Arch Capital (ACGL) 10-Q 5 Aug 16 2016 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2016	Jul. 28, 2016
Document and Entity Information [Abstract]
Entity Registrant Name	ARCH CAPITAL GROUP LTD.
Entity Central Index Key	947,484
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		122,572,026

Unaudited Consolidated Balance

Unaudited Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Investments:
Fixed maturities available for sale, at fair value (amortized cost: $10,879,863 and $10,515,440)	$ 11,050,464	$ 10,459,353
Short-term investments available for sale, at fair value (amortized cost: $855,764 and $591,141)	853,531	587,904
Collateral received under securities lending, at fair value (amortized cost: $338,318 and $385,984)	338,326	389,336
Equity securities available for sale, at fair value (cost: $414,537 and $543,767)	490,815	618,405
Other investments available for sale, at fair value (cost: $167,914 and $261,343)	182,957	300,476
Investments accounted for using the fair value option	3,066,029	2,894,494
Investments accounted for using the equity method	685,766	592,973
Total investments	16,667,888	15,842,941
Cash	516,591	553,326
Accrued investment income	85,317	87,206
Securities pledged under securities lending, at fair value (amortized cost: $328,274 and $386,411)	330,773	384,081
Premiums receivable	1,260,607	983,443
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	2,034,970	1,867,373
Contractholder receivables	1,600,426	1,486,296
Prepaid reinsurance premiums	540,954	427,609
Deferred acquisition costs, net	462,906	433,477
Receivable for securities sold	142,315	45,505
Goodwill and intangible assets	88,327	97,531
Other assets	680,843	968,482
Total assets	24,411,917	23,177,270
Liabilities
Reserve for losses and loss adjustment expenses	9,471,647	9,125,250
Unearned premiums	2,618,359	2,333,932
Reinsurance balances payable	295,987	224,120
Contractholder payables	1,600,426	1,486,296
Collateral held for insured obligations	261,228	248,982
Deposit accounting liabilities	22,325	260,364
Senior notes	791,392	791,306
Revolving credit agreement borrowings	397,830	530,434
Securities lending payable	338,318	393,844
Payable for securities purchased	382,834	64,996
Other liabilities	533,694	568,852
Total liabilities	16,714,040	16,028,376
Commitments and Contingencies
Redeemable noncontrolling interests	205,366	205,182
Shareholders' Equity
Non-cumulative preferred shares	325,000	325,000
Common shares ($0.0033 par, shares issued: 174,355,513 and 173,107,849)	581	577
Additional paid-in capital	517,942	467,339
Retained earnings	7,725,255	7,370,371
Accumulated other comprehensive income (loss), net of deferred income tax	163,834	(16,502)
Common shares held in treasury, at cost (shares: 51,783,253 and 50,480,066)	(2,028,690)	(1,941,904)
Total shareholders' equity available to Arch	6,703,922	6,204,881
Non-redeemable noncontrolling interests	788,589	738,831
Total shareholders' equity	7,492,511	6,943,712
Total liabilities, noncontrolling interests and shareholders' equity	$ 24,411,917	$ 23,177,270

Unaudited Consolidated Balance3

Unaudited Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fixed maturities available for sale, at amortized cost	$ 10,879,863	$ 10,515,440
Short-term investments available for sale, at amortized cost	855,764	591,141
Collateral received under securities lending, at amortized cost	338,318	385,984
Equity securities available for sale, at cost	414,537	543,767
Other investments available for sale, at cost	167,914	261,343
Securities pledged under securities lending, at amortized cost	$ 328,274	$ 386,411
Common shares, par value per share	$ 0.0033	$ 0.0033
Common shares issued (shares)	174,355,513	173,107,849
Common shares held in treasury (shares)	51,783,253	50,480,066

Unaudited Consolidated Statemen

Unaudited Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues
Net premiums written	$ 1,023,563	$ 943,580	$ 2,144,798	$ 2,010,575
Change in unearned premiums	(17,578)	(142)	(187,234)	(156,873)
Net premiums earned	1,005,985	943,438	1,957,564	1,853,702
Net investment income	88,338	86,963	182,073	165,957
Net realized gains (losses)	68,218	(35,725)	105,542	47,623
Other-than-temporary impairment losses	(5,395)	(1,126)	(13,132)	(8,373)
Less investment impairments recognized in other comprehensive income, before taxes	52	13	150	1,461
Net impairment losses recognized in earnings	(5,343)	(1,113)	(12,982)	(6,912)
Other underwriting income	25,224	7,717	30,271	19,253
Equity in net income (loss) of investment funds accounted for using the equity method	8,737	16,167	15,392	22,056
Other income (loss)	(7)	2,205	(32)	317
Total revenues	1,191,152	1,019,652	2,277,828	2,101,996
Expenses
Losses and loss adjustment expenses	584,592	519,426	1,107,541	1,013,142
Acquisition expenses	175,281	175,425	345,746	338,501
Other operating expenses	159,590	151,190	311,859	299,727
Corporate expenses	17,200	17,418	26,583	26,763
Interest expense	15,663	4,011	31,770	16,747
Net foreign exchange (gains) losses	(24,662)	19,583	(1,096)	(46,918)
Total expenses	927,664	887,053	1,822,403	1,647,962
Income before income taxes	263,488	132,599	455,425	454,034
Income tax expense	(14,131)	(6,780)	(30,441)	(19,458)
Net income	249,357	125,819	424,984	434,576
Net (income) loss attributable to noncontrolling interests	(38,302)	(10,029)	(59,131)	(35,450)
Net income available to Arch	211,055	115,790	365,853	399,126
Preferred dividends	(5,485)	(5,485)	(10,969)	(10,969)
Net income available to Arch common shareholders	$ 205,570	$ 110,305	$ 354,884	$ 388,157
Net income per common share
Basic (per share)	$ 1.70	$ 0.91	$ 2.94	$ 3.16
Diluted (per share)	$ 1.65	$ 0.88	$ 2.85	$ 3.05
Weighted average common shares and common share equivalents outstanding
Basic (shares)	120,599,060	121,719,214	120,513,620	122,957,384
Diluted (shares)	124,365,596	125,885,420	124,425,126	127,156,713

Unaudited Consolidated Stateme5

Unaudited Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Comprehensive Income
Net income	$ 249,357	$ 125,819	$ 424,984	$ 434,576
Unrealized appreciation (decline) in value of available-for-sale investments:
Unrealized holding gains (losses) arising during period	102,460	(81,935)	235,441	2,369
Portion of other-than-temporary impairment losses recognized in other comprehensive income, net of deferred income tax	(52)	(13)	(150)	(1,461)
Reclassification of net realized (gains) losses, net of income taxes, included in net income	(22,094)	(21,214)	(54,317)	(52,146)
Foreign currency translation adjustments	(18,151)	11,580	(838)	(11,177)
Comprehensive income	311,520	34,237	605,120	372,161
Net (income) loss attributable to noncontrolling interests	(38,302)	(10,029)	(59,131)	(35,450)
Foreign currency translation adjustments attributable to noncontrolling interests	42	0	200	0
Comprehensive income available to Arch	$ 273,260	$ 24,208	$ 546,189	$ 336,711

Unaudited Consolidated Stateme6

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
Balance at beginning of year at Dec. 31, 2014		$ 325,000	$ 572	$ 383,073	$ 6,854,571	$ 128,856	$ 161,598	$ (32,742)	$ (1,562,019)
Common shares issued, net			4	7,378
Exercise of stock options				9,624
Amortization of share-based compensation				36,044
Other				1,414
Net income	$ 434,576				434,576
Net (income) loss attributable to noncontrolling interests	(35,450)				(35,450)
Preferred share dividends	(10,969)				(10,969)
Unrealized holding gains (losses) arising during period, net of reclassification adjustment							(49,777)
Portion of other-than-temporary impairment losses recognized in other comprehensive income, net of deferred income tax	(1,461)						(1,461)
Foreign currency translation adjustments	(11,177)							(11,177)
Foreign currency translation adjustments attributable to noncontrolling interests								0
Shares repurchased for treasury									(372,744)
Balance at end of period at Jun. 30, 2015	6,137,515	325,000	576	437,533	7,242,728	66,441	110,360	(43,919)	(1,934,763)
Non-redeemable noncontrolling interests, end of period at Jun. 30, 2015	794,880
Total shareholders’ equity at Jun. 30, 2015	6,932,395
Net income	125,819
Net (income) loss attributable to noncontrolling interests	(10,029)
Preferred share dividends	(5,485)
Portion of other-than-temporary impairment losses recognized in other comprehensive income, net of deferred income tax	(13)
Foreign currency translation adjustments	11,580
Balance at end of period at Jun. 30, 2015	6,137,515	325,000	576	437,533	7,242,728	66,441	110,360	(43,919)	(1,934,763)
Non-redeemable noncontrolling interests, end of period at Jun. 30, 2015	794,880
Total shareholders’ equity at Jun. 30, 2015	6,932,395
Balance at beginning of year at Dec. 31, 2015	6,204,881	325,000	577	467,339	7,370,371	(16,502)	50,085	(66,587)	(1,941,904)
Common shares issued, net			4	8,265
Exercise of stock options				5,143
Amortization of share-based compensation				35,769
Other				1,426
Net income	424,984				424,984
Net (income) loss attributable to noncontrolling interests	(59,131)				(59,131)
Preferred share dividends	(10,969)				(10,969)
Unrealized holding gains (losses) arising during period, net of reclassification adjustment							181,124
Portion of other-than-temporary impairment losses recognized in other comprehensive income, net of deferred income tax	(150)						(150)
Foreign currency translation adjustments	(838)							(838)
Foreign currency translation adjustments attributable to noncontrolling interests								200
Shares repurchased for treasury									(86,786)
Balance at end of period at Jun. 30, 2016	6,703,922	325,000	581	517,942	7,725,255	163,834	231,059	(67,225)	(2,028,690)
Non-redeemable noncontrolling interests, end of period at Jun. 30, 2016	788,589
Total shareholders’ equity at Jun. 30, 2016	7,492,511
Net income	249,357
Net (income) loss attributable to noncontrolling interests	(38,302)
Preferred share dividends	(5,485)
Portion of other-than-temporary impairment losses recognized in other comprehensive income, net of deferred income tax	(52)
Foreign currency translation adjustments	(18,151)
Balance at end of period at Jun. 30, 2016	6,703,922	$ 325,000	$ 581	$ 517,942	$ 7,725,255	$ 163,834	$ 231,059	$ (67,225)	$ (2,028,690)
Non-redeemable noncontrolling interests, end of period at Jun. 30, 2016	788,589
Total shareholders’ equity at Jun. 30, 2016	$ 7,492,511

Unaudited Consolidated Stateme7

Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating Activities
Net income	$ 424,984	$ 434,576
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized (gains) losses	(126,337)	(60,818)
Net impairment losses recognized in earnings	12,982	6,912
Equity in net income or loss of investment funds accounted for using the equity method and other income or loss	11,161	(10,349)
Share-based compensation	35,769	36,044
Changes in:
Reserve for losses and loss adjustment expenses, net of unpaid losses and loss adjustment expenses recoverable	186,199	91,616
Unearned premiums, net of prepaid reinsurance premiums	187,234	156,873
Premiums receivable	(278,814)	(206,642)
Deferred acquisition costs, net	(33,450)	(39,009)
Reinsurance balances payable	73,712	19,657
Other liabilities	56,314	(94,841)
Other items	(8,530)	51,180
Net Cash Provided By Operating Activities	541,224	385,199
Investing Activities
Purchases of fixed maturity investments	(17,541,731)	(14,641,391)
Purchases of equity securities	(212,678)	(288,535)
Purchases of other investments	(650,613)	(779,678)
Proceeds from sales of fixed maturity investments	16,978,549	14,333,436
Proceeds from sales of equity securities	337,619	272,343
Proceeds from sales, redemptions and maturities of other investments	636,535	587,650
Proceeds from redemptions and maturities of fixed maturity investments	370,980	474,984
Net settlements of derivative instruments	45,174	19,006
Proceeds from investment in joint venture	0	40,000
Net (purchases) sales of short-term investments	(304,460)	3,707
Change in cash collateral related to securities lending	(18,715)	(18,329)
Purchase of business, net of cash acquired	(1,460)	818
Purchases of fixed assets	(8,284)	(6,396)
Change in other assets	13,416	(36,769)
Net Cash Provided By (Used For) Investing Activities	(355,668)	(39,154)
Financing Activities
Purchases of common shares under share repurchase program	(75,256)	(361,877)
Proceeds from common shares issued, net	(1,487)	2,178
Proceeds from borrowings	46,000	0
Repayments of borrowings	(179,171)	0
Change in cash collateral related to securities lending	18,715	18,329
Dividends paid to redeemable noncontrolling interests	(8,994)	(9,313)
Other	(2,223)	55,018
Preferred dividends paid	(10,969)	(10,969)
Net Cash Provided By (Used For) Financing Activities	(213,385)	(306,634)
Effects of exchange rate changes on foreign currency cash	(8,906)	(39)
Increase (decrease) in cash	(36,735)	39,372
Cash beginning of year	553,326	485,702
Cash end of period	516,591	525,074
Income taxes paid	26,619	25,992
Interest paid	$ 31,524	$ 25,076

General

General	6 Months Ended
	Jun. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
General	General Arch Capital Group Ltd. (“ACGL”) is a Bermuda public limited liability company which provides insurance and reinsurance on a worldwide basis through its wholly-owned subsidiaries. As used herein, the “Company” means ACGL and its subsidiaries. The Company’s consolidated financial statements include the results of Watford Holdings Ltd. and its wholly owned subsidiaries (“Watford Re”). See Note 3 . 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 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, 2015 (“2015 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 Pronouncement

Recent Accounting Pronouncements	6 Months Ended
	Jun. 30, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Issued Accounting Standards Adopted The Company adopted a new accounting standard in the 2016 first quarter that provided targeted improvements to consolidation guidance for limited partnerships and other similarly structured entities. The adoption of this standard resulted in the Company concluding that it no longer had a variable interest in Alternative Re Ltd. and, as a result, no longer is required to consolidate Alternative Re Ltd. in its financial statements. Alternative Re Ltd. is a Bermuda-domiciled company that provides collateralized segregated accounts to its clients. The Company applied this new standard on a modified retrospective basis as of January 1, 2016. Such adoption did not impact the Company’s shareholders’ equity or net income. The adoption of the new standard also resulted in a review of certain funds within the Company’s investment portfolio where the Company has a limited partnership interest. See Note 6 for disclosures on limited partnership interests. The Company also adopted new accounting guidance pertaining to hybrid instruments. The new guidance clarified the evaluation of whether the nature of a host contract within a hybrid instrument issued in the form of a share is more akin to debt or equity. The Company has adopted this new guidance on a modified retrospective basis as of January 1, 2016. Based on a review of hybrid instruments issued in the form of a share (both held in its investment portfolio and issued as part of capital raising), the Company determined the new accounting guidance had no impact on the classification or accounting for its existing hybrid instruments. Recently Issued Accounting Standards Not Yet Adopted An accounting standard was issued in the 2015 second quarter requiring new disclosures about the reserve for losses and loss adjustment expenses for short-duration insurance contracts. These disclosures will provide additional insight into an insurance entity’s ability to underwrite and anticipate costs associated with claims. This accounting guidance is effective for the 2016 annual reporting period and interim periods thereafter and should be applied retrospectively. The Company is assessing the impact the implementation of this standard will have on the disclosures included in its consolidated financial statements. A new accounting standard was issued in the 2016 first quarter to improve and simplify the accounting for employee share-based payment transactions. The new standard provides simplifications with respect to income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows for these types of transactions. The standard is effective in the 2017 first quarter and early adoption is permitted. The application of the new standard is dependent on the specific area that is amended. The Company is assessing the impact the implementation of this standard will have on its consolidated financial statements. In the 2016 first quarter, new accounting guidance was issued pertaining to the accounting for leases by a lessee. The new accounting guidance requires that the lessee recognize an asset and a liability for leases with a lease term greater than 12 months regardless of whether the lease is classified as operating or financing. Under current accounting, operating leases are not reflected in the balance sheet. This accounting guidance is effective for the 2019 first quarter, though early application is permitted, and should be applied on a modified retrospective basis. The Company is assessing the impact the implementation of this standard will have on its consolidated financial statements. A new accounting standard was issued in the 2016 second quarter that changes how entities will measure credit losses for most financial assets and certain other instruments that aren’t measured at fair value through net income. The standard requires an entity to estimate its lifetime “expected credit loss” and record an allowance that, when deducted from the amortized cost basis of the financial asset, presents the net amount expected to be collected on the financial asset. This accounting guidance is effective for the 2020 first quarter, though early application is permitted in the 2019 first quarter, and should be applied on a modified retrospective basis for the majority of the provisions. The Company is assessing the impact the implementation of this standard will have on its consolidated financial statements.

Variable Interest Entities and

Variable Interest Entities and Noncontrolling Interests	6 Months Ended
	Jun. 30, 2016
Noncontrolling Interest [Abstract]
Variable Interest Entity and Noncontrolling Interests	Variable Interest Entities and Noncontrolling Interests A variable interest entity (“VIE”) refers to an entity that has characteristics such as (i) insufficient equity at risk to allow the entity to finance its activities without additional financial support or (ii) instances where the equity investors, as a group, do not have characteristics of a controlling financial interest. The primary beneficiary of a VIE is defined as the variable interest holder that is determined to have the controlling financial interest as a result of having both (i) the power to direct the activities of a VIE that most significantly impact the economic performance of the VIE and (ii) the obligation to absorb losses or right to receive benefits from the VIE that could potentially be significant to the VIE. If a company is determined to be the primary beneficiary, it is required to consolidate the VIE in its financial statements. Watford Holdings Ltd. In March 2014, the Company invested $100.0 million and acquired approximately 11% of Watford Holdings Ltd.’s common equity and a warrant to purchase additional common equity. Watford Holdings Ltd. is the parent of Watford Re Ltd., a multi-line Bermuda reinsurance company (together with Watford Holdings Ltd., “Watford Re”). Watford Re is considered a VIE and the Company concluded that it is the primary beneficiary of Watford Re. As such, the results of Watford Re are included in the Company’s consolidated financial statements. The Company does not guarantee or provide credit support for Watford Re, and the Company’s financial exposure to Watford Re is limited to its investment in Watford Re’s 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 Re are reported: June 30, December 31, 2016 2015 Assets Investments accounted for using the fair value option $ 1,677,836 $ 1,617,107 Cash 74,525 108,550 Accrued investment income 16,329 19,249 Premiums receivable 197,062 162,263 Reinsurance recoverable on unpaid and paid losses 16,675 14,135 Prepaid reinsurance premiums 10,602 11,129 Deferred acquisition costs, net 80,304 75,443 Receivable for securities sold 40,467 34,095 Other assets 92,935 80,361 Total assets of consolidated VIE $ 2,206,735 $ 2,122,332 Liabilities Reserves for losses and loss adjustment expenses $ 404,653 $ 290,997 Unearned premiums 260,721 249,980 Reinsurance balances payable 12,872 14,005 Revolving credit agreement borrowings 297,830 430,434 Payable for securities purchased 34,729 33,062 Other liabilities 89,593 53,624 Total liabilities of consolidated VIE $ 1,100,398 $ 1,072,102 Redeemable noncontrolling interests $ 220,066 $ 219,882 For the six months ended June 30, 2016 , Watford Re generated $131.0 million of cash provided by operating activities, $13.8 million of cash used for investing activities and $148.2 million of cash used for financing activities, compared to $137.8 million of cash provided by operating activities, $134.9 million of cash used for investing activities and $40.3 million of cash provided by financing activities for the six months ended June 30, 2015 . Non-redeemable noncontrolling interests The Company accounts for the portion of Watford Re’s common equity attributable to third party investors in the shareholders’ equity section of its consolidated balance sheets. The noncontrolling ownership in Watford Re’s common shares was approximately 89% at June 30, 2016 . The portion of Watford Re’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: June 30, 2016 2015 Three Months Ended Balance, beginning of period $ 754,915 $ 789,594 Amounts attributable to noncontrolling interests 33,716 5,286 Foreign currency translation adjustments attributable to noncontrolling interests (42 ) — Balance, end of period $ 788,589 $ 794,880 Six Months Ended Balance, beginning of year $ 738,831 $ 769,081 Amounts attributable to noncontrolling interests 49,958 25,799 Foreign currency translation adjustments attributable to noncontrolling interests (200 ) — Balance, end of period $ 788,589 $ 794,880 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 9,065,200 cumulative redeemable preference shares (“Watford Preference Shares”) issued in March 2014 with a par value of $0.01 per share and a liquidation preference of $25.00 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. The following table sets forth activity in the redeemable non-controlling interests: June 30, 2016 2015 Three Months Ended Balance, beginning of period $ 205,274 $ 219,604 Shares acquired by the Company — (14,700 ) Accretion of preference share issuance costs 92 92 Balance, end of period $ 205,366 $ 204,996 Six Months Ended Balance, beginning of year $ 205,182 $ 219,512 Shares acquired by the Company — (14,700 ) Accretion of preference share issuance costs 184 184 Balance, end of period $ 205,366 $ 204,996 The portion of Watford Re’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: June 30, 2016 2015 Three Months Ended Amounts attributable to non-redeemable noncontrolling interests $ (33,716 ) $ (5,286 ) Dividends attributable to redeemable noncontrolling interests (4,586 ) (4,743 ) Net (income) loss attributable to noncontrolling interests $ (38,302 ) $ (10,029 ) Six Months Ended Amounts attributable to non-redeemable noncontrolling interests $ (49,958 ) $ (25,799 ) Dividends attributable to redeemable noncontrolling interests (9,173 ) (9,651 ) Net (income) loss attributable to noncontrolling interests $ (59,131 ) $ (35,450 )

Earnings Per Common Share

Earnings Per Common Share	6 Months Ended
	Jun. 30, 2016
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 Six Months Ended June 30, June 30, 2016 2015 2016 2015 Numerator: Net income $ 249,357 $ 125,819 $ 424,984 $ 434,576 Net (income) loss attributable to noncontrolling interests (38,302 ) (10,029 ) (59,131 ) (35,450 ) Net income available to Arch 211,055 115,790 365,853 399,126 Preferred dividends (5,485 ) (5,485 ) (10,969 ) (10,969 ) Net income available to Arch common shareholders $ 205,570 $ 110,305 $ 354,884 $ 388,157 Denominator: Weighted average common shares outstanding — basic 120,599,060 121,719,214 120,513,620 122,957,384 Effect of dilutive common share equivalents: Nonvested restricted shares 1,295,342 1,258,741 1,374,272 1,334,633 Stock options (1) 2,471,194 2,907,465 2,537,234 2,864,696 Weighted average common shares and common share equivalents outstanding — diluted 124,365,596 125,885,420 124,425,126 127,156,713 Earnings per common share: Basic $ 1.70 $ 0.91 $ 2.94 $ 3.16 Diluted $ 1.65 $ 0.88 $ 2.85 $ 3.05 (1) 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 2016 second quarter and 2015 second quarter , the number of stock options excluded were 575,931 and 1,009,113 , respectively. For the six months ended June 30, 2016 and 2015 , the number of stock options excluded were 1,027,784 and 1,187,162 , respectively.

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2016
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 Chairman and Chief Executive Officer, the President and Chief Operating Officer, and the Chief Financial Officer of ACGL. 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 results of Arch Mortgage Insurance Company (“Arch MI U.S.”) and Arch Mortgage Insurance Designated Activity Company, leading providers of mortgage insurance products and services to the U.S. and European markets, respectively. Arch MI U.S. is approved as an eligible mortgage insurer by Federal National Mortgage Association (“Fannie Mae”) and Federal Home Loan Mortgage Corporation (“Freddie Mac”), each a government sponsored enterprise, or “GSE.” The mortgage segment also includes GSE credit risk-sharing transactions and mortgage reinsurance for the U.S. and Australian markets. The corporate (non-underwriting) segment results include net investment income, other income (loss), corporate expenses, interest expense, 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, income taxes and items related to the Company’s non-cumulative preferred shares. Such amounts exclude the results of the ‘other’ segment. The ‘other’ segment includes the results of Watford Re (see Note 3 ). Watford Re has its own management and board of directors that is responsible for the overall profitability of the ‘other’ segment. 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 common shareholders: Three Months Ended June 30, 2016 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 762,043 $ 412,053 $ 118,434 $ 1,292,199 $ 109,285 $ 1,329,936 Premiums ceded (246,875 ) (119,951 ) (6,969 ) (373,464 ) (4,457 ) (306,373 ) Net premiums written 515,168 292,102 111,465 918,735 104,828 1,023,563 Change in unearned premiums 12,482 (846 ) (44,953 ) (33,317 ) 15,739 (17,578 ) Net premiums earned 527,650 291,256 66,512 885,418 120,567 1,005,985 Other underwriting income — 20,118 4,137 24,255 969 25,224 Losses and loss adjustment expenses (354,633 ) (146,091 ) (366 ) (501,090 ) (83,502 ) (584,592 ) Acquisition expenses, net (77,317 ) (55,796 ) (8,523 ) (141,636 ) (33,645 ) (175,281 ) Other operating expenses (92,371 ) (37,115 ) (23,991 ) (153,477 ) (6,113 ) (159,590 ) Underwriting income (loss) $ 3,329 $ 72,372 $ 37,769 113,470 (1,724 ) 111,746 Net investment income 70,397 17,941 88,338 Net realized gains (losses) 40,927 27,291 68,218 Net impairment losses recognized in earnings (5,343 ) — (5,343 ) Equity in net income (loss) of investment funds accounted for using the equity method 8,737 — 8,737 Other income (loss) (7 ) — (7 ) Corporate expenses (17,200 ) — (17,200 ) Interest expense (12,432 ) (3,231 ) (15,663 ) Net foreign exchange gains (losses) 22,461 2,201 24,662 Income (loss) before income taxes 221,010 42,478 263,488 Income tax expense (14,131 ) — (14,131 ) Net income (loss) 206,879 42,478 249,357 Dividends attributable to redeemable noncontrolling interests — (4,586 ) (4,586 ) Amounts attributable to noncontrolling interests — (33,716 ) (33,716 ) Net income (loss) available to Arch 206,879 4,176 211,055 Preferred dividends (5,485 ) — (5,485 ) Net income (loss) available to Arch common shareholders $ 201,394 $ 4,176 $ 205,570 Underwriting Ratios Loss ratio 67.2 % 50.2 % 0.6 % 56.6 % 69.3 % 58.1 % Acquisition expense ratio 14.7 % 19.2 % 12.8 % 16.0 % 27.9 % 17.4 % Other operating expense ratio 17.5 % 12.7 % 36.1 % 17.3 % 5.1 % 15.9 % Combined ratio 99.4 % 82.1 % 49.5 % 89.9 % 102.3 % 91.4 % Goodwill and intangible assets $ 27,457 $ 1,440 $ 59,430 $ 88,327 $ — $ 88,327 (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. Three Months Ended June 30, 2015 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 744,810 $ 342,101 $ 68,572 $ 1,155,253 $ 127,954 $ 1,199,209 Premiums ceded (235,743 ) (89,446 ) (6,902 ) (331,861 ) (7,766 ) (255,629 ) Net premiums written 509,067 252,655 61,670 823,392 120,188 943,580 Change in unearned premiums 758 21,310 (9,211 ) 12,857 (12,999 ) (142 ) Net premiums earned 509,825 273,965 52,459 836,249 107,189 943,438 Other underwriting income 521 2,658 3,686 6,865 852 7,717 Losses and loss adjustment expenses (320,926 ) (111,183 ) (9,639 ) (441,748 ) (77,678 ) (519,426 ) Acquisition expenses, net (76,723 ) (58,360 ) (10,200 ) (145,283 ) (30,142 ) (175,425 ) Other operating expenses (89,054 ) (39,007 ) (19,679 ) (147,740 ) (3,450 ) (151,190 ) Underwriting income (loss) $ 23,643 $ 68,073 $ 16,627 108,343 (3,229 ) 105,114 Net investment income 67,171 19,792 86,963 Net realized gains (losses) (26,860 ) (8,865 ) (35,725 ) Net impairment losses recognized in earnings (1,113 ) — (1,113 ) Equity in net income (loss) of investment funds accounted for using the equity method 16,167 — 16,167 Other income (loss) 2,205 — 2,205 Corporate expenses (17,418 ) — (17,418 ) Interest expense (4,011 ) — (4,011 ) Net foreign exchange gains (losses) (22,571 ) 2,988 (19,583 ) Income (loss) before income taxes 121,913 10,686 132,599 Income tax expense (6,780 ) — (6,780 ) Net income (loss) 115,133 10,686 125,819 Dividends attributable to redeemable noncontrolling interests — (4,743 ) (4,743 ) Amounts attributable to noncontrolling interests — (5,286 ) (5,286 ) Net income (loss) available to Arch 115,133 657 115,790 Preferred dividends (5,485 ) — (5,485 ) Net income (loss) available to Arch common shareholders $ 109,648 $ 657 $ 110,305 Underwriting Ratios Loss ratio 62.9 % 40.6 % 18.4 % 52.8 % 72.5 % 55.1 % Acquisition expense ratio 15.0 % 21.3 % 19.4 % 17.4 % 28.1 % 18.6 % Other operating expense ratio 17.5 % 14.2 % 37.5 % 17.7 % 3.2 % 16.0 % Combined ratio 95.4 % 76.1 % 75.3 % 87.9 % 103.8 % 89.7 % Goodwill and intangible assets $ 30,968 $ 2,420 $ 69,130 $ 102,518 $ — $ 102,518 (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. Six Months Ended June 30, 2016 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 1,560,596 $ 893,443 $ 229,714 $ 2,683,260 $ 257,891 $ 2,767,902 Premiums ceded (495,664 ) (280,517 ) (11,736 ) (787,424 ) (8,929 ) (623,104 ) Net premiums written 1,064,932 612,926 217,978 1,895,836 248,962 2,144,798 Change in unearned premiums (24,193 ) (60,462 ) (89,701 ) (174,356 ) (12,878 ) (187,234 ) Net premiums earned 1,040,739 552,464 128,277 1,721,480 236,084 1,957,564 Other underwriting income — 20,443 7,930 28,373 1,898 30,271 Losses and loss adjustment expenses (678,242 ) (257,689 ) (8,995 ) (944,926 ) (162,615 ) (1,107,541 ) Acquisition expenses, net (151,671 ) (110,583 ) (16,908 ) (279,162 ) (66,584 ) (345,746 ) Other operating expenses (178,232 ) (73,570 ) (48,606 ) (300,408 ) (11,451 ) (311,859 ) Underwriting income (loss) $ 32,594 $ 131,065 $ 61,698 225,357 (2,668 ) 222,689 Net investment income 140,806 41,267 182,073 Net realized gains (losses) 72,789 32,753 105,542 Net impairment losses recognized in earnings (12,982 ) — (12,982 ) Equity in net income (loss) of investment funds accounted for using the equity method 15,392 — 15,392 Other income (loss) (32 ) — (32 ) Corporate expenses (26,583 ) — (26,583 ) Interest expense (25,059 ) (6,711 ) (31,770 ) Net foreign exchange gains (losses) 420 676 1,096 Income (loss) before income taxes 390,108 65,317 455,425 Income tax expense (30,441 ) — (30,441 ) Net income (loss) 359,667 65,317 424,984 Dividends attributable to redeemable noncontrolling interests — (9,173 ) (9,173 ) Amounts attributable to noncontrolling interests — (49,958 ) (49,958 ) Net income (loss) available to Arch 359,667 6,186 365,853 Preferred dividends (10,969 ) — (10,969 ) Net income (loss) available to Arch common shareholders $ 348,698 $ 6,186 $ 354,884 Underwriting Ratios Loss ratio 65.2 % 46.6 % 7.0 % 54.9 % 68.9 % 56.6 % Acquisition expense ratio 14.6 % 20.0 % 13.2 % 16.2 % 28.2 % 17.7 % Other operating expense ratio 17.1 % 13.3 % 37.9 % 17.5 % 4.9 % 15.9 % Combined ratio 96.9 % 79.9 % 58.1 % 88.6 % 102.0 % 90.2 % (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. Six Months Ended June 30, 2015 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 1,510,963 $ 827,213 $ 129,113 $ 2,466,931 $ 256,587 $ 2,541,231 Premiums ceded (459,893 ) (226,015 ) (15,572 ) (701,122 ) (11,821 ) (530,656 ) Net premiums written 1,051,070 601,198 113,541 1,765,809 244,766 2,010,575 Change in unearned premiums (33,331 ) (47,516 ) (10,715 ) (91,562 ) (65,311 ) (156,873 ) Net premiums earned 1,017,739 553,682 102,826 1,674,247 179,455 1,853,702 Other underwriting income 948 4,087 11,404 16,439 2,814 19,253 Losses and loss adjustment expenses (638,822 ) (223,715 ) (23,448 ) (885,985 ) (127,157 ) (1,013,142 ) Acquisition expenses, net (151,801 ) (114,964 ) (20,618 ) (287,383 ) (51,118 ) (338,501 ) Other operating expenses (177,173 ) (77,051 ) (40,048 ) (294,272 ) (5,455 ) (299,727 ) Underwriting income $ 50,891 $ 142,039 $ 30,116 223,046 (1,461 ) 221,585 Net investment income 137,459 28,498 165,957 Net realized gains 38,649 8,974 47,623 Net impairment losses recognized in earnings (6,912 ) — (6,912 ) Equity in net income (loss) of investment funds accounted for using the equity method 22,056 — 22,056 Other income (loss) 317 — 317 Corporate expenses (26,763 ) — (26,763 ) Interest expense (16,747 ) — (16,747 ) Net foreign exchange gains (losses) 44,282 2,636 46,918 Income (loss) before income taxes 415,387 38,647 454,034 Income tax expense (19,458 ) — (19,458 ) Net income (loss) 395,929 38,647 434,576 Dividends attributable to redeemable noncontrolling interests — (9,651 ) (9,651 ) Amounts attributable to noncontrolling interests — (25,799 ) (25,799 ) Net income (loss) available to Arch 395,929 3,197 399,126 Preferred dividends (10,969 ) — (10,969 ) Net income (loss) available to Arch common shareholders $ 384,960 $ 3,197 $ 388,157 Underwriting Ratios Loss ratio 62.8 % 40.4 % 22.8 % 52.9 % 70.9 % 54.7 % Acquisition expense ratio 14.9 % 20.8 % 20.1 % 17.2 % 28.5 % 18.3 % Other operating expense ratio 17.4 % 13.9 % 38.9 % 17.6 % 3.0 % 16.2 % Combined ratio 95.1 % 75.1 % 81.8 % 87.7 % 102.4 % 89.2 % (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.

Investment Information

Investment Information	6 Months Ended
	Jun. 30, 2016
Disclosure Investment Information [Abstract]
Investment Information	Investment Information At June 30, 2016 , total investable assets of $16.88 billion included $15.18 billion managed by the Company and $1.70 billion attributable to Watford Re. Available For Sale Investments The following table summarizes the fair value and cost or amortized cost of the Company’s investments classified as available for sale: Estimated Fair Value Gross Unrealized Gains Gross Unrealized Losses Cost or Amortized Cost OTTI Unrealized Losses (2) June 30, 2016 Fixed maturities (1): Corporate bonds $ 2,952,173 $ 68,437 $ (17,635 ) $ 2,901,371 $ (2,304 ) Mortgage backed securities 656,891 12,973 (1,177 ) 645,095 (3,443 ) Municipal bonds 1,897,128 47,135 (678 ) 1,850,671 — Commercial mortgage backed securities 624,391 13,854 (1,004 ) 611,541 — U.S. government and government agencies 2,701,042 33,940 (749 ) 2,667,851 — Non-U.S. government securities 1,172,745 46,672 (37,074 ) 1,163,147 — Asset backed securities 1,365,766 13,492 (5,413 ) 1,357,687 (69 ) Total 11,370,136 236,503 (63,730 ) 11,197,363 (5,816 ) Equity securities 501,916 87,768 (11,163 ) 425,311 — Other investments 182,957 19,550 (4,507 ) 167,914 — Short-term investments 853,531 351 (2,584 ) 855,764 — Total $ 12,908,540 $ 344,172 $ (81,984 ) $ 12,646,352 $ (5,816 ) December 31, 2015 Fixed maturities (1): Corporate bonds $ 2,725,729 $ 15,978 $ (60,508 ) $ 2,770,259 $ (3,553 ) Mortgage backed securities 754,870 9,872 (5,334 ) 750,332 (3,350 ) Municipal bonds 1,626,281 27,014 (1,534 ) 1,600,801 — Commercial mortgage backed securities 764,152 3,269 (6,978 ) 767,861 — U.S. government and government agencies 2,423,455 6,228 (9,978 ) 2,427,205 — Non-U.S. government securities 917,664 10,414 (39,122 ) 946,372 — Asset backed securities 1,620,506 3,307 (12,951 ) 1,630,150 (22 ) Total 10,832,657 76,082 (136,405 ) 10,892,980 (6,925 ) Equity securities 629,182 94,341 (17,796 ) 552,637 — Other investments 300,476 43,798 (4,665 ) 261,343 — Short-term investments 587,904 187 (3,425 ) 591,142 — Total $ 12,350,219 $ 214,408 $ (162,291 ) $ 12,298,102 $ (6,925 ) (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.” (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 June 30, 2016 , the net unrealized gain related to securities for which a non-credit OTTI was recognized in AOCI was $1.5 million , compared to a net unrealized loss of $1.4 million at December 31, 2015 . 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 June 30, 2016 Fixed maturities (1): Corporate bonds $ 197,372 $ (4,776 ) $ 127,233 $ (12,859 ) $ 324,605 $ (17,635 ) Mortgage backed securities 67,489 (760 ) 16,999 (417 ) 84,488 (1,177 ) Municipal bonds 109,185 (277 ) 21,887 (401 ) 131,072 (678 ) Commercial mortgage backed securities 29,312 (526 ) 29,192 (478 ) 58,504 (1,004 ) U.S. government and government agencies 112,776 (749 ) — — 112,776 (749 ) Non-U.S. government securities 299,048 (15,856 ) 137,035 (21,218 ) 436,083 (37,074 ) Asset backed securities 182,387 (3,147 ) 79,147 (2,266 ) 261,534 (5,413 ) Total 997,569 (26,091 ) 411,493 (37,639 ) 1,409,062 (63,730 ) Equity securities 156,789 (11,163 ) — — 156,789 (11,163 ) Other investments 37,943 (4,507 ) — — 37,943 (4,507 ) Short-term investments 33,404 (2,584 ) — — 33,404 (2,584 ) Total $ 1,225,705 $ (44,345 ) $ 411,493 $ (37,639 ) $ 1,637,198 $ (81,984 ) December 31, 2015 Fixed maturities (1): Corporate bonds $ 1,810,988 $ (37,445 ) $ 129,896 $ (23,063 ) $ 1,940,884 $ (60,508 ) Mortgage backed securities 487,018 (4,508 ) 48,991 (826 ) 536,009 (5,334 ) Municipal bonds 269,015 (1,303 ) 9,692 (231 ) 278,707 (1,534 ) Commercial mortgage backed securities 511,261 (6,639 ) 20,596 (339 ) 531,857 (6,978 ) U.S. government and government agencies 1,991,163 (9,978 ) — — 1,991,163 (9,978 ) Non-U.S. government securities 458,414 (13,494 ) 138,792 (25,628 ) 597,206 (39,122 ) Asset backed securities 1,217,163 (9,328 ) 134,841 (3,623 ) 1,352,004 (12,951 ) Total 6,745,022 (82,695 ) 482,808 (53,710 ) 7,227,830 (136,405 ) Equity securities 232,275 (17,796 ) — — 232,275 (17,796 ) Other investments 93,614 (4,665 ) — — 93,614 (4,665 ) Short-term investments 30,625 (3,425 ) — — 30,625 (3,425 ) Total $ 7,101,536 $ (108,581 ) $ 482,808 $ (53,710 ) $ 7,584,344 $ (162,291 ) (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.” At June 30, 2016 , on a lot level basis, approximately 1,410 security lots out of a total of approximately 6,280 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 $3.4 million . At December 31, 2015 , on a lot level basis, approximately 3,560 security lots out of a total of approximately 5,550 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 $3.1 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. June 30, 2016 December 31, 2015 Maturity Estimated Fair Value Amortized Cost Estimated Amortized Cost Due in one year or less $ 247,256 $ 244,247 $ 337,898 $ 341,595 Due after one year through five years 5,077,739 5,036,912 4,644,516 4,677,230 Due after five years through 10 years 2,772,938 2,699,463 2,214,413 2,228,638 Due after 10 years 625,155 602,418 496,302 497,174 8,723,088 8,583,040 7,693,129 7,744,637 Mortgage backed securities 656,891 645,095 754,870 750,332 Commercial mortgage backed securities 624,391 611,541 764,152 767,861 Asset backed securities 1,365,766 1,357,687 1,620,506 1,630,150 Total (1) $ 11,370,136 $ 11,197,363 $ 10,832,657 $ 10,892,980 (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 to the Company. The Company receives collateral in the form of cash or securities. Cash collateral primarily consists of short-term investments. At June 30, 2016 , the fair value of the cash collateral received on securities lending was $75.9 million and the fair value of security collateral received was $262.4 million . At December 31, 2015 , the fair value of the cash collateral received on securities lending was $52.7 million , which included $3.0 million that was reinvested in sub-prime mortgage backed securities, and the fair value of security collateral received was $336.7 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 June 30, 2016 U.S. government and government agencies $ 242,184 $ 21,539 $ 4,109 $ 26,168 $ 294,000 Corporate bonds 33,120 — — — 33,120 Equity securities 11,198 — — — 11,198 Total $ 286,502 $ 21,539 $ 4,109 $ 26,168 $ 338,318 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 $ 338,318 December 31, 2015 U.S. government and government agencies $ 235,728 $ — $ 82,286 $ 9,598 $ 327,612 Corporate bonds 55,086 — — — 55,086 Equity securities 6,722 4,424 — — 11,146 Total $ 297,536 $ 4,424 $ 82,286 $ 9,598 $ 393,844 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 $ 393,844 Other Investments The following table summarizes the Company’s other investments, including available for sale and fair value option components: June 30, December 31, Available for sale: Asian and emerging markets $ 109,767 $ 206,861 Investment grade fixed income 33,549 31,370 Credit related funds 1,698 22,512 Other 37,943 39,733 Total available for sale 182,957 300,476 Fair value option: Term loan investments (par value: $1,115,627 and $1,197,143) 1,026,543 1,108,017 Mezzanine debt funds 117,441 121,589 Credit related funds 236,184 219,049 Investment grade fixed income 65,391 63,053 Asian and emerging markets 112,265 34,761 Other (1) 107,916 124,502 Total fair value option 1,665,740 1,670,971 Total $ 1,848,697 $ 1,971,447 (1) Includes fund investments with strategies in mortgage servicing rights, transportation, infrastructure and other. 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 and liabilities which are accounted for using the fair value option: June 30, December 31, Fixed maturities $ 1,047,662 $ 936,802 Other investments 1,665,740 1,670,971 Short-term investments 344,797 285,923 Equity securities 7,830 798 Investments accounted for using the fair value option $ 3,066,029 $ 2,894,494 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.’ Based on the new accounting guidance for consolidation, the Company determined that these limited partnership interests represented variable interests in the funds because the general partner did not have a significant interest in the fund. 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: June 30, December 31, Investments accounted for using the equity method (1) $ 676,893 $ 584,158 Investments accounted for using the fair value option (2) 83,931 90,969 Total $ 760,824 $ 675,127 (1) Aggregate unfunded commitments were $794.7 million at June 30, 2016 , compared to $535.4 million at December 31, 2015 . (2) Aggregate unfunded commitments were $26.6 million at June 30, 2016 , compared to $22.7 million at December 31, 2015 . Net Investment Income The components of net investment income were derived from the following sources: June 30, 2016 2015 Three Months Ended Fixed maturities $ 77,994 $ 71,275 Term loan investments 18,608 18,033 Equity securities (dividends) 3,663 2,578 Short-term investments 816 225 Other (1) 8,260 10,489 Gross investment income 109,341 102,600 Investment expenses (21,003 ) (15,637 ) Net investment income $ 88,338 $ 86,963 Six Months Ended Fixed maturities $ 151,667 $ 139,871 Term loan investments 38,620 32,777 Equity securities (dividends) 7,098 5,257 Short-term investments 1,312 421 Other (1) 22,003 23,236 Gross investment income 220,700 201,562 Investment expenses (38,627 ) (35,605 ) Net investment income $ 182,073 $ 165,957 (1) Includes income distributions from investment funds and other items. Net Realized Gains (Losses) Net realized gains (losses) were as follows, excluding other than-temporary impairment provision. June 30, 2016 2015 Three Months Ended Available for sale securities: Gross gains on investment sales $ 74,695 $ 82,233 Gross losses on investment sales (43,293 ) (58,974 ) Change in fair value of assets and liabilities accounted for using the fair value option: Fixed maturities 18,632 (5,191 ) Other investments 13,136 785 Equity securities 401 (69 ) Short-term investments (621 ) (4,375 ) Derivative instruments (1) 20,334 (41,496 ) Other (2) (15,066 ) (8,638 ) Net realized gains (losses) $ 68,218 $ (35,725 ) Six Months Ended Available for sale securities: Gross gains on investment sales $ 182,514 $ 179,824 Gross losses on investment sales (106,424 ) (114,134 ) Change in fair value of assets and liabilities accounted for using the fair value option: Fixed maturities 18,299 (8,493 ) Other investments (8,412 ) 7,072 Equity securities 437 (71 ) Short-term investments (1,043 ) 1,471 Derivative instruments (1) 41,066 (4,820 ) Other (2) (20,895 ) (13,226 ) Net realized gains (losses) $ 105,542 $ 47,623 (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 $8.7 million of equity in net income related to investment funds accounted for using the equity method in the 2016 second quarter , compared to $16.2 million of equity in net income for the 2015 second quarter , and $15.4 million of equity in net income related to investment funds accounted for using the equity method for the six months ended June 30, 2016 , compared to $22.1 million of equity in net income for the 2015 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. Other-Than-Temporary Impairments 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: June 30, 2016 2015 Three Months Ended Fixed maturities: Mortgage backed securities $ (82 ) $ (326 ) Corporate bonds (775 ) (10 ) Non-U.S. government securities (51 ) — Asset backed securities (2,500 ) — Total (3,408 ) (336 ) Short-term investments — — Equity securities (1,935 ) (124 ) Other investments — (653 ) Net impairment losses recognized in earnings $ (5,343 ) $ (1,113 ) Six Months Ended Fixed maturities: Mortgage backed securities $ (555 ) $ (1,398 ) Corporate bonds (5,655 ) (1,986 ) Non-U.S. government securities (232 ) — Asset backed securities (2,506 ) — Total (8,948 ) (3,384 ) Short-term investments — (2,341 ) Equity securities (3,037 ) (253 ) Other investments (997 ) (934 ) Net impairment losses recognized in earnings $ (12,982 ) $ (6,912 ) A description of the methodology and significant inputs used to measure the amount of net impairment losses recognized in earnings in the 2016 periods is as follows: • Corporate bonds — the Company reviewed the business prospects, credit ratings, estimated loss given default factors, foreign currency impacts and information received from asset managers and rating agencies for certain corporate bonds. Impairment losses primarily resulted from reductions on non-investment grade corporate bonds in the energy sector, reflecting current market conditions; • Equity securities — the Company utilized information received from asset managers on common stocks, including the business prospects, recent events, industry and market data and other factors. Impairment losses were primarily on equities which were in an unrealized loss position for a significant length of time; • Asset backed securities — the Company utilized underlying data provided by asset managers, cash flow projections and additional information from credit agencies in order to determine an expected recovery value for each security. Impairment losses primarily reflected a reduction on one security following an analysis of expected cash flows. • Other investments — the Company utilized information received from asset managers on investment funds, including the business prospects, recent events, industry and market data and other factors. Impairment losses reflected a reduction on one fund which was in an unrealized loss position for a significant length of time; • Mortgage backed securities — the Company utilized underlying data provided by asset managers, cash flow projections and additional information from credit agencies in order to determine an expected recovery value for each security. The analysis includes a review of cash flow projections under base case and stress case scenarios which modify the expected default expectations and loss severities and slow down prepayment assumptions. The significant inputs in the models include the expected default rates, delinquency rates and foreclosure costs. Impairment losses resulted from relatively small adjustments on a number of mortgage backed securities. The Company believes that the $5.8 million of OTTI included in accumulated other comprehensive income at June 30, 2016 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 June 30, 2016 , 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: June 30, 2016 2015 Three Months Ended Balance at start of period $ 18,291 $ 24,344 Credit loss impairments recognized on securities not previously impaired 287 281 Credit loss impairments recognized on securities previously impaired — 55 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 (3,731 ) (3,774 ) Balance at end of period $ 14,847 $ 20,906 Six Months Ended Balance at start of year $ 26,875 $ 20,196 Credit loss impairments recognized on securities not previously impaired 1,350 4,770 Credit loss impairments recognized on securities previously impaired 522 134 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 (13,900 ) (4,194 ) Balance at end of period $ 14,847 $ 20,906 Restricted Assets The Company is required to maintain assets on deposit, which primarily consist of fixed maturities, with various regulatory authorities to support its insurance and reinsurance operations. The Company’s insurance and reinsurance subsidiaries maintain assets in trust accounts as collateral for insurance and reinsurance 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 9 for further details. The following table details the value of the Company’s restricted assets: June 30, December 31, Assets used for collateral or guarantees: Affiliated transactions $ 3,903,933 $ 3,810,104 Third party agreements 1,598,266 1,286,257 Deposits with U.S. regulatory authorities 477,429 391,458 Deposits with non-U.S. regulatory authorities 47,429 38,230 Total restricted assets $ 6,027,057 $ 5,526,049

Fair Value

Fair Value	6 Months Ended
	Jun. 30, 2016
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 June 30, 2016 . 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 $16.20 billion of financial assets and liabilities measured at fair value at June 30, 2016 , approximately $379.5 million , or 2.4% , were priced using non-binding broker-dealer quotes. Of the $15.40 billion of financial assets and liabilities measured at fair value at December 31, 2015 , approximately $317.8 million , or 2.1% , 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. • 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. • 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. 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. 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. 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 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 June 30, 2016 : 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 $ 2,952,173 $ — $ 2,934,868 $ 17,305 Mortgage backed securities 656,891 — 656,891 — Municipal bonds 1,897,128 — 1,897,128 — Commercial mortgage backed securities 624,391 — 624,391 — U.S. government and government agencies 2,701,042 2,558,706 142,336 — Non-U.S. government securities 1,172,745 — 1,172,745 — Asset backed securities 1,365,766 — 1,316,555 49,211 Total 11,370,136 2,558,706 8,744,914 66,516 Equity securities 501,916 500,158 1,758 — Short-term investments 853,531 837,202 16,329 — Other investments 79,174 79,174 — — Other investments measured at net asset value (2) 103,783 Total other investments 182,957 79,174 — — Derivative instruments (4) 30,625 — 30,625 — Fair value option: Corporate bonds 754,034 — 754,034 — Non-U.S. government bonds 101,492 — 101,492 — Mortgage backed securities 17,560 — 17,560 — Asset backed securities 22,850 — 22,850 — U.S. government and government agencies 151,726 151,726 — — Short-term investments 344,797 344,797 — — Equity securities 7,830 7,090 740 — Other investments 1,082,309 55,766 1,026,543 — Other investments measured at net asset value (2) 583,431 Total 3,066,029 559,379 1,923,219 — Total assets measured at fair value $ 16,005,194 $ 4,534,619 $ 10,716,845 $ 66,516 Liabilities measured at fair value: Contingent consideration liabilities $ (111,670 ) $ — $ — $ (111,670 ) Securities sold but not yet purchased (3) (54,668 ) — (54,668 ) — Derivative instruments (4) (26,428 ) — (26,428 ) — Total liabilities measured at fair value $ (192,766 ) $ — $ (81,096 ) $ (111,670 ) (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 , “Investment Information—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 , “Derivative Instruments.” The following table presents the Company’s financial assets and liabilities measured at fair value by level at December 31, 2015 : 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 $ 2,725,729 $ — $ 2,709,361 $ 16,368 Mortgage backed securities 754,870 — 754,870 — Municipal bonds 1,626,281 — 1,626,281 — Commercial mortgage backed securities 764,152 — 764,152 — U.S. government and government agencies 2,423,455 2,378,662 44,793 — Non-U.S. government securities 917,664 — 917,664 — Asset backed securities 1,620,506 — 1,563,006 57,500 Total 10,832,657 2,378,662 8,380,127 73,868 Equity securities 629,182 627,441 1,741 — Short-term investments 587,904 572,604 15,300 — Other investments 99,159 99,159 — — Other investments measured at net asset value (2) 201,317 Total other investments 300,476 99,159 — — Derivative instruments (4) 20,022 — 20,022 — Fair value option: Corporate bonds 771,733 — 771,733 — Non-U.S. government bonds 81,824 — 81,824 — Mortgage backed securities 57,687 — 57,687 — Asset backed securities 25,444 — 25,444 — U.S. government and government agencies 114 114 — — Short-term investments 285,923 285,923 — — Equity securities 798 798 — — Other investments 1,176,312 68,295 1,108,017 — Other investments measured at net asset value (2) 494,659 Total 2,894,494 355,130 2,044,705 — Total assets measured at fair value $ 15,264,735 $ 4,032,996 $ 10,461,895 $ 73,868 Liabilities measured at fair value: Contingent consideration liabilities $ (96,048 ) $ — $ — $ (96,048 ) Securities sold but not yet purchased (3) (30,583 ) — (30,583 ) — Derivative instruments (4) (11,863 ) — (11,863 ) — Total liabilities measured at fair value $ (138,494 ) $ — $ (42,446 ) $ (96,048 ) (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 , “Investment Information—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 , “Derivative Instruments.” 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 Asset Backed Securities Corporate Bonds Total Contingent Consideration Liabilities Three Months Ended June 30, 2016 Balance at beginning of period $ 57,500 $ 15,166 $ 72,666 $ (100,710 ) Total gains or (losses) (realized/unrealized) Included in earnings (1) (2,500 ) 1,363 (1,137 ) (10,923 ) Included in other comprehensive income — — — (37 ) Purchases, issuances, sales and settlements Purchases — 776 776 — Issuances — — — — Sales — — — — Settlements (5,789 ) — (5,789 ) — Transfers in and/or out of Level 3 — — — — Balance at end of period $ 49,211 $ 17,305 $ 66,516 $ (111,670 ) Three Months Ended June 30, 2015 Balance at beginning of period $ 57,500 $ — $ 57,500 $ (66,461 ) Total gains or (losses) (realized/unrealized) Included in earnings (1) — — — (4,795 ) Included in other comprehensive income — — — — Purchases, issuances, sales and settlements Purchases — — — — Issuances — — — — Sales — — — — Settlements — — — — Transfers in and/or out of Level 3 — — — — Balance at end of period $ 57,500 $ — $ 57,500 $ (71,256 ) Six Months Ended June 30, 2016 Balance at beginning of year $ 57,500 $ 16,368 $ 73,868 $ (96,048 ) Total gains or (losses) (realized/unrealized) Included in earnings (1) (2,500 ) 161 (2,339 ) (16,121 ) Included in other comprehensive income — — — (37 ) Purchases, issuances, sales and settlements Purchases — 776 776 — Issuances — — — — Sales — — — — Settlements (5,789 ) — (5,789 ) 536 Transfers in and/or out of Level 3 — — — — Balance at end of period $ 49,211 $ 17,305 $ 66,516 $ (111,670 ) Six Months Ended June 30, 2015 Balance at beginning of year $ 57,500 $ — $ 57,500 $ (61,845 ) Total gains or (losses) (realized/unrealized) Included in earnings (1) — — — (8,343 ) Included in other comprehensive income — — — — Purchases, issuances, sales and settlements Purchases — — — — Issuances — — — (1,068 ) Sales — — — — Settlements — — — — Transfers in and/or out of Level 3 — — — — Balance at end of period $ 57,500 $ — $ 57,500 $ (71,256 ) (1) Gains or losses on asset backed securities were included in net impairment losses recognized in earnings while gains or losses on corporate bonds and contingent consideration liabilities 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 June 30, 2016 , due to their respective short maturities. As these financial instruments are not actively traded, their respective fair values are classified within Level 2. At June 30, 2016 , the senior notes of ACGL were carried at their cost, net of debt issuance costs, of $296.9 million and had a fair value of $428.0 million while the senior notes of Arch-U.S. were carried at their cost, net of debt issuance costs, of $494.5 million and had a fair value of $602.8 million . The fair values of the senior notes were obtained from a third party pricing service and are based on observable market inputs. As such, the fair value of the senior notes is classified within Level 2.

Derivative Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 2016
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 Liability Derivatives Notional Value (1) June 30, 2016 Futures contracts (2) $ 1,208 $ (1,673 ) $ 2,287,791 Foreign currency forward contracts (2) 17,032 (18,718 ) 1,436,006 TBAs (3) 121,760 (117,673 ) 226,299 Other (2) 12,385 (6,037 ) 1,938,497 Total $ 152,385 $ (144,101 ) December 31, 2015 Futures contracts (2) $ 2,816 $ (1,202 ) $ 1,797,115 Foreign currency forward contracts (2) 9,336 (6,344 ) 773,619 TBAs (3) 6,525 — 6,316 Other (2) 7,870 (4,317 ) 1,694,935 Total $ 26,547 $ (11,863 ) (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 June 30, 2016 or December 31, 2015 . 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. At June 30, 2016 , asset derivatives and liability derivatives of $152.2 million and $144.0 million , respectively, were subject to a master netting agreement, compared to $26.5 million and $11.9 million , respectively, at December 31, 2015 . The remaining derivatives included in the preceding table were not subject to a master netting agreement. All 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 June 30, hedging instruments: 2016 2015 Three Months Ended Net realized gains (losses): Futures contracts $ 34,871 $ (31,446 ) Foreign currency forward contracts (13,782 ) (8,724 ) TBAs 37 (182 ) Other (792 ) (1,144 ) Total $ 20,334 $ (41,496 ) Six Months Ended Net realized gains (losses): Futures contracts $ 61,322 $ (12,120 ) Foreign currency forward contracts (18,534 ) 8,095 TBAs 334 304 Other (2,056 ) (1,099 ) Total $ 41,066 $ (4,820 )

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Letter of Credit and Revolving Credit Facilities As of June 30, 2016 , ACGL and its wholly-owned subsidiaries had a $300.0 million unsecured revolving loan and letter of credit facility and a $500.0 million secured letter of credit facility (the “Credit Agreement”). Under the terms of the Credit Agreement, Arch Reinsurance Company and Arch Reinsurance Ltd. are limited to issuing an aggregate of $100.0 million of unsecured letters of credit as part of the unsecured revolving loan. The Credit Agreement expires on June 30, 2019 . In addition, certain of ACGL’s subsidiaries had outstanding letters of credit of $242.4 million as of June 30, 2016 , which were issued on a limited basis and for limited purposes (together with the secured portion of the Credit Agreement and these letter of credit facilities, the “LOC Facilities”). ACGL and its’ subsidiaries which are party to the LOC Facilities were in compliance with all covenants contained in the LOC Facilities at June 30, 2016 . At such date, $416.9 million in letters of credit under the LOC Facilities were outstanding, which were secured by investments with a fair value of $473.9 million , and had $100.0 million of borrowings outstanding under the Credit Agreement. Under the $500.0 million secured letter of credit facility, ACGL’s subsidiaries had remaining capacity of $325.4 million (outstanding letters of credit of $174.6 million ) at June 30, 2016 . As of June 30, 2016 , Watford Re had a $100.0 million letter of credit facility expiring on May 19, 2017 and an $800.0 million secured credit facility expiring on June 4, 2018 , that provides for borrowings and the issuance of letters of credit not to exceed $400.0 million . Borrowings of revolving loans may be made by Watford Re at a variable rate based on LIBOR or an alternative base rate at the option of Watford Re. At June 30, 2016 , Watford Re had $198.0 million in outstanding letters of credit under the two facilities and $297.8 million of borrowings outstanding under the secured credit facility, backed by Watford Re’s investment portfolio. Watford Re was in compliance with all covenants contained in both of its credit facilities at June 30, 2016 . The Company does not guarantee or provide credit support for Watford Re, and the Company’s financial exposure to Watford Re is limited to its investment in Watford Re’s common and preferred shares and counterparty credit risk (mitigated by collateral) arising from the reinsurance transactions. 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 $1.35 billion at June 30, 2016 , compared to $1.11 billion at December 31, 2015 .

Share Transactions

Share Transactions	6 Months Ended
	Jun. 30, 2016
Stockholders' Equity Note [Abstract]
Share Transactions	Share Transactions Share Repurchases The board of directors of ACGL has authorized the investment in ACGL’s common shares through a share repurchase program. Since the inception of the share repurchase program, ACGL has repurchased approximately 125.2 million common shares for an aggregate purchase price of $3.68 billion . For the six months ended June 30, 2016 , ACGL repurchased 1.1 million common shares (no repurchases in the 2016 second quarter ) for an aggregate purchase price of $75.3 million . During the 2015 second quarter and six months ended June 30, 2015 ACGL repurchased 3.2 million and 5.9 million common shares, respectively, for an aggregate purchase price of $199.0 million and $361.9 million , respectively. At June 30, 2016 , $446.5 million of share repurchases were available under the program. 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. Share-Based Compensation During the 2016 second quarter , the Company granted 427,379 stock options and 456,217 restricted shares and units to certain employees and directors with weighted average grant-date fair values of $17.46 and $71.61 , respectively. During the 2015 second quarter, the Company granted 534,267 stock appreciation rights and stock options and 559,332 restricted shares and units to certain employees and directors with weighted average grant-date fair values of $16.09 and $62.51 , respectively. The stock appreciation rights and stock options were valued at the grant date using the Black-Scholes option pricing model. Such values are being amortized over the respective substantive vesting period. For awards granted to retirement-eligible employees where no service is required for the employee to retain the award, the grant date fair value is immediately recognized as compensation expense at the grant date because the employee is able to retain the award without continuing to provide service. For employees near retirement eligibility, attribution of compensation cost is over the period from the grant date to the retirement eligibility date.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	6 Months Ended
	Jun. 30, 2016
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 Six Months Ended Details About Line Item That Includes June 30, June 30, AOCI Components Reclassification 2016 2015 2016 2015 Unrealized appreciation on available-for-sale investments Net realized gains (losses) $ 31,404 $ 23,259 $ 76,091 $ 65,690 Other-than-temporary impairment losses (5,395 ) (1,126 ) (13,132 ) (8,373 ) Total before tax 26,009 22,133 62,959 57,317 Income tax (expense) benefit (3,915 ) (919 ) (8,642 ) (5,171 ) Net of tax $ 22,094 $ 21,214 $ 54,317 $ 52,146 Before Tax Amount Tax Expense (Benefit) Net of Tax Amount Three Months Ended June 30, 2016 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ 117,904 $ 15,444 $ 102,460 Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) (52 ) — (52 ) Less reclassification of net realized gains (losses) included in net income 26,009 3,915 22,094 Foreign currency translation adjustments (18,186 ) (35 ) (18,151 ) Other comprehensive income (loss) $ 73,657 $ 11,494 $ 62,163 Three Months Ended June 30, 2015 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ (96,630 ) $ (14,695 ) $ (81,935 ) Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) (13 ) — (13 ) Less reclassification of net realized gains (losses) included in net income 22,133 919 21,214 Foreign currency translation adjustments 11,697 117 11,580 Other comprehensive income (loss) $ (107,079 ) $ (15,497 ) $ (91,582 ) Six Months Ended June 30, 2016 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ 270,078 $ 34,637 $ 235,441 Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) (150 ) — (150 ) Less reclassification of net realized gains (losses) included in net income 62,959 8,642 54,317 Foreign currency translation adjustments (326 ) 512 (838 ) Other comprehensive income (loss) $ 206,643 $ 26,507 $ 180,136 Six Months Ended June 30, 2015 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ (2,243 ) $ (4,612 ) $ 2,369 Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) (1,461 ) — (1,461 ) Less reclassification of net realized gains (losses) included in net income 57,317 5,171 52,146 Foreign currency translation adjustments (11,929 ) (752 ) (11,177 ) Other comprehensive income (loss) $ (72,950 ) $ (10,535 ) $ (62,415 )

Guarantor Financial Information

Guarantor Financial Information	6 Months Ended
	Jun. 30, 2016
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Guarantor Financial Information	Guarantor Financial Information The following tables present condensed financial information for ACGL, Arch Capital Group (U.S.) Inc. (“Arch-U.S.”), a 100% owned subsidiary of ACGL, and ACGL’s other subsidiaries. June 30, 2016 Condensed Consolidating Balance Sheet ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Assets Total investments $ 126 $ 54,433 $ 16,628,029 $ (14,700 ) $ 16,667,888 Cash 7,212 15,726 493,653 — 516,591 Investments in subsidiaries 7,092,328 1,802,240 — (8,894,568 ) — Due from subsidiaries and affiliates 27 50,563 388,302 (438,892 ) — Premiums receivable — — 1,775,867 (515,260 ) 1,260,607 Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses — — 5,993,929 (3,958,959 ) 2,034,970 Contractholder receivables — — 1,600,426 — 1,600,426 Prepaid reinsurance premiums — — 1,690,278 (1,149,324 ) 540,954 Deferred acquisition costs, net — — 462,906 — 462,906 Other assets 13,911 46,982 1,417,947 (151,265 ) 1,327,575 Total assets $ 7,113,604 $ 1,969,944 $ 30,451,337 $ (15,122,968 ) $ 24,411,917 Liabilities Reserve for losses and loss adjustment expenses $ — $ — $ 13,402,389 $ (3,930,742 ) $ 9,471,647 Unearned premiums — — 3,767,683 (1,149,324 ) 2,618,359 Reinsurance balances payable — — 811,247 (515,260 ) 295,987 Contractholder payables — — 1,600,426 — 1,600,426 Collateral held for insured obligations — — 261,228 261,228 Deposit accounting liabilities — — 22,325 — 22,325 Senior notes 296,914 494,478 — — 791,392 Revolving credit agreement borrowings 100,000 — 297,830 — 397,830 Due to subsidiaries and affiliates 1 35,003 403,888 (438,892 ) — Other liabilities 12,767 48,023 1,373,538 (179,482 ) 1,254,846 Total liabilities 409,682 577,504 21,940,554 (6,213,700 ) 16,714,040 Redeemable noncontrolling interests — — 220,066 (14,700 ) 205,366 Shareholders’ Equity Total shareholders’ equity available to Arch 6,703,922 1,392,440 7,502,128 (8,894,568 ) 6,703,922 Non-redeemable noncontrolling interests — — 788,589 — 788,589 Total shareholders’ equity 6,703,922 1,392,440 8,290,717 (8,894,568 ) 7,492,511 Total liabilities, noncontrolling interests and shareholders’ equity $ 7,113,604 $ 1,969,944 $ 30,451,337 $ (15,122,968 ) $ 24,411,917 December 31, 2015 Condensed Consolidating Balance Sheet ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Assets Total investments $ 50 $ 42,210 $ 15,815,381 $ (14,700 ) $ 15,842,941 Cash 6,809 17,023 529,494 — 553,326 Investments in subsidiaries 6,609,174 1,712,757 — (8,321,931 ) — Due from subsidiaries and affiliates 23 48,811 384,469 (433,303 ) — Premiums receivable — — 1,376,310 (392,867 ) 983,443 Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses — — 5,783,452 (3,916,079 ) 1,867,373 Contractholder receivables — — 1,486,296 — 1,486,296 Prepaid reinsurance premiums — — 1,511,795 (1,084,186 ) 427,609 Deferred acquisition costs, net — — 433,477 — 433,477 Other assets 4,138 45,522 2,119,279 (586,134 ) 1,582,805 Total assets $ 6,620,194 $ 1,866,323 $ 29,439,953 $ (14,749,200 ) $ 23,177,270 Liabilities Reserve for losses and loss adjustment expenses $ — $ — $ 13,010,608 $ (3,885,358 ) $ 9,125,250 Unearned premiums — — 3,418,118 (1,084,186 ) 2,333,932 Reinsurance balances payable — — 603,586 (379,466 ) 224,120 Contractholder payables — — 1,486,296 — 1,486,296 Collateral held for insured obligations — — 248,982 — 248,982 Deposit accounting liabilities — — 463,507 (203,143 ) 260,364 Senior notes 296,874 494,432 — — 791,306 Revolving credit agreement borrowings 100,000 — 430,434 — 530,434 Due to subsidiaries and affiliates 26 35,000 398,277 (433,303 ) — Other liabilities 18,413 50,890 1,385,500 (427,111 ) 1,027,692 Total liabilities 415,313 580,322 21,445,308 (6,412,567 ) 16,028,376 Redeemable noncontrolling interests — — 219,882 (14,700 ) 205,182 Shareholders’ Equity Total shareholders’ equity available to Arch 6,204,881 1,286,001 7,035,932 (8,321,933 ) 6,204,881 Non-redeemable noncontrolling interests — — 738,831 — 738,831 Total shareholders’ equity 6,204,881 1,286,001 7,774,763 (8,321,933 ) 6,943,712 Total liabilities, noncontrolling interests and shareholders’ equity $ 6,620,194 $ 1,866,323 $ 29,439,953 $ (14,749,200 ) $ 23,177,270 Three Months Ended June 30, 2016 Condensed Consolidating Statement of Income and Comprehensive Income ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Revenues Net premiums earned $ — $ — $ 1,005,985 $ — $ 1,005,985 Net investment income — 775 94,097 (6,534 ) 88,338 Net realized gains (losses) — — 68,218 — 68,218 Net impairment losses recognized in earnings — — (5,343 ) — (5,343 ) Other underwriting income — — 41,450 (16,226 ) 25,224 Equity in net income (loss) of investment funds accounted for using the equity method — — 8,737 — 8,737 Other income (loss) (7 ) — — — (7 ) Total revenues (7 ) 775 1,213,144 (22,760 ) 1,191,152 Expenses Losses and loss adjustment expenses — — 584,592 — 584,592 Acquisition expenses — — 175,281 — 175,281 Other operating expenses — — 159,590 — 159,590 Corporate expenses 17,441 359 (600 ) — 17,200 Interest expense 5,929 6,647 25,527 (22,440 ) 15,663 Net foreign exchange (gains) losses — — (14,125 ) (10,537 ) (24,662 ) Total expenses 23,370 7,006 930,265 (32,977 ) 927,664 Income (loss) before income taxes (23,377 ) (6,231 ) 282,879 10,217 263,488 Income tax (expense) benefit — 2,086 (16,217 ) — (14,131 ) Income (loss) before equity in net income of subsidiaries (23,377 ) (4,145 ) 266,662 10,217 249,357 Equity in net income of subsidiaries 234,432 19,873 — (254,305 ) — Net income 211,055 15,728 266,662 (244,088 ) 249,357 Net (income) loss attributable to noncontrolling interests — — (38,623 ) 321 (38,302 ) Net income available to Arch 211,055 15,728 228,039 (243,767 ) 211,055 Preferred dividends (5,485 ) — — — (5,485 ) Net income available to Arch common shareholders $ 205,570 $ 15,728 $ 228,039 $ (243,767 ) $ 205,570 Comprehensive income (loss) available to Arch $ 273,260 $ 28,536 $ 300,542 $ (329,078 ) $ 273,260 Three Months Ended June 30, 2015 Condensed Consolidating Statement of Income and Comprehensive Income ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Revenues Net premiums earned $ — $ — $ 943,438 $ — $ 943,438 Net investment income — 800 87,154 (991 ) 86,963 Net realized gains (losses) — 1 (35,726 ) — (35,725 ) Net impairment losses recognized in earnings — — (1,113 ) — (1,113 ) Other underwriting income — — 7,717 — 7,717 Equity in net income (loss) of investment funds accounted for using the equity method — — 16,167 — 16,167 Other income (loss) — — 2,205 — 2,205 Total revenues — 801 1,019,842 (991 ) 1,019,652 Expenses Losses and loss adjustment expenses — — 519,426 — 519,426 Acquisition expenses — — 175,425 — 175,425 Other operating expenses — — 151,190 — 151,190 Corporate expenses 16,900 1,012 (494 ) — 17,418 Interest expense 5,862 6,769 (7,793 ) (827 ) 4,011 Net foreign exchange (gains) losses — — 6,942 12,641 19,583 Total expenses 22,762 7,781 844,696 11,814 887,053 Income (loss) before income taxes (22,762 ) (6,980 ) 175,146 (12,805 ) 132,599 Income tax (expense) benefit — 3,697 (10,477 ) — (6,780 ) Income (loss) before equity in net income of subsidiaries (22,762 ) (3,283 ) 164,669 (12,805 ) 125,819 Equity in net income of subsidiaries 138,552 14,077 — (152,629 ) — Net income 115,790 10,794 164,669 (165,434 ) 125,819 Net (income) loss attributable to noncontrolling interests — — (10,193 ) 164 (10,029 ) Net income available to Arch 115,790 10,794 154,476 (165,270 ) 115,790 Preferred dividends (5,485 ) — — — (5,485 ) Net income available to Arch common shareholders $ 110,305 $ 10,794 $ 154,476 $ (165,270 ) $ 110,305 Comprehensive income (loss) available to Arch $ 24,208 $ (13,505 ) $ 50,249 $ (36,744 ) $ 24,208 Six Months Ended June 30, 2016 Condensed Consolidating Statement of Income and Comprehensive Income ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Revenues Net premiums earned $ — $ — $ 1,957,564 $ — $ 1,957,564 Net investment income 1 1,548 194,358 (13,834 ) 182,073 Net realized gains (losses) — — 105,542 — 105,542 Net impairment losses recognized in earnings — — (12,982 ) — (12,982 ) Other underwriting income — — 46,769 (16,498 ) 30,271 Equity in net income (loss) of investment funds accounted for using the equity method — — 15,392 — 15,392 Other income (loss) 199 — (231 ) — (32 ) Total revenues 200 1,548 2,306,412 (30,332 ) 2,277,828 Expenses Losses and loss adjustment expenses — — 1,107,541 — 1,107,541 Acquisition expenses — — 345,746 — 345,746 Other operating expenses — — 311,859 — 311,859 Corporate expenses 26,796 941 (1,154 ) — 26,583 Interest expense 11,863 13,319 36,279 (29,691 ) 31,770 Net foreign exchange (gains) losses — — 2,370 (3,466 ) (1,096 ) Total expenses 38,659 14,260 1,802,641 (33,157 ) 1,822,403 Income (loss) before income taxes (38,459 ) (12,712 ) 503,771 2,825 455,425 Income tax (expense) benefit — 4,330 (34,771 ) — (30,441 ) Income (loss) before equity in net income of subsidiaries (38,459 ) (8,382 ) 469,000 2,825 424,984 Equity in net income of subsidiaries 404,312 42,739 — (447,051 ) — Net income 365,853 34,357 469,000 (444,226 ) 424,984 Net (income) loss attributable to noncontrolling interests — — (59,773 ) 642 (59,131 ) Net income available to Arch 365,853 34,357 409,227 (443,584 ) 365,853 Preferred dividends (10,969 ) — — — (10,969 ) Net income available to Arch common shareholders $ 354,884 $ 34,357 $ 409,227 $ (443,584 ) $ 354,884 Comprehensive income (loss) available to Arch $ 546,189 $ 87,185 $ 592,793 $ (679,978 ) $ 546,189 Six Months Ended June 30, 2015 Condensed Consolidating Statement of Income and Comprehensive Income ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Revenues Net premiums earned $ — $ — $ 1,853,702 $ — $ 1,853,702 Net investment income — 805 173,164 (8,012 ) 165,957 Net realized gains (losses) — 1 47,622 — 47,623 Net impairment losses recognized in earnings — — (6,912 ) — (6,912 ) Other underwriting income — — 19,253 — 19,253 Equity in net income (loss) of investment funds accounted for using the equity method — — 22,056 — 22,056 Other income (loss) — — 317 — 317 Total revenues — 806 2,109,202 (8,012 ) 2,101,996 Expenses Losses and loss adjustment expenses — — 1,013,142 — 1,013,142 Acquisition expenses — — 338,501 — 338,501 Other operating expenses — — 299,727 — 299,727 Corporate expenses 25,532 2,271 (1,040 ) — 26,763 Interest expense 11,718 13,135 (258 ) (7,848 ) 16,747 Net foreign exchange (gains) losses — — (32,688 ) (14,230 ) (46,918 ) Total expenses 37,250 15,406 1,617,384 (22,078 ) 1,647,962 Income (loss) before income taxes (37,250 ) (14,600 ) 491,818 14,066 454,034 Income tax (expense) benefit — 5,110 (24,568 ) — (19,458 ) Income (loss) before equity in net income of subsidiaries (37,250 ) (9,490 ) 467,250 14,066 434,576 Equity in net income of subsidiaries 436,376 28,572 — (464,948 ) — Net income 399,126 19,082 467,250 (450,882 ) 434,576 Net (income) loss attributable to noncontrolling interests — — (35,614 ) 164 (35,450 ) Net income available to Arch 399,126 19,082 431,636 (450,718 ) 399,126 Preferred dividends (10,969 ) — — — (10,969 ) Net income available to Arch common shareholders $ 388,157 $ 19,082 $ 431,636 $ (450,718 ) $ 388,157 Comprehensive income (loss) available to Arch $ 336,711 $ (1,755 ) $ 383,442 $ (381,687 ) $ 336,711 Six Months Ended June 30, 2016 Condensed Consolidating Statement of Cash Flows ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Operating Activities Net Cash Provided By (Used For) Operating Activities $ 89,499 $ 10,732 $ 588,067 $ (147,074 ) $ 541,224 Investing Activities Purchases of fixed maturity investments — — (17,541,731 ) — (17,541,731 ) Purchases of equity securities — — (212,678 ) — (212,678 ) Purchases of other investments — — (650,613 ) — (650,613 ) Proceeds from the sales of fixed maturity investments — — 16,978,549 — 16,978,549 Proceeds from the sales of equity securities — — 337,619 — 337,619 Proceeds from the sales, redemptions and maturities of other investments — — 636,535 — 636,535 Proceeds from redemptions and maturities of fixed maturity investments — 41,500 329,480 — 370,980 Net settlements of derivative instruments — — 45,174 — 45,174 Net (purchases) sales of short-term investments (76 ) (53,729 ) (250,655 ) — (304,460 ) Change in cash collateral related to securities lending — — (18,715 ) — (18,715 ) Contributions to subsidiaries (3,300 ) — (2,779 ) 6,079 — Intercompany loans issued — — — — — Purchase of business, net of cash acquired — — (1,460 ) — (1,460 ) Purchases of fixed assets (8 ) — (8,276 ) — (8,284 ) Change in other assets 2,000 — 11,416 — 13,416 Net Cash Provided By (Used For) Investing Activities (1,384 ) (12,229 ) (348,134 ) 6,079 (355,668 ) Financing Activities Purchases of common shares under share repurchase program (75,256 ) — — — (75,256 ) Proceeds from common shares issued, net (1,487 ) — 6,079 (6,079 ) (1,487 ) Proceeds from borrowings — — 46,000 — 46,000 Repayments of borrowings — — (179,171 ) — (179,171 ) Change in cash collateral related to securities lending — — 18,715 — 18,715 Dividends paid to redeemable noncontrolling interests — — (9,632 ) 638 (8,994 ) Dividends paid to parent (1) — — (146,436 ) 146,436 — Other — 200 (2,423 ) — (2,223 ) Preferred dividends paid (10,969 ) — — — (10,969 ) Net Cash Provided By (Used For) Financing Activities (87,712 ) 200 (266,868 ) 140,995 (213,385 ) Effects of exchange rates changes on foreign currency cash — — (8,906 ) — (8,906 ) Increase (decrease) in cash 403 (1,297 ) (35,841 ) — (36,735 ) Cash beginning of year 6,809 17,023 529,494 — 553,326 Cash end of period $ 7,212 $ 15,726 $ 493,653 $ — $ 516,591 (1) Included in net cash provided by (used for) operating activities in the ACGL (Parent Guarantor) column. Six Months Ended June 30, 2015 Condensed Consolidating Statement of Cash Flows ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Operating Activities Net Cash Provided By (Used For) Operating Activities $ 378,703 $ 8,282 $ 433,833 $ (435,619 ) $ 385,199 Investing Activities Purchases of fixed maturity investments — — (14,641,391 ) — (14,641,391 ) Purchases of equity securities — — (288,535 ) — (288,535 ) Purchases of other investments — — (779,678 ) — (779,678 ) Proceeds from the sales of fixed maturity investments — 20,002 14,313,434 — 14,333,436 Proceeds from the sales of equity securities — — 272,343 — 272,343 Proceeds from the sales, redemptions and maturities of other investments — — 587,650 — 587,650 Proceeds from redemptions and maturities of fixed maturity investments — — 474,984 — 474,984 Net settlements of derivative instruments — — 19,006 — 19,006 Proceeds from investment in joint venture — — 40,000 — 40,000 Net (purchases) sales of short-term investments (365 ) (12,171 ) 16,243 — 3,707 Change in cash collateral related to securities lending — — (18,329 ) — (18,329 ) Contributions to subsidiaries — — (9,290 ) 9,290 — Intercompany loans issued — (39,500 ) (27,500 ) 67,000 — Purchase of business, net of cash acquired — — 818 — 818 Purchases of fixed assets (24 ) — (6,372 ) — (6,396 ) Change in other assets — — (36,769 ) — (36,769 ) Net Cash Provided By (Used For) Investing Activities (389 ) (31,669 ) (83,386 ) 76,290 (39,154 ) Financing Activities Purchases of common shares under share repurchase program (361,877 ) — — — (361,877 ) Proceeds from common shares issued, net 2,178 — 9,290 (9,290 ) 2,178 Proceeds from intercompany borrowings — 27,500 39,500 (67,000 ) — Change in cash collateral related to securities lending — — 18,329 — 18,329 Dividends paid to redeemable noncontrolling interests — — (9,632 ) 319 (9,313 ) Dividends paid to parent (1) — — (435,300 ) 435,300 — Other — 28 54,990 — 55,018 Preferred dividends paid (10,969 ) — — — (10,969 ) Net Cash Provided By (Used For) Financing Activities (370,668 ) 27,528 (322,823 ) 359,329 (306,634 ) Effects of exchange rates changes on foreign currency cash — — (39 ) — (39 ) Increase (decrease) in cash 7,646 4,141 27,585 — 39,372 Cash beginning of year 3,218 2,787 479,697 — 485,702 Cash end of period $ 10,864 $ 6,928 $ 507,282 $ — $ 525,074 (1) Included in net cash provided by (used for) operating activities in the ACGL (Parent Guarantor) column.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company’s income tax provision on income before income taxes resulted in an expense of 6.7% for the six months ended June 30, 2016 , compared to an expense of 4.3% for the 2015 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. The Company had a net deferred tax asset of $113.0 million at June 30, 2016 , compared to $135.7 million at December 31, 2015 . In addition, the Company paid $26.6 million and $26.0 million of income taxes for the six months ended June 30, 2016 and 2015 , respectively.

Legal Proceedings

Legal Proceedings	6 Months Ended
	Jun. 30, 2016
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 June 30, 2016 , 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.

Transactions with Related Parti

Transactions with Related Parties	6 Months Ended
	Jun. 30, 2016
Related Party Transactions [Abstract]
Transactions with Related Parties	Transactions with Related Parties Kewsong Lee, a director of ACGL, is a Managing Director and Deputy Chief Investment Officer for Corporate Private Equity of The Carlyle Group (“Carlyle”). As part of its investment philosophy, the Company invests a portion of its investment portfolio in alternative investment funds. As of June 30, 2016 , the Company had aggregate commitments of $770.9 million to funds managed by Carlyle, of which $513.1 million was unfunded. The Company may make additional commitments to funds managed by Carlyle from time to time. During the six months ended June 30, 2016 and 2015 , the Company made aggregate capital contributions to funds managed by Carlyle of $56.6 million and $25.6 million , respectively, and received aggregate cash distributions from funds managed by Carlyle of $13.8 million and $19.8 million , respectively.

General (Policies)

General (Policies)	6 Months Ended
	Jun. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
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.
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 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.

Variable Interest Entities an24

Variable Interest Entities and Noncontrolling Interests (Tables)	6 Months Ended
	Jun. 30, 2016
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 Re are reported: June 30, December 31, 2016 2015 Assets Investments accounted for using the fair value option $ 1,677,836 $ 1,617,107 Cash 74,525 108,550 Accrued investment income 16,329 19,249 Premiums receivable 197,062 162,263 Reinsurance recoverable on unpaid and paid losses 16,675 14,135 Prepaid reinsurance premiums 10,602 11,129 Deferred acquisition costs, net 80,304 75,443 Receivable for securities sold 40,467 34,095 Other assets 92,935 80,361 Total assets of consolidated VIE $ 2,206,735 $ 2,122,332 Liabilities Reserves for losses and loss adjustment expenses $ 404,653 $ 290,997 Unearned premiums 260,721 249,980 Reinsurance balances payable 12,872 14,005 Revolving credit agreement borrowings 297,830 430,434 Payable for securities purchased 34,729 33,062 Other liabilities 89,593 53,624 Total liabilities of consolidated VIE $ 1,100,398 $ 1,072,102 Redeemable noncontrolling interests $ 220,066 $ 219,882
Activity in non-redeemable noncontrolling interests	The following table sets forth activity in the non-redeemable noncontrolling interests: June 30, 2016 2015 Three Months Ended Balance, beginning of period $ 754,915 $ 789,594 Amounts attributable to noncontrolling interests 33,716 5,286 Foreign currency translation adjustments attributable to noncontrolling interests (42 ) — Balance, end of period $ 788,589 $ 794,880 Six Months Ended Balance, beginning of year $ 738,831 $ 769,081 Amounts attributable to noncontrolling interests 49,958 25,799 Foreign currency translation adjustments attributable to noncontrolling interests (200 ) — Balance, end of period $ 788,589 $ 794,880
Activity in redeemable noncontrolling interests	The following table sets forth activity in the redeemable non-controlling interests: June 30, 2016 2015 Three Months Ended Balance, beginning of period $ 205,274 $ 219,604 Shares acquired by the Company — (14,700 ) Accretion of preference share issuance costs 92 92 Balance, end of period $ 205,366 $ 204,996 Six Months Ended Balance, beginning of year $ 205,182 $ 219,512 Shares acquired by the Company — (14,700 ) Accretion of preference share issuance costs 184 184 Balance, end of period $ 205,366 $ 204,996
Portion of income or loss attributable to third party investors	The portion of Watford Re’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: June 30, 2016 2015 Three Months Ended Amounts attributable to non-redeemable noncontrolling interests $ (33,716 ) $ (5,286 ) Dividends attributable to redeemable noncontrolling interests (4,586 ) (4,743 ) Net (income) loss attributable to noncontrolling interests $ (38,302 ) $ (10,029 ) Six Months Ended Amounts attributable to non-redeemable noncontrolling interests $ (49,958 ) $ (25,799 ) Dividends attributable to redeemable noncontrolling interests (9,173 ) (9,651 ) Net (income) loss attributable to noncontrolling interests $ (59,131 ) $ (35,450 )

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	6 Months Ended
	Jun. 30, 2016
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 Six Months Ended June 30, June 30, 2016 2015 2016 2015 Numerator: Net income $ 249,357 $ 125,819 $ 424,984 $ 434,576 Net (income) loss attributable to noncontrolling interests (38,302 ) (10,029 ) (59,131 ) (35,450 ) Net income available to Arch 211,055 115,790 365,853 399,126 Preferred dividends (5,485 ) (5,485 ) (10,969 ) (10,969 ) Net income available to Arch common shareholders $ 205,570 $ 110,305 $ 354,884 $ 388,157 Denominator: Weighted average common shares outstanding — basic 120,599,060 121,719,214 120,513,620 122,957,384 Effect of dilutive common share equivalents: Nonvested restricted shares 1,295,342 1,258,741 1,374,272 1,334,633 Stock options (1) 2,471,194 2,907,465 2,537,234 2,864,696 Weighted average common shares and common share equivalents outstanding — diluted 124,365,596 125,885,420 124,425,126 127,156,713 Earnings per common share: Basic $ 1.70 $ 0.91 $ 2.94 $ 3.16 Diluted $ 1.65 $ 0.88 $ 2.85 $ 3.05 (1) 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 2016 second quarter and 2015 second quarter , the number of stock options excluded were 575,931 and 1,009,113 , respectively. For the six months ended June 30, 2016 and 2015 , the number of stock options excluded were 1,027,784 and 1,187,162 , respectively.

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2016
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 common shareholders: Three Months Ended June 30, 2016 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 762,043 $ 412,053 $ 118,434 $ 1,292,199 $ 109,285 $ 1,329,936 Premiums ceded (246,875 ) (119,951 ) (6,969 ) (373,464 ) (4,457 ) (306,373 ) Net premiums written 515,168 292,102 111,465 918,735 104,828 1,023,563 Change in unearned premiums 12,482 (846 ) (44,953 ) (33,317 ) 15,739 (17,578 ) Net premiums earned 527,650 291,256 66,512 885,418 120,567 1,005,985 Other underwriting income — 20,118 4,137 24,255 969 25,224 Losses and loss adjustment expenses (354,633 ) (146,091 ) (366 ) (501,090 ) (83,502 ) (584,592 ) Acquisition expenses, net (77,317 ) (55,796 ) (8,523 ) (141,636 ) (33,645 ) (175,281 ) Other operating expenses (92,371 ) (37,115 ) (23,991 ) (153,477 ) (6,113 ) (159,590 ) Underwriting income (loss) $ 3,329 $ 72,372 $ 37,769 113,470 (1,724 ) 111,746 Net investment income 70,397 17,941 88,338 Net realized gains (losses) 40,927 27,291 68,218 Net impairment losses recognized in earnings (5,343 ) — (5,343 ) Equity in net income (loss) of investment funds accounted for using the equity method 8,737 — 8,737 Other income (loss) (7 ) — (7 ) Corporate expenses (17,200 ) — (17,200 ) Interest expense (12,432 ) (3,231 ) (15,663 ) Net foreign exchange gains (losses) 22,461 2,201 24,662 Income (loss) before income taxes 221,010 42,478 263,488 Income tax expense (14,131 ) — (14,131 ) Net income (loss) 206,879 42,478 249,357 Dividends attributable to redeemable noncontrolling interests — (4,586 ) (4,586 ) Amounts attributable to noncontrolling interests — (33,716 ) (33,716 ) Net income (loss) available to Arch 206,879 4,176 211,055 Preferred dividends (5,485 ) — (5,485 ) Net income (loss) available to Arch common shareholders $ 201,394 $ 4,176 $ 205,570 Underwriting Ratios Loss ratio 67.2 % 50.2 % 0.6 % 56.6 % 69.3 % 58.1 % Acquisition expense ratio 14.7 % 19.2 % 12.8 % 16.0 % 27.9 % 17.4 % Other operating expense ratio 17.5 % 12.7 % 36.1 % 17.3 % 5.1 % 15.9 % Combined ratio 99.4 % 82.1 % 49.5 % 89.9 % 102.3 % 91.4 % Goodwill and intangible assets $ 27,457 $ 1,440 $ 59,430 $ 88,327 $ — $ 88,327 (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. Three Months Ended June 30, 2015 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 744,810 $ 342,101 $ 68,572 $ 1,155,253 $ 127,954 $ 1,199,209 Premiums ceded (235,743 ) (89,446 ) (6,902 ) (331,861 ) (7,766 ) (255,629 ) Net premiums written 509,067 252,655 61,670 823,392 120,188 943,580 Change in unearned premiums 758 21,310 (9,211 ) 12,857 (12,999 ) (142 ) Net premiums earned 509,825 273,965 52,459 836,249 107,189 943,438 Other underwriting income 521 2,658 3,686 6,865 852 7,717 Losses and loss adjustment expenses (320,926 ) (111,183 ) (9,639 ) (441,748 ) (77,678 ) (519,426 ) Acquisition expenses, net (76,723 ) (58,360 ) (10,200 ) (145,283 ) (30,142 ) (175,425 ) Other operating expenses (89,054 ) (39,007 ) (19,679 ) (147,740 ) (3,450 ) (151,190 ) Underwriting income (loss) $ 23,643 $ 68,073 $ 16,627 108,343 (3,229 ) 105,114 Net investment income 67,171 19,792 86,963 Net realized gains (losses) (26,860 ) (8,865 ) (35,725 ) Net impairment losses recognized in earnings (1,113 ) — (1,113 ) Equity in net income (loss) of investment funds accounted for using the equity method 16,167 — 16,167 Other income (loss) 2,205 — 2,205 Corporate expenses (17,418 ) — (17,418 ) Interest expense (4,011 ) — (4,011 ) Net foreign exchange gains (losses) (22,571 ) 2,988 (19,583 ) Income (loss) before income taxes 121,913 10,686 132,599 Income tax expense (6,780 ) — (6,780 ) Net income (loss) 115,133 10,686 125,819 Dividends attributable to redeemable noncontrolling interests — (4,743 ) (4,743 ) Amounts attributable to noncontrolling interests — (5,286 ) (5,286 ) Net income (loss) available to Arch 115,133 657 115,790 Preferred dividends (5,485 ) — (5,485 ) Net income (loss) available to Arch common shareholders $ 109,648 $ 657 $ 110,305 Underwriting Ratios Loss ratio 62.9 % 40.6 % 18.4 % 52.8 % 72.5 % 55.1 % Acquisition expense ratio 15.0 % 21.3 % 19.4 % 17.4 % 28.1 % 18.6 % Other operating expense ratio 17.5 % 14.2 % 37.5 % 17.7 % 3.2 % 16.0 % Combined ratio 95.4 % 76.1 % 75.3 % 87.9 % 103.8 % 89.7 % Goodwill and intangible assets $ 30,968 $ 2,420 $ 69,130 $ 102,518 $ — $ 102,518 (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. Six Months Ended June 30, 2016 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 1,560,596 $ 893,443 $ 229,714 $ 2,683,260 $ 257,891 $ 2,767,902 Premiums ceded (495,664 ) (280,517 ) (11,736 ) (787,424 ) (8,929 ) (623,104 ) Net premiums written 1,064,932 612,926 217,978 1,895,836 248,962 2,144,798 Change in unearned premiums (24,193 ) (60,462 ) (89,701 ) (174,356 ) (12,878 ) (187,234 ) Net premiums earned 1,040,739 552,464 128,277 1,721,480 236,084 1,957,564 Other underwriting income — 20,443 7,930 28,373 1,898 30,271 Losses and loss adjustment expenses (678,242 ) (257,689 ) (8,995 ) (944,926 ) (162,615 ) (1,107,541 ) Acquisition expenses, net (151,671 ) (110,583 ) (16,908 ) (279,162 ) (66,584 ) (345,746 ) Other operating expenses (178,232 ) (73,570 ) (48,606 ) (300,408 ) (11,451 ) (311,859 ) Underwriting income (loss) $ 32,594 $ 131,065 $ 61,698 225,357 (2,668 ) 222,689 Net investment income 140,806 41,267 182,073 Net realized gains (losses) 72,789 32,753 105,542 Net impairment losses recognized in earnings (12,982 ) — (12,982 ) Equity in net income (loss) of investment funds accounted for using the equity method 15,392 — 15,392 Other income (loss) (32 ) — (32 ) Corporate expenses (26,583 ) — (26,583 ) Interest expense (25,059 ) (6,711 ) (31,770 ) Net foreign exchange gains (losses) 420 676 1,096 Income (loss) before income taxes 390,108 65,317 455,425 Income tax expense (30,441 ) — (30,441 ) Net income (loss) 359,667 65,317 424,984 Dividends attributable to redeemable noncontrolling interests — (9,173 ) (9,173 ) Amounts attributable to noncontrolling interests — (49,958 ) (49,958 ) Net income (loss) available to Arch 359,667 6,186 365,853 Preferred dividends (10,969 ) — (10,969 ) Net income (loss) available to Arch common shareholders $ 348,698 $ 6,186 $ 354,884 Underwriting Ratios Loss ratio 65.2 % 46.6 % 7.0 % 54.9 % 68.9 % 56.6 % Acquisition expense ratio 14.6 % 20.0 % 13.2 % 16.2 % 28.2 % 17.7 % Other operating expense ratio 17.1 % 13.3 % 37.9 % 17.5 % 4.9 % 15.9 % Combined ratio 96.9 % 79.9 % 58.1 % 88.6 % 102.0 % 90.2 % (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. Six Months Ended June 30, 2015 Insurance Reinsurance Mortgage Sub-Total Other Total Gross premiums written (1) $ 1,510,963 $ 827,213 $ 129,113 $ 2,466,931 $ 256,587 $ 2,541,231 Premiums ceded (459,893 ) (226,015 ) (15,572 ) (701,122 ) (11,821 ) (530,656 ) Net premiums written 1,051,070 601,198 113,541 1,765,809 244,766 2,010,575 Change in unearned premiums (33,331 ) (47,516 ) (10,715 ) (91,562 ) (65,311 ) (156,873 ) Net premiums earned 1,017,739 553,682 102,826 1,674,247 179,455 1,853,702 Other underwriting income 948 4,087 11,404 16,439 2,814 19,253 Losses and loss adjustment expenses (638,822 ) (223,715 ) (23,448 ) (885,985 ) (127,157 ) (1,013,142 ) Acquisition expenses, net (151,801 ) (114,964 ) (20,618 ) (287,383 ) (51,118 ) (338,501 ) Other operating expenses (177,173 ) (77,051 ) (40,048 ) (294,272 ) (5,455 ) (299,727 ) Underwriting income $ 50,891 $ 142,039 $ 30,116 223,046 (1,461 ) 221,585 Net investment income 137,459 28,498 165,957 Net realized gains 38,649 8,974 47,623 Net impairment losses recognized in earnings (6,912 ) — (6,912 ) Equity in net income (loss) of investment funds accounted for using the equity method 22,056 — 22,056 Other income (loss) 317 — 317 Corporate expenses (26,763 ) — (26,763 ) Interest expense (16,747 ) — (16,747 ) Net foreign exchange gains (losses) 44,282 2,636 46,918 Income (loss) before income taxes 415,387 38,647 454,034 Income tax expense (19,458 ) — (19,458 ) Net income (loss) 395,929 38,647 434,576 Dividends attributable to redeemable noncontrolling interests — (9,651 ) (9,651 ) Amounts attributable to noncontrolling interests — (25,799 ) (25,799 ) Net income (loss) available to Arch 395,929 3,197 399,126 Preferred dividends (10,969 ) — (10,969 ) Net income (loss) available to Arch common shareholders $ 384,960 $ 3,197 $ 388,157 Underwriting Ratios Loss ratio 62.8 % 40.4 % 22.8 % 52.9 % 70.9 % 54.7 % Acquisition expense ratio 14.9 % 20.8 % 20.1 % 17.2 % 28.5 % 18.3 % Other operating expense ratio 17.4 % 13.9 % 38.9 % 17.6 % 3.0 % 16.2 % Combined ratio 95.1 % 75.1 % 81.8 % 87.7 % 102.4 % 89.2 % (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.

Investment Information (Tables)

Investment Information (Tables)	6 Months Ended
	Jun. 30, 2016
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 investments classified as available for sale: Estimated Fair Value Gross Unrealized Gains Gross Unrealized Losses Cost or Amortized Cost OTTI Unrealized Losses (2) June 30, 2016 Fixed maturities (1): Corporate bonds $ 2,952,173 $ 68,437 $ (17,635 ) $ 2,901,371 $ (2,304 ) Mortgage backed securities 656,891 12,973 (1,177 ) 645,095 (3,443 ) Municipal bonds 1,897,128 47,135 (678 ) 1,850,671 — Commercial mortgage backed securities 624,391 13,854 (1,004 ) 611,541 — U.S. government and government agencies 2,701,042 33,940 (749 ) 2,667,851 — Non-U.S. government securities 1,172,745 46,672 (37,074 ) 1,163,147 — Asset backed securities 1,365,766 13,492 (5,413 ) 1,357,687 (69 ) Total 11,370,136 236,503 (63,730 ) 11,197,363 (5,816 ) Equity securities 501,916 87,768 (11,163 ) 425,311 — Other investments 182,957 19,550 (4,507 ) 167,914 — Short-term investments 853,531 351 (2,584 ) 855,764 — Total $ 12,908,540 $ 344,172 $ (81,984 ) $ 12,646,352 $ (5,816 ) December 31, 2015 Fixed maturities (1): Corporate bonds $ 2,725,729 $ 15,978 $ (60,508 ) $ 2,770,259 $ (3,553 ) Mortgage backed securities 754,870 9,872 (5,334 ) 750,332 (3,350 ) Municipal bonds 1,626,281 27,014 (1,534 ) 1,600,801 — Commercial mortgage backed securities 764,152 3,269 (6,978 ) 767,861 — U.S. government and government agencies 2,423,455 6,228 (9,978 ) 2,427,205 — Non-U.S. government securities 917,664 10,414 (39,122 ) 946,372 — Asset backed securities 1,620,506 3,307 (12,951 ) 1,630,150 (22 ) Total 10,832,657 76,082 (136,405 ) 10,892,980 (6,925 ) Equity securities 629,182 94,341 (17,796 ) 552,637 — Other investments 300,476 43,798 (4,665 ) 261,343 — Short-term investments 587,904 187 (3,425 ) 591,142 — Total $ 12,350,219 $ 214,408 $ (162,291 ) $ 12,298,102 $ (6,925 ) (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.” (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 June 30, 2016 , the net unrealized gain related to securities for which a non-credit OTTI was recognized in AOCI was $1.5 million , compared to a net unrealized loss of $1.4 million at December 31, 2015 .
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 June 30, 2016 Fixed maturities (1): Corporate bonds $ 197,372 $ (4,776 ) $ 127,233 $ (12,859 ) $ 324,605 $ (17,635 ) Mortgage backed securities 67,489 (760 ) 16,999 (417 ) 84,488 (1,177 ) Municipal bonds 109,185 (277 ) 21,887 (401 ) 131,072 (678 ) Commercial mortgage backed securities 29,312 (526 ) 29,192 (478 ) 58,504 (1,004 ) U.S. government and government agencies 112,776 (749 ) — — 112,776 (749 ) Non-U.S. government securities 299,048 (15,856 ) 137,035 (21,218 ) 436,083 (37,074 ) Asset backed securities 182,387 (3,147 ) 79,147 (2,266 ) 261,534 (5,413 ) Total 997,569 (26,091 ) 411,493 (37,639 ) 1,409,062 (63,730 ) Equity securities 156,789 (11,163 ) — — 156,789 (11,163 ) Other investments 37,943 (4,507 ) — — 37,943 (4,507 ) Short-term investments 33,404 (2,584 ) — — 33,404 (2,584 ) Total $ 1,225,705 $ (44,345 ) $ 411,493 $ (37,639 ) $ 1,637,198 $ (81,984 ) December 31, 2015 Fixed maturities (1): Corporate bonds $ 1,810,988 $ (37,445 ) $ 129,896 $ (23,063 ) $ 1,940,884 $ (60,508 ) Mortgage backed securities 487,018 (4,508 ) 48,991 (826 ) 536,009 (5,334 ) Municipal bonds 269,015 (1,303 ) 9,692 (231 ) 278,707 (1,534 ) Commercial mortgage backed securities 511,261 (6,639 ) 20,596 (339 ) 531,857 (6,978 ) U.S. government and government agencies 1,991,163 (9,978 ) — — 1,991,163 (9,978 ) Non-U.S. government securities 458,414 (13,494 ) 138,792 (25,628 ) 597,206 (39,122 ) Asset backed securities 1,217,163 (9,328 ) 134,841 (3,623 ) 1,352,004 (12,951 ) Total 6,745,022 (82,695 ) 482,808 (53,710 ) 7,227,830 (136,405 ) Equity securities 232,275 (17,796 ) — — 232,275 (17,796 ) Other investments 93,614 (4,665 ) — — 93,614 (4,665 ) Short-term investments 30,625 (3,425 ) — — 30,625 (3,425 ) Total $ 7,101,536 $ (108,581 ) $ 482,808 $ (53,710 ) $ 7,584,344 $ (162,291 ) (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.”
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. June 30, 2016 December 31, 2015 Maturity Estimated Fair Value Amortized Cost Estimated Amortized Cost Due in one year or less $ 247,256 $ 244,247 $ 337,898 $ 341,595 Due after one year through five years 5,077,739 5,036,912 4,644,516 4,677,230 Due after five years through 10 years 2,772,938 2,699,463 2,214,413 2,228,638 Due after 10 years 625,155 602,418 496,302 497,174 8,723,088 8,583,040 7,693,129 7,744,637 Mortgage backed securities 656,891 645,095 754,870 750,332 Commercial mortgage backed securities 624,391 611,541 764,152 767,861 Asset backed securities 1,365,766 1,357,687 1,620,506 1,630,150 Total (1) $ 11,370,136 $ 11,197,363 $ 10,832,657 $ 10,892,980 (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 June 30, 2016 U.S. government and government agencies $ 242,184 $ 21,539 $ 4,109 $ 26,168 $ 294,000 Corporate bonds 33,120 — — — 33,120 Equity securities 11,198 — — — 11,198 Total $ 286,502 $ 21,539 $ 4,109 $ 26,168 $ 338,318 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 $ 338,318 December 31, 2015 U.S. government and government agencies $ 235,728 $ — $ 82,286 $ 9,598 $ 327,612 Corporate bonds 55,086 — — — 55,086 Equity securities 6,722 4,424 — — 11,146 Total $ 297,536 $ 4,424 $ 82,286 $ 9,598 $ 393,844 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 $ 393,844
Summary of other investments, including available for sale and fair value option components	The following table summarizes the Company’s other investments, including available for sale and fair value option components: June 30, December 31, Available for sale: Asian and emerging markets $ 109,767 $ 206,861 Investment grade fixed income 33,549 31,370 Credit related funds 1,698 22,512 Other 37,943 39,733 Total available for sale 182,957 300,476 Fair value option: Term loan investments (par value: $1,115,627 and $1,197,143) 1,026,543 1,108,017 Mezzanine debt funds 117,441 121,589 Credit related funds 236,184 219,049 Investment grade fixed income 65,391 63,053 Asian and emerging markets 112,265 34,761 Other (1) 107,916 124,502 Total fair value option 1,665,740 1,670,971 Total $ 1,848,697 $ 1,971,447 (1) Includes fund investments with strategies in mortgage servicing rights, transportation, infrastructure and other.
Summary of assets and liabilities accounted for using the fair value option	The following table summarizes the Company’s assets and liabilities which are accounted for using the fair value option: June 30, December 31, Fixed maturities $ 1,047,662 $ 936,802 Other investments 1,665,740 1,670,971 Short-term investments 344,797 285,923 Equity securities 7,830 798 Investments accounted for using the fair value option $ 3,066,029 $ 2,894,494
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: June 30, December 31, Investments accounted for using the equity method (1) $ 676,893 $ 584,158 Investments accounted for using the fair value option (2) 83,931 90,969 Total $ 760,824 $ 675,127 (1) Aggregate unfunded commitments were $794.7 million at June 30, 2016 , compared to $535.4 million at December 31, 2015 . (2) Aggregate unfunded commitments were $26.6 million at June 30, 2016 , compared to $22.7 million at December 31, 2015 .
Components of net investment income	The components of net investment income were derived from the following sources: June 30, 2016 2015 Three Months Ended Fixed maturities $ 77,994 $ 71,275 Term loan investments 18,608 18,033 Equity securities (dividends) 3,663 2,578 Short-term investments 816 225 Other (1) 8,260 10,489 Gross investment income 109,341 102,600 Investment expenses (21,003 ) (15,637 ) Net investment income $ 88,338 $ 86,963 Six Months Ended Fixed maturities $ 151,667 $ 139,871 Term loan investments 38,620 32,777 Equity securities (dividends) 7,098 5,257 Short-term investments 1,312 421 Other (1) 22,003 23,236 Gross investment income 220,700 201,562 Investment expenses (38,627 ) (35,605 ) Net investment income $ 182,073 $ 165,957 (1) Includes income distributions from investment funds and other items.
Summary of net realized gains (losses), excluding other-than-temporary impairment provisions	Net realized gains (losses) were as follows, excluding other than-temporary impairment provision. June 30, 2016 2015 Three Months Ended Available for sale securities: Gross gains on investment sales $ 74,695 $ 82,233 Gross losses on investment sales (43,293 ) (58,974 ) Change in fair value of assets and liabilities accounted for using the fair value option: Fixed maturities 18,632 (5,191 ) Other investments 13,136 785 Equity securities 401 (69 ) Short-term investments (621 ) (4,375 ) Derivative instruments (1) 20,334 (41,496 ) Other (2) (15,066 ) (8,638 ) Net realized gains (losses) $ 68,218 $ (35,725 ) Six Months Ended Available for sale securities: Gross gains on investment sales $ 182,514 $ 179,824 Gross losses on investment sales (106,424 ) (114,134 ) Change in fair value of assets and liabilities accounted for using the fair value option: Fixed maturities 18,299 (8,493 ) Other investments (8,412 ) 7,072 Equity securities 437 (71 ) Short-term investments (1,043 ) 1,471 Derivative instruments (1) 41,066 (4,820 ) Other (2) (20,895 ) (13,226 ) Net realized gains (losses) $ 105,542 $ 47,623 (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: June 30, 2016 2015 Three Months Ended Fixed maturities: Mortgage backed securities $ (82 ) $ (326 ) Corporate bonds (775 ) (10 ) Non-U.S. government securities (51 ) — Asset backed securities (2,500 ) — Total (3,408 ) (336 ) Short-term investments — — Equity securities (1,935 ) (124 ) Other investments — (653 ) Net impairment losses recognized in earnings $ (5,343 ) $ (1,113 ) Six Months Ended Fixed maturities: Mortgage backed securities $ (555 ) $ (1,398 ) Corporate bonds (5,655 ) (1,986 ) Non-U.S. government securities (232 ) — Asset backed securities (2,506 ) — Total (8,948 ) (3,384 ) Short-term investments — (2,341 ) Equity securities (3,037 ) (253 ) Other investments (997 ) (934 ) Net impairment losses recognized in earnings $ (12,982 ) $ (6,912 )
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: June 30, 2016 2015 Three Months Ended Balance at start of period $ 18,291 $ 24,344 Credit loss impairments recognized on securities not previously impaired 287 281 Credit loss impairments recognized on securities previously impaired — 55 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 (3,731 ) (3,774 ) Balance at end of period $ 14,847 $ 20,906 Six Months Ended Balance at start of year $ 26,875 $ 20,196 Credit loss impairments recognized on securities not previously impaired 1,350 4,770 Credit loss impairments recognized on securities previously impaired 522 134 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 (13,900 ) (4,194 ) Balance at end of period $ 14,847 $ 20,906
Summary of restricted assets	The following table details the value of the Company’s restricted assets: June 30, December 31, Assets used for collateral or guarantees: Affiliated transactions $ 3,903,933 $ 3,810,104 Third party agreements 1,598,266 1,286,257 Deposits with U.S. regulatory authorities 477,429 391,458 Deposits with non-U.S. regulatory authorities 47,429 38,230 Total restricted assets $ 6,027,057 $ 5,526,049

Fair Value (Tables)

Fair Value (Tables)	6 Months Ended
	Jun. 30, 2016
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 June 30, 2016 : 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 $ 2,952,173 $ — $ 2,934,868 $ 17,305 Mortgage backed securities 656,891 — 656,891 — Municipal bonds 1,897,128 — 1,897,128 — Commercial mortgage backed securities 624,391 — 624,391 — U.S. government and government agencies 2,701,042 2,558,706 142,336 — Non-U.S. government securities 1,172,745 — 1,172,745 — Asset backed securities 1,365,766 — 1,316,555 49,211 Total 11,370,136 2,558,706 8,744,914 66,516 Equity securities 501,916 500,158 1,758 — Short-term investments 853,531 837,202 16,329 — Other investments 79,174 79,174 — — Other investments measured at net asset value (2) 103,783 Total other investments 182,957 79,174 — — Derivative instruments (4) 30,625 — 30,625 — Fair value option: Corporate bonds 754,034 — 754,034 — Non-U.S. government bonds 101,492 — 101,492 — Mortgage backed securities 17,560 — 17,560 — Asset backed securities 22,850 — 22,850 — U.S. government and government agencies 151,726 151,726 — — Short-term investments 344,797 344,797 — — Equity securities 7,830 7,090 740 — Other investments 1,082,309 55,766 1,026,543 — Other investments measured at net asset value (2) 583,431 Total 3,066,029 559,379 1,923,219 — Total assets measured at fair value $ 16,005,194 $ 4,534,619 $ 10,716,845 $ 66,516 Liabilities measured at fair value: Contingent consideration liabilities $ (111,670 ) $ — $ — $ (111,670 ) Securities sold but not yet purchased (3) (54,668 ) — (54,668 ) — Derivative instruments (4) (26,428 ) — (26,428 ) — Total liabilities measured at fair value $ (192,766 ) $ — $ (81,096 ) $ (111,670 ) (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 , “Investment Information—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 , “Derivative Instruments.” The following table presents the Company’s financial assets and liabilities measured at fair value by level at December 31, 2015 : 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 $ 2,725,729 $ — $ 2,709,361 $ 16,368 Mortgage backed securities 754,870 — 754,870 — Municipal bonds 1,626,281 — 1,626,281 — Commercial mortgage backed securities 764,152 — 764,152 — U.S. government and government agencies 2,423,455 2,378,662 44,793 — Non-U.S. government securities 917,664 — 917,664 — Asset backed securities 1,620,506 — 1,563,006 57,500 Total 10,832,657 2,378,662 8,380,127 73,868 Equity securities 629,182 627,441 1,741 — Short-term investments 587,904 572,604 15,300 — Other investments 99,159 99,159 — — Other investments measured at net asset value (2) 201,317 Total other investments 300,476 99,159 — — Derivative instruments (4) 20,022 — 20,022 — Fair value option: Corporate bonds 771,733 — 771,733 — Non-U.S. government bonds 81,824 — 81,824 — Mortgage backed securities 57,687 — 57,687 — Asset backed securities 25,444 — 25,444 — U.S. government and government agencies 114 114 — — Short-term investments 285,923 285,923 — — Equity securities 798 798 — — Other investments 1,176,312 68,295 1,108,017 — Other investments measured at net asset value (2) 494,659 Total 2,894,494 355,130 2,044,705 — Total assets measured at fair value $ 15,264,735 $ 4,032,996 $ 10,461,895 $ 73,868 Liabilities measured at fair value: Contingent consideration liabilities $ (96,048 ) $ — $ — $ (96,048 ) Securities sold but not yet purchased (3) (30,583 ) — (30,583 ) — Derivative instruments (4) (11,863 ) — (11,863 ) — Total liabilities measured at fair value $ (138,494 ) $ — $ (42,446 ) $ (96,048 ) (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 , “Investment Information—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 , “Derivative Instruments.”
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 Asset Backed Securities Corporate Bonds Total Contingent Consideration Liabilities Three Months Ended June 30, 2016 Balance at beginning of period $ 57,500 $ 15,166 $ 72,666 $ (100,710 ) Total gains or (losses) (realized/unrealized) Included in earnings (1) (2,500 ) 1,363 (1,137 ) (10,923 ) Included in other comprehensive income — — — (37 ) Purchases, issuances, sales and settlements Purchases — 776 776 — Issuances — — — — Sales — — — — Settlements (5,789 ) — (5,789 ) — Transfers in and/or out of Level 3 — — — — Balance at end of period $ 49,211 $ 17,305 $ 66,516 $ (111,670 ) Three Months Ended June 30, 2015 Balance at beginning of period $ 57,500 $ — $ 57,500 $ (66,461 ) Total gains or (losses) (realized/unrealized) Included in earnings (1) — — — (4,795 ) Included in other comprehensive income — — — — Purchases, issuances, sales and settlements Purchases — — — — Issuances — — — — Sales — — — — Settlements — — — — Transfers in and/or out of Level 3 — — — — Balance at end of period $ 57,500 $ — $ 57,500 $ (71,256 ) Six Months Ended June 30, 2016 Balance at beginning of year $ 57,500 $ 16,368 $ 73,868 $ (96,048 ) Total gains or (losses) (realized/unrealized) Included in earnings (1) (2,500 ) 161 (2,339 ) (16,121 ) Included in other comprehensive income — — — (37 ) Purchases, issuances, sales and settlements Purchases — 776 776 — Issuances — — — — Sales — — — — Settlements (5,789 ) — (5,789 ) 536 Transfers in and/or out of Level 3 — — — — Balance at end of period $ 49,211 $ 17,305 $ 66,516 $ (111,670 ) Six Months Ended June 30, 2015 Balance at beginning of year $ 57,500 $ — $ 57,500 $ (61,845 ) Total gains or (losses) (realized/unrealized) Included in earnings (1) — — — (8,343 ) Included in other comprehensive income — — — — Purchases, issuances, sales and settlements Purchases — — — — Issuances — — — (1,068 ) Sales — — — — Settlements — — — — Transfers in and/or out of Level 3 — — — — Balance at end of period $ 57,500 $ — $ 57,500 $ (71,256 ) (1) Gains or losses on asset backed securities were included in net impairment losses recognized in earnings while gains or losses on corporate bonds and contingent consideration liabilities were included in net realized gains (losses).

Derivative Instruments (Tables)

Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 2016
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 Liability Derivatives Notional Value (1) June 30, 2016 Futures contracts (2) $ 1,208 $ (1,673 ) $ 2,287,791 Foreign currency forward contracts (2) 17,032 (18,718 ) 1,436,006 TBAs (3) 121,760 (117,673 ) 226,299 Other (2) 12,385 (6,037 ) 1,938,497 Total $ 152,385 $ (144,101 ) December 31, 2015 Futures contracts (2) $ 2,816 $ (1,202 ) $ 1,797,115 Foreign currency forward contracts (2) 9,336 (6,344 ) 773,619 TBAs (3) 6,525 — 6,316 Other (2) 7,870 (4,317 ) 1,694,935 Total $ 26,547 $ (11,863 ) (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	All 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 June 30, hedging instruments: 2016 2015 Three Months Ended Net realized gains (losses): Futures contracts $ 34,871 $ (31,446 ) Foreign currency forward contracts (13,782 ) (8,724 ) TBAs 37 (182 ) Other (792 ) (1,144 ) Total $ 20,334 $ (41,496 ) Six Months Ended Net realized gains (losses): Futures contracts $ 61,322 $ (12,120 ) Foreign currency forward contracts (18,534 ) 8,095 TBAs 334 304 Other (2,056 ) (1,099 ) Total $ 41,066 $ (4,820 )

Other Comprehensive Income (L30

Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2016
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 Six Months Ended Details About Line Item That Includes June 30, June 30, AOCI Components Reclassification 2016 2015 2016 2015 Unrealized appreciation on available-for-sale investments Net realized gains (losses) $ 31,404 $ 23,259 $ 76,091 $ 65,690 Other-than-temporary impairment losses (5,395 ) (1,126 ) (13,132 ) (8,373 ) Total before tax 26,009 22,133 62,959 57,317 Income tax (expense) benefit (3,915 ) (919 ) (8,642 ) (5,171 ) Net of tax $ 22,094 $ 21,214 $ 54,317 $ 52,146
Schedule of comprehensive income (loss)	Before Tax Amount Tax Expense (Benefit) Net of Tax Amount Three Months Ended June 30, 2016 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ 117,904 $ 15,444 $ 102,460 Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) (52 ) — (52 ) Less reclassification of net realized gains (losses) included in net income 26,009 3,915 22,094 Foreign currency translation adjustments (18,186 ) (35 ) (18,151 ) Other comprehensive income (loss) $ 73,657 $ 11,494 $ 62,163 Three Months Ended June 30, 2015 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ (96,630 ) $ (14,695 ) $ (81,935 ) Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) (13 ) — (13 ) Less reclassification of net realized gains (losses) included in net income 22,133 919 21,214 Foreign currency translation adjustments 11,697 117 11,580 Other comprehensive income (loss) $ (107,079 ) $ (15,497 ) $ (91,582 ) Six Months Ended June 30, 2016 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ 270,078 $ 34,637 $ 235,441 Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) (150 ) — (150 ) Less reclassification of net realized gains (losses) included in net income 62,959 8,642 54,317 Foreign currency translation adjustments (326 ) 512 (838 ) Other comprehensive income (loss) $ 206,643 $ 26,507 $ 180,136 Six Months Ended June 30, 2015 Unrealized appreciation (decline) in value of investments: Unrealized holding gains (losses) arising during period $ (2,243 ) $ (4,612 ) $ 2,369 Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss) (1,461 ) — (1,461 ) Less reclassification of net realized gains (losses) included in net income 57,317 5,171 52,146 Foreign currency translation adjustments (11,929 ) (752 ) (11,177 ) Other comprehensive income (loss) $ (72,950 ) $ (10,535 ) $ (62,415 )

Guarantor Financial Informati31

Guarantor Financial Information (Tables)	6 Months Ended
	Jun. 30, 2016
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed consolidating balance sheet	June 30, 2016 Condensed Consolidating Balance Sheet ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Assets Total investments $ 126 $ 54,433 $ 16,628,029 $ (14,700 ) $ 16,667,888 Cash 7,212 15,726 493,653 — 516,591 Investments in subsidiaries 7,092,328 1,802,240 — (8,894,568 ) — Due from subsidiaries and affiliates 27 50,563 388,302 (438,892 ) — Premiums receivable — — 1,775,867 (515,260 ) 1,260,607 Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses — — 5,993,929 (3,958,959 ) 2,034,970 Contractholder receivables — — 1,600,426 — 1,600,426 Prepaid reinsurance premiums — — 1,690,278 (1,149,324 ) 540,954 Deferred acquisition costs, net — — 462,906 — 462,906 Other assets 13,911 46,982 1,417,947 (151,265 ) 1,327,575 Total assets $ 7,113,604 $ 1,969,944 $ 30,451,337 $ (15,122,968 ) $ 24,411,917 Liabilities Reserve for losses and loss adjustment expenses $ — $ — $ 13,402,389 $ (3,930,742 ) $ 9,471,647 Unearned premiums — — 3,767,683 (1,149,324 ) 2,618,359 Reinsurance balances payable — — 811,247 (515,260 ) 295,987 Contractholder payables — — 1,600,426 — 1,600,426 Collateral held for insured obligations — — 261,228 261,228 Deposit accounting liabilities — — 22,325 — 22,325 Senior notes 296,914 494,478 — — 791,392 Revolving credit agreement borrowings 100,000 — 297,830 — 397,830 Due to subsidiaries and affiliates 1 35,003 403,888 (438,892 ) — Other liabilities 12,767 48,023 1,373,538 (179,482 ) 1,254,846 Total liabilities 409,682 577,504 21,940,554 (6,213,700 ) 16,714,040 Redeemable noncontrolling interests — — 220,066 (14,700 ) 205,366 Shareholders’ Equity Total shareholders’ equity available to Arch 6,703,922 1,392,440 7,502,128 (8,894,568 ) 6,703,922 Non-redeemable noncontrolling interests — — 788,589 — 788,589 Total shareholders’ equity 6,703,922 1,392,440 8,290,717 (8,894,568 ) 7,492,511 Total liabilities, noncontrolling interests and shareholders’ equity $ 7,113,604 $ 1,969,944 $ 30,451,337 $ (15,122,968 ) $ 24,411,917 December 31, 2015 Condensed Consolidating Balance Sheet ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Assets Total investments $ 50 $ 42,210 $ 15,815,381 $ (14,700 ) $ 15,842,941 Cash 6,809 17,023 529,494 — 553,326 Investments in subsidiaries 6,609,174 1,712,757 — (8,321,931 ) — Due from subsidiaries and affiliates 23 48,811 384,469 (433,303 ) — Premiums receivable — — 1,376,310 (392,867 ) 983,443 Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses — — 5,783,452 (3,916,079 ) 1,867,373 Contractholder receivables — — 1,486,296 — 1,486,296 Prepaid reinsurance premiums — — 1,511,795 (1,084,186 ) 427,609 Deferred acquisition costs, net — — 433,477 — 433,477 Other assets 4,138 45,522 2,119,279 (586,134 ) 1,582,805 Total assets $ 6,620,194 $ 1,866,323 $ 29,439,953 $ (14,749,200 ) $ 23,177,270 Liabilities Reserve for losses and loss adjustment expenses $ — $ — $ 13,010,608 $ (3,885,358 ) $ 9,125,250 Unearned premiums — — 3,418,118 (1,084,186 ) 2,333,932 Reinsurance balances payable — — 603,586 (379,466 ) 224,120 Contractholder payables — — 1,486,296 — 1,486,296 Collateral held for insured obligations — — 248,982 — 248,982 Deposit accounting liabilities — — 463,507 (203,143 ) 260,364 Senior notes 296,874 494,432 — — 791,306 Revolving credit agreement borrowings 100,000 — 430,434 — 530,434 Due to subsidiaries and affiliates 26 35,000 398,277 (433,303 ) — Other liabilities 18,413 50,890 1,385,500 (427,111 ) 1,027,692 Total liabilities 415,313 580,322 21,445,308 (6,412,567 ) 16,028,376 Redeemable noncontrolling interests — — 219,882 (14,700 ) 205,182 Shareholders’ Equity Total shareholders’ equity available to Arch 6,204,881 1,286,001 7,035,932 (8,321,933 ) 6,204,881 Non-redeemable noncontrolling interests — — 738,831 — 738,831 Total shareholders’ equity 6,204,881 1,286,001 7,774,763 (8,321,933 ) 6,943,712 Total liabilities, noncontrolling interests and shareholders’ equity $ 6,620,194 $ 1,866,323 $ 29,439,953 $ (14,749,200 ) $ 23,177,270
Condensed consolidating statement of income and comprehensive income	Three Months Ended June 30, 2016 Condensed Consolidating Statement of Income and Comprehensive Income ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Revenues Net premiums earned $ — $ — $ 1,005,985 $ — $ 1,005,985 Net investment income — 775 94,097 (6,534 ) 88,338 Net realized gains (losses) — — 68,218 — 68,218 Net impairment losses recognized in earnings — — (5,343 ) — (5,343 ) Other underwriting income — — 41,450 (16,226 ) 25,224 Equity in net income (loss) of investment funds accounted for using the equity method — — 8,737 — 8,737 Other income (loss) (7 ) — — — (7 ) Total revenues (7 ) 775 1,213,144 (22,760 ) 1,191,152 Expenses Losses and loss adjustment expenses — — 584,592 — 584,592 Acquisition expenses — — 175,281 — 175,281 Other operating expenses — — 159,590 — 159,590 Corporate expenses 17,441 359 (600 ) — 17,200 Interest expense 5,929 6,647 25,527 (22,440 ) 15,663 Net foreign exchange (gains) losses — — (14,125 ) (10,537 ) (24,662 ) Total expenses 23,370 7,006 930,265 (32,977 ) 927,664 Income (loss) before income taxes (23,377 ) (6,231 ) 282,879 10,217 263,488 Income tax (expense) benefit — 2,086 (16,217 ) — (14,131 ) Income (loss) before equity in net income of subsidiaries (23,377 ) (4,145 ) 266,662 10,217 249,357 Equity in net income of subsidiaries 234,432 19,873 — (254,305 ) — Net income 211,055 15,728 266,662 (244,088 ) 249,357 Net (income) loss attributable to noncontrolling interests — — (38,623 ) 321 (38,302 ) Net income available to Arch 211,055 15,728 228,039 (243,767 ) 211,055 Preferred dividends (5,485 ) — — — (5,485 ) Net income available to Arch common shareholders $ 205,570 $ 15,728 $ 228,039 $ (243,767 ) $ 205,570 Comprehensive income (loss) available to Arch $ 273,260 $ 28,536 $ 300,542 $ (329,078 ) $ 273,260 Three Months Ended June 30, 2015 Condensed Consolidating Statement of Income and Comprehensive Income ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Revenues Net premiums earned $ — $ — $ 943,438 $ — $ 943,438 Net investment income — 800 87,154 (991 ) 86,963 Net realized gains (losses) — 1 (35,726 ) — (35,725 ) Net impairment losses recognized in earnings — — (1,113 ) — (1,113 ) Other underwriting income — — 7,717 — 7,717 Equity in net income (loss) of investment funds accounted for using the equity method — — 16,167 — 16,167 Other income (loss) — — 2,205 — 2,205 Total revenues — 801 1,019,842 (991 ) 1,019,652 Expenses Losses and loss adjustment expenses — — 519,426 — 519,426 Acquisition expenses — — 175,425 — 175,425 Other operating expenses — — 151,190 — 151,190 Corporate expenses 16,900 1,012 (494 ) — 17,418 Interest expense 5,862 6,769 (7,793 ) (827 ) 4,011 Net foreign exchange (gains) losses — — 6,942 12,641 19,583 Total expenses 22,762 7,781 844,696 11,814 887,053 Income (loss) before income taxes (22,762 ) (6,980 ) 175,146 (12,805 ) 132,599 Income tax (expense) benefit — 3,697 (10,477 ) — (6,780 ) Income (loss) before equity in net income of subsidiaries (22,762 ) (3,283 ) 164,669 (12,805 ) 125,819 Equity in net income of subsidiaries 138,552 14,077 — (152,629 ) — Net income 115,790 10,794 164,669 (165,434 ) 125,819 Net (income) loss attributable to noncontrolling interests — — (10,193 ) 164 (10,029 ) Net income available to Arch 115,790 10,794 154,476 (165,270 ) 115,790 Preferred dividends (5,485 ) — — — (5,485 ) Net income available to Arch common shareholders $ 110,305 $ 10,794 $ 154,476 $ (165,270 ) $ 110,305 Comprehensive income (loss) available to Arch $ 24,208 $ (13,505 ) $ 50,249 $ (36,744 ) $ 24,208 Six Months Ended June 30, 2016 Condensed Consolidating Statement of Income and Comprehensive Income ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Revenues Net premiums earned $ — $ — $ 1,957,564 $ — $ 1,957,564 Net investment income 1 1,548 194,358 (13,834 ) 182,073 Net realized gains (losses) — — 105,542 — 105,542 Net impairment losses recognized in earnings — — (12,982 ) — (12,982 ) Other underwriting income — — 46,769 (16,498 ) 30,271 Equity in net income (loss) of investment funds accounted for using the equity method — — 15,392 — 15,392 Other income (loss) 199 — (231 ) — (32 ) Total revenues 200 1,548 2,306,412 (30,332 ) 2,277,828 Expenses Losses and loss adjustment expenses — — 1,107,541 — 1,107,541 Acquisition expenses — — 345,746 — 345,746 Other operating expenses — — 311,859 — 311,859 Corporate expenses 26,796 941 (1,154 ) — 26,583 Interest expense 11,863 13,319 36,279 (29,691 ) 31,770 Net foreign exchange (gains) losses — — 2,370 (3,466 ) (1,096 ) Total expenses 38,659 14,260 1,802,641 (33,157 ) 1,822,403 Income (loss) before income taxes (38,459 ) (12,712 ) 503,771 2,825 455,425 Income tax (expense) benefit — 4,330 (34,771 ) — (30,441 ) Income (loss) before equity in net income of subsidiaries (38,459 ) (8,382 ) 469,000 2,825 424,984 Equity in net income of subsidiaries 404,312 42,739 — (447,051 ) — Net income 365,853 34,357 469,000 (444,226 ) 424,984 Net (income) loss attributable to noncontrolling interests — — (59,773 ) 642 (59,131 ) Net income available to Arch 365,853 34,357 409,227 (443,584 ) 365,853 Preferred dividends (10,969 ) — — — (10,969 ) Net income available to Arch common shareholders $ 354,884 $ 34,357 $ 409,227 $ (443,584 ) $ 354,884 Comprehensive income (loss) available to Arch $ 546,189 $ 87,185 $ 592,793 $ (679,978 ) $ 546,189 Six Months Ended June 30, 2015 Condensed Consolidating Statement of Income and Comprehensive Income ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Revenues Net premiums earned $ — $ — $ 1,853,702 $ — $ 1,853,702 Net investment income — 805 173,164 (8,012 ) 165,957 Net realized gains (losses) — 1 47,622 — 47,623 Net impairment losses recognized in earnings — — (6,912 ) — (6,912 ) Other underwriting income — — 19,253 — 19,253 Equity in net income (loss) of investment funds accounted for using the equity method — — 22,056 — 22,056 Other income (loss) — — 317 — 317 Total revenues — 806 2,109,202 (8,012 ) 2,101,996 Expenses Losses and loss adjustment expenses — — 1,013,142 — 1,013,142 Acquisition expenses — — 338,501 — 338,501 Other operating expenses — — 299,727 — 299,727 Corporate expenses 25,532 2,271 (1,040 ) — 26,763 Interest expense 11,718 13,135 (258 ) (7,848 ) 16,747 Net foreign exchange (gains) losses — — (32,688 ) (14,230 ) (46,918 ) Total expenses 37,250 15,406 1,617,384 (22,078 ) 1,647,962 Income (loss) before income taxes (37,250 ) (14,600 ) 491,818 14,066 454,034 Income tax (expense) benefit — 5,110 (24,568 ) — (19,458 ) Income (loss) before equity in net income of subsidiaries (37,250 ) (9,490 ) 467,250 14,066 434,576 Equity in net income of subsidiaries 436,376 28,572 — (464,948 ) — Net income 399,126 19,082 467,250 (450,882 ) 434,576 Net (income) loss attributable to noncontrolling interests — — (35,614 ) 164 (35,450 ) Net income available to Arch 399,126 19,082 431,636 (450,718 ) 399,126 Preferred dividends (10,969 ) — — — (10,969 ) Net income available to Arch common shareholders $ 388,157 $ 19,082 $ 431,636 $ (450,718 ) $ 388,157 Comprehensive income (loss) available to Arch $ 336,711 $ (1,755 ) $ 383,442 $ (381,687 ) $ 336,711
Condensed consolidating statement of cash flows	Six Months Ended June 30, 2016 Condensed Consolidating Statement of Cash Flows ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Operating Activities Net Cash Provided By (Used For) Operating Activities $ 89,499 $ 10,732 $ 588,067 $ (147,074 ) $ 541,224 Investing Activities Purchases of fixed maturity investments — — (17,541,731 ) — (17,541,731 ) Purchases of equity securities — — (212,678 ) — (212,678 ) Purchases of other investments — — (650,613 ) — (650,613 ) Proceeds from the sales of fixed maturity investments — — 16,978,549 — 16,978,549 Proceeds from the sales of equity securities — — 337,619 — 337,619 Proceeds from the sales, redemptions and maturities of other investments — — 636,535 — 636,535 Proceeds from redemptions and maturities of fixed maturity investments — 41,500 329,480 — 370,980 Net settlements of derivative instruments — — 45,174 — 45,174 Net (purchases) sales of short-term investments (76 ) (53,729 ) (250,655 ) — (304,460 ) Change in cash collateral related to securities lending — — (18,715 ) — (18,715 ) Contributions to subsidiaries (3,300 ) — (2,779 ) 6,079 — Intercompany loans issued — — — — — Purchase of business, net of cash acquired — — (1,460 ) — (1,460 ) Purchases of fixed assets (8 ) — (8,276 ) — (8,284 ) Change in other assets 2,000 — 11,416 — 13,416 Net Cash Provided By (Used For) Investing Activities (1,384 ) (12,229 ) (348,134 ) 6,079 (355,668 ) Financing Activities Purchases of common shares under share repurchase program (75,256 ) — — — (75,256 ) Proceeds from common shares issued, net (1,487 ) — 6,079 (6,079 ) (1,487 ) Proceeds from borrowings — — 46,000 — 46,000 Repayments of borrowings — — (179,171 ) — (179,171 ) Change in cash collateral related to securities lending — — 18,715 — 18,715 Dividends paid to redeemable noncontrolling interests — — (9,632 ) 638 (8,994 ) Dividends paid to parent (1) — — (146,436 ) 146,436 — Other — 200 (2,423 ) — (2,223 ) Preferred dividends paid (10,969 ) — — — (10,969 ) Net Cash Provided By (Used For) Financing Activities (87,712 ) 200 (266,868 ) 140,995 (213,385 ) Effects of exchange rates changes on foreign currency cash — — (8,906 ) — (8,906 ) Increase (decrease) in cash 403 (1,297 ) (35,841 ) — (36,735 ) Cash beginning of year 6,809 17,023 529,494 — 553,326 Cash end of period $ 7,212 $ 15,726 $ 493,653 $ — $ 516,591 (1) Included in net cash provided by (used for) operating activities in the ACGL (Parent Guarantor) column. Six Months Ended June 30, 2015 Condensed Consolidating Statement of Cash Flows ACGL (Parent Guarantor) Arch-U.S. (Subsidiary Issuer) Other ACGL Subsidiaries Consolidating Adjustments and Eliminations ACGL Consolidated Operating Activities Net Cash Provided By (Used For) Operating Activities $ 378,703 $ 8,282 $ 433,833 $ (435,619 ) $ 385,199 Investing Activities Purchases of fixed maturity investments — — (14,641,391 ) — (14,641,391 ) Purchases of equity securities — — (288,535 ) — (288,535 ) Purchases of other investments — — (779,678 ) — (779,678 ) Proceeds from the sales of fixed maturity investments — 20,002 14,313,434 — 14,333,436 Proceeds from the sales of equity securities — — 272,343 — 272,343 Proceeds from the sales, redemptions and maturities of other investments — — 587,650 — 587,650 Proceeds from redemptions and maturities of fixed maturity investments — — 474,984 — 474,984 Net settlements of derivative instruments — — 19,006 — 19,006 Proceeds from investment in joint venture — — 40,000 — 40,000 Net (purchases) sales of short-term investments (365 ) (12,171 ) 16,243 — 3,707 Change in cash collateral related to securities lending — — (18,329 ) — (18,329 ) Contributions to subsidiaries — — (9,290 ) 9,290 — Intercompany loans issued — (39,500 ) (27,500 ) 67,000 — Purchase of business, net of cash acquired — — 818 — 818 Purchases of fixed assets (24 ) — (6,372 ) — (6,396 ) Change in other assets — — (36,769 ) — (36,769 ) Net Cash Provided By (Used For) Investing Activities (389 ) (31,669 ) (83,386 ) 76,290 (39,154 ) Financing Activities Purchases of common shares under share repurchase program (361,877 ) — — — (361,877 ) Proceeds from common shares issued, net 2,178 — 9,290 (9,290 ) 2,178 Proceeds from intercompany borrowings — 27,500 39,500 (67,000 ) — Change in cash collateral related to securities lending — — 18,329 — 18,329 Dividends paid to redeemable noncontrolling interests — — (9,632 ) 319 (9,313 ) Dividends paid to parent (1) — — (435,300 ) 435,300 — Other — 28 54,990 — 55,018 Preferred dividends paid (10,969 ) — — — (10,969 ) Net Cash Provided By (Used For) Financing Activities (370,668 ) 27,528 (322,823 ) 359,329 (306,634 ) Effects of exchange rates changes on foreign currency cash — — (39 ) — (39 ) Increase (decrease) in cash 7,646 4,141 27,585 — 39,372 Cash beginning of year 3,218 2,787 479,697 — 485,702 Cash end of period $ 10,864 $ 6,928 $ 507,282 $ — $ 525,074 (1) Included in net cash provided by (used for) operating activities in the ACGL (Parent Guarantor) column.

Variable Interest Entities an32

Variable Interest Entities and Noncontrolling Interests - Carrying amount of assets and liabilities of variable interest entity (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Investments accounted for using the fair value option	$ 3,066,029		$ 2,894,494
Cash	516,591		553,326	$ 525,074		$ 485,702
Accrued investment income	85,317		87,206
Premiums receivable	1,260,607		983,443
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	2,034,970		1,867,373
Prepaid reinsurance premiums	540,954		427,609
Deferred acquisition costs, net	462,906		433,477
Receivable for securities sold	142,315		45,505
Other assets	680,843		968,482
Total assets of consolidated VIE	24,411,917		23,177,270
Reserve for losses and loss adjustment expenses	9,471,647		9,125,250
Unearned premiums	2,618,359		2,333,932
Reinsurance balances payable	295,987		224,120
Revolving credit agreement borrowings	397,830		530,434
Payable for securities purchased	382,834		64,996
Other liabilities	533,694		568,852
Total liabilities of consolidated VIE	16,714,040		16,028,376
Redeemable noncontrolling interests	205,366		205,182
Watford Re
Variable Interest Entity [Line Items]
Redeemable noncontrolling interests	205,366	$ 205,274	205,182	$ 204,996	$ 219,604	$ 219,512
Variable Interest Entity, Primary Beneficiary | Watford Re
Variable Interest Entity [Line Items]
Investments accounted for using the fair value option	1,677,836		1,617,107
Cash	74,525		108,550
Accrued investment income	16,329		19,249
Premiums receivable	197,062		162,263
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	16,675		14,135
Prepaid reinsurance premiums	10,602		11,129
Deferred acquisition costs, net	80,304		75,443
Receivable for securities sold	40,467		34,095
Other assets	92,935		80,361
Total assets of consolidated VIE	2,206,735		2,122,332
Reserve for losses and loss adjustment expenses	404,653		290,997
Unearned premiums	260,721		249,980
Reinsurance balances payable	12,872		14,005
Revolving credit agreement borrowings	297,830		430,434
Payable for securities purchased	34,729		33,062
Other liabilities	89,593		53,624
Total liabilities of consolidated VIE	1,100,398		1,072,102
Redeemable noncontrolling interests	$ 220,066		$ 219,882

Variable Interest Entities an33

Variable Interest Entities and Noncontrolling Interests - Variable interest entity (Details) - USD ($) $ in Thousands	1 Months Ended	6 Months Ended
	Mar. 31, 2014	Jun. 30, 2016	Jun. 30, 2015
Variable Interest Entity [Line Items]
Net cash provided by operating activities		$ 541,224	$ 385,199
Net cash used for investing activities		(355,668)	(39,154)
Net cash used for financing activities		(213,385)	(306,634)
Variable Interest Entity, Primary Beneficiary | Watford Holdings Ltd
Variable Interest Entity [Line Items]
Initial investment contribution amount	$ 100,000
Ownership percentage	11.00%
Variable Interest Entity, Primary Beneficiary | Watford Re
Variable Interest Entity [Line Items]
Net cash provided by operating activities		131,000	137,800
Net cash used for investing activities		(13,800)	(134,900)
Net cash used for financing activities		$ (148,200)	$ 40,300

Variable Interest Entities an34

Variable Interest Entities and Noncontrolling Interests - Non-redeemable noncontrolling interests (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interests, beginning of period			$ 738,831
Amounts attributable to noncontrolling interests	$ 33,716	$ 5,286	49,958	$ 25,799
Non-redeemable noncontrolling interests, end of period	788,589	794,880	788,589	794,880
Watford Re
Noncontrolling Interest [Line Items]
Non-redeemable noncontrolling interests, beginning of period	754,915	789,594	738,831	769,081
Amounts attributable to noncontrolling interests	33,716	5,286	49,958	25,799
Foreign currency translation adjustments attributable to noncontrolling interests	(42)	0	(200)	0
Non-redeemable noncontrolling interests, end of period	$ 788,589	$ 794,880	$ 788,589	$ 794,880
Common shares | Watford Re
Noncontrolling Interest [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners	89.00%		89.00%

Variable Interest Entities an35

Variable Interest Entities and Noncontrolling Interests - Redeemable noncontrolling interests (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Redeemable Noncontrolling Interest [Line Items]
Redeemable noncontrolling interests, beginning of period			$ 205,182
Redeemable noncontrolling interests, end of period	$ 205,366		205,366
Watford Re
Redeemable Noncontrolling Interest [Line Items]
Redeemable noncontrolling interests, beginning of period	205,274	$ 219,604	205,182	$ 219,512
Shares acquired by the Company	0	(14,700)	0	(14,700)
Accretion of preference share issuance costs	92	92	184	184
Redeemable noncontrolling interests, end of period	$ 205,366	$ 204,996	$ 205,366	$ 204,996
Cumulative redeemable preference shares | Watford Re
Redeemable Noncontrolling Interest [Line Items]
Preference shares, number of shares issued	9,065,200		9,065,200
Par value per share	$ 0.01		$ 0.01
Liquidation preference per share	$ 25		$ 25

Variable Interest Entities an36

Variable Interest Entities and Noncontrolling Interests - Income or loss attributable to third party investors (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Noncontrolling Interest [Abstract]
Amounts attributable to non-redeemable noncontrolling interests	$ (33,716)	$ (5,286)	$ (49,958)	$ (25,799)
Dividends attributable to redeemable noncontrolling interests	(4,586)	(4,743)	(9,173)	(9,651)
Net (income) loss attributable to noncontrolling interests	$ (38,302)	$ (10,029)	$ (59,131)	$ (35,450)

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2016		Jun. 30, 2015		Jun. 30, 2016	Jun. 30, 2015
Numerator:
Net income	$ 249,357		$ 125,819		$ 424,984	$ 434,576
Net (income) loss attributable to noncontrolling interests	(38,302)		(10,029)		(59,131)	(35,450)
Net income available to Arch	211,055		115,790		365,853	399,126
Preferred dividends	(5,485)		(5,485)		(10,969)	(10,969)
Net income (loss) available to Arch common shareholders	$ 205,570		$ 110,305		$ 354,884	$ 388,157
Denominator:
Weighted average common shares outstanding — basic	120,599,060		121,719,214		120,513,620	122,957,384
Effect of dilutive common share equivalents:
Nonvested restricted shares	1,295,342		1,258,741		1,374,272	1,334,633
Stock options	2,471,194	[1]	2,907,465	[1]	2,537,234	2,864,696
Weighted average common shares and common share equivalents outstanding — diluted	124,365,596		125,885,420		124,425,126	127,156,713
Earnings per common share:
Basic (per share)	$ 1.70		$ 0.91		$ 2.94	$ 3.16
Diluted (per share)	$ 1.65		$ 0.88		$ 2.85	$ 3.05
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per common share (shares)	575,931		1,009,113		1,027,784	1,187,162
[1]	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 2016 second quarter and 2015 second quarter, the number of stock options excluded were 575,931 and 1,009,113, respectively. For the six months ended June 30, 2016 and 2015, the number of stock options excluded were 1,027,784 and 1,187,162, respectively.

Segment Information - Summary o

Segment Information - Summary of underwriting income or loss by segment (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Gross premiums written		$ 1,329,936	$ 1,199,209	$ 2,767,902	$ 2,541,231
Premiums ceded		(306,373)	(255,629)	(623,104)	(530,656)
Net premiums written		1,023,563	943,580	2,144,798	2,010,575
Change in unearned premiums		(17,578)	(142)	(187,234)	(156,873)
Net premiums earned		1,005,985	943,438	1,957,564	1,853,702
Other underwriting income		25,224	7,717	30,271	19,253
Losses and loss adjustment expenses		(584,592)	(519,426)	(1,107,541)	(1,013,142)
Acquisition expenses, net		(175,281)	(175,425)	(345,746)	(338,501)
Other operating expenses		(159,590)	(151,190)	(311,859)	(299,727)
Underwriting income (loss)		111,746	105,114	222,689	221,585
Net investment income		88,338	86,963	182,073	165,957
Net realized gains (losses)		68,218	(35,725)	105,542	47,623
Net impairment losses recognized in earnings		(5,343)	(1,113)	(12,982)	(6,912)
Equity in net income (loss) of investment funds accounted for using the equity method		8,737	16,167	15,392	22,056
Other income (loss)		(7)	2,205	(32)	317
Corporate expenses		17,200	17,418	26,583	26,763
Interest expense		(15,663)	(4,011)	(31,770)	(16,747)
Net foreign exchange gains (losses)		24,662	(19,583)	1,096	46,918
Income before income taxes		263,488	132,599	455,425	454,034
Income tax expense		(14,131)	(6,780)	(30,441)	(19,458)
Net income (loss)		249,357	125,819	424,984	434,576
Dividends attributable to redeemable noncontrolling interests		(4,586)	(4,743)	(9,173)	(9,651)
Amounts attributable to non-redeemable noncontrolling interests		(33,716)	(5,286)	(49,958)	(25,799)
Net income available to Arch		211,055	115,790	365,853	399,126
Preferred dividends		(5,485)	(5,485)	(10,969)	(10,969)
Net income (loss) available to Arch common shareholders		$ 205,570	$ 110,305	$ 354,884	$ 388,157
Underwriting Ratios
Loss ratio		58.10%	55.10%	56.60%	54.70%
Acquisition expense ratio		17.40%	18.60%	17.70%	18.30%
Other operating expense ratio		15.90%	16.00%	15.90%	16.20%
Combined ratio		91.40%	89.70%	90.20%	89.20%
Goodwill and intangible assets		$ 88,327	$ 102,518	$ 88,327	$ 102,518	$ 97,531
Other
Segment Reporting Information [Line Items]
Gross premiums written	[1]	109,285	127,954	257,891	256,587
Premiums ceded		(4,457)	(7,766)	(8,929)	(11,821)
Net premiums written		104,828	120,188	248,962	244,766
Change in unearned premiums		15,739	(12,999)	(12,878)	(65,311)
Net premiums earned		120,567	107,189	236,084	179,455
Other underwriting income		969	852	1,898	2,814
Losses and loss adjustment expenses		(83,502)	(77,678)	(162,615)	(127,157)
Acquisition expenses, net		(33,645)	(30,142)	(66,584)	(51,118)
Other operating expenses		(6,113)	(3,450)	(11,451)	(5,455)
Underwriting income (loss)		(1,724)	(3,229)	(2,668)	(1,461)
Net investment income		17,941	19,792	41,267	28,498
Net realized gains (losses)		27,291	(8,865)	32,753	8,974
Net impairment losses recognized in earnings		0	0	0	0
Equity in net income (loss) of investment funds accounted for using the equity method		0	0	0	0
Other income (loss)		0	0	0	0
Corporate expenses		0	0	0	0
Interest expense		(3,231)	0	(6,711)	0
Net foreign exchange gains (losses)		2,201	2,988	676	2,636
Income before income taxes		42,478	10,686	65,317	38,647
Income tax expense		0	0	0	0
Net income (loss)		42,478	10,686	65,317	38,647
Dividends attributable to redeemable noncontrolling interests		(4,586)	(4,743)	(9,173)	(9,651)
Amounts attributable to non-redeemable noncontrolling interests		(33,716)	(5,286)	(49,958)	(25,799)
Net income available to Arch		4,176	657	6,186	3,197
Preferred dividends		0	0	0	0
Net income (loss) available to Arch common shareholders		$ 4,176	$ 657	$ 6,186	$ 3,197
Underwriting Ratios
Loss ratio		69.30%	72.50%	68.90%	70.90%
Acquisition expense ratio		27.90%	28.10%	28.20%	28.50%
Other operating expense ratio		5.10%	3.20%	4.90%	3.00%
Combined ratio		102.30%	103.80%	102.00%	102.40%
Goodwill and intangible assets		$ 0	$ 0	$ 0	$ 0
Sub-Total
Segment Reporting Information [Line Items]
Gross premiums written	[1]	1,292,199	1,155,253	2,683,260	2,466,931
Premiums ceded		(373,464)	(331,861)	(787,424)	(701,122)
Net premiums written		918,735	823,392	1,895,836	1,765,809
Change in unearned premiums		(33,317)	12,857	(174,356)	(91,562)
Net premiums earned		885,418	836,249	1,721,480	1,674,247
Other underwriting income		24,255	6,865	28,373	16,439
Losses and loss adjustment expenses		(501,090)	(441,748)	(944,926)	(885,985)
Acquisition expenses, net		(141,636)	(145,283)	(279,162)	(287,383)
Other operating expenses		(153,477)	(147,740)	(300,408)	(294,272)
Underwriting income (loss)		113,470	108,343	225,357	223,046
Net investment income		70,397	67,171	140,806	137,459
Net realized gains (losses)		40,927	(26,860)	72,789	38,649
Net impairment losses recognized in earnings		(5,343)	(1,113)	(12,982)	(6,912)
Equity in net income (loss) of investment funds accounted for using the equity method		8,737	16,167	15,392	22,056
Other income (loss)		(7)	2,205	(32)	317
Corporate expenses		17,200	17,418	26,583	26,763
Interest expense		(12,432)	(4,011)	(25,059)	(16,747)
Net foreign exchange gains (losses)		22,461	(22,571)	420	44,282
Income before income taxes		221,010	121,913	390,108	415,387
Income tax expense		(14,131)	(6,780)	(30,441)	(19,458)
Net income (loss)		206,879	115,133	359,667	395,929
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		206,879	115,133	359,667	395,929
Preferred dividends		(5,485)	(5,485)	(10,969)	(10,969)
Net income (loss) available to Arch common shareholders		$ 201,394	$ 109,648	$ 348,698	$ 384,960
Underwriting Ratios
Loss ratio		56.60%	52.80%	54.90%	52.90%
Acquisition expense ratio		16.00%	17.40%	16.20%	17.20%
Other operating expense ratio		17.30%	17.70%	17.50%	17.60%
Combined ratio		89.90%	87.90%	88.60%	87.70%
Goodwill and intangible assets		$ 88,327	$ 102,518	$ 88,327	$ 102,518
Sub-Total | Insurance
Segment Reporting Information [Line Items]
Gross premiums written	[1]	762,043	744,810	1,560,596	1,510,963
Premiums ceded		(246,875)	(235,743)	(495,664)	(459,893)
Net premiums written		515,168	509,067	1,064,932	1,051,070
Change in unearned premiums		12,482	758	(24,193)	(33,331)
Net premiums earned		527,650	509,825	1,040,739	1,017,739
Other underwriting income		0	521	0	948
Losses and loss adjustment expenses		(354,633)	(320,926)	(678,242)	(638,822)
Acquisition expenses, net		(77,317)	(76,723)	(151,671)	(151,801)
Other operating expenses		(92,371)	(89,054)	(178,232)	(177,173)
Underwriting income (loss)		$ 3,329	$ 23,643	$ 32,594	$ 50,891
Underwriting Ratios
Loss ratio		67.20%	62.90%	65.20%	62.80%
Acquisition expense ratio		14.70%	15.00%	14.60%	14.90%
Other operating expense ratio		17.50%	17.50%	17.10%	17.40%
Combined ratio		99.40%	95.40%	96.90%	95.10%
Goodwill and intangible assets		$ 27,457	$ 30,968	$ 27,457	$ 30,968
Sub-Total | Reinsurance
Segment Reporting Information [Line Items]
Gross premiums written	[1]	412,053	342,101	893,443	827,213
Premiums ceded		(119,951)	(89,446)	(280,517)	(226,015)
Net premiums written		292,102	252,655	612,926	601,198
Change in unearned premiums		(846)	21,310	(60,462)	(47,516)
Net premiums earned		291,256	273,965	552,464	553,682
Other underwriting income		20,118	2,658	20,443	4,087
Losses and loss adjustment expenses		(146,091)	(111,183)	(257,689)	(223,715)
Acquisition expenses, net		(55,796)	(58,360)	(110,583)	(114,964)
Other operating expenses		(37,115)	(39,007)	(73,570)	(77,051)
Underwriting income (loss)		$ 72,372	$ 68,073	$ 131,065	$ 142,039
Underwriting Ratios
Loss ratio		50.20%	40.60%	46.60%	40.40%
Acquisition expense ratio		19.20%	21.30%	20.00%	20.80%
Other operating expense ratio		12.70%	14.20%	13.30%	13.90%
Combined ratio		82.10%	76.10%	79.90%	75.10%
Goodwill and intangible assets		$ 1,440	$ 2,420	$ 1,440	$ 2,420
Sub-Total | Mortgage
Segment Reporting Information [Line Items]
Gross premiums written	[1]	118,434	68,572	229,714	129,113
Premiums ceded		(6,969)	(6,902)	(11,736)	(15,572)
Net premiums written		111,465	61,670	217,978	113,541
Change in unearned premiums		(44,953)	(9,211)	(89,701)	(10,715)
Net premiums earned		66,512	52,459	128,277	102,826
Other underwriting income		4,137	3,686	7,930	11,404
Losses and loss adjustment expenses		(366)	(9,639)	(8,995)	(23,448)
Acquisition expenses, net		(8,523)	(10,200)	(16,908)	(20,618)
Other operating expenses		(23,991)	(19,679)	(48,606)	(40,048)
Underwriting income (loss)		$ 37,769	$ 16,627	$ 61,698	$ 30,116
Underwriting Ratios
Loss ratio		0.60%	18.40%	7.00%	22.80%
Acquisition expense ratio		12.80%	19.40%	13.20%	20.10%
Other operating expense ratio		36.10%	37.50%	37.90%	38.90%
Combined ratio		49.50%	75.30%	58.10%	81.80%
Goodwill and intangible assets		$ 59,430	$ 69,130	$ 59,430	$ 69,130
[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.

Segment Information - Narrative

Segment Information - Narrative (Details)	6 Months Ended
	Jun. 30, 2016segment
Underwriting segments
Segment Reporting Information [Line Items]
Number of segments	3
Other operating segments
Segment Reporting Information [Line Items]
Number of segments	2

Investment Information - Summar

Investment Information - Summary of available for sale securities (Details) - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
		Jun. 30, 2016	Dec. 31, 2015
Available for sale securities:
Estimated Fair Value		$ 12,908,540	$ 12,350,219
Gross Unrealized Gains		344,172	214,408
Gross Unrealized Losses		(81,984)	(162,291)
Cost or Amortized Cost		12,646,352	12,298,102
OTTI Unrealized Losses	[1]	(5,816)	(6,925)
Fixed maturities
Available for sale securities:
Estimated Fair Value		11,370,136	10,832,657
Gross Unrealized Gains	[2]	236,503	76,082
Gross Unrealized Losses	[2]	(63,730)	(136,405)
Cost or Amortized Cost	[2]	11,197,363	10,892,980
OTTI Unrealized Losses	[1],[2]	(5,816)	(6,925)
Fixed maturities | Corporate bonds
Available for sale securities:
Estimated Fair Value		2,952,173	2,725,729
Gross Unrealized Gains	[2]	68,437	15,978
Gross Unrealized Losses	[2]	(17,635)	(60,508)
Cost or Amortized Cost	[2]	2,901,371	2,770,259
OTTI Unrealized Losses	[1],[2]	(2,304)	(3,553)
Fixed maturities | Mortgage backed securities
Available for sale securities:
Estimated Fair Value		656,891	754,870
Gross Unrealized Gains	[2]	12,973	9,872
Gross Unrealized Losses	[2]	(1,177)	(5,334)
Cost or Amortized Cost	[2]	645,095	750,332
OTTI Unrealized Losses	[1],[2]	(3,443)	(3,350)
Fixed maturities | Municipal bonds
Available for sale securities:
Estimated Fair Value		1,897,128	1,626,281
Gross Unrealized Gains	[2]	47,135	27,014
Gross Unrealized Losses	[2]	(678)	(1,534)
Cost or Amortized Cost	[2]	1,850,671	1,600,801
OTTI Unrealized Losses	[1],[2]	0	0
Fixed maturities | Commercial mortgage backed securities
Available for sale securities:
Estimated Fair Value		624,391	764,152
Gross Unrealized Gains	[2]	13,854	3,269
Gross Unrealized Losses	[2]	(1,004)	(6,978)
Cost or Amortized Cost	[2]	611,541	767,861
OTTI Unrealized Losses	[1],[2]	0	0
Fixed maturities | US government and government agencies
Available for sale securities:
Estimated Fair Value		2,701,042	2,423,455
Gross Unrealized Gains	[2]	33,940	6,228
Gross Unrealized Losses	[2]	(749)	(9,978)
Cost or Amortized Cost	[2]	2,667,851	2,427,205
OTTI Unrealized Losses	[1],[2]	0	0
Fixed maturities | Non-US government securities
Available for sale securities:
Estimated Fair Value		1,172,745	917,664
Gross Unrealized Gains	[2]	46,672	10,414
Gross Unrealized Losses	[2]	(37,074)	(39,122)
Cost or Amortized Cost	[2]	1,163,147	946,372
OTTI Unrealized Losses	[1],[2]	0	0
Fixed maturities | Asset backed securities
Available for sale securities:
Estimated Fair Value		1,365,766	1,620,506
Gross Unrealized Gains	[2]	13,492	3,307
Gross Unrealized Losses	[2]	(5,413)	(12,951)
Cost or Amortized Cost	[2]	1,357,687	1,630,150
OTTI Unrealized Losses	[1],[2]	(69)	(22)
Equity securities
Available for sale securities:
Estimated Fair Value		501,916	629,182
Gross Unrealized Gains		87,768	94,341
Gross Unrealized Losses		(11,163)	(17,796)
Cost or Amortized Cost		425,311	552,637
OTTI Unrealized Losses	[1]	0	0
Other investments
Available for sale securities:
Estimated Fair Value		182,957	300,476
Gross Unrealized Gains		19,550	43,798
Gross Unrealized Losses		(4,507)	(4,665)
Cost or Amortized Cost		167,914	261,343
OTTI Unrealized Losses	[1]	0	0
Short-term investments
Available for sale securities:
Estimated Fair Value		853,531	587,904
Gross Unrealized Gains		351	187
Gross Unrealized Losses		(2,584)	(3,425)
Cost or Amortized Cost		855,764	591,142
OTTI Unrealized Losses	[1]	$ 0	$ 0
[1]	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 June 30, 2016, the net unrealized gain related to securities for which a non-credit OTTI was recognized in AOCI was $1.5 million, compared to a net unrealized loss of $1.4 million at December 31, 2015.
[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 “—Securities Lending Agreements.”

Investment Information - Aging

Investment Information - Aging of available for sale securities in an unrealized loss position (Details) - USD ($) $ in Thousands		Jun. 30, 2016	Dec. 31, 2015
Available for sale securities:
Estimated Fair Value - Less than 12 Months		$ 1,225,705	$ 7,101,536
Gross Unrealized Losses - Less than 12 Months		(44,345)	(108,581)
Estimated Fair Value - 12 Months or More		411,493	482,808
Gross Unrealized Losses - 12 Months or More		(37,639)	(53,710)
Estimated Fair Value - Total		1,637,198	7,584,344
Gross Unrealized Losses - Total		(81,984)	(162,291)
Fixed maturities
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	997,569	6,745,022
Gross Unrealized Losses - Less than 12 Months	[1]	(26,091)	(82,695)
Estimated Fair Value - 12 Months or More	[1]	411,493	482,808
Gross Unrealized Losses - 12 Months or More	[1]	(37,639)	(53,710)
Estimated Fair Value - Total	[1]	1,409,062	7,227,830
Gross Unrealized Losses - Total	[1]	(63,730)	(136,405)
Fixed maturities | Corporate bonds
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	197,372	1,810,988
Gross Unrealized Losses - Less than 12 Months	[1]	(4,776)	(37,445)
Estimated Fair Value - 12 Months or More	[1]	127,233	129,896
Gross Unrealized Losses - 12 Months or More	[1]	(12,859)	(23,063)
Estimated Fair Value - Total	[1]	324,605	1,940,884
Gross Unrealized Losses - Total	[1]	(17,635)	(60,508)
Fixed maturities | Mortgage backed securities
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	67,489	487,018
Gross Unrealized Losses - Less than 12 Months	[1]	(760)	(4,508)
Estimated Fair Value - 12 Months or More	[1]	16,999	48,991
Gross Unrealized Losses - 12 Months or More	[1]	(417)	(826)
Estimated Fair Value - Total	[1]	84,488	536,009
Gross Unrealized Losses - Total	[1]	(1,177)	(5,334)
Fixed maturities | Municipal bonds
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	109,185	269,015
Gross Unrealized Losses - Less than 12 Months	[1]	(277)	(1,303)
Estimated Fair Value - 12 Months or More	[1]	21,887	9,692
Gross Unrealized Losses - 12 Months or More	[1]	(401)	(231)
Estimated Fair Value - Total	[1]	131,072	278,707
Gross Unrealized Losses - Total	[1]	(678)	(1,534)
Fixed maturities | Commercial mortgage backed securities
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	29,312	511,261
Gross Unrealized Losses - Less than 12 Months	[1]	(526)	(6,639)
Estimated Fair Value - 12 Months or More	[1]	29,192	20,596
Gross Unrealized Losses - 12 Months or More	[1]	(478)	(339)
Estimated Fair Value - Total	[1]	58,504	531,857
Gross Unrealized Losses - Total	[1]	(1,004)	(6,978)
Fixed maturities | US government and government agencies
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	112,776	1,991,163
Gross Unrealized Losses - Less than 12 Months	[1]	(749)	(9,978)
Estimated Fair Value - 12 Months or More	[1]	0	0
Gross Unrealized Losses - 12 Months or More	[1]	0	0
Estimated Fair Value - Total	[1]	112,776	1,991,163
Gross Unrealized Losses - Total	[1]	(749)	(9,978)
Fixed maturities | Non-US government securities
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	299,048	458,414
Gross Unrealized Losses - Less than 12 Months	[1]	(15,856)	(13,494)
Estimated Fair Value - 12 Months or More	[1]	137,035	138,792
Gross Unrealized Losses - 12 Months or More	[1]	(21,218)	(25,628)
Estimated Fair Value - Total	[1]	436,083	597,206
Gross Unrealized Losses - Total	[1]	(37,074)	(39,122)
Fixed maturities | Asset backed securities
Available for sale securities:
Estimated Fair Value - Less than 12 Months	[1]	182,387	1,217,163
Gross Unrealized Losses - Less than 12 Months	[1]	(3,147)	(9,328)
Estimated Fair Value - 12 Months or More	[1]	79,147	134,841
Gross Unrealized Losses - 12 Months or More	[1]	(2,266)	(3,623)
Estimated Fair Value - Total	[1]	261,534	1,352,004
Gross Unrealized Losses - Total	[1]	(5,413)	(12,951)
Equity securities
Available for sale securities:
Estimated Fair Value - Less than 12 Months		156,789	232,275
Gross Unrealized Losses - Less than 12 Months		(11,163)	(17,796)
Estimated Fair Value - 12 Months or More		0	0
Gross Unrealized Losses - 12 Months or More		0	0
Estimated Fair Value - Total		156,789	232,275
Gross Unrealized Losses - Total		(11,163)	(17,796)
Other investments
Available for sale securities:
Estimated Fair Value - Less than 12 Months		37,943	93,614
Gross Unrealized Losses - Less than 12 Months		(4,507)	(4,665)
Estimated Fair Value - 12 Months or More		0	0
Gross Unrealized Losses - 12 Months or More		0	0
Estimated Fair Value - Total		37,943	93,614
Gross Unrealized Losses - Total		(4,507)	(4,665)
Short-term investments
Available for sale securities:
Estimated Fair Value - Less than 12 Months		33,404	30,625
Gross Unrealized Losses - Less than 12 Months		(2,584)	(3,425)
Estimated Fair Value - 12 Months or More		0	0
Gross Unrealized Losses - 12 Months or More		0	0
Estimated Fair Value - Total		33,404	30,625
Gross Unrealized Losses - Total		$ (2,584)	$ (3,425)
[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 - Maturi

Investment Information - Maturity profile of available for sale securities) (Details) - USD ($) $ in Thousands		Jun. 30, 2016	Dec. 31, 2015
Estimated Fair Value:
Estimated fair value		$ 11,050,464	$ 10,459,353
Amortized Cost:
Amortized cost		10,879,863	10,515,440
Fixed maturities
Estimated Fair Value:
Due in one year or less		247,256	337,898
Due after one year through five years		5,077,739	4,644,516
Due after five years through 10 years		2,772,938	2,214,413
Due after 10 years		625,155	496,302
Single maturity date		8,723,088	7,693,129
Estimated fair value	[1]	11,370,136	10,832,657
Amortized Cost:
Due in one year or less		244,247	341,595
Due after one year through five years		5,036,912	4,677,230
Due after five years through 10 years		2,699,463	2,228,638
Due after 10 years		602,418	497,174
Single maturity date		8,583,040	7,744,637
Amortized cost	[1]	11,197,363	10,892,980
Fixed maturities | Mortgage backed securities
Estimated Fair Value:
Securities without single maturity date		656,891	754,870
Amortized Cost:
Securities without single maturity date		645,095	750,332
Fixed maturities | Commercial mortgage backed securities
Estimated Fair Value:
Securities without single maturity date		624,391	764,152
Amortized Cost:
Securities without single maturity date		611,541	767,861
Fixed maturities | Asset backed securities
Estimated Fair Value:
Securities without single maturity date		1,365,766	1,620,506
Amortized Cost:
Securities without single maturity date		$ 1,357,687	$ 1,630,150
[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	Jun. 30, 2016	Dec. 31, 2015
Disclosure Investment Information [Abstract]
Fair value of cash collateral received on securities lending	$ 75,900	$ 52,700
Approximate fair value of sub-prime securities backing the securities lending program		3,000
Fair value of non-cash collateral received on securities lending	262,400	336,700
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	338,318	393,844
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	338,318	393,844
US government and government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	294,000	327,612
Corporate bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	33,120	55,086
Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	11,198	11,146
Overnight and continuous
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	286,502	297,536
Overnight and continuous | US government and government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	242,184	235,728
Overnight and continuous | Corporate bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	33,120	55,086
Overnight and continuous | Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	11,198	6,722
Less than 30 days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	21,539	4,424
Less than 30 days | US government and government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	21,539	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	4,424
30 - 90 days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	4,109	82,286
30 - 90 days | US government and government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	4,109	82,286
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	26,168	9,598
90 days or more | US government and government agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities lending payable	26,168	9,598
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) - USD ($) $ in Thousands		Jun. 30, 2016	Dec. 31, 2015
Schedule Of Other Investments [Line Items]
Other investments and fair value option investments		$ 1,848,697	$ 1,971,447
Available for sale
Schedule Of Other Investments [Line Items]
Other investments and fair value option investments		182,957	300,476
Available for sale | Asian and emerging markets
Schedule Of Other Investments [Line Items]
Other investments and fair value option investments		109,767	206,861
Available for sale | Investment grade fixed income
Schedule Of Other Investments [Line Items]
Other investments and fair value option investments		33,549	31,370
Available for sale | Credit related funds
Schedule Of Other Investments [Line Items]
Other investments and fair value option investments		1,698	22,512
Available for sale | Other
Schedule Of Other Investments [Line Items]
Other investments and fair value option investments		37,943	39,733
Fair value option
Schedule Of Other Investments [Line Items]
Other investments and fair value option investments		1,665,740	1,670,971
Fair value option | Asian and emerging markets
Schedule Of Other Investments [Line Items]
Other investments and fair value option investments		112,265	34,761
Fair value option | Investment grade fixed income
Schedule Of Other Investments [Line Items]
Other investments and fair value option investments		65,391	63,053
Fair value option | Credit related funds
Schedule Of Other Investments [Line Items]
Other investments and fair value option investments		236,184	219,049
Fair value option | Other
Schedule Of Other Investments [Line Items]
Other investments and fair value option investments	[1]	107,916	124,502
Fair value option | Term loan investments
Schedule Of Other Investments [Line Items]
Other investments and fair value option investments		1,026,543	1,108,017
Other investments par		1,115,627	1,197,143
Fair value option | Mezzanine debt funds
Schedule Of Other Investments [Line Items]
Other investments and fair value option investments		$ 117,441	$ 121,589
[1]	Includes fund investments with strategies in mortgage servicing rights, transportation, infrastructure and other.

Investment Information - Fair v

Investment Information - Fair value option (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Option, Quantitative Disclosures [Line Items]
Investments accounted for using the fair value option	$ 3,066,029	$ 2,894,494
Fixed Maturities
Fair Value, Option, Quantitative Disclosures [Line Items]
Investments accounted for using the fair value option	1,047,662	936,802
Other investments
Fair Value, Option, Quantitative Disclosures [Line Items]
Investments accounted for using the fair value option	1,665,740	1,670,971
Short-term investments
Fair Value, Option, Quantitative Disclosures [Line Items]
Investments accounted for using the fair value option	344,797	285,923
Equity securities
Fair Value, Option, Quantitative Disclosures [Line Items]
Investments accounted for using the fair value option	$ 7,830	$ 798

Investment Information - Limite

Investment Information - Limited partnership interests (Details) - USD ($) $ in Thousands		Jun. 30, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Maximum loss exposure, amount		$ 760,824	$ 675,127
Aggregate unfunded commitments		1,350,000	1,110,000
Equity method investments
Schedule of Equity Method Investments [Line Items]
Maximum loss exposure, amount	[1]	676,893	584,158
Aggregate unfunded commitments		794,700	535,400
Fair value option
Schedule of Equity Method Investments [Line Items]
Maximum loss exposure, amount	[2]	83,931	90,969
Aggregate unfunded commitments		$ 26,600	$ 22,700
[1]	Aggregate unfunded commitments were $794.7 million at June 30, 2016, compared to $535.4 million at December 31, 2015.
[2]	Aggregate unfunded commitments were $26.6 million at June 30, 2016, compared to $22.7 million at December 31, 2015.

Investment Information - Net in

Investment Information - Net investment income (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net investment income:
Gross investment income		$ 109,341	$ 102,600	$ 220,700	$ 201,562
Investment expenses		(21,003)	(15,637)	(38,627)	(35,605)
Net investment income		88,338	86,963	182,073	165,957
Fixed Maturities
Net investment income:
Gross investment income		77,994	71,275	151,667	139,871
Term loan investments
Net investment income:
Gross investment income		18,608	18,033	38,620	32,777
Equity securities (dividends)
Net investment income:
Gross investment income		3,663	2,578	7,098	5,257
Short-term investments
Net investment income:
Gross investment income		816	225	1,312	421
Other
Net investment income:
Gross investment income	[1]	$ 8,260	$ 10,489	$ 22,003	$ 23,236
[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		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net realized gains and losses:
Available for sale securities, gross gains on investment sales		$ 74,695	$ 82,233	$ 182,514	$ 179,824
Available for sale securities, gross losses on investment sales		(43,293)	(58,974)	(106,424)	(114,134)
Derivative instruments	[1]	20,334	(41,496)	41,066	(4,820)
Other	[2]	(15,066)	(8,638)	(20,895)	(13,226)
Net realized gains (losses)		68,218	(35,725)	105,542	47,623
Fixed Maturities
Net realized gains and losses:
Change in fair value of assets and liabilities accounted for using the fair value option		18,632	(5,191)	18,299	(8,493)
Other investments
Net realized gains and losses:
Change in fair value of assets and liabilities accounted for using the fair value option		13,136	785	(8,412)	7,072
Equity securities
Net realized gains and losses:
Change in fair value of assets and liabilities accounted for using the fair value option		401	(69)	437	(71)
Short-term investments
Net realized gains and losses:
Change in fair value of assets and liabilities accounted for using the fair value option		$ (621)	$ (4,375)	$ (1,043)	$ 1,471
[1]	See Note 8 for information on the Company’s derivative instruments.
[2]	Includes the re-measurement of contingent consideration liability amounts.

Investment Information - Othe49

Investment Information - Other than temporary impairments recognized in earnings (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	$ (5,343)	$ (1,113)	$ (12,982)	$ (6,912)
Fixed Maturities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	(3,408)	(336)	(8,948)	(3,384)
Fixed Maturities | Mortgage backed securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	(82)	(326)	(555)	(1,398)
Fixed Maturities | Corporate bonds
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	(775)	(10)	(5,655)	(1,986)
Fixed Maturities | Non-US government securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	(51)	0	(232)	0
Fixed Maturities | Asset backed securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	(2,500)	0	(2,506)	0
Short-term investments
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	0	0	0	(2,341)
Equity securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	(1,935)	(124)	(3,037)	(253)
Other investments
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	$ 0	$ (653)	$ (997)	$ (934)

Investment Information - Othe50

Investment Information - Other than temporary impairments rollforward (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Rollforward:
Balance at start of period	$ 18,291	$ 24,344	$ 26,875	$ 20,196
Credit loss impairments recognized on securities not previously impaired	287	281	1,350	4,770
Credit loss impairments recognized on securities previously impaired	0	55	522	134
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	(3,731)	(3,774)	(13,900)	(4,194)
Balance at end of period	$ 14,847	$ 20,906	$ 14,847	$ 20,906

Investment Information - Restri

Investment Information - Restricted assets (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Restricted Assets [Line Items]
Restricted assets	$ 6,027,057	$ 5,526,049
Collateral or guarantees - affiliated transactions
Restricted Assets [Line Items]
Restricted assets	3,903,933	3,810,104
Collateral or guarantees - third party agreements
Restricted Assets [Line Items]
Restricted assets	1,598,266	1,286,257
Deposits with US regulatory authorities
Restricted Assets [Line Items]
Restricted assets	477,429	391,458
Deposits with non-US regulatory authorities
Restricted Assets [Line Items]
Restricted assets	$ 47,429	$ 38,230

Investment Information - Narrat

Investment Information - Narrative (Details) $ in Thousands		3 Months Ended		6 Months Ended		12 Months Ended
		Jun. 30, 2016USD ($)lots	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)lots	Jun. 30, 2015USD ($)	Dec. 31, 2015USD ($)lots
Narrative items:
Investable assets		$ 16,880,000		$ 16,880,000
Income (Loss) from Equity Method Investments		8,737	$ 16,167	15,392	$ 22,056
OTTI unrealized (losses) gains at current fair value		$ 1,500		$ 1,500		$ (1,400)
Continuous unrealized loss, qualitative disclosures:
Number of positions in an unrealized loss position (lots) | lots		1,410		1,410		3,560
Total number of positions (lots) | lots		6,280		6,280		5,550
Largest single loss		$ 3,400		$ 3,400		$ 3,100
OTTI unrealized losses (gains)	[1]			5,816		$ 6,925
Underwriting segments
Narrative items:
Investable assets		15,180,000		15,180,000
Income (Loss) from Equity Method Investments		8,737	16,167	15,392	22,056
Other
Narrative items:
Investable assets		1,700,000		1,700,000
Income (Loss) from Equity Method Investments		$ 0	$ 0	$ 0	$ 0
[1]	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 June 30, 2016, the net unrealized gain related to securities for which a non-credit OTTI was recognized in AOCI was $1.5 million, compared to a net unrealized loss of $1.4 million at December 31, 2015.

Fair Value - Fair Value Hierarc

Fair Value - Fair Value Hierarchy (Details) - Recurring - USD ($) $ in Thousands		Jun. 30, 2016	Dec. 31, 2015
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		$ 4,534,619	$ 4,032,996
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]	2,558,706	2,378,662
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]	2,558,706	2,378,662
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		500,158	627,441
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		837,202	572,604
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		79,174	99,159
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other investments at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		79,174	99,159
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		559,379	355,130
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 | US government and government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		151,726	114
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		344,797	285,923
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		7,090	798
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		55,766	68,295
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		10,716,845	10,461,895
Liabilities measured at fair value		(81,096)	(42,446)
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]	(54,668)	(30,583)
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		(26,428)	(11,863)
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]	8,744,914	8,380,127
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]	2,934,868	2,709,361
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]	656,891	754,870
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]	1,897,128	1,626,281
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]	624,391	764,152
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]	142,336	44,793
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]	1,172,745	917,664
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]	1,316,555	1,563,006
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		1,758	1,741
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		16,329	15,300
Significant Other Observable Inputs (Level 2) | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
Significant Other Observable Inputs (Level 2) | Other investments at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		0	0
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		30,625	20,022
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		1,923,219	2,044,705
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		754,034	771,733
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		17,560	57,687
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		0	0
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		101,492	81,824
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		22,850	25,444
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		0	0
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		740	0
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		1,026,543	1,108,017
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		66,516	73,868
Liabilities measured at fair value		(111,670)	(96,048)
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		(111,670)	(96,048)
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]	66,516	73,868
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]	17,305	16,368
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]	0	0
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	0
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]	49,211	57,500
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		0	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) | Other 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) | Other investments at fair value
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		0	0
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		0	0
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 | 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		0	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		0	0
Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		16,005,194	15,264,735
Liabilities measured at fair value		(192,766)	(138,494)
Estimated Fair Value | Contingent consideration liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value		(111,670)	(96,048)
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]	(54,668)	(30,583)
Estimated Fair Value | Derivative instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value		(26,428)	(11,863)
Estimated Fair Value | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		11,370,136	10,832,657
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		2,952,173	2,725,729
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		656,891	754,870
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		1,897,128	1,626,281
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		624,391	764,152
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		2,701,042	2,423,455
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		1,172,745	917,664
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		1,365,766	1,620,506
Estimated Fair Value | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		501,916	629,182
Estimated Fair Value | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		853,531	587,904
Estimated Fair Value | Other investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		182,957	300,476
Estimated Fair Value | Other investments at fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		79,174	99,159
Estimated Fair Value | 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]	103,783	201,317
Estimated Fair Value | Derivative instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		30,625	20,022
Estimated Fair Value | Fair value option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value		3,066,029	2,894,494
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		754,034	771,733
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		17,560	57,687
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		151,726	114
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		101,492	81,824
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		22,850	25,444
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		344,797	285,923
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		7,830	798
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		1,082,309	1,176,312
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]	$ 583,431	$ 494,659
[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.
[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) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		$ 72,666	$ 57,500	$ 73,868	$ 57,500
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	(1,137)	0	(2,339)	0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0	0	0	0
Purchases, issuances, sales and settlements
Purchases		776	0	776	0
Issuances		0	0	0	0
Sales		0	0	0	0
Settlements		(5,789)	0	(5,789)	0
Transfers in and/or out of Level 3		0	0	0	0
Balance at end of period		66,516	57,500	66,516	57,500
Contingent consideration liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		(100,710)	(66,461)	(96,048)	(61,845)
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	(10,923)	(4,795)	(16,121)	(8,343)
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		(37)	0	(37)	0
Purchases, issuances, sales and settlements
Purchases		0	0	0	0
Issuances		0	0	0	(1,068)
Sales		0	0	0	0
Settlements		0	0	536	0
Transfers in and/or out of Level 3		0	0	0	0
Balance at end of period		(111,670)	(71,256)	(111,670)	(71,256)
Available for sale | Asset backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		57,500	57,500	57,500	57,500
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	(2,500)	0	(2,500)	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		(5,789)	0	(5,789)	0
Transfers in and/or out of Level 3		0	0	0	0
Balance at end of period		49,211	57,500	49,211	57,500
Fair value option | Corporate bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		15,166	0	16,368	0
Total gains or (losses) (realized/unrealized) - included in earnings	[1]	1,363	0	161	0
Total gains or (losses) (realized/unrealized) - included in other comprehensive income		0	0	0	0
Purchases, issuances, sales and settlements
Purchases		776	0	776	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	0	0
Balance at end of period		$ 17,305	$ 0	$ 17,305	$ 0
[1]	Gains or losses on asset backed securities were included in net impairment losses recognized in earnings while gains or losses on corporate bonds and contingent consideration liabilities were included in net realized gains (losses).

Fair Value - Narrative (Details

Fair Value - Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Total assets and liabilities measured at fair value	$ 16,200,000	$ 15,400,000
Total assets and liabilities measured at fair value priced using non-binding broker quotes	$ 379,500	$ 317,800
Total assets and liabilities measured at fair value priced using non-binding broker quotes (percentage)	2.40%	2.10%
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	$ 791,392	$ 791,306
Reportable Legal Entities | ACGL (Parent Guarantor)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	296,914	296,874
Estimated fair value of senior notes	428,000
Reportable Legal Entities | Arch-U.S. (Subsidiary Issuer)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes	494,478	$ 494,432
Estimated fair value of senior notes	$ 602,800

Derivative Instruments (Details

Derivative Instruments (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2016		Jun. 30, 2015	Jun. 30, 2016		Jun. 30, 2015	Dec. 31, 2015
Derivative offsetting [Abstract]
Derivative assets subject to master netting agreements		$ 152,200			$ 152,200			$ 26,500
Derivative liabilities subject to master netting agreements		144,000			144,000			11,900
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments	[1]	20,334		$ (41,496)	41,066		$ (4,820)
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Asset derivatives - fair value		152,385			152,385			26,547
Liability derivatives - fair value		(144,101)			(144,101)			(11,863)
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		20,334		(41,496)	41,066		(4,820)
Not Designated as Hedging Instrument [Member] | Futures contracts
Derivative [Line Items]
Net derivatives - notional value	[2],[3]	2,287,791			2,287,791			1,797,115
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		34,871		(31,446)	61,322		(12,120)
Not Designated as Hedging Instrument [Member] | Futures contracts | Other assets
Derivative [Line Items]
Asset derivatives - fair value		1,208	[3]		1,208	[3]		2,816
Not Designated as Hedging Instrument [Member] | Futures contracts | Other liabilities
Derivative [Line Items]
Liability derivatives - fair value	[3]	(1,673)			(1,673)			(1,202)
Not Designated as Hedging Instrument [Member] | Foreign currency forward contracts
Derivative [Line Items]
Net derivatives - notional value	[2],[3]	1,436,006			1,436,006			773,619
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		(13,782)		(8,724)	(18,534)		8,095
Not Designated as Hedging Instrument [Member] | Foreign currency forward contracts | Other assets
Derivative [Line Items]
Asset derivatives - fair value	[3]	17,032			17,032			9,336
Not Designated as Hedging Instrument [Member] | Foreign currency forward contracts | Other liabilities
Derivative [Line Items]
Liability derivatives - fair value	[3]	(18,718)			(18,718)			(6,344)
Not Designated as Hedging Instrument [Member] | TBAs
Derivative [Line Items]
Net derivatives - notional value	[2],[4]	226,299			226,299			6,316
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		37		(182)	334		304
Not Designated as Hedging Instrument [Member] | TBAs | Fixed maturities available for sale
Derivative [Line Items]
Asset derivatives - fair value		121,760	[4]		121,760	[4]		6,525
Liability derivatives - fair value	[4]	(117,673)			(117,673)			0
Not Designated as Hedging Instrument [Member] | Other
Derivative [Line Items]
Net derivatives - notional value	[2],[3]	1,938,497			1,938,497			1,694,935
Net realized gains (losses) on derivative instruments
Net realized gains (losses) on derivative instruments		(792)		$ (1,144)	(2,056)		$ (1,099)
Not Designated as Hedging Instrument [Member] | Other | Other assets
Derivative [Line Items]
Asset derivatives - fair value	[3]	12,385			12,385			7,870
Not Designated as Hedging Instrument [Member] | Other | Other liabilities
Derivative [Line Items]
Liability derivatives - fair value	[3]	$ (6,037)			$ (6,037)			$ (4,317)
[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 Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Line of Credit Facility [Abstract]
Revolving credit agreement borrowings	$ 397,830	$ 530,434
Unfunded Investment Commitments [Abstract]
Investment commitments	1,350,000	1,110,000
LOC Facilities [Member]
Line of Credit Facility [Abstract]
Letters of credit outstanding, amount	416,900
Investments pledged as collateral	473,900
Other secured letter of credit facilities
Line of Credit Facility [Abstract]
Letters of credit outstanding, amount	$ 242,400
Credit Agreement
Line of Credit Facility [Abstract]
Credit facility expiration date	Jun. 30, 2019
Revolving credit agreement borrowings	$ 100,000
Unsecured revolving loan and letter of credit facility
Line of Credit Facility [Abstract]
Maximum borrowing capacity	300,000
Secured letter of credit facility
Line of Credit Facility [Abstract]
Maximum borrowing capacity	500,000
Letters of credit outstanding, amount	174,600
Remaining borrowing capacity	325,400
Unsecured letter of credit
Line of Credit Facility [Abstract]
Maximum borrowing capacity	100,000
Watford Re | Line of credit
Line of Credit Facility [Abstract]
Maximum borrowing capacity	$ 100,000
Credit facility expiration date	May 19, 2017
Letters of credit outstanding, amount	$ 198,000
Watford Re | Letter of credit
Line of Credit Facility [Abstract]
Maximum borrowing capacity	400,000
Watford Re | Other secured letter of credit facilities
Line of Credit Facility [Abstract]
Maximum borrowing capacity	$ 800,000
Credit facility expiration date	Jun. 4, 2018
Variable Interest Entity, Primary Beneficiary | Watford Re
Line of Credit Facility [Abstract]
Revolving credit agreement borrowings	$ 297,830	$ 430,434

Share Transactions - Share repu

Share Transactions - Share repurchases (Details) - Common shares - USD ($) shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Class of Stock [Line Items]
Cumulative number of shares acquired since inception of share repurchase program		125.2
Aggregate purchase price of shares acquired since inception of share repurchase program		$ 3,680
Treasury stock, shares acquired (shares)	3.2	1.1	5.9
Treasury stock, value of shares acquired	$ 199	$ 75.3	$ 361.9
Remaining authorized repurchase amount		$ 446.5

Share Transactions - Share-base

Share Transactions - Share-based compensation (Details) - $ / shares	3 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Stock appreciation rights and stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period, shares	427,379	534,267
Weighted average grant date fair value	$ 17.46	$ 16.09
Restricted shares and units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period, shares	456,217	559,332
Weighted average grant date fair value	$ 71.61	$ 62.51

Other Comprehensive Income (L60

Other Comprehensive Income (Loss) - Amounts reclassified from accumulated other comprehensive income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other-than-temporary impairment losses	$ (5,395)	$ (1,126)	$ (13,132)	$ (8,373)
Income before income taxes	263,488	132,599	455,425	454,034
Income tax expense	(14,131)	(6,780)	(30,441)	(19,458)
Net of tax	211,055	115,790	365,853	399,126
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)	31,404	23,259	76,091	65,690
Other-than-temporary impairment losses	(5,395)	(1,126)	(13,132)	(8,373)
Income before income taxes	26,009	22,133	62,959	57,317
Income tax expense	(3,915)	(919)	(8,642)	(5,171)
Net of tax	$ 22,094	$ 21,214	$ 54,317	$ 52,146

Other Comprehensive Income (L61

Other Comprehensive Income (Loss) - Components of other comprehensive income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Before tax amount:
Unrealized holding gains (losses) arising during period, before tax	$ 117,904	$ (96,630)	$ 270,078	$ (2,243)
Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss), before tax	(52)	(13)	(150)	(1,461)
Less reclassification of net realized gains included in net income, before tax	26,009	22,133	62,959	57,317
Foreign currency translation adjustments, before tax	(18,186)	11,697	(326)	(11,929)
Other comprehensive income (loss), before tax	73,657	(107,079)	206,643	(72,950)
Tax expense (benefit):
Unrealized holding gains (losses) arising during period, tax	15,444	(14,695)	34,637	(4,612)
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	3,915	919	8,642	5,171
Foreign currency translation adjustments, tax	(35)	117	512	(752)
Other comprehensive income (loss), tax	11,494	(15,497)	26,507	(10,535)
Net of tax amount:
Unrealized holding gains (losses) arising during period, net of tax	102,460	(81,935)	235,441	2,369
Portion of other-than-temporary impairment losses recognized in other comprehensive income (loss), net of tax	(52)	(13)	(150)	(1,461)
Less reclassification of net realized gains included in net income, net of tax	22,094	21,214	54,317	52,146
Foreign currency translation adjustments, net of tax	(18,151)	11,580	(838)	(11,177)
Net current period other comprehensive income (loss)	$ 62,163	$ (91,582)	$ 180,136	$ (62,415)

Guarantor Financial Informati62

Guarantor Financial Information - Condensed consolidating balance sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Assets
Total investments	$ 16,667,888	$ 15,842,941
Cash	516,591	553,326	$ 525,074	$ 485,702
Investments in subsidiaries	0	0
Due from subsidiaries and affiliates	0	0
Premiums receivable	1,260,607	983,443
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	2,034,970	1,867,373
Contractholder receivables	1,600,426	1,486,296
Prepaid reinsurance premiums	540,954	427,609
Deferred acquisition costs, net	462,906	433,477
Other assets	1,327,575	1,582,805
Total assets	24,411,917	23,177,270
Liabilities
Reserve for losses and loss adjustment expenses	9,471,647	9,125,250
Unearned premiums	2,618,359	2,333,932
Reinsurance balances payable	295,987	224,120
Contractholder payables	1,600,426	1,486,296
Collateral held for insured obligations	261,228	248,982
Deposit accounting liabilities	22,325	260,364
Senior notes	791,392	791,306
Revolving credit agreement borrowings	397,830	530,434
Due to subsidiaries and affiliates	0	0
Other liabilities	1,254,846	1,027,692
Total liabilities	16,714,040	16,028,376
Redeemable noncontrolling interests	205,366	205,182
Shareholders' Equity
Total shareholders’ equity available to Arch	6,703,922	6,204,881	6,137,515
Non-redeemable noncontrolling interests	788,589	738,831	794,880
Total shareholders’ equity	7,492,511	6,943,712	6,932,395
Total liabilities, noncontrolling interests and shareholders’ equity	24,411,917	23,177,270
Reportable Legal Entities | ACGL (Parent Guarantor)
Assets
Total investments	126	50
Cash	7,212	6,809	10,864	3,218
Investments in subsidiaries	7,092,328	6,609,174
Due from subsidiaries and affiliates	27	23
Premiums receivable	0	0
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	0	0
Contractholder receivables	0	0
Prepaid reinsurance premiums	0	0
Deferred acquisition costs, net	0	0
Other assets	13,911	4,138
Total assets	7,113,604	6,620,194
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
Deposit accounting liabilities	0	0
Senior notes	296,914	296,874
Revolving credit agreement borrowings	100,000	100,000
Due to subsidiaries and affiliates	1	26
Other liabilities	12,767	18,413
Total liabilities	409,682	415,313
Redeemable noncontrolling interests	0	0
Shareholders' Equity
Total shareholders’ equity available to Arch	6,703,922	6,204,881
Non-redeemable noncontrolling interests	0	0
Total shareholders’ equity	6,703,922	6,204,881
Total liabilities, noncontrolling interests and shareholders’ equity	7,113,604	6,620,194
Reportable Legal Entities | Arch-U.S. (Subsidiary Issuer)
Assets
Total investments	54,433	42,210
Cash	15,726	17,023	6,928	2,787
Investments in subsidiaries	1,802,240	1,712,757
Due from subsidiaries and affiliates	50,563	48,811
Premiums receivable	0	0
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	0	0
Contractholder receivables	0	0
Prepaid reinsurance premiums	0	0
Deferred acquisition costs, net	0	0
Other assets	46,982	45,522
Total assets	1,969,944	1,866,323
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
Deposit accounting liabilities	0	0
Senior notes	494,478	494,432
Revolving credit agreement borrowings	0	0
Due to subsidiaries and affiliates	35,003	35,000
Other liabilities	48,023	50,890
Total liabilities	577,504	580,322
Redeemable noncontrolling interests	0	0
Shareholders' Equity
Total shareholders’ equity available to Arch	1,392,440	1,286,001
Non-redeemable noncontrolling interests	0	0
Total shareholders’ equity	1,392,440	1,286,001
Total liabilities, noncontrolling interests and shareholders’ equity	$ 1,969,944	1,866,323
Percentage Ownership of Subsidiary	100.00%
Reportable Legal Entities | Other ACGL Subsidiaries
Assets
Total investments	$ 16,628,029	15,815,381
Cash	493,653	529,494	507,282	479,697
Investments in subsidiaries	0	0
Due from subsidiaries and affiliates	388,302	384,469
Premiums receivable	1,775,867	1,376,310
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	5,993,929	5,783,452
Contractholder receivables	1,600,426	1,486,296
Prepaid reinsurance premiums	1,690,278	1,511,795
Deferred acquisition costs, net	462,906	433,477
Other assets	1,417,947	2,119,279
Total assets	30,451,337	29,439,953
Liabilities
Reserve for losses and loss adjustment expenses	13,402,389	13,010,608
Unearned premiums	3,767,683	3,418,118
Reinsurance balances payable	811,247	603,586
Contractholder payables	1,600,426	1,486,296
Collateral held for insured obligations	261,228	248,982
Deposit accounting liabilities	22,325	463,507
Senior notes	0	0
Revolving credit agreement borrowings	297,830	430,434
Due to subsidiaries and affiliates	403,888	398,277
Other liabilities	1,373,538	1,385,500
Total liabilities	21,940,554	21,445,308
Redeemable noncontrolling interests	220,066	219,882
Shareholders' Equity
Total shareholders’ equity available to Arch	7,502,128	7,035,932
Non-redeemable noncontrolling interests	788,589	738,831
Total shareholders’ equity	8,290,717	7,774,763
Total liabilities, noncontrolling interests and shareholders’ equity	30,451,337	29,439,953
Consolidating Adjustments and Eliminations
Assets
Total investments	(14,700)	(14,700)
Cash	0	0	$ 0	$ 0
Investments in subsidiaries	(8,894,568)	(8,321,931)
Due from subsidiaries and affiliates	(438,892)	(433,303)
Premiums receivable	(515,260)	(392,867)
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses	(3,958,959)	(3,916,079)
Contractholder receivables	0	0
Prepaid reinsurance premiums	(1,149,324)	(1,084,186)
Deferred acquisition costs, net	0	0
Other assets	(151,265)	(586,134)
Total assets	(15,122,968)	(14,749,200)
Liabilities
Reserve for losses and loss adjustment expenses	(3,930,742)	(3,885,358)
Unearned premiums	(1,149,324)	(1,084,186)
Reinsurance balances payable	(515,260)	(379,466)
Contractholder payables	0	0
Collateral held for insured obligations		0
Deposit accounting liabilities	0	(203,143)
Senior notes	0	0
Revolving credit agreement borrowings	0	0
Due to subsidiaries and affiliates	(438,892)	(433,303)
Other liabilities	(179,482)	(427,111)
Total liabilities	(6,213,700)	(6,412,567)
Redeemable noncontrolling interests	(14,700)	(14,700)
Shareholders' Equity
Total shareholders’ equity available to Arch	(8,894,568)	(8,321,933)
Non-redeemable noncontrolling interests	0	0
Total shareholders’ equity	(8,894,568)	(8,321,933)
Total liabilities, noncontrolling interests and shareholders’ equity	$ (15,122,968)	$ (14,749,200)

Guarantor Financial Informati63

Guarantor Financial Information - Condensed consolidating statement of income and comprehensive income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues
Net premiums earned	$ 1,005,985	$ 943,438	$ 1,957,564	$ 1,853,702
Net investment income	88,338	86,963	182,073	165,957
Net realized gains (losses)	68,218	(35,725)	105,542	47,623
Net impairment losses recognized in earnings	(5,343)	(1,113)	(12,982)	(6,912)
Other underwriting income	25,224	7,717	30,271	19,253
Equity in net income (loss) of investment funds accounted for using the equity method	8,737	16,167	15,392	22,056
Other income (loss)	(7)	2,205	(32)	317
Total revenues	1,191,152	1,019,652	2,277,828	2,101,996
Expenses
Losses and loss adjustment expenses	584,592	519,426	1,107,541	1,013,142
Acquisition expenses	175,281	175,425	345,746	338,501
Other operating expenses	159,590	151,190	311,859	299,727
Corporate expenses	17,200	17,418	26,583	26,763
Interest expense	15,663	4,011	31,770	16,747
Net foreign exchange (gains) losses	(24,662)	19,583	(1,096)	(46,918)
Total expenses	927,664	887,053	1,822,403	1,647,962
Income (loss) before income taxes	263,488	132,599	455,425	454,034
Income tax (expense) benefit	(14,131)	(6,780)	(30,441)	(19,458)
Income (loss) before equity in net income of subsidiaries	249,357	125,819	424,984	434,576
Equity in net income of subsidiaries	0	0	0	0
Net income	249,357	125,819	424,984	434,576
Net (income) loss attributable to noncontrolling interests	(38,302)	(10,029)	(59,131)	(35,450)
Net income available to Arch	211,055	115,790	365,853	399,126
Preferred dividends	(5,485)	(5,485)	(10,969)	(10,969)
Net income (loss) available to Arch common shareholders	205,570	110,305	354,884	388,157
Comprehensive income (loss) available to Arch	273,260	24,208	546,189	336,711
Reportable Legal Entities | ACGL (Parent Guarantor)
Revenues
Net premiums earned	0	0	0	0
Net investment income	0	0	1	0
Net realized gains (losses)	0	0	0	0
Net impairment losses recognized in earnings	0	0	0	0
Other underwriting income	0	0	0	0
Equity in net income (loss) of investment funds accounted for using the equity method	0	0	0	0
Other income (loss)	(7)	0	199	0
Total revenues	(7)	0	200	0
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	17,441	16,900	26,796	25,532
Interest expense	5,929	5,862	11,863	11,718
Net foreign exchange (gains) losses	0	0	0	0
Total expenses	23,370	22,762	38,659	37,250
Income (loss) before income taxes	(23,377)	(22,762)	(38,459)	(37,250)
Income tax (expense) benefit	0	0	0	0
Income (loss) before equity in net income of subsidiaries	(23,377)	(22,762)	(38,459)	(37,250)
Equity in net income of subsidiaries	234,432	138,552	404,312	436,376
Net income	211,055	115,790	365,853	399,126
Net (income) loss attributable to noncontrolling interests	0	0	0	0
Net income available to Arch	211,055	115,790	365,853	399,126
Preferred dividends	(5,485)	(5,485)	(10,969)	(10,969)
Net income (loss) available to Arch common shareholders	205,570	110,305	354,884	388,157
Comprehensive income (loss) available to Arch	273,260	24,208	546,189	336,711
Reportable Legal Entities | Arch-U.S. (Subsidiary Issuer)
Revenues
Net premiums earned	0	0	0	0
Net investment income	775	800	1,548	805
Net realized gains (losses)	0	1	0	1
Net impairment losses recognized in earnings	0	0	0	0
Other underwriting income	0	0	0	0
Equity in net income (loss) of investment funds accounted for using the equity method	0	0	0	0
Other income (loss)	0	0	0	0
Total revenues	775	801	1,548	806
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	359	1,012	941	2,271
Interest expense	6,647	6,769	13,319	13,135
Net foreign exchange (gains) losses	0	0	0	0
Total expenses	7,006	7,781	14,260	15,406
Income (loss) before income taxes	(6,231)	(6,980)	(12,712)	(14,600)
Income tax (expense) benefit	2,086	3,697	4,330	5,110
Income (loss) before equity in net income of subsidiaries	(4,145)	(3,283)	(8,382)	(9,490)
Equity in net income of subsidiaries	19,873	14,077	42,739	28,572
Net income	15,728	10,794	34,357	19,082
Net (income) loss attributable to noncontrolling interests	0	0	0	0
Net income available to Arch	15,728	10,794	34,357	19,082
Preferred dividends	0	0	0	0
Net income (loss) available to Arch common shareholders	15,728	10,794	34,357	19,082
Comprehensive income (loss) available to Arch	28,536	(13,505)	87,185	(1,755)
Reportable Legal Entities | Other ACGL Subsidiaries
Revenues
Net premiums earned	1,005,985	943,438	1,957,564	1,853,702
Net investment income	94,097	87,154	194,358	173,164
Net realized gains (losses)	68,218	(35,726)	105,542	47,622
Net impairment losses recognized in earnings	(5,343)	(1,113)	(12,982)	(6,912)
Other underwriting income	41,450	7,717	46,769	19,253
Equity in net income (loss) of investment funds accounted for using the equity method	8,737	16,167	15,392	22,056
Other income (loss)	0	2,205	(231)	317
Total revenues	1,213,144	1,019,842	2,306,412	2,109,202
Expenses
Losses and loss adjustment expenses	584,592	519,426	1,107,541	1,013,142
Acquisition expenses	175,281	175,425	345,746	338,501
Other operating expenses	159,590	151,190	311,859	299,727
Corporate expenses	(600)	(494)	(1,154)	(1,040)
Interest expense	25,527	(7,793)	36,279	(258)
Net foreign exchange (gains) losses	(14,125)	6,942	2,370	(32,688)
Total expenses	930,265	844,696	1,802,641	1,617,384
Income (loss) before income taxes	282,879	175,146	503,771	491,818
Income tax (expense) benefit	(16,217)	(10,477)	(34,771)	(24,568)
Income (loss) before equity in net income of subsidiaries	266,662	164,669	469,000	467,250
Equity in net income of subsidiaries	0	0	0	0
Net income	266,662	164,669	469,000	467,250
Net (income) loss attributable to noncontrolling interests	(38,623)	(10,193)	(59,773)	(35,614)
Net income available to Arch	228,039	154,476	409,227	431,636
Preferred dividends	0	0	0	0
Net income (loss) available to Arch common shareholders	228,039	154,476	409,227	431,636
Comprehensive income (loss) available to Arch	300,542	50,249	592,793	383,442
Consolidating Adjustments and Eliminations
Revenues
Net premiums earned	0	0	0	0
Net investment income	(6,534)	(991)	(13,834)	(8,012)
Net realized gains (losses)	0	0	0	0
Net impairment losses recognized in earnings	0	0	0	0
Other underwriting income	(16,226)	0	(16,498)	0
Equity in net income (loss) of investment funds accounted for using the equity method	0	0	0	0
Other income (loss)	0	0	0	0
Total revenues	(22,760)	(991)	(30,332)	(8,012)
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
Interest expense	(22,440)	(827)	(29,691)	(7,848)
Net foreign exchange (gains) losses	(10,537)	12,641	(3,466)	(14,230)
Total expenses	(32,977)	11,814	(33,157)	(22,078)
Income (loss) before income taxes	10,217	(12,805)	2,825	14,066
Income tax (expense) benefit	0	0	0	0
Income (loss) before equity in net income of subsidiaries	10,217	(12,805)	2,825	14,066
Equity in net income of subsidiaries	(254,305)	(152,629)	(447,051)	(464,948)
Net income	(244,088)	(165,434)	(444,226)	(450,882)
Net (income) loss attributable to noncontrolling interests	321	164	642	164
Net income available to Arch	(243,767)	(165,270)	(443,584)	(450,718)
Preferred dividends	0	0	0	0
Net income (loss) available to Arch common shareholders	(243,767)	(165,270)	(443,584)	(450,718)
Comprehensive income (loss) available to Arch	$ (329,078)	$ (36,744)	$ (679,978)	$ (381,687)

Guarantor Financial Informati64

Guarantor Financial Information - Condensed consolidating statement of cash flows (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015
Operating Activities
Net Cash Provided by (Used in) Operating Activities		$ 541,224	$ 385,199
Investing Activities
Purchases of fixed maturity investments		(17,541,731)	(14,641,391)
Purchases of equity securities		(212,678)	(288,535)
Purchases of other investments		(650,613)	(779,678)
Proceeds from sales of fixed maturity investments		16,978,549	14,333,436
Proceeds from sales of equity securities		337,619	272,343
Proceeds from sales, redemptions and maturities of other investments		636,535	587,650
Proceeds from redemptions and maturities of fixed maturity investments		370,980	474,984
Net settlements of derivative instruments		45,174	19,006
Proceeds from investment in joint venture		0	40,000
Net (purchases) sales of short-term investments		(304,460)	3,707
Change in cash collateral related to securities lending		(18,715)	(18,329)
Contributions to subsidiaries		0	0
Intercompany loans issued		0	0
Purchase of business, net of cash acquired		(1,460)	818
Purchases of fixed assets		(8,284)	(6,396)
Change in other assets		13,416	(36,769)
Net Cash Provided By (Used For) Investing Activities		(355,668)	(39,154)
Financing Activities
Purchases of common shares under share repurchase program		(75,256)	(361,877)
Proceeds from common shares issued, net		(1,487)	2,178
Proceeds from borrowings		46,000	0
Proceeds from intercompany borrowings			0
Repayments of borrowings		(179,171)	0
Change in cash collateral related to securities lending		18,715	18,329
Dividends paid to redeemable noncontrolling interests		(8,994)	(9,313)
Dividends paid to parent	[1]	0	0
Other		(2,223)	55,018
Preferred dividends paid		(10,969)	(10,969)
Net Cash Provided By (Used For) Financing Activities		(213,385)	(306,634)
Effects of exchange rate changes on foreign currency cash		(8,906)	(39)
Increase (decrease) in cash		(36,735)	39,372
Cash beginning of year		553,326	485,702
Cash end of period		516,591	525,074
Reportable Legal Entities | ACGL (Parent Guarantor)
Operating Activities
Net Cash Provided by (Used in) Operating Activities		89,499	378,703
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
Proceeds from investment in joint venture			0
Net (purchases) sales of short-term investments		(76)	(365)
Change in cash collateral related to securities lending		0	0
Contributions to subsidiaries		(3,300)	0
Intercompany loans issued		0	0
Purchase of business, net of cash acquired		0	0
Purchases of fixed assets		(8)	(24)
Change in other assets		2,000	0
Net Cash Provided By (Used For) Investing Activities		(1,384)	(389)
Financing Activities
Purchases of common shares under share repurchase program		(75,256)	(361,877)
Proceeds from common shares issued, net		(1,487)	2,178
Proceeds from borrowings		0
Proceeds from intercompany borrowings			0
Repayments of borrowings		0
Change in cash collateral related to securities lending		0	0
Dividends paid to redeemable noncontrolling interests		0	0
Dividends paid to parent	[1]	0	0
Other		0	0
Preferred dividends paid		(10,969)	(10,969)
Net Cash Provided By (Used For) Financing Activities		(87,712)	(370,668)
Effects of exchange rate changes on foreign currency cash		0	0
Increase (decrease) in cash		403	7,646
Cash beginning of year		6,809	3,218
Cash end of period		7,212	10,864
Reportable Legal Entities | Arch-U.S. (Subsidiary Issuer)
Operating Activities
Net Cash Provided by (Used in) Operating Activities		10,732	8,282
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	20,002
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		41,500	0
Net settlements of derivative instruments		0	0
Proceeds from investment in joint venture			0
Net (purchases) sales of short-term investments		(53,729)	(12,171)
Change in cash collateral related to securities lending		0	0
Contributions to subsidiaries		0	0
Intercompany loans issued		0	(39,500)
Purchase of business, net of cash acquired		0	0
Purchases of fixed assets		0	0
Change in other assets		0	0
Net Cash Provided By (Used For) Investing Activities		(12,229)	(31,669)
Financing Activities
Purchases of common shares under share repurchase program		0	0
Proceeds from common shares issued, net		0	0
Proceeds from borrowings		0
Proceeds from intercompany borrowings			27,500
Repayments of borrowings		0
Change in cash collateral related to securities lending		0	0
Dividends paid to redeemable noncontrolling interests		0	0
Dividends paid to parent	[1]	0	0
Other		200	28
Preferred dividends paid		0	0
Net Cash Provided By (Used For) Financing Activities		200	27,528
Effects of exchange rate changes on foreign currency cash		0	0
Increase (decrease) in cash		(1,297)	4,141
Cash beginning of year		17,023	2,787
Cash end of period		15,726	6,928
Reportable Legal Entities | Other ACGL Subsidiaries
Operating Activities
Net Cash Provided by (Used in) Operating Activities		588,067	433,833
Investing Activities
Purchases of fixed maturity investments		(17,541,731)	(14,641,391)
Purchases of equity securities		(212,678)	(288,535)
Purchases of other investments		(650,613)	(779,678)
Proceeds from sales of fixed maturity investments		16,978,549	14,313,434
Proceeds from sales of equity securities		337,619	272,343
Proceeds from sales, redemptions and maturities of other investments		636,535	587,650
Proceeds from redemptions and maturities of fixed maturity investments		329,480	474,984
Net settlements of derivative instruments		45,174	19,006
Proceeds from investment in joint venture			40,000
Net (purchases) sales of short-term investments		(250,655)	16,243
Change in cash collateral related to securities lending		(18,715)	(18,329)
Contributions to subsidiaries		(2,779)	(9,290)
Intercompany loans issued		0	(27,500)
Purchase of business, net of cash acquired		(1,460)	818
Purchases of fixed assets		(8,276)	(6,372)
Change in other assets		11,416	(36,769)
Net Cash Provided By (Used For) Investing Activities		(348,134)	(83,386)
Financing Activities
Purchases of common shares under share repurchase program		0	0
Proceeds from common shares issued, net		6,079	9,290
Proceeds from borrowings		46,000
Proceeds from intercompany borrowings			39,500
Repayments of borrowings		(179,171)
Change in cash collateral related to securities lending		18,715	18,329
Dividends paid to redeemable noncontrolling interests		(9,632)	(9,632)
Dividends paid to parent	[1]	(146,436)	(435,300)
Other		(2,423)	54,990
Preferred dividends paid		0	0
Net Cash Provided By (Used For) Financing Activities		(266,868)	(322,823)
Effects of exchange rate changes on foreign currency cash		(8,906)	(39)
Increase (decrease) in cash		(35,841)	27,585
Cash beginning of year		529,494	479,697
Cash end of period		493,653	507,282
Consolidating Adjustments and Eliminations
Operating Activities
Net Cash Provided by (Used in) Operating Activities		(147,074)	(435,619)
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
Proceeds from investment in joint venture			0
Net (purchases) sales of short-term investments		0	0
Change in cash collateral related to securities lending		0	0
Contributions to subsidiaries		6,079	9,290
Intercompany loans issued		0	67,000
Purchase of business, net of cash acquired		0	0
Purchases of fixed assets		0	0
Change in other assets		0	0
Net Cash Provided By (Used For) Investing Activities		6,079	76,290
Financing Activities
Purchases of common shares under share repurchase program		0	0
Proceeds from common shares issued, net		(6,079)	(9,290)
Proceeds from borrowings		0
Proceeds from intercompany borrowings			(67,000)
Repayments of borrowings		0
Change in cash collateral related to securities lending		0	0
Dividends paid to redeemable noncontrolling interests		638	319
Dividends paid to parent	[1]	146,436	435,300
Other		0	0
Preferred dividends paid		0	0
Net Cash Provided By (Used For) Financing Activities		140,995	359,329
Effects of exchange rate changes on foreign currency cash		0	0
Increase (decrease) in cash		0	0
Cash beginning of year		0	0
Cash end of period		$ 0	$ 0
[1]	Included in net cash provided by (used for) operating activities in the ACGL (Parent Guarantor) column.

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Effective tax rate on income before income taxes (percentage)	6.70%	4.30%
Net deferred tax assets	$ 113		$ 135.7
Income taxes paid	$ 26.6	$ 26

Transactions with Related Par66

Transactions with Related Parties (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Related Party Transaction [Line Items]
Investment commitments	$ 1,350,000		$ 1,110,000
Purchases of other investments	650,613	$ 779,678
Common director | The Carlyle Group
Related Party Transaction [Line Items]
Investment commitments	770,900
Unfunded commitments	513,100
Purchases of other investments	56,600	25,600
Aggregate cash distributions received	$ 13,800	$ 19,800