Validus 10-Q 27 Jul 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 26, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	VALIDUS HOLDINGS LTD
Entity Central Index Key	1,348,259
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		79,329,027

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets
Fixed maturity investments trading, at fair value (amortized cost: 2018—$5,651,953; 2017—$5,876,261)	$ 5,559,953	$ 5,858,348
Short-term investments trading, at fair value (amortized cost: 2018—$3,728,930; 2017—$3,381,714)	3,728,894	3,381,757
Other investments, at fair value (cost: 2018—$341,883; 2017—$330,416)	366,184	355,218
Investments in investment affiliates, equity method (cost: 2018—$72,135; 2017—$61,944)	127,247	100,137
Cash and cash equivalents	719,219	754,990
Restricted cash	286,279	394,663
Total investments and cash	10,787,776	10,845,113
Premiums receivable	1,947,462	939,487
Deferred acquisition costs	317,834	213,816
Prepaid reinsurance premiums	336,384	132,938
Securities lending collateral	2,117	2,717
Loss reserves recoverable	970,950	1,233,997
Paid losses recoverable	71,876	46,873
Income taxes recoverable	11,023	9,044
Deferred tax asset	60,438	52,467
Receivable for investments sold	15,662	12,182
Intangible assets	167,052	171,411
Goodwill	229,573	229,573
Accrued investment income	31,082	29,096
Other assets	549,841	508,165
Total assets	15,499,070	14,426,879
Liabilities
Reserve for losses and loss expenses	4,699,599	4,831,390
Unearned premiums	2,190,884	1,147,186
Reinsurance balances payable	406,081	331,645
Securities lending payable	2,117	2,717
Deferred tax liability	2,142	4,600
Payable for investments purchased	60,275	74,496
Accounts payable and accrued expenses	576,260	1,225,875
Notes payable to AlphaCat investors	1,206,671	1,108,364
Senior notes payable	245,664	245,564
Debentures payable	538,751	539,158
Total liabilities	9,928,444	9,510,995
Commitments and contingent liabilities
Redeemable noncontrolling interests	1,390,233	1,004,094
Shareholders' equity
Preferred shares (Issued and Outstanding: 2018—16,000; 2017—16,000)	400,000	400,000
Common shares (Issued: 2018—163,186,889; 2017—161,994,491; Outstanding: 2018—80,511,948; 2017—79,319,550)	28,558	28,349
Treasury shares (2018—82,674,941; 2017—82,674,941)	(14,468)	(14,468)
Additional paid-in capital	816,282	814,641
Accumulated other comprehensive income (loss)	9,859	(22,192)
Retained earnings	2,568,905	2,688,742
Total shareholders' equity available to Validus	3,809,136	3,895,072
Noncontrolling interests	371,257	16,718
Total shareholders' equity	4,180,393	3,911,790
Total liabilities, noncontrolling interests and shareholders’ equity	$ 15,499,070	$ 14,426,879

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Assets
Fixed maturities, at amortized cost or cost	$ 5,651,953	$ 5,876,261
Short-term investments, at amortized cost or cost	3,728,930	3,381,714
Other investments, at amortized cost or cost	341,883	330,416
Investments in investment affiliates, at cost	$ 72,135	$ 61,944
Preferred shares - Shareholders' Equity
Preferred shares, shares issued	16,000	16,000
Preferred shares, shares outstanding	16,000	16,000
Common Shares - Shareholders' Equity
Common shares, shares issued	163,186,889	161,994,491	161,934,355	161,279,976
Common shares, shares outstanding	80,511,948	79,319,550	79,518,581
Treasury shares, common shares	82,674,941	82,674,941	82,415,774

Consolidated Statements of Inco

Consolidated Statements of Income and Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues
Gross premiums written	$ 847,206	$ 792,902	$ 2,679,662	$ 1,983,759
Reinsurance premiums ceded	(107,567)	(56,222)	(483,861)	(256,328)
Net premiums written	739,639	736,680	2,195,801	1,727,431
Change in unearned premiums	(3,032)	(105,653)	(840,252)	(521,028)
Net premiums earned	736,607	631,027	1,355,549	1,206,403
Net investment income	57,560	44,241	109,632	84,455
Net realized (losses) gains on investments	(7,394)	2,274	(5,194)	1,110
Change in net unrealized (losses) gains on investments	(10,730)	16,321	(68,111)	29,669
Income from investment affiliates	2,178	9,466	15,246	14,654
Other insurance related (loss) income and other (loss) income	(16,116)	1,339	9,424	2,669
Foreign exchange losses	(526)	(7,329)	(1)	(5,760)
Total revenues	761,579	697,339	1,416,545	1,333,200
Expenses
Losses and loss expenses	476,610	296,149	798,155	565,734
Policy acquisition costs	118,781	117,268	235,237	228,896
General and administrative expenses	120,862	96,349	235,588	184,273
Share compensation expenses	16,040	11,146	25,769	20,637
Finance expenses	14,310	14,209	28,573	28,152
Transaction expenses	3,837	4,427	11,593	4,427
Total expenses	750,440	539,548	1,334,915	1,032,119
Income before taxes and (income) attributable to AlphaCat investors	11,139	157,791	81,630	301,081
Tax benefit	7,151	987	13,984	4,536
(Income) attributable to AlphaCat investors	(29,849)	(11,830)	(40,711)	(19,333)
Net (loss) income	(11,559)	146,948	54,903	286,284
Net (income) attributable to noncontrolling interests	(35,511)	(43,650)	(100,223)	(86,222)
Net (loss) income (attributable) available to Validus	(47,070)	103,298	(45,320)	200,062
Dividends on preferred shares	(5,828)	(2,203)	(11,656)	(4,406)
Net (loss) income (attributable) available to Validus common shareholders	(52,898)	101,095	(56,976)	195,656
Comprehensive (loss) income
Net (loss) income	(11,559)	146,948	54,903	286,284
Other comprehensive income (loss), net of tax:
Change in foreign currency translation adjustments	(2,737)	1,489	(900)	2,086
Change in minimum pension liability	342	1,184	304	1,252
Change in fair value of cash flow hedges	3,035	(144)	31,798	(46)
Other comprehensive income, net of tax	640	2,529	31,202	3,292
Comprehensive (income) attributable to noncontrolling interests	(35,511)	(43,650)	(100,223)	(86,222)
Comprehensive (loss) income (attributable) available to Validus	$ (46,430)	$ 105,827	$ (14,118)	$ 203,354
(Loss) earnings per common share
Basic (loss) earnings per share (attributable) available to Validus common shareholders	$ (0.66)	$ 1.28	$ (0.72)	$ 2.47
(Loss) earnings per diluted share (attributable) available to Validus common shareholders	(0.66)	1.25	(0.72)	2.42
Cash dividends declared per common share	$ 0.38	$ 0.38	$ 0.76	$ 0.76
Weighted average number of common shares and common share equivalents outstanding:
Basic (in shares)	79,650,474	79,270,561	79,488,081	79,202,116
Diluted (in shares)	79,650,474	80,872,451	79,488,081	80,861,998

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Preferred shares	Common shares	Treasury shares	Additional paid-in capital	Accumulated other comprehensive loss	Retained earnings
Balance - Beginning of period at Dec. 31, 2016		$ 150,000	$ 28,224	$ (14,376)	$ 821,023	$ (23,216)	$ 2,876,636
Preferred shares issued		250,000
Common shares issued (redeemed), net			115		(12,076)
Repurchase of common shares				(47)	(13,949)
Offering expenses on preferred shares					(8,314)
Share compensation expenses					20,637
Other comprehensive (loss) income	$ 3,292					3,292
Amounts reclassified from accumulated other comprehensive income (loss)	0
Net (loss) income	286,284						286,284
Net (income) attributable to noncontrolling interests	(86,222)						(86,222)
Dividends on common shares							(62,174)
Dividends on preferred shares							(4,406)
Balance - End of period at Jun. 30, 2017	4,211,431	400,000	28,339	(14,423)	807,321	(19,924)	3,010,118
Noncontrolling interests at Jun. 30, 2017	415,658
Total shareholders' equity at Jun. 30, 2017	4,627,089
Balance - Beginning of period at Mar. 31, 2017						(22,453)
Other comprehensive (loss) income	2,529
Net (loss) income	146,948
Net (income) attributable to noncontrolling interests	(43,650)
Balance - End of period at Jun. 30, 2017	4,211,431	400,000	28,339	(14,423)	807,321	(19,924)	3,010,118
Noncontrolling interests at Jun. 30, 2017	415,658
Total shareholders' equity at Jun. 30, 2017	4,627,089
Balance - Beginning of period at Dec. 31, 2017	3,895,072	400,000	28,349	(14,468)	814,641	(22,192)	2,688,742
Preferred shares issued		0
Common shares issued (redeemed), net			209		(24,128)
Repurchase of common shares				0	0
Offering expenses on preferred shares					0
Share compensation expenses					25,769
Other comprehensive (loss) income	31,202					31,202
Amounts reclassified from accumulated other comprehensive income (loss)						849
Net (loss) income	54,903						54,903
Net (income) attributable to noncontrolling interests	(100,223)						(100,223)
Dividends on common shares							(62,861)
Dividends on preferred shares							(11,656)
Balance - End of period at Jun. 30, 2018	3,809,136	400,000	28,558	(14,468)	816,282	9,859	2,568,905
Noncontrolling interests at Jun. 30, 2018	371,257
Total shareholders' equity at Jun. 30, 2018	4,180,393
Balance - Beginning of period at Mar. 31, 2018						9,405
Other comprehensive (loss) income	640
Amounts reclassified from accumulated other comprehensive income (loss)						(186)
Net (loss) income	(11,559)
Net (income) attributable to noncontrolling interests	(35,511)
Balance - End of period at Jun. 30, 2018	3,809,136	$ 400,000	$ 28,558	$ (14,468)	$ 816,282	$ 9,859	$ 2,568,905
Noncontrolling interests at Jun. 30, 2018	371,257
Total shareholders' equity at Jun. 30, 2018	$ 4,180,393

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows provided by (used in) operating activities
Net income	$ 54,903	$ 286,284
Adjustments to reconcile net income to cash provided by operating activities:
Share compensation expenses	25,769	20,637
Loss on redemption of AlphaCat ILS fund	0	402
Amortization of discount on Senior Notes	54	54
(Income) from investment and operating affiliates	(15,246)	(14,654)
Net realized and change in net unrealized losses (gains) on investments	73,305	(30,779)
Amortization of intangible assets	4,359	3,995
Foreign exchange losses (gains) included in net income	8,837	(9,686)
Amortization of premium on fixed maturity investments	6,853	7,012
Change in operational balance sheet items:
Premiums receivable	(1,010,121)	(648,195)
Deferred acquisition costs	(104,018)	(97,746)
Prepaid reinsurance premiums	(203,446)	(30,684)
Loss reserves recoverable	261,992	(113,508)
Paid losses recoverable	(24,994)	17,500
Reserve for losses and loss expenses	(125,377)	199,985
Unearned premiums	1,043,698	488,198
Reinsurance balances payable	75,018	111,488
Other operational balance sheet items, net	91,562	(137,618)
Net cash provided by operating activities	163,148	52,685
Cash flows provided by (used in) investing activities
Proceeds on sales of fixed maturity investments	1,739,391	1,632,371
Proceeds on maturities of fixed maturity investments	316,335	247,394
Purchases of fixed maturity investments	(1,867,720)	(1,682,609)
Purchases of short-term investments, net	(347,138)	(88,623)
Purchases of other investments, net	(12,487)	(33,870)
Decrease in securities lending collateral	600	7,265
(Investments in) distributions from investment affiliates, net	(11,864)	11,708
Purchase of subsidiary, net of cash	0	(183,923)
Net cash used in investing activities	(182,883)	(90,287)
Cash flows provided by (used in) financing activities
Net proceeds on issuance of notes payable to AlphaCat investors	98,720	269,645
Net proceeds on issuance of preferred shares	0	241,686
Redemption of common shares, net	(23,919)	(11,961)
Purchases of common shares under share repurchase program	0	(13,996)
Dividends paid on preferred shares	(11,656)	(4,406)
Dividends paid on common shares	(68,518)	(63,286)
Decrease in securities lending payable	(600)	(7,265)
Third party investments in redeemable noncontrolling interests	466,550	210,200
Third party redemptions of redeemable noncontrolling interests	(233,478)	(79,334)
Third party investments in noncontrolling interests	321,900	258,300
Third party distributions of noncontrolling interests	(20,118)	(96,125)
Third party subscriptions deployed on funds and sidecars, net	(645,233)	(171,952)
Net cash (used in) provided by financing activities	(116,352)	531,506
Effect of foreign currency rate changes on cash and cash equivalents and restricted cash	(8,068)	10,608
Net (decrease) increase in cash and cash equivalents and restricted cash	(144,155)	504,512
Cash and cash equivalents and restricted cash—beginning of period	1,149,653	490,932
Cash and cash equivalents and restricted cash—end of period	1,005,498	995,444
Supplemental disclosure of cash flow information:
Taxes paid during the period	868	568
Interest paid during the period	$ 25,090	$ 27,186

Basis of preparation and consol

Basis of preparation and consolidation	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of presentation and consolidation	Basis of preparation and consolidation These unaudited Consolidated Financial Statements (the “Consolidated Financial Statements”) have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 in Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In addition, the year-end balance sheet data was derived from audited financial statements but does not include all disclosures required by U.S. GAAP. This Quarterly Report on Form 10-Q should be read in conjunction with the financial statements and related notes included in Validus Holdings, Ltd.’s (the “Company”) Annual Report on Form 10-K for the year ended December 31, 2017 , as filed with the U.S. Securities and Exchange Commission (the “SEC”). During the fourth quarter of 2017, the Company changed its reportable segments to “Reinsurance,” “Insurance,” and “Asset Management.” The change in reportable segments and primary lines of business had no impact on the Company’s historical consolidated financial positions, results of operations or cash flows as previously reported. Where applicable, all prior periods presented have been reclassified to conform to this new presentation. The Company consolidates in these Consolidated Financial Statements the results of operations and financial position of every voting interest entity (“VOE”) in which the Company has a controlling financial interest and variable interest entity (“VIE”) in which the Company is considered to be the primary beneficiary. The consolidation assessment, including the determination as to whether an entity qualifies as a VIE or VOE, depends on the facts and circumstances surrounding each entity. In the opinion of management, these unaudited Consolidated Financial Statements reflect all adjustments (including normal recurring adjustments) considered necessary for a fair statement of the Company’s financial position and results of operations as at the end of and for the periods presented. All significant intercompany accounts and transactions have been eliminated. The results of operations for any interim period are not necessarily indicative of the results for a full year. The preparation of these Consolidated Financial Statements in conformity with U.S. 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. While the amounts included in the Consolidated Financial Statements reflect management’s best estimates and assumptions, actual results could differ from those estimates. The Company’s principal estimates include: • the reserve for losses and loss expenses; • the premium written on a line slip or proportional basis; • the valuation of goodwill and intangible assets; • the loss reserves recoverable, including the provision for uncollectible amounts; and • the valuation of invested assets and other financial instruments. The term “ASC” used in these notes refers to Accounting Standard Codification issued by the United States Financial Accounting Standards Board (the “FASB”).

Recent accounting pronouncement

Recent accounting pronouncements	6 Months Ended
	Jun. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent accounting pronouncements	Recent accounting pronouncements There have been no accounting pronouncements issued or adopted during the quarter ended June 30, 2018 that warrant disclosure in the Consolidated Financial Statements.

Business combinations

Business combinations	6 Months Ended
	Jun. 30, 2018
Business Combinations [Abstract]
Business combination	Business combinations American International Group, Inc. (“AIG”) On July 18, 2018, the Company completed its previously announced definitive agreement and plan of merger (the “Merger Agreement”) with American International Group, Inc. (“AIG”) in accordance with Section 105 of the Bermuda Companies Act 1981. Pursuant to the Merger Agreement the Company merged with an existing AIG subsidiary in accordance with the Bermuda Companies Act 1981 (the “Merger”), with the Company continuing as the surviving corporation and as a wholly-owned subsidiary of AIG. Pursuant to the Merger Agreement, each issued and outstanding common share, par value $0.175 per common share, of the Company, other than shares that were owned by the Company as treasury shares, owned by a subsidiary of the Company, owned by AIG or any of its subsidiaries or that were subject to any Company Award (as defined in the Merger Agreement), were converted into the right to receive $68.00 in cash, without interest and subject to any applicable tax withholdings. Each of the Company’s issued and outstanding Series A and Series B Preferred Shares remains issued and outstanding, and continues to be listed on the NYSE and registered under the Exchange Act. Also on July 18, 2018, in connection with the consummation of the Merger, the Company notified the New York Stock Exchange (“NYSE”) of the completion of the Merger and requested that trading in the Common Shares be withdrawn from listing on the NYSE. The NYSE filed a notification of removal from listing on Form 25 with the Securities and Exchange Commission (“SEC”) with respect to the Common Shares to report the delisting of the Common Shares from the NYSE and to suspend trading of the Common Shares on the NYSE prior to the opening of trading on July 18, 2018. On July 26, 2018 the Company filed with the SEC a certificate of notice of termination on Form 15 with respect to its Common Shares, requesting that the Common Shares be deregistered under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and that the reporting obligations of the Company with respect to the Common Shares under Sections 13 and 15(d) of the Exchange Act be suspended. Crop Risk Services (“CRS”) On May 1, 2017, Western World, a wholly–owned subsidiary of the Company acquired all of the outstanding capital stock of CRS for an aggregate purchase price of $185,576 in cash. CRS is a primary crop insurance managing general agent (“MGA”) based in Decatur, Illinois with 1,170 agents across 36 states. CRS does not have insurance licenses of its own, but acts solely as an MGA in that it can produce business for any properly licensed entity on a commission basis. Concurrent with closing of the transaction, Stratford, a wholly–owned subsidiary of Western World, was granted the required licenses to write crop insurance in the United States and executed several agreements to transfer the related agriculture book of business to Stratford. The CRS acquisition was undertaken to expand the Company’s presence in U.S. primary specialty lines. For segmental reporting purposes, the results of CRS’ operations, including the related agricultural book of business have been included within the Insurance segment in the Consolidated Financial Statements from the date of acquisition. For further information regarding the acquisition of CRS please refer to Note 5, “Business combinations,” included within the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 .

Investments

Investments	6 Months Ended
	Jun. 30, 2018
Investments [Abstract]
Investments	Investments Managed investments represent assets governed by the Company’s investment policy statement (“IPS”) whereas, non-managed investments represent assets held in support of consolidated AlphaCat VIEs which are not governed by the Company’s IPS. Refer to Note 6 , “Variable interest entities,” for further details. The amortized cost (or cost) and fair values of the Company’s investments as at June 30, 2018 and December 31, 2017 were as follows: June 30, 2018 December 31, 2017 Amortized Cost or Cost Fair Value Amortized Fair Value Managed investments U.S. government and government agency $ 613,130 $ 604,392 $ 733,510 $ 727,397 Non-U.S. government and government agency 285,514 282,263 310,845 312,239 U.S. states, municipalities and political subdivisions 191,065 189,437 201,347 201,303 Agency residential mortgage-backed securities 956,254 929,859 984,387 978,049 Non-agency residential mortgage-backed securities 48,061 47,600 40,264 40,373 U.S. corporate 1,459,190 1,436,885 1,531,498 1,533,395 Non-U.S. corporate 410,287 403,385 420,522 422,249 Bank loans 480,593 471,212 450,320 442,951 Asset-backed securities 719,803 714,434 657,234 658,303 Commercial mortgage-backed securities 309,080 301,544 315,002 312,395 Total fixed maturities 5,472,977 5,381,011 5,644,929 5,628,654 Short-term investments 218,071 218,035 229,968 230,011 Other investments Hedge funds 6,954 15,888 6,954 15,774 Private equity investments 64,921 79,185 63,684 78,407 Fixed income investment funds 208,400 209,503 203,167 204,426 Overseas deposits 61,608 61,608 56,611 56,611 Total other investments 341,883 366,184 330,416 355,218 Investments in investment affiliates (a) 72,135 127,247 61,944 100,137 Total managed investments $ 6,105,066 $ 6,092,477 $ 6,267,257 $ 6,314,020 Non-managed investments Catastrophe bonds $ 178,976 $ 178,942 $ 231,332 $ 229,694 Short-term investments 3,510,859 3,510,859 3,151,746 3,151,746 Total non-managed investments 3,689,835 3,689,801 3,383,078 3,381,440 Total investments $ 9,794,901 $ 9,782,278 $ 9,650,335 $ 9,695,460 (a) The Company’s investments in investment affiliates have been treated as equity method investments with the corresponding gains and losses recorded in income as “Income from investment affiliates.” (a) Fixed maturity investments The following table sets forth certain information regarding Standard & Poor’s credit quality ratings (or an equivalent rating with another recognized rating agency) of the Company’s fixed maturity investments as at June 30, 2018 and December 31, 2017 : June 30, 2018 December 31, 2017 Fair Value % of Total Fair Value % of Total Managed fixed maturities AAA $ 2,560,857 46.2 % $ 2,715,074 46.4 % AA 417,814 7.5 % 442,397 7.6 % A 1,102,419 19.8 % 1,137,795 19.4 % BBB 797,698 14.3 % 828,392 14.1 % Total investment grade managed fixed maturities 4,878,788 87.8 % 5,123,658 87.5 % BB 157,241 2.8 % 168,967 2.9 % B 227,954 4.1 % 237,131 4.0 % CCC 20,219 0.4 % 18,217 0.3 % CC 564 — % — — % NR 96,245 1.7 % 80,681 1.4 % Total non-investment grade managed fixed maturities 502,223 9.0 % 504,996 8.6 % Total managed fixed maturities $ 5,381,011 96.8 % $ 5,628,654 96.1 % Non-managed catastrophe bonds AAA $ 250 — % $ — — % Total investment grade non-managed catastrophe bonds 250 — % — — % BB $ 6,632 0.2 % $ 22,110 0.3 % B 2,626 — % 3,265 0.1 % NR 169,434 3.0 % 204,319 3.5 % Total non-investment grade non-managed catastrophe bonds 178,692 3.2 % 229,694 3.9 % Total non-managed catastrophe bonds 178,942 3.2 % 229,694 3.9 % Total fixed maturities $ 5,559,953 100.0 % $ 5,858,348 100.0 % The amortized cost and fair values for the Company’s fixed maturity investments held at June 30, 2018 and December 31, 2017 are shown below by contractual maturity. Actual maturity may differ from contractual maturity due to prepayment rights associated with certain investments. June 30, 2018 December 31, 2017 Amortized Cost or Cost Fair Value Amortized Cost or Cost Fair Value Managed fixed maturities Due in one year or less $ 361,061 $ 359,094 $ 343,360 $ 343,541 Due after one year through five years 2,333,731 2,295,728 2,527,018 2,513,620 Due after five years through ten years 556,784 547,685 577,347 577,109 Due after ten years 188,203 185,067 200,317 205,264 3,439,779 3,387,574 3,648,042 3,639,534 Asset-backed and mortgage-backed securities 2,033,198 1,993,437 1,996,887 1,989,120 Total managed fixed maturities $ 5,472,977 $ 5,381,011 $ 5,644,929 $ 5,628,654 Non-managed catastrophe bonds Due in one year or less $ 47,918 $ 46,922 $ 88,797 $ 88,367 Due after one year through five years 130,433 131,395 140,035 138,844 Due after five years through ten years 625 625 2,500 2,483 Total non-managed catastrophe bonds 178,976 178,942 231,332 229,694 Total fixed maturities $ 5,651,953 $ 5,559,953 $ 5,876,261 $ 5,858,348 (b) Other investments The following tables set forth certain information regarding the Company’s other investment portfolio as at June 30, 2018 and December 31, 2017 : June 30, 2018 Fair Value Investments with redemption restrictions Investments without redemption restrictions Redemption frequency (a) Redemption notice period (a) Hedge funds $ 15,888 $ 15,888 $ — Private equity investments 79,185 79,185 — Fixed income investment funds 209,503 209,503 — Overseas deposits 61,608 61,608 — Total other investments $ 366,184 $ 366,184 $ — December 31, 2017 Fair Value Investments with redemption restrictions Investments without redemption restrictions Redemption frequency (a) Redemption notice period (a) Hedge funds 15,774 15,774 — Private equity investments 78,407 78,407 — Fixed income investment funds 204,426 200,532 3,894 Daily Daily to 2 days Overseas deposits 56,611 56,611 — Total other investments $ 355,218 $ 351,324 $ 3,894 (a) The redemption frequency and notice periods only apply to investments without redemption restrictions. Other investments include investments in various funds and pooled investment schemes. These alternative investments employ various investment strategies primarily involving, but not limited to, investments in collateralized obligations, fixed income securities, private equities, distressed debt and equity securities. Certain debt-like investments totaling $196,379 ( December 31, 2017 : $186,734 ) are either rated or consist of underlying securities or instruments which carry credit ratings issued by nationally recognized statistical rating organizations. Other equity-like investments totaling $169,805 ( December 31, 2017 : $168,484 ) are unrated given the nature of their underlying assets, such as private equity investments, and as such do not carry credit ratings. Certain securities included in other investments are subject to redemption restrictions. Distributions from these funds will be received as the underlying investments of the funds are liquidated. Currently, it is not known by the Company when these underlying assets will be sold by their investment managers; however, it is estimated that the majority of the underlying assets of the investments will liquidate over five to ten -year periods from inception of the funds. Furthermore, the underlying investments held in the overseas deposit funds are liquid and will generally trade freely in an open market. However, the Company’s ability to withdraw from the overseas deposit funds is restricted by annual and quarterly funding and release processes for Lloyd’s market participants. The Company’s maximum exposure to any of these alternative investments is limited to the invested amounts and any remaining capital commitments. Refer to Note 15 , “Commitments and contingencies,” for further details. As at June 30, 2018 , the Company does not have any plans to sell any of the other investments listed above. (c) Investments in investment affiliates Included in the Company’s managed investment portfolio as at June 30, 2018 are investments in Aquiline Financial Services Fund II L.P. (“Aquiline II”), Aquiline Financial Services Fund III L.P. (“Aquiline III”), Aquiline Technology Growth Fund L.P. (“Aquiline Tech”) and Aquiline Armour Co-Invest L.P. (“Aquiline Armour”) (collectively the “Aquiline partnerships”). For further information regarding the Company’s Aquiline partnerships refer to Note 7(c), “Investments in investment affiliates,” included within the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 . The following table presents a reconciliation of the Company’s beginning and ending investments in investment affiliates for three and six months ended June 30, 2018 and 2017 : Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Investment affiliates, beginning of period $ 113,471 $ 94,697 $ 100,137 $ 100,431 Net capital contributions (distributions) 11,598 (786 ) 11,864 (11,708 ) Income from investment affiliates 2,178 9,466 15,246 14,654 Investment affiliates, end of period $ 127,247 $ 103,377 $ 127,247 $ 103,377 As at June 30, 2018 , the Company’s total unfunded investment commitment to the Aquiline partnerships was $95,788 ( December 31, 2017 : $125,996 ). The following table presents the Company’s investments in the Aquiline partnerships as at June 30, 2018 and December 31, 2017 : June 30, 2018 Investment at cost Voting ownership % Equity ownership % Carrying value Aquiline II $ 28,529 — % 8.1 % $ 49,248 Aquiline III 25,501 — % 9.0 % 59,900 Aquiline Tech 4,406 — % 10.6 % 4,400 Aquiline Armour 13,699 — % 15.2 % 13,699 Total investments in investment affiliates $ 72,135 $ 127,247 December 31, 2017 Investment at cost Voting ownership % Equity ownership % Carrying value Aquiline II $ 33,349 — % 8.1 % $ 51,914 Aquiline III 24,737 — % 9.0 % 44,733 Aquiline Tech 3,858 — % 10.6 % 3,490 Total investments in investment affiliates $ 61,944 $ 100,137 (d) Net investment income Net investment income was derived from the following sources: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Managed investments Fixed maturities and short-term investments $ 39,224 $ 31,212 $ 76,993 $ 62,883 Other investments 4,846 7,571 9,069 14,441 Cash and cash equivalents and restricted cash 1,744 716 2,883 1,326 Securities lending income 4 7 7 20 Total gross investment income 45,818 39,506 88,952 78,670 Investment expenses (3,066 ) (1,443 ) (6,409 ) (4,415 ) Total managed net investment income $ 42,752 $ 38,063 $ 82,543 $ 74,255 Non managed investments Fixed maturities and short-term investments $ 5,842 $ 4,500 $ 9,990 $ 7,560 Cash and cash equivalents and restricted cash 8,966 1,678 17,099 2,640 Total non-managed net investment income 14,808 6,178 27,089 10,200 Total net investment income $ 57,560 $ 44,241 $ 109,632 $ 84,455 Net investment income from other investments includes distributed and undistributed net income from certain fixed income investment funds. (e) Net realized (losses) gains and change in net unrealized (losses) gains on investments The following table sets forth an analysis of net realized (losses) gains and the change in net unrealized gains and losses on investments: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Managed investments Gross realized gains $ 3,048 $ 5,175 $ 9,878 $ 7,865 Gross realized (losses) (10,480 ) (2,906 ) (16,168 ) (8,488 ) Net realized (losses) gains on investments (7,432 ) 2,269 (6,290 ) (623 ) Change in net unrealized (losses) gains on investments (11,392 ) 15,942 (68,169 ) 30,291 Total net realized and change in net unrealized (losses) gains on managed investments $ (18,824 ) $ 18,211 $ (74,459 ) $ 29,668 Non-managed investments Gross realized gains $ 175 $ 5 $ 1,410 $ 1,733 Gross realized (losses) (137 ) — (314 ) — Net realized gains on investments 38 5 1,096 1,733 Change in net unrealized gains (losses) on investments 662 379 58 (622 ) Total net realized and change in net unrealized gains on non-managed investments 700 384 1,154 1,111 Total net realized and change in net unrealized (losses) gains on total investments $ (18,124 ) $ 18,595 $ (73,305 ) $ 30,779 (f) Pledged investments and cash As at June 30, 2018 , the Company had $6,310,851 ( December 31, 2017 : $5,853,744 ) of cash and cash equivalents, restricted cash, short-term investments and fixed maturity investments that were pledged during the normal course of business. Of those, $6,282,368 were held in trust ( December 31, 2017 : $5,789,081 ). Pledged assets are generally for the benefit of the Company’s cedants and policyholders, to support AlphaCat’s fully collateralized reinsurance transactions, as collateral for derivative instruments and to facilitate the accreditation of Validus Reinsurance, Ltd. (“Validus Re”), Validus Reinsurance (Switzerland) Ltd. (“Validus Re Swiss”) and Lloyd’s Syndicate 1183 (the “Talbot Syndicate”) as alien (re)insurers by certain regulators. In addition, the Company has pledged cash and investments as collateral under the Company’s credit facilities in the amount of $539,627 ( December 31, 2017 : $576,864 ). For further details on the credit facilities, refer to Note 13 “Debt and financing arrangements.”

Fair value measurements

Fair value measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair value measurements	Fair value measurements (a) Classification within the fair value hierarchy Fair value is defined as the price to sell an asset or transfer a liability in an orderly transaction between market participants. Under U.S. GAAP, a company must determine the appropriate level in the fair value hierarchy for each fair value measurement. The fair value hierarchy prioritizes the inputs, which refer broadly to assumptions market participants would use in pricing an asset or liability, into three levels. It gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The level in the fair value hierarchy within which a fair value measurement in its entirety falls is determined based on the lowest level input that is significant to the fair value measurement in its entirety. The three levels of the fair value hierarchy are described below: Level 1 - Fair values are measured based on unadjusted quoted prices in active markets for identical assets or liabilities that we have the ability to access. Level 2 - Fair values are measured based on quoted prices in active markets for similar assets or liabilities, quoted prices for identical assets or liabilities in inactive markets, or for which significant inputs are observable (e.g., interest rates, yield curves, prepayment speeds, default rates, loss severities, etc.) or can be corroborated by observable market data. Level 3 - Fair values are measured based on unobservable inputs that reflect the Company’s own judgments about assumptions where there is little, if any, market activity for that asset or liability that market participants might use. The availability of observable inputs can vary from financial instrument to financial instrument and is affected by a wide variety of factors including, for example, the type of financial instrument, whether the financial instrument is new and not yet established in the marketplace, and other characteristics particular to the instrument. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires significantly more judgment. Accordingly, the degree of judgment exercised by management in determining fair value is greatest for instruments categorized in Level 3. In periods of market dislocation, the observability of prices and inputs may be reduced for many instruments. This may lead the Company to change the selection of the valuation technique (for example, from market to cash flow approach) or to use multiple valuation techniques to estimate the fair value of a financial instrument. These circumstances could cause an instrument to be reclassified between levels within the fair value hierarchy. At June 30, 2018 , the Company’s investments were allocated between Levels 1, 2 and 3 as follows: Level 1 Level 2 Level 3 Fair value based on NAV practical expedient (a) Total Managed investments U.S. government and government agency $ — $ 604,392 $ — $ — $ 604,392 Non-U.S. government and government agency — 282,263 — — 282,263 U.S. states, municipalities and political subdivisions — 189,437 — — 189,437 Agency residential mortgage-backed securities — 929,859 — — 929,859 Non-agency residential mortgage-backed securities — 47,600 — — 47,600 U.S. corporate — 1,436,885 — — 1,436,885 Non-U.S. corporate — 403,385 — — 403,385 Bank loans — 245,476 225,736 — 471,212 Asset-backed securities — 613,169 101,265 — 714,434 Commercial mortgage-backed securities — 301,544 — — 301,544 Total fixed maturities — 5,054,010 327,001 — 5,381,011 Short-term investments 187,231 30,804 — — 218,035 Other investments Hedge funds — — — 15,888 15,888 Private equity investments — — — 79,185 79,185 Fixed income investment funds — 9,576 18,807 181,120 209,503 Overseas deposits — — — 61,608 61,608 Total other investments — 9,576 18,807 337,801 366,184 Investments in investment affiliates (b) — — — — 127,247 Total managed investments $ 187,231 $ 5,094,390 $ 345,808 $ 337,801 $ 6,092,477 Non-managed investments Catastrophe bonds $ — $ 127,380 $ 51,562 $ — $ 178,942 Short-term investments 3,510,859 — — — 3,510,859 Total non-managed investments 3,510,859 127,380 51,562 — 3,689,801 Total investments $ 3,698,090 $ 5,221,770 $ 397,370 $ 337,801 $ 9,782,278 (a) In accordance with ASC Topic 820 “Fair Value Measurements,” investments measured at fair value using the net asset value (“NAV”) per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. (b) In accordance with ASC Topic 825 “Financial Instruments,” the Company’s investments in investment affiliates have not been classified in the fair value hierarchy. At December 31, 2017 , the Company’s investments were allocated between Levels 1, 2 and 3 as follows: Level 1 Level 2 Level 3 Fair value based on NAV practical expedient (a) Total Managed investments U.S. government and government agency $ — $ 727,397 $ — $ — $ 727,397 Non-U.S. government and government agency — 312,239 — — 312,239 U.S. states, municipalities and political subdivisions — 201,303 — — 201,303 Agency residential mortgage-backed securities — 978,049 — — 978,049 Non-agency residential mortgage-backed securities — 40,373 — — 40,373 U.S. corporate — 1,533,395 — — 1,533,395 Non-U.S. corporate — 422,249 — — 422,249 Bank loans — 232,886 210,065 — 442,951 Asset-backed securities — 554,490 103,813 — 658,303 Commercial mortgage-backed securities — 312,395 — — 312,395 Total fixed maturities — 5,314,776 313,878 — 5,628,654 Short-term investments 198,054 31,957 — — 230,011 Other investments Hedge funds — — — 15,774 15,774 Private equity investments — — — 78,407 78,407 Fixed income investment funds — 13,351 17,404 173,671 204,426 Overseas deposits — — — 56,611 56,611 Total other investments — 13,351 17,404 324,463 355,218 Investments in investment affiliates (b) — — — — 100,137 Total managed investments $ 198,054 $ 5,360,084 $ 331,282 $ 324,463 $ 6,314,020 Non-managed investments Catastrophe bonds $ — $ 152,233 $ 77,461 $ — $ 229,694 Short-term investments 3,151,746 — — — 3,151,746 Total non-managed investments 3,151,746 152,233 77,461 — 3,381,440 Total investments $ 3,349,800 $ 5,512,317 $ 408,743 $ 324,463 $ 9,695,460 (a) In accordance with ASC Topic 820 “Fair Value Measurements,” investments measured at fair value using the net asset value (“NAV”) per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. (b) In accordance with ASC Topic 825 “Financial Instruments,” the Company’s investments in investment affiliates have not been classified in the fair value hierarchy. At June 30, 2018 , managed Level 3 investments totaled $345,808 ( December 31, 2017 : $331,282 ), representing 5.7% ( December 31, 2017 : 5.2% ) of total managed investments. (b) Valuation techniques There have been no material changes in the Company’s valuation techniques during the periods presented in these Consolidated Financial Statements. The following methods and assumptions were used in estimating the fair value of each class of financial instrument recorded in the Consolidated Balance Sheets. Fixed maturity investments In general, valuation of the Company’s fixed maturity investment portfolio is provided by pricing services, such as index providers and pricing vendors, as well as broker quotations. The pricing vendors provide valuations for a high volume of liquid securities that are actively traded. For securities that do not trade on an exchange, the pricing services generally utilize market data and other observable inputs in matrix pricing models to determine month end prices. Prices are generally verified using third party data. Index providers generally utilize centralized trade reporting networks, available market makers and statistical techniques. In general, broker-dealers value securities through their trading desks based on observable inputs. The methodologies include mapping securities based on trade data, bids or offers, observed spreads, and performance on newly issued securities. Broker-dealers also determine valuations by observing secondary trading of similar securities. Prices obtained from broker quotations are considered non-binding, however they are based on observable inputs and by observing secondary trading of similar securities obtained from active, non-distressed markets. The Company considers these valuations to be Level 2 inputs as they are corroborated with other market observable inputs. The techniques generally used to determine the fair value of the Company’s fixed maturity investments are detailed below by asset class. U.S. government and government agency U.S. government and government agency securities consist primarily of debt securities issued by the U.S. Treasury and mortgage pass-through agencies such as the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation and the Government National Mortgage Association. Fixed maturity investments included in U.S. government and government agency securities are primarily priced by pricing services. When evaluating these securities, the pricing services gather information from market sources and integrate other observations from markets and sector news. Evaluations are updated by obtaining broker dealer quotes and other market information including actual trade volumes, when available. The fair value of each security is individually computed using analytical models which incorporate option adjusted spreads and other daily interest rate data. As the significant inputs used to price these securities are observable, the fair values of these investments are classified as Level 2. Non-U.S. government and government agency Non-U.S. government and government agency securities consist of debt securities issued by non-U.S. governments and their agencies along with supranational organizations (also known as sovereign debt securities). Securities held in these sectors are primarily priced by pricing services that employ proprietary discounted cash flow models to value the securities. Key quantitative inputs for these models are daily observed benchmark curves for treasury, swap and high issuance credits. The pricing services then apply a credit spread for each security which is developed by in-depth and real time market analysis. For securities in which trade volume is low, the pricing services utilize data from more frequently traded securities with similar attributes. These models may also be supplemented by daily market and credit research for international markets. As the significant inputs used to price these securities are observable, the fair values of these investments are classified as Level 2. U.S. states, municipalities and political subdivisions The Company’s U.S. states, municipalities and political subdivisions portfolio contains debt securities issued by U.S. domiciled state and municipal entities. These securities are generally priced by independent pricing services using the techniques described for U.S. government and government agency securities described above. As the significant inputs used to price these securities are observable, the fair values of these investments are classified as Level 2. Agency residential mortgage-backed securities The Company’s agency residential mortgage-backed investments are primarily priced by pricing services using a mortgage pool specific model which utilizes daily inputs from the active to be announced market which is very liquid, as well as the U.S. treasury market. The model also utilizes additional information, such as the weighted average maturity, weighted average coupon and other available pool level data which is provided by the sponsoring agency. Valuations are also corroborated with daily active market quotes. As the significant inputs used to price these securities are observable, the fair values of these investments are classified as Level 2. Non-agency residential mortgage-backed securities The Company’s non-agency mortgage-backed investments include non-agency prime residential mortgage-backed fixed maturity investments. The Company holds no sub-prime fixed maturity investments in its fixed maturity investments portfolio. Securities held in these sectors are primarily priced by pricing services using an option adjusted spread model or other relevant models, which principally utilize inputs including benchmark yields, available trade information or broker quotes, and issuer spreads. The pricing services also review collateral prepayment speeds, loss severity and delinquencies among other collateral performance indicators for the securities valuation, when applicable. As the significant inputs used to price these securities are observable, the fair values of these investments are classified as Level 2. U.S. corporate U.S. corporate debt securities consist primarily of investment-grade debt of a wide variety of U.S. corporate issuers and industries. The Company’s corporate fixed maturity investments are primarily priced by pricing services. When evaluating these securities, the pricing services gather information from market sources regarding the issuer of the security and obtain credit data, as well as other observations, from markets and sector news. Evaluations are updated by obtaining broker dealer quotes and other market information including actual trade volumes, when available. The pricing services also consider the specific terms and conditions of the securities, including any specific features which may influence risk. In certain instances, securities are individually evaluated using a spread which is added to the U.S. treasury curve or a security specific swap curve as appropriate. As the significant inputs used to price these securities are observable, the fair values of these investments are classified as Level 2. Non-U.S. corporate Non-U.S. corporate debt securities consist primarily of investment-grade debt of a wide variety of non-U.S. corporate issuers and industries. The Company’s non-U.S. corporate fixed maturity investments are primarily priced by pricing services. When evaluating these securities, the pricing services gather information from market sources regarding the issuer of the security and obtain credit data, as well as other observations, from markets and sector news. Evaluations are updated by obtaining broker dealer quotes and other market information including actual trade volumes, when available. The pricing services also consider the specific terms and conditions of the securities, including any specific features which may influence risk. As the significant inputs used to price these securities are observable, the fair values of these investments are classified as Level 2. Bank loans The Company’s bank loan investments consist primarily of below-investment-grade debt of a wide variety of corporate issuers and industries. The Company’s bank loans are primarily priced by pricing services. When evaluating these securities, the pricing services gather information from market sources regarding the issuer of the security and obtain credit data, as well as other observations, from markets and sector news. Evaluations are updated by obtaining broker dealer quotes and other market information including actual trade volumes, when available. The pricing services also consider the specific terms and conditions of the securities, including any specific features which may influence risk. As the significant inputs used to price these securities are observable, the fair values of these investments are classified as Level 2. Also, included in the bank loan portfolio is a collection of loan participations held through an intermediary. A third party pricing service provides monthly valuation reports for each loan and participation using a combination of quotations from loan pricing services, leveraged loan indices or market price quotes obtained directly from the intermediary. Significant unobservable inputs used to price these securities include credit spreads and default rates; therefore, the fair values of these investments are classified as Level 3. Asset-backed securities Asset backed securities include mostly investment-grade debt securities backed by pools of loans with a variety of underlying collateral, including automobile loan receivables, student loans, credit card receivables, and collateralized loan obligations originated by a variety of financial institutions. Securities held in these sectors are primarily priced by pricing services. The pricing services apply dealer quotes and other available trade information such as bids and offers, prepayment speeds which may be adjusted for the underlying collateral or current price data, the U.S. treasury curve and swap curve as well as cash settlement. The pricing services determine the expected cash flows for each security held in this sector using historical prepayment and default projections for the underlying collateral and current market data. In addition, a spread is applied to the relevant benchmark and used to discount the cash flows noted above to determine the fair values of the securities held in this sector. As the significant inputs used to price these securities are observable, the fair value of these investments are classified as Level 2. Where pricing is unavailable from pricing services, we obtain non-binding quotes from broker-dealers. This is generally the case when there is a low volume of trading activity and current transactions are not orderly. Broker-dealer quotes for which significant observable inputs are unable to be corroborated with market observable information are classified as Level 3. Commercial mortgage-backed securities Commercial mortgage backed securities are investment-grade debt primarily priced by pricing services. The pricing services apply dealer quotes and other available trade information such as bids and offers, prepayment speeds which may be adjusted for the underlying collateral or current price data, the U.S. treasury curve and swap curve as well as cash settlement. The pricing services determine the expected cash flows for each security held in this sector using historical prepayment and default projections for the underlying collateral and current market data. In addition, a spread is applied to the relevant benchmark and used to discount the cash flows noted above to determine the fair value of the securities held in this sector. As the significant inputs used to price these securities are observable, the fair values of these investments are classified as Level 2. Catastrophe bonds Catastrophe bonds are priced based on broker or underwriter bid indications. Level 2 catastrophe bonds are those traded over-the-counter; catastrophe bonds available only via private issuances are classified as Level 3. Short-term investments Short-term investments consist primarily of highly liquid securities, all with maturities of less than one year from the date of purchase. The fair value of the portfolio is generally determined using amortized cost which approximates fair value. As the highly liquid money market-type funds are actively traded, the fair value of these investments are classified as Level 1. To the extent that the remaining securities are not actively traded due to their approaching maturity, the fair values of these investments are classified as Level 2. Other investments Hedge funds The hedge fund’s administrator provides quarterly NAVs with a three month delay in valuation. The fair value of this investment is measured using the NAV practical expedient and therefore has not been categorized within the fair value hierarchy. Private equity investments The private equity funds provide quarterly or semi-annual partnership capital statements with a three or six month delay which are used as a basis for valuation. These private equity investments vary in investment strategies and are not actively traded in any open markets. The fair value of these investments are measured using the NAV practical expedient and therefore have not been categorized within the fair value hierarchy. Fixed income investment funds The Company’s investment funds classified as Level 2 consist of a pooled investment fund. The pooled investment is invested in fixed income securities with high credit ratings and is available only to Lloyd’s Trust Fund participants. The fair value of units in the investment fund is based on the NAV of the fund, which is traded on a daily basis. Included in investment funds is a residual equity tranche of a structured credit fund valued using a dynamic yield that calculates an income accrual based on an underlying valuation model with a typical cash flow waterfall structure. Significant unobservable inputs used to price this fund include default rates and prepayment rates; therefore, the fair value of the investment fund is classified as Level 3. The fair value of the Company’s remaining investment funds is based on the NAV of the fund as reported by the independent fund administrator. The fund’s administrators provide a monthly reported NAV with a one or three month delay in their valuation. The fair value of these investments is measured using the NAV practical expedient and therefore it has not been categorized within the fair value hierarchy. None of these investments are probable of being sold at amounts different than their NAVs. Overseas deposits The Company’s share of a portfolio of Lloyd’s overseas deposits is managed centrally by Lloyd’s and invested according to local regulatory requirements. The composition of the portfolio varies and the deposits are made across the market. The fair values of the deposits are based on the portfolio level reporting that is provided by Lloyd’s. The fair values of these investments are measured using the NAV practical expedient and therefore have not been categorized within the fair value hierarchy. (c) Level 3 investments The following table presents a reconciliation of the beginning and ending balances for all investments measured at fair value on a recurring basis using Level 3 inputs during the three and six months ended June 30, 2018 and 2017 : Three Months Ended June 30, 2018 Bank Loans Catastrophe Bonds Fixed Income Investment Funds Asset Backed Securities Total Level 3 investments, beginning of period $ 227,503 $ 65,697 $ 17,933 $ 101,816 $ 412,949 Purchases 14,422 — 874 — 15,296 Sales — — — (70 ) (70 ) Settlements (14,698 ) (15,001 ) — — (29,699 ) Change in net unrealized (losses) gains (1,491 ) 866 — (481 ) (1,106 ) Level 3 investments, end of period $ 225,736 $ 51,562 $ 18,807 $ 101,265 $ 397,370 Three Months Ended June 30, 2017 Bank Loans Catastrophe Bonds Fixed Income Investment Funds Asset Backed Securities Total Level 3 investments, beginning of period $ 236,694 $ 72,676 $ 12,560 $ 23,882 $ 345,812 Purchases 16,757 5,000 3,432 11,053 36,242 Sales — — — (53 ) (53 ) Settlements (28,893 ) (10,216 ) 408 — (38,701 ) Realized gains — 216 — — 216 Change in net unrealized (losses) gains (386 ) 349 — 1,039 1,002 Level 3 investments, end of period $ 224,172 $ 68,025 $ 16,400 $ 35,921 $ 344,518 Six Months Ended June 30, 2018 Bank Loans Catastrophe Bonds Fixed Income Investment Funds Asset Backed Securities Total Level 3 investments, beginning of period $ 210,065 $ 77,461 $ 17,404 $ 103,813 $ 408,743 Purchases 45,207 18,825 1,403 — 65,435 Sales — — — (140 ) (140 ) Settlements (28,540 ) (46,485 ) — — (75,025 ) Realized gains — 1,235 — — 1,235 Change in net unrealized (losses) gains (996 ) 526 — (2,408 ) (2,878 ) Level 3 investments, end of period $ 225,736 $ 51,562 $ 18,807 $ 101,265 $ 397,370 Six Months Ended June 30, 2017 Bank Loans Catastrophe Bonds Fixed Income Investment Funds Asset Backed Securities Total Level 3 investments, beginning of period $ 246,496 $ 48,375 $ 12,168 $ 23,931 $ 330,970 Purchases 39,933 66,091 3,432 11,053 120,509 Sales — — — (53 ) (53 ) Settlements (62,003 ) (48,996 ) 800 — (110,199 ) Realized gains — 3,350 — — 3,350 Change in net unrealized (losses) gains (254 ) (795 ) — 990 (59 ) Level 3 investments, end of period $ 224,172 $ 68,025 $ 16,400 $ 35,921 $ 344,518 There were no transfers into or out of Level 3 during the three and six months ended June 30, 2018 or 2017 . (d) Financial instruments not carried at fair value ASC Topic 825 “Financial Instruments” is also applicable to disclosures of financial instruments not carried at fair value, except for certain financial instruments, including insurance contracts and investments in affiliates. The carrying values of accrued investment income, other assets, net payable for investments purchased and accounts payable and accrued expenses approximated their fair values at June 30, 2018 , due to their respective short maturities. As these financial instruments are not actively traded, their respective fair values are classified within Level 2.

Variable interest entities

Variable interest entities	6 Months Ended
	Jun. 30, 2018
Variable Interest Entities Disclosure [Abstract]
Variable interest entities	Variable interest entities The Company consolidates all VIEs in which it is considered to be the primary beneficiary. The Company’s VIEs are primarily entities in the AlphaCat segment. (a) Consolidated VIEs AlphaCat sidecars Beginning on May 25, 2011, the Company joined with other investors in capitalizing a series of reinsurance and investment entities, referred to as “sidecars,” for the purpose of investing in collateralized reinsurance and retrocessional contracts. Certain of these sidecars deployed their capital through transactions entered into by AlphaCat Reinsurance Ltd. (“AlphaCat Re”). Each of these entities returns capital once the risk period expires and all losses have been paid out. The AlphaCat sidecars are VIEs and are consolidated by the Company. The Company’s maximum exposure to any of these sidecars is the amount of capital invested at any given time. AlphaCat ILS funds The AlphaCat ILS funds received third party subscriptions beginning on December 17, 2012. The Company and third party investors invest in the AlphaCat ILS funds for the purpose of investing in instruments with returns linked to property catastrophe reinsurance, retrocession and ILS contracts. The AlphaCat ILS funds have varying risk profiles and are categorized by the maximum permitted portfolio expected loss of the fund. The permitted portfolio expected loss represents the average annual loss over the set of simulation scenarios divided by the total limit. Lower risk ILS funds are defined as having a maximum permitted portfolio expected loss of less than 7%, whereas higher risk ILS funds have a maximum permitted portfolio expected loss of 7% or greater. The AlphaCat ILS funds primarily deploy their capital through transactions entered into by AlphaCat Re and AlphaCat Master Fund Ltd. (“AlphaCat Master Fund”). All of the AlphaCat ILS funds are VIEs and were consolidated by the Company through May 31, 2017. However, on June 1, 2017, the Company redeemed its investment in one of the lower risk AlphaCat ILS funds. As a result, the Company was no longer deemed to be the primary beneficiary and therefore this fund was deconsolidated effective June 1, 2017. The Company’s maximum exposure to any of the AlphaCat ILS funds is the amount of capital invested at any given time and any remaining capital commitments. AlphaCat Re and AlphaCat Master Fund The Company utilizes AlphaCat Re and AlphaCat Master Fund (collectively the “Master Funds”), both market facing entities, for the purpose of writing collateralized reinsurance and investing in capital markets products, respectively, on behalf of certain entities within the Asset Management segment and direct third party investors. AlphaCat Re enters into transactions on behalf of the AlphaCat sidecars and ILS funds (collectively the “Feeder Funds”) and direct third party investors, whereas AlphaCat Master Fund only enters into transactions on behalf of certain AlphaCat ILS funds. All of the risks and rewards of the underlying transactions are allocated to the Feeder Funds and direct third party investors using variable funding notes. The Master Funds are VIEs and are consolidated by the Company. Notes Payable to AlphaCat Investors The Master Funds issue variable funding notes to the Feeder Funds, and direct to third party investors, in order to write collateralized reinsurance and invest in capital markets products on their behalf. The Company’s investments in the Feeder Funds, together with investments made by third parties in the Feeder Funds and on a direct basis, are provided as consideration for the notes to the Master Funds. The duration of the underlying collateralized reinsurance contracts and capital market products is typically twelve months ; however, the variable funding notes do not have a stated maturity date since repayment is dependent on the settlement and income or loss of the underlying transactions. Therefore, the notes are redeemed as the underlying transactions are settled. The income or loss generated by the underlying transactions is then transferred to the Feeder Funds and direct third party investors via the variable funding notes. Any notes issued by the Master Funds to the consolidated Feeder Funds are eliminated on consolidation and only variable funding notes issued by AlphaCat Re directly to third party investors and non-consolidated Feeder Funds remain on the Consolidated Balance Sheets as notes payable to AlphaCat investors with the related income or loss included in the Consolidated Statements of (Loss) Income and Comprehensive (Loss) Income as (income) attributable to AlphaCat investors. To the extent that the income has not been returned to the investors, it is included in accounts payable and accrued expenses in the Consolidated Balance Sheets. One of the AlphaCat ILS funds (the “Fund”) issued both common shares and structured notes to the Company and third party investors in order to capitalize the fund. The Fund deploys its capital through AlphaCat Re; therefore, the structured notes do not have a stated maturity date since repayment is dependent on the settlement and income or loss of the variable funding notes with AlphaCat Re. The structured notes rank senior to the common shares of the Fund and earn an interest rate of 6.5% ( 2017 : 7% ) per annum, payable on a cumulative basis in arrears. As the Fund is consolidated by the Company, the structured notes issued to the Company are eliminated on consolidation and only the structured notes issued to third party investors remain on the Consolidated Balance Sheets as notes payable to AlphaCat investors, with any related interest included in the Consolidated Statements of (Loss) Income and Comprehensive (Loss) Income as (income) attributable to AlphaCat investors. To the extent that the accrued interest on the structured notes has not been returned to the investors, it is included in accounts payable and accrued expenses in the Consolidated Balance Sheets. The following tables present reconciliations of the beginning and ending notes payable to AlphaCat investors during the three and six months ended June 30, 2018 and 2017 : Three Months Ended June 30, 2018 Variable Funding Notes Structured Notes Total Notes payable to AlphaCat investors, beginning of period $ 916,022 $ 352,172 $ 1,268,194 Issuance of notes payable to AlphaCat investors 305,039 280 305,319 Redemption of notes payable to AlphaCat investors (362,565 ) — (362,565 ) Foreign exchange gains (4,277 ) — (4,277 ) Notes payable to AlphaCat investors, end of period $ 854,219 $ 352,452 $ 1,206,671 Three Months Ended June 30, 2017 Variable Funding Notes Structured Notes Total Notes payable to AlphaCat investors, beginning of period $ 343,256 $ 103,320 $ 446,576 Notes payable to AlphaCat investors recognized on deconsolidation of AlphaCat ILS fund 423,269 — 423,269 Issuance of notes payable to AlphaCat investors 267,867 68,880 336,747 Redemption of notes payable to AlphaCat investors (140,150 ) — (140,150 ) Foreign exchange gains (283 ) — (283 ) Notes payable to AlphaCat investors, end of period $ 893,959 $ 172,200 $ 1,066,159 Six Months Ended June 30, 2018 Variable Funding Notes Structured Notes Total Notes payable to AlphaCat investors, beginning of period $ 936,164 $ 172,200 $ 1,108,364 Issuance of notes payable to AlphaCat investors 811,579 180,252 991,831 Redemption of notes payable to AlphaCat investors (893,111 ) — (893,111 ) Foreign exchange gains (413 ) — (413 ) Notes payable to AlphaCat investors, end of period $ 854,219 $ 352,452 $ 1,206,671 Six Months Ended June 30, 2017 Variable Funding Notes Structured Notes Total Notes payable to AlphaCat investors, beginning of period $ 278,202 $ — $ 278,202 Notes payable to AlphaCat investors recognized on deconsolidation of AlphaCat ILS fund 423,269 — 423,269 Issuance of notes payable to AlphaCat investors 541,877 172,200 714,077 Redemption of notes payable to AlphaCat investors (349,106 ) — (349,106 ) Foreign exchange gains (283 ) — (283 ) Notes payable to AlphaCat investors, end of period $ 893,959 $ 172,200 $ 1,066,159 The income attributable to AlphaCat investors for the three and six months ended June 30, 2018 was $29,849 and $40,711 , respectively ( 2017 : $11,830 and $19,333 ). As at June 30, 2018 , amounts due to AlphaCat investors totaling $66,259 ( December 31, 2017 : $18,054 ) were included in accounts payable and accrued expenses. BetaCat ILS funds The BetaCat ILS funds follow a passive buy-and-hold investment strategy, investing exclusively in catastrophe bonds (principal-at-risk variable rate notes and other event-linked securities, referred to collectively as “Cat Bonds”) focused on property and casualty risks and issued under Rule 144A of the Securities Act of 1933, as amended. Two of the three BetaCat ILS funds are VIEs, one of which is consolidated by the Company. The remaining fund is a VOE and is consolidated by the Company as it owns all of the fund’s voting equity interests. The Company’s maximum exposure to any of the funds is the amount of capital invested at any given time. The following table presents the total assets and total liabilities of the Company’s consolidated VIEs, excluding intercompany eliminations, as at June 30, 2018 and December 31, 2017 : June 30, 2018 December 31, 2017 Total Assets Total Liabilities Total Assets Total Liabilities AlphaCat sidecars $ 15,647 $ 3,102 $ 25,975 $ 3,267 AlphaCat ILS funds - Lower Risk 1,205,476 86,339 1,107,503 259,630 AlphaCat ILS funds - Higher Risk 1,162,492 383,231 1,310,071 912,341 AlphaCat Re and AlphaCat Master Fund 3,830,442 3,830,272 3,398,082 3,397,912 BetaCat ILS funds 89,161 210 77,221 261 Assets of consolidated VIEs can only be used to settle obligations and liabilities of the consolidated VIEs and do not have recourse to the general credit of the Company. Investments held by these entities are presented separately in Note 4 , “Investments,” as non-managed investments. (b) Non-Consolidated VIEs The Company invests in private equity and other investment vehicles as part of the Company’s investment portfolio. The activities of these VIEs are generally limited to holding investments and the Company’s involvement in these entities is passive in nature. The Company’s maximum exposure to the VIEs is the amount of capital invested at any given time, and the Company does not have the power to direct the activities which most significantly impact the VIEs economic performance. The Company is therefore not the primary beneficiary of these VIEs. Refer to Note 4 , “Investments,” for further details.

Noncontrolling interest

Noncontrolling interest	6 Months Ended
	Jun. 30, 2018
Noncontrolling Interest [Abstract]
Noncontrolling interest	Noncontrolling interests Investors in certain of the AlphaCat and BetaCat ILS funds have rights that enable them, subject to certain limitations, to redeem their shares. Such investments held by third parties are therefore recorded in the Company’s Consolidated Balance Sheets as redeemable noncontrolling interests, a mezzanine item between liabilities and shareholders’ equity. If and when a redemption notice is received, the fair value of the redemption is reclassified to accounts payable and accrued expenses. The AlphaCat sidecars and one of the AlphaCat ILS funds have no shareholder redemption rights. Therefore, the third party equity is recorded in the Company’s Consolidated Balance Sheets as noncontrolling interests. The following tables present a reconciliation of the beginning and ending balances of redeemable noncontrolling interests and noncontrolling interests for the three and six months ended June 30, 2018 and 2017 : Redeemable Noncontrolling Interests Total Three Months Ended June 30, Three Months Ended June 30, Three Months Ended June 30, 2018 2017 2018 2017 2018 2017 Balance, beginning of period $ 1,423,110 $ 1,657,630 $ 334,357 $ 330,597 $ 1,757,467 $ 1,988,227 Issuance of shares 81,250 106,501 40,600 103,320 121,850 209,821 Adjustment to noncontrolling interests as a result of deconsolidation — (459,021 ) — — — (459,021 ) Income attributable to noncontrolling interests 19,255 28,555 16,256 15,095 35,511 43,650 Redemption of shares / Distributions (133,382 ) (82,005 ) (19,956 ) (33,354 ) (153,338 ) (115,359 ) Balance, end of period $ 1,390,233 $ 1,251,660 $ 371,257 $ 415,658 $ 1,761,490 $ 1,667,318 Redeemable Noncontrolling Interests Total Six Months Ended June 30, Six Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 2018 2017 Balance, beginning of period $ 1,004,094 $ 1,528,001 $ 16,718 $ 165,977 $ 1,020,812 $ 1,693,978 Issuance of shares 466,550 210,200 321,900 258,300 788,450 468,500 Adjustment to noncontrolling interests as a result of deconsolidation — (459,021 ) — — — (459,021 ) Income attributable to noncontrolling interests 47,628 54,485 52,595 31,737 100,223 86,222 Redemption of shares / Distributions (128,039 ) (82,005 ) (19,956 ) (40,356 ) (147,995 ) (122,361 ) Balance, end of period $ 1,390,233 $ 1,251,660 $ 371,257 $ 415,658 $ 1,761,490 $ 1,667,318 As at June 30, 2018 , redemptions payable of $80,315 ( December 31, 2017 : $180,104 ) relating to redeemable noncontrolling interests were included within accounts payable and accrued expenses in the Company’s Consolidated Balance Sheets.

Derivative instruments

Derivative instruments	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative instruments	Derivative instruments The Company enters into various derivative instruments in the form of foreign currency forward exchange contracts, interest rate swap contracts and weather derivative instruments. These derivative instruments are used to manage exposures to currency and interest rate risks, to enhance the efficiency of the Company’s investment portfolio and to provide protection against cedants’ financial exposure to variability in weather patterns. All of the Company’s outstanding derivative financial instruments are recognized in the Consolidated Balance Sheets at their fair values. The effect on earnings from recognizing the fair values of these derivative financial instruments depends on each instrument’s intended use, hedge designation, and effectiveness in offsetting the exposure it is intended to hedge. (a) Derivatives not designated as hedging instruments The following tables summarize information on the classification and amount of the fair value of derivatives not designated as hedging instruments within the Company’s Consolidated Balance Sheets as at June 30, 2018 and December 31, 2017 : June 30, 2018 December 31, 2017 Derivatives not designated as hedging instruments Notional Exposure Asset Derivative at Fair Value (a) Liability Derivative at Fair Value (a) Notional Exposure Asset Derivative at Fair Value (a) Liability Derivative at Fair Value (a) Foreign currency forward contracts $ 190,952 $ 3,880 $ 3,310 $ 283,765 $ 1,147 $ 906 Interest rate swap contracts $ 200,000 $ 10,306 $ — $ 200,000 $ 1,589 $ — Weather derivative contracts $ 4,825 $ 8,380 $ — $ 4,825 $ 853 $ — (a) Asset and liability derivative positions are classified within other assets and accounts payable and accrued expenses, respectively, within the Company’s Consolidated Balance Sheets. The foreign currency forward contracts and interest rate swap contracts are valued on the basis of standard industry valuation models. The inputs to these models are based on observable market inputs, and as such the fair values of these contracts are classified as Level 2. The weather derivative contracts are valued on the basis of modeled and other information provided by Validus’ counterparties. Validus reviews this information, which represents Level 3 inputs, as it is ultimately management’s responsibility to ensure that the fair values reflected in the Company’s financial statements are appropriate. The following table summarizes information on the classification and net impact on earnings recognized in the Company’s Consolidated Statements of (Loss) Income and Comprehensive (Loss) Income relating to derivatives that were not designated as hedging instruments during the three and six months ended June 30, 2018 and 2017 : Derivatives not designated as hedging instruments Classification of gains recognized in earnings Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Foreign currency forward contracts Foreign exchange (losses) gains $ 4,843 $ (6,525 ) $ (358 ) $ (6,072 ) Foreign currency forward contracts Other insurance related income and other income $ — $ (874 ) $ — $ (979 ) Interest rate swap contracts Net realized gains on investments $ 2,123 $ (319 ) $ 8,067 $ (319 ) Weather derivative contracts Other insurance related income and other income $ (17,910 ) $ — $ 8,863 $ — (b) Derivatives designated as hedging instruments Derivative instruments designated as cash flow hedges During 2012 and 2013, the Company entered into several swap agreements with third parties in order to convert the floating interest rates associated with its Junior Subordinated Deferrable Debentures into fixed rates. See Note 13 , “ Debt and financing arrangements, ” for further details. The Company also designates certain foreign exchange contracts as cash flow hedges of anticipated foreign currency-denominated sales or purchases. The following table summarizes information on the classification and amount of the fair value of derivatives designated as hedging instruments on the Consolidated Balance Sheets as at June 30, 2018 and December 31, 2017 : June 30, 2018 December 31, 2017 Derivatives designated as hedging instruments Notional Exposure Asset Derivative at Fair Value (a) Liability Derivative at Fair Value (a) Notional Exposure Asset Derivative at Fair Value (a) Liability Derivative at Fair Value (a) Interest rate swap contracts $ 552,263 $ 28,982 $ 2,627 $ 552,263 $ 9,806 $ 18,840 Foreign currency forward contracts $ 64,405 $ — $ 546 $ 96,293 $ 1,891 $ — (a) Asset and liability derivative positions are classified within other assets and accounts payable and accrued expenses, respectively, within the Company’s Consolidated Balance Sheets. The interest rate swap contracts and foreign currency forward contracts are valued on the basis of Level 2 inputs. The following tables provide the total impact on other comprehensive income and earnings relating to the derivative instruments formally designated as cash flow hedges for the three and six months ended June 30, 2018 and 2017 : Three Months Ended June 30, Six Months Ended June 30, Interest rate swap contracts 2018 2017 2018 2017 Amount recognized in other comprehensive income $ 7,200 $ (144 ) $ 33,043 $ (46 ) Amount reclassified to finance expenses $ 698 $ — $ 2,041 $ — Three Months Ended June 30, Six Months Ended June 30, Foreign currency forward contracts 2018 2017 2018 2017 Amount recognized in other comprehensive income $ (4,165 ) $ — $ (1,245 ) $ — Amount reclassified to general and administrative expenses $ (884 ) $ — $ (1,192 ) $ — (c) Balance sheet offsetting There was no balance sheet offsetting activity as at June 30, 2018 or December 31, 2017 . The Company provides investments as collateral for interest rate swap contracts and weather derivative contracts. The Company does not provide collateral or financial instruments as security for foreign currency forward contracts. Our derivative instruments are generally traded under International Swaps and Derivatives Association master agreements, which establish terms that apply to all transactions. On a periodic basis, the amounts receivable from or payable to the counterparties are settled in cash. The Company has not elected to settle multiple transactions with an individual counterparty on a net basis.

Reserve for losses and loss exp

Reserve for losses and loss expenses	6 Months Ended
	Jun. 30, 2018
Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract]
Reserve for losses and loss expenses	Reserve for losses and loss expenses The following table summarizes the Company’s reserve for losses and loss expenses as at June 30, 2018 and December 31, 2017 : June 30, 2018 December 31, 2017 Case reserves $ 1,836,130 $ 1,753,844 IBNR 2,863,469 3,077,546 Reserve for losses and loss expenses $ 4,699,599 $ 4,831,390 The following table represents an analysis of paid and unpaid losses and loss expenses incurred and a reconciliation of the beginning and ending unpaid losses and loss expenses for the three and six months ended June 30, 2018 and 2017 : Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Reserve for losses and loss expenses, beginning of period $ 4,632,629 $ 3,052,745 $ 4,831,390 $ 2,995,195 Loss reserves recoverable (979,944 ) (451,856 ) (1,233,997 ) (430,421 ) Net reserves for losses and loss expenses, beginning of period 3,652,685 2,600,889 3,597,393 2,564,774 Net reserves acquired — 23,753 — 23,753 Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in: Current year 489,181 339,439 818,296 670,255 Prior years (12,571 ) (43,290 ) (20,141 ) (104,521 ) Total incurred losses and loss expenses 476,610 296,149 798,155 565,734 Foreign exchange (gain) loss (30,348 ) 20,216 (14,721 ) 32,533 Less net losses and loss expenses paid in respect of losses occurring in: Current year (61,340 ) (42,758 ) (81,075 ) (50,456 ) Prior years (308,958 ) (193,265 ) (571,103 ) (431,354 ) Total net paid losses (370,298 ) (236,023 ) (652,178 ) (481,810 ) Net reserve for losses and loss expenses, end of period 3,728,649 2,704,984 3,728,649 2,704,984 Loss reserves recoverable 970,950 600,207 970,950 600,207 Reserve for losses and loss expenses, end of period $ 4,699,599 $ 3,305,191 $ 4,699,599 $ 3,305,191 Incurred losses and loss expenses comprise: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Gross losses and loss expenses $ 535,438 $ 410,421 $ 784,219 $ 746,863 Reinsurance recoveries (58,828 ) (114,272 ) 13,936 (181,129 ) Net incurred losses and loss expenses $ 476,610 $ 296,149 $ 798,155 $ 565,734 The net (favorable) adverse development on prior accident years by segment and line of business for the three and six months ended June 30, 2018 and 2017 was as follows: Three Months Ended June 30, 2018 Property Specialty - Short-tail Specialty - Other Total Reinsurance Segment $ (9,634 ) $ (10,273 ) $ 5,097 $ (14,810 ) Insurance Segment 4,792 4,986 (4,814 ) 4,964 Asset Management Segment (1,666 ) (1,059 ) — (2,725 ) Net (favorable) adverse development $ (6,508 ) $ (6,346 ) $ 283 $ (12,571 ) Three Months Ended June 30, 2017 Property Specialty - Short-tail Specialty - Other Total Reinsurance Segment $ (697 ) $ (14,344 ) $ (667 ) $ (15,708 ) Insurance Segment (5,347 ) (9,349 ) (9,034 ) (23,730 ) Asset Management Segment (3,097 ) (755 ) — (3,852 ) Net favorable development $ (9,141 ) $ (24,448 ) $ (9,701 ) $ (43,290 ) The net favorable development on prior accident years for the three months ended June 30, 2018 and 2017 was primarily driven by favorable development on attritional losses. Six Months Ended June 30, 2018 Property Specialty - Short-tail Specialty - Other Total Reinsurance Segment $ (14,456 ) $ (23,724 ) $ 5,532 $ (32,648 ) Insurance Segment 8,860 (7,215 ) (12,229 ) (10,584 ) Asset Management Segment 23,534 (443 ) — 23,091 Net adverse (favorable) development $ 17,938 $ (31,382 ) $ (6,697 ) $ (20,141 ) Six Months Ended June 30, 2017 Property Specialty - Short-tail Specialty - Other Total Reinsurance Segment $ (4,759 ) $ (41,092 ) $ (981 ) $ (46,832 ) Insurance Segment (14,013 ) (21,112 ) (15,294 ) (50,419 ) Asset Management Segment (7,492 ) 222 — (7,270 ) Net favorable development $ (26,264 ) $ (61,982 ) $ (16,275 ) $ (104,521 ) The net favorable development on prior accident years for the six months ended June 30, 2018 and 2017 was primarily driven by favorable development on attritional losses.

Reinsurance

Reinsurance	6 Months Ended
	Jun. 30, 2018
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance The Company’s reinsurance balances recoverable at June 30, 2018 and December 31, 2017 were as follows: June 30, 2018 December 31, 2017 Loss reserves recoverable on unpaid: Case reserves $ 287,141 $ 275,450 IBNR 683,809 958,547 Total loss reserves recoverable 970,950 1,233,997 Paid losses recoverable 71,876 46,873 Total reinsurance recoverable $ 1,042,826 $ 1,280,870 (a) Credit risk The cession of reinsurance does not legally discharge the Company from its primary liability for the full amount of the (re)insurance policies it writes, and the Company is required to pay the loss and bear collection risk regarding reinsurers’ obligations under reinsurance and retrocession agreements. Validus records provisions for uncollectible reinsurance recoverable when collection becomes unlikely due to the reinsurer’s inability to pay. To the extent the creditworthiness of the Company’s reinsurers were to deteriorate due to adverse events affecting the reinsurance industry, such as a large number of major catastrophes, actual uncollectible amounts could be significantly greater than the Company’s provision. Amounts recoverable from reinsurers are estimated in a manner consistent with the underlying loss reserves. The Company evaluates the financial condition of its reinsurers and monitors concentration of credit risk arising from its exposure to individual reinsurers. The reinsurance program is generally placed with reinsurers whose rating, at the time of placement, is A- or better as rated by Standard & Poor’s or the equivalent with other rating agencies. Exposure to a single reinsurer is also controlled with restrictions dependent on rating. As at June 30, 2018 , $1,033,890 or 99.1% ( December 31, 2017 : $1,270,503 or 99.2% ) of the Company’s reinsurance balances recoverable were either fully collateralized or recoverable from reinsurers rated A- or better. Information regarding the Company’s concentration of credit risk arising from its exposure to individual reinsurers as at June 30, 2018 and December 31, 2017 is as follows: June 30, 2018 December 31, 2017 Reinsurance Recoverable % of Total Reinsurance Recoverable % of Total Top 10 reinsurers $ 857,819 82.2 % $ 1,055,445 82.5 % Other reinsurers’ balances > $1 million 176,212 17.0 % 218,226 17.0 % Other reinsurers’ balances < $1 million 8,795 0.8 % 7,199 0.5 % Total $ 1,042,826 100.0 % $ 1,280,870 100.0 % June 30, 2018 Top 10 Reinsurers Rating Reinsurance Recoverable % of Total Fully collateralized reinsurers NR $ 400,415 38.4 % Everest Re A+ 120,146 11.5 % Lloyd's Syndicates A+ 75,841 7.3 % Swiss Re AA- 49,857 4.8 % Munich Re AA- 46,444 4.5 % Hannover Re AA- 46,353 4.4 % Transatlantic Re A+ 43,050 4.1 % Qatar Insurance Company A 31,107 3.0 % Partner Re A+ 23,283 2.2 % Markel A 21,323 2.0 % Total $ 857,819 82.2 % NR: Not rated December 31, 2017 Top 10 Reinsurers Rating Reinsurance Recoverable % of Total Fully collateralized reinsurers NR $ 459,339 35.9 % Everest Re A+ 128,206 10.0 % Munich Re AA- 94,180 7.4 % Lloyd's Syndicates A+ 74,277 5.8 % Federal Crop Insurance Corporation (a) 68,745 5.4 % Swiss Re AA- 65,218 5.1 % Hannover Re AA- 53,523 4.2 % Qatar Insurance Company A 50,160 3.9 % Transatlantic Re A+ 33,729 2.6 % Markel A 28,068 2.2 % Total $ 1,055,445 82.5 % NR: Not rated (a) The Company participates in a crop reinsurance program sponsored by the U.S. federal government. The Company remains obligated for amounts ceded in the event that its reinsurers or retrocessionaires do not meet their obligations, except for amounts ceded to the U.S. federal government in the Insurance segment agriculture line of business. At June 30, 2018 and December 31, 2017 , the provision for uncollectible reinsurance relating to reinsurance recoverables was $8,003 and $8,848 , respectively.

Share capital

Share capital	6 Months Ended
	Jun. 30, 2018
Stockholders' Equity Note [Abstract]
Share capital	Share capital Prior to July 18, 2018, the Company’s share capital consisted of preferred shares and common shares, each with a par value of $0.175 per share. On July 18, 2018, in connection with the consummation of the Merger, the NYSE suspended trading of the Company’s common shares. The preferred shares will continue to be listed on the NYSE and registered under the Exchange Act. For further details on the Merger, please refer to Note 3, “Business combinations.” Holders of the Company’s preferred shares have no voting rights with respect to matters that generally require the approval of voting shareholders but are entitled to vote in certain extraordinary instances. Holders of common shares were entitled to one vote for each share held, subject to certain voting limitations. The Company is authorized to issue up to an aggregate of 80,000,000 common shares with a par value of $0.01 , and 16,000 preferred shares with a par value of $0.175 per share. (a) Preferred shares 5.875% Non-Cumulative Preferred Shares, Series A (the “Series A Preferred Shares”) On June 13, 2016, the Company issued 6,000 shares of its 5.875% Non-Cumulative Preferred Shares, Series A (the “Series A Preferred Shares”) (equivalent to 6,000,000 Depositary Shares, each of which represents a 1/1,000th interest in a Series A Preferred Share), $0.175 par value and $25,000 liquidation preference per share (equivalent to $25 per Depositary Share). The Series A Preferred Shares were registered and sold under the Securities Act of 1933, as amended, and were issued at a price to the public of $25,000 per share (equivalent to $25 per Depositary Share). After underwriting discounts and expenses, the Company received net proceeds of $144,852 which were used for general corporate purposes. The Depositary Shares, representing the Series A Preferred Shares, are traded on the New York Stock Exchange (“NYSE”) under the symbol “VRPRA.” Holders of the Series A Preferred Shares have no voting rights, except with respect to certain fundamental changes in the terms of the Series A Preferred Shares and in the case of certain dividend non-payments or as otherwise required by Bermuda law or the Company’s bye-laws. 5.800% Non-Cumulative Preferred Shares, Series B (the “Series B Preferred Shares”) On June 12, 2017, the Company issued 10,000 shares of its 5.800% Non-Cumulative Preferred Shares, Series B (the “Series B Preferred Shares”) (equivalent to 10,000,000 Depositary Shares, each of which represents a 1/1,000th interest in a Series B Preferred Share), $0.175 par value and $25,000 liquidation preference per share (equivalent to $25 per Depositary Share). The Series B Preferred Shares were registered and sold under the Securities Act of 1933, as amended, and were issued at a price to the public of $25,000 per share (equivalent to $25 per Depositary Share). After underwriting discounts and expenses, the Company received net proceeds of $241,686 which were used for general corporate purposes. The Depositary Shares, representing the Series B Preferred Shares, are traded on the New York Stock Exchange (“NYSE”) under the symbol “VRPRB.” Holders of the Series B Preferred Shares have no voting rights, except with respect to certain fundamental changes in the terms of the Series B Preferred Shares and in the case of certain dividend non-payments or as otherwise required by Bermuda law or the Company’s bye-laws. The Company had 6,000 Series A Preferred Shares and 10,000 Series B Preferred Shares issued and outstanding as at June 30, 2018 and December 31, 2017 . For further information regarding the Company’s preferred shares refer to Note 16(a), “Share capital,” included within the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 . (b) Common shares The holders of common shares were entitled to receive dividends and are allocated one vote per share , provided that, if the controlled shares of any shareholder or group of related shareholders constituted more than 9.09 percent of the outstanding common shares of the Company, their voting power would be reduced to 9.09 percent. The Company has repurchased 81,035,969 common shares for an aggregate purchase price of $2,730,975 from the inception of its share repurchase program to June 30, 2018 . The Company had $293,426 remaining under its authorized share repurchase program as of June 30, 2018 . The following table is a summary of the common shares issued and outstanding during the six months ended June 30, 2018 and 2017 : Six Months Ended June 30, 2018 2017 Common shares issued, beginning of period 161,994,491 161,279,976 Restricted share awards vested, net of shares withheld 1,015,069 597,021 Restricted share units vested, net of shares withheld 63,702 14,948 Performance shares vested, net of shares withheld 113,627 42,410 Common shares issued, end of period 163,186,889 161,934,355 Treasury shares, end of period (82,674,941 ) (82,415,774 ) Common shares outstanding, end of period 80,511,948 79,518,581 (c) Dividends On May 4, 2018, the Company announced a quarterly cash dividend of $0.38 (2017: $0.38 ) per common share and cash dividends of $0.3671875 (2017: $0.3671875 ) and $0.3625000 per depository share on the outstanding Series A and Series B Preferred Shares, respectively. The common share dividend was paid on May 30, 2018 to holders of record on May 15, 2018 . The preferred share dividends were paid on June 15, 2018 to shareholders of record on June 1, 2018 . On February 7, 2018, the Company announced a quarterly cash dividend of $0.38 (2017: $0.38 ) per common share and cash dividends of $0.3671875 (2017: $0.3671875 ) and $0.3625000 per depository share on the outstanding Series A and Series B Preferred Shares, respectively. The common share dividend was paid on March 29, 2018 to holders of record on March 15, 2018 . The preferred share dividends were paid on March 15, 2018 to shareholders of record on March 1, 2018.

Stock plans

Stock plans	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock plans	Stock plans (a) Long Term Incentive Plan The Company’s Amended and Restated 2005 Long Term Incentive Plan (“LTIP”) provided for grants to employees of options, stock appreciation rights (“SARs”), restricted shares, restricted share units, performance shares, dividend equivalents or other share-based awards. As at June 30, 2018, the total number of shares reserved for issuance under the LTIP were 2,753,292 , of which 479,086 shares were remaining. The LTIP was administered by the Compensation Committee of the Board of Directors. No SARs were granted. The grant date fair value of each award was established at the fair market value of the Company’s common shares at the date of grant. (i) Options The Company did not grant any stock option awards after September 4, 2009. These stock option awards were fully amortized as at December 31, 2012, and the final options outstanding were exercised during the year ended December 31, 2017. While outstanding, the Company’s options could be exercised for voting common shares upon vesting and had a term of ten years. The fair value of the option awards at the date of grant was determined using the Black-Scholes option-pricing model. Expected volatility was based on the stock price volatility of comparable publicly-traded companies. The Company used the simplified method consistent with U.S. GAAP authoritative guidance on stock compensation expenses to estimate expected lives for options granted during the period. Activity with respect to options for the six months ended June 30, 2017 was as follows: Options Weighted Average Grant Date Fair Value Weighted Average Grant Date Exercise Price Options outstanding, beginning and end of period 26,136 $ 6.78 $ 23.48 (ii) Restricted share awards Restricted shares granted under the LTIP vested either pro rata or 100% at the end of the required service period and contained certain restrictions during the vesting period, relating to, among other things, forfeiture in the event of termination of employment, and transferability. The Company recognized share compensation expenses in respect of restricted share awards during the three and six months ended June 30, 2018 of $7,190 ( 2017 : $9,745 ) and $15,303 ( 2017 : $18,789 ), respectively. The expenses represent the proportionate accrual of the fair value of each grant based on the remaining vesting period. Activity with respect to unvested restricted share awards for the six months ended June 30, 2018 and 2017 was as follows: Six Months Ended June 30, 2018 2017 Restricted Share Awards Weighted Average Grant Date Fair Value Restricted Share Awards Weighted Average Grant Date Fair Value Restricted share awards outstanding, beginning of period 2,080,397 $ 43.66 2,469,982 $ 40.89 Restricted share awards granted 1,552 67.64 481,619 53.42 Restricted share awards vested (1,322,774 ) 40.13 (803,764 ) 41.31 Restricted share awards forfeited (15,985 ) 47.32 (39,617 ) 41.98 Restricted share awards outstanding, end of period 743,190 $ 49.92 2,108,220 $ 43.58 At June 30, 2018 , there were $33,551 ( December 31, 2017 : $48,907 ) of total unrecognized share compensation expenses in respect of restricted share awards that are expected to be recognized over a weighted-average period of 2.1 years ( December 31, 2017 : 2.3 years ). (iii) Restricted share units Restricted share units under the LTIP vested either ratably or 100% at the end of the required service period and contain certain restrictions during the vesting period, relating to, among other things, forfeiture in the event of termination of employment, and transferability. The Company recognized share compensation expenses in respect of restricted share units during the three and six months ended June 30, 2018 of $284 ( 2017 : $327 ) and $616 ( 2017 : $642 ), respectively. The expenses represent the proportionate accrual of the fair value of each grant based on the remaining vesting period. Activity with respect to unvested restricted share units for the six months ended June 30, 2018 and 2017 was as follows: Six Months Ended June 30, 2018 2017 Restricted Share Units Weighted Average Grant Date Fair Value Restricted Share Units Weighted Average Grant Date Fair Value Restricted share units outstanding, beginning of period 109,394 $ 42.20 112,808 $ 40.95 Restricted share units granted — — 12,236 53.40 Restricted share units vested (81,139 ) 39.27 (18,241 ) 41.66 Restricted share units issued in lieu of cash dividends 2,105 42.25 1,468 40.98 Restricted share units forfeited (17 ) 44.63 — — Restricted share units outstanding, end of period 30,343 $ 50.04 108,271 $ 42.24 At June 30, 2018 , there were $1,319 ( December 31, 2017 : $1,909 ) of total unrecognized share compensation expenses in respect of restricted share units that are expected to be recognized over a weighted-average period of 2.3 years ( December 31, 2017 : 2.4 years ). (iv) Performance share awards Performance share awards vested three years after the grant date, with the grant date fair value of each share awarded recognized evenly over this period. The number of performance shares initially granted was adjusted via “conversion adjustments” to reflect the compounded growth in the Dividend-Adjusted Book Value per Diluted Share over the three years as determined by the Company’s Compensation Committee. The cumulative compensation expense recognized and unrecognized as at any reporting period date represented the adjusted estimate of performance shares that would ultimately be awarded, valued at their original grant date fair values. The Company recognized share compensation expenses in respect of performance share awards during the three and six months ended June 30, 2018 of $8,566 ( 2017 : $1,074 ) and $9,850 ( 2017 : $1,206 ), respectively. The share compensation expenses represent the proportionate accrual of the fair value of each grant based on the remaining vesting period. Activity with respect to unvested performance share awards for the six months ended June 30, 2018 and 2017 was as follows: Six Months Ended June 30, 2018 2017 Performance Share Awards Weighted Average Grant Date Fair Value Performance Share Awards Weighted Average Grant Date Fair Value Performance share awards outstanding, beginning of period 314,068 $ 49.37 285,820 $ 44.53 Performance share awards granted — — 107,209 53.40 Performance share awards vested (142,749 ) 45.03 (52,639 ) 37.33 Performance share awards conversion adjustment 235,564 49.37 (26,322 ) 36.82 Performance share awards outstanding, end of period 406,883 $ 50.89 314,068 $ 49.37 At June 30, 2018 , there were $9,501 ( December 31, 2017 : $7,813 ) of total unrecognized share compensation expenses in respect of performance share awards that are expected to be recognized over a weighted-average period of 1.6 years ( December 31, 2017 : 1.9 years ). (b) Total share compensation expenses The breakdown of share compensation expenses by award type for the periods indicated was as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Restricted share awards $ 7,190 $ 9,745 $ 15,303 $ 18,789 Restricted share units 284 327 616 642 Performance share awards 8,566 1,074 9,850 1,206 Total $ 16,040 $ 11,146 $ 25,769 $ 20,637

Debt and financing arrangements

Debt and financing arrangements	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Debt and financing arrangements	Debt and financing arrangements The Company’s financing structure is composed of debentures and senior notes payable along with credit and other facilities. For further information regarding the Company’s financing structure refer to Note 19, “Debt and financing arrangements,” included within the Company’s Annual Report on Form 10-K for the year ended December 31, 2017 . (a) Senior Notes and Junior Subordinated Deferrable Debentures The Company’s outstanding debentures and senior notes payable as at June 30, 2018 and December 31, 2017 were as follows: June 30, 2018 December 31, 2017 Deferrable debentures 2006 Junior Subordinated $ 150,000 $ 150,000 2007 Junior Subordinated 139,800 139,800 Flagstone 2006 Junior Subordinated 135,201 135,608 Flagstone 2007 Junior Subordinated 113,750 113,750 Total debentures payable 538,751 539,158 2010 Senior Notes due 2040 250,000 250,000 Less: Unamortized debt issuance costs (4,336 ) (4,436 ) Total senior notes payable 245,664 245,564 Total debentures and senior notes payable $ 784,415 $ 784,722 The following table summarizes the key terms of the Company’s Senior Notes and Junior Subordinated deferrable debentures: Description Issuance date Issued Maturity date Interest Rate as at Interest payments due Issuance Date June 30, 2018 2006 Junior Subordinated Deferrable Debentures June 15, 2006 $ 150,000 June 15, 2036 9.069 % (a) 5.831 % (e) Quarterly Flagstone 2006 Junior Subordinated Deferrable Debentures August 23, 2006 $ 135,201 September 15, 2036 3.540 % (b) 6.463 % (e) Quarterly 2007 Junior Subordinated Deferrable Debentures June 21, 2007 $ 200,000 June 15, 2037 8.480 % (c) 5.180 % (e) Quarterly Flagstone 2007 Junior Subordinated Deferrable Debentures June 8, 2007 $ 100,000 July 30, 2037 3.000 % (b) 5.900 % (e) Quarterly Flagstone 2007 Junior Subordinated Deferrable Debentures September 20, 2007 $ 25,000 September 15, 2037 3.100 % (b) 5.983 % (e) Quarterly 2010 Senior Notes due 2040 January 26, 2010 $ 250,000 January 26, 2040 8.875 % (d) 8.875 % (d) Semi-annually in arrears (a) Fixed interest rate for 5 years , floating interest rate of three-month LIBOR plus 3.550% thereafter, reset quarterly. (b) Floating interest rate of three-month LIBOR plus amount stated, reset quarterly. (c) Fixed interest rate for 5 years , floating interest rate of three-month LIBOR plus 2.950% thereafter, reset quarterly. (d) Fixed interest rate. (e) Fixed interest rate as a result of interest rate swap contracts entered into by the Company. (b) Credit and other facilities The Company’s outstanding credit facilities as at June 30, 2018 and December 31, 2017 were as follows: June 30, 2018 Credit facility Commitment Outstanding (a) Drawn (b) Cash and investments pledged as collateral $85,000 syndicated unsecured letter of credit facility $ 85,000 $ — $ — $ — $300,000 syndicated secured letter of credit facility 300,000 98,267 — 123,632 $100,000 secured bi-lateral letter of credit facility 100,000 4,238 — 22,432 $25,000 IPC bi-lateral facility 25,000 7,702 — — $236,000 Flagstone bi-lateral facility 236,000 107,506 — 155,064 $65,000 unsecured revolving credit facility 65,000 — — — $100,000 unsecured revolving credit facility 100,000 — — — FHLB secured facility 548,898 206,000 206,000 238,499 Total credit facilities $ 1,459,898 $ 423,713 $ 206,000 $ 539,627 (a) Indicates utilization of commitment amount. (b) Represents drawn borrowings included in accounts payable and accrued expenses. December 31, 2017 Credit facility Commitment Outstanding (a) Drawn (b) Cash and investments pledged as collateral $85,000 syndicated unsecured letter of credit facility $ 85,000 $ — $ — $ — $300,000 syndicated secured letter of credit facility 300,000 92,979 — 118,188 $24,000 secured bi-lateral letter of credit facility 24,000 5,765 — 22,340 $25,000 IPC bi-lateral facility 25,000 7,754 — — $236,000 Flagstone bi-lateral facility 236,000 115,682 — 184,569 $65,000 unsecured revolving credit facility 65,000 — — — $100,000 unsecured revolving credit facility 100,000 — — — FHLB secured facility 484,096 206,000 206,000 251,767 Total credit facilities $ 1,319,096 $ 428,180 $ 206,000 $ 576,864 (a) Indicates utilization of commitment amount. (b) Represents drawn borrowings included in accounts payable and accrued expenses. On January 24, 2018, the Company increased the size of the secured bi-lateral letter of credit facility with Citibank Europe plc (the “Secured bi-lateral LOC facility”) from $24,000 to $100,000 . All covenants and restrictions under the Secured bi-lateral LOC facility remain unchanged. As of June 30, 2018 , $4,238 ( December 31, 2017 : $5,765 ) of letters of credit were outstanding under the Secured bi-lateral LOC facility. As of June 30, 2018 and December 31, 2017 , the Company was in compliance with all covenants and restrictions under its credit facilities. (c) Finance expenses Finance expenses consist of interest on the Junior Subordinated Deferrable Debentures and the 2010 Senior Notes, the amortization of debt offering costs, credit facility fees, bank and other charges and AlphaCat financing fees as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 2006 Junior Subordinated Deferrable Debentures $ 2,212 $ 2,211 $ 4,398 $ 4,398 2007 Junior Subordinated Deferrable Debentures 1,831 1,831 3,641 3,641 Flagstone 2006 Junior Subordinated Deferrable Debentures 2,246 2,248 4,473 4,469 Flagstone 2007 Junior Subordinated Deferrable Debentures 1,722 1,751 3,435 3,474 2010 Senior Notes 5,598 5,598 11,195 11,195 Credit facilities 464 403 880 621 Bank and other charges 207 131 470 282 AlphaCat fees (a) 30 36 81 72 Total finance expenses $ 14,310 $ 14,209 $ 28,573 $ 28,152 (a) Includes finance expenses incurred by AlphaCat Managers Ltd. in relation to fund raising for the AlphaCat sidecars, the AlphaCat ILS funds and AlphaCat direct.

Accumulated other comprehensive

Accumulated other comprehensive loss	6 Months Ended
	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive loss	Accumulated other comprehensive income (loss) The changes in accumulated other comprehensive income (loss), by component for the three and six months ended June 30, 2018 and 2017 are as follows: Three Months Ended June 30, 2018 Foreign currency translation adjustment Minimum pension liability Cash flow hedge Total Balance, net of tax, beginning of period $ (16,380 ) $ 2,681 $ 23,104 $ 9,405 Other comprehensive (loss) income, net of tax (2,737 ) 342 3,035 640 Amounts reclassified from accumulated other comprehensive income (loss) — — (186 ) (186 ) Balance, net of tax, end of period $ (19,117 ) $ 3,023 $ 25,953 $ 9,859 Three Months Ended June 30, 2017 Foreign currency translation adjustment Minimum pension liability Cash flow hedge Total Balance, net of tax, beginning of period $ (21,677 ) $ (82 ) $ (694 ) $ (22,453 ) Other comprehensive income (loss), net of tax 1,489 1,184 (144 ) 2,529 Balance, net of tax, end of period $ (20,188 ) $ 1,102 $ (838 ) $ (19,924 ) Six Months Ended June 30, 2018 Foreign currency translation adjustment Minimum pension liability Cash flow hedge Total Balance, net of tax, beginning of period $ (18,217 ) $ 2,719 $ (6,694 ) $ (22,192 ) Other comprehensive (loss) income, net of tax (900 ) 304 31,798 31,202 Amounts reclassified from accumulated other comprehensive income (loss) — — 849 849 Balance, net of tax, end of period $ (19,117 ) $ 3,023 $ 25,953 $ 9,859 Six Months Ended June 30, 2017 Foreign currency translation adjustment Minimum pension liability Cash flow hedge Total Balance, net of tax, beginning of period $ (22,274 ) $ (150 ) $ (792 ) $ (23,216 ) Other comprehensive income (loss), net of tax 2,086 1,252 (46 ) 3,292 Balance, net of tax, end of period $ (20,188 ) $ 1,102 $ (838 ) $ (19,924 )

Commitments and contingencies

Commitments and contingencies	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and contingencies (a) Funds at Lloyd’s The Company operates in Lloyd’s through a corporate member, Talbot 2002 Underwriting Capital Ltd (“T02”), which is the sole participant in Lloyd’s Syndicate 1183 (the “Talbot Syndicate”). Lloyd’s sets T02’s Economic Capital Assessment (“ECA”) annually based on the Talbot Syndicate’s business plan, rating environment and reserving environment together with input arising from Lloyd’s discussions with regulatory and rating agencies, and other parties. This ECA is satisfied by syndicate net assets determined on a basis consistent with Solvency II, an EU directive covering capital adequacy, risk management and regulatory reporting for insurers. Any syndicate net liabilities on a Solvency II basis are required to be funded in addition to the ECA. Such additional funds, known as Funds at Lloyd’s (“FAL”), comprises cash and investments. The Company provided FAL in the amount of $661,600 during the fourth quarter of 2017 ( 2016 : $583,600 ). The amounts which are provided as FAL are not available for distribution to the Company for the payment of dividends. T02 may also be required to maintain funds under the control of Lloyd’s in excess of its capital requirement and such funds also may not be available for distribution to the Company for the payment of dividends. (b) Lloyd’s Central Fund Whenever a member of Lloyd’s is unable to pay its debts to policyholders, such debts may be payable by the Lloyd’s Central Fund. If Lloyd’s determines that the Central Fund needs to be increased, it has the power to assess premium levies on current Lloyd’s members up to 3% of a member’s underwriting capacity in any one year. The Company does not believe that any assessment is likely in the foreseeable future and has not provided any allowance for such an assessment. However, based on the Company’s 2018 estimated premium income at Lloyd’s of £650,000 , at June 30, 2018 using an exchange rate of £1 equals $1.32 and assuming the maximum 3% assessment, the Company would be assessed approximately $25,740 ( December 31, 2017 : $26,325 ). (c) Unfunded investment commitments As at June 30, 2018 and December 31, 2017 , the Company had total unfunded investment commitments related to the following: Unfunded investment commitments June 30, 2018 December 31, 2017 Fixed maturity investments (a) $ 26,477 $ 22,082 Other investments (b) 83,894 86,697 Investments in investment affiliates (c) 95,788 125,996 Total unfunded investment commitments $ 206,159 $ 234,775 (a) The Company has an outstanding commitment to participate in certain secured loan facilities through participation agreements with an established loan originator. (b) The Company’s total capital commitments related to other investments as at June 30, 2018 was $268,000 ( December 31, 2017 : $268,000 ). (c) Refer to Note 4 (c), “Investments in investment affiliates.”

Related party transactions

Related party transactions	6 Months Ended
	Jun. 30, 2018
Related Party Transactions [Abstract]
Related party transactions	Related party transactions The transactions listed below are classified as related party transactions as principals and/or directors of each counterparty were members of the Company’s board of directors as at June 30, 2018. (a) Aquiline Capital Partners LLC (“Aquiline Capital”) Wellington Aquiline Capital are shareholders of Wellington Insurance Company (“Wellington”) and Christopher E. Watson serves as a director of Wellington. Pursuant to reinsurance agreements with a subsidiary of Wellington, the Company recognized gross premiums written during the three and six months ended June 30, 2018 of $16 and $798 ( 2017 : $1,144 and $4,118 ) with $542 included in premiums receivable at June 30, 2018 ( December 31, 2017 : $211 ). The Company also recognized premium adjustments during the three and six months ended June 30, 2018 of $(282) and $496 ( 2017 : $1,676 and $2,537 ). Aquiline II, Aquiline III, Aquiline Tech and Aquiline Armour Jeffrey W. Greenberg and Christopher E. Watson, directors of the Company as at June 30, 2018, serve as managing principal and senior principal, respectively, of Aquiline Capital. Additional information related to the Company’s investments in Aquiline II, III, Tech and Armour is disclosed in Note 4 (c), “Investments in investment affiliates.” The Company had, as of June 30, 2018 and December 31, 2017 , investments in Aquiline II, III, Tech and Armour with a total value of $127,247 and $100,137 and outstanding unfunded commitments of $95,788 and $125,996 , respectively. For the three and six months ended June 30, 2018 , the Company incurred $3,767 and $3,899 ( 2017 : $130 and $486 ), respectively, in partnership fees associated with these investments. (b) Other Certain shareholders of the Company and their affiliates, as well as employees of entities associated with directors and officers may have purchased insurance and/or reinsurance from the Company in the ordinary course of business. The Company does not believe these transactions to be material.

Earnings per share

Earnings per share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Earnings per common share	Earnings per common share The following table sets forth the computation of basic (loss) earnings per common share and (loss) earnings per diluted common share available to Validus common shareholders for the three and six months ended June 30, 2018 and 2017 : Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Basic (loss) earnings per common share Net (loss) income (attributable) available to Validus common shareholders (52,898 ) 101,095 (56,976 ) 195,656 Weighted average number of common shares outstanding 79,650,474 79,270,561 79,488,081 79,202,116 Basic (loss) earnings per share (attributable) available to Validus common shareholders $ (0.66 ) $ 1.28 $ (0.72 ) $ 2.47 (Loss) earnings per diluted common share Net (loss) income (attributable) available to Validus common shareholders $ (52,898 ) $ 101,095 $ (56,976 ) $ 195,656 Weighted average number of common shares outstanding 79,650,474 79,270,561 79,488,081 79,202,116 Share equivalents: Stock options — 14,739 — 15,059 Unvested restricted shares — 1,587,151 — 1,644,823 Weighted average number of diluted common shares outstanding 79,650,474 80,872,451 79,488,081 80,861,998 (Loss) earnings per diluted common share (attributable) available to Validus common shareholders $ (0.66 ) $ 1.25 $ (0.72 ) $ 2.42 Earnings per diluted common share assumes the exercise of all dilutive stock options and restricted stock grants. Due to the net loss incurred during the three and six months ended June 30, 2018 , share equivalents were not included in the computation of loss per diluted share due to their anti-dilutive effect. Share equivalents that would result in the issuance of common shares of 412,603 and 207,054 were outstanding for the three and six months ended June 30, 2017 , respectively, but were not included in the computation of earnings per diluted share because the effect would be anti-dilutive.

Segment information

Segment information	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segment information	Segment information The Company conducts its operations worldwide through three reportable segments, which have been determined under ASC Topic 280 “Segment Reporting” to be Reinsurance, Insurance and Asset Management. The Company’s reportable segments are strategic business units that offer different products and services. They are managed and have capital allocated separately because each segment undertakes different strategies. A description of each of the Company’s reportable segments and its Corporate and Investments function is as follows: Reinsurance Segment The Reinsurance segment operates globally and is primarily focused on treaty reinsurance within the following lines and classes of business: • Property: catastrophe excess of loss, per risk excess of loss, proportional and treaty; • Specialty - Short-tail: aerospace and aviation, agriculture, composite, marine, other specialty (including contingency, crisis management and life and accident & health), technical lines, terrorism, trade credit and workers’ compensation; and • Specialty - Other: casualty and financial lines of business. Insurance Segment The Insurance segment operates globally and focuses on specialty insurance within both the Lloyd’s and the U.S. commercial insurance markets and is focused on a wide range of insurance products within the following lines and classes of business: • Property: direct property and downstream energy and power; • Specialty - Short-tail: accident & health, agriculture, aviation, contingency, marine, and political lines (including war and political violence); and • Specialty - Other: financial, liability (including general liability, professional liability, products liability and miscellaneous malpractice), marine and energy, political risk and products and airports. Asset Management Segment The Asset Management segment leverages the Company’s underwriting and analytical expertise and earns management and performance fees primarily through the management of ILS funds and sidecars. Corporate and Investments The Company’s Corporate and Investments function, which includes the activities of the parent company, carries out certain functions for the group, including investment management. Corporate and Investments includes investment income on a managed basis and other non-segment expenses, predominantly general and administrative, stock compensation, finance and transaction expenses. Transaction expenses are primarily composed of legal and financial advisory services incurred in connection with the Company’s Merger with AIG in 2018, and the acquisition of CRS in 2017. Corporate and Investments also includes the activities of certain key executives such as the Chief Executive Officer and Chief Financial Officer. For reporting purposes, Corporate and Investments is reflected separately; however, it is not considered a reportable segment under these circumstances. Other reconciling items include, but are not limited to, the elimination of certain inter segment revenues and expenses and other items that are not allocated to the reportable segments. The following tables summarize the results of our reportable segments and “Corporate and Investments” function: Three Months Ended June 30, Six Months Ended June 30, Reinsurance Segment Information 2018 2017 2018 2017 Underwriting revenues Gross premiums written $ 360,588 $ 330,534 $ 1,126,161 $ 973,675 Reinsurance premiums ceded (16,368 ) (10,278 ) (206,562 ) (124,724 ) Net premiums written 344,220 320,256 919,599 848,951 Change in unearned premiums (106,697 ) (61,948 ) (457,324 ) (358,988 ) Net premiums earned 237,523 258,308 462,275 489,963 Other insurance related income — 1 2 3 Total underwriting revenues 237,523 258,309 462,277 489,966 Underwriting deductions Losses and loss expenses 117,338 114,341 220,811 195,222 Policy acquisition costs 52,157 49,966 100,497 93,501 General and administrative expenses 26,522 22,204 55,437 42,173 Share compensation expenses 3,972 2,725 6,635 5,348 Total underwriting deductions 199,989 189,236 383,380 336,244 Underwriting income $ 37,534 $ 69,073 $ 78,897 $ 153,722 Selected ratios: Ratio of net to gross premiums written 95.5 % 96.9 % 81.7 % 87.2 % Losses and loss expense ratio 49.4 % 44.3 % 47.8 % 39.8 % Policy acquisition cost ratio 22.0 % 19.3 % 21.7 % 19.1 % General and administrative expense ratio 12.8 % 9.7 % 13.4 % 9.7 % Expense ratio 34.8 % 29.0 % 35.1 % 28.8 % Combined ratio 84.2 % 73.3 % 82.9 % 68.6 % Three Months Ended June 30, Six Months Ended June 30, Insurance Segment Information 2018 2017 2018 2017 Underwriting revenues Gross premiums written $ 384,240 $ 360,057 $ 1,170,035 $ 742,847 Reinsurance premiums ceded (81,887 ) (49,315 ) (273,524 ) (128,315 ) Net premiums written 302,353 310,742 896,511 614,532 Change in unearned premiums 97,446 (5,875 ) (197,174 ) (30,571 ) Net premiums earned 399,799 304,867 699,337 583,961 Other insurance related income 35 728 2,205 1,724 Total underwriting revenues 399,834 305,595 701,542 585,685 Underwriting deductions Losses and loss expenses 342,854 180,741 526,243 367,351 Policy acquisition costs 57,650 60,137 117,707 121,329 General and administrative expenses 75,110 53,596 143,160 98,872 Share compensation expenses 4,242 3,702 7,231 7,075 Total underwriting deductions 479,856 298,176 794,341 594,627 Underwriting (loss) income $ (80,022 ) $ 7,419 $ (92,799 ) $ (8,942 ) Selected ratios: Ratio of net to gross premiums written 78.7 % 86.3 % 76.6 % 82.7 % Losses and loss expense ratio 85.8 % 59.3 % 75.2 % 62.9 % Policy acquisition cost ratio 14.4 % 19.7 % 16.8 % 20.8 % General and administrative expense ratio 19.8 % 18.8 % 21.5 % 18.1 % Expense ratio 34.2 % 38.5 % 38.3 % 38.9 % Combined ratio 120.0 % 97.8 % 113.5 % 101.8 % Three Months Ended June 30, Six Months Ended June 30, Asset Management Segment Information 2018 2017 2018 2017 Fee revenues Third party $ 5,685 $ 5,549 $ 11,894 $ 10,193 Related party 436 644 879 1,275 Total fee revenues 6,121 6,193 12,773 11,468 Expenses General and administrative expenses 4,835 3,549 9,382 7,393 Share compensation expenses 30 83 71 165 Finance expenses 18 44 96 75 Tax expense (benefit) 2 135 (5 ) 134 Foreign exchange losses — 1 1 — Total expenses 4,885 3,812 9,545 7,767 Income before investment income from funds and sidecars 1,236 2,381 3,228 3,701 Investment income (loss) from funds and sidecars (a) AlphaCat Sidecars 102 (21 ) 134 (133 ) AlphaCat ILS Funds - Lower Risk (b) 1,773 1,301 3,007 3,490 AlphaCat ILS Funds - Higher Risk (b) (796 ) 2,600 3,024 4,967 BetaCat ILS Funds 363 263 549 631 Validus' share of investment income from funds and sidecars 1,442 4,143 6,714 8,955 Asset Management segment income $ 2,678 $ 6,524 $ 9,942 $ 12,656 Gross premiums written AlphaCat Sidecars $ 9 $ — $ (134 ) $ 66 AlphaCat ILS Funds - Lower Risk (b) 62,577 53,632 172,527 106,540 AlphaCat ILS Funds - Higher Risk (b) 37,514 43,672 203,410 137,208 AlphaCat Direct (c) 2,278 8,378 13,200 26,794 Total $ 102,378 $ 105,682 $ 389,003 $ 270,608 (a) The investment income (loss) from funds and sidecars is based on equity accounting. (b) Lower risk AlphaCat ILS funds have a maximum permitted portfolio expected loss of less than 7%, whereas higher risk AlphaCat ILS funds have a maximum permitted portfolio expected loss of 7% or greater. The portfolio expected loss represents the average annual loss over the set of simulation scenarios divided by the total limit. (c) AlphaCat Direct includes direct investments from a third party investor in AlphaCat Re. Three Months Ended June 30, Six Months Ended June 30, Corporate and Investments 2018 2017 2018 2017 Managed investments Managed net investment income (a) $ 42,752 $ 38,063 $ 82,543 $ 74,255 Net realized (losses) gains on managed investments (a) (7,432 ) 2,269 (6,290 ) (623 ) Change in net unrealized (losses) gains on managed investments (a) (11,392 ) 15,942 (68,169 ) 30,291 Income from investment affiliates 2,178 9,466 15,246 14,654 Total managed investment return $ 26,106 $ 65,740 $ 23,330 $ 118,577 Corporate expenses General and administrative expenses $ 13,523 $ 16,219 $ 25,832 $ 34,180 Share compensation expenses 7,796 4,636 11,832 8,049 Finance expenses (a) 14,249 14,149 28,339 28,013 Dividends on preferred shares 5,828 2,203 11,656 4,406 Tax (benefit) (a) (7,153 ) (1,122 ) (13,979 ) (4,670 ) Total Corporate expenses $ 34,243 $ 36,085 $ 63,680 $ 69,978 Other items Foreign exchange losses (a) (1,652 ) (7,323 ) (1,655 ) (6,220 ) Other income 538 174 582 268 Transaction expenses (3,837 ) (4,427 ) (11,593 ) (4,427 ) Total other items $ (4,951 ) $ (11,576 ) $ (12,666 ) $ (10,379 ) Total Corporate and Investments $ (13,088 ) $ 18,079 $ (53,016 ) $ 38,220 (a) These items exclude the components which are included in the Asset Management segment income (loss) and amounts which are consolidated from VIEs. The following tables reconcile the results of our reportable segments and “Corporate & Investments” function to the Consolidated results of the Company for the periods indicated: Three Months Ended June 30, 2018 Reinsurance Segment Insurance Segment Asset Management Segment and Consolidated VIEs Corporate & Investments Eliminations Total Underwriting revenues Gross premiums written $ 360,588 $ 384,240 $ 102,378 $ — $ — $ 847,206 Reinsurance premiums ceded (16,368 ) (81,887 ) (9,312 ) — — (107,567 ) Net premiums written 344,220 302,353 93,066 — — 739,639 Change in unearned premiums (106,697 ) 97,446 6,219 — — (3,032 ) Net premiums earned 237,523 399,799 99,285 — — 736,607 Other insurance related income (loss) — 35 (12,261 ) — (4,428 ) (16,654 ) Total underwriting revenues 237,523 399,834 87,024 — (4,428 ) 719,953 Underwriting deductions Losses and loss expenses 117,338 342,854 16,418 — — 476,610 Policy acquisition costs 52,157 57,650 8,974 — — 118,781 General and administrative expenses 26,522 75,110 10,135 13,523 (4,428 ) 120,862 Share compensation expenses 3,972 4,242 30 7,796 — 16,040 Total underwriting deductions 199,989 479,856 35,557 21,319 (4,428 ) 732,293 Underwriting income (loss) $ 37,534 $ (80,022 ) $ 51,467 $ (21,319 ) $ — $ (12,340 ) Net investment return (a) — — 15,508 26,106 — 41,614 Other items (b) — — 1,063 (17,875 ) — (16,812 ) (Income) attributable to AlphaCat investors — — (29,849 ) — — (29,849 ) Net (income) attributable to noncontrolling interests — — (35,511 ) — — (35,511 ) Net income (loss) available (attributable) to Validus common shareholders $ 37,534 $ (80,022 ) $ 2,678 $ (13,088 ) $ — $ (52,898 ) (a) Net investment return includes net investment income, net realized and change in net unrealized gains (losses) on investments and income (loss) from investment affiliates. (b) Other items includes finance expenses, transaction expenses, dividends on preferred shares, tax benefit (expense), foreign exchange gains (losses), income (loss) from operating affiliate and other income (loss). Three Months Ended June 30, 2017 Reinsurance Segment Insurance Segment Asset Management Segment and Consolidated VIEs Corporate & Investments Eliminations Total Underwriting revenues Gross premiums written $ 330,534 $ 360,057 $ 105,682 $ — $ (3,371 ) $ 792,902 Reinsurance premiums ceded (10,278 ) (49,315 ) — — 3,371 (56,222 ) Net premiums written 320,256 310,742 105,682 — — 736,680 Change in unearned premiums (61,948 ) (5,875 ) (37,830 ) — — (105,653 ) Net premiums earned 258,308 304,867 67,852 — — 631,027 Other insurance related income 1 728 5,874 — (5,438 ) 1,165 Total underwriting revenues 258,309 305,595 73,726 — (5,438 ) 632,192 Underwriting deductions Losses and loss expenses 114,341 180,741 1,067 — — 296,149 Policy acquisition costs 49,966 60,137 7,165 — — 117,268 General and administrative expenses 22,204 53,596 9,768 16,219 (5,438 ) 96,349 Share compensation expenses 2,725 3,702 83 4,636 — 11,146 Total underwriting deductions 189,236 298,176 18,083 20,855 (5,438 ) 520,912 Underwriting income (loss) $ 69,073 $ 7,419 $ 55,643 $ (20,855 ) $ — $ 111,280 Net investment return (a) — — 6,562 65,740 — 72,302 Other items (b) — — (201 ) (26,806 ) — (27,007 ) (Income) attributable to AlphaCat investors — — (11,830 ) — — (11,830 ) Net (income) attributable to noncontrolling interests — — (43,650 ) — — (43,650 ) Net income available to Validus common shareholders $ 69,073 $ 7,419 $ 6,524 $ 18,079 $ — $ 101,095 (a) Net investment return includes net investment income, net realized and change in net unrealized gains (losses) on investments and income (loss) from investment affiliates. (b) Other items includes finance expenses, transaction expenses, dividends on preferred shares, tax benefit (expense), foreign exchange gains (losses), income (loss) from operating affiliate and other income (loss). Six Months Ended June 30, 2018 Reinsurance Segment Insurance Segment Asset Management Segment and Consolidated VIEs Corporate & Investments Eliminations Total Underwriting revenues Gross premiums written $ 1,126,161 $ 1,170,035 $ 389,003 $ — $ (5,537 ) $ 2,679,662 Reinsurance premiums ceded (206,562 ) (273,524 ) (9,312 ) — 5,537 (483,861 ) Net premiums written 919,599 896,511 379,691 — — 2,195,801 Change in unearned premiums (457,324 ) (197,174 ) (185,754 ) — — (840,252 ) Net premiums earned 462,275 699,337 193,937 — — 1,355,549 Other insurance related income 2 2,205 15,819 — (9,184 ) 8,842 Total underwriting revenues 462,277 701,542 209,756 — (9,184 ) 1,364,391 Underwriting deductions Losses and loss expenses 220,811 526,243 51,101 — — 798,155 Policy acquisition costs 100,497 117,707 17,033 — — 235,237 General and administrative expenses 55,437 143,160 20,343 25,832 (9,184 ) 235,588 Share compensation expenses 6,635 7,231 71 11,832 — 25,769 Total underwriting deductions 383,380 794,341 88,548 37,664 (9,184 ) 1,294,749 Underwriting income (loss) $ 78,897 $ (92,799 ) $ 121,208 $ (37,664 ) $ — $ 69,642 Net investment return (a) — — 28,243 23,330 — 51,573 Other items (b) — — 1,425 (38,682 ) — (37,257 ) (Income) attributable to AlphaCat investors — — (40,711 ) — — (40,711 ) Net (income) attributable to noncontrolling interests — — (100,223 ) — — (100,223 ) Net income (loss) available (attributable) to Validus common shareholders $ 78,897 $ (92,799 ) $ 9,942 $ (53,016 ) $ — $ (56,976 ) (a) Net investment return includes net investment income, net realized and change in net unrealized gains (losses) on investments and income (loss) from investment affiliates. (b) Other items includes finance expenses, transaction expenses, dividends on preferred shares, tax benefit (expense), foreign exchange gains (losses), income (loss) from operating affiliate and other income (loss). Six Months Ended June 30, 2017 Reinsurance Segment Insurance Segment Asset Management Segment and Consolidated VIEs Corporate & Investments Eliminations Total Underwriting revenues Gross premiums written $ 973,675 $ 742,847 $ 270,608 $ — $ (3,371 ) $ 1,983,759 Reinsurance premiums ceded (124,724 ) (128,315 ) (6,660 ) — 3,371 (256,328 ) Net premiums written 848,951 614,532 263,948 — — 1,727,431 Change in unearned premiums (358,988 ) (30,571 ) (131,469 ) — — (521,028 ) Net premiums earned 489,963 583,961 132,479 — — 1,206,403 Other insurance related income 3 1,724 11,035 — (10,361 ) 2,401 Total underwriting revenues 489,966 585,685 143,514 — (10,361 ) 1,208,804 Underwriting deductions Losses and loss expenses 195,222 367,351 3,161 — — 565,734 Policy acquisition costs 93,501 121,329 14,066 — — 228,896 General and administrative expenses 42,173 98,872 19,409 34,180 (10,361 ) 184,273 Share compensation expenses 5,348 7,075 165 8,049 — 20,637 Total underwriting deductions 336,244 594,627 36,801 42,229 (10,361 ) 999,540 Underwriting income (loss) $ 153,722 $ (8,942 ) $ 106,713 $ (42,229 ) $ — $ 209,264 Net investment return (a) — — 11,311 118,577 — 129,888 Other items (b) — — 187 (38,128 ) — (37,941 ) (Income) attributable to AlphaCat investors — — (19,333 ) — — (19,333 ) Net (income) attributable to noncontrolling interests — — (86,222 ) — — (86,222 ) Net income (loss) available (attributable) to Validus common shareholders $ 153,722 $ (8,942 ) $ 12,656 $ 38,220 $ — $ 195,656 (a) Net investment return includes net investment income, net realized and change in net unrealized gains (losses) on investments and income (loss) from investment affiliates. (b) Other items includes finance expenses, transaction expenses, dividends on preferred shares, tax benefit (expense), foreign exchange gains (losses), income (loss) from operating affiliate and other income (loss). The Company’s exposures are generally diversified across geographic zones. The following tables set forth the gross premiums written allocated to the territory of coverage exposure for the periods indicated: Gross Premiums Written Three Months Ended June 30, 2018 Reinsurance Segment Insurance Segment Asset Management Segment Eliminations Total % United States $ 149,298 $ 188,253 $ 70,762 $ — $ 408,313 48.2 % Worldwide excluding United States (a) 12,962 41,430 (102 ) — 54,290 6.4 % Australia and New Zealand 33 (2,992 ) — — (2,959 ) (0.3 )% Europe 3,091 7,048 — — 10,139 1.2 % Latin America and Caribbean 10,581 25,429 — — 36,010 4.3 % Japan 43,467 2,213 1,833 — 47,513 5.6 % Canada 4,955 931 359 — 6,245 0.7 % Rest of the world (b) 5,971 24,559 — — 30,530 3.6 % Sub-total, non United States 81,060 98,618 2,090 — 181,768 21.5 % Worldwide including United States (a) 59,259 30,789 29,526 — 119,574 14.1 % Other locations non-specific (c) 70,971 66,580 — — 137,551 16.2 % Total $ 360,588 $ 384,240 $ 102,378 $ — $ 847,206 100.0 % Gross Premiums Written Three Months Ended June 30, 2017 Reinsurance Segment Insurance Segment Asset Management Segment Eliminations Total % United States $ 108,727 $ 157,048 $ 70,048 $ (3,371 ) $ 332,452 41.9 % Worldwide excluding United States (a) 5,378 37,295 870 — 43,543 5.5 % Australia and New Zealand 3,388 1,764 2,003 — 7,155 0.9 % Europe 1,168 5,711 (15 ) — 6,864 0.9 % Latin America and Caribbean 11,320 24,092 46 — 35,458 4.5 % Japan 40,832 1,848 2,662 — 45,342 5.7 % Canada 3,267 995 130 — 4,392 0.6 % Rest of the world (b) 5,062 22,940 — — 28,002 3.5 % Sub-total, non United States 70,415 94,645 5,696 — 170,756 21.6 % Worldwide including United States (a) 56,169 24,005 29,937 — 110,111 13.9 % Other locations non-specific (c) 95,223 84,359 1 — 179,583 22.6 % Total $ 330,534 $ 360,057 $ 105,682 $ (3,371 ) $ 792,902 100.0 % Gross Premiums Written Six Months Ended June 30, 2018 Reinsurance Segment Insurance Segment Asset Management Segment Eliminations Total % United States $ 349,472 $ 748,975 $ 101,785 $ (1,525 ) $ 1,198,707 44.7 % Worldwide excluding United States (a) 52,287 93,662 2,777 — 148,726 5.6 % Australia and New Zealand 1,169 5,185 — — 6,354 0.2 % Europe 41,073 12,608 338 — 54,019 2.0 % Latin America and Caribbean 17,120 43,874 — — 60,994 2.3 % Japan 45,567 3,129 2,264 — 50,960 1.9 % Canada 8,690 1,864 359 — 10,913 0.4 % Rest of the world (b) 24,269 51,779 — — 76,048 2.9 % Sub-total, non United States 190,175 212,101 5,738 — 408,014 15.3 % Worldwide including United States (a) 178,068 57,444 277,640 (4,012 ) 509,140 19.0 % Other locations non-specific (c) 408,446 151,515 3,840 — 563,801 21.0 % Total $ 1,126,161 $ 1,170,035 $ 389,003 $ (5,537 ) $ 2,679,662 100.0 % Gross Premiums Written Six Months Ended June 30, 2017 Reinsurance Segment Insurance Segment Asset Management Segment Eliminations Total % United States $ 332,655 $ 347,236 $ 98,251 $ (3,371 ) $ 774,771 39.1 % Worldwide excluding United States (a) 40,586 69,833 7,905 — 118,324 5.9 % Australia and New Zealand 4,177 4,938 2,003 — 11,118 0.6 % Europe 33,113 14,392 451 — 47,956 2.4 % Latin America and Caribbean 21,280 44,779 46 — 66,105 3.3 % Japan 42,783 2,853 3,855 — 49,491 2.5 % Canada 5,625 1,444 130 — 7,199 0.4 % Rest of the world (b) 20,165 43,332 — — 63,497 3.2 % Sub-total, non United States 167,729 181,571 14,390 — 363,690 18.3 % Worldwide including United States (a) 151,970 51,192 153,246 — 356,408 18.0 % Other locations non-specific (c) 321,321 162,848 4,721 — 488,890 24.6 % Total $ 973,675 $ 742,847 $ 270,608 $ (3,371 ) $ 1,983,759 100.0 % (a) Represents risks in two or more geographic zones. (b) Represents risks in one geographic zone. (c) The other locations non-specific category refers to business for which an analysis of exposure by geographic zone is not applicable since these exposures can span multiple geographic areas and, in some instances, are not fixed locations.

Subsequent events

Subsequent events	6 Months Ended
	Jun. 30, 2018
Subsequent Events [Abstract]
Subsequent events	Subsequent events On July 18, 2018, the Company completed its previously announced Merger with AIG. Refer to Note 3 , “Business combinations,” for further details. On July 26, 2018, AIG executed a guarantee (the “Preference Shares Guarantee”) with respect to the Series A Preferred Shares and the Series B Preferred Shares of the Company. Under the terms of the Preference Shares Guarantee, AIG provided a full and unconditional guarantee of the Company’s obligations under the certificates of designation governing the Series A Preferred Shares and the Series B Preferred Shares, as applicable. Additionally on July 26, 2018, AIG executed a guarantee with respect to the Company’s aggregate outstanding 8.875% Senior Notes due 2040, pursuant to which AIG provided a full and unconditional guarantee of the Company’s obligations under the related indentures.

Significant accounting policies

Significant accounting policies (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of preparation	These unaudited Consolidated Financial Statements (the “Consolidated Financial Statements”) have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 in Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In addition, the year-end balance sheet data was derived from audited financial statements but does not include all disclosures required by U.S. GAAP. This Quarterly Report on Form 10-Q should be read in conjunction with the financial statements and related notes included in Validus Holdings, Ltd.’s (the “Company”) Annual Report on Form 10-K for the year ended December 31, 2017 , as filed with the U.S. Securities and Exchange Commission (the “SEC”). In the opinion of management, these unaudited Consolidated Financial Statements reflect all adjustments (including normal recurring adjustments) considered necessary for a fair statement of the Company’s financial position and results of operations as at the end of and for the periods presented. All significant intercompany accounts and transactions have been eliminated. The results of operations for any interim period are not necessarily indicative of the results for a full year.
Use of estimates	The preparation of these Consolidated Financial Statements in conformity with U.S. 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. While the amounts included in the Consolidated Financial Statements reflect management’s best estimates and assumptions, actual results could differ from those estimates. The Company’s principal estimates include: • the reserve for losses and loss expenses; • the premium written on a line slip or proportional basis; • the valuation of goodwill and intangible assets; • the loss reserves recoverable, including the provision for uncollectible amounts; and • the valuation of invested assets and other financial instruments.
Consolidating voting interest entities and variable interest entities	The Company consolidates in these Consolidated Financial Statements the results of operations and financial position of every voting interest entity (“VOE”) in which the Company has a controlling financial interest and variable interest entity (“VIE”) in which the Company is considered to be the primary beneficiary. The consolidation assessment, including the determination as to whether an entity qualifies as a VIE or VOE, depends on the facts and circumstances surrounding each entity.

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2018
Investments [Abstract]
Amortized cost (or cost), gross unrealized gains and (losses) and fair value of investments	The amortized cost (or cost) and fair values of the Company’s investments as at June 30, 2018 and December 31, 2017 were as follows: June 30, 2018 December 31, 2017 Amortized Cost or Cost Fair Value Amortized Fair Value Managed investments U.S. government and government agency $ 613,130 $ 604,392 $ 733,510 $ 727,397 Non-U.S. government and government agency 285,514 282,263 310,845 312,239 U.S. states, municipalities and political subdivisions 191,065 189,437 201,347 201,303 Agency residential mortgage-backed securities 956,254 929,859 984,387 978,049 Non-agency residential mortgage-backed securities 48,061 47,600 40,264 40,373 U.S. corporate 1,459,190 1,436,885 1,531,498 1,533,395 Non-U.S. corporate 410,287 403,385 420,522 422,249 Bank loans 480,593 471,212 450,320 442,951 Asset-backed securities 719,803 714,434 657,234 658,303 Commercial mortgage-backed securities 309,080 301,544 315,002 312,395 Total fixed maturities 5,472,977 5,381,011 5,644,929 5,628,654 Short-term investments 218,071 218,035 229,968 230,011 Other investments Hedge funds 6,954 15,888 6,954 15,774 Private equity investments 64,921 79,185 63,684 78,407 Fixed income investment funds 208,400 209,503 203,167 204,426 Overseas deposits 61,608 61,608 56,611 56,611 Total other investments 341,883 366,184 330,416 355,218 Investments in investment affiliates (a) 72,135 127,247 61,944 100,137 Total managed investments $ 6,105,066 $ 6,092,477 $ 6,267,257 $ 6,314,020 Non-managed investments Catastrophe bonds $ 178,976 $ 178,942 $ 231,332 $ 229,694 Short-term investments 3,510,859 3,510,859 3,151,746 3,151,746 Total non-managed investments 3,689,835 3,689,801 3,383,078 3,381,440 Total investments $ 9,794,901 $ 9,782,278 $ 9,650,335 $ 9,695,460 (a) The Company’s investments in investment affiliates have been treated as equity method investments with the corresponding gains and losses recorded in income as “Income from investment affiliates.”
Investment ratings on fixed maturities	The following table sets forth certain information regarding Standard & Poor’s credit quality ratings (or an equivalent rating with another recognized rating agency) of the Company’s fixed maturity investments as at June 30, 2018 and December 31, 2017 : June 30, 2018 December 31, 2017 Fair Value % of Total Fair Value % of Total Managed fixed maturities AAA $ 2,560,857 46.2 % $ 2,715,074 46.4 % AA 417,814 7.5 % 442,397 7.6 % A 1,102,419 19.8 % 1,137,795 19.4 % BBB 797,698 14.3 % 828,392 14.1 % Total investment grade managed fixed maturities 4,878,788 87.8 % 5,123,658 87.5 % BB 157,241 2.8 % 168,967 2.9 % B 227,954 4.1 % 237,131 4.0 % CCC 20,219 0.4 % 18,217 0.3 % CC 564 — % — — % NR 96,245 1.7 % 80,681 1.4 % Total non-investment grade managed fixed maturities 502,223 9.0 % 504,996 8.6 % Total managed fixed maturities $ 5,381,011 96.8 % $ 5,628,654 96.1 % Non-managed catastrophe bonds AAA $ 250 — % $ — — % Total investment grade non-managed catastrophe bonds 250 — % — — % BB $ 6,632 0.2 % $ 22,110 0.3 % B 2,626 — % 3,265 0.1 % NR 169,434 3.0 % 204,319 3.5 % Total non-investment grade non-managed catastrophe bonds 178,692 3.2 % 229,694 3.9 % Total non-managed catastrophe bonds 178,942 3.2 % 229,694 3.9 % Total fixed maturities $ 5,559,953 100.0 % $ 5,858,348 100.0 %
Fixed maturities investments by contractual maturity	The amortized cost and fair values for the Company’s fixed maturity investments held at June 30, 2018 and December 31, 2017 are shown below by contractual maturity. Actual maturity may differ from contractual maturity due to prepayment rights associated with certain investments. June 30, 2018 December 31, 2017 Amortized Cost or Cost Fair Value Amortized Cost or Cost Fair Value Managed fixed maturities Due in one year or less $ 361,061 $ 359,094 $ 343,360 $ 343,541 Due after one year through five years 2,333,731 2,295,728 2,527,018 2,513,620 Due after five years through ten years 556,784 547,685 577,347 577,109 Due after ten years 188,203 185,067 200,317 205,264 3,439,779 3,387,574 3,648,042 3,639,534 Asset-backed and mortgage-backed securities 2,033,198 1,993,437 1,996,887 1,989,120 Total managed fixed maturities $ 5,472,977 $ 5,381,011 $ 5,644,929 $ 5,628,654 Non-managed catastrophe bonds Due in one year or less $ 47,918 $ 46,922 $ 88,797 $ 88,367 Due after one year through five years 130,433 131,395 140,035 138,844 Due after five years through ten years 625 625 2,500 2,483 Total non-managed catastrophe bonds 178,976 178,942 231,332 229,694 Total fixed maturities $ 5,651,953 $ 5,559,953 $ 5,876,261 $ 5,858,348
Other investments	The following tables set forth certain information regarding the Company’s other investment portfolio as at June 30, 2018 and December 31, 2017 : June 30, 2018 Fair Value Investments with redemption restrictions Investments without redemption restrictions Redemption frequency (a) Redemption notice period (a) Hedge funds $ 15,888 $ 15,888 $ — Private equity investments 79,185 79,185 — Fixed income investment funds 209,503 209,503 — Overseas deposits 61,608 61,608 — Total other investments $ 366,184 $ 366,184 $ — December 31, 2017 Fair Value Investments with redemption restrictions Investments without redemption restrictions Redemption frequency (a) Redemption notice period (a) Hedge funds 15,774 15,774 — Private equity investments 78,407 78,407 — Fixed income investment funds 204,426 200,532 3,894 Daily Daily to 2 days Overseas deposits 56,611 56,611 — Total other investments $ 355,218 $ 351,324 $ 3,894 (a) The redemption frequency and notice periods only apply to investments without redemption restrictions.
Reconciliation of beginning and ending investment in affiliate balances	The following table presents a reconciliation of the Company’s beginning and ending investments in investment affiliates for three and six months ended June 30, 2018 and 2017 : Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Investment affiliates, beginning of period $ 113,471 $ 94,697 $ 100,137 $ 100,431 Net capital contributions (distributions) 11,598 (786 ) 11,864 (11,708 ) Income from investment affiliates 2,178 9,466 15,246 14,654 Investment affiliates, end of period $ 127,247 $ 103,377 $ 127,247 $ 103,377
Schedule of equity method investments	The following table presents the Company’s investments in the Aquiline partnerships as at June 30, 2018 and December 31, 2017 : June 30, 2018 Investment at cost Voting ownership % Equity ownership % Carrying value Aquiline II $ 28,529 — % 8.1 % $ 49,248 Aquiline III 25,501 — % 9.0 % 59,900 Aquiline Tech 4,406 — % 10.6 % 4,400 Aquiline Armour 13,699 — % 15.2 % 13,699 Total investments in investment affiliates $ 72,135 $ 127,247 December 31, 2017 Investment at cost Voting ownership % Equity ownership % Carrying value Aquiline II $ 33,349 — % 8.1 % $ 51,914 Aquiline III 24,737 — % 9.0 % 44,733 Aquiline Tech 3,858 — % 10.6 % 3,490 Total investments in investment affiliates $ 61,944 $ 100,137
Net investment income	Net investment income was derived from the following sources: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Managed investments Fixed maturities and short-term investments $ 39,224 $ 31,212 $ 76,993 $ 62,883 Other investments 4,846 7,571 9,069 14,441 Cash and cash equivalents and restricted cash 1,744 716 2,883 1,326 Securities lending income 4 7 7 20 Total gross investment income 45,818 39,506 88,952 78,670 Investment expenses (3,066 ) (1,443 ) (6,409 ) (4,415 ) Total managed net investment income $ 42,752 $ 38,063 $ 82,543 $ 74,255 Non managed investments Fixed maturities and short-term investments $ 5,842 $ 4,500 $ 9,990 $ 7,560 Cash and cash equivalents and restricted cash 8,966 1,678 17,099 2,640 Total non-managed net investment income 14,808 6,178 27,089 10,200 Total net investment income $ 57,560 $ 44,241 $ 109,632 $ 84,455
Analysis of net realized gains and the change in net unrealized gains (losses) on investments	The following table sets forth an analysis of net realized (losses) gains and the change in net unrealized gains and losses on investments: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Managed investments Gross realized gains $ 3,048 $ 5,175 $ 9,878 $ 7,865 Gross realized (losses) (10,480 ) (2,906 ) (16,168 ) (8,488 ) Net realized (losses) gains on investments (7,432 ) 2,269 (6,290 ) (623 ) Change in net unrealized (losses) gains on investments (11,392 ) 15,942 (68,169 ) 30,291 Total net realized and change in net unrealized (losses) gains on managed investments $ (18,824 ) $ 18,211 $ (74,459 ) $ 29,668 Non-managed investments Gross realized gains $ 175 $ 5 $ 1,410 $ 1,733 Gross realized (losses) (137 ) — (314 ) — Net realized gains on investments 38 5 1,096 1,733 Change in net unrealized gains (losses) on investments 662 379 58 (622 ) Total net realized and change in net unrealized gains on non-managed investments 700 384 1,154 1,111 Total net realized and change in net unrealized (losses) gains on total investments $ (18,124 ) $ 18,595 $ (73,305 ) $ 30,779

Fair value measurements (Tables

Fair value measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair value hierarchy - allocation of investments	At June 30, 2018 , the Company’s investments were allocated between Levels 1, 2 and 3 as follows: Level 1 Level 2 Level 3 Fair value based on NAV practical expedient (a) Total Managed investments U.S. government and government agency $ — $ 604,392 $ — $ — $ 604,392 Non-U.S. government and government agency — 282,263 — — 282,263 U.S. states, municipalities and political subdivisions — 189,437 — — 189,437 Agency residential mortgage-backed securities — 929,859 — — 929,859 Non-agency residential mortgage-backed securities — 47,600 — — 47,600 U.S. corporate — 1,436,885 — — 1,436,885 Non-U.S. corporate — 403,385 — — 403,385 Bank loans — 245,476 225,736 — 471,212 Asset-backed securities — 613,169 101,265 — 714,434 Commercial mortgage-backed securities — 301,544 — — 301,544 Total fixed maturities — 5,054,010 327,001 — 5,381,011 Short-term investments 187,231 30,804 — — 218,035 Other investments Hedge funds — — — 15,888 15,888 Private equity investments — — — 79,185 79,185 Fixed income investment funds — 9,576 18,807 181,120 209,503 Overseas deposits — — — 61,608 61,608 Total other investments — 9,576 18,807 337,801 366,184 Investments in investment affiliates (b) — — — — 127,247 Total managed investments $ 187,231 $ 5,094,390 $ 345,808 $ 337,801 $ 6,092,477 Non-managed investments Catastrophe bonds $ — $ 127,380 $ 51,562 $ — $ 178,942 Short-term investments 3,510,859 — — — 3,510,859 Total non-managed investments 3,510,859 127,380 51,562 — 3,689,801 Total investments $ 3,698,090 $ 5,221,770 $ 397,370 $ 337,801 $ 9,782,278 (a) In accordance with ASC Topic 820 “Fair Value Measurements,” investments measured at fair value using the net asset value (“NAV”) per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. (b) In accordance with ASC Topic 825 “Financial Instruments,” the Company’s investments in investment affiliates have not been classified in the fair value hierarchy. At December 31, 2017 , the Company’s investments were allocated between Levels 1, 2 and 3 as follows: Level 1 Level 2 Level 3 Fair value based on NAV practical expedient (a) Total Managed investments U.S. government and government agency $ — $ 727,397 $ — $ — $ 727,397 Non-U.S. government and government agency — 312,239 — — 312,239 U.S. states, municipalities and political subdivisions — 201,303 — — 201,303 Agency residential mortgage-backed securities — 978,049 — — 978,049 Non-agency residential mortgage-backed securities — 40,373 — — 40,373 U.S. corporate — 1,533,395 — — 1,533,395 Non-U.S. corporate — 422,249 — — 422,249 Bank loans — 232,886 210,065 — 442,951 Asset-backed securities — 554,490 103,813 — 658,303 Commercial mortgage-backed securities — 312,395 — — 312,395 Total fixed maturities — 5,314,776 313,878 — 5,628,654 Short-term investments 198,054 31,957 — — 230,011 Other investments Hedge funds — — — 15,774 15,774 Private equity investments — — — 78,407 78,407 Fixed income investment funds — 13,351 17,404 173,671 204,426 Overseas deposits — — — 56,611 56,611 Total other investments — 13,351 17,404 324,463 355,218 Investments in investment affiliates (b) — — — — 100,137 Total managed investments $ 198,054 $ 5,360,084 $ 331,282 $ 324,463 $ 6,314,020 Non-managed investments Catastrophe bonds $ — $ 152,233 $ 77,461 $ — $ 229,694 Short-term investments 3,151,746 — — — 3,151,746 Total non-managed investments 3,151,746 152,233 77,461 — 3,381,440 Total investments $ 3,349,800 $ 5,512,317 $ 408,743 $ 324,463 $ 9,695,460 (a) In accordance with ASC Topic 820 “Fair Value Measurements,” investments measured at fair value using the net asset value (“NAV”) per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. (b) In accordance with ASC Topic 825 “Financial Instruments,” the Company’s investments in investment affiliates have not been classified in the fair value hierarchy.
Reconciliation of beginning and ending balances for all Level 3 investments measured at fair value on recurring basis	The following table presents a reconciliation of the beginning and ending balances for all investments measured at fair value on a recurring basis using Level 3 inputs during the three and six months ended June 30, 2018 and 2017 : Three Months Ended June 30, 2018 Bank Loans Catastrophe Bonds Fixed Income Investment Funds Asset Backed Securities Total Level 3 investments, beginning of period $ 227,503 $ 65,697 $ 17,933 $ 101,816 $ 412,949 Purchases 14,422 — 874 — 15,296 Sales — — — (70 ) (70 ) Settlements (14,698 ) (15,001 ) — — (29,699 ) Change in net unrealized (losses) gains (1,491 ) 866 — (481 ) (1,106 ) Level 3 investments, end of period $ 225,736 $ 51,562 $ 18,807 $ 101,265 $ 397,370 Three Months Ended June 30, 2017 Bank Loans Catastrophe Bonds Fixed Income Investment Funds Asset Backed Securities Total Level 3 investments, beginning of period $ 236,694 $ 72,676 $ 12,560 $ 23,882 $ 345,812 Purchases 16,757 5,000 3,432 11,053 36,242 Sales — — — (53 ) (53 ) Settlements (28,893 ) (10,216 ) 408 — (38,701 ) Realized gains — 216 — — 216 Change in net unrealized (losses) gains (386 ) 349 — 1,039 1,002 Level 3 investments, end of period $ 224,172 $ 68,025 $ 16,400 $ 35,921 $ 344,518 Six Months Ended June 30, 2018 Bank Loans Catastrophe Bonds Fixed Income Investment Funds Asset Backed Securities Total Level 3 investments, beginning of period $ 210,065 $ 77,461 $ 17,404 $ 103,813 $ 408,743 Purchases 45,207 18,825 1,403 — 65,435 Sales — — — (140 ) (140 ) Settlements (28,540 ) (46,485 ) — — (75,025 ) Realized gains — 1,235 — — 1,235 Change in net unrealized (losses) gains (996 ) 526 — (2,408 ) (2,878 ) Level 3 investments, end of period $ 225,736 $ 51,562 $ 18,807 $ 101,265 $ 397,370 Six Months Ended June 30, 2017 Bank Loans Catastrophe Bonds Fixed Income Investment Funds Asset Backed Securities Total Level 3 investments, beginning of period $ 246,496 $ 48,375 $ 12,168 $ 23,931 $ 330,970 Purchases 39,933 66,091 3,432 11,053 120,509 Sales — — — (53 ) (53 ) Settlements (62,003 ) (48,996 ) 800 — (110,199 ) Realized gains — 3,350 — — 3,350 Change in net unrealized (losses) gains (254 ) (795 ) — 990 (59 ) Level 3 investments, end of period $ 224,172 $ 68,025 $ 16,400 $ 35,921 $ 344,518

Variable interest entities (Tab

Variable interest entities (Tables)	6 Months Ended
	Jun. 30, 2018
Variable Interest Entities Disclosure [Abstract]
Summary of notes payable to variable interest entities	The following tables present reconciliations of the beginning and ending notes payable to AlphaCat investors during the three and six months ended June 30, 2018 and 2017 : Three Months Ended June 30, 2018 Variable Funding Notes Structured Notes Total Notes payable to AlphaCat investors, beginning of period $ 916,022 $ 352,172 $ 1,268,194 Issuance of notes payable to AlphaCat investors 305,039 280 305,319 Redemption of notes payable to AlphaCat investors (362,565 ) — (362,565 ) Foreign exchange gains (4,277 ) — (4,277 ) Notes payable to AlphaCat investors, end of period $ 854,219 $ 352,452 $ 1,206,671 Three Months Ended June 30, 2017 Variable Funding Notes Structured Notes Total Notes payable to AlphaCat investors, beginning of period $ 343,256 $ 103,320 $ 446,576 Notes payable to AlphaCat investors recognized on deconsolidation of AlphaCat ILS fund 423,269 — 423,269 Issuance of notes payable to AlphaCat investors 267,867 68,880 336,747 Redemption of notes payable to AlphaCat investors (140,150 ) — (140,150 ) Foreign exchange gains (283 ) — (283 ) Notes payable to AlphaCat investors, end of period $ 893,959 $ 172,200 $ 1,066,159 Six Months Ended June 30, 2018 Variable Funding Notes Structured Notes Total Notes payable to AlphaCat investors, beginning of period $ 936,164 $ 172,200 $ 1,108,364 Issuance of notes payable to AlphaCat investors 811,579 180,252 991,831 Redemption of notes payable to AlphaCat investors (893,111 ) — (893,111 ) Foreign exchange gains (413 ) — (413 ) Notes payable to AlphaCat investors, end of period $ 854,219 $ 352,452 $ 1,206,671 Six Months Ended June 30, 2017 Variable Funding Notes Structured Notes Total Notes payable to AlphaCat investors, beginning of period $ 278,202 $ — $ 278,202 Notes payable to AlphaCat investors recognized on deconsolidation of AlphaCat ILS fund 423,269 — 423,269 Issuance of notes payable to AlphaCat investors 541,877 172,200 714,077 Redemption of notes payable to AlphaCat investors (349,106 ) — (349,106 ) Foreign exchange gains (283 ) — (283 ) Notes payable to AlphaCat investors, end of period $ 893,959 $ 172,200 $ 1,066,159
Total assets and liabilities of the Company's consolidated VIEs	The following table presents the total assets and total liabilities of the Company’s consolidated VIEs, excluding intercompany eliminations, as at June 30, 2018 and December 31, 2017 : June 30, 2018 December 31, 2017 Total Assets Total Liabilities Total Assets Total Liabilities AlphaCat sidecars $ 15,647 $ 3,102 $ 25,975 $ 3,267 AlphaCat ILS funds - Lower Risk 1,205,476 86,339 1,107,503 259,630 AlphaCat ILS funds - Higher Risk 1,162,492 383,231 1,310,071 912,341 AlphaCat Re and AlphaCat Master Fund 3,830,442 3,830,272 3,398,082 3,397,912 BetaCat ILS funds 89,161 210 77,221 261

Noncontrolling interest (Tables

Noncontrolling interest (Tables)	6 Months Ended
	Jun. 30, 2018
Noncontrolling Interest [Abstract]
Reconciliation of beginning and ending balances of noncontrolling interest and redeemable noncontrolling interest	The following tables present a reconciliation of the beginning and ending balances of redeemable noncontrolling interests and noncontrolling interests for the three and six months ended June 30, 2018 and 2017 : Redeemable Noncontrolling Interests Total Three Months Ended June 30, Three Months Ended June 30, Three Months Ended June 30, 2018 2017 2018 2017 2018 2017 Balance, beginning of period $ 1,423,110 $ 1,657,630 $ 334,357 $ 330,597 $ 1,757,467 $ 1,988,227 Issuance of shares 81,250 106,501 40,600 103,320 121,850 209,821 Adjustment to noncontrolling interests as a result of deconsolidation — (459,021 ) — — — (459,021 ) Income attributable to noncontrolling interests 19,255 28,555 16,256 15,095 35,511 43,650 Redemption of shares / Distributions (133,382 ) (82,005 ) (19,956 ) (33,354 ) (153,338 ) (115,359 ) Balance, end of period $ 1,390,233 $ 1,251,660 $ 371,257 $ 415,658 $ 1,761,490 $ 1,667,318 Redeemable Noncontrolling Interests Total Six Months Ended June 30, Six Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 2018 2017 Balance, beginning of period $ 1,004,094 $ 1,528,001 $ 16,718 $ 165,977 $ 1,020,812 $ 1,693,978 Issuance of shares 466,550 210,200 321,900 258,300 788,450 468,500 Adjustment to noncontrolling interests as a result of deconsolidation — (459,021 ) — — — (459,021 ) Income attributable to noncontrolling interests 47,628 54,485 52,595 31,737 100,223 86,222 Redemption of shares / Distributions (128,039 ) (82,005 ) (19,956 ) (40,356 ) (147,995 ) (122,361 ) Balance, end of period $ 1,390,233 $ 1,251,660 $ 371,257 $ 415,658 $ 1,761,490 $ 1,667,318

Derivative instruments (Tables)

Derivative instruments (Tables)	6 Months Ended
	Jun. 30, 2018
Not designated as hedging instruments
Derivative [Line Items]
Location and fair value amount of derivative instruments reported on the balance sheet	The following tables summarize information on the classification and amount of the fair value of derivatives not designated as hedging instruments within the Company’s Consolidated Balance Sheets as at June 30, 2018 and December 31, 2017 : June 30, 2018 December 31, 2017 Derivatives not designated as hedging instruments Notional Exposure Asset Derivative at Fair Value (a) Liability Derivative at Fair Value (a) Notional Exposure Asset Derivative at Fair Value (a) Liability Derivative at Fair Value (a) Foreign currency forward contracts $ 190,952 $ 3,880 $ 3,310 $ 283,765 $ 1,147 $ 906 Interest rate swap contracts $ 200,000 $ 10,306 $ — $ 200,000 $ 1,589 $ — Weather derivative contracts $ 4,825 $ 8,380 $ — $ 4,825 $ 853 $ — (a) Asset and liability derivative positions are classified within other assets and accounts payable and accrued expenses, respectively, within the Company’s Consolidated Balance Sheets.
Location and amount of gains and losses related to derivative instruments reported on in the income statement	The following table summarizes information on the classification and net impact on earnings recognized in the Company’s Consolidated Statements of (Loss) Income and Comprehensive (Loss) Income relating to derivatives that were not designated as hedging instruments during the three and six months ended June 30, 2018 and 2017 : Derivatives not designated as hedging instruments Classification of gains recognized in earnings Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Foreign currency forward contracts Foreign exchange (losses) gains $ 4,843 $ (6,525 ) $ (358 ) $ (6,072 ) Foreign currency forward contracts Other insurance related income and other income $ — $ (874 ) $ — $ (979 ) Interest rate swap contracts Net realized gains on investments $ 2,123 $ (319 ) $ 8,067 $ (319 ) Weather derivative contracts Other insurance related income and other income $ (17,910 ) $ — $ 8,863 $ —
Designated as hedging instruments
Derivative [Line Items]
Location and fair value amount of derivative instruments reported on the balance sheet	The following table summarizes information on the classification and amount of the fair value of derivatives designated as hedging instruments on the Consolidated Balance Sheets as at June 30, 2018 and December 31, 2017 : June 30, 2018 December 31, 2017 Derivatives designated as hedging instruments Notional Exposure Asset Derivative at Fair Value (a) Liability Derivative at Fair Value (a) Notional Exposure Asset Derivative at Fair Value (a) Liability Derivative at Fair Value (a) Interest rate swap contracts $ 552,263 $ 28,982 $ 2,627 $ 552,263 $ 9,806 $ 18,840 Foreign currency forward contracts $ 64,405 $ — $ 546 $ 96,293 $ 1,891 $ — (a) Asset and liability derivative positions are classified within other assets and accounts payable and accrued expenses, respectively, within the Company’s Consolidated Balance Sheets
Location and amount of gains and losses related to derivative instruments reported on in the income statement	The following tables provide the total impact on other comprehensive income and earnings relating to the derivative instruments formally designated as cash flow hedges for the three and six months ended June 30, 2018 and 2017 : Three Months Ended June 30, Six Months Ended June 30, Interest rate swap contracts 2018 2017 2018 2017 Amount recognized in other comprehensive income $ 7,200 $ (144 ) $ 33,043 $ (46 ) Amount reclassified to finance expenses $ 698 $ — $ 2,041 $ — Three Months Ended June 30, Six Months Ended June 30, Foreign currency forward contracts 2018 2017 2018 2017 Amount recognized in other comprehensive income $ (4,165 ) $ — $ (1,245 ) $ — Amount reclassified to general and administrative expenses $ (884 ) $ — $ (1,192 ) $ —

Reserve for losses and loss e32

Reserve for losses and loss expenses (Tables)	6 Months Ended
	Jun. 30, 2018
Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract]
Summary of reserve for losses and loss expenses	The following table summarizes the Company’s reserve for losses and loss expenses as at June 30, 2018 and December 31, 2017 : June 30, 2018 December 31, 2017 Case reserves $ 1,836,130 $ 1,753,844 IBNR 2,863,469 3,077,546 Reserve for losses and loss expenses $ 4,699,599 $ 4,831,390
Reserve for losses and loss expenses	The following table represents an analysis of paid and unpaid losses and loss expenses incurred and a reconciliation of the beginning and ending unpaid losses and loss expenses for the three and six months ended June 30, 2018 and 2017 : Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Reserve for losses and loss expenses, beginning of period $ 4,632,629 $ 3,052,745 $ 4,831,390 $ 2,995,195 Loss reserves recoverable (979,944 ) (451,856 ) (1,233,997 ) (430,421 ) Net reserves for losses and loss expenses, beginning of period 3,652,685 2,600,889 3,597,393 2,564,774 Net reserves acquired — 23,753 — 23,753 Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in: Current year 489,181 339,439 818,296 670,255 Prior years (12,571 ) (43,290 ) (20,141 ) (104,521 ) Total incurred losses and loss expenses 476,610 296,149 798,155 565,734 Foreign exchange (gain) loss (30,348 ) 20,216 (14,721 ) 32,533 Less net losses and loss expenses paid in respect of losses occurring in: Current year (61,340 ) (42,758 ) (81,075 ) (50,456 ) Prior years (308,958 ) (193,265 ) (571,103 ) (431,354 ) Total net paid losses (370,298 ) (236,023 ) (652,178 ) (481,810 ) Net reserve for losses and loss expenses, end of period 3,728,649 2,704,984 3,728,649 2,704,984 Loss reserves recoverable 970,950 600,207 970,950 600,207 Reserve for losses and loss expenses, end of period $ 4,699,599 $ 3,305,191 $ 4,699,599 $ 3,305,191 Incurred losses and loss expenses comprise: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Gross losses and loss expenses $ 535,438 $ 410,421 $ 784,219 $ 746,863 Reinsurance recoveries (58,828 ) (114,272 ) 13,936 (181,129 ) Net incurred losses and loss expenses $ 476,610 $ 296,149 $ 798,155 $ 565,734
Prior year development by segment and line of business	The net (favorable) adverse development on prior accident years by segment and line of business for the three and six months ended June 30, 2018 and 2017 was as follows: Three Months Ended June 30, 2018 Property Specialty - Short-tail Specialty - Other Total Reinsurance Segment $ (9,634 ) $ (10,273 ) $ 5,097 $ (14,810 ) Insurance Segment 4,792 4,986 (4,814 ) 4,964 Asset Management Segment (1,666 ) (1,059 ) — (2,725 ) Net (favorable) adverse development $ (6,508 ) $ (6,346 ) $ 283 $ (12,571 ) Three Months Ended June 30, 2017 Property Specialty - Short-tail Specialty - Other Total Reinsurance Segment $ (697 ) $ (14,344 ) $ (667 ) $ (15,708 ) Insurance Segment (5,347 ) (9,349 ) (9,034 ) (23,730 ) Asset Management Segment (3,097 ) (755 ) — (3,852 ) Net favorable development $ (9,141 ) $ (24,448 ) $ (9,701 ) $ (43,290 ) The net favorable development on prior accident years for the three months ended June 30, 2018 and 2017 was primarily driven by favorable development on attritional losses. Six Months Ended June 30, 2018 Property Specialty - Short-tail Specialty - Other Total Reinsurance Segment $ (14,456 ) $ (23,724 ) $ 5,532 $ (32,648 ) Insurance Segment 8,860 (7,215 ) (12,229 ) (10,584 ) Asset Management Segment 23,534 (443 ) — 23,091 Net adverse (favorable) development $ 17,938 $ (31,382 ) $ (6,697 ) $ (20,141 ) Six Months Ended June 30, 2017 Property Specialty - Short-tail Specialty - Other Total Reinsurance Segment $ (4,759 ) $ (41,092 ) $ (981 ) $ (46,832 ) Insurance Segment (14,013 ) (21,112 ) (15,294 ) (50,419 ) Asset Management Segment (7,492 ) 222 — (7,270 ) Net favorable development $ (26,264 ) $ (61,982 ) $ (16,275 ) $ (104,521 ) The net favorable development on prior accident years for the six months ended June 30, 2018 and 2017 was primarily driven by favorable development on attritional losses.

Reinsurance (Tables)

Reinsurance (Tables)	6 Months Ended
	Jun. 30, 2018
Reinsurance Disclosures [Abstract]
Schedule of reinsurance recoverable	The Company’s reinsurance balances recoverable at June 30, 2018 and December 31, 2017 were as follows: June 30, 2018 December 31, 2017 Loss reserves recoverable on unpaid: Case reserves $ 287,141 $ 275,450 IBNR 683,809 958,547 Total loss reserves recoverable 970,950 1,233,997 Paid losses recoverable 71,876 46,873 Total reinsurance recoverable $ 1,042,826 $ 1,280,870
Reinsurance recoverables by reinsurer	Information regarding the Company’s concentration of credit risk arising from its exposure to individual reinsurers as at June 30, 2018 and December 31, 2017 is as follows: June 30, 2018 December 31, 2017 Reinsurance Recoverable % of Total Reinsurance Recoverable % of Total Top 10 reinsurers $ 857,819 82.2 % $ 1,055,445 82.5 % Other reinsurers’ balances > $1 million 176,212 17.0 % 218,226 17.0 % Other reinsurers’ balances < $1 million 8,795 0.8 % 7,199 0.5 % Total $ 1,042,826 100.0 % $ 1,280,870 100.0 % June 30, 2018 Top 10 Reinsurers Rating Reinsurance Recoverable % of Total Fully collateralized reinsurers NR $ 400,415 38.4 % Everest Re A+ 120,146 11.5 % Lloyd's Syndicates A+ 75,841 7.3 % Swiss Re AA- 49,857 4.8 % Munich Re AA- 46,444 4.5 % Hannover Re AA- 46,353 4.4 % Transatlantic Re A+ 43,050 4.1 % Qatar Insurance Company A 31,107 3.0 % Partner Re A+ 23,283 2.2 % Markel A 21,323 2.0 % Total $ 857,819 82.2 % NR: Not rated December 31, 2017 Top 10 Reinsurers Rating Reinsurance Recoverable % of Total Fully collateralized reinsurers NR $ 459,339 35.9 % Everest Re A+ 128,206 10.0 % Munich Re AA- 94,180 7.4 % Lloyd's Syndicates A+ 74,277 5.8 % Federal Crop Insurance Corporation (a) 68,745 5.4 % Swiss Re AA- 65,218 5.1 % Hannover Re AA- 53,523 4.2 % Qatar Insurance Company A 50,160 3.9 % Transatlantic Re A+ 33,729 2.6 % Markel A 28,068 2.2 % Total $ 1,055,445 82.5 % NR: Not rated (a) The Company participates in a crop reinsurance program sponsored by the U.S. federal government. The Company remains obligated for amounts ceded in the event that its reinsurers or retrocessionaires do not meet their obligations, except for amounts ceded to the U.S. federal government in the Insurance segment agriculture line of business.

Share capital (Tables)

Share capital (Tables)	6 Months Ended
	Jun. 30, 2018
Stockholders' Equity Note [Abstract]
Summary of common shares issued and outstanding	The following table is a summary of the common shares issued and outstanding during the six months ended June 30, 2018 and 2017 : Six Months Ended June 30, 2018 2017 Common shares issued, beginning of period 161,994,491 161,279,976 Restricted share awards vested, net of shares withheld 1,015,069 597,021 Restricted share units vested, net of shares withheld 63,702 14,948 Performance shares vested, net of shares withheld 113,627 42,410 Common shares issued, end of period 163,186,889 161,934,355 Treasury shares, end of period (82,674,941 ) (82,415,774 ) Common shares outstanding, end of period 80,511,948 79,518,581

Stock plans (Tables)

Stock plans (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Options, activity during the period	Activity with respect to options for the six months ended June 30, 2017 was as follows: Options Weighted Average Grant Date Fair Value Weighted Average Grant Date Exercise Price Options outstanding, beginning and end of period 26,136 $ 6.78 $ 23.48
Restricted shares awards, activity during the period	Activity with respect to unvested restricted share awards for the six months ended June 30, 2018 and 2017 was as follows: Six Months Ended June 30, 2018 2017 Restricted Share Awards Weighted Average Grant Date Fair Value Restricted Share Awards Weighted Average Grant Date Fair Value Restricted share awards outstanding, beginning of period 2,080,397 $ 43.66 2,469,982 $ 40.89 Restricted share awards granted 1,552 67.64 481,619 53.42 Restricted share awards vested (1,322,774 ) 40.13 (803,764 ) 41.31 Restricted share awards forfeited (15,985 ) 47.32 (39,617 ) 41.98 Restricted share awards outstanding, end of period 743,190 $ 49.92 2,108,220 $ 43.58
Restricted share units, activity during the period	Activity with respect to unvested restricted share units for the six months ended June 30, 2018 and 2017 was as follows: Six Months Ended June 30, 2018 2017 Restricted Share Units Weighted Average Grant Date Fair Value Restricted Share Units Weighted Average Grant Date Fair Value Restricted share units outstanding, beginning of period 109,394 $ 42.20 112,808 $ 40.95 Restricted share units granted — — 12,236 53.40 Restricted share units vested (81,139 ) 39.27 (18,241 ) 41.66 Restricted share units issued in lieu of cash dividends 2,105 42.25 1,468 40.98 Restricted share units forfeited (17 ) 44.63 — — Restricted share units outstanding, end of period 30,343 $ 50.04 108,271 $ 42.24
Performance share awards, activity during the period	Activity with respect to unvested performance share awards for the six months ended June 30, 2018 and 2017 was as follows: Six Months Ended June 30, 2018 2017 Performance Share Awards Weighted Average Grant Date Fair Value Performance Share Awards Weighted Average Grant Date Fair Value Performance share awards outstanding, beginning of period 314,068 $ 49.37 285,820 $ 44.53 Performance share awards granted — — 107,209 53.40 Performance share awards vested (142,749 ) 45.03 (52,639 ) 37.33 Performance share awards conversion adjustment 235,564 49.37 (26,322 ) 36.82 Performance share awards outstanding, end of period 406,883 $ 50.89 314,068 $ 49.37
Total share compensation expenses	The breakdown of share compensation expenses by award type for the periods indicated was as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Restricted share awards $ 7,190 $ 9,745 $ 15,303 $ 18,789 Restricted share units 284 327 616 642 Performance share awards 8,566 1,074 9,850 1,206 Total $ 16,040 $ 11,146 $ 25,769 $ 20,637

Debt and financing arrangemen36

Debt and financing arrangements (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Summary of outstanding debentures and senior notes payable	The Company’s outstanding debentures and senior notes payable as at June 30, 2018 and December 31, 2017 were as follows: June 30, 2018 December 31, 2017 Deferrable debentures 2006 Junior Subordinated $ 150,000 $ 150,000 2007 Junior Subordinated 139,800 139,800 Flagstone 2006 Junior Subordinated 135,201 135,608 Flagstone 2007 Junior Subordinated 113,750 113,750 Total debentures payable 538,751 539,158 2010 Senior Notes due 2040 250,000 250,000 Less: Unamortized debt issuance costs (4,336 ) (4,436 ) Total senior notes payable 245,664 245,564 Total debentures and senior notes payable $ 784,415 $ 784,722
Summary of key terms of debentures and senior notes	The following table summarizes the key terms of the Company’s Senior Notes and Junior Subordinated deferrable debentures: Description Issuance date Issued Maturity date Interest Rate as at Interest payments due Issuance Date June 30, 2018 2006 Junior Subordinated Deferrable Debentures June 15, 2006 $ 150,000 June 15, 2036 9.069 % (a) 5.831 % (e) Quarterly Flagstone 2006 Junior Subordinated Deferrable Debentures August 23, 2006 $ 135,201 September 15, 2036 3.540 % (b) 6.463 % (e) Quarterly 2007 Junior Subordinated Deferrable Debentures June 21, 2007 $ 200,000 June 15, 2037 8.480 % (c) 5.180 % (e) Quarterly Flagstone 2007 Junior Subordinated Deferrable Debentures June 8, 2007 $ 100,000 July 30, 2037 3.000 % (b) 5.900 % (e) Quarterly Flagstone 2007 Junior Subordinated Deferrable Debentures September 20, 2007 $ 25,000 September 15, 2037 3.100 % (b) 5.983 % (e) Quarterly 2010 Senior Notes due 2040 January 26, 2010 $ 250,000 January 26, 2040 8.875 % (d) 8.875 % (d) Semi-annually in arrears (a) Fixed interest rate for 5 years , floating interest rate of three-month LIBOR plus 3.550% thereafter, reset quarterly. (b) Floating interest rate of three-month LIBOR plus amount stated, reset quarterly. (c) Fixed interest rate for 5 years , floating interest rate of three-month LIBOR plus 2.950% thereafter, reset quarterly. (d) Fixed interest rate. (e) Fixed interest rate as a result of interest rate swap contracts entered into by the Company.
Summary of outstanding credit and other facilities	The Company’s outstanding credit facilities as at June 30, 2018 and December 31, 2017 were as follows: June 30, 2018 Credit facility Commitment Outstanding (a) Drawn (b) Cash and investments pledged as collateral $85,000 syndicated unsecured letter of credit facility $ 85,000 $ — $ — $ — $300,000 syndicated secured letter of credit facility 300,000 98,267 — 123,632 $100,000 secured bi-lateral letter of credit facility 100,000 4,238 — 22,432 $25,000 IPC bi-lateral facility 25,000 7,702 — — $236,000 Flagstone bi-lateral facility 236,000 107,506 — 155,064 $65,000 unsecured revolving credit facility 65,000 — — — $100,000 unsecured revolving credit facility 100,000 — — — FHLB secured facility 548,898 206,000 206,000 238,499 Total credit facilities $ 1,459,898 $ 423,713 $ 206,000 $ 539,627 (a) Indicates utilization of commitment amount. (b) Represents drawn borrowings included in accounts payable and accrued expenses. December 31, 2017 Credit facility Commitment Outstanding (a) Drawn (b) Cash and investments pledged as collateral $85,000 syndicated unsecured letter of credit facility $ 85,000 $ — $ — $ — $300,000 syndicated secured letter of credit facility 300,000 92,979 — 118,188 $24,000 secured bi-lateral letter of credit facility 24,000 5,765 — 22,340 $25,000 IPC bi-lateral facility 25,000 7,754 — — $236,000 Flagstone bi-lateral facility 236,000 115,682 — 184,569 $65,000 unsecured revolving credit facility 65,000 — — — $100,000 unsecured revolving credit facility 100,000 — — — FHLB secured facility 484,096 206,000 206,000 251,767 Total credit facilities $ 1,319,096 $ 428,180 $ 206,000 $ 576,864 (a) Indicates utilization of commitment amount. (b) Represents drawn borrowings included in accounts payable and accrued expenses.
Components of finance expenses	Finance expenses consist of interest on the Junior Subordinated Deferrable Debentures and the 2010 Senior Notes, the amortization of debt offering costs, credit facility fees, bank and other charges and AlphaCat financing fees as follows: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 2006 Junior Subordinated Deferrable Debentures $ 2,212 $ 2,211 $ 4,398 $ 4,398 2007 Junior Subordinated Deferrable Debentures 1,831 1,831 3,641 3,641 Flagstone 2006 Junior Subordinated Deferrable Debentures 2,246 2,248 4,473 4,469 Flagstone 2007 Junior Subordinated Deferrable Debentures 1,722 1,751 3,435 3,474 2010 Senior Notes 5,598 5,598 11,195 11,195 Credit facilities 464 403 880 621 Bank and other charges 207 131 470 282 AlphaCat fees (a) 30 36 81 72 Total finance expenses $ 14,310 $ 14,209 $ 28,573 $ 28,152 (a) Includes finance expenses incurred by AlphaCat Managers Ltd. in relation to fund raising for the AlphaCat sidecars, the AlphaCat ILS funds and AlphaCat direct.

Accumulated other comprehensi37

Accumulated other comprehensive loss (Tables)	6 Months Ended
	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of changes in accumulated other comprehensive loss	The changes in accumulated other comprehensive income (loss), by component for the three and six months ended June 30, 2018 and 2017 are as follows: Three Months Ended June 30, 2018 Foreign currency translation adjustment Minimum pension liability Cash flow hedge Total Balance, net of tax, beginning of period $ (16,380 ) $ 2,681 $ 23,104 $ 9,405 Other comprehensive (loss) income, net of tax (2,737 ) 342 3,035 640 Amounts reclassified from accumulated other comprehensive income (loss) — — (186 ) (186 ) Balance, net of tax, end of period $ (19,117 ) $ 3,023 $ 25,953 $ 9,859 Three Months Ended June 30, 2017 Foreign currency translation adjustment Minimum pension liability Cash flow hedge Total Balance, net of tax, beginning of period $ (21,677 ) $ (82 ) $ (694 ) $ (22,453 ) Other comprehensive income (loss), net of tax 1,489 1,184 (144 ) 2,529 Balance, net of tax, end of period $ (20,188 ) $ 1,102 $ (838 ) $ (19,924 ) Six Months Ended June 30, 2018 Foreign currency translation adjustment Minimum pension liability Cash flow hedge Total Balance, net of tax, beginning of period $ (18,217 ) $ 2,719 $ (6,694 ) $ (22,192 ) Other comprehensive (loss) income, net of tax (900 ) 304 31,798 31,202 Amounts reclassified from accumulated other comprehensive income (loss) — — 849 849 Balance, net of tax, end of period $ (19,117 ) $ 3,023 $ 25,953 $ 9,859 Six Months Ended June 30, 2017 Foreign currency translation adjustment Minimum pension liability Cash flow hedge Total Balance, net of tax, beginning of period $ (22,274 ) $ (150 ) $ (792 ) $ (23,216 ) Other comprehensive income (loss), net of tax 2,086 1,252 (46 ) 3,292 Balance, net of tax, end of period $ (20,188 ) $ 1,102 $ (838 ) $ (19,924 )

Commitments and contingencies (

Commitments and contingencies (Tables)	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Unfunded investment commitments	As at June 30, 2018 and December 31, 2017 , the Company had total unfunded investment commitments related to the following: Unfunded investment commitments June 30, 2018 December 31, 2017 Fixed maturity investments (a) $ 26,477 $ 22,082 Other investments (b) 83,894 86,697 Investments in investment affiliates (c) 95,788 125,996 Total unfunded investment commitments $ 206,159 $ 234,775 (a) The Company has an outstanding commitment to participate in certain secured loan facilities through participation agreements with an established loan originator. (b) The Company’s total capital commitments related to other investments as at June 30, 2018 was $268,000 ( December 31, 2017 : $268,000 ). (c) Refer to Note 4 (c), “Investments in investment affiliates.”

Earnings per share (Tables)

Earnings per share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Computation of basic and diluted earnings per share	The following table sets forth the computation of basic (loss) earnings per common share and (loss) earnings per diluted common share available to Validus common shareholders for the three and six months ended June 30, 2018 and 2017 : Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Basic (loss) earnings per common share Net (loss) income (attributable) available to Validus common shareholders (52,898 ) 101,095 (56,976 ) 195,656 Weighted average number of common shares outstanding 79,650,474 79,270,561 79,488,081 79,202,116 Basic (loss) earnings per share (attributable) available to Validus common shareholders $ (0.66 ) $ 1.28 $ (0.72 ) $ 2.47 (Loss) earnings per diluted common share Net (loss) income (attributable) available to Validus common shareholders $ (52,898 ) $ 101,095 $ (56,976 ) $ 195,656 Weighted average number of common shares outstanding 79,650,474 79,270,561 79,488,081 79,202,116 Share equivalents: Stock options — 14,739 — 15,059 Unvested restricted shares — 1,587,151 — 1,644,823 Weighted average number of diluted common shares outstanding 79,650,474 80,872,451 79,488,081 80,861,998 (Loss) earnings per diluted common share (attributable) available to Validus common shareholders $ (0.66 ) $ 1.25 $ (0.72 ) $ 2.42

Segment information (Tables)

Segment information (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Summary of results of operating segments and Corporate and Investments	The following tables summarize the results of our reportable segments and “Corporate and Investments” function: Three Months Ended June 30, Six Months Ended June 30, Reinsurance Segment Information 2018 2017 2018 2017 Underwriting revenues Gross premiums written $ 360,588 $ 330,534 $ 1,126,161 $ 973,675 Reinsurance premiums ceded (16,368 ) (10,278 ) (206,562 ) (124,724 ) Net premiums written 344,220 320,256 919,599 848,951 Change in unearned premiums (106,697 ) (61,948 ) (457,324 ) (358,988 ) Net premiums earned 237,523 258,308 462,275 489,963 Other insurance related income — 1 2 3 Total underwriting revenues 237,523 258,309 462,277 489,966 Underwriting deductions Losses and loss expenses 117,338 114,341 220,811 195,222 Policy acquisition costs 52,157 49,966 100,497 93,501 General and administrative expenses 26,522 22,204 55,437 42,173 Share compensation expenses 3,972 2,725 6,635 5,348 Total underwriting deductions 199,989 189,236 383,380 336,244 Underwriting income $ 37,534 $ 69,073 $ 78,897 $ 153,722 Selected ratios: Ratio of net to gross premiums written 95.5 % 96.9 % 81.7 % 87.2 % Losses and loss expense ratio 49.4 % 44.3 % 47.8 % 39.8 % Policy acquisition cost ratio 22.0 % 19.3 % 21.7 % 19.1 % General and administrative expense ratio 12.8 % 9.7 % 13.4 % 9.7 % Expense ratio 34.8 % 29.0 % 35.1 % 28.8 % Combined ratio 84.2 % 73.3 % 82.9 % 68.6 % Three Months Ended June 30, Six Months Ended June 30, Insurance Segment Information 2018 2017 2018 2017 Underwriting revenues Gross premiums written $ 384,240 $ 360,057 $ 1,170,035 $ 742,847 Reinsurance premiums ceded (81,887 ) (49,315 ) (273,524 ) (128,315 ) Net premiums written 302,353 310,742 896,511 614,532 Change in unearned premiums 97,446 (5,875 ) (197,174 ) (30,571 ) Net premiums earned 399,799 304,867 699,337 583,961 Other insurance related income 35 728 2,205 1,724 Total underwriting revenues 399,834 305,595 701,542 585,685 Underwriting deductions Losses and loss expenses 342,854 180,741 526,243 367,351 Policy acquisition costs 57,650 60,137 117,707 121,329 General and administrative expenses 75,110 53,596 143,160 98,872 Share compensation expenses 4,242 3,702 7,231 7,075 Total underwriting deductions 479,856 298,176 794,341 594,627 Underwriting (loss) income $ (80,022 ) $ 7,419 $ (92,799 ) $ (8,942 ) Selected ratios: Ratio of net to gross premiums written 78.7 % 86.3 % 76.6 % 82.7 % Losses and loss expense ratio 85.8 % 59.3 % 75.2 % 62.9 % Policy acquisition cost ratio 14.4 % 19.7 % 16.8 % 20.8 % General and administrative expense ratio 19.8 % 18.8 % 21.5 % 18.1 % Expense ratio 34.2 % 38.5 % 38.3 % 38.9 % Combined ratio 120.0 % 97.8 % 113.5 % 101.8 % Three Months Ended June 30, Six Months Ended June 30, Asset Management Segment Information 2018 2017 2018 2017 Fee revenues Third party $ 5,685 $ 5,549 $ 11,894 $ 10,193 Related party 436 644 879 1,275 Total fee revenues 6,121 6,193 12,773 11,468 Expenses General and administrative expenses 4,835 3,549 9,382 7,393 Share compensation expenses 30 83 71 165 Finance expenses 18 44 96 75 Tax expense (benefit) 2 135 (5 ) 134 Foreign exchange losses — 1 1 — Total expenses 4,885 3,812 9,545 7,767 Income before investment income from funds and sidecars 1,236 2,381 3,228 3,701 Investment income (loss) from funds and sidecars (a) AlphaCat Sidecars 102 (21 ) 134 (133 ) AlphaCat ILS Funds - Lower Risk (b) 1,773 1,301 3,007 3,490 AlphaCat ILS Funds - Higher Risk (b) (796 ) 2,600 3,024 4,967 BetaCat ILS Funds 363 263 549 631 Validus' share of investment income from funds and sidecars 1,442 4,143 6,714 8,955 Asset Management segment income $ 2,678 $ 6,524 $ 9,942 $ 12,656 Gross premiums written AlphaCat Sidecars $ 9 $ — $ (134 ) $ 66 AlphaCat ILS Funds - Lower Risk (b) 62,577 53,632 172,527 106,540 AlphaCat ILS Funds - Higher Risk (b) 37,514 43,672 203,410 137,208 AlphaCat Direct (c) 2,278 8,378 13,200 26,794 Total $ 102,378 $ 105,682 $ 389,003 $ 270,608 (a) The investment income (loss) from funds and sidecars is based on equity accounting. (b) Lower risk AlphaCat ILS funds have a maximum permitted portfolio expected loss of less than 7%, whereas higher risk AlphaCat ILS funds have a maximum permitted portfolio expected loss of 7% or greater. The portfolio expected loss represents the average annual loss over the set of simulation scenarios divided by the total limit. (c) AlphaCat Direct includes direct investments from a third party investor in AlphaCat Re. Three Months Ended June 30, Six Months Ended June 30, Corporate and Investments 2018 2017 2018 2017 Managed investments Managed net investment income (a) $ 42,752 $ 38,063 $ 82,543 $ 74,255 Net realized (losses) gains on managed investments (a) (7,432 ) 2,269 (6,290 ) (623 ) Change in net unrealized (losses) gains on managed investments (a) (11,392 ) 15,942 (68,169 ) 30,291 Income from investment affiliates 2,178 9,466 15,246 14,654 Total managed investment return $ 26,106 $ 65,740 $ 23,330 $ 118,577 Corporate expenses General and administrative expenses $ 13,523 $ 16,219 $ 25,832 $ 34,180 Share compensation expenses 7,796 4,636 11,832 8,049 Finance expenses (a) 14,249 14,149 28,339 28,013 Dividends on preferred shares 5,828 2,203 11,656 4,406 Tax (benefit) (a) (7,153 ) (1,122 ) (13,979 ) (4,670 ) Total Corporate expenses $ 34,243 $ 36,085 $ 63,680 $ 69,978 Other items Foreign exchange losses (a) (1,652 ) (7,323 ) (1,655 ) (6,220 ) Other income 538 174 582 268 Transaction expenses (3,837 ) (4,427 ) (11,593 ) (4,427 ) Total other items $ (4,951 ) $ (11,576 ) $ (12,666 ) $ (10,379 ) Total Corporate and Investments $ (13,088 ) $ 18,079 $ (53,016 ) $ 38,220 (a) These items exclude the components which are included in the Asset Management segment income (loss) and amounts which are consolidated from VIEs. The following tables reconcile the results of our reportable segments and “Corporate & Investments” function to the Consolidated results of the Company for the periods indicated: Three Months Ended June 30, 2018 Reinsurance Segment Insurance Segment Asset Management Segment and Consolidated VIEs Corporate & Investments Eliminations Total Underwriting revenues Gross premiums written $ 360,588 $ 384,240 $ 102,378 $ — $ — $ 847,206 Reinsurance premiums ceded (16,368 ) (81,887 ) (9,312 ) — — (107,567 ) Net premiums written 344,220 302,353 93,066 — — 739,639 Change in unearned premiums (106,697 ) 97,446 6,219 — — (3,032 ) Net premiums earned 237,523 399,799 99,285 — — 736,607 Other insurance related income (loss) — 35 (12,261 ) — (4,428 ) (16,654 ) Total underwriting revenues 237,523 399,834 87,024 — (4,428 ) 719,953 Underwriting deductions Losses and loss expenses 117,338 342,854 16,418 — — 476,610 Policy acquisition costs 52,157 57,650 8,974 — — 118,781 General and administrative expenses 26,522 75,110 10,135 13,523 (4,428 ) 120,862 Share compensation expenses 3,972 4,242 30 7,796 — 16,040 Total underwriting deductions 199,989 479,856 35,557 21,319 (4,428 ) 732,293 Underwriting income (loss) $ 37,534 $ (80,022 ) $ 51,467 $ (21,319 ) $ — $ (12,340 ) Net investment return (a) — — 15,508 26,106 — 41,614 Other items (b) — — 1,063 (17,875 ) — (16,812 ) (Income) attributable to AlphaCat investors — — (29,849 ) — — (29,849 ) Net (income) attributable to noncontrolling interests — — (35,511 ) — — (35,511 ) Net income (loss) available (attributable) to Validus common shareholders $ 37,534 $ (80,022 ) $ 2,678 $ (13,088 ) $ — $ (52,898 ) (a) Net investment return includes net investment income, net realized and change in net unrealized gains (losses) on investments and income (loss) from investment affiliates. (b) Other items includes finance expenses, transaction expenses, dividends on preferred shares, tax benefit (expense), foreign exchange gains (losses), income (loss) from operating affiliate and other income (loss). Three Months Ended June 30, 2017 Reinsurance Segment Insurance Segment Asset Management Segment and Consolidated VIEs Corporate & Investments Eliminations Total Underwriting revenues Gross premiums written $ 330,534 $ 360,057 $ 105,682 $ — $ (3,371 ) $ 792,902 Reinsurance premiums ceded (10,278 ) (49,315 ) — — 3,371 (56,222 ) Net premiums written 320,256 310,742 105,682 — — 736,680 Change in unearned premiums (61,948 ) (5,875 ) (37,830 ) — — (105,653 ) Net premiums earned 258,308 304,867 67,852 — — 631,027 Other insurance related income 1 728 5,874 — (5,438 ) 1,165 Total underwriting revenues 258,309 305,595 73,726 — (5,438 ) 632,192 Underwriting deductions Losses and loss expenses 114,341 180,741 1,067 — — 296,149 Policy acquisition costs 49,966 60,137 7,165 — — 117,268 General and administrative expenses 22,204 53,596 9,768 16,219 (5,438 ) 96,349 Share compensation expenses 2,725 3,702 83 4,636 — 11,146 Total underwriting deductions 189,236 298,176 18,083 20,855 (5,438 ) 520,912 Underwriting income (loss) $ 69,073 $ 7,419 $ 55,643 $ (20,855 ) $ — $ 111,280 Net investment return (a) — — 6,562 65,740 — 72,302 Other items (b) — — (201 ) (26,806 ) — (27,007 ) (Income) attributable to AlphaCat investors — — (11,830 ) — — (11,830 ) Net (income) attributable to noncontrolling interests — — (43,650 ) — — (43,650 ) Net income available to Validus common shareholders $ 69,073 $ 7,419 $ 6,524 $ 18,079 $ — $ 101,095 (a) Net investment return includes net investment income, net realized and change in net unrealized gains (losses) on investments and income (loss) from investment affiliates. (b) Other items includes finance expenses, transaction expenses, dividends on preferred shares, tax benefit (expense), foreign exchange gains (losses), income (loss) from operating affiliate and other income (loss). Six Months Ended June 30, 2018 Reinsurance Segment Insurance Segment Asset Management Segment and Consolidated VIEs Corporate & Investments Eliminations Total Underwriting revenues Gross premiums written $ 1,126,161 $ 1,170,035 $ 389,003 $ — $ (5,537 ) $ 2,679,662 Reinsurance premiums ceded (206,562 ) (273,524 ) (9,312 ) — 5,537 (483,861 ) Net premiums written 919,599 896,511 379,691 — — 2,195,801 Change in unearned premiums (457,324 ) (197,174 ) (185,754 ) — — (840,252 ) Net premiums earned 462,275 699,337 193,937 — — 1,355,549 Other insurance related income 2 2,205 15,819 — (9,184 ) 8,842 Total underwriting revenues 462,277 701,542 209,756 — (9,184 ) 1,364,391 Underwriting deductions Losses and loss expenses 220,811 526,243 51,101 — — 798,155 Policy acquisition costs 100,497 117,707 17,033 — — 235,237 General and administrative expenses 55,437 143,160 20,343 25,832 (9,184 ) 235,588 Share compensation expenses 6,635 7,231 71 11,832 — 25,769 Total underwriting deductions 383,380 794,341 88,548 37,664 (9,184 ) 1,294,749 Underwriting income (loss) $ 78,897 $ (92,799 ) $ 121,208 $ (37,664 ) $ — $ 69,642 Net investment return (a) — — 28,243 23,330 — 51,573 Other items (b) — — 1,425 (38,682 ) — (37,257 ) (Income) attributable to AlphaCat investors — — (40,711 ) — — (40,711 ) Net (income) attributable to noncontrolling interests — — (100,223 ) — — (100,223 ) Net income (loss) available (attributable) to Validus common shareholders $ 78,897 $ (92,799 ) $ 9,942 $ (53,016 ) $ — $ (56,976 ) (a) Net investment return includes net investment income, net realized and change in net unrealized gains (losses) on investments and income (loss) from investment affiliates. (b) Other items includes finance expenses, transaction expenses, dividends on preferred shares, tax benefit (expense), foreign exchange gains (losses), income (loss) from operating affiliate and other income (loss). Six Months Ended June 30, 2017 Reinsurance Segment Insurance Segment Asset Management Segment and Consolidated VIEs Corporate & Investments Eliminations Total Underwriting revenues Gross premiums written $ 973,675 $ 742,847 $ 270,608 $ — $ (3,371 ) $ 1,983,759 Reinsurance premiums ceded (124,724 ) (128,315 ) (6,660 ) — 3,371 (256,328 ) Net premiums written 848,951 614,532 263,948 — — 1,727,431 Change in unearned premiums (358,988 ) (30,571 ) (131,469 ) — — (521,028 ) Net premiums earned 489,963 583,961 132,479 — — 1,206,403 Other insurance related income 3 1,724 11,035 — (10,361 ) 2,401 Total underwriting revenues 489,966 585,685 143,514 — (10,361 ) 1,208,804 Underwriting deductions Losses and loss expenses 195,222 367,351 3,161 — — 565,734 Policy acquisition costs 93,501 121,329 14,066 — — 228,896 General and administrative expenses 42,173 98,872 19,409 34,180 (10,361 ) 184,273 Share compensation expenses 5,348 7,075 165 8,049 — 20,637 Total underwriting deductions 336,244 594,627 36,801 42,229 (10,361 ) 999,540 Underwriting income (loss) $ 153,722 $ (8,942 ) $ 106,713 $ (42,229 ) $ — $ 209,264 Net investment return (a) — — 11,311 118,577 — 129,888 Other items (b) — — 187 (38,128 ) — (37,941 ) (Income) attributable to AlphaCat investors — — (19,333 ) — — (19,333 ) Net (income) attributable to noncontrolling interests — — (86,222 ) — — (86,222 ) Net income (loss) available (attributable) to Validus common shareholders $ 153,722 $ (8,942 ) $ 12,656 $ 38,220 $ — $ 195,656 (a) Net investment return includes net investment income, net realized and change in net unrealized gains (losses) on investments and income (loss) from investment affiliates. (b) Other items includes finance expenses, transaction expenses, dividends on preferred shares, tax benefit (expense), foreign exchange gains (losses), income (loss) from operating affiliate and other income (loss).
Gross premiums written allocated to the territory of coverage exposure	The Company’s exposures are generally diversified across geographic zones. The following tables set forth the gross premiums written allocated to the territory of coverage exposure for the periods indicated: Gross Premiums Written Three Months Ended June 30, 2018 Reinsurance Segment Insurance Segment Asset Management Segment Eliminations Total % United States $ 149,298 $ 188,253 $ 70,762 $ — $ 408,313 48.2 % Worldwide excluding United States (a) 12,962 41,430 (102 ) — 54,290 6.4 % Australia and New Zealand 33 (2,992 ) — — (2,959 ) (0.3 )% Europe 3,091 7,048 — — 10,139 1.2 % Latin America and Caribbean 10,581 25,429 — — 36,010 4.3 % Japan 43,467 2,213 1,833 — 47,513 5.6 % Canada 4,955 931 359 — 6,245 0.7 % Rest of the world (b) 5,971 24,559 — — 30,530 3.6 % Sub-total, non United States 81,060 98,618 2,090 — 181,768 21.5 % Worldwide including United States (a) 59,259 30,789 29,526 — 119,574 14.1 % Other locations non-specific (c) 70,971 66,580 — — 137,551 16.2 % Total $ 360,588 $ 384,240 $ 102,378 $ — $ 847,206 100.0 % Gross Premiums Written Three Months Ended June 30, 2017 Reinsurance Segment Insurance Segment Asset Management Segment Eliminations Total % United States $ 108,727 $ 157,048 $ 70,048 $ (3,371 ) $ 332,452 41.9 % Worldwide excluding United States (a) 5,378 37,295 870 — 43,543 5.5 % Australia and New Zealand 3,388 1,764 2,003 — 7,155 0.9 % Europe 1,168 5,711 (15 ) — 6,864 0.9 % Latin America and Caribbean 11,320 24,092 46 — 35,458 4.5 % Japan 40,832 1,848 2,662 — 45,342 5.7 % Canada 3,267 995 130 — 4,392 0.6 % Rest of the world (b) 5,062 22,940 — — 28,002 3.5 % Sub-total, non United States 70,415 94,645 5,696 — 170,756 21.6 % Worldwide including United States (a) 56,169 24,005 29,937 — 110,111 13.9 % Other locations non-specific (c) 95,223 84,359 1 — 179,583 22.6 % Total $ 330,534 $ 360,057 $ 105,682 $ (3,371 ) $ 792,902 100.0 % Gross Premiums Written Six Months Ended June 30, 2018 Reinsurance Segment Insurance Segment Asset Management Segment Eliminations Total % United States $ 349,472 $ 748,975 $ 101,785 $ (1,525 ) $ 1,198,707 44.7 % Worldwide excluding United States (a) 52,287 93,662 2,777 — 148,726 5.6 % Australia and New Zealand 1,169 5,185 — — 6,354 0.2 % Europe 41,073 12,608 338 — 54,019 2.0 % Latin America and Caribbean 17,120 43,874 — — 60,994 2.3 % Japan 45,567 3,129 2,264 — 50,960 1.9 % Canada 8,690 1,864 359 — 10,913 0.4 % Rest of the world (b) 24,269 51,779 — — 76,048 2.9 % Sub-total, non United States 190,175 212,101 5,738 — 408,014 15.3 % Worldwide including United States (a) 178,068 57,444 277,640 (4,012 ) 509,140 19.0 % Other locations non-specific (c) 408,446 151,515 3,840 — 563,801 21.0 % Total $ 1,126,161 $ 1,170,035 $ 389,003 $ (5,537 ) $ 2,679,662 100.0 % Gross Premiums Written Six Months Ended June 30, 2017 Reinsurance Segment Insurance Segment Asset Management Segment Eliminations Total % United States $ 332,655 $ 347,236 $ 98,251 $ (3,371 ) $ 774,771 39.1 % Worldwide excluding United States (a) 40,586 69,833 7,905 — 118,324 5.9 % Australia and New Zealand 4,177 4,938 2,003 — 11,118 0.6 % Europe 33,113 14,392 451 — 47,956 2.4 % Latin America and Caribbean 21,280 44,779 46 — 66,105 3.3 % Japan 42,783 2,853 3,855 — 49,491 2.5 % Canada 5,625 1,444 130 — 7,199 0.4 % Rest of the world (b) 20,165 43,332 — — 63,497 3.2 % Sub-total, non United States 167,729 181,571 14,390 — 363,690 18.3 % Worldwide including United States (a) 151,970 51,192 153,246 — 356,408 18.0 % Other locations non-specific (c) 321,321 162,848 4,721 — 488,890 24.6 % Total $ 973,675 $ 742,847 $ 270,608 $ (3,371 ) $ 1,983,759 100.0 % (a) Represents risks in two or more geographic zones. (b) Represents risks in one geographic zone. (c) The other locations non-specific category refers to business for which an analysis of exposure by geographic zone is not applicable since these exposures can span multiple geographic areas and, in some instances, are not fixed locations.

Business combinations (Narrativ

Business combinations (Narrative) (Details) $ / shares in Units, $ in Thousands	May 01, 2017USD ($)StatesAgent	Jul. 18, 2018$ / shares	Jun. 30, 2018$ / shares
Business Acquisition [Line Items]
Common shares, par value			$ 0.175
Crop Risk Services
Business Acquisition [Line Items]
Total purchase price | $	$ 185,576
Number of agents | Agent	1,170
Number of states | States	36
Subsequent Event [Member]
Business Acquisition [Line Items]
Common shares, par value		$ 0.01
Subsequent Event [Member] | American International Group, Inc.
Business Acquisition [Line Items]
Share price		$ 68

Investments (Amortized cost or

Investments (Amortized cost or cost and fair value of investments) (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		$ 5,651,953		$ 5,876,261
Short-term investments, at amortized cost or cost		3,728,930		3,381,714
Other investments, at amortized cost or cost		341,883		330,416
Investments in investment affiliates, at cost		72,135		61,944
Total investments		9,794,901		9,650,335
Fixed maturities, at fair value		5,559,953		5,858,348
Short-term investments, at fair value		3,728,894		3,381,757
Other investments, at fair value		366,184		355,218
Investments in investment affiliates, at fair value		127,247		100,137
Total investments		9,782,278		9,695,460
Managed investments
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		5,472,977		5,644,929
Short-term investments, at amortized cost or cost		218,071		229,968
Other investments, at amortized cost or cost		341,883		330,416
Total investments		6,105,066		6,267,257
Fixed maturities, at fair value		5,381,011		5,628,654
Short-term investments, at fair value		218,035		230,011
Other investments, at fair value		366,184		355,218
Total investments		6,092,477		6,314,020
Managed investments | U.S. government and government agency
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		613,130		733,510
Fixed maturities, at fair value		604,392		727,397
Managed investments | Non-U.S. government and government agency
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		285,514		310,845
Fixed maturities, at fair value		282,263		312,239
Managed investments | U.S. states, municipalities and political subdivisions
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		191,065		201,347
Fixed maturities, at fair value		189,437		201,303
Managed investments | Agency residential mortgage-backed securities
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		956,254		984,387
Fixed maturities, at fair value		929,859		978,049
Managed investments | Non-agency residential mortgage-backed securities
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		48,061		40,264
Fixed maturities, at fair value		47,600		40,373
Managed investments | U.S. corporate
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		1,459,190		1,531,498
Fixed maturities, at fair value		1,436,885		1,533,395
Managed investments | Non-U.S. corporate
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		410,287		420,522
Fixed maturities, at fair value		403,385		422,249
Managed investments | Bank loans
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		480,593		450,320
Fixed maturities, at fair value		471,212		442,951
Managed investments | Asset-backed securities
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		719,803		657,234
Fixed maturities, at fair value		714,434		658,303
Managed investments | Commercial mortgage-backed securities
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		309,080		315,002
Fixed maturities, at fair value		301,544		312,395
Managed investments | Hedge funds
Amortized cost (or cost) and estimated fair value of investments
Other investments, at amortized cost or cost		6,954		6,954
Other investments, at fair value		15,888		15,774
Managed investments | Private equity investments
Amortized cost (or cost) and estimated fair value of investments
Other investments, at amortized cost or cost		64,921		63,684
Other investments, at fair value		79,185		78,407
Managed investments | Fixed income investment funds
Amortized cost (or cost) and estimated fair value of investments
Other investments, at amortized cost or cost		208,400		203,167
Other investments, at fair value		209,503		204,426
Managed investments | Overseas deposits
Amortized cost (or cost) and estimated fair value of investments
Other investments, at amortized cost or cost		61,608		56,611
Other investments, at fair value		61,608		56,611
Non-managed investments
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		178,976		231,332
Short-term investments, at amortized cost or cost		3,510,859		3,151,746
Total investments		3,689,835		3,383,078
Fixed maturities, at fair value		178,942		229,694
Short-term investments, at fair value		3,510,859		3,151,746
Total investments		3,689,801		3,381,440
Non-managed investments | Catastrophe bonds
Amortized cost (or cost) and estimated fair value of investments
Fixed maturities, at amortized cost or cost		178,976		231,332
Fixed maturities, at fair value		178,942		229,694
Investment affiliate
Amortized cost (or cost) and estimated fair value of investments
Investments in investment affiliates, at cost	[1]	72,135		61,944
Investments in investment affiliates, at fair value		$ 127,247	$ 113,471	$ 100,137	$ 103,377	$ 94,697	$ 100,431
[1]	The Company’s investments in investment affiliates have been treated as equity method investments with the corresponding gains and losses recorded in income as “Income from investment affiliates.”

Investments (Fixed maturities b

Investments (Fixed maturities by investment rating) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fixed Maturities
Fair value	$ 5,559,953	$ 5,858,348
Percentage of total	100.00%	100.00%
Managed investments
Fixed Maturities
Fair value	$ 5,381,011	$ 5,628,654
Percentage of total	96.80%	96.10%
Managed investments | Total investment grade fixed maturities
Fixed Maturities
Fair value	$ 4,878,788	$ 5,123,658
Percentage of total	87.80%	87.50%
Managed investments | Total investment grade fixed maturities | AAA
Fixed Maturities
Fair value	$ 2,560,857	$ 2,715,074
Percentage of total	46.20%	46.40%
Managed investments | Total investment grade fixed maturities | AA
Fixed Maturities
Fair value	$ 417,814	$ 442,397
Percentage of total	7.50%	7.60%
Managed investments | Total investment grade fixed maturities | A rating
Fixed Maturities
Fair value	$ 1,102,419	$ 1,137,795
Percentage of total	19.80%	19.40%
Managed investments | Total investment grade fixed maturities | BBB
Fixed Maturities
Fair value	$ 797,698	$ 828,392
Percentage of total	14.30%	14.10%
Managed investments | Total non-investment grade fixed maturities
Fixed Maturities
Fair value	$ 502,223	$ 504,996
Percentage of total	9.00%	8.60%
Managed investments | Total non-investment grade fixed maturities | BB
Fixed Maturities
Fair value	$ 157,241	$ 168,967
Percentage of total	2.80%	2.90%
Managed investments | Total non-investment grade fixed maturities | B
Fixed Maturities
Fair value	$ 227,954	$ 237,131
Percentage of total	4.10%	4.00%
Managed investments | Total non-investment grade fixed maturities | CCC
Fixed Maturities
Fair value	$ 20,219	$ 18,217
Percentage of total	0.40%	0.30%
Managed investments | Total non-investment grade fixed maturities | CC
Fixed Maturities
Fair value	$ 564	$ 0
Percentage of total	0.00%	0.00%
Managed investments | Total non-investment grade fixed maturities | NR
Fixed Maturities
Fair value	$ 96,245	$ 80,681
Percentage of total	1.70%	1.40%
Non-managed investments
Fixed Maturities
Fair value	$ 178,942	$ 229,694
Percentage of total	3.20%	3.90%
Non-managed investments | Total investment grade fixed maturities
Fixed Maturities
Fair value	$ 250	$ 0
Percentage of total	0.00%	0.00%
Non-managed investments | Total investment grade fixed maturities | AAA
Fixed Maturities
Fair value	$ 250	$ 0
Percentage of total	0.00%	0.00%
Non-managed investments | Total non-investment grade fixed maturities
Fixed Maturities
Fair value	$ 178,692	$ 229,694
Percentage of total	3.20%	3.90%
Non-managed investments | Total non-investment grade fixed maturities | BB
Fixed Maturities
Fair value	$ 6,632	$ 22,110
Percentage of total	0.20%	0.30%
Non-managed investments | Total non-investment grade fixed maturities | B
Fixed Maturities
Fair value	$ 2,626	$ 3,265
Percentage of total	0.00%	0.10%
Non-managed investments | Total non-investment grade fixed maturities | NR
Fixed Maturities
Fair value	$ 169,434	$ 204,319
Percentage of total	3.00%	3.50%

Investments (Maturity profile o

Investments (Maturity profile of fixed maturity investments) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Maturity profile
Amortized cost	$ 5,651,953	$ 5,876,261
Fair value	5,559,953	5,858,348
Managed investments
Maturity profile
Amortized cost	5,472,977	5,644,929
Fair value	5,381,011	5,628,654
Managed investments | Asset backed and mortgaged backed securities
Maturity profile
Amortized cost	2,033,198	1,996,887
Fair value	1,993,437	1,989,120
Managed investments | Fixed maturities trading securities allocated to contractual maturity
Maturity profile
Amortized cost	3,439,779	3,648,042
Fair value	3,387,574	3,639,534
Managed investments | Fixed maturities trading securities allocated to contractual maturity | Due in one year or less
Maturity profile
Amortized cost	361,061	343,360
Fair value	359,094	343,541
Managed investments | Fixed maturities trading securities allocated to contractual maturity | Due after one year through five years
Maturity profile
Amortized cost	2,333,731	2,527,018
Fair value	2,295,728	2,513,620
Managed investments | Fixed maturities trading securities allocated to contractual maturity | Due after five years through ten years
Maturity profile
Amortized cost	556,784	577,347
Fair value	547,685	577,109
Managed investments | Fixed maturities trading securities allocated to contractual maturity | Due after ten years
Maturity profile
Amortized cost	188,203	200,317
Fair value	185,067	205,264
Non-managed investments
Maturity profile
Amortized cost	178,976	231,332
Fair value	178,942	229,694
Non-managed investments | Due in one year or less
Maturity profile
Amortized cost	47,918	88,797
Fair value	46,922	88,367
Non-managed investments | Due after one year through five years
Maturity profile
Amortized cost	130,433	140,035
Fair value	131,395	138,844
Non-managed investments | Due after five years through ten years
Maturity profile
Amortized cost	625	2,500
Fair value	$ 625	$ 2,483

Investments (Other investments)

Investments (Other investments) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Jun. 30, 2018
Investment [Line Items]
Other investments, at fair value		$ 355,218	$ 366,184
Managed investments
Investment [Line Items]
Other investments, at fair value		355,218	366,184
Managed investments | Hedge funds
Investment [Line Items]
Other investments, at fair value		15,774	15,888
Managed investments | Private equity investments
Investment [Line Items]
Other investments, at fair value		78,407	79,185
Managed investments | Fixed income investment funds
Investment [Line Items]
Other investments, at fair value		204,426	209,503
Managed investments | Overseas deposits
Investment [Line Items]
Other investments, at fair value		56,611	61,608
Managed investments | Subject to redemption restriction
Investment [Line Items]
Other investments, at fair value		351,324	366,184
Managed investments | Subject to redemption restriction | Hedge funds
Investment [Line Items]
Other investments, at fair value		15,774	15,888
Managed investments | Subject to redemption restriction | Private equity investments
Investment [Line Items]
Other investments, at fair value		78,407	79,185
Managed investments | Subject to redemption restriction | Fixed income investment funds
Investment [Line Items]
Other investments, at fair value		200,532	209,503
Managed investments | Subject to redemption restriction | Overseas deposits
Investment [Line Items]
Other investments, at fair value		56,611	61,608
Managed investments | Not subject to redemption restriction
Investment [Line Items]
Other investments, at fair value		3,894	0
Managed investments | Not subject to redemption restriction | Hedge funds
Investment [Line Items]
Other investments, at fair value		0	0
Managed investments | Not subject to redemption restriction | Private equity investments
Investment [Line Items]
Other investments, at fair value		0	0
Managed investments | Not subject to redemption restriction | Fixed income investment funds
Investment [Line Items]
Other investments, at fair value		$ 3,894	0
Redemption frequency	[1]	Daily
Managed investments | Not subject to redemption restriction | Fixed income investment funds | Minimum
Investment [Line Items]
Redemption notice period		1 day
Managed investments | Not subject to redemption restriction | Fixed income investment funds | Maximum
Investment [Line Items]
Redemption notice period		2 days
Managed investments | Not subject to redemption restriction | Overseas deposits
Investment [Line Items]
Other investments, at fair value		$ 0	$ 0
[1]	The redemption frequency and notice periods only apply to investments without redemption restrictions.

Investments (Investment affilia

Investments (Investment affiliate rollforward) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule of Equity Method Investments [Line Items]
Investments in affiliates, beginning of period			$ 100,137
Income from investment affiliates	$ 2,178	$ 9,466	15,246	$ 14,654
Investments in affiliates, end of period	127,247		127,247
Investment affiliate
Schedule of Equity Method Investments [Line Items]
Investments in affiliates, beginning of period	113,471	94,697	100,137	100,431
Income from investment affiliates	11,598	(786)	11,864	(11,708)
Income from investment affiliates	2,178	9,466	15,246	14,654
Investments in affiliates, end of period	$ 127,247	$ 103,377	$ 127,247	$ 103,377

Investments (Investment affil47

Investments (Investment affiliate details) (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Remaining commitment		$ 206,159		$ 234,775
Investments in investment affiliates, at cost		72,135		61,944
Investments in affiliates		127,247		100,137
Investment affiliate
Schedule of Equity Method Investments [Line Items]
Remaining commitment		95,788		125,996
Investments in investment affiliates, at cost	[1]	72,135		61,944
Investments in affiliates		127,247	$ 113,471	100,137	$ 103,377	$ 94,697	$ 100,431
Investment affiliate | Aquiline Financial Services Fund II LP
Schedule of Equity Method Investments [Line Items]
Investments in investment affiliates, at cost		$ 28,529		$ 33,349
Voting ownership %		0.00%		0.00%
Equity ownership %		8.10%		8.10%
Investments in affiliates		$ 49,248		$ 51,914
Investment affiliate | Aquiline Financial Services Fund III LP
Schedule of Equity Method Investments [Line Items]
Investments in investment affiliates, at cost		$ 25,501		$ 24,737
Voting ownership %		0.00%		0.00%
Equity ownership %		9.00%		9.00%
Investments in affiliates		$ 59,900		$ 44,733
Investment affiliate | Aquiline Tech
Schedule of Equity Method Investments [Line Items]
Investments in investment affiliates, at cost		$ 4,406		$ 3,858
Voting ownership %		0.00%		0.00%
Equity ownership %		10.60%		10.60%
Investments in affiliates		$ 4,400		$ 3,490
Investment affiliate | Aquiline Armour
Schedule of Equity Method Investments [Line Items]
Investments in investment affiliates, at cost		$ 13,699
Voting ownership %		0.00%
Equity ownership %		15.20%
Investments in affiliates		$ 13,699
[1]	The Company’s investments in investment affiliates have been treated as equity method investments with the corresponding gains and losses recorded in income as “Income from investment affiliates.”

Investments (Components of net

Investments (Components of net investment income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net investment income
Net investment income	$ 57,560	$ 44,241	$ 109,632	$ 84,455
Managed investments
Net investment income
Total gross investment income	45,818	39,506	88,952	78,670
Investment expenses	(3,066)	(1,443)	(6,409)	(4,415)
Net investment income	42,752	38,063	82,543	74,255
Managed investments | Fixed maturities and short term investments
Net investment income
Total gross investment income	39,224	31,212	76,993	62,883
Managed investments | Other investments
Net investment income
Total gross investment income	4,846	7,571	9,069	14,441
Managed investments | Restricted cash, cash and cash equivalents
Net investment income
Total gross investment income	1,744	716	2,883	1,326
Managed investments | Securities lending income
Net investment income
Total gross investment income	4	7	7	20
Non-managed investments
Net investment income
Net investment income	14,808	6,178	27,089	10,200
Non-managed investments | Fixed maturities and short term investments
Net investment income
Total gross investment income	5,842	4,500	9,990	7,560
Non-managed investments | Restricted cash, cash and cash equivalents
Net investment income
Total gross investment income	$ 8,966	$ 1,678	$ 17,099	$ 2,640

Investments (Realized and unrea

Investments (Realized and unrealized gains) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fixed Maturities Short Term And Other Investments And Cash Equivalents [Abstract]
Net realized gains (losses) on investments	$ (7,394)	$ 2,274	$ (5,194)	$ 1,110
Change in net unrealized (losses) gains on investments	(10,730)	16,321	(68,111)	29,669
Total net realized and change in net unrealized gains (losses) on investments	(18,124)	18,595	(73,305)	30,779
Managed investments
Fixed Maturities Short Term And Other Investments And Cash Equivalents [Abstract]
Gross realized gains	3,048	5,175	9,878	7,865
Gross realized (losses)	(10,480)	(2,906)	(16,168)	(8,488)
Net realized gains (losses) on investments	(7,432)	2,269	(6,290)	(623)
Change in net unrealized (losses) gains on investments	(11,392)	15,942	(68,169)	30,291
Total net realized and change in net unrealized gains (losses) on investments	(18,824)	18,211	(74,459)	29,668
Non-managed investments
Fixed Maturities Short Term And Other Investments And Cash Equivalents [Abstract]
Gross realized gains	175	5	1,410	1,733
Gross realized (losses)	(137)	0	(314)	0
Net realized gains (losses) on investments	38	5	1,096	1,733
Change in net unrealized (losses) gains on investments	662	379	58	(622)
Total net realized and change in net unrealized gains (losses) on investments	$ 700	$ 384	$ 1,154	$ 1,111

Investments (Narrative) (Detail

Investments (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other investments, at fair value	$ 366,184	$ 355,218
Cash, cash equivalents, restricted cash and investments pledged as collateral	6,310,851	5,853,744
Investments held in trust	6,282,368	5,789,081
Investments and cash pledged as collateral	539,627	576,864
Managed investments
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other investments, at fair value	366,184	355,218
Managed investments | Subject to redemption restriction
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other investments, at fair value	$ 366,184	351,324
Managed investments | Minimum | Subject to redemption restriction
Schedule of Trading Securities and Other Trading Assets [Line Items]
Redemption restriction period	5 years
Managed investments | Maximum | Subject to redemption restriction
Schedule of Trading Securities and Other Trading Assets [Line Items]
Redemption restriction period	10 years
Rated or consist of externally rated securities | Managed investments
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other investments, at fair value	$ 196,379	186,734
Not externally rated | Managed investments
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other investments, at fair value	$ 169,805	$ 168,484

Fair value measurements (Fair v

Fair value measurements (Fair value hierarchy) (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		$ 5,559,953	$ 5,858,348
Short-term investments, at fair value		3,728,894	3,381,757
Other investments, at fair value		366,184	355,218
Investments in affiliates		127,247	100,137
Total investments		9,782,278	9,695,460
Managed investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		5,381,011	5,628,654
Short-term investments, at fair value		218,035	230,011
Other investments, at fair value		366,184	355,218
Total investments		6,092,477	6,314,020
Managed investments | U.S. government and government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		604,392	727,397
Managed investments | Non-US government and government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		282,263	312,239
Managed investments | U.S. states, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		189,437	201,303
Managed investments | Agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		929,859	978,049
Managed investments | Non-Agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		47,600	40,373
Managed investments | U.S. corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		1,436,885	1,533,395
Managed investments | Non-U.S. corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		403,385	422,249
Managed investments | Bank loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		471,212	442,951
Managed investments | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		714,434	658,303
Managed investments | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		301,544	312,395
Managed investments | Hedge funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		15,888	15,774
Managed investments | Private equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		79,185	78,407
Managed investments | Fixed income investment funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		209,503	204,426
Managed investments | Overseas deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		61,608	56,611
Non-managed investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		178,942	229,694
Short-term investments, at fair value		3,510,859	3,151,746
Total investments		3,689,801	3,381,440
Non-managed investments | Catastrophe bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		178,942	229,694
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments		9,782,278	9,695,460
Recurring | Fair value based on NAV practical expedient
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	[1]	337,801	324,463
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments		3,698,090	3,349,800
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments		5,221,770	5,512,317
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments		397,370	408,743
Recurring | Managed investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		5,381,011	5,628,654
Short-term investments, at fair value		218,035	230,011
Other investments, at fair value		366,184	355,218
Total investments		6,092,477	6,314,020
Recurring | Managed investments | U.S. government and government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		604,392	727,397
Recurring | Managed investments | Non-US government and government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		282,263	312,239
Recurring | Managed investments | U.S. states, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		189,437	201,303
Recurring | Managed investments | Agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		929,859	978,049
Recurring | Managed investments | Non-Agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		47,600	40,373
Recurring | Managed investments | U.S. corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		1,436,885	1,533,395
Recurring | Managed investments | Non-U.S. corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		403,385	422,249
Recurring | Managed investments | Bank loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		471,212	442,951
Recurring | Managed investments | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		714,434	658,303
Recurring | Managed investments | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		301,544	312,395
Recurring | Managed investments | Hedge funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		15,888	15,774
Recurring | Managed investments | Private equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		79,185	78,407
Recurring | Managed investments | Fixed income investment funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		209,503	204,426
Recurring | Managed investments | Overseas deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		61,608	56,611
Recurring | Managed investments | Fair value based on NAV practical expedient
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	[1]	0	0
Short-term investments, at fair value	[1]	0	0
Other investments, at fair value	[1]	337,801	324,463
Total investments	[1]	337,801	324,463
Recurring | Managed investments | Fair value based on NAV practical expedient | U.S. government and government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	[1]	0	0
Recurring | Managed investments | Fair value based on NAV practical expedient | Non-US government and government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	[1]	0	0
Recurring | Managed investments | Fair value based on NAV practical expedient | U.S. states, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	[1]	0	0
Recurring | Managed investments | Fair value based on NAV practical expedient | Agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	[1]	0	0
Recurring | Managed investments | Fair value based on NAV practical expedient | Non-Agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	[1]	0	0
Recurring | Managed investments | Fair value based on NAV practical expedient | U.S. corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	[1]	0	0
Recurring | Managed investments | Fair value based on NAV practical expedient | Non-U.S. corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	[1]	0	0
Recurring | Managed investments | Fair value based on NAV practical expedient | Bank loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	[1]	0	0
Recurring | Managed investments | Fair value based on NAV practical expedient | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	[1]	0	0
Recurring | Managed investments | Fair value based on NAV practical expedient | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	[1]	0	0
Recurring | Managed investments | Fair value based on NAV practical expedient | Hedge funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value	[1]	15,888	15,774
Recurring | Managed investments | Fair value based on NAV practical expedient | Private equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value	[1]	79,185	78,407
Recurring | Managed investments | Fair value based on NAV practical expedient | Fixed income investment funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value	[1]	181,120	173,671
Recurring | Managed investments | Fair value based on NAV practical expedient | Overseas deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value	[1]	61,608	56,611
Recurring | Managed investments | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Short-term investments, at fair value		187,231	198,054
Other investments, at fair value		0	0
Total investments		187,231	198,054
Recurring | Managed investments | Level 1 | U.S. government and government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 1 | Non-US government and government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 1 | U.S. states, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 1 | Agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 1 | Non-Agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 1 | U.S. corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 1 | Non-U.S. corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 1 | Bank loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 1 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 1 | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 1 | Hedge funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		0	0
Recurring | Managed investments | Level 1 | Private equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		0	0
Recurring | Managed investments | Level 1 | Fixed income investment funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		0	0
Recurring | Managed investments | Level 1 | Overseas deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		0	0
Recurring | Managed investments | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		5,054,010	5,314,776
Short-term investments, at fair value		30,804	31,957
Other investments, at fair value		9,576	13,351
Total investments		5,094,390	5,360,084
Recurring | Managed investments | Level 2 | U.S. government and government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		604,392	727,397
Recurring | Managed investments | Level 2 | Non-US government and government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		282,263	312,239
Recurring | Managed investments | Level 2 | U.S. states, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		189,437	201,303
Recurring | Managed investments | Level 2 | Agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		929,859	978,049
Recurring | Managed investments | Level 2 | Non-Agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		47,600	40,373
Recurring | Managed investments | Level 2 | U.S. corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		1,436,885	1,533,395
Recurring | Managed investments | Level 2 | Non-U.S. corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		403,385	422,249
Recurring | Managed investments | Level 2 | Bank loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		245,476	232,886
Recurring | Managed investments | Level 2 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		613,169	554,490
Recurring | Managed investments | Level 2 | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		301,544	312,395
Recurring | Managed investments | Level 2 | Hedge funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		0	0
Recurring | Managed investments | Level 2 | Private equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		0	0
Recurring | Managed investments | Level 2 | Fixed income investment funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		9,576	13,351
Recurring | Managed investments | Level 2 | Overseas deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		0	0
Recurring | Managed investments | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		327,001	313,878
Short-term investments, at fair value		0	0
Other investments, at fair value		18,807	17,404
Total investments		345,808	331,282
Recurring | Managed investments | Level 3 | U.S. government and government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 3 | Non-US government and government agency
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 3 | U.S. states, municipalities and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 3 | Agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 3 | Non-Agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 3 | U.S. corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 3 | Non-U.S. corporate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 3 | Bank loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		225,736	210,065
Recurring | Managed investments | Level 3 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		101,265	103,813
Recurring | Managed investments | Level 3 | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Managed investments | Level 3 | Hedge funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		0	0
Recurring | Managed investments | Level 3 | Private equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		0	0
Recurring | Managed investments | Level 3 | Fixed income investment funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		18,807	17,404
Recurring | Managed investments | Level 3 | Overseas deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments, at fair value		0	0
Recurring | Non-managed investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, at fair value		3,510,859	3,151,746
Total investments		3,689,801	3,381,440
Recurring | Non-managed investments | Catastrophe bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		178,942	229,694
Recurring | Non-managed investments | Fair value based on NAV practical expedient
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, at fair value	[1]	0	0
Total investments	[1]	0	0
Recurring | Non-managed investments | Fair value based on NAV practical expedient | Catastrophe bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value	[1]	0	0
Recurring | Non-managed investments | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, at fair value		3,510,859	3,151,746
Total investments		3,510,859	3,151,746
Recurring | Non-managed investments | Level 1 | Catastrophe bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		0	0
Recurring | Non-managed investments | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, at fair value		0	0
Total investments		127,380	152,233
Recurring | Non-managed investments | Level 2 | Catastrophe bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		127,380	152,233
Recurring | Non-managed investments | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments, at fair value		0	0
Total investments		51,562	77,461
Recurring | Non-managed investments | Level 3 | Catastrophe bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities, at fair value		$ 51,562	$ 77,461
[1]	In accordance with ASC Topic 820 “Fair Value Measurements,” investments measured at fair value using the net asset value (“NAV”) per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy.

Fair value measurements (Level

Fair value measurements (Level 3 rollforward) (Details) - Recurring - Level 3 - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reconciliation of beginning and ending balances for all investments measured at fair value on recurring basis
Level 3 investments - beginning of period	$ 412,949	$ 345,812	$ 408,743	$ 330,970
Purchases	15,296	36,242	65,435	120,509
Sales	(70)	(53)	(140)	(53)
Settlements	(29,699)	(38,701)	(75,025)	(110,199)
Realized gains		216	1,235	3,350
Change in net unrealized (losses) gains	(1,106)	1,002	(2,878)	(59)
Level 3 investments - end of period	397,370	344,518	397,370	344,518
Transfers Into (Out of) Level 3	0	0	0	0
Bank loan portfolio
Reconciliation of beginning and ending balances for all investments measured at fair value on recurring basis
Level 3 investments - beginning of period	227,503	236,694	210,065	246,496
Purchases	14,422	16,757	45,207	39,933
Sales	0	0	0	0
Settlements	(14,698)	(28,893)	(28,540)	(62,003)
Realized gains		0	0	0
Change in net unrealized (losses) gains	(1,491)	(386)	(996)	(254)
Level 3 investments - end of period	225,736	224,172	225,736	224,172
Catastrophe bonds
Reconciliation of beginning and ending balances for all investments measured at fair value on recurring basis
Level 3 investments - beginning of period	65,697	72,676	77,461	48,375
Purchases	0	5,000	18,825	66,091
Sales	0	0	0	0
Settlements	(15,001)	(10,216)	(46,485)	(48,996)
Realized gains		216	1,235	3,350
Change in net unrealized (losses) gains	866	349	526	(795)
Level 3 investments - end of period	51,562	68,025	51,562	68,025
Fixed income investment funds
Reconciliation of beginning and ending balances for all investments measured at fair value on recurring basis
Level 3 investments - beginning of period	17,933	12,560	17,404	12,168
Purchases	874	3,432	1,403	3,432
Sales	0	0	0	0
Settlements	0	408	0	800
Realized gains		0	0	0
Change in net unrealized (losses) gains	0	0	0	0
Level 3 investments - end of period	18,807	16,400	18,807	16,400
Asset-backed securities
Reconciliation of beginning and ending balances for all investments measured at fair value on recurring basis
Level 3 investments - beginning of period	101,816	23,882	103,813	23,931
Purchases	0	11,053	0	11,053
Sales	(70)	(53)	(140)	(53)
Settlements	0	0	0	0
Realized gains		0	0	0
Change in net unrealized (losses) gains	(481)	1,039	(2,408)	990
Level 3 investments - end of period	$ 101,265	$ 35,921	$ 101,265	$ 35,921

Fair value measurements (Narrat

Fair value measurements (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Trading Securities	$ 9,782,278	$ 9,695,460
Managed investments
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Trading Securities	6,092,477	6,314,020
Recurring
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Trading Securities	$ 9,782,278	9,695,460
Recurring | Hedge funds
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Investment Time Lag Reporting	3 months
Recurring | Minimum | Private equity investments
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Investment Time Lag Reporting	3 months
Recurring | Minimum | Fixed income investment funds
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Investment Time Lag Reporting	1 month
Recurring | Maximum | Private equity investments
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Investment Time Lag Reporting	6 months
Recurring | Maximum | Fixed income investment funds
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Investment Time Lag Reporting	3 months
Recurring | Managed investments
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Trading Securities	$ 6,092,477	6,314,020
Recurring | Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Trading Securities	397,370	408,743
Recurring | Level 3 | Managed investments
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Trading Securities	$ 345,808	$ 331,282
Ratio of Level 3 investments to total investments (percent)	5.70%	5.20%

Variable interest entities (Not

Variable interest entities (Notes payable to AlphaCat investors) (Details) - Variable interest entities, primary beneficiary - AlphaCat ILS funds - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Variable Interest Entity [Line Items]
Notes payable to AlphaCat investors, beginning of period	$ 1,268,194	$ 446,576	$ 1,108,364	$ 278,202
Notes payable to AlphaCat investors recognized on deconsolidation of AlphaCat ILS fund		423,269		423,269
Issuance of notes payable to AlphaCat investors	305,319	336,747	991,831	714,077
Redemption of notes payable to AlphaCat investors	(362,565)	(140,150)	(893,111)	(349,106)
Foreign exchange losses	(4,277)	(283)	(413)	(283)
Notes payable to AlphaCat investors, end of period	1,206,671	1,066,159	1,206,671	1,066,159
Variable Funding Notes
Variable Interest Entity [Line Items]
Notes payable to AlphaCat investors, beginning of period	916,022	343,256	936,164	278,202
Notes payable to AlphaCat investors recognized on deconsolidation of AlphaCat ILS fund		423,269		423,269
Issuance of notes payable to AlphaCat investors	305,039	267,867	811,579	541,877
Redemption of notes payable to AlphaCat investors	(362,565)	(140,150)	(893,111)	(349,106)
Foreign exchange losses	(4,277)	(283)	(413)	(283)
Notes payable to AlphaCat investors, end of period	854,219	893,959	854,219	893,959
Structured Notes
Variable Interest Entity [Line Items]
Notes payable to AlphaCat investors, beginning of period	352,172	103,320	172,200	0
Notes payable to AlphaCat investors recognized on deconsolidation of AlphaCat ILS fund		0		0
Issuance of notes payable to AlphaCat investors	280	68,880	180,252	172,200
Redemption of notes payable to AlphaCat investors	0	0	0	0
Foreign exchange losses	0	0	0	0
Notes payable to AlphaCat investors, end of period	$ 352,452	$ 172,200	$ 352,452	$ 172,200

Variable interest entities (Ass

Variable interest entities (Assets and liabilities of consolidated VIEs) (Details) - Variable interest entities, primary beneficiary - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2016
AlphaCat sidecars
Variable Interest Entity [Line Items]
Total assets	$ 15,647	$ 25,975
Total liabilities	3,102	3,267
AlphaCat ILS funds - Lower Risk
Variable Interest Entity [Line Items]
Total assets	1,205,476	1,107,503
Total liabilities	86,339	259,630
AlphaCat ILS funds - Higher Risk
Variable Interest Entity [Line Items]
Total assets	1,162,492	1,310,071
Total liabilities	383,231	912,341
AlphaCat Re and AlphaCat Master Fund
Variable Interest Entity [Line Items]
Total assets	3,830,442	3,398,082
Total liabilities	3,830,272	3,397,912
BetaCat ILS funds
Variable Interest Entity [Line Items]
Total assets	89,161	77,221
Total liabilities	$ 210	$ 261

Variable interest entities (Nar

Variable interest entities (Narrative) (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018USD ($)funds	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)funds	Jun. 30, 2017USD ($)	Dec. 31, 2017
Variable Interest Entity [Line Items]
Risk profile percentage			7.00%
Variable funding notes, typical minimum duration			12 months
(Income) attributable to AlphaCat investors	$ 29,849	$ 11,830	$ 40,711	$ 19,333
Accounts payable and accrued expenses
Variable Interest Entity [Line Items]
(Income) attributable to AlphaCat investors			66,259	18,054
AlphaCat ILS funds | Variable interest entities, primary beneficiary
Variable Interest Entity [Line Items]
Variable Interest Entity Redemption Of Notes Payable To AlphaCat Investors	$ 362,565	$ 140,150	$ 893,111	$ 349,106
ILS fund issuing structured notes
Variable Interest Entity [Line Items]
Structured notes interest rate percentage			6.50%		7.00%
BetaCat ILS funds
Variable Interest Entity [Line Items]
Number of BetaCat ILS funds | funds	3		3
BetaCat ILS funds | Variable interest entities, primary beneficiary
Variable Interest Entity [Line Items]
Number of BetaCat ILS funds | funds	2		2

Noncontrolling interest (Detail

Noncontrolling interest (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Noncontrolling Interest [Line Items]
Balance, beginning of period	$ 1,757,467	$ 1,988,227	$ 1,020,812	$ 1,693,978
Issuance of shares	121,850	209,821	788,450	468,500
Adjustment to noncontrolling interests as a result of deconsolidation	0	(459,021)	0	(459,021)
Income attributable to noncontrolling interests	35,511	43,650	100,223	86,222
Redemption of shares / Distributions	(153,338)	(115,359)	(147,995)	(122,361)
Balance, end of period	1,761,490	1,667,318	1,761,490	1,667,318
Redeemable noncontrolling interest
Noncontrolling Interest [Line Items]
Balance, beginning of period	1,423,110	1,657,630	1,004,094	1,528,001
Issuance of shares	81,250	106,501	466,550	210,200
Adjustment to noncontrolling interests as a result of deconsolidation	0	(459,021)	0	(459,021)
Income attributable to noncontrolling interests	19,255	28,555	47,628	54,485
Redemption of shares	(133,382)	(82,005)	(128,039)	(82,005)
Balance, end of period	1,390,233	1,251,660	1,390,233	1,251,660
Balances payable to noncontrolling interests	80,315		80,315		$ 180,104
Noncontrolling interest
Noncontrolling Interest [Line Items]
Balance, beginning of period	334,357	330,597	16,718	165,977
Issuance of shares	40,600	103,320	321,900	258,300
Income attributable to noncontrolling interests	16,256	15,095	52,595	31,737
Distributions	(19,956)	(33,354)	(19,956)	(40,356)
Balance, end of period	$ 371,257	$ 415,658	$ 371,257	$ 415,658

Derivative instruments (Amount

Derivative instruments (Amount and balance sheet location) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Not designated as hedging instruments | Foreign currency forward contracts
Summary of derivatives
Net Notional Exposure	$ 190,952	$ 283,765
Not designated as hedging instruments | Foreign currency forward contracts | Other assets
Summary of derivatives
Fair value, derivative assets	3,880	1,147
Not designated as hedging instruments | Foreign currency forward contracts | Accounts payable and accrued expenses
Summary of derivatives
Fair value, derivative liabilities	3,310	906
Not designated as hedging instruments | Interest rate swap contracts
Summary of derivatives
Net Notional Exposure	200,000	200,000
Not designated as hedging instruments | Interest rate swap contracts | Other assets
Summary of derivatives
Fair value, derivative assets	10,306	1,589
Not designated as hedging instruments | Interest rate swap contracts | Accounts payable and accrued expenses
Summary of derivatives
Fair value, derivative liabilities	0	0
Not designated as hedging instruments | Weather derivative contracts
Summary of derivatives
Net Notional Exposure	4,825	4,825
Not designated as hedging instruments | Weather derivative contracts | Other assets
Summary of derivatives
Fair value, derivative assets	8,380	853
Not designated as hedging instruments | Weather derivative contracts | Accounts payable and accrued expenses
Summary of derivatives
Fair value, derivative liabilities	0	0
Designated as hedging instruments | Foreign currency forward contracts
Summary of derivatives
Net Notional Exposure	64,405	96,293
Designated as hedging instruments | Foreign currency forward contracts | Other assets
Summary of derivatives
Fair value, derivative assets	0	1,891
Designated as hedging instruments | Foreign currency forward contracts | Accounts payable and accrued expenses
Summary of derivatives
Fair value, derivative liabilities	546	0
Designated as hedging instruments | Interest rate swap contracts
Summary of derivatives
Net Notional Exposure	552,263	552,263
Designated as hedging instruments | Interest rate swap contracts | Other assets
Summary of derivatives
Fair value, derivative assets	28,982	9,806
Designated as hedging instruments | Interest rate swap contracts | Accounts payable and accrued expenses
Summary of derivatives
Fair value, derivative liabilities	$ 2,627	$ 18,840

Derivative instruments (Amoun59

Derivative instruments (Amount included in statement of operations) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Not designated as hedging instruments | Foreign currency forward contracts | Foreign exchange gains (losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in earnings	$ 4,843	$ (6,525)	$ (358)	$ (6,072)
Not designated as hedging instruments | Foreign currency forward contracts | Other insurance related income and other income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in earnings	0	(874)	0	(979)
Not designated as hedging instruments | Interest rate swap contracts | Net realized gains on investments
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in earnings	2,123	(319)	8,067	(319)
Not designated as hedging instruments | Weather derivative contracts | Other insurance related income and other income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative gains (losses) recognized in earnings	(17,910)	0	8,863	0
Designated as hedging instruments | Cash flow hedge | Foreign currency forward contracts | Other comprehensive income
Derivative instruments designated as a cash flow hedge
Amount of effective portion recognized in other comprehensive income	(4,165)	0	(1,245)	0
Designated as hedging instruments | Cash flow hedge | Foreign currency forward contracts | General and administrative expense
Derivative instruments designated as a cash flow hedge
Amount of effective portion subsequently reclassified to earnings	(884)	0	(1,192)	0
Designated as hedging instruments | Cash flow hedge | Interest rate swap contracts | Other comprehensive income
Derivative instruments designated as a cash flow hedge
Amount of effective portion recognized in other comprehensive income	7,200	(144)	33,043	(46)
Designated as hedging instruments | Cash flow hedge | Interest rate swap contracts | Finance expenses
Derivative instruments designated as a cash flow hedge
Amount of effective portion subsequently reclassified to earnings	$ 698	$ 0	$ 2,041	$ 0

Reserve for losses and loss e60

Reserve for losses and loss expenses (Components of reserves for losses and loss expenses) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Insurance Loss Reserves [Abstract]
Case reserves	$ 1,836,130		$ 1,753,844
IBNR	2,863,469		3,077,546
Reserve for losses and loss expenses	$ 4,699,599	$ 4,632,629	$ 4,831,390	$ 3,305,191	$ 3,052,745	$ 2,995,195

Reserve for losses and loss e61

Reserve for losses and loss expenses (Reserve rollforward) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reserve for paid losses and unpaid loss expenses
Reserve for losses and loss expenses, beginning of period	$ 4,632,629	$ 3,052,745	$ 4,831,390	$ 2,995,195
Loss reserves recoverable, beginning of period	(979,944)	(451,856)	(1,233,997)	(430,421)
Net reserves for losses and loss expenses, beginning of period	3,652,685	2,600,889	3,597,393	2,564,774
Net reserves acquired	0	23,753	0	23,753
Increase (decrease) in net losses and loss expenses incurred in respect of losses occurring in:
Current year	489,181	339,439	818,296	670,255
Prior years	(12,571)	(43,290)	(20,141)	(104,521)
Total incurred losses and loss expenses	476,610	296,149	798,155	565,734
Foreign exchange losses (gains)	(30,348)	20,216	(14,721)	32,533
Less net losses and loss expenses paid in respect of losses occurring in:
Current year	(61,340)	(42,758)	(81,075)	(50,456)
Prior years	(308,958)	(193,265)	(571,103)	(431,354)
Total net paid losses	(370,298)	(236,023)	(652,178)	(481,810)
Net reserve for losses and loss expenses, end of period	3,728,649	2,704,984	3,728,649	2,704,984
Loss reserves recoverable, end of period	970,950	600,207	970,950	600,207
Reserve for losses and loss expenses, end of period	4,699,599	3,305,191	4,699,599	3,305,191
Components of incurred losses and loss expenses
Gross losses and loss expenses	535,438	410,421	784,219	746,863
Reinsurance recoverable	(58,828)	(114,272)	13,936	(181,129)
Net incurred losses and loss expenses	$ 476,610	$ 296,149	$ 798,155	$ 565,734

Reserve for losses and loss e62

Reserve for losses and loss expenses (Prior year development) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	$ (12,571)	$ (43,290)	$ (20,141)	$ (104,521)
Operating Segments
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	(12,571)	(43,290)	(20,141)	(104,521)
Operating Segments | Reinsurance segment
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	(14,810)	(15,708)	(32,648)	(46,832)
Operating Segments | Insurance segment
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	4,964	(23,730)	(10,584)	(50,419)
Operating Segments | Asset management segment
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	(2,725)	(3,852)	23,091	(7,270)
Operating Segments | Property Line of Business [Member]
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	(6,508)	(9,141)	17,938	(26,264)
Operating Segments | Property Line of Business [Member] | Reinsurance segment
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	(9,634)	(697)	(14,456)	(4,759)
Operating Segments | Property Line of Business [Member] | Insurance segment
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	4,792	(5,347)	8,860	(14,013)
Operating Segments | Property Line of Business [Member] | Asset management segment
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	(1,666)	(3,097)	23,534	(7,492)
Operating Segments | Specialty Short Tail Line of Business [Member]
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	(6,346)	(24,448)	(31,382)	(61,982)
Operating Segments | Specialty Short Tail Line of Business [Member] | Reinsurance segment
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	(10,273)	(14,344)	(23,724)	(41,092)
Operating Segments | Specialty Short Tail Line of Business [Member] | Insurance segment
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	4,986	(9,349)	(7,215)	(21,112)
Operating Segments | Specialty Short Tail Line of Business [Member] | Asset management segment
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	(1,059)	(755)	(443)	222
Operating Segments | Specialty Other Line of Business [Member]
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	283	(9,701)	(6,697)	(16,275)
Operating Segments | Specialty Other Line of Business [Member] | Reinsurance segment
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	5,097	(667)	5,532	(981)
Operating Segments | Specialty Other Line of Business [Member] | Insurance segment
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	(4,814)	(9,034)	(12,229)	(15,294)
Operating Segments | Specialty Other Line of Business [Member] | Asset management segment
Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
Net (favorable) adverse development on prior years	$ 0	$ 0	$ 0	$ 0

Reinsurance (Components of rein

Reinsurance (Components of reinsurance) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Reinsurance Disclosures [Abstract]
Outstanding losses	$ 287,141		$ 275,450
IBNR	683,809		958,547
Total loss reserves recoverable	970,950	$ 979,944	1,233,997	$ 600,207	$ 451,856	$ 430,421
Paid losses recoverable	71,876		46,873
Total reinsurance balances recoverable	$ 1,042,826		$ 1,280,870

Reinsurance (Ceded credit risk)

Reinsurance (Ceded credit risk) (Details) - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
		Jun. 30, 2018	Dec. 31, 2017
Ceded Credit Risk [Line Items]
Provision for uncollectible reinsurance relating to losses recoverable		$ 8,003	$ 8,848
Reinsurance Recoverable
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 1,042,826	$ 1,280,870
Percentage of total		100.00%	100.00%
Reinsurance Recoverable | A- or better
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 1,033,890	$ 1,270,503
Percentage of total		99.10%	99.20%
Reinsurance Recoverable | Top 10 reinsurers
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 857,819	$ 1,055,445
Percentage of total		82.20%	82.50%
Reinsurance Recoverable | Top 10 reinsurers | Fully collateralized reinsurers | NR
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 400,415	$ 459,339
Percentage of total		38.40%	35.90%
Reinsurance Recoverable | Top 10 reinsurers | Everest Re | A plus
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 120,146	$ 128,206
Percentage of total		11.50%	10.00%
Reinsurance Recoverable | Top 10 reinsurers | Lloyds Syndicates | A plus
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 75,841	$ 74,277
Percentage of total		7.30%	5.80%
Reinsurance Recoverable | Top 10 reinsurers | Swiss Re | AA- rating
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 49,857	$ 65,218
Percentage of total		4.80%	5.10%
Reinsurance Recoverable | Top 10 reinsurers | Munich Re | AA- rating
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 46,444	$ 94,180
Percentage of total		4.50%	7.40%
Reinsurance Recoverable | Top 10 reinsurers | Hannover Re | AA- rating
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 46,353	$ 53,523
Percentage of total		4.40%	4.20%
Reinsurance Recoverable | Top 10 reinsurers | Transatlantic Re | A plus
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 43,050	$ 33,729
Percentage of total		4.10%	2.60%
Reinsurance Recoverable | Top 10 reinsurers | Qatar Insurance Company | A rating
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 31,107	$ 50,160
Percentage of total		3.00%	3.90%
Reinsurance Recoverable | Top 10 reinsurers | Exor | BBB plus
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 23,283
Percentage of total		2.20%
Reinsurance Recoverable | Top 10 reinsurers | Markel | A rating
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 21,323	$ 28,068
Percentage of total		2.00%	2.20%
Reinsurance Recoverable | Top 10 reinsurers | Federal Crop Insurance Corporation
Ceded Credit Risk [Line Items]
Reinsurance recoverable	[1]		$ 68,745
Percentage of total	[1]		5.40%
Reinsurance Recoverable | Other reinsurers' balances greater than $1 million
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 176,212	$ 218,226
Percentage of total		17.00%	17.00%
Reinsurance Recoverable | Other reinsurers' balances less than $1 million
Ceded Credit Risk [Line Items]
Reinsurance recoverable		$ 8,795	$ 7,199
Percentage of total		0.80%	0.50%
[1]	The Company participates in a crop reinsurance program sponsored by the U.S. federal government. The Company remains obligated for amounts ceded in the event that its reinsurers or retrocessionaires do not meet their obligations, except for amounts ceded to the U.S. federal government in the Insurance segment agriculture line of business.

Share capital (Preferred stock)

Share capital (Preferred stock) (Details) $ / shares in Units, $ in Thousands	Jun. 12, 2017USD ($)$ / sharesshares	Jun. 13, 2016USD ($)$ / sharesshares	Jun. 30, 2018USD ($)shares	Jun. 30, 2017USD ($)	Dec. 31, 2017shares
Preferred shares - Shareholders' Equity
Preferred shares, shares issued | shares			16,000		16,000
Preferred shares, shares outstanding | shares			16,000		16,000
Net proceeds on issuance of preferred shares | $			$ 0	$ 241,686
Series A preferred shares
Preferred shares - Shareholders' Equity
Preferred shares, dividend rate, percentage		5.875%
Preferred shares, shares issued | shares		6,000	6,000		6,000
Preferred shares, shares outstanding | shares			6,000		6,000
Preferred stock, par or stated value per share		$ 0.175
Preferred stock, liquidation preference, per share		25,000
Preferred stock, issue price per share		$ 25,000
Net proceeds on issuance of preferred shares | $		$ 144,852
Series A depositary share equivalent
Preferred shares - Shareholders' Equity
Preferred shares equivalent depositary shares number | shares		6,000,000
Proportionate interest of preferred shares, per depositary share		0.001
Preferred stock, liquidation preference, per share		$ 25
Preferred stock, issue price per share		$ 25
Series B preferred shares
Preferred shares - Shareholders' Equity
Preferred shares, dividend rate, percentage	5.80%
Preferred shares, shares issued | shares	10,000		10,000		10,000
Preferred shares, shares outstanding | shares			10,000		10,000
Preferred stock, par or stated value per share	$ 0.175
Preferred stock, liquidation preference, per share	25,000
Preferred stock, issue price per share	$ 25,000
Net proceeds on issuance of preferred shares | $	$ 241,686
Series B depositary share equivalent
Preferred shares - Shareholders' Equity
Preferred shares equivalent depositary shares number | shares	10,000,000
Proportionate interest of preferred shares, per depositary share	0.001
Preferred stock, liquidation preference, per share	$ 25
Preferred stock, issue price per share	$ 25

Share capital (Common stock) (D

Share capital (Common stock) (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jul. 18, 2018
Share Capital (Narrative)
Common shares, par value	$ 0.175
Common stock voting rights	one vote per share
Maximum voting percent	9.09%
Share repurchases
Share repurchase program, cumulative shares repurchased	81,035,969
Shares repurchased, cumulative	$ 2,730,975
Remaining share repurchase authorization amount	$ 293,426
Summary of common shares issued and outstanding
Common shares issued, beginning balance	161,994,491	161,279,976
Common shares issued, ending balance	163,186,889	161,934,355
Treasury shares, end of period	(82,674,941)	(82,415,774)
Common shares outstanding, ending balance	80,511,948	79,518,581
Restricted share awards
Summary of common shares issued and outstanding
Vested, net of shares withheld	1,015,069	597,021
Restricted share units
Summary of common shares issued and outstanding
Vested, net of shares withheld	63,702	14,948
Performance shares
Summary of common shares issued and outstanding
Vested, net of shares withheld	113,627	42,410
Subsequent Event [Member]
Share Capital (Narrative)
Number of common shares authorized			80,000,000
Common shares, par value			$ 0.01
Number of preferred shares authorized			16,000
Preferred stock, par or stated value per share			$ 0.175

Share capital (Dividends) (Deta

Share capital (Dividends) (Details) - $ / shares	3 Months Ended				6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017
Class of Stock [Line Items]
Cash dividends declared per share - common shares	$ 0.38	$ 0.38	$ 0.38	$ 0.38	$ 0.76	$ 0.76
Series A depositary share equivalent
Class of Stock [Line Items]
Cash dividends declared per share - preferred shares	0.3671875	0.3671875	$ 0.3671875	$ 0.3671875
Series B depositary share equivalent
Class of Stock [Line Items]
Cash dividends declared per share - preferred shares	$ 0.3625	$ 0.3625000

Stock plans (Options activity)

Stock plans (Options activity) (Details)	Jun. 30, 2017$ / sharesshares
Options activities:
Options outstanding, beginning balance (in shares) | shares	26,136
Options outstanding, ending balance (in shares) | shares	26,136
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, beginning balance (in dollars per share)	$ 6.78
Weighted average grant date fair value, ending balance (in dollars per share)	6.78
Weighted Average Grant Date Exercise Price
Weighted average grant date exercise price, beginning balance (in dollars per share)	23.48
Weighted average grant date exercise price, ending balance (in dollars per share)	$ 23.48

Stock plans (Other awards activ

Stock plans (Other awards activity) (Details) - $ / shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Restricted share awards
Activities
Beginning balance (in shares)	2,080,397	2,469,982
Granted (in shares)	1,552	481,619
Vested (in shares)	(1,322,774)	(803,764)
Forfeited (in shares)	(15,985)	(39,617)
Ending balance (in shares)	743,190	2,108,220
Weighted average grant date fair value
Weighted average grant date fair value, beginning balance (in dollars per share)	$ 43.66	$ 40.89
Weighted average grant date fair value, granted (in dollars per share)	67.64	53.42
Weighted average grant date fair value, vested (in dollars per share)	40.13	41.31
Weighted average grant date fair value, forfeited (in dollars per share)	47.32	41.98
Weighted average grant date fair value, ending balance (in dollars per share)	$ 49.92	$ 43.58
Restricted share units
Activities
Beginning balance (in shares)	109,394	112,808
Granted (in shares)	0	12,236
Vested (in shares)	(81,139)	(18,241)
Issued in lieu of cash dividends (in shares)	2,105	1,468
Forfeited (in shares)	(17)	0
Ending balance (in shares)	30,343	108,271
Weighted average grant date fair value
Weighted average grant date fair value, beginning balance (in dollars per share)	$ 42.20	$ 40.95
Weighted average grant date fair value, granted (in dollars per share)	0	53.40
Weighted average grant date fair value, vested (in dollars per share)	39.27	41.66
Weighted average grant date fair value, issued in lieu of cash dividends (in dollars per share)	42.25	40.98
Weighted average grant date fair value, forfeited (in dollars per share)	44.63	0
Weighted average grant date fair value, ending balance (in dollars per share)	$ 50.04	$ 42.24
Performance shares
Activities
Beginning balance (in shares)	314,068	285,820
Granted (in shares)	0	107,209
Vested (in shares)	(142,749)	(52,639)
Conversion adjustment (in shares)	235,564	(26,322)
Ending balance (in shares)	406,883	314,068
Weighted average grant date fair value
Weighted average grant date fair value, beginning balance (in dollars per share)	$ 49.37	$ 44.53
Weighted average grant date fair value, granted (in dollars per share)	0	53.40
Weighted average grant date fair value, vested (in dollars per share)	45.03	37.33
Weighted average grant date fair value, conversion adjustment (in dollars per share)	49.37	36.82
Weighted average grant date fair value, ending balance (in dollars per share)	$ 50.89	$ 49.37

Stock plans (Components of shar

Stock plans (Components of share compensation expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Total share compensation expenses
Share compensation expenses	$ 16,040	$ 11,146	$ 25,769	$ 20,637
Restricted share awards
Total share compensation expenses
Share compensation expenses	7,190	9,745	15,303	18,789
Restricted share units
Total share compensation expenses
Share compensation expenses	284	327	616	642
Performance shares
Total share compensation expenses
Share compensation expenses	$ 8,566	$ 1,074	$ 9,850	$ 1,206

Stock plans (Narrative) (Detail

Stock plans (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Stock plans (other details)
Number of shares reserved for issuance under the LTIP and STIP	2,753,292		2,753,292
Remaining number of shares reserved for issuance	479,086		479,086
Share compensation expenses	$ 16,040	$ 11,146	$ 25,769	$ 20,637
Options
Stock plans (other details)
Life of options			10 years
Restricted share awards
Stock plans (other details)
Share compensation expenses	7,190	9,745	$ 15,303	18,789
Unrecognized share compensation expenses	33,551		$ 33,551		$ 48,907
Weighted average period of recognizing share based compensation expenses			2 years 1 month 9 days		2 years 3 months 18 days
Restricted share units
Stock plans (other details)
Share compensation expenses	284	327	$ 616	642
Unrecognized share compensation expenses	1,319		$ 1,319		$ 1,909
Weighted average period of recognizing share based compensation expenses			2 years 3 months 10 days		2 years 4 months 17 days
Performance shares
Stock plans (other details)
Share compensation expenses	8,566	$ 1,074	$ 9,850	$ 1,206
Unrecognized share compensation expenses	$ 9,501		$ 9,501		$ 7,813
Weighted average period of recognizing share based compensation expenses			1 year 7 months 2 days		1 year 11 months 4 days
Performance share awards performance period			3 years

Debt and financing arrangemen72

Debt and financing arrangements (Summary of outstanding debentures and senior notes payable) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Instruments [Line Items]
Debentures payable	$ 538,751	$ 539,158
Face amount	250,000	250,000
Less: Unamortized debt issuance costs	(4,336)	(4,436)
Total senior notes payable	245,664	245,564
Debentures payable	784,415	784,722
2006 Junior Subordinated
Debt Instruments [Line Items]
Debentures payable	150,000	150,000
2007 Junior Subordinated
Debt Instruments [Line Items]
Debentures payable	139,800	139,800
Face amount	200,000
Flagstone 2006 Junior Subordinated
Debt Instruments [Line Items]
Debentures payable	135,201	135,608
Flagstone 2007 Due July 30 2037
Debt Instruments [Line Items]
Debentures payable	113,750	$ 113,750
Face amount	$ 100,000

Debt and financing arrangemen73

Debt and financing arrangements (Summary of key terms of senior notes and debentures) (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2018	Dec. 31, 2017
Debt Instruments [Line Items]
Commitment		$ 250,000	$ 250,000
Debentures payable		$ 538,751	539,158
2006 Junior Subordinated
Debt Instruments [Line Items]
Issuance date		Jun. 15, 2006
Maturity date		Jun. 15, 2036
Interest payments due		Quarterly
Interest rate term		5 years
Debentures payable		$ 150,000	150,000
2006 Junior Subordinated | Three month LIBOR
Debt Instruments [Line Items]
Spread on variable rate (in percent)		3.55%
Flagstone 2006 Junior Subordinated
Debt Instruments [Line Items]
Issuance date		Aug. 23, 2006
Maturity date		Sep. 15, 2036
Interest payments due		Quarterly
Debentures payable		$ 135,201	135,608
2007 Junior Subordinated
Debt Instruments [Line Items]
Issuance date		Jun. 21, 2007
Commitment		$ 200,000
Maturity date		Jun. 15, 2037
Interest payments due		Quarterly
Interest rate term		5 years
Debentures payable		$ 139,800	139,800
2007 Junior Subordinated | Three month LIBOR
Debt Instruments [Line Items]
Spread on variable rate (in percent)		2.95%
Flagstone 2007 Due July 30 2037
Debt Instruments [Line Items]
Issuance date		Jun. 8, 2007
Commitment		$ 100,000
Maturity date		Jul. 30, 2037
Interest payments due		Quarterly
Debentures payable		$ 113,750	$ 113,750
Flagstone 2007 Due September 15 2037
Debt Instruments [Line Items]
Issuance date		Sep. 20, 2007
Commitment		$ 25,000
Maturity date		Sep. 15, 2037
Interest payments due		Quarterly
2010 Senior Notes Due 2040
Debt Instruments [Line Items]
Issuance date		Jan. 26, 2010
Commitment		$ 250,000
Maturity date		Jan. 26, 2040
Fixed interest rate (in percent)	[1]	8.875%
Interest payments due		Semi-annually in arrears
At Issuance | 2006 Junior Subordinated
Debt Instruments [Line Items]
Fixed interest rate (in percent)	[2]	9.069%
At Issuance | Flagstone 2006 Junior Subordinated | Three month LIBOR
Debt Instruments [Line Items]
Spread on variable rate (in percent)	[3]	3.54%
At Issuance | 2007 Junior Subordinated
Debt Instruments [Line Items]
Fixed interest rate (in percent)	[4]	8.48%
At Issuance | Flagstone 2007 Due July 30 2037 | Three month LIBOR
Debt Instruments [Line Items]
Spread on variable rate (in percent)	[3]	3.00%
At Issuance | Flagstone 2007 Due September 15 2037 | Three month LIBOR
Debt Instruments [Line Items]
Spread on variable rate (in percent)	[3]	3.10%
At Issuance | 2010 Senior Notes Due 2040
Debt Instruments [Line Items]
Fixed interest rate (in percent)	[1]	8.875%
Outstanding | 2006 Junior Subordinated
Debt Instruments [Line Items]
Effective percentage	[5]	5.831%
Outstanding | Flagstone 2006 Junior Subordinated
Debt Instruments [Line Items]
Effective percentage	[5]	6.463%
Outstanding | 2007 Junior Subordinated
Debt Instruments [Line Items]
Effective percentage	[5]	5.18%
Outstanding | Flagstone 2007 Due July 30 2037
Debt Instruments [Line Items]
Effective percentage	[5]	5.90%
Outstanding | Flagstone 2007 Due September 15 2037
Debt Instruments [Line Items]
Effective percentage	[5]	5.983%
Outstanding | 2010 Senior Notes Due 2040
Debt Instruments [Line Items]
Fixed interest rate (in percent)	[1]	8.875%
[1]	Fixed interest rate.
[2]	Fixed interest rate for 5 years, floating interest rate of three-month LIBOR plus 3.550% thereafter, reset quarterly.
[3]	Floating interest rate of three-month LIBOR plus amount stated, reset quarterly
[4]	Fixed interest rate for 5 years, floating interest rate of three-month LIBOR plus 2.950% thereafter, reset quarterly.
[5]	Fixed interest rate as a result of interest rate swap contracts entered into by the Company.

Debt and financing arrangemen74

Debt and financing arrangements (Credit facilities outstanding) (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Line of Credit Facility [Line Items]
Commitment		$ 1,459,898	$ 1,319,096
Outstanding		423,713	428,180
Drawn		206,000	206,000
Cash and investments pledged as collateral		539,627	576,864
$85,000 syndicated unsecured letter of credit facility
Line of Credit Facility [Line Items]
Commitment		85,000	85,000
Outstanding	[1]	0	0
$300,000 syndicated secured letter of credit facility
Line of Credit Facility [Line Items]
Commitment		300,000	300,000
Outstanding	[1]	98,267	92,979
Cash and investments pledged as collateral		123,632	118,188
$100,000 secured bi-lateral letter of credit facility
Line of Credit Facility [Line Items]
Commitment		100,000	24,000
Outstanding	[1]	4,238	5,765
Cash and investments pledged as collateral		22,432	22,340
$25,000 IPC bi-lateral facility
Line of Credit Facility [Line Items]
Commitment		25,000	25,000
Outstanding	[1]	7,702	7,754
$236,000 Flagstone bi-lateral facility
Line of Credit Facility [Line Items]
Commitment		236,000	236,000
Outstanding	[1]	107,506	115,682
Cash and investments pledged as collateral		155,064	184,569
$65,000 unsecured revolving credit facility
Line of Credit Facility [Line Items]
Commitment		65,000	65,000
Outstanding	[1]	0	0
Drawn	[2]	0	0
$100,000 unsecured revolving credit facility
Line of Credit Facility [Line Items]
Commitment		100,000	100,000
Outstanding	[1]	0	0
Drawn	[2]	0	0
FHLB secured facility
Line of Credit Facility [Line Items]
Commitment		548,898	484,096
Outstanding	[1]	206,000	206,000
Drawn	[2]	206,000	206,000
Cash and investments pledged as collateral		$ 238,499	$ 251,767
[1]	Indicates utilization of commitment amount.
[2]	Represents drawn borrowings included in accounts payable and accrued expenses.

Debt and financing arrangemen75

Debt and financing arrangements (Components of finance expenses) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Debt Instruments [Line Items]
Finance expenses	$ 14,310		$ 14,209		$ 28,573	$ 28,152
2006 Junior Subordinated
Debt Instruments [Line Items]
Finance expenses	2,212		2,211		4,398	4,398
2007 Junior Subordinated
Debt Instruments [Line Items]
Finance expenses	1,831		1,831		3,641	3,641
Flagstone 2006 Junior Subordinated
Debt Instruments [Line Items]
Finance expenses	2,246		2,248		4,473	4,469
Flagstone 2007 Junior Subordinated
Debt Instruments [Line Items]
Finance expenses	1,722		1,751		3,435	3,474
2010 Senior Notes Due 2040
Debt Instruments [Line Items]
Finance expenses	5,598		5,598		11,195	11,195
Credit facilities
Debt Instruments [Line Items]
Finance expenses	464		403		880	621
Bank and other charges
Debt Instruments [Line Items]
Finance expenses	207		131		470	282
AlphaCat fees
Debt Instruments [Line Items]
Finance expenses	$ 30	[1]	$ 36	[1]	$ 81	$ 72
[1]	Includes finance expenses incurred by AlphaCat Managers Ltd. in relation to fund raising for the AlphaCat sidecars, the AlphaCat ILS funds and AlphaCat direct.

Accumulated other comprehensi76

Accumulated other comprehensive loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance - Beginning of period			$ 3,895,072
Amounts reclassified from accumulated other comprehensive income (loss)				$ 0
Balance - End of period	$ 3,809,136	$ 4,211,431	3,809,136	4,211,431
Accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance - Beginning of period	9,405	(22,453)	(22,192)	(23,216)
Other comprehensive income (loss), net of tax	640	2,529	31,202	3,292
Amounts reclassified from accumulated other comprehensive income (loss)	(186)		849
Balance - End of period	9,859	(19,924)	9,859	(19,924)
Foreign currency translation adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance - Beginning of period	(16,380)	(21,677)	(18,217)	(22,274)
Other comprehensive income (loss), net of tax	(2,737)	1,489	(900)	2,086
Amounts reclassified from accumulated other comprehensive income (loss)			0
Balance - End of period	(19,117)	(20,188)	(19,117)	(20,188)
Minimum pension liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance - Beginning of period	2,681	(82)	2,719	(150)
Other comprehensive income (loss), net of tax	342	1,184	304	1,252
Amounts reclassified from accumulated other comprehensive income (loss)			0
Balance - End of period	3,023	1,102	3,023	1,102
Cash flow hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance - Beginning of period	23,104	(694)	(6,694)	(792)
Other comprehensive income (loss), net of tax	3,035	(144)	31,798	(46)
Amounts reclassified from accumulated other comprehensive income (loss)	(186)		849
Balance - End of period	$ 25,953	$ (838)	$ 25,953	$ (838)

Commitments and contingencies77

Commitments and contingencies (Lloyd's syndicate) (Details) - Lloyd's Syndicate 1183 £ in Thousands, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2018USD ($)	Jun. 30, 2018GBP (£)	Dec. 31, 2017USD ($)
Funds at Lloyd's and Lloyd's Central Fund
Maximum premium levies assessable, percent	3.00%	3.00%
Estimated underwriting capacity | £		£ 650,000
Exchange rate	£1 equals $1.32	£1 equals $1.32
Maximum premium levies assessable, amount	$ 25,740		$ 26,325
2018 Underwriting Year
Loss Contingencies [Line Items]
Components of required capital	$ 661,600
2017 Underwriting Year
Loss Contingencies [Line Items]
Components of required capital			$ 583,600

Commitments and contingencies78

Commitments and contingencies (Other commitments) (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Other Commitments [Line Items]
Remaining commitment		$ 206,159	$ 234,775
Capital commitment		268,000	268,000
Fixed maturity investments
Other Commitments [Line Items]
Remaining commitment	[1]	26,477	22,082
Other investments
Other Commitments [Line Items]
Remaining commitment	[2]	83,894	86,697
Investment affiliate
Other Commitments [Line Items]
Remaining commitment		$ 95,788	$ 125,996
[1]	The Company has an outstanding commitment to participate in certain secured loan facilities through participation agreements with an established loan originator
[2]	The Company’s total capital commitments related to other investments as at June 30, 2018 was $268,000 (December 31, 2017: $268,000).

Related party transactions (Det

Related party transactions (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Investments in affiliates	$ 127,247		$ 127,247			$ 100,137
Remaining commitment	206,159		206,159			234,775
Wellington Insurance Company
Related Party Transaction [Line Items]
Gross premiums written	16	$ 1,144	798	$ 4,118
Earned premium adjustments	(282)	1,676	496	2,537
Premiums receivable	542		542			211
Investment affiliate
Related Party Transaction [Line Items]
Investments in affiliates	127,247	103,377	127,247	103,377	$ 113,471	100,137	$ 94,697	$ 100,431
Remaining commitment	95,788		95,788			$ 125,996
Partnership fees incurred	$ 3,767	$ 130	$ 3,899	$ 486

Earnings per share (Details)

Earnings per share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Basic earnings per share
Net (loss) income (attributable) available to Validus common shareholders	$ (52,898)	$ 101,095	$ (56,976)	$ 195,656
Weighted average number of common shares outstanding	79,650,474	79,270,561	79,488,081	79,202,116
Basic earnings per share available to common shareholders	$ (0.66)	$ 1.28	$ (0.72)	$ 2.47
Earnings per diluted share
Net (loss) income (attributable) available to Validus common shareholders	$ (52,898)	$ 101,095	$ (56,976)	$ 195,656
Weighted average number of common shares outstanding	79,650,474	79,270,561	79,488,081	79,202,116
Weighted average number of diluted common shares outstanding	79,650,474	80,872,451	79,488,081	80,861,998
Earnings per diluted share available to common shareholders	$ (0.66)	$ 1.25	$ (0.72)	$ 2.42
Other details:
Anti-dilutive securities excluded from the calculation of diluted earnings per share		412,603		207,054
Stock options
Earnings per diluted share
Share equivalents	0	14,739	0	15,059
Unvested restricted shares
Earnings per diluted share
Share equivalents	0	1,587,151	0	1,644,823

Segment information (Segment re

Segment information (Segment reporting by segment - Underwriting activities) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Gross premiums written	$ 847,206	$ 792,902	$ 2,679,662	$ 1,983,759
Reinsurance premiums ceded	(107,567)	(56,222)	(483,861)	(256,328)
Net premiums written	739,639	736,680	2,195,801	1,727,431
Change in unearned premiums	(3,032)	(105,653)	(840,252)	(521,028)
Net premiums earned	736,607	631,027	1,355,549	1,206,403
Other insurance related income	(16,654)	1,165	8,842	2,401
Total underwriting revenues	719,953	632,192	1,364,391	1,208,804
Losses and loss expenses	476,610	296,149	798,155	565,734
Policy acquisition costs	118,781	117,268	235,237	228,896
General and administrative expenses	120,862	96,349	235,588	184,273
Share compensation expenses	16,040	11,146	25,769	20,637
Total underwriting deductions	732,293	520,912	1,294,749	999,540
Underwriting income	(12,340)	111,280	69,642	209,264
Operating Segments | Reinsurance segment
Segment Reporting Information [Line Items]
Gross premiums written	360,588	330,534	1,126,161	973,675
Reinsurance premiums ceded	(16,368)	(10,278)	(206,562)	(124,724)
Net premiums written	344,220	320,256	919,599	848,951
Change in unearned premiums	(106,697)	(61,948)	(457,324)	(358,988)
Net premiums earned	237,523	258,308	462,275	489,963
Other insurance related income	0	1	2	3
Total underwriting revenues	237,523	258,309	462,277	489,966
Losses and loss expenses	117,338	114,341	220,811	195,222
Policy acquisition costs	52,157	49,966	100,497	93,501
General and administrative expenses	26,522	22,204	55,437	42,173
Share compensation expenses	3,972	2,725	6,635	5,348
Total underwriting deductions	199,989	189,236	383,380	336,244
Underwriting income	$ 37,534	$ 69,073	$ 78,897	$ 153,722
Net premiums written / Gross premiums written	95.50%	96.90%	81.70%	87.20%
Loss and loss expense ratio	49.40%	44.30%	47.80%	39.80%
Policy acquisition cost ratio	22.00%	19.30%	21.70%	19.10%
General and administrative expenses	12.80%	9.70%	13.40%	9.70%
Expense ratio	34.80%	29.00%	35.10%	28.80%
Combined ratio	84.20%	73.30%	82.90%	68.60%
Operating Segments | Insurance segment
Segment Reporting Information [Line Items]
Gross premiums written	$ 384,240	$ 360,057	$ 1,170,035	$ 742,847
Reinsurance premiums ceded	(81,887)	(49,315)	(273,524)	(128,315)
Net premiums written	302,353	310,742	896,511	614,532
Change in unearned premiums	97,446	(5,875)	(197,174)	(30,571)
Net premiums earned	399,799	304,867	699,337	583,961
Other insurance related income	35	728	2,205	1,724
Total underwriting revenues	399,834	305,595	701,542	585,685
Losses and loss expenses	342,854	180,741	526,243	367,351
Policy acquisition costs	57,650	60,137	117,707	121,329
General and administrative expenses	75,110	53,596	143,160	98,872
Share compensation expenses	4,242	3,702	7,231	7,075
Total underwriting deductions	479,856	298,176	794,341	594,627
Underwriting income	$ (80,022)	$ 7,419	$ (92,799)	$ (8,942)
Net premiums written / Gross premiums written	78.70%	86.30%	76.60%	82.70%
Loss and loss expense ratio	85.80%	59.30%	75.20%	62.90%
Policy acquisition cost ratio	14.40%	19.70%	16.80%	20.80%
General and administrative expenses	19.80%	18.80%	21.50%	18.10%
Expense ratio	34.20%	38.50%	38.30%	38.90%
Combined ratio	120.00%	97.80%	113.50%	101.80%

Segment information (Segment 82

Segment information (Segment reporting by segment - Asset management activities (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Share compensation expenses		$ 16,040	$ 11,146	$ 25,769	$ 20,637
Finance expenses		14,310	14,209	28,573	28,152
Tax (benefit)		(7,151)	(987)	(13,984)	(4,536)
Foreign exchange losses		526	7,329	1	5,760
Net investment income		57,560	44,241	109,632	84,455
Gross premiums written		847,206	792,902	2,679,662	1,983,759
Operating Segments | Asset management segment
Segment Reporting Information [Line Items]
Third party management fees		5,685	5,549	11,894	10,193
Related party management fees		436	644	879	1,275
Total fee revenue		6,121	6,193	12,773	11,468
General and administrative expense		4,835	3,549	9,382	7,393
Share compensation expenses		30	83	71	165
Finance expenses		18	44	96	75
Tax (benefit)		2	135	(5)	134
Foreign exchange losses		0	1	1	0
Total expenses		4,885	3,812	9,545	7,767
Income before investment income from funds and sidecars		1,236	2,381	3,228	3,701
Net investment income		1,442	4,143	6,714	8,955
Asset Management segment income		2,678	6,524	9,942	12,656
Gross premiums written		102,378	105,682	389,003	270,608
AlphaCat sidecars | Operating Segments | Asset management segment
Segment Reporting Information [Line Items]
Net investment income	[1]	102	(21)	134	(133)
Gross premiums written		9	0	(134)	66
AlphaCat ILS funds - Lower Risk | Operating Segments | Asset management segment
Segment Reporting Information [Line Items]
Net investment income	[1],[2]	1,773	1,301	3,007	3,490
Gross premiums written		62,577	53,632	172,527	106,540
AlphaCat ILS funds - Higher Risk | Operating Segments | Asset management segment
Segment Reporting Information [Line Items]
Net investment income	[1],[2]	(796)	2,600	3,024	4,967
Gross premiums written		37,514	43,672	203,410	137,208
BetaCat ILS funds | Operating Segments | Asset management segment
Segment Reporting Information [Line Items]
Net investment income	[1]	363	263	549	631
AlphaCat direct | Operating Segments | Asset management segment
Segment Reporting Information [Line Items]
Gross premiums written	[3]	$ 2,278	$ 8,378	$ 13,200	$ 26,794
[1]	The investment income (loss) from funds and sidecars is based on equity accounting.
[2]	Lower risk AlphaCat ILS funds have a maximum permitted portfolio expected loss of less than 7%, whereas higher risk AlphaCat ILS funds have a maximum permitted portfolio expected loss of 7% or greater. The portfolio expected loss represents the average annual loss over the set of simulation scenarios divided by the total limit.
[3]	AlphaCat Direct includes direct investments from a third party investor in AlphaCat Re.

Segment information (Segment 83

Segment information (Segment reporting by segment - Corporate and investments) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017
Segment Reporting Information [Line Items]
Net investment income		$ 57,560	$ 44,241	$ 109,632		$ 84,455
Net realized gains (losses) on investments		(7,394)	2,274	(5,194)		1,110
Change in net unrealized (losses) gains on investments		(10,730)	16,321	(68,111)		29,669
Income from investment affiliates		2,178	9,466	15,246		14,654
Managed investment return		41,614	72,302	51,573	[1]	129,888	[1]
General and administrative expenses		120,862	96,349	235,588		184,273
Share compensation expenses		16,040	11,146	25,769		20,637
Finance expenses		14,310	14,209	28,573		28,152
Dividends on preferred shares		5,828	2,203	11,656		4,406
Tax (benefit)		(7,151)	(987)	(13,984)		(4,536)
Foreign exchange losses		(526)	(7,329)	(1)		(5,760)
Transaction expenses		(3,837)	(4,427)	(11,593)		(4,427)
Net (loss) income (attributable) available to Validus common shareholders		(52,898)	101,095	(56,976)		195,656
Corporate & Investments
Segment Reporting Information [Line Items]
Net investment income	[2]	42,752	38,063	82,543		74,255
Net realized gains (losses) on investments	[2]	(7,432)	2,269	(6,290)		(623)
Change in net unrealized (losses) gains on investments	[2]	(11,392)	15,942	(68,169)		30,291
Income from investment affiliates		2,178	9,466	15,246		14,654
Managed investment return	[1]	26,106	65,740	23,330		118,577
General and administrative expenses		13,523	16,219	25,832		34,180
Share compensation expenses		7,796	4,636	11,832		8,049
Finance expenses	[2]	14,249	14,149	28,339		28,013
Dividends on preferred shares		5,828	2,203	11,656		4,406
Tax (benefit)	[2]	(7,153)	(1,122)	(13,979)		(4,670)
Total expenses		34,243	36,085	63,680		69,978
Foreign exchange losses	[2]	(1,652)	(7,323)	(1,655)		(6,220)
Other income		538	174	582		268
Transaction expenses		(3,837)	(4,427)	(11,593)		(4,427)
Total other items		(4,951)	(11,576)	(12,666)		(10,379)
Net (loss) income (attributable) available to Validus common shareholders		$ (13,088)	$ 18,079	$ (53,016)		$ 38,220
[1]	Net investment return includes net investment income, net realized and change in net unrealized gains (losses) on investments and income (loss) from investment affiliates.
[2]	These items exclude the components which are included in the Asset Management segment income (loss) and amounts which are consolidated from VIEs.

Segment information (Segment co

Segment information (Segment consolidation) (Details) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)segments		Jun. 30, 2017USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segments				3
Underwriting revenues
Gross premiums written		$ 847,206	$ 792,902	$ 2,679,662		$ 1,983,759
Reinsurance premiums ceded		(107,567)	(56,222)	(483,861)		(256,328)
Net premiums written		739,639	736,680	2,195,801		1,727,431
Change in unearned premiums		(3,032)	(105,653)	(840,252)		(521,028)
Net premiums earned		736,607	631,027	1,355,549		1,206,403
Other insurance related income (loss)		(16,654)	1,165	8,842		2,401
Total underwriting revenues		719,953	632,192	1,364,391		1,208,804
Underwriting deductions
Losses and loss expenses		476,610	296,149	798,155		565,734
Policy acquisition costs		118,781	117,268	235,237		228,896
General and administrative expenses		120,862	96,349	235,588		184,273
Share compensation expenses		16,040	11,146	25,769		20,637
Total underwriting deductions		732,293	520,912	1,294,749		999,540
Underwriting income (loss)		(12,340)	111,280	69,642		209,264
Net investment return		41,614	72,302	51,573	[1]	129,888	[1]
Other items		(16,812)	(27,007)	(37,257)	[2]	(37,941)	[2]
(Income) attributable to AlphaCat investors		(29,849)	(11,830)	(40,711)		(19,333)
Net (income) attributable to noncontrolling interests		(35,511)	(43,650)	(100,223)		(86,222)
Net (loss) income (attributable) available to Validus common shareholders		(52,898)	101,095	(56,976)		195,656
Operating Segments | Reinsurance segment
Underwriting revenues
Gross premiums written		360,588	330,534	1,126,161		973,675
Reinsurance premiums ceded		(16,368)	(10,278)	(206,562)		(124,724)
Net premiums written		344,220	320,256	919,599		848,951
Change in unearned premiums		(106,697)	(61,948)	(457,324)		(358,988)
Net premiums earned		237,523	258,308	462,275		489,963
Other insurance related income (loss)		0	1	2		3
Total underwriting revenues		237,523	258,309	462,277		489,966
Underwriting deductions
Losses and loss expenses		117,338	114,341	220,811		195,222
Policy acquisition costs		52,157	49,966	100,497		93,501
General and administrative expenses		26,522	22,204	55,437		42,173
Share compensation expenses		3,972	2,725	6,635		5,348
Total underwriting deductions		199,989	189,236	383,380		336,244
Underwriting income (loss)		37,534	69,073	78,897		153,722
Net (loss) income (attributable) available to Validus common shareholders		37,534	69,073	78,897		153,722
Operating Segments | Insurance segment
Underwriting revenues
Gross premiums written		384,240	360,057	1,170,035		742,847
Reinsurance premiums ceded		(81,887)	(49,315)	(273,524)		(128,315)
Net premiums written		302,353	310,742	896,511		614,532
Change in unearned premiums		97,446	(5,875)	(197,174)		(30,571)
Net premiums earned		399,799	304,867	699,337		583,961
Other insurance related income (loss)		35	728	2,205		1,724
Total underwriting revenues		399,834	305,595	701,542		585,685
Underwriting deductions
Losses and loss expenses		342,854	180,741	526,243		367,351
Policy acquisition costs		57,650	60,137	117,707		121,329
General and administrative expenses		75,110	53,596	143,160		98,872
Share compensation expenses		4,242	3,702	7,231		7,075
Total underwriting deductions		479,856	298,176	794,341		594,627
Underwriting income (loss)		(80,022)	7,419	(92,799)		(8,942)
Net (loss) income (attributable) available to Validus common shareholders		(80,022)	7,419	(92,799)		(8,942)
Operating Segments | Asset management segment
Underwriting revenues
Gross premiums written		102,378	105,682	389,003		270,608
Reinsurance premiums ceded		(9,312)	0	(9,312)		(6,660)
Net premiums written		93,066	105,682	379,691		263,948
Change in unearned premiums		6,219	(37,830)	(185,754)		(131,469)
Net premiums earned		99,285	67,852	193,937		132,479
Other insurance related income (loss)		(12,261)	5,874	15,819		11,035
Total underwriting revenues		87,024	73,726	209,756		143,514
Underwriting deductions
Losses and loss expenses		16,418	1,067	51,101		3,161
Policy acquisition costs		8,974	7,165	17,033		14,066
General and administrative expenses		10,135	9,768	20,343		19,409
Share compensation expenses		30	83	71		165
Total underwriting deductions		35,557	18,083	88,548		36,801
Underwriting income (loss)		51,467	55,643	121,208		106,713
Net investment return	[1]	15,508	6,562	28,243		11,311
Other items	[2]	1,063	(201)	1,425		187
(Income) attributable to AlphaCat investors		(29,849)	(11,830)	(40,711)		(19,333)
Net (income) attributable to noncontrolling interests		(35,511)	(43,650)	(100,223)		(86,222)
Net (loss) income (attributable) available to Validus common shareholders		2,678	6,524	9,942		12,656
Corporate & Investments
Underwriting revenues
Gross premiums written		0	0	0		0
Reinsurance premiums ceded		0	0	0		0
Net premiums written		0	0	0		0
Change in unearned premiums		0	0	0		0
Net premiums earned		0	0	0		0
Other insurance related income (loss)		0	0	0		0
Total underwriting revenues		0	0	0		0
Underwriting deductions
Losses and loss expenses		0	0	0		0
Policy acquisition costs		0	0	0		0
General and administrative expenses		13,523	16,219	25,832		34,180
Share compensation expenses		7,796	4,636	11,832		8,049
Total underwriting deductions		21,319	20,855	37,664		42,229
Underwriting income (loss)		(21,319)	(20,855)	(37,664)		(42,229)
Net investment return	[1]	26,106	65,740	23,330		118,577
Other items	[2]	(17,875)	(26,806)	(38,682)		(38,128)
Net (loss) income (attributable) available to Validus common shareholders		(13,088)	18,079	(53,016)		38,220
Eliminations
Underwriting revenues
Gross premiums written		0	(3,371)	(5,537)		(3,371)
Reinsurance premiums ceded		0	3,371	5,537		3,371
Net premiums written		0	0	0		0
Change in unearned premiums		0	0	0		0
Net premiums earned		0	0	0		0
Other insurance related income (loss)		(4,428)	(5,438)	(9,184)		(10,361)
Total underwriting revenues		(4,428)	(5,438)	(9,184)		(10,361)
Underwriting deductions
Losses and loss expenses		0	0	0		0
Policy acquisition costs		0	0	0		0
General and administrative expenses		(4,428)	(5,438)	(9,184)		(10,361)
Share compensation expenses		0	0	0		0
Total underwriting deductions		(4,428)	(5,438)	(9,184)		(10,361)
Underwriting income (loss)		0	0	0		0
Net investment return	[1]	0	0	0		0
Other items	[2]	0	0	0		0
Net (loss) income (attributable) available to Validus common shareholders		$ 0	$ 0	$ 0		$ 0
[1]	Net investment return includes net investment income, net realized and change in net unrealized gains (losses) on investments and income (loss) from investment affiliates.
[2]	Other items includes finance expenses, transaction expenses, dividends on preferred shares, tax benefit (expense), foreign exchange gains (losses), income (loss) from operating affiliate and other income (loss).

Segment information (Gross prem

Segment information (Gross premiums written by geographic location and segment) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ 847,206	$ 792,902	$ 2,679,662		$ 1,983,759
Percent of gross premiums written	100.00%	100.00%	100.00%		100.00%
United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ 408,313	$ 332,452	$ 1,198,707		$ 774,771
Percent of gross premiums written	48.20%	41.90%	44.70%		39.10%
Worldwide excluding United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ 54,290	$ 43,543	$ 148,726	[1]	$ 118,324	[1]
Percent of gross premiums written	6.40%	5.50%	5.60%	[1]	5.90%	[1]
Australia and New Zealand
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ (2,959)	$ 7,155	$ 6,354		$ 11,118
Percent of gross premiums written	(0.30%)	0.90%	0.20%		0.60%
Europe
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ 10,139	$ 6,864	$ 54,019		$ 47,956
Percent of gross premiums written	1.20%	0.90%	2.00%		2.40%
Latin America and Caribbean
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ 36,010	$ 35,458	$ 60,994		$ 66,105
Percent of gross premiums written	4.30%	4.50%	2.30%		3.30%
Japan
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ 47,513	$ 45,342	$ 50,960		$ 49,491
Percent of gross premiums written	5.60%	5.70%	1.90%		2.50%
Canada
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ 6,245	$ 4,392	$ 10,913		$ 7,199
Percent of gross premiums written	0.70%	0.60%	0.40%		0.40%
Rest of the world
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ 30,530	$ 28,002	$ 76,048	[2]	$ 63,497	[2]
Percent of gross premiums written	3.60%	3.50%	2.90%	[2]	3.20%	[2]
Sub-total, non United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ 181,768	$ 170,756	$ 408,014		$ 363,690
Percent of gross premiums written	21.50%	21.60%	15.30%		18.30%
Worldwide including United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ 119,574	$ 110,111	$ 509,140	[1]	$ 356,408	[1]
Percent of gross premiums written	14.10%	13.90%	19.00%	[1]	18.00%	[1]
Other location non-specific
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ 137,551	$ 179,583	$ 563,801	[3]	$ 488,890	[3]
Percent of gross premiums written	16.20%	22.60%	21.00%	[3]	24.60%	[3]
Operating Segments | Reinsurance segment
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ 360,588	$ 330,534	$ 1,126,161		$ 973,675
Operating Segments | Reinsurance segment | United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	149,298	108,727	349,472		332,655
Operating Segments | Reinsurance segment | Worldwide excluding United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	12,962	5,378	52,287	[1]	40,586	[1]
Operating Segments | Reinsurance segment | Australia and New Zealand
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	33	3,388	1,169		4,177
Operating Segments | Reinsurance segment | Europe
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	3,091	1,168	41,073		33,113
Operating Segments | Reinsurance segment | Latin America and Caribbean
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	10,581	11,320	17,120		21,280
Operating Segments | Reinsurance segment | Japan
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	43,467	40,832	45,567		42,783
Operating Segments | Reinsurance segment | Canada
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	4,955	3,267	8,690		5,625
Operating Segments | Reinsurance segment | Rest of the world
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	5,971	5,062	24,269	[2]	20,165	[2]
Operating Segments | Reinsurance segment | Sub-total, non United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	81,060	70,415	190,175		167,729
Operating Segments | Reinsurance segment | Worldwide including United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	59,259	56,169	178,068	[1]	151,970	[1]
Operating Segments | Reinsurance segment | Other location non-specific
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	70,971	95,223	408,446	[3]	321,321	[3]
Operating Segments | Insurance segment
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	384,240	360,057	1,170,035		742,847
Operating Segments | Insurance segment | United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	188,253	157,048	748,975		347,236
Operating Segments | Insurance segment | Worldwide excluding United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	41,430	37,295	93,662	[1]	69,833	[1]
Operating Segments | Insurance segment | Australia and New Zealand
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	(2,992)	1,764	5,185		4,938
Operating Segments | Insurance segment | Europe
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	7,048	5,711	12,608		14,392
Operating Segments | Insurance segment | Latin America and Caribbean
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	25,429	24,092	43,874		44,779
Operating Segments | Insurance segment | Japan
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	2,213	1,848	3,129		2,853
Operating Segments | Insurance segment | Canada
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	931	995	1,864		1,444
Operating Segments | Insurance segment | Rest of the world
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	24,559	22,940	51,779	[2]	43,332	[2]
Operating Segments | Insurance segment | Sub-total, non United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	98,618	94,645	212,101		181,571
Operating Segments | Insurance segment | Worldwide including United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	30,789	24,005	57,444	[1]	51,192	[1]
Operating Segments | Insurance segment | Other location non-specific
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	66,580	84,359	151,515	[3]	162,848	[3]
Operating Segments | Asset management segment
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	102,378	105,682	389,003		270,608
Operating Segments | Asset management segment | United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	70,762	70,048	101,785		98,251
Operating Segments | Asset management segment | Worldwide excluding United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	(102)	870	2,777	[1]	7,905	[1]
Operating Segments | Asset management segment | Australia and New Zealand
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	2,003	0		2,003
Operating Segments | Asset management segment | Europe
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	(15)	338		451
Operating Segments | Asset management segment | Latin America and Caribbean
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	46	0		46
Operating Segments | Asset management segment | Japan
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	1,833	2,662	2,264		3,855
Operating Segments | Asset management segment | Canada
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	359	130	359		130
Operating Segments | Asset management segment | Rest of the world
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	0	0	[2]	0	[2]
Operating Segments | Asset management segment | Sub-total, non United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	2,090	5,696	5,738		14,390
Operating Segments | Asset management segment | Worldwide including United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	29,526	29,937	277,640	[1]	153,246	[1]
Operating Segments | Asset management segment | Other location non-specific
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	1	3,840	[3]	4,721	[3]
Eliminations
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	(3,371)	(5,537)		(3,371)
Eliminations | United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	(3,371)	(1,525)		(3,371)
Eliminations | Worldwide excluding United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	0	0	[1]	0	[1]
Eliminations | Australia and New Zealand
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	0	0		0
Eliminations | Europe
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	0	0		0
Eliminations | Latin America and Caribbean
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	0	0		0
Eliminations | Japan
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	0	0		0
Eliminations | Canada
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	0	0		0
Eliminations | Rest of the world
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	0	0	[2]	0	[2]
Eliminations | Sub-total, non United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	0	0		0
Eliminations | Worldwide including United States
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	0	0	(4,012)	[1]	0	[1]
Eliminations | Other location non-specific
Gross premiums written allocated to the territory of coverage exposure
Gross premiums written	$ 0	$ 0	$ 0	[3]	$ 0	[3]
[1]	Represents risks in two or more geographic zones.
[2]	Represents risks in one geographic zone.
[3]	The other locations non-specific category refers to business for which an analysis of exposure by geographic zone is not applicable since these exposures can span multiple geographic areas and, in some instances, are not fixed locations.

Subsequent events (Details)

Subsequent events (Details)	Jun. 30, 2018
2010 Senior Notes Due 2040
Subsequent Event [Line Items]
Fixed interest rate (in percent)	8.875%	[1]
[1]	Fixed interest rate.