,118)		(102,263)
Net premiums written		155,752		151,677	420,509		471,815
Change in unearned premiums		(29,920)		(16,054)	2,735		(39,926)
Net premiums earned		125,832		135,623	423,244		431,889
Other underwriting income		579		703	1,844		2,092
Losses and loss adjustment expenses		(96,214)		(96,957)	(318,480)		(312,087)
Acquisition expenses, net		(23,072)		(29,619)	(81,654)		(95,229)
Other operating expenses		(11,568)		(9,959)	(39,368)		(27,752)
Underwriting income (loss)		(4,443)		(209)	(14,414)		(1,087)
Net investment income		34,614		29,696	102,314		84,084
Net realized gains (losses)		(18,659)		(4,695)	6,167		(20,900)
Net impairment losses recognized in earnings		0		0	0		0
Equity in net income of investment funds accounted for using the equity method		0		0	0		0
Other income (loss)		0		0	0		0
Corporate expenses		0	[1]	0	0	[1]	0	[1]
Transaction costs and other		0	[1]	0	0	[1]	0	[1]
Amortization of intangible assets		0		0	0		0
Interest expense		(8,091)		(5,064)	(19,579)		(14,079)
Net foreign exchange gains (losses)		3,330		3,708	2,918		6,521
Income before income taxes		6,751		23,436	77,406		54,539
Income tax expense		0		0	(20)		(27)
Net income		6,751		23,436	77,386		54,512
Dividends attributable to redeemable noncontrolling interests		(6,600)		(4,599)	(15,778)		(13,769)
Amounts attributable to non-redeemable noncontrolling interests		(136)		(16,759)	(54,819)		(36,251)
Net income available to Arch		15		2,078	6,789		4,492
Preferred dividends		0		0	0		0
Loss on redemption of preferred shares							0
Net income available to Arch common shareholders		$ 15		$ 2,078	$ 6,789		$ 4,492
Underwriting Ratios
Loss ratio		76.50%		71.50%	75.20%		72.30%
Acquisition expense ratio		18.30%		21.80%	19.30%		22.00%
Other operating expense ratio		9.20%		7.30%	9.30%		6.40%
Combined ratio		104.00%		100.60%	103.80%		100.70%
Goodwill and intangible assets		$ 7,650		$ 7,650	$ 7,650		$ 7,650
Sub-Total
Segment Reporting Information [Line Items]
Number of segments | segment					3
Gross premiums written	[2]	2,043,292		1,622,532	$ 5,853,574		4,935,339
Premiums ceded		(585,587)		(440,656)	(1,690,469)		(1,362,161)
Net premiums written		1,457,705		1,181,876	4,163,105		3,573,178
Change in unearned premiums		(145,514)		(26,621)	(315,733)		(142,527)
Net premiums earned		1,312,191		1,155,255	3,847,372		3,430,651
Other underwriting income		2,747		5,120	16,260		12,954
Losses and loss adjustment expenses		(706,241)		(602,463)	(1,970,050)		(1,750,346)
Acquisition expenses, net		(188,048)		(171,983)	(537,403)		(500,587)
Other operating expenses		(184,944)		(151,139)	(557,221)		(484,542)
Underwriting income (loss)		235,705		234,790	798,958		708,130
Net investment income		126,874		114,328	371,161		322,332
Net realized gains (losses)		81,177		(47,010)	318,722		(218,414)
Net impairment losses recognized in earnings		(1,163)		(492)	(2,521)		(1,124)
Equity in net income of investment funds accounted for using the equity method		17,130		15,982	96,533		52,523
Other income (loss)		1,338		(726)	3,550		2,461
Corporate expenses		(15,066)	[1]	(13,244)	(47,911)	[1]	(43,330)	[1]
Transaction costs and other		(1,995)	[1]	(1,091)	(5,363)	[1]	(8,829)	[1]
Amortization of intangible assets		(20,003)		(26,315)	(60,214)		(79,523)
Interest expense		(23,237)		(24,666)	(70,094)		(76,631)
Net foreign exchange gains (losses)		29,794		7,130	28,779		38,302
Income before income taxes		430,554		258,686	1,431,600		695,897
Income tax expense		(38,116)		(33,356)	(128,454)		(78,912)
Net income		392,438		225,330	1,303,146		616,985
Dividends attributable to redeemable noncontrolling interests		0		0	0		0
Amounts attributable to non-redeemable noncontrolling interests		0		0	0		0
Net income available to Arch		392,438		225,330	1,303,146		616,985
Preferred dividends		(10,403)		(10,402)	(31,209)		(31,242)
Loss on redemption of preferred shares							(2,710)
Net income available to Arch common shareholders		$ 382,035		$ 214,928	$ 1,271,937		$ 583,033
Underwriting Ratios
Loss ratio		53.80%		52.10%	51.20%		51.00%
Acquisition expense ratio		14.30%		14.90%	14.00%		14.60%
Other operating expense ratio		14.10%		13.10%	14.50%		14.10%
Combined ratio		82.20%		80.10%	79.70%		79.70%
Goodwill and intangible assets		$ 616,850		$ 559,012	$ 616,850		$ 559,012
Sub-Total | Insurance
Segment Reporting Information [Line Items]
Gross premiums written	[2]	1,005,874		836,820	2,867,753		2,429,570
Premiums ceded		(302,034)		(259,968)	(914,751)		(752,413)
Net premiums written		703,840		576,852	1,953,002		1,677,157
Change in unearned premiums		(98,504)		(15,794)	(201,719)		(30,913)
Net premiums earned		605,336		561,058	1,751,283		1,646,244
Other underwriting income		0		0	0		0
Losses and loss adjustment expenses		(422,782)		(409,435)	(1,168,677)		(1,120,630)
Acquisition expenses, net		(91,259)		(88,255)	(265,177)		(264,094)
Other operating expenses		(115,408)		(90,081)	(338,327)		(274,735)
Underwriting income (loss)		$ (24,113)		$ (26,713)	$ (20,898)		$ (13,215)
Underwriting Ratios
Loss ratio		69.80%		73.00%	66.70%		68.10%
Acquisition expense ratio		15.10%		15.70%	15.10%		16.00%
Other operating expense ratio		19.10%		16.10%	19.30%		16.70%
Combined ratio		104.00%		104.80%	101.10%		100.80%
Goodwill and intangible assets		$ 158,990		$ 20,141	$ 158,990		$ 20,141
Sub-Total | Reinsurance
Segment Reporting Information [Line Items]
Gross premiums written	[2]	662,572		435,396	1,890,974		1,503,206
Premiums ceded		(226,096)		(123,705)	(627,120)		(455,682)
Net premiums written		436,476		311,691	1,263,854		1,047,524
Change in unearned premiums		(72,621)		(18,418)	(186,450)		(134,761)
Net premiums earned		363,855		293,273	1,077,404		912,763
Other underwriting income		(1,208)		1,387	4,393		2,490
Losses and loss adjustment expenses		(270,379)		(183,413)	(751,147)		(555,044)
Acquisition expenses, net		(62,393)		(50,367)	(173,504)		(148,828)
Other operating expenses		(32,533)		(29,936)	(102,197)		(101,185)
Underwriting income (loss)		$ (2,658)		$ 30,944	$ 54,949		$ 110,196
Underwriting Ratios
Loss ratio		74.30%		62.50%	69.70%		60.80%
Acquisition expense ratio		17.10%		17.20%	16.10%		16.30%
Other operating expense ratio		8.90%		10.20%	9.50%		11.10%
Combined ratio		100.30%		89.90%	95.30%		88.20%
Goodwill and intangible assets		$ 0		$ 0	$ 0		$ 0
Sub-Total | Mortgage
Segment Reporting Information [Line Items]
Gross premiums written	[2]	375,092		350,559	1,095,607		1,002,727
Premiums ceded		(57,703)		(57,226)	(149,358)		(154,230)
Net premiums written		317,389		293,333	946,249		848,497
Change in unearned premiums		25,611		7,591	72,436		23,147
Net premiums earned		343,000		300,924	1,018,685		871,644
Other underwriting income		3,955		3,733	11,867		10,464
Losses and loss adjustment expenses		(13,080)		(9,615)	(50,226)		(74,672)
Acquisition expenses, net		(34,396)		(33,361)	(98,722)		(87,665)
Other operating expenses		(37,003)		(31,122)	(116,697)		(108,622)
Underwriting income (loss)		$ 262,476		$ 230,559	$ 764,907		$ 611,149
Underwriting Ratios
Loss ratio		3.80%		3.20%	4.90%		8.60%
Acquisition expense ratio		10.00%		11.10%	9.70%		10.10%
Other operating expense ratio		10.80%		10.30%	11.50%		12.50%
Combined ratio		24.60%		24.60%	26.10%		31.20%
Goodwill and intangible assets		$ 457,860		$ 538,871	$ 457,860		$ 538,871
[1]	Certain expenses have been excluded from ‘corporate expenses’ and reflected in ‘transaction costs and other.’
[2]	Certain amounts included in the gross premiums written of each segment are related to intersegment transactions. Accordingly, the sum of gross premiums written for each segment does not agree to the total gross premiums written as shown in the table above due to the elimination of intersegment transactions in the total.

Reserve for Losses and Loss A_3

Reserve for Losses and Loss Adjustment Expenses - Reconciliation of beginning and ending balances of losses and loss adjustment reserves (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2019		Sep. 30, 2018		Sep. 30, 2019	Sep. 30, 2018
Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract]
Reserve for losses and loss adjustment expenses at beginning of period	$ 12,230,316		$ 11,424,337		$ 11,853,297	$ 11,383,792
Unpaid losses and loss adjustment expenses recoverable	3,024,797		2,651,749		2,814,291	2,464,910
Net reserve for losses and loss adjustment expenses at beginning of period	9,205,519		8,772,588		9,039,006	8,918,882
Net incurred losses and loss adjustment expenses relating to losses occurring in:
Current year	855,352		779,043		2,419,044	2,257,670
Prior years	(52,897)		(79,623)		(130,514)	(195,237)
Total net incurred losses and loss adjustment expenses	802,455		699,420		2,288,530	2,062,433
Retroactive reinsurance transaction	0	[1]	0	[1]	(225,500)	(420,404)
Net foreign exchange (gains) losses	(73,200)		(33,783)		(74,981)	(110,061)
Net paid losses and loss adjustment expenses relating to losses occurring in:
Current year	(175,611)		(149,999)		(301,099)	(245,021)
Prior years	(399,948)		(396,695)		(1,366,741)	(1,314,298)
Total net paid losses and loss adjustment expenses	(575,559)		(546,694)		(1,667,840)	(1,559,319)
Net reserve for losses and loss adjustment expenses at end of period	9,359,215		8,891,531		9,359,215	8,891,531
Unpaid losses and loss adjustment expenses recoverable	3,030,169		2,662,790		3,030,169	2,662,790
Reserve for losses and loss adjustment expenses at end of period	$ 12,389,384		$ 11,554,321		$ 12,389,384	$ 11,554,321
[1]	During the 2019 first quarter and 2018 second quarter, a subsidiary of the Company entered into two separate retroactive reinsurance transactions with third party reinsurers to reinsure run-off liabilities associated with certain U.S. insurance exposures.

Reserve for Losses and Loss A_4

Reserve for Losses and Loss Adjustment Expenses - Prior year development (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ 52,897	$ 79,623	$ 130,514	$ 195,237
Underwriting segments | Insurance
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ 4,400	$ 5,900	$ 11,400	$ 14,100
Percentage of prior year development	0.70%	1.10%	0.70%	0.90%
Underwriting segments | Insurance | Short Tailed Lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ 24,800	$ 14,300	$ 42,600	$ 37,000
Underwriting segments | Insurance | Medium Tailed Lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development				(39,300)
Underwriting segments | Insurance | Medium Tailed Lines | Other specialty lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development				26,200
Underwriting segments | Insurance | Medium Tailed Lines | Programs
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development				(23,400)
Underwriting segments | Insurance | Medium Tailed Lines | Contract binding
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development				(42,100)
Underwriting segments | Insurance | Medium Tailed Lines | Other product lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development			9,000
Underwriting segments | Insurance | Short Tailed And Medium Tailed Lines | Other specialty lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development		8,000
Underwriting segments | Insurance | Medium Tailed And Long Tailed Lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(20,400)	(8,400)	(31,200)
Underwriting segments | Insurance | Medium Tailed And Long Tailed Lines | Casualty
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(4,900)
Underwriting segments | Insurance | Medium Tailed And Long Tailed Lines | Programs
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(4,200)		(27,400)
Underwriting segments | Insurance | Medium Tailed And Long Tailed Lines | Contract binding
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development		(16,400)	(12,800)
Underwriting segments | Insurance | Medium Tailed And Long Tailed Lines | Executive assurance
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(6,300)
Underwriting segments | Insurance | Medium Tailed And Long Tailed Lines | Healthcare
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(3,800)
Underwriting segments | Insurance | Long Tailed Lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development				16,400
Underwriting segments | Insurance | Long Tailed Lines | Executive assurance
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development				8,000
Underwriting segments | Insurance | Long Tailed Lines | Healthcare
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development				8,100
Underwriting segments | Reinsurance
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ 15,300	$ 34,300	$ 26,300	$ 103,900
Percentage of prior year development	4.20%	11.70%	2.40%	11.40%
Underwriting segments | Reinsurance | Short Tailed Lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development		$ 26,500		$ 77,600
Underwriting segments | Reinsurance | Short Tailed Lines | Property catastrophe and property other than property catastrophe
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development		15,900	$ 9,500	56,400
Underwriting segments | Reinsurance | Short Tailed Lines | Other specialty lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development		10,300	22,600	10,700
Underwriting segments | Reinsurance | Medium Tailed Lines | Marine and aviation
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development			10,400
Underwriting segments | Reinsurance | Short Tailed And Medium Tailed Lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ 35,200		37,100
Underwriting segments | Reinsurance | Short Tailed And Medium Tailed Lines | Property catastrophe and property other than property catastrophe
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	26,500
Underwriting segments | Reinsurance | Medium Tailed And Long Tailed Lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development		7,800		26,300
Underwriting segments | Reinsurance | Medium Tailed And Long Tailed Lines | Casualty
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development		7,900		16,000
Underwriting segments | Reinsurance | Medium Tailed And Long Tailed Lines | Marine and aviation
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development				10,800
Underwriting segments | Reinsurance | Long Tailed Lines
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	(19,900)		(10,800)
Underwriting segments | Mortgage
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ 33,000	$ 38,600	$ 92,500	$ 74,900
Percentage of prior year development	9.60%	12.80%	9.10%	8.60%
Underwriting segments | Other
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior year development	$ 200	$ 700	$ 300	$ 2,300

Investment Information - Summar

Investment Information - Summary of available for sale securities (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2019	Dec. 31, 2018
Available for sale securities:
Estimated Fair Value		$ 17,632,307	$ 15,908,390
Gross Unrealized Gains		410,779	76,259
Gross Unrealized Losses		(85,689)	(205,900)
Cost or Amortized Cost		17,307,217	16,038,031
OTTI Unrealized Losses		(6)	(75)
Fixed maturities
Available for sale securities:
Estimated Fair Value		16,880,318	14,952,510
Gross Unrealized Gains	[1]	410,552	76,223
Gross Unrealized Losses	[1]	(85,244)	(205,506)
Cost or Amortized Cost	[1]	16,555,010	15,081,793
OTTI Unrealized Losses	[1],[2]	(6)	(75)
Fixed maturities | Corporate bonds
Available for sale securities:
Estimated Fair Value		6,269,993	5,537,548
Gross Unrealized Gains	[1]	198,742	14,476
Gross Unrealized Losses	[1]	(18,420)	(105,428)
Cost or Amortized Cost	[1]	6,089,671	5,628,500
OTTI Unrealized Losses	[1],[2]	0	(69)
Fixed maturities | Mortgage backed securities
Available for sale securities:
Estimated Fair Value		544,033	541,193
Gross Unrealized Gains	[1]	11,185	3,991
Gross Unrealized Losses	[1]	(918)	(3,216)
Cost or Amortized Cost	[1]	533,766	540,418
OTTI Unrealized Losses	[1],[2]	(6)	(6)
Fixed maturities | Municipal bonds
Available for sale securities:
Estimated Fair Value		653,346	1,013,395
Gross Unrealized Gains	[1]	27,095	5,380
Gross Unrealized Losses	[1]	(379)	(11,891)
Cost or Amortized Cost	[1]	626,630	1,019,906
OTTI Unrealized Losses	[1],[2]	0	0
Fixed maturities | Commercial mortgage backed securities
Available for sale securities:
Estimated Fair Value		754,306	729,442
Gross Unrealized Gains	[1]	27,523	2,650
Gross Unrealized Losses	[1]	(158)	(10,751)
Cost or Amortized Cost	[1]	726,941	737,543
OTTI Unrealized Losses	[1],[2]	0	0
Fixed maturities | US government and government agencies
Available for sale securities:
Estimated Fair Value		5,127,290	3,758,698
Gross Unrealized Gains	[1]	67,957	27,189
Gross Unrealized Losses	[1]	(6,671)	(8,474)
Cost or Amortized Cost	[1]	5,066,004	3,739,983
OTTI Unrealized Losses	[1],[2]	0	0
Fixed maturities | Non-US government securities
Available for sale securities:
Estimated Fair Value		1,873,856	1,771,338
Gross Unrealized Gains	[1]	48,212	14,477
Gross Unrealized Losses	[1]	(52,767)	(50,948)
Cost or Amortized Cost	[1]	1,878,411	1,807,809
OTTI Unrealized Losses	[1],[2]	0	0
Fixed maturities | Asset backed securities
Available for sale securities:
Estimated Fair Value		1,657,494	1,600,896
Gross Unrealized Gains	[1]	29,838	8,060
Gross Unrealized Losses	[1]	(5,931)	(14,798)
Cost or Amortized Cost	[1]	1,633,587	1,607,634
OTTI Unrealized Losses	[1],[2]	0	0
Short-term investments
Available for sale securities:
Estimated Fair Value		751,989	955,880
Gross Unrealized Gains		227	36
Gross Unrealized Losses		(445)	(394)
Cost or Amortized Cost		752,207	956,238
OTTI Unrealized Losses	[2]	$ 0	$ 0
[1]	In securities lending transactions, the Company receives collateral in excess of the fair value of the fixed maturities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See “—Securities Lending Agreements.”
[2]	Represents the total other-than-temporary impairments (“OTTI”) recognized in accumulated other comprehensive income (“AOCI”). It does not include the change in fair value subsequent to the impairment measurement date. At September 30, 2019 the net unrealized loss related to securities for which a non-credit OTTI was recognized in AOCI was $0.01 million , compared to net unrealized loss of $0.04 million at December 31, 2018

Investment Information - Aging

Investment Information - Aging of available for sale securities in an unrealized loss position (Details) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Available for sale securities:
Estimated Fair Value - Less than 12 Months		$ 3,951,908	$ 5,843,772
Gross Unrealized Losses - Less than 12 Months		(75,881)	(120,614)
Estimated Fair Value - 12 Months or More		259,794	3,094,853
Gross Unrealized Losses - 12 Months or More		(9,808)	(85,286)
Estimated Fair Value - Total		4,211,702	8,938,625
Gross Unrealized Losses - Total		(85,689)	(205,900)
Fixed maturities
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	3,908,901	5,720,894
Gross Unrealized Losses - Less than 12 Months	[1]	(75,436)	(120,220)
Estimated Fair Value - 12 Months or More	[1]	259,794	3,094,853
Gross Unrealized Losses - 12 Months or More	[1]	(9,808)	(85,286)
Estimated Fair Value - Total	[1]	4,168,695	8,815,747
Gross Unrealized Losses - Total	[1]	(85,244)	(205,506)
Fixed maturities | Corporate bonds
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	538,471	2,983,195
Gross Unrealized Losses - Less than 12 Months	[1]	(11,128)	(68,910)
Estimated Fair Value - 12 Months or More	[1]	113,987	1,234,865
Gross Unrealized Losses - 12 Months or More	[1]	(7,292)	(36,518)
Estimated Fair Value - Total	[1]	652,458	4,218,060
Gross Unrealized Losses - Total	[1]	(18,420)	(105,428)
Fixed maturities | Mortgage backed securities
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	97,288	84,296
Gross Unrealized Losses - Less than 12 Months	[1]	(905)	(695)
Estimated Fair Value - 12 Months or More	[1]	200	109,009
Gross Unrealized Losses - 12 Months or More	[1]	(13)	(2,521)
Estimated Fair Value - Total	[1]	97,488	193,305
Gross Unrealized Losses - Total	[1]	(918)	(3,216)
Fixed maturities | Municipal bonds
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	43,627	233,081
Gross Unrealized Losses - Less than 12 Months	[1]	(379)	(2,074)
Estimated Fair Value - 12 Months or More	[1]	0	408,155
Gross Unrealized Losses - 12 Months or More	[1]	0	(9,817)
Estimated Fair Value - Total	[1]	43,627	641,236
Gross Unrealized Losses - Total	[1]	(379)	(11,891)
Fixed maturities | Commercial mortgage backed securities
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	47,219	223,341
Gross Unrealized Losses - Less than 12 Months	[1]	(151)	(2,831)
Estimated Fair Value - 12 Months or More	[1]	1,872	193,956
Gross Unrealized Losses - 12 Months or More	[1]	(7)	(7,920)
Estimated Fair Value - Total	[1]	49,091	417,297
Gross Unrealized Losses - Total	[1]	(158)	(10,751)
Fixed maturities | US government and government agencies
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	1,592,232	635,049
Gross Unrealized Losses - Less than 12 Months	[1]	(6,531)	(1,354)
Estimated Fair Value - 12 Months or More	[1]	47,416	391,102
Gross Unrealized Losses - 12 Months or More	[1]	(140)	(7,120)
Estimated Fair Value - Total	[1]	1,639,648	1,026,151
Gross Unrealized Losses - Total	[1]	(6,671)	(8,474)
Fixed maturities | Non-US government securities
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	1,214,128	1,028,340
Gross Unrealized Losses - Less than 12 Months	[1]	(51,742)	(35,524)
Estimated Fair Value - 12 Months or More	[1]	47,576	389,671
Gross Unrealized Losses - 12 Months or More	[1]	(1,025)	(15,424)
Estimated Fair Value - Total	[1]	1,261,704	1,418,011
Gross Unrealized Losses - Total	[1]	(52,767)	(50,948)
Fixed maturities | Asset backed securities
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	375,936	533,592
Gross Unrealized Losses - Less than 12 Months	[1]	(4,600)	(8,832)
Estimated Fair Value - 12 Months or More	[1]	48,743	368,095
Gross Unrealized Losses - 12 Months or More	[1]	(1,331)	(5,966)
Estimated Fair Value - Total	[1]	424,679	901,687
Gross Unrealized Losses - Total	[1]	(5,931)	(14,798)
Short-term investments
Available for sale securities:
Estimated Fair Value - Less than 12 Months		43,007	122,878
Gross Unrealized Losses - Less than 12 Months		(445)	(394)
Estimated Fair Value - 12 Months or More		0	0
Gross Unrealized Losses - 12 Months or More		0	0
Estimated Fair Value - Total		43,007	122,878
Gross Unrealized Losses - Total		$ (445)	$ (394)
[1]	In securities lending transactions, the Company receives collateral in excess of the fair value of the fixed maturities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See “—Securities Lending Agreements.”

Investment Information - Maturi

Investment Information - Maturity profile of available for sale securities) (Details) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Estimated Fair Value:
Estimated fair value		$ 16,470,523	$ 14,699,010
Amortized Cost:
Amortized cost		16,146,333	14,829,902
Fixed maturities
Estimated Fair Value:
Due in one year or less		545,056	276,682
Due after one year through five years		10,096,867	8,666,297
Due after five years through 10 years		3,075,318	2,919,232
Due after 10 years		207,244	218,768
Single maturity date		13,924,485	12,080,979
Estimated fair value	[1]	16,880,318	14,952,510
Amortized Cost:
Due in one year or less		538,903	279,135
Due after one year through five years		9,971,896	8,738,944
Due after five years through 10 years		2,952,478	2,951,582
Due after 10 years		197,439	226,537
Single maturity date		13,660,716	12,196,198
Amortized cost	[1]	16,555,010	15,081,793
Fixed maturities | Mortgage backed securities
Estimated Fair Value:
Securities without single maturity date		544,033	541,193
Amortized Cost:
Securities without single maturity date		533,766	540,418
Fixed maturities | Commercial mortgage backed securities
Estimated Fair Value:
Securities without single maturity date		754,306	729,442
Amortized Cost:
Securities without single maturity date		726,941	737,543
Fixed maturities | Asset backed securities
Estimated Fair Value:
Securities without single maturity date		1,657,494	1,600,896
Amortized Cost:
Securities without single maturity date		$ 1,633,587	$ 1,607,634
[1]	In securities lending transactions, the Company receives collateral in excess of the fair value of the securities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See “—Securities Lending Agreements.”

Investment Information - Securi

Investment Information - Securities lending agreements (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Disclosure Investment Information [Abstract]
Fair value of cash collateral received on securities lending	$ 12,000	$ 19,000
Fair value of non-cash collateral received on securities lending	418,200	255,100
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	430,255	274,125
Gross amount of recognized liabilities for securities lending in offsetting disclosure in note 8	0	0
Amounts related to securities lending not included in offsetting disclosure in note 8	430,255	274,125
US government and government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	414,520	251,859
Corporate bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	4,820	7,129
Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	10,915	15,137
Overnight and continuous
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	273,714	241,542
Overnight and continuous | US government and government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	257,979	219,276
Overnight and continuous | Corporate bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	4,820	7,129
Overnight and continuous | Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	10,915	15,137
Less than 30 days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	0	0
Less than 30 days | US government and government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	0	0
Less than 30 days | Corporate bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	0	0
Less than 30 days | Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	0	0
30 - 90 days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	156,541	32,583
30 - 90 days | US government and government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	156,541	32,583
30 - 90 days | Corporate bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	0	0
30 - 90 days | Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	0	0
90 days or more
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	0	0
90 days or more | US government and government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	0	0
90 days or more | Corporate bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	0	0
90 days or more | Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	$ 0	$ 0

Investment Information - Other

Investment Information - Other investments (Details) - Fair value option - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Other Investments [Line Items]
Other investments	$ 2,440,120	$ 2,311,939
Term loan investments
Schedule Of Other Investments [Line Items]
Other investments	1,330,886	1,282,287
Other investments par	1,434,328	1,369,216
Lending
Schedule Of Other Investments [Line Items]
Other investments	624,699	524,112
Credit related funds
Schedule Of Other Investments [Line Items]
Other investments	165,444	202,123
Energy
Schedule Of Other Investments [Line Items]
Other investments	113,791	117,509
Investment grade fixed income
Schedule Of Other Investments [Line Items]
Other investments	83,649	101,902
Infrastructure
Schedule Of Other Investments [Line Items]
Other investments	49,602	45,371
Private equity
Schedule Of Other Investments [Line Items]
Other investments	54,609	24,383
Real estate
Schedule Of Other Investments [Line Items]
Other investments	$ 17,440	$ 14,252

Investment Information - Equity

Investment Information - Equity method investments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	$ 1,575,832	$ 1,493,791
Credit related funds
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	428,353	429,402
Equity securities
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	284,465	375,273
Real estate
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	265,502	232,647
Lending
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	200,112	125,041
Private equity
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	141,343	114,019
Infrastructure
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	149,005	113,748
Energy
Schedule of Equity Method Investments [Line Items]
Investments accounted for using the equity method	$ 107,052	$ 103,661

Investment Information - Fair v

Investment Information - Fair value option (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Option, Quantitative Disclosures [Line Items]
Investments accounted for using the fair value option	$ 3,838,243	$ 3,983,571
Fixed maturities
Fair Value, Option, Quantitative Disclosures [Line Items]
Investments accounted for using the fair value option	908,802	1,245,562
Other investments
Fair Value, Option, Quantitative Disclosures [Line Items]
Investments accounted for using the fair value option	2,440,120	2,311,939
Short-term investments
Fair Value, Option, Quantitative Disclosures [Line Items]
Investments accounted for using the fair value option	390,980	322,177
Equity securities
Fair Value, Option, Quantitative Disclosures [Line Items]
Investments accounted for using the fair value option	$ 98,341	$ 103,893

Investment Information - Limite

Investment Information - Limited partnership interests (Details) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Maximum Exposure to Loss		$ 1,765,018	$ 1,656,189
Aggregate unfunded commitments		1,900,000	1,770,000
Equity method investments
Schedule of Equity Method Investments [Line Items]
Maximum Exposure to Loss	[1]	1,575,832	1,493,791
Aggregate unfunded commitments		1,440,000	1,220,000
Fair value option
Schedule of Equity Method Investments [Line Items]
Maximum Exposure to Loss	[2]	189,186	162,398
Aggregate unfunded commitments		$ 51,100	$ 117,500
[1]	Aggregate unfunded commitments were $1.44 billion at September 30, 2019 , compared to $1.22 billion at December 31, 2018 .
[2]	Aggregate unfunded commitments were $51.1 million at September 30, 2019 , compared to $117.5 million at December 31, 2018 .

Investment Information - Net in

Investment Information - Net investment income (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net investment income:
Gross investment income		$ 181,655	$ 167,326	$ 540,931	$ 482,462
Investment expenses		(20,167)	(23,302)	(67,456)	(76,046)
Net investment income		161,488	144,024	473,475	406,416
Fixed maturities
Net investment income:
Gross investment income		126,889	120,516	381,706	343,513
Term loans
Net investment income:
Gross investment income		24,236	21,903	73,582	62,430
Equity securities
Net investment income:
Gross investment income		3,992	3,165	11,348	10,510
Short-term investments
Net investment income:
Gross investment income		3,834	4,547	11,872	13,799
Other
Net investment income:
Gross investment income	[1]	$ 22,704	$ 17,195	$ 62,423	$ 52,210
[1]	Includes income distributions from investment funds and other items.

Investment Information - Net re

Investment Information - Net realized gains and losses (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net realized gains and losses:
Available for sale securities, gross gains on investment sales		$ 73,685	$ 10,990	$ 192,140	$ 44,732
Available for sale securities, gross losses on investment sales		(30,561)	(34,879)	(77,498)	(175,141)
Net realized gains (losses) on sales during the period		5,217	(2,012)	9,503	(13,298)
Net unrealized gains (losses) on equity securities still held at reporting date		(1,206)	10,798	58,562	(4,063)
Derivative instruments	[1]	42,893	(17,556)	142,730	(23,665)
Other	[2]	1,335	(6,773)	(8,703)	(16,111)
Net realized gains (losses)		62,518	(51,705)	324,889	(239,314)
Fixed maturities
Net realized gains and losses:
Change in fair value of assets and liabilities accounted for using the fair value option		(3,895)	(6,604)	38,682	(47,082)
Other investments
Net realized gains and losses:
Change in fair value of assets and liabilities accounted for using the fair value option		(21,778)	(7,950)	(37,363)	(14,578)
Equity securities
Net realized gains and losses:
Change in fair value of assets and liabilities accounted for using the fair value option		(1,231)	2,752	9,449	10,650
Short-term investments
Net realized gains and losses:
Change in fair value of assets and liabilities accounted for using the fair value option		$ (1,941)	$ (471)	$ (2,613)	$ (758)
[1]	See note 8 for information on the Company’s derivative instruments.
[2]	Includes the re-measurement of contingent consideration liability amounts.

Investment Information - Net im

Investment Information - Net impairment losses recognized in earnings (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	$ (1,163)	$ (492)	$ (2,521)	$ (1,124)
Fixed maturities | Mortgage backed securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	(284)	(73)	(839)	(196)
Fixed maturities | Corporate bonds
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	(666)	(270)	(1,256)	(631)
Fixed maturities | Non-US government securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	0	(149)	0	(149)
Fixed maturities | Asset backed securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	$ (213)	$ 0	$ (426)	$ (148)

Investment Information - Othe_2

Investment Information - Other than temporary impairments rollforward (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Rollforward:
Balance at start of period	$ 346	$ 698	$ 637	$ 767
Credit loss impairments recognized on securities not previously impaired	0	0	0	0
Credit loss impairments recognized on securities previously impaired	0	0	0	0
Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security	0	0	0	0
Reductions for securities sold during the period	0	(47)	(291)	(116)
Balance at end of period	$ 346	$ 651	$ 346	$ 651

Investment Information - Restri

Investment Information - Restricted assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Restricted Assets [Line Items]
Restricted assets	$ 8,095,051	$ 7,553,903
Collateral or guarantees - affiliated transactions
Restricted Assets [Line Items]
Restricted assets	4,629,369	4,623,483
Collateral or guarantees - third party agreements
Restricted Assets [Line Items]
Restricted assets	2,605,587	2,181,682
Deposits with US regulatory authorities
Restricted Assets [Line Items]
Restricted assets	788,295	689,114
Deposits with non-US regulatory authorities
Restricted Assets [Line Items]
Restricted assets	71,800	59,624
Watford Holdings Ltd
Restricted Assets [Line Items]
Assets pledged as collateral	$ 1,060,000	$ 1,300,000

Investment Information - Cash a

Investment Information - Cash and restricted cash (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Disclosure Investment Information [Abstract]
Cash	$ 880,099	$ 646,556
Restricted cash (included in ‘other assets’)	82,376	78,087
Cash and restricted cash	$ 962,475	$ 724,643	$ 709,819	$ 727,284

Investment Information - Narrat

Investment Information - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019USD ($)lots	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)lots	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)lots
Narrative items:
Investable assets	$ 24,300,000		$ 24,300,000
Equity in net income of investment funds accounted for using the equity method	17,130	$ 15,982	96,533	$ 52,523
OTTI unrealized (losses) gains at current fair value	$ (10)		$ (10)		$ (40)
Continuous unrealized loss, qualitative disclosures:
Number of positions in an unrealized loss position (lots) | lots	1,980		1,980		5,870
Total number of positions (lots) | lots	9,260		9,260		8,450
Largest single loss	$ 3,000		$ 3,000		$ 2,600
Equity securities, at fair value	550,485		550,485		338,899
OTTI unrealized losses (gains)			$ 6		$ 75
Minimum
Narrative items:
Time lag for reporting			1 month
Maximum
Narrative items:
Time lag for reporting			3 months
Underwriting segments
Narrative items:
Investable assets	21,570,000		$ 21,570,000
Equity in net income of investment funds accounted for using the equity method	17,130	15,982	96,533	52,523
Other
Narrative items:
Investable assets	2,730,000		2,730,000
Equity in net income of investment funds accounted for using the equity method	$ 0	$ 0	$ 0	$ 0

Fair Value - Fair Value Hierarc

Fair Value - Fair Value Hierarchy (Details) - Recurring - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		$ 6,700,978	$ 5,332,640
Liabilities measured at fair value		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Contingent consideration liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Securities sold but not yet purchased
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value	[1]	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Derivative instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	5,005,512	3,657,181
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | Mortgage backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | Commercial mortgage backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | US government and government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	5,005,512	3,657,181
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | Non-US government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed maturities | Asset backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		514,380	321,927
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		720,518	875,881
Quoted Prices in Active Markets for Identical Assets (Level 1) | Derivative instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		460,568	477,651
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value option | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value option | Mortgage backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value option | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value option | US government and government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		1,886	111,138
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value option | Non-US government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value option | Asset backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value option | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		376,033	278,579
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value option | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		41,333	48,827
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair value option | Other investments fair value option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		41,316	39,107
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		14,139,340	13,852,372
Liabilities measured at fair value		(119,476)	(28,454)
Significant Other Observable Inputs (Level 2) | Contingent consideration liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value		0	0
Significant Other Observable Inputs (Level 2) | Securities sold but not yet purchased
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value	[1]	(65,736)	(7,790)
Significant Other Observable Inputs (Level 2) | Derivative instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value		(53,740)	(20,664)
Significant Other Observable Inputs (Level 2) | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	11,860,340	11,286,875
Significant Other Observable Inputs (Level 2) | Fixed maturities | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	6,261,248	5,529,407
Significant Other Observable Inputs (Level 2) | Fixed maturities | Mortgage backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	543,761	540,884
Significant Other Observable Inputs (Level 2) | Fixed maturities | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	653,346	1,013,395
Significant Other Observable Inputs (Level 2) | Fixed maturities | Commercial mortgage backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	754,306	729,438
Significant Other Observable Inputs (Level 2) | Fixed maturities | US government and government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	121,778	101,517
Significant Other Observable Inputs (Level 2) | Fixed maturities | Non-US government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	1,873,856	1,771,338
Significant Other Observable Inputs (Level 2) | Fixed maturities | Asset backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	1,652,045	1,600,896
Significant Other Observable Inputs (Level 2) | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		11,402	31,867
Significant Other Observable Inputs (Level 2) | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		31,471	79,999
Significant Other Observable Inputs (Level 2) | Derivative instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		51,647	73,893
Significant Other Observable Inputs (Level 2) | Fair value option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		2,184,480	2,379,738
Significant Other Observable Inputs (Level 2) | Fair value option | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		597,000	846,827
Significant Other Observable Inputs (Level 2) | Fair value option | Mortgage backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		15,512	16,731
Significant Other Observable Inputs (Level 2) | Fair value option | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		1,140	7,144
Significant Other Observable Inputs (Level 2) | Fair value option | US government and government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		110	108
Significant Other Observable Inputs (Level 2) | Fair value option | Non-US government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		61,755	79,066
Significant Other Observable Inputs (Level 2) | Fair value option | Asset backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		208,620	178,790
Significant Other Observable Inputs (Level 2) | Fair value option | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		14,947	43,598
Significant Other Observable Inputs (Level 2) | Fair value option | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		735	55,066
Significant Other Observable Inputs (Level 2) | Fair value option | Other investments fair value option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		1,284,661	1,152,408
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		214,283	76,917
Liabilities measured at fair value		(7,344)	(66,665)
Significant Unobservable Inputs (Level 3) | Contingent consideration liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value		(7,344)	(66,665)
Significant Unobservable Inputs (Level 3) | Securities sold but not yet purchased
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value	[1]	0	0
Significant Unobservable Inputs (Level 3) | Derivative instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value		0	0
Significant Unobservable Inputs (Level 3) | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	14,466	8,454
Significant Unobservable Inputs (Level 3) | Fixed maturities | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	8,745	8,141
Significant Unobservable Inputs (Level 3) | Fixed maturities | Mortgage backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	272	309
Significant Unobservable Inputs (Level 3) | Fixed maturities | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	0	0
Significant Unobservable Inputs (Level 3) | Fixed maturities | Commercial mortgage backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	0	4
Significant Unobservable Inputs (Level 3) | Fixed maturities | US government and government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	0	0
Significant Unobservable Inputs (Level 3) | Fixed maturities | Non-US government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	0	0
Significant Unobservable Inputs (Level 3) | Fixed maturities | Asset backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[2]	5,449	0
Significant Unobservable Inputs (Level 3) | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		35,323	0
Significant Unobservable Inputs (Level 3) | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Significant Unobservable Inputs (Level 3) | Derivative instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Significant Unobservable Inputs (Level 3) | Fair value option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		164,494	68,463
Significant Unobservable Inputs (Level 3) | Fair value option | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		22,779	5,758
Significant Unobservable Inputs (Level 3) | Fair value option | Mortgage backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Significant Unobservable Inputs (Level 3) | Fair value option | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Significant Unobservable Inputs (Level 3) | Fair value option | US government and government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Significant Unobservable Inputs (Level 3) | Fair value option | Non-US government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Significant Unobservable Inputs (Level 3) | Fair value option | Asset backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Significant Unobservable Inputs (Level 3) | Fair value option | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Significant Unobservable Inputs (Level 3) | Fair value option | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		56,272	0
Significant Unobservable Inputs (Level 3) | Fair value option | Other investments fair value option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		85,443	62,705
Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		22,083,301	20,319,648
Liabilities measured at fair value		(126,820)	(95,119)
Estimated Fair Value | Contingent consideration liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value		(7,344)	(66,665)
Estimated Fair Value | Securities sold but not yet purchased
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value	[1]	(65,736)	(7,790)
Estimated Fair Value | Derivative instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value		(53,740)	(20,664)
Estimated Fair Value | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		16,880,318	14,952,510
Estimated Fair Value | Fixed maturities | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		6,269,993	5,537,548
Estimated Fair Value | Fixed maturities | Mortgage backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		544,033	541,193
Estimated Fair Value | Fixed maturities | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		653,346	1,013,395
Estimated Fair Value | Fixed maturities | Commercial mortgage backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		754,306	729,442
Estimated Fair Value | Fixed maturities | US government and government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		5,127,290	3,758,698
Estimated Fair Value | Fixed maturities | Non-US government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		1,873,856	1,771,338
Estimated Fair Value | Fixed maturities | Asset backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		1,657,494	1,600,896
Estimated Fair Value | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		561,105	353,794
Estimated Fair Value | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		751,989	955,880
Estimated Fair Value | Derivative instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		51,647	73,893
Estimated Fair Value | Fair value option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		3,838,242	3,983,571
Estimated Fair Value | Fair value option | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		619,779	852,585
Estimated Fair Value | Fair value option | Mortgage backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		15,512	16,731
Estimated Fair Value | Fair value option | Municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		1,140	7,144
Estimated Fair Value | Fair value option | US government and government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		1,996	111,246
Estimated Fair Value | Fair value option | Non-US government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		61,755	79,066
Estimated Fair Value | Fair value option | Asset backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		208,620	178,790
Estimated Fair Value | Fair value option | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		390,980	322,177
Estimated Fair Value | Fair value option | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		98,340	103,893
Estimated Fair Value | Fair value option | Other investments fair value option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		1,411,420	1,254,220
Estimated Fair Value | Fair value option | Other investments measured at net asset value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	[3]	$ 1,028,700	$ 1,057,719
[1]	Represents the Company’s obligations to deliver securities that it did not own at the time of sale. Such amounts are included in “other liabilities” on the Company’s consolidated balance sheets.
[2]	In securities lending transactions, the Company receives collateral in excess of the fair value of the securities pledged. For purposes of this table, the Company has excluded the collateral received under securities lending, at fair value and included the securities pledged under securities lending, at fair value. See note 6 , “—Securities Lending Agreements.”
[3]	In accordance with applicable accounting guidance, certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheets.

Fair Value - Rollforward of Lev

Fair Value - Rollforward of Level 3 assets and liabilities (Details) - Recurring - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Contingent consideration liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		$ (7,825)	$ (63,930)	$ (66,665)	$ (60,996)
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	(79)	(1,711)	(1,410)	(4,645)
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0	0	0	0
Purchases, issuances, sales and settlements
Purchases		0	0	0	0
Issuances		0	0	(548)	0
Sales		0	0	0	0
Settlements		560	0	(61,279)	0
Transfers in and/or out of Level 3		0	0	0	0
Balance at end of period		(7,344)	(65,641)	(7,344)	(65,641)
Available for sale | Structured securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	[2]	290	376	313	5,927
Total gains or (losses) (realized/unrealized) - included in earnings	[1],[2]	0	0	1,757	4
Total gains or (losses) (realized/unrealized) - included in other comprehensive income	[2]	0	2	5	(6)
Purchases, issuances, sales and settlements
Purchases	[2]	0	0	0	0
Issuances	[2]	0	0	0	0
Sales	[2]	0	0	(1,757)	(5,003)
Settlements	[2]	(18)	(33)	(46)	(577)
Transfers in and/or out of Level 3	[2]	5,449	0	5,449	0
Balance at end of period	[2]	5,721	345	5,721	345
Available for sale | Corporate bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		7,642	8,773	8,141	9,460
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	0	(1)	0	(1)
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		(301)	(32)	(317)	(200)
Purchases, issuances, sales and settlements
Purchases		0	0	429	393
Issuances		0	0	0	0
Sales		0	0	0	0
Settlements		(456)	(456)	(1,368)	(1,368)
Transfers in and/or out of Level 3		1,860	0	1,860	0
Balance at end of period		8,745	8,284	8,745	8,284
Fair value option | Corporate bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		26,103	11,335	5,758	12,217
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	(1,227)	(503)	(1,566)	(1,115)
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0	0	0	0
Purchases, issuances, sales and settlements
Purchases		0	0	0	0
Issuances		0	0	0	0
Sales		(2,097)	0	(5,332)	0
Settlements		0	(1,226)	0	(1,496)
Transfers in and/or out of Level 3		0	0	23,919	0
Balance at end of period		22,779	9,606	22,779	9,606
Fair value option | Other investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		95,273	58,214	62,705	59,167
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	(411)	(1,459)	(11,727)	(1,838)
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0	0	0	0
Purchases, issuances, sales and settlements
Purchases		3,713	6,250	3,713	6,250
Issuances		0	0	0	0
Sales		(80)	(74)	(228)	(148)
Settlements		0	0	(600)	(500)
Transfers in and/or out of Level 3		(13,052)	0	31,580	0
Balance at end of period		85,443	62,931	85,443	62,931
Fair value option | Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		56,145	0	0	0
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	127	0	127	0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0	0	0	0
Purchases, issuances, sales and settlements
Purchases		0	0	0	0
Issuances		0	0	0	0
Sales		0	0	0	0
Settlements		0	0	0	0
Transfers in and/or out of Level 3		0	0	56,145	0
Balance at end of period		56,272	0	56,272	0
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		51,212	0	0	0
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	(26)	0	(26)	0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0	0	0	0
Purchases, issuances, sales and settlements
Purchases		12,119	0	12,119	0
Issuances		0	0	0	0
Sales		(27,982)	0	(27,982)	0
Settlements		0	0	0	0
Transfers in and/or out of Level 3		0	0	51,212	0
Balance at end of period		$ 35,323	$ 0	$ 35,323	$ 0
[1]	Gains or losses were included in net realized gains (losses).
[2]	Includes asset backed securities, mortgage backed securities and commercial mortgage backed securities.

Fair Value - Narrative (Details

Fair Value - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Total assets and liabilities measured at fair value	$ 22,210,000	$ 20,410,000
Total assets and liabilities measured at fair value priced using non-binding broker quotes	$ 187,900	$ 217,900
Total assets and liabilities measured at fair value priced using non-binding broker quotes (percentage)	0.90%	1.10%
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Senior notes	$ 1,871,386	$ 1,733,528
Variable Interest Entity, Primary Beneficiary | Watford Holdings Ltd
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Senior notes	172,350	0
Recurring | Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers from Level 2 to Level 3	107,400
Recurring | Corporate bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers from Level 2 to Level 3	25,800
Recurring | Fair value option | Other investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers from Level 2 to Level 3	31,600
Recurring | Available for sale | Asset backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers from Level 2 to Level 3	5,500
Arch Capital and Arch-US
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Senior notes	1,870,000	1,730,000
Estimated fair value of senior notes	$ 2,350,000	$ 1,880,000

Derivative Instruments (Details

Derivative Instruments (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Derivative offsetting [Abstract]
Derivative assets subject to master netting agreements		$ 105,500		$ 105,500		$ 80,400
Derivative liabilities subject to master netting agreements		52,700		52,700		18,900
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments	[1]	42,893	$ (17,556)	142,730	$ (23,665)
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Asset derivatives - fair value		106,608		106,608		82,185
Liability derivatives - fair value		(53,740)		(53,740)		(20,664)
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		42,893	(17,556)	142,730	(23,665)
Not Designated as Hedging Instrument [Member] | Futures contracts
Derivative [Line Items]
Net derivatives - notional value	[2],[3]	3,987,260		3,987,260		3,153,518
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		46,194	(15,399)	140,503	(10,609)
Not Designated as Hedging Instrument [Member] | Futures contracts | Other assets
Derivative [Line Items]
Asset derivatives - fair value	[3]	15,148		15,148		51,800
Not Designated as Hedging Instrument [Member] | Futures contracts | Other liabilities
Derivative [Line Items]
Liability derivatives - fair value	[3]	(20,515)		(20,515)		(2,115)
Not Designated as Hedging Instrument [Member] | Foreign currency forward contracts
Derivative [Line Items]
Net derivatives - notional value	[2],[3]	965,348		965,348		1,008,907
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		2,044	(5,458)	(17,030)	(13,074)
Not Designated as Hedging Instrument [Member] | Foreign currency forward contracts | Other assets
Derivative [Line Items]
Asset derivatives - fair value	[3]	5,316		5,316		8,147
Not Designated as Hedging Instrument [Member] | Foreign currency forward contracts | Other liabilities
Derivative [Line Items]
Liability derivatives - fair value	[3]	(8,616)		(8,616)		(7,796)
Not Designated as Hedging Instrument [Member] | TBAs
Derivative [Line Items]
Net derivatives - notional value	[2],[4]	53,229		53,229		8,132
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		269	(3)	507	(100)
Not Designated as Hedging Instrument [Member] | TBAs | Fixed maturities available for sale
Derivative [Line Items]
Asset derivatives - fair value	[4]	54,961		54,961		8,292
Liability derivatives - fair value	[4]	0		0		0
Not Designated as Hedging Instrument [Member] | Other
Derivative [Line Items]
Net derivatives - notional value	[2],[3]	3,983,466		3,983,466		2,213,981
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		(5,614)	$ 3,304	18,750	$ 118
Not Designated as Hedging Instrument [Member] | Other | Other assets
Derivative [Line Items]
Asset derivatives - fair value	[3]	31,183		31,183		13,946
Not Designated as Hedging Instrument [Member] | Other | Other liabilities
Derivative [Line Items]
Liability derivatives - fair value	[3]	$ (24,609)		$ (24,609)		$ (10,753)
[1]	See note 8 for information on the Company’s derivative instruments.
[2]	Represents the absolute notional value of all outstanding contracts, consisting of long and short positions.
[3]	The fair value of asset derivatives are included in ‘other assets’ and the fair value of liability derivatives are included in ‘other liabilities.’
[4]	The fair value of TBAs are included in ‘fixed maturities available for sale, at fair value.’

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Line of Credit Facility [Line Items]
Investment commitments	$ 1,900		$ 1,770
Interest expense on senior notes and other borrowings	68.6	$ 67.6
Watford Holdings Ltd | Letter of credit
Line of Credit Facility [Line Items]
Credit facility, maximum	$ 100

Leases - Additional information

Leases - Additional information (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)
Lessee, Lease, Description [Line Items]
Operating lease costs	$ 7,751	$ 22,611
Cash payments included in the measurement of lease liabilities reported in operating cash flows	8,031	22,616
Right-of-use assets obtained in exchange for new lease liabilities	2,897	7,009
Lease liability	$ 147,325	$ 147,325
Weighted average discount rate	3.90%	3.90%
Weighted average remaining lease term in years	6 years 3 months 18 days	6 years 3 months 18 days
Maximum
Lessee, Lease, Description [Line Items]
Operating lease term	11 years	11 years
Other assets
Lessee, Lease, Description [Line Items]
Right-of-use assets	$ 131,424	$ 131,424
Other liabilities
Lessee, Lease, Description [Line Items]
Lease liability	$ 147,326	$ 147,326

Leases - Contractual maturities

Leases - Contractual maturities and future minimum rental payments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Contractual maturities of operating lease liabilities
2019 (remainder)	$ 1,693
2020	31,541
2021	30,392
2022	27,096
2023	22,290
2024 and thereafter	55,080
Total undiscounted lease liability	168,092
Less: present value adjustment	(20,767)
Operating lease liability	$ 147,325
Future minimum rental commitments:
2019		$ 31,088
2020		30,491
2021		29,351
2022		26,068
2023		21,408
2024 and thereafter		54,745
Total future minimum payments		$ 193,151

Variable Interest Entities an_3

Variable Interest Entities and Noncontrolling Interests - Variable interest entity (Details) - USD ($) $ in Thousands	Jul. 02, 2019	Mar. 31, 2014	Sep. 30, 2019	Sep. 30, 2018
Variable Interest Entity [Line Items]
Net cash used for operating activities			$ 1,543,139	$ 1,120,987
Net cash used for investing activities			(1,250,476)	(390,083)
Net cash provided by financing activities			(46,496)	(736,744)
Variable Interest Entity, Primary Beneficiary | Watford Holdings Ltd
Variable Interest Entity [Line Items]
Initial investment contribution amount		$ 100,000
Number of shares acquired		2,500,000
Ownership percentage		11.00%
Number of shares called by warrants		975,503
Senior notes, face amount	$ 175,000
Senior notes, stated percentage	6.50%
Proceeds from issuance of senior notes	$ 172,400
Senior notes acquired	$ 35,000
Net cash used for operating activities			177,200	174,300
Net cash used for investing activities			(181,200)	(208,300)
Net cash provided by financing activities			$ 22,200	$ (24,200)

Variable Interest Entities an_4

Variable Interest Entities and Noncontrolling Interests - Carrying amount of assets and liabilities of variable interest entity (Details) - USD ($) $ in Thousands		Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Investments accounted for using the fair value option		$ 3,838,243		$ 3,983,571
Fixed maturities available for sale, at fair value		16,470,523		14,699,010
Equity securities, at fair value		550,485		338,899
Cash		880,099		646,556
Accrued investment income		116,196		114,641
Premiums receivable		1,618,186		1,299,150
Reinsurance recoverable on unpaid and paid losses and LAE		3,168,195		2,919,372
Ceded unearned premiums		1,168,258		975,469
Deferred acquisition costs		622,028		569,574
Receivable for securities sold		50,615		36,246
Goodwill and intangible assets		624,500		634,920	$ 566,662
Other assets		1,192,093		929,611
Total assets		35,572,603		32,218,329
Reserve for losses and loss adjustment expenses		12,389,384	$ 12,230,316	11,853,297	11,554,321	$ 11,424,337	$ 11,383,792
Unearned premiums		4,243,372		3,753,636
Reinsurance balances payable		601,891		393,107
Revolving credit agreement borrowings		490,720		455,682
Senior notes		1,871,386		1,733,528
Payable for securities purchased		176,130		90,034
Other liabilities		1,007,524		911,500
Total liabilities of consolidated VIE		23,510,794		21,780,650
Redeemable noncontrolling interests		48,789		206,292
Watford Holdings Ltd
Variable Interest Entity [Line Items]
Redeemable noncontrolling interests		48,789	$ 206,475	206,292	$ 206,199	$ 206,105	$ 205,922
Variable Interest Entity, Primary Beneficiary | Watford Holdings Ltd
Variable Interest Entity [Line Items]
Investments accounted for using the fair value option		2,048,295		2,312,003
Fixed maturities available for sale, at fair value		678,094		393,351
Equity securities, at fair value		43,488		32,206
Cash		80,390		63,529
Accrued investment income		18,277		19,461
Premiums receivable		302,265		227,301
Reinsurance recoverable on unpaid and paid losses and LAE		144,437		86,445
Ceded unearned premiums		129,909		61,587
Deferred acquisition costs		67,241		80,858
Receivable for securities sold		25,283		24,507
Goodwill and intangible assets		7,650		7,650
Other assets		66,165		63,959
Total assets		3,611,494		3,372,857
Reserve for losses and loss adjustment expenses		1,164,945		1,032,760
Unearned premiums		454,148		390,114
Reinsurance balances payable		79,264		21,034
Revolving credit agreement borrowings		490,720		455,682
Senior notes		172,350		0
Payable for securities purchased		40,586		60,142
Other liabilities	[1]	196,431		302,524
Total liabilities of consolidated VIE		2,598,444		2,262,256
Redeemable noncontrolling interests		$ 52,281		$ 220,992
[1]	Includes certain borrowings related to investing activities.

Variable Interest Entities an_5

Variable Interest Entities and Noncontrolling Interests - Non-redeemable noncontrolling interests (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interests, beginning of period			$ 791,560
Amounts attributable to noncontrolling interests	$ 136	$ 16,759	54,819	$ 36,251
Other comprehensive (income) loss attributable to noncontrolling interests	(764)	(1,158)	6,266	(2,908)
Non-redeemable noncontrolling interests, end of period	854,924	876,754	854,924	876,754
Watford Holdings Ltd
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interests, beginning of period	855,347	861,153	791,560	843,411
Additional paid in capital attributable to noncontrolling interests	205	0	2,279	0
Amounts attributable to noncontrolling interests	136	16,759	54,819	36,251
Other comprehensive (income) loss attributable to noncontrolling interests	(764)	(1,158)	6,266	(2,908)
Non-redeemable noncontrolling interests, end of period	$ 854,924	$ 876,754	$ 854,924	$ 876,754
Common shares | Watford Holdings Ltd
Noncontrolling Interest [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners	89.00%		89.00%

Variable Interest Entities an_6

Variable Interest Entities and Noncontrolling Interests - Redeemable noncontrolling interests (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 01, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jul. 31, 2019
Redeemable Noncontrolling Interest [Line Items]
Redeemable noncontrolling interests, beginning of period				$ 206,292
Redeemable noncontrolling interests, end of period		$ 48,789		48,789
Watford Holdings Ltd
Redeemable Noncontrolling Interest [Line Items]
Redeemable noncontrolling interests, beginning of period		206,475	$ 206,105	206,292	$ 205,922
Redemption of noncontrolling interests		(157,709)	0	(157,709)	0
Accretion of preference share issuance costs		23	94	206	277
Redeemable noncontrolling interests, end of period		$ 48,789	$ 206,199	$ 48,789	$ 206,199
Cumulative redeemable preference shares | Watford Holdings Ltd
Redeemable Noncontrolling Interest [Line Items]
Par value per share		$ 0.01		$ 0.01
Liquidation preference per share		25		25
Issue price per share		$ 24.50		$ 24.50
Variable Interest Entity, Primary Beneficiary | Watford Holdings Ltd
Redeemable Noncontrolling Interest [Line Items]
Preference shares, number of shares issued						9,065,200
Number of preference shares redeemed	6,919,998
Preferred shares, redemption price	$ 25.19748
Preference shares redeemed	$ 11,500
Redeemable noncontrolling interests, beginning of period				$ 220,992
Redeemable noncontrolling interests, end of period		$ 52,281		$ 52,281

Variable Interest Entities an_7

Variable Interest Entities and Noncontrolling Interests - Income or loss attributable to third party investors (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Noncontrolling Interest [Abstract]
Amounts attributable to non-redeemable noncontrolling interests	$ (136)	$ (16,759)	$ (54,819)	$ (36,251)
Dividends attributable to redeemable noncontrolling interests	(6,600)	(4,599)	(15,778)	(13,769)
Net (income) loss attributable to noncontrolling interests	$ (6,736)	$ (21,358)	$ (70,597)	$ (50,020)

Variable Interest Entities an_8

Variable Interest Entities and Noncontrolling Interests - Other variable interest entity disclosures (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	$ 1,765,018	$ 1,656,189
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Total VIE Assets	3,229,887	1,881,467
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability	(4,486)	1,752
Maximum Exposure to Loss - Off-Balance Sheet	50,140	11,190
Maximum Exposure to Loss	45,654	12,942
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2015-1 Ltd. (Jul-15)
Variable Interest Entity [Line Items]
Total VIE Assets	6,046	43,246
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability	0	112
Maximum Exposure to Loss - Off-Balance Sheet	2	498
Maximum Exposure to Loss	2	610
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2017-1 Ltd. (Oct-17)
Variable Interest Entity [Line Items]
Total VIE Assets	249,737	304,373
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability	(345)	165
Maximum Exposure to Loss - Off-Balance Sheet	3,526	1,312
Maximum Exposure to Loss	3,181	1,477
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2018-1 Ltd. (Apr-18)
Variable Interest Entity [Line Items]
Total VIE Assets	362,603	374,460
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability	(1,351)	132
Maximum Exposure to Loss - Off-Balance Sheet	7,035	3,539
Maximum Exposure to Loss	5,684	3,671
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2018-2 Ltd. (Aug-18)
Variable Interest Entity [Line Items]
Total VIE Assets	507,534	653,278
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability	(829)	874
Maximum Exposure to Loss - Off-Balance Sheet	3,395	4,005
Maximum Exposure to Loss	2,566	4,879
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2018-3 Ltd. (Oct-18)
Variable Interest Entity [Line Items]
Total VIE Assets	488,430	506,110
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability	(916)	469
Maximum Exposure to Loss - Off-Balance Sheet	4,600	1,836
Maximum Exposure to Loss	3,684	$ 2,305
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2019-1 Ltd. (Mar-19)
Variable Interest Entity [Line Items]
Total VIE Assets	293,595
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability	(210)
Maximum Exposure to Loss - Off-Balance Sheet	4,533
Maximum Exposure to Loss	4,323
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2019-2 Ltd. (Apr-19)
Variable Interest Entity [Line Items]
Total VIE Assets	621,022
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability	(367)
Maximum Exposure to Loss - Off-Balance Sheet	15,161
Maximum Exposure to Loss	14,794
Variable Interest Entity, Not Primary Beneficiary | Bellemeade 2019-3 Ltd. (July-19)
Variable Interest Entity [Line Items]
Total VIE Assets	700,920
Maximum Exposure to Loss - On-Balance Sheet (Asset) Liability	(468)
Maximum Exposure to Loss - Off-Balance Sheet	11,888
Maximum Exposure to Loss	$ 11,420

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) - Amounts reclassified from accumulated other comprehensive income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other-than-temporary impairment losses	$ (1,163)	$ (492)	$ (2,521)	$ (1,124)
Income before income taxes	437,305	282,122	1,509,006	750,436
Income tax expense	(38,116)	(33,356)	(128,474)	(78,939)
Net of tax	392,453	227,408	1,309,935	621,477
Reclassification out of accumulated other comprehensive income | Unrealized appreciation on available-for-sale investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses)	43,124	(23,888)	114,642	(130,409)
Other-than-temporary impairment losses	(1,163)	(492)	(2,521)	(1,124)
Income before income taxes	41,961	(24,380)	112,121	(131,533)
Income tax expense	(3,218)	1,177	(7,812)	9,226
Net of tax	$ 38,743	$ (23,203)	$ 104,309	$ (122,307)

Other Comprehensive Income (L_4

Other Comprehensive Income (Loss) - Components of other comprehensive income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Before tax amount:
Unrealized holding gains (losses) arising during period, before tax	$ 70,449	$ (57,812)	$ 573,513	$ (335,789)
Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss), before tax	0	0	0	0
Less reclassification of net realized gains included in net income, before tax	41,961	(24,380)	112,121	(131,533)
Foreign currency translation adjustments, before tax	(16,507)	2,167	(6,454)	(9,102)
Other comprehensive income (loss), before tax	11,981	(31,265)	454,938	(213,358)
Tax expense (benefit):
Unrealized holding gains (losses) arising during period, tax	11,159	(4,504)	65,863	(30,533)
Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss), tax	0	0	0	0
Less reclassification of net realized gains included in net income, tax	3,218	(1,177)	7,812	(9,226)
Foreign currency translation adjustments, tax	(83)	104	187	148
Other comprehensive income (loss), tax	7,858	(3,223)	58,238	(21,159)
Net of tax amount:
Unrealized holding gains (losses) arising during period, net of tax	59,290	(53,308)	507,650	(305,256)
Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss), net of tax	0	0	0	0
Less reclassification of net realized gains included in net income, net of tax	38,743	(23,203)	104,309	(122,307)
Foreign currency translation adjustments, net of tax	(16,424)	2,063	(6,641)	(9,250)
Net current period other comprehensive income (loss)	$ 4,123	$ (28,042)	$ 396,700	$ (192,199)

Guarantor Financial Informati_3

Guarantor Financial Information - Condensed consolidating balance sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Assets
Total investments	$ 23,617,335		$ 21,745,284
Cash	880,099		646,556
Investments in subsidiaries	0		0
Due from subsidiaries and affiliates	0		0
Premiums receivable	1,618,186		1,299,150
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	3,168,195		2,919,372
Contractholder receivables	2,094,683		2,079,111
Ceded unearned premiums	1,168,258		975,469
Deferred acquisition costs	622,028		569,574
Goodwill and intangible assets	624,500		634,920	$ 566,662
Other assets	1,779,319		1,348,893
Total assets	35,572,603		32,218,329
Liabilities
Reserve for losses and loss adjustment expenses	12,389,384	$ 12,230,316	11,853,297	11,554,321	$ 11,424,337	$ 11,383,792
Unearned premiums	4,243,372		3,753,636
Reinsurance balances payable	601,891		393,107
Contractholder payables	2,094,683		2,079,111
Collateral held for insured obligations	205,449		236,630
Senior notes	1,871,386		1,733,528
Revolving credit agreement borrowings	490,720		455,682
Due to subsidiaries and affiliates	0		0
Other liabilities	1,613,909		1,275,659
Total liabilities	23,510,794		21,780,650
Redeemable noncontrolling interests	48,789		206,292
Shareholders' Equity
Total shareholders’ equity available to Arch	11,158,096		9,439,827	9,355,148
Non-redeemable noncontrolling interests	854,924		791,560	876,754
Total shareholders’ equity	12,013,020		10,231,387	$ 10,231,902
Total liabilities, noncontrolling interests and shareholders’ equity	35,572,603		32,218,329
Reportable Legal Entities | Arch Capital (Parent Guarantor)
Assets
Total investments	41		104
Cash	12,696		6,125
Investments in subsidiaries	11,454,186		9,735,256
Due from subsidiaries and affiliates	106		9
Premiums receivable	0		0
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	0		0
Contractholder receivables	0		0
Ceded unearned premiums	0		0
Deferred acquisition costs	0		0
Goodwill and intangible assets	0		0
Other assets	21,336		12,588
Total assets	11,488,365		9,754,082
Liabilities
Reserve for losses and loss adjustment expenses	0		0
Unearned premiums	0		0
Reinsurance balances payable	0		0
Contractholder payables	0		0
Collateral held for insured obligations	0		0
Senior notes	297,228		297,150
Revolving credit agreement borrowings	0		0
Due to subsidiaries and affiliates	8		0
Other liabilities	33,033		17,105
Total liabilities	330,269		314,255
Redeemable noncontrolling interests	0		0
Shareholders' Equity
Total shareholders’ equity available to Arch	11,158,096		9,439,827
Non-redeemable noncontrolling interests	0		0
Total shareholders’ equity	11,158,096		9,439,827
Total liabilities, noncontrolling interests and shareholders’ equity	11,488,365		9,754,082
Reportable Legal Entities | Arch-U.S. (Subsidiary Issuer)
Assets
Total investments	918,720		452,674
Cash	72,727		5,940
Investments in subsidiaries	4,189,656		3,999,243
Due from subsidiaries and affiliates	2		2
Premiums receivable	0		0
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	0		0
Contractholder receivables	0		0
Ceded unearned premiums	0		0
Deferred acquisition costs	0		0
Goodwill and intangible assets	0		0
Other assets	25,586		80,949
Total assets	5,206,691		4,538,808
Liabilities
Reserve for losses and loss adjustment expenses	0		0
Unearned premiums	0		0
Reinsurance balances payable	0		0
Contractholder payables	0		0
Collateral held for insured obligations	0		0
Senior notes	494,803		494,723
Revolving credit agreement borrowings	0		0
Due to subsidiaries and affiliates	542,103		536,805
Other liabilities	55,585		26,270
Total liabilities	1,092,491		1,057,798
Redeemable noncontrolling interests	0		0
Shareholders' Equity
Total shareholders’ equity available to Arch	4,114,200		3,481,010
Non-redeemable noncontrolling interests	0		0
Total shareholders’ equity	4,114,200		3,481,010
Total liabilities, noncontrolling interests and shareholders’ equity	$ 5,206,691		4,538,808
Percentage Ownership of Subsidiary	100.00%
Reportable Legal Entities | Other Arch Capital Subsidiaries
Assets
Total investments	$ 22,737,556		21,307,206
Cash	794,676		634,491
Investments in subsidiaries	0		0
Due from subsidiaries and affiliates	1,899,559		1,802,686
Premiums receivable	2,446,539		1,834,389
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	8,490,131		8,618,660
Contractholder receivables	2,094,683		2,079,111
Ceded unearned premiums	2,149,492		1,730,262
Deferred acquisition costs	674,559		618,535
Goodwill and intangible assets	624,500		634,920
Other assets	1,875,817		1,466,438
Total assets	43,787,512		40,726,698
Liabilities
Reserve for losses and loss adjustment expenses	17,486,844		17,345,142
Unearned premiums	5,224,606		4,508,429
Reinsurance balances payable	1,430,244		928,346
Contractholder payables	2,094,683		2,079,111
Collateral held for insured obligations	205,449		236,630
Senior notes	1,114,355		941,655
Revolving credit agreement borrowings	490,720		455,682
Due to subsidiaries and affiliates	1,357,556		1,265,892
Other liabilities	1,946,208		1,699,768
Total liabilities	31,350,665		29,460,655
Redeemable noncontrolling interests	52,281		220,992
Shareholders' Equity
Total shareholders’ equity available to Arch	11,529,642		10,253,491
Non-redeemable noncontrolling interests	854,924		791,560
Total shareholders’ equity	12,384,566		11,045,051
Total liabilities, noncontrolling interests and shareholders’ equity	43,787,512		40,726,698
Consolidating Adjustments and Eliminations
Assets
Total investments	(38,982)		(14,700)
Cash	0		0
Investments in subsidiaries	(15,643,842)		(13,734,499)
Due from subsidiaries and affiliates	(1,899,667)		(1,802,697)
Premiums receivable	(828,353)		(535,239)
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	(5,321,936)		(5,699,288)
Contractholder receivables	0		0
Ceded unearned premiums	(981,234)		(754,793)
Deferred acquisition costs	(52,531)		(48,961)
Goodwill and intangible assets	0		0
Other assets	(143,420)		(211,082)
Total assets	(24,909,965)		(22,801,259)
Liabilities
Reserve for losses and loss adjustment expenses	(5,097,460)		(5,491,845)
Unearned premiums	(981,234)		(754,793)
Reinsurance balances payable	(828,353)		(535,239)
Contractholder payables	0		0
Collateral held for insured obligations			0
Senior notes	(35,000)		0
Revolving credit agreement borrowings	0		0
Due to subsidiaries and affiliates	(1,899,667)		(1,802,697)
Other liabilities	(420,917)		(467,484)
Total liabilities	(9,262,631)		(9,052,058)
Redeemable noncontrolling interests	(3,492)		(14,700)
Shareholders' Equity
Total shareholders’ equity available to Arch	(15,643,842)		(13,734,501)
Non-redeemable noncontrolling interests	0		0
Total shareholders’ equity	(15,643,842)		(13,734,501)
Total liabilities, noncontrolling interests and shareholders’ equity	$ (24,909,965)		$ (22,801,259)

Guarantor Financial Informati_4

Guarantor Financial Information - Condensed consolidating statement of income and comprehensive income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues
Net premiums earned	$ 1,438,023	$ 1,290,878	$ 4,270,616	$ 3,862,540
Net investment income	161,488	144,024	473,475	406,416
Net realized gains (losses)	62,518	(51,705)	324,889	(239,314)
Net impairment losses recognized in earnings	(1,163)	(492)	(2,521)	(1,124)
Other underwriting income	3,326	5,823	18,104	15,046
Equity in net income of investment funds accounted for using the equity method	17,130	15,982	96,533	52,523
Other income (loss)	1,338	(726)	3,550	2,461
Total revenues	1,682,660	1,403,784	5,184,646	4,098,548
Expenses
Losses and loss adjustment expenses	802,455	699,420	2,288,530	2,062,433
Acquisition expenses	211,120	201,602	619,057	595,816
Other operating expenses	196,512	161,098	596,589	512,294
Corporate expenses	17,061	14,335	53,274	52,159
Amortization of intangible assets	20,003	26,315	60,214	79,523
Interest expense	31,328	29,730	89,673	90,710
Net foreign exchange (gains) losses	(33,124)	(10,838)	(31,697)	(44,823)
Total expenses	1,245,355	1,121,662	3,675,640	3,348,112
Income (loss) before income taxes	437,305	282,122	1,509,006	750,436
Income tax (expense) benefit	(38,116)	(33,356)	(128,474)	(78,939)
Income (loss) before equity in net income of subsidiaries	399,189	248,766	1,380,532	671,497
Equity in net income of subsidiaries	0	0	0	0
Net income	399,189	248,766	1,380,532	671,497
Net (income) loss attributable to noncontrolling interests	(6,736)	(21,358)	(70,597)	(50,020)
Net income available to Arch	392,453	227,408	1,309,935	621,477
Preferred dividends	(10,403)	(10,402)	(31,209)	(31,242)
Loss on redemption of preferred shares	0	0	0	(2,710)
Net income available to Arch common shareholders	382,050	217,006	1,278,726	587,525
Comprehensive income available to Arch	397,340	200,524	1,700,369	432,186
Reportable Legal Entities | Arch Capital (Parent Guarantor)
Revenues
Net premiums earned	0	0	0	0
Net investment income	81	2	165	37
Net realized gains (losses)	0	0	0	29
Net impairment losses recognized in earnings	0	0	0	0
Other underwriting income	0	0	0	0
Equity in net income of investment funds accounted for using the equity method	0	0	0	0
Other income (loss)	(153)	(195)	(634)	2,066
Total revenues	(72)	(193)	(469)	2,132
Expenses
Losses and loss adjustment expenses	0	0	0	0
Acquisition expenses	0	0	0	0
Other operating expenses	0	0	0	0
Corporate expenses	15,066	15,170	46,666	47,981
Amortization of intangible assets	0	0	0	0
Interest expense	5,539	5,536	16,615	16,609
Net foreign exchange (gains) losses	1	0	3	29
Total expenses	20,606	20,706	63,284	64,619
Income (loss) before income taxes	(20,678)	(20,899)	(63,753)	(62,487)
Income tax (expense) benefit	0	0	0	0
Income (loss) before equity in net income of subsidiaries	(20,678)	(20,899)	(63,753)	(62,487)
Equity in net income of subsidiaries	413,131	248,307	1,373,688	683,964
Net income	392,453	227,408	1,309,935	621,477
Net (income) loss attributable to noncontrolling interests	0	0	0	0
Net income available to Arch	392,453	227,408	1,309,935	621,477
Preferred dividends	(10,403)	(10,402)	(31,209)	(31,242)
Loss on redemption of preferred shares				(2,710)
Net income available to Arch common shareholders	382,050	217,006	1,278,726	587,525
Comprehensive income available to Arch	397,340	200,524	1,700,369	432,186
Reportable Legal Entities | Arch-U.S. (Subsidiary Issuer)
Revenues
Net premiums earned	0	0	0	0
Net investment income	2,899	1,202	9,425	2,020
Net realized gains (losses)	1,880	(64)	16,223	(71)
Net impairment losses recognized in earnings	0	0	0	0
Other underwriting income	0	0	0	0
Equity in net income of investment funds accounted for using the equity method	600	0	536	0
Other income (loss)	0	0	0	0
Total revenues	5,379	1,138	26,184	1,949
Expenses
Losses and loss adjustment expenses	0	0	0	0
Acquisition expenses	0	0	0	0
Other operating expenses	0	0	0	0
Corporate expenses	1,631	446	5,912	1,205
Amortization of intangible assets	0	0	0	0
Interest expense	12,019	12,075	35,966	36,014
Net foreign exchange (gains) losses	0	0	0	0
Total expenses	13,650	12,521	41,878	37,219
Income (loss) before income taxes	(8,271)	(11,383)	(15,694)	(35,270)
Income tax (expense) benefit	1,647	2,276	3,491	7,704
Income (loss) before equity in net income of subsidiaries	(6,624)	(9,107)	(12,203)	(27,566)
Equity in net income of subsidiaries	124,814	92,906	410,115	266,053
Net income	118,190	83,799	397,912	238,487
Net (income) loss attributable to noncontrolling interests	0	0	0	0
Net income available to Arch	118,190	83,799	397,912	238,487
Preferred dividends	0	0	0	0
Loss on redemption of preferred shares				0
Net income available to Arch common shareholders	118,190	83,799	397,912	238,487
Comprehensive income available to Arch	138,832	77,389	608,108	153,992
Reportable Legal Entities | Other Arch Capital Subsidiaries
Revenues
Net premiums earned	1,438,023	1,290,878	4,270,616	3,862,540
Net investment income	181,621	165,289	532,031	471,588
Net realized gains (losses)	66,683	(51,641)	320,356	(239,272)
Net impairment losses recognized in earnings	(1,163)	(492)	(2,521)	(1,124)
Other underwriting income	3,326	5,823	18,104	15,046
Equity in net income of investment funds accounted for using the equity method	16,530	15,982	95,997	52,523
Other income (loss)	1,491	(531)	4,184	395
Total revenues	1,706,511	1,425,308	5,238,767	4,161,696
Expenses
Losses and loss adjustment expenses	802,455	699,420	2,288,530	2,062,433
Acquisition expenses	211,120	201,602	619,057	595,816
Other operating expenses	196,512	161,098	596,589	512,294
Corporate expenses	364	(1,281)	696	2,973
Amortization of intangible assets	20,003	26,315	60,214	79,523
Interest expense	36,712	34,276	104,430	104,359
Net foreign exchange (gains) losses	(25,405)	(10,426)	(26,715)	(37,347)
Total expenses	1,241,761	1,111,004	3,642,801	3,320,051
Income (loss) before income taxes	464,750	314,304	1,595,966	841,645
Income tax (expense) benefit	(39,763)	(35,632)	(131,965)	(86,643)
Income (loss) before equity in net income of subsidiaries	424,987	278,672	1,464,001	755,002
Equity in net income of subsidiaries	0	0	0	0
Net income	424,987	278,672	1,464,001	755,002
Net (income) loss attributable to noncontrolling interests	(6,906)	(21,669)	(71,405)	(50,976)
Net income available to Arch	418,081	257,003	1,392,596	704,026
Preferred dividends	0	0	0	0
Loss on redemption of preferred shares				0
Net income available to Arch common shareholders	418,081	257,003	1,392,596	704,026
Comprehensive income available to Arch	427,238	230,565	1,779,463	522,448
Consolidating Adjustments and Eliminations
Revenues
Net premiums earned	0	0	0	0
Net investment income	(23,113)	(22,469)	(68,146)	(67,229)
Net realized gains (losses)	(6,045)	0	(11,690)	0
Net impairment losses recognized in earnings	0	0	0	0
Other underwriting income	0	0	0	0
Equity in net income of investment funds accounted for using the equity method	0	0	0	0
Other income (loss)	0	0	0	0
Total revenues	(29,158)	(22,469)	(79,836)	(67,229)
Expenses
Losses and loss adjustment expenses	0	0	0	0
Acquisition expenses	0	0	0	0
Other operating expenses	0	0	0	0
Corporate expenses	0	0	0	0
Amortization of intangible assets	0	0	0	0
Interest expense	(22,942)	(22,157)	(67,338)	(66,272)
Net foreign exchange (gains) losses	(7,720)	(412)	(4,985)	(7,505)
Total expenses	(30,662)	(22,569)	(72,323)	(73,777)
Income (loss) before income taxes	1,504	100	(7,513)	6,548
Income tax (expense) benefit	0	0	0	0
Income (loss) before equity in net income of subsidiaries	1,504	100	(7,513)	6,548
Equity in net income of subsidiaries	(537,945)	(341,213)	(1,783,803)	(950,017)
Net income	(536,441)	(341,113)	(1,791,316)	(943,469)
Net (income) loss attributable to noncontrolling interests	170	311	808	956
Net income available to Arch	(536,271)	(340,802)	(1,790,508)	(942,513)
Preferred dividends	0	0	0	0
Loss on redemption of preferred shares				0
Net income available to Arch common shareholders	(536,271)	(340,802)	(1,790,508)	(942,513)
Comprehensive income available to Arch	$ (566,070)	$ (307,954)	$ (2,387,571)	$ (676,440)

Guarantor Financial Informati_5

Guarantor Financial Information - Condensed consolidating statement of cash flows (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018
Operating Activities
Net Cash Provided by (Used in) Operating Activities		$ 1,543,139	$ 1,120,987
Investing Activities
Purchases of fixed maturity investments		(24,010,623)	(24,837,917)
Purchases of equity securities		(524,051)	(819,342)
Purchases of other investments		(1,014,925)	(1,543,332)
Proceeds from sales of fixed maturity investments		22,707,854	23,310,203
Proceeds from sales of equity securities		371,130	866,919
Proceeds from sales, redemptions and maturities of other investments		827,517	1,178,035
Proceeds from redemptions and maturities of fixed maturity investments		394,719	724,021
Net settlements of derivative instruments		92,423	765
Net (purchases) sales of short-term investments		129,078	554,315
Change in cash collateral related to securities lending		6,990	137,073
Contributions to subsidiaries		0	0
Issuance of intercompany loans		0
Purchases of fixed assets		(27,635)	(19,050)
Other		(202,953)	58,227
Net Cash Provided By (Used For) Investing Activities		(1,250,476)	(390,083)
Financing Activities
Redemption of preferred shares		0	(92,555)
Purchases of common shares under share repurchase program		(2,871)	(184,529)
Proceeds from common shares issued, net		518	(12,029)
Proceeds from intercompany borrowings		0
Proceeds from borrowings		200,083	167,259
Repayments of intercompany borrowings		0
Repayments of borrowings		(27,538)	(427,000)
Change in cash collateral related to securities lending		(6,990)	(137,073)
Change in third party investment in redeemable noncontrolling interests		(161,874)	0
Dividends paid to redeemable noncontrolling interests		(11,408)	(13,491)
Dividends paid to parent	[1]	0	0
Other		(5,207)	(6,084)
Preferred dividends paid		(31,209)	(31,242)
Net Cash Provided By (Used For) Financing Activities		(46,496)	(736,744)
Effects of exchange rate changes on foreign currency cash and restricted cash		(8,335)	(11,625)
Increase (decrease) in cash and restricted cash		237,832	(17,465)
Cash and restricted cash, beginning of year		724,643	727,284
Cash and restricted cash, end of period		962,475	709,819
Reportable Legal Entities | Arch Capital (Parent Guarantor)
Operating Activities
Net Cash Provided by (Used in) Operating Activities		42,221	222,097
Investing Activities
Purchases of fixed maturity investments		0	0
Purchases of equity securities		0	0
Purchases of other investments		0	0
Proceeds from sales of fixed maturity investments		0	0
Proceeds from sales of equity securities		0	0
Proceeds from sales, redemptions and maturities of other investments		0	0
Proceeds from redemptions and maturities of fixed maturity investments		0	0
Net settlements of derivative instruments		0	0
Net (purchases) sales of short-term investments		63	96,397
Change in cash collateral related to securities lending		0	0
Contributions to subsidiaries		(2,121)	0
Issuance of intercompany loans		0
Purchases of fixed assets		(32)	(71)
Other		0	(4)
Net Cash Provided By (Used For) Investing Activities		(2,090)	96,322
Financing Activities
Redemption of preferred shares			(92,555)
Purchases of common shares under share repurchase program		(2,871)	(184,529)
Proceeds from common shares issued, net		518	(12,029)
Proceeds from intercompany borrowings		0
Proceeds from borrowings		0	0
Repayments of intercompany borrowings		0
Repayments of borrowings		0	0
Change in cash collateral related to securities lending		0	0
Change in third party investment in redeemable noncontrolling interests		0
Dividends paid to redeemable noncontrolling interests		0	0
Dividends paid to parent	[1]	0	0
Other		0	0
Preferred dividends paid		(31,209)	(31,242)
Net Cash Provided By (Used For) Financing Activities		(33,562)	(320,355)
Effects of exchange rate changes on foreign currency cash and restricted cash		0	0
Increase (decrease) in cash and restricted cash		6,569	(1,936)
Cash and restricted cash, beginning of year		6,159	10,048
Cash and restricted cash, end of period		12,728	8,112
Reportable Legal Entities | Arch-U.S. (Subsidiary Issuer)
Operating Activities
Net Cash Provided by (Used in) Operating Activities		525,712	176,851
Investing Activities
Purchases of fixed maturity investments		(868,773)	(214,449)
Purchases of equity securities		(74,502)	0
Purchases of other investments		(28,557)	0
Proceeds from sales of fixed maturity investments		482,804	111,533
Proceeds from sales of equity securities		7,441	0
Proceeds from sales, redemptions and maturities of other investments		1,057	0
Proceeds from redemptions and maturities of fixed maturity investments		0	0
Net settlements of derivative instruments		0	0
Net (purchases) sales of short-term investments		31,605	(49,031)
Change in cash collateral related to securities lending		0	0
Contributions to subsidiaries		0	(2,500)
Issuance of intercompany loans		0
Purchases of fixed assets		0	0
Other		(10,000)	0
Net Cash Provided By (Used For) Investing Activities		(458,925)	(154,447)
Financing Activities
Redemption of preferred shares			0
Purchases of common shares under share repurchase program		0	0
Proceeds from common shares issued, net		0	0
Proceeds from intercompany borrowings		0
Proceeds from borrowings		0	0
Repayments of intercompany borrowings		0
Repayments of borrowings		0	0
Change in cash collateral related to securities lending		0	0
Change in third party investment in redeemable noncontrolling interests		0
Dividends paid to redeemable noncontrolling interests		0	0
Dividends paid to parent	[1]	0	0
Other		0	0
Preferred dividends paid		0	0
Net Cash Provided By (Used For) Financing Activities		0	0
Effects of exchange rate changes on foreign currency cash and restricted cash		0	0
Increase (decrease) in cash and restricted cash		66,787	22,404
Cash and restricted cash, beginning of year		5,940	30,380
Cash and restricted cash, end of period		72,727	52,784
Reportable Legal Entities | Other Arch Capital Subsidiaries
Operating Activities
Net Cash Provided by (Used in) Operating Activities		1,554,406	1,622,248
Investing Activities
Purchases of fixed maturity investments		(23,313,996)	(25,229,184)
Purchases of equity securities		(520,292)	(819,342)
Purchases of other investments		(986,368)	(1,543,332)
Proceeds from sales of fixed maturity investments		22,373,404	23,804,386
Proceeds from sales of equity securities		434,432	866,919
Proceeds from sales, redemptions and maturities of other investments		826,460	1,178,035
Proceeds from redemptions and maturities of fixed maturity investments		394,719	724,021
Net settlements of derivative instruments		92,423	765
Net (purchases) sales of short-term investments		97,410	506,949
Change in cash collateral related to securities lending		6,990	137,073
Contributions to subsidiaries		(70,125)	(29,646)
Issuance of intercompany loans		(53,828)
Purchases of fixed assets		(27,603)	(18,979)
Other		(192,953)	58,231
Net Cash Provided By (Used For) Investing Activities		(939,327)	(364,104)
Financing Activities
Redemption of preferred shares			0
Purchases of common shares under share repurchase program		0	0
Proceeds from common shares issued, net		72,246	32,146
Proceeds from intercompany borrowings		53,828
Proceeds from borrowings		235,083	167,259
Repayments of intercompany borrowings		0
Repayments of borrowings		(27,538)	(427,000)
Change in cash collateral related to securities lending		(6,990)	(137,073)
Change in third party investment in redeemable noncontrolling interests		(173,082)
Dividends paid to redeemable noncontrolling interests		(12,217)	(14,447)
Dividends paid to parent	[1]	(578,391)	(899,253)
Other		(5,207)	(6,084)
Preferred dividends paid		0	0
Net Cash Provided By (Used For) Financing Activities		(442,268)	(1,284,452)
Effects of exchange rate changes on foreign currency cash and restricted cash		(8,335)	(11,625)
Increase (decrease) in cash and restricted cash		164,476	(37,933)
Cash and restricted cash, beginning of year		712,544	686,856
Cash and restricted cash, end of period		877,020	648,923
Consolidating Adjustments and Eliminations
Operating Activities
Net Cash Provided by (Used in) Operating Activities		(579,200)	(900,209)
Investing Activities
Purchases of fixed maturity investments		172,146	605,716
Purchases of equity securities		70,743	0
Purchases of other investments		0	0
Proceeds from sales of fixed maturity investments		(148,354)	(605,716)
Proceeds from sales of equity securities		(70,743)	0
Proceeds from sales, redemptions and maturities of other investments		0	0
Proceeds from redemptions and maturities of fixed maturity investments		0	0
Net settlements of derivative instruments		0	0
Net (purchases) sales of short-term investments		0	0
Change in cash collateral related to securities lending		0	0
Contributions to subsidiaries		72,246	32,146
Issuance of intercompany loans		53,828
Purchases of fixed assets		0	0
Other		0	0
Net Cash Provided By (Used For) Investing Activities		149,866	32,146
Financing Activities
Redemption of preferred shares			0
Purchases of common shares under share repurchase program		0	0
Proceeds from common shares issued, net		(72,246)	(32,146)
Proceeds from intercompany borrowings		(53,828)
Proceeds from borrowings		(35,000)	0
Repayments of intercompany borrowings		0
Repayments of borrowings		0	0
Change in cash collateral related to securities lending		0	0
Change in third party investment in redeemable noncontrolling interests		11,208
Dividends paid to redeemable noncontrolling interests		809	956
Dividends paid to parent	[1]	578,391	899,253
Other		0	0
Preferred dividends paid		0	0
Net Cash Provided By (Used For) Financing Activities		429,334	868,063
Effects of exchange rate changes on foreign currency cash and restricted cash		0	0
Increase (decrease) in cash and restricted cash		0	0
Cash and restricted cash, beginning of year		0	0
Cash and restricted cash, end of period		$ 0	$ 0
[1]	Dividends received by parent are included in net cash provided by (used for) operating activities

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Effective tax rate on income before income taxes (percentage)	8.50%	10.50%
Statutory federal tax rate	21.00%
Tax benefit on share-based compensation	0.40%
Net deferred tax liabilities	$ 55.9
Net deferred tax assets			$ 22.5
Income taxes paid (recovered)	$ 47.1	$ (34)

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ in Millions	1 Months Ended
	Oct. 31, 2019	Nov. 08, 2019	Sep. 30, 2019
Subsequent Event | Variable Interest Entity, Not Primary Beneficiary | Bellemeade Re 2019-4 Ltd.
Bellemeade 2019-3 Ltd.
Aggregate excess of loss reinsurance agreement	$ 577.3
Aggregate losses	$ 162.4
Agreement period	10 years
SPV issuance of insurance-linked notes	$ 577.3
Common shares
Bellemeade 2019-3 Ltd.
Remaining authorized repurchase amount			$ 160.9
Common shares | Subsequent Event
Bellemeade 2019-3 Ltd.
Authorized repurchase amount		$ 1,000