Validus 10-Q 7 Nov 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Nov. 05, 2014
Document and Entity Information [Abstract]	'	'
Entity Registrant Name	'VALIDUS HOLDINGS LTD	'
Entity Central Index Key	'0001348259	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Amendment Flag	'false	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
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	'	87,376,871

Consolidated_Balance_Sheets_Un

Consolidated Balance Sheets (Unaudited) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Assets	'		'
Fixed maturities, at fair value (amortized cost: 2014—$4,668,585; 2013—$5,522,853)	$4,670,173		$5,542,258
Short-term investments, at fair value (amortized cost: 2014—$1,684,997; 2013—$751,734)	1,684,982	[1]	751,778	[2]
Other investments, at fair value (cost: 2014—$714,508; 2013—$637,728)	718,633		618,316
Cash and cash equivalents	843,747		1,056,346
Total investments and cash	7,917,535		7,968,698
Investments in affiliates	217,612		141,243
Premiums receivable	936,306		697,233
Deferred acquisition costs	186,277		134,269
Prepaid reinsurance premiums	129,809		103,251
Securities lending collateral	9,056		3,392
Loss reserves recoverable	298,502		370,154
Paid losses recoverable	62,991		80,080
Intangible assets	103,287		106,407
Goodwill	20,393		20,393
Accrued investment income	15,415		18,876
Other assets	155,867		202,436
Total assets	10,053,050		9,846,432
Liabilities	'		'
Reserve for losses and loss expenses	2,752,168		3,030,399
Unearned premiums	1,158,429		824,496
Reinsurance balances payable	141,482		154,874
Securities lending payable	9,522		3,858
Deferred income taxes	11,687		19,086
Net payable for investments purchased	54,735		19,383
Accounts payable and accrued expenses	186,649		278,187
Notes payable to operating affiliates	655,976		439,272
Senior notes payable	247,279		247,198
Debentures payable	539,953		541,416
Total liabilities	5,757,880		5,558,169
Commitments and contingent liabilities	'		'
Redeemable noncontrolling interest	70,473		86,512
Shareholders' equity	'		'
Common shares, 571,428,571 authorized, par value $0.175 (Issued: 2014—155,253,556; 2013—154,488,497; Outstanding: 2014—89,112,271; 2013—96,044,312)	27,169		27,036
Treasury shares (2014—66,141,285; 2013—58,444,185)	-11,575		-10,228
Additional paid-in-capital	1,413,145		1,677,894
Accumulated other comprehensive loss	-2,738		-617
Retained earnings	2,276,409		2,010,009
Total shareholders' equity available to Validus	3,702,410		3,704,094
Noncontrolling interest	522,287		497,657
Total shareholders' equity	4,224,697		4,201,751
Total liabilities, noncontrolling interests and shareholders’ equity	$10,053,050		$9,846,432
[1]	Included in the short-term investments balance are investments held by one AlphaCat ILS fund which is consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
[2]	Included in the short-term investments balance are investments held by two AlphaCat ILS funds which are consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Assets	'		'
Fixed maturities, at amortized cost or cost	$4,668,585		$5,522,853
Short-term investments, at amortized cost or cost	1,684,997	[1]	751,734	[2]
Other investments, at amortized cost or cost	$714,508		$637,728
Shareholders' equity	'		'
Common shares, shares authorized	571,428,571		571,428,571
Common shares, par value	$0.18		$0.18
Common shares, shares issued	155,253,556		154,488,497
Common shares, shares outstanding	89,112,271		96,044,312
Treasury stock, common shares	66,141,285		58,444,185
[1]	Included in the short-term investments balance are investments held by one AlphaCat ILS fund which is consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
[2]	Included in the short-term investments balance are investments held by two AlphaCat ILS funds which are consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended				9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Revenues	'		'		'		'
Gross premiums written	$358,974		$356,760		$2,026,639		$2,163,833
Reinsurance premiums ceded	-30,137		-39,415		-275,610		-348,027
Net premiums written	328,837		317,345		1,751,029		1,815,806
Change in unearned premiums	165,859		213,943		-307,373		-205,999
Net premiums earned	494,696		531,288		1,443,656		1,609,807
Net investment income	25,261		20,009		69,909		71,868
Net realized gains (losses) on investments	4,595		-6,320		16,193		-1,190
Change in net unrealized (losses) gains on investments	-84,974	[1]	69,967	[1]	16,146	[1]	-78,618	[1]
Income from investment affiliate	1,754		1,044		7,881		4,274
Other (loss) income	-4,080		-2,806		14,985		4,297
Foreign exchange (losses) gains	-11,441		6,036		-14,761		4,735
Total revenues	425,811		619,218		1,554,009		1,615,173
Expenses	'		'		'		'
Losses and loss expenses	224,125		177,965		545,541		587,780
Policy acquisition costs	86,404		94,900		251,006		275,663
General and administrative expenses	83,319		81,089		231,606		232,335
Share compensation expenses	8,764		10,527		24,252		19,483
Finance expenses	15,354		15,317		47,380		47,252
Transaction expenses	149	[2]	0		3,401	[2]	0
Total expenses	418,115		379,798		1,103,186		1,162,513
Income before taxes, income from operating affiliates and (income) attributable to operating affiliate investors	7,696		239,420		450,823		452,660
Tax benefit (expense)	953		-5		-398		220
Income from operating affiliates	3,761		1,463		13,580		8,779
(Income) attributable to operating affiliate investors	-25,807		-11,815		-82,833		-42,156
Net (loss) income	-13,397		229,063		381,172		419,503
Net loss (income) attributable to noncontrolling interest	53,069		-45,694		-25,745		17,831
Net income available to Validus	39,672		183,369		355,427		437,334
Other comprehensive (loss) income	'		'		'		'
Foreign currency translation adjustments	-5,198		4,390		-2,121		-5,209
Other comprehensive (loss) income	-5,198		4,390		-2,121		-5,209
Comprehensive income available to Validus	$34,474		$187,759		$353,306		$432,125
Weighted average number of common shares and common share equivalents outstanding	'		'		'		'
Basic	90,593,329		99,834,563		91,665,950		103,451,396
Diluted	91,939,610		103,613,766		95,937,641		105,264,913
Basic earnings per share available to common shareholders	$0.42		$1.82		$3.83		$4.06
Earnings per diluted share available to common shareholders	$0.41		$1.77		$3.70		$3.99
Cash dividends declared per share	$0.30		$0.30		$0.90		$2.90
[1]	Includes change in net unrealized gains (losses) and realized gains on investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and is included in the Consolidated Statements of Comprehensive Income as net loss (income) attributable to noncontrolling interest.
[2]	The transaction expenses relate to costs incurred in connection with the acquisition of Western World, which was completed on October 2, 2014. Western World results have not been included in the Company's consolidated results for the three months ended September 30, 2014. Transaction expenses are primarily comprised of legal, financial advisory and audit related services.

Consolidated_Statements_of_Sha

Consolidated Statements of Shareholders' Equity (Unaudited) (USD $)	Total	Common shares	Treasury shares	Additional paid-in capital	Accumulated other comprehensive loss	Retained earnings
In Thousands
Balance - Beginning of period at Dec. 31, 2012	'	$26,722	($7,836)	$2,160,478	($2,953)	$1,844,416
Common shares issued (redeemed), net	'	296	'	-134	'	'
Repurchase of common shares	'	'	-1,699	-355,485	'	'
Share compensation expenses	'	'	'	19,483	'	'
Other comprehensive loss	-5,209	'	'	'	-5,209	'
Dividends	'	'	'	'	'	-331,251
Net income	419,503	'	'	'	'	419,503
Net loss (income) attributable to noncontrolling interest	17,831	'	'	'	'	17,831
Amounts reclassified to retained earnings	'	'	'	'	4,290	-4,290
Total shareholders' equity at Sep. 30, 2013	4,256,095	'	'	'	'	'
Noncontrolling interest at Sep. 30, 2013	471,933	'	'	'	'	'
Balance - End of period at Sep. 30, 2013	3,784,162	27,018	-9,535	1,824,342	-3,872	1,946,209
Balance - Beginning of period at Dec. 31, 2013	3,704,094	27,036	-10,228	1,677,894	-617	2,010,009
Common shares issued (redeemed), net	'	133	'	-3,822	'	'
Repurchase of common shares	'	'	-1,347	-285,179	'	'
Share compensation expenses	'	'	'	24,252	'	'
Other comprehensive loss	-2,121	'	'	'	-2,121	'
Dividends	'	'	'	'	'	-89,027
Net income	381,172	'	'	'	'	381,172
Net loss (income) attributable to noncontrolling interest	-25,745	'	'	'	'	-25,745
Amounts reclassified to retained earnings	'	'	'	'	0	0
Total shareholders' equity at Sep. 30, 2014	4,224,697	'	'	'	'	'
Noncontrolling interest at Sep. 30, 2014	522,287	'	'	'	'	'
Balance - End of period at Sep. 30, 2014	$3,702,410	$27,169	($11,575)	$1,413,145	($2,738)	$2,276,409

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (Unaudited) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013
Cash flows provided by (used in) operating activities	'		'
Net income	$381,172		$419,503
Adjustments to reconcile net income to cash provided by (used in) operating activities:	'		'
Share compensation expenses	24,252		19,483
Gain on sale of subsidiary	-709		0
Gain on deconsolidation of subsidiary	-1,372		0
Amortization of discount on senior notes	81		81
Income from investment affiliate	-7,881		-4,274
Net realized (gains) losses on investments	-16,193		1,190
Change in net unrealized (gains) losses on investments	-16,146	[1]	78,618	[1]
Amortization of intangible assets	3,120		3,120
Income from operating affiliates	-13,580		-8,779
Foreign exchange losses included in net income	10,841		4,927
Amortization of premium on fixed maturities	11,922		14,870
Change in:	'		'
Premiums receivable	-241,175		-226,154
Deferred acquisition costs	-52,008		-19,951
Prepaid reinsurance premiums	-26,558		-69,469
Loss reserves recoverable	70,444		20,411
Paid losses recoverable	17,245		16,218
Income taxes recoverable	0		-3,099
Accrued investment income	3,431		3,466
Other assets	30,125		-11,214
Reserve for losses and loss expenses	-271,063		-293,673
Unearned premiums	333,933		275,468
Reinsurance balances payable	-12,836		-634
Deferred income taxes	-7,385		2,565
Accounts payable and accrued expenses	-70,809		-17,783
Net cash provided by operating activities	148,851		204,890
Cash flows provided by (used in) investing activities	'		'
Proceeds on sales of investments	3,587,124		3,598,080
Proceeds on maturities of investments	466,872		406,079
Purchases of fixed maturities	-3,161,908		-4,414,320
(Purchases) sales of short-term investments, net	-961,264		348,554
Purchases of other investments, net	-69,932		-21,793
Increase in securities lending collateral	-5,664		-796
Redemption of investment in operating affiliates	58,547		86,657
Purchase of investment in investment affiliate	0		-13,089
Proceeds sale of subsidiary	16,459		0
Net cash used in investing activities	-69,766		-10,628
Cash flows provided by (used in) financing activities	'		'
Net proceeds on issuance of notes payable to operating affiliates	43,175		418,299
(Redemption) issuance of common shares, net	-3,689		162
Purchases of common shares under share repurchase program	-286,526		-357,184
Dividends paid	-89,719		-329,201
Increase in securities lending payable	5,664		796
Investment in third party redeemable noncontrolling interest	50,704		62,790
Investment in third party noncontrolling interest	0		58,500
Net cash used in financing activities	-280,391		-145,838
Effect of foreign currency rate changes on cash and cash equivalents	-11,293		-13,185
Net (decrease) increase in cash	-212,599		35,239
Cash and cash equivalents - beginning of period	1,056,346		1,219,379
Cash and cash equivalents - end of period	843,747		1,254,618
Taxes paid during the period	7,286		5,325
Interest paid during the period	$46,421		$44,112
[1]	Includes change in net unrealized gains (losses) and realized gains on investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and is included in the Consolidated Statements of Comprehensive Income as net loss (income) attributable to noncontrolling interest.

Basis_of_preparation_and_conso

Basis of preparation and consolidation	9 Months Ended
	Sep. 30, 2014
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") include Validus Holdings, Ltd. and its wholly and majority owned subsidiaries (together the "Company") and 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 the Company's Annual Report on Form 10-K for the year ended December 31, 2013, as filed with the U.S. Securities and Exchange Commission (the "SEC").
	In the opinion of management, these Consolidated Financial Statements reflect all adjustments (including normal recurring adjustments) considered necessary for a fair presentation of the Company's financial position and results of operations as at the end of and for the periods presented. To facilitate comparison of information, certain amounts in prior periods have been reclassified to conform to current period presentation. The consolidated statement of cash flows for the nine months ended September 30, 2013 includes a reclassification of $19,400 that increased net cash flows used in financing activities and net cash flows provided by operating activities to revise the presentation of subscriptions received in advance from third party investors. For the three and nine months ended September 30, 2013, $11,815 and $42,156 respectively, have been reclassified into income attributable to operating affiliate investors from finance expenses to conform to current period presentation. 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 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 management believes that the amounts included in the Consolidated Financial Statements reflect its best estimates and assumptions, actual results could differ materially from those estimates. The Company’s principal estimates include:
	•reserve for losses and loss expenses;
	•premium estimates for business written on a line slip or proportional basis;
	•the valuation of goodwill and intangible assets;
	•reinsurance recoverable balances including the provision for uncollectible amounts; and
	•investment valuation of financial assets.
	The term “ASC” used in these notes refers to Accounting Standard Codification issued by the U.S. Financial Accounting Standards Board (“FASB”).

Recent_accounting_pronouncemen

Recent accounting pronouncements	9 Months Ended
	Sep. 30, 2014
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]	'
Recent accounting pronouncements	'
	Recent accounting pronouncements
	Adoption of New Accounting Standards
	Parent’s Accounting for the Cumulative Translation Adjustment upon Derecognition of Certain Subsidiaries or Groups of Assets within a Foreign Entity or of an Investment in a Foreign Entity
	In March 2013, the FASB issued Accounting Standard Update No. 2013-05, “Parent’s Accounting for the Cumulative Translation Adjustment upon Derecognition of Certain Subsidiaries or Groups of Assets within a Foreign Entity or of an Investment in a Foreign Entity” (ASU 2013-05). The objective of this Update is to resolve the diversity in practice about whether Subtopic 810-10, Consolidation-Overall, or Subtopic 830-30, Foreign Currency Matters-Translation of Financial Statements, applies to the release of the cumulative translation adjustment into net income when a parent either sells a part or all of its investment in a foreign entity or no longer holds a controlling financial interest in a subsidiary within a foreign entity. The amendments became effective for the Company on January 1, 2014. Adoption of this guidance did not have a material impact on the Company’s Consolidated Financial Statements.
	Financial Services - Investment Companies - Amendments to the Scope, Measurement, and Disclosure Requirements
	In June 2013, the FASB issued Accounting Standard Update No. 2013-08, “Financial Services - Investment Companies - Amendments to the Scope, Measurement, and Disclosure Requirements” (ASU 2013-08). The amendments in this Update change the assessment of whether an entity is an investment company by developing a new two-tiered approach for that assessment, which requires an entity to possess certain fundamental characteristics while allowing judgment in assessing other typical characteristics. The new approach requires an entity to assess all of the characteristics of an investment company and consider its purpose and determine whether it is an investment company. The amendments became effective for the Company on January 1, 2014. The Company performed an assessment and has concluded that the AlphaCat ILS funds meet the characteristics outlined in this Update and therefore will continue to be treated as investment companies.
	Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists
	In July 2013, the FASB issued Accounting Standard Update No. 2013-11 “Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists” (ASU 2013-11). This Update applies to all entities that have unrecognized tax benefits when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists at the reporting date. An unrecognized tax benefit should be presented in the financial statements as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward. To the extent a net operating loss carryforward is not available to settle any additional income taxes that would result from the disallowance of a tax position at the reporting date, the unrecognized tax benefit should be presented in the financial statements as a liability and should not be combined with deferred tax assets. The amendments became effective for the Company on January 1, 2014. Adoption of this guidance did not have a material impact on the Company’s Consolidated Financial Statements.
	Recently Issued Accounting Standards Not Yet Adopted
	In May 2014, the FASB issued Accounting Standard Update No. 2014-09, “Revenue from Contracts with Customers” (ASU 2014-09). The guidance in this Update affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of nonfinancial assets, unless those contracts are within the scope of other standards (for example, insurance contracts or lease contracts). The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The amendments in this Update are effective for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. Earlier adoption is not permitted. The Company is currently evaluating the impact of this guidance on the Company’s Consolidated Financial Statements.
	In June 2014, the FASB issued Accounting Standard Update No. 2014-12, “Compensation - Stock Compensation (Topic 718) - Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period” (ASU 2014-12). The amendments in this Update apply to all reporting entities that grant their employees share-based payments in which the terms of the award provide that a performance target that affects vesting could be achieved after the requisite service period. That is the case when an employee is eligible to retire or otherwise terminate employment before the end of the period in which a performance target (for example, an initial public offering or a profitability target) could be achieved and still be eligible to vest in the award if and when the performance target is achieved. The amendments in this Update are effective for annual reporting periods beginning after December 15, 2015, including interim periods within that reporting period. Earlier adoption is permitted. The Company is currently evaluating the impact of this guidance; however, it is not expected to have a material impact on the Company's Consolidated Financial Statements.
	In August 2014, the FASB issued Accounting Standard Update 2014-13, “Consolidation (Topic 810) - Measuring the Financial Assets and the Financial Liabilities of a Consolidated Collateralized Financing Entity” (ASU 2014-13). The fair value of the financial assets of a collateralized financing entity, as determined under GAAP, may differ from the fair value of its financial liabilities even when the financial liabilities have recourse only to the financial assets. The amendments in this Update provide an alternative to Topic 820 for measuring the financial assets and the financial liabilities of a consolidated collateralized financing entity to eliminate that difference. The amendments in this Update are effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015. Early adoption is permitted as of the beginning of an annual period. The Company is currently evaluating the impact of this guidance on the Company’s Consolidated Financial Statements.
	In August 2014, the FASB issued Accounting Standard Update 2014-15, “Presentation of Financial Statements - Going Concern - Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern” (ASU 2014-15). The amendments in this Update require management to assess an entity’s ability to continue as a going concern by incorporating and expanding upon certain principles that are currently in U.S. auditing standards. The amendments in this Update are effective for the annual period ending after December 15, 2016, and for annual periods and interim periods thereafter. Early application is permitted. The Company is currently evaluating the impact of this guidance; however, it will not have a material impact on the Company's Consolidated Financial Statements.

Investments

Investments	9 Months Ended
	Sep. 30, 2014
Investments [Abstract]	'
Investments	'
	Investments
	(a)	Fixed maturity, short-term and other investments
	The Company's investments in fixed maturities, short-term investments and other investments are classified as trading and carried at fair value, with related changes in net unrealized gains or losses included in earnings.
	The amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments at September 30, 2014 were as follows:
		Amortized Cost or Cost			Gross Unrealized Gains				Gross Unrealized Losses				Estimated Fair Value
	U.S. government and government agency	$	786,318		$	1,735			$	(1,798	)		$	786,255
	Non-U.S. government and government agency	383,378			1,775				(3,956		)		381,197
	U.S. states, municipalities and political subdivisions	73,996			557				(188		)		74,365
	Agency residential mortgage-backed securities	368,646			7,877				(1,296		)		375,227
	Non-agency residential mortgage-backed securities	17,370			238				(409		)		17,199
	U.S. corporate	1,168,304			5,601				(4,987		)		1,168,918
	Non-U.S. corporate	593,619			4,071				(3,055		)		594,635
	Bank loans	488,904			616				(5,732		)		483,788
	Catastrophe bonds	47,574			1,305				(541		)		48,338
	Asset-backed securities	566,135			981				(664		)		566,452
	Commercial mortgage-backed securities	174,341			48				(590		)		173,799
	Total fixed maturities	4,668,585			24,804				(23,216		)		4,670,173
	Total short-term investments (b)	1,684,997			4				(19		)		1,684,982
	Other investments
	Fund of hedge funds	2,802			162				(921		)		2,043
	Hedge funds (a)	570,372			101,610				(104,142		)		567,840
	Private equity investments	11,295			3,832				(108		)		15,019
	Investment funds	123,840			350				—				124,190
	Mutual funds	6,199			3,342				—				9,541
	Total other investments	714,508			109,296				(105,171		)		718,633
	Total investments including noncontrolling interests	$	7,068,090		$	134,104			$	(128,406	)		$	7,073,788
	Noncontrolling interest (a)	$	(502,830	)	$	(86,263	)		$	93,728			$	(495,365	)
	Redeemable noncontrolling interest (b)	$	(11,637	)	$	—			$	—			$	(11,637	)
	Total investments excluding noncontrolling interests	$	6,553,623		$	47,841			$	(34,678	)		$	6,566,786
	(a)	Included in the hedge funds balance are investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.
	(b)	Included in the short-term investments balance are investments held by one AlphaCat ILS fund which is consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
	The amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments at December 31, 2013 were as follows:
		Amortized Cost or Cost			Gross Unrealized Gains				Gross Unrealized Losses				Estimated Fair Value
	U.S. government and government agency	$	1,368,826		$	2,589			$	(6,736	)		$	1,364,679
	Non-U.S. government and government agency	454,578			6,511				(2,021		)		459,068
	U.S. states, municipalities and political subdivisions	42,978			459				(317		)		43,120
	Agency residential mortgage-backed securities	305,450			8,310				(2,261		)		311,499
	Non-agency residential mortgage-backed securities	16,530			143				(914		)		15,759
	U.S. corporate	1,328,960			9,208				(5,684		)		1,332,484
	Non-U.S. corporate	711,581			5,917				(3,173		)		714,325
	Bank loans	712,859			5,659				(1,402		)		717,116
	Catastrophe bonds	72,000			2,551				—				74,551
	Asset-backed securities	509,091			1,409				(843		)		509,657
	Total fixed maturities	5,522,853			42,756				(23,351		)		5,542,258
	Total short-term investments (b)	751,734			45				(1		)		751,778
	Other investments
	Fund of hedge funds	3,141			83				(921		)		2,303
	Hedge funds (a)	584,518			71,641				(95,076		)		561,083
	Private equity investments	12,333			1,410				(258		)		13,485
	Investment funds	31,537			92				—				31,629
	Mutual funds	6,199			3,617				—				9,816
	Total other investments	637,728			76,843				(96,255		)		618,316
	Total investments including noncontrolling interests	$	6,912,315		$	119,644			$	(119,607	)		$	6,912,352
	Noncontrolling interest (a)	(512,121		)	(62,850		)		85,569				(489,402		)
	Redeemable noncontrolling interest (b)	$	(18,365	)	$	—			$	—			$	(18,365	)
	Total investments excluding noncontrolling interests	$	6,381,829		$	56,794			$	(34,038	)		$	6,404,585
	(a)	Included in the hedge funds balance are investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.
	(b)	Included in the short-term investments balance are investments held by two AlphaCat ILS funds which are consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
	As of June 30, 2014, the Company changed the methodology of assigning investment ratings to its fixed maturities portfolio. In prior periods, investment ratings were the lower of Moody’s or Standard & Poor’s rating for each investment security, presented in Standard & Poor’s equivalent rating. As of June 30, 2014, investment ratings are the median of Moody’s, Standard & Poor’s and Fitch, presented in Standard & Poor’s equivalent rating. For investments where only two ratings are available, the lower of the two ratings shall apply, presented in Standard & Poor’s equivalent rating. For investments where Moody’s and Standard & Poor’s ratings are not available, Fitch ratings are used and presented in Standard & Poor’s equivalent rating. The December 31, 2013 comparative data was restated as a result, to conform to current period presentation.
	The following table sets forth certain information regarding the investment ratings of the Company’s fixed maturities portfolio as at September 30, 2014 and December 31, 2013.
		September 30, 2014						December 31, 2013
		Estimated Fair Value			% of Total			Estimated Fair Value				% of Total
	AAA	$	2,174,861		46.6	%		$	2,510,781			45.3	%
AA	594,858			12.7	%		696,998				12.6	%
A	960,153			20.6	%		1,233,716				22.3	%
BBB	363,626			7.8	%		323,085				5.8	%
Total investment-grade fixed maturities	4,093,498			87.7	%		4,764,580				86	%
BB	283,954			6.1	%		354,992				6.4	%
B	269,380			5.8	%		383,639				6.9	%
CCC	1,341			—	%		2,453				—	%
CC	2,330			—	%		2,496				0.1	%
C	146			—	%		235				—	%
D/NR	19,524			0.4	%		33,863				0.6	%
Total non-investment grade fixed maturities	576,675			12.3	%		777,678				14	%
Total fixed maturities	$	4,670,173		100	%		$	5,542,258			100	%
The amortized cost and estimated fair value amounts for fixed maturities held at September 30, 2014 and December 31, 2013 are shown below by contractual maturity. Actual maturity may differ from contractual maturity because certain borrowers may have the right to call or prepay certain obligations with or without call or prepayment penalties.
	September 30, 2014							December 31, 2013
	Amortized Cost			Estimated Fair Value				Amortized Cost				Estimated Fair Value
Due in one year or less	$	277,213		$	278,507			$	688,855			$	692,768
Due after one year through five years	2,678,792			2,679,938				3,603,459				3,613,847
Due after five years through ten years	496,922			491,364				396,389				395,633
Due after ten years	89,166			87,687				3,079				3,095
	3,542,093			3,537,496				4,691,782				4,705,343
Asset-backed and mortgage-backed securities	1,126,492			1,132,677				831,071				836,915
Total fixed maturities	$	4,668,585		$	4,670,173			$	5,522,853			$	5,542,258
(b)	Net investment income
Net investment income was derived from the following sources:
	Three Months Ended							Nine Months Ended
	September 30, 2014			September 30, 2013				September 30, 2014				September 30, 2013
Fixed maturities and short-term investments	$	22,544		$	20,936			$	68,048			$	74,618
Other investments	2,879			—				2,879				—
Cash and cash equivalents	1,581			1,079				4,534				3,241
Securities lending income	1			3				5				3
Total gross investment income	27,005			22,018				75,466				77,862
Investment expenses	(1,744		)	(2,009		)		(5,557		)		(5,994		)
Total net investment income	$	25,261		$	20,009			$	69,909			$	71,868
Net investment income from other investments includes distributed and undistributed net income from certain investment funds.
(c)	Net realized gains (losses) and change in net unrealized (losses) gains on investments
The following represents an analysis of net realized gains (losses) and the change in net unrealized (losses) gains on investments:
	Three Months Ended							Nine Months Ended
	September 30, 2014			September 30, 2013				September 30, 2014				September 30, 2013
Fixed maturities, short-term and other investments
Gross realized gains (a)	$	8,075		$	7,706			$	23,184			$	25,578
Gross realized (losses)	(3,480		)	(14,026		)		(6,991		)		(26,768		)
Net realized gains (losses) on investments	4,595			(6,320		)		16,193				(1,190		)
Change in net unrealized (losses) gains on investments (a)	(84,974		)	69,967				16,146				(78,618		)
Total net realized gains (losses) and change in net unrealized (losses) gains on investments including noncontrolling interest	(80,379		)	63,647				32,339				(79,808		)
Noncontrolling interest (a)	52,595			(42,579		)		(22,613		)		25,766
Total net realized gains (losses) and change in net unrealized (losses) gains on investments excluding noncontrolling interest	$	(27,784	)	$	21,068			$	9,726			$	(54,042	)
(a)	Includes change in net unrealized gains (losses) and realized gains on investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and is included in the Consolidated Statements of Comprehensive Income as net loss (income) attributable to noncontrolling interest.
(d)	Pledged investments
The following tables outline investments pledged as collateral under the Company's credit facilities. For further details on the credit facilities, please refer to Note 12: “Debt and financing arrangements.”
		September 30, 2014
Description		Commitment			Issued and Outstanding				Investments and cash pledged as collateral
$400,000 syndicated unsecured letter of credit facility		$	400,000		$	—			$	—
$525,000 syndicated secured letter of credit facility		525,000			301,340				393,720
$200,000 secured bi-lateral letter of credit facility		200,000			19,743				35,414
Talbot FAL facility		25,000			25,000				31,054
PaCRe senior secured letter of credit facility		10,000			294				—
AlphaCat Re secured letter of credit facility		30,000			30,000				30,059
IPC bi-lateral facility		40,000			16,975				96,633
$375,000 Flagstone bi-lateral facility		375,000			288,739				456,458
Total		$	1,605,000		$	682,091			$	1,043,338
		December 31, 2013
Description		Commitment			Issued and Outstanding				Investments and cash pledged as collateral
$400,000 syndicated unsecured letter of credit facility		$	400,000		$	—			$	—
$525,000 syndicated secured letter of credit facility		525,000			358,567				507,620
$200,000 secured bi-lateral letter of credit facility		200,000			16,726				130,256
Talbot FAL facility		25,000			25,000				30,801
PaCRe senior secured letter of credit facility		10,000			294				—
AlphaCat Re secured letter of credit facility		24,800			24,800				24,806
IPC bi-lateral facility		40,000			20,177				98,465
$375,000 Flagstone bi-lateral facility		375,000			305,686				454,458
Total		$	1,599,800		$	751,250			$	1,246,406
In addition, $3,035,784 of cash and cash equivalents, short-term investments and fixed maturities were pledged during the normal course of business as at September 30, 2014 (December 31, 2013: $2,947,475). Of those, $3,030,932 were held in trust (December 31, 2013: $2,942,508). Pledged assets are generally for the benefit of the Company's cedants and policyholders, to support AlphaCat's fully collateralized reinsurance transactions and to facilitate the accreditation of Talbot as an alien insurer/reinsurer by certain regulators.

Fair_value_measurements

Fair value measurements	9 Months Ended
	Sep. 30, 2014
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 inputs that are unobservable and significant to the overall fair value measurement. The unobservable inputs 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 our 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.
	There have been no material changes in the Company's valuation techniques during the period, or periods, represented by 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.
	At September 30, 2014, the Company’s investments were allocated between Levels 1, 2 and 3 as follows:
		Level 1			Level 2			Level 3			Total
	U.S. government and government agency	$	—		$	786,255		$	—		$	786,255
	Non-U.S. government and government agency	—			381,197			—			381,197
	U.S. states, municipalities and political subdivisions	—			74,365			—			74,365
	Agency residential mortgage-backed securities	—			375,227			—			375,227
	Non-agency residential mortgage-backed securities	—			17,199			—			17,199
	U.S. corporate	—			1,168,918			—			1,168,918
	Non-U.S. corporate	—			594,635			—			594,635
	Bank loans	—			483,788			—			483,788
	Catastrophe bonds	—			43,337			5,001			48,338
	Asset-backed securities	—			566,452			—			566,452
	Commercial mortgage-backed securities	—			173,799			—			173,799
	Total fixed maturities	—			4,665,172			5,001			4,670,173
	Total short-term investments (b)	1,671,911			13,071			—			1,684,982
	Other investments
	Fund of hedge funds	—			—			2,043			2,043
	Hedge funds (a)	—			—			567,840			567,840
	Private equity investments	—			—			15,019			15,019
	Investment funds	—			21,310			102,880			124,190
	Mutual funds	—			9,541			—			9,541
	Total other investments	—			30,851			687,782			718,633
	Total investments including noncontrolling interests	$	1,671,911		$	4,709,094		$	692,783		$	7,073,788
	Noncontrolling interest (a)	$	—		$	—		$	(495,365	)	$	(495,365	)
	Redeemable noncontrolling interest (b)	$	(11,637	)	$	—		$	—		$	(11,637	)
	Total investments excluding noncontrolling interests	$	1,660,274		$	4,709,094		$	197,418		$	6,566,786
	(a)	Included in the hedge funds balance are investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.
	(b)	Included in the short-term investments balance are investments held by one AlphaCat ILS fund which is consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
	At December 31, 2013, the Company’s investments were allocated between Levels 1, 2 and 3 as follows:
		Level 1			Level 2			Level 3			Total
	U.S. government and government agency	$	—		$	1,364,679		$	—		$	1,364,679
	Non-U.S. government and government agency	—			459,068			—			459,068
	U.S. states, municipalities and political subdivisions	—			43,120			—			43,120
	Agency residential mortgage-backed securities	—			311,499			—			311,499
	Non-agency residential mortgage-backed securities	—			15,759			—			15,759
	U.S. corporate	—			1,332,484			—			1,332,484
	Non-U.S. corporate	—			714,325			—			714,325
	Bank loans	—			717,116			—			717,116
	Catastrophe bonds	—			74,551			—			74,551
	Asset-backed securities	—			509,657			—			509,657
	Total fixed maturities	—			5,542,258			—			5,542,258
	Total short-term investments (b)	747,215			4,563			—			751,778
	Other investments
	Fund of hedge funds	—			—			2,303			2,303
	Hedge funds (a)	—			—			561,083			561,083
	Private equity investments	—			—			13,485			13,485
	Investment fund	—			31,629			—			31,629
	Mutual funds	—			9,816			—			9,816
	Total other investments	—			41,445			576,871			618,316
	Total investments including noncontrolling interests	$	747,215		$	5,588,266		$	576,871		$	6,912,352
	Noncontrolling interest (a)	$	—		$	—		$	(489,402	)	$	(489,402	)
	Redeemable noncontrolling interest (b)	$	(18,365	)	$	—		$	—		$	(18,365	)
	Total investments excluding noncontrolling interests	$	728,850		$	5,588,266		$	87,469		$	6,404,585
(a)	Included in the hedge funds balance are investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.
(b)	Included in the short-term investments balance are investments held by two AlphaCat ILS funds which are consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
At September 30, 2014, Level 3 investments excluding the noncontrolling interests totaled $197,418 (December 31, 2013: $87,469), representing 3.0% (December 31, 2013: 1.4%) of total investments, excluding noncontrolling interests, measured at fair value on a recurring basis.
(b)	Level 1 assets measured at fair value
Short term investments
Short term investments categorized as Level 1 consist primarily of highly liquid securities, all with maturities less than one year from the date of purchase. The fair value of the Company's portfolio of short term investments are generally determined using amortized cost which approximates fair value. The Company has determined that certain of its short-term investments, held in highly liquid money market-type funds, should be included in Level 1 as their fair values are based on quoted market prices in active markets.
(c)	Level 2 assets measured at fair value
Fixed maturity investments
Fixed maturity investments included in Level 2 include U.S. government and government agency, non-U.S. government and government agency, U.S. states, municipalities and political subdivisions, agency residential mortgage-backed securities, non-agency residential mortgage-backed securities, U.S. corporate, non-U.S. corporate, bank loans, catastrophe bonds, asset-backed securities and commercial mortgage-backed securities.
In general, valuation of the Company's fixed maturity investment portfolios 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. Securities which are priced by an index provider are generally included in the index.
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 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.
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 who 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.
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.
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 ("TBA") 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.
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 has no fixed maturity investments classified as sub-prime held 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.
U.S. corporate
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.
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.
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.
Catastrophe bonds
Catastrophe bonds are based on broker or underwriter bid indications. To the extent that these indications are based on significant unobservable inputs, the relevant bonds will be classified as a Level 3 asset.
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 value of the securities held in this sector.
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.
Short term investments
Short term investments consist primarily of highly liquid securities, all with maturities less than one year from the date of purchase. The fair value of the Company's portfolio of short term investments is generally determined using amortized cost which approximates fair value. The Company has determined that, other than highly liquid money market-type funds, the remaining securities are classified within Level 2 because these securities are typically not actively traded due to their approaching maturity and, as such, their amortized cost approximates fair value.
Investment funds
Investment funds classified as Level 2 assets consists of one pooled investment which is invested in fixed income securities with high credit ratings. The investment fund is only open to Lloyd’ Trust Fund participants. The fair value of units in the investment fund is based on the net asset value of the fund as reported by Lloyd’s Treasury & Investment Management.
Mutual funds
Mutual funds consist of two investment funds which are invested in various quoted investments. The fair value of units in the mutual funds is based on the net asset value of the fund as reported by the fund manager.
(d)	Level 3 assets measured at fair value
Level 3 includes financial instruments that are valued using market approach and income approach valuation techniques. These models incorporate both observable and unobservable inputs. The Company's hedge funds, a fund of hedge funds, private equity investments, an investment fund and certain catastrophe bonds are the only financial instruments in this category as at September 30, 2014. For each respective hedge fund investment, the Company obtains and reviews the valuation methodology used by the fund administrators and investment managers to ensure that the hedge fund investments are following fair value principles consistent with U.S. GAAP in determining the net asset value (“NAV”).
Within the hedge fund industry, there is a general lack of transparency necessary to facilitate a detailed independent assessment of the values placed on the securities underlying the NAV provided by the fund manager or fund administrator. To address this, on a quarterly basis, we perform a number of monitoring procedures designed to assist in the assessment of the quality of the information provided by managers and administrators. These procedures include, but are not limited to, regular review and discussion of each fund's performance with its manager and regular evaluation of fund performance against applicable benchmarks.
Fund of hedge funds
The fund of hedge funds includes a side pocket. While a redemption request has been submitted, the timing of receipt of proceeds on the side pocket is unknown. The fund's administrator provides a monthly reported NAV with a one-month delay in its valuation. As a result, the fund administrator's August 31, 2014 NAV was used as a basis for fair value measurement in the Company's September 30, 2014 Consolidated Balance Sheet. The fund manager has provided an estimate of the fund NAV at September 30, 2014 based on the estimated performance provided from the underlying funds. To determine the reasonableness of the estimated NAV, the Company compares the one-month delayed fund administrator's NAV to the fund manager's estimated NAV that incorporates relevant valuation sources on a timely basis. Material variances are recorded in the current reporting period while immaterial variances are recorded in the following reporting period. As this valuation technique incorporates both observable and significant unobservable inputs, the fund of hedge funds is classified as a Level 3 asset.
Hedge funds
The hedge funds were valued at $567,840 at September 30, 2014 (December 31, 2013: $561,083). The hedge funds consist of investments in five Paulson & Co. managed funds (the "Paulson hedge funds") and one hedge fund assumed in the acquisition of Flagstone Reinsurance Holdings, S.A. (the "Flagstone Acquisition") (the "Flagstone hedge fund").
The Paulson hedge funds' administrator provides monthly reported NAVs with a one-month delay in its valuation. As a result, the funds' administrator's August 31, 2014 NAV was used as a partial basis for fair value measurement in the Company's September 30, 2014 Consolidated Balance Sheet. The fund manager provides an estimate of the NAV at September 30, 2014 based on estimated performance. The Company adjusts fair value to the fund manager's estimated NAV that incorporates relevant valuation sources on a timely basis. To determine the reasonableness of the estimated NAV, the Company assesses the variance between the fund manager's estimated NAV and the fund administrator's NAV. Material variances are recorded in the current reporting period while immaterial variances are recorded in the following reporting period. Historically, the Company's valuation estimates have not materially differed from the subsequent NAVs.
The Flagstone hedge fund's administrator provides quarterly NAVs with a three-month delay in valuation. As a result, the June 30, 2014 NAV was used as a basis for fair value measurement in the Company's September 30, 2014 Consolidated Balance Sheet.
As these valuation techniques incorporate both observable and significant unobservable inputs, both the Paulson hedge funds and the Flagstone hedge fund are classified as Level 3 assets. The Paulson hedge funds are subject to quarterly liquidity.
Private equity investments
Private equity investments consist of investments in five private equity funds. The private equity funds' respective fund administrators provide quarterly or semi-annual NAVs with a three-month or six-month delay in valuation as well as audited NAVs as at December 31. As a result, the June 30, 2014 or March 31, 2014 NAV was used as a basis for fair value measurement in the Company's September 30, 2014 Consolidated Balance Sheet. As this valuation technique incorporates both observable and significant unobservable inputs, the private equity investments are classified as Level 3 assets.
Investment funds
Investment funds classified as Level 3 assets consists of one structured securities fund that invests across asset backed securities, residential mortgage backed securities and commercial mortgage backed securities. The fair value of units in the investment fund is based on the NAV of the fund as reported by the independent fund administrator. The fund's administrator provides a monthly reported NAV with a one-month delay in its valuation. As a result, the fund administrator's August 31, 2014 NAV was used as a basis for fair value measurement in the Company's September 30, 2014 Consolidated Balance Sheet. As this valuation technique incorporates both observable and significant unobservable inputs, the investment fund investment is classified as a Level 3 asset.
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 nine months ended September 30, 2014 and 2013:
	Three Months Ended						Nine Months Ended
	30-Sep-14			30-Sep-13			30-Sep-14			30-Sep-13
Level 3 investments - Beginning of period	$	746,396		$	505,158		$	576,871		$	556,234
Purchases	25,784			33,154			125,784			98,669
Sales	(24,175		)	(35,264		)	(49,508		)	(80,095		)
Settlements	—			—			(1,500		)	—
Net realized gains	2,554			4,503			8,198			4,843
Change in net unrealized gains (losses)	(57,776		)	42,917			26,235			(29,183		)
Transfers into Level 3	—			—			6,703			—
Level 3 investments - End of period	$	692,783		$	550,468		$	692,783		$	550,468
Noncontrolling interest (a)	(495,365		)	(465,472		)	(495,365		)	(465,472		)
Level 3 investments excluding noncontrolling interest	$	197,418		$	84,996		$	197,418		$	84,996
(a)	Includes Level 3 investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.
There have not been any transfers into or out of Levels 1, 2 and 3 during the three months ended September 30, 2014 or 2013. During the nine months ended September 30, 2014 there was a transfer of investments from Level 2 into Level 3 of the fair value hierarchy. This transfer was due to a reassessment of the extent of unobservable inputs used in establishing the fair value of certain catastrophe bonds. There were no transfers into or out of Level 3 during the nine months ended September 30, 2013.

Investments_in_affiliates

Investments in affiliates	9 Months Ended
	Sep. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
Investments in affiliates	'
	Investments in affiliates
	The following table presents the Company's investments in affiliates as at September 30, 2014 and December 31, 2013:
		30-Sep-14			31-Dec-13
	Investment affiliate	$	42,381		$	34,500
	Operating affiliates	175,231			106,743
	Investments in affiliates	$	217,612		$	141,243
	(a)	Investment affiliate
	Aquiline Financial Services Fund II L.P.
	On December 20, 2011, the Company entered into an Assignment and Assumption Agreement (the "Agreement") with Aquiline Capital Partners LLC, a Delaware limited liability company (the "Assignor") and Aquiline Capital Partners II GP (Offshore) Ltd., a Cayman Islands company limited by shares (the "General Partner") pursuant to which the Company has assumed 100% of the Assignor's interest in Aquiline Financial Services Fund II L.P. (the "Partnership") representing a total capital commitment of $50,000 (the "Commitment"), as a limited partner in the Partnership (the "Transferred Interest"). The Transferred Interest is governed by the terms of an Amended and Restated Exempted Limited Partnership Agreement dated as of July 2, 2010 (the "Limited Partnership Agreement"). Pursuant to the terms of the Limited Partnership Agreement, the Commitment will expire on July 2, 2015.
	The Partnership provides quarterly capital account statements with a three-month delay in its valuation. As a result, the Partnership's June 30, 2014 capital account statement was used as the basis for calculating the Company's share of Partnership income for the period.
	The following table presents a reconciliation of the beginning and ending investment in the Company's investment affiliate balance for the three and nine months ended September 30, 2014 and 2013:
		Three Months Ended							Nine Months Ended
		September 30,			September 30,				September 30,				September 30,
		2014			2013				2014				2013
	Investment affiliate, beginning of period	$	40,627		$	25,352			$	34,500			$	15,218
	Capital contributions	—			6,185				—				13,089
	Income from investment affiliate	1,754			1,044				7,881				4,274
	Investment affiliate, end of period	$	42,381		$	32,581			$	42,381			$	32,581
	The following table presents the Company's investment in the Partnership as at September 30, 2014:
		Investment in investment affiliate
		Investment at cost			Voting ownership %			Equity Ownership			Carrying Value
	Aquiline Financial Services Fund II L.P.	$	32,110		—	%		6.7	%		$	42,381
	The following table presents the Company's investment in the Partnership as at December 31, 2013:
		Investment in investment affiliate
		Investment at cost			Voting ownership %			Equity Ownership			Carrying Value
	Aquiline Financial Services Fund II L.P.	$	32,110		—	%		6.7	%		$	34,500
	(b)	Operating affiliates
	AlphaCat Re 2011 Ltd.
	On May 25, 2011, the Company joined with other investors in capitalizing AlphaCat Re 2011 Ltd. ("AlphaCat Re 2011"), a special purpose reinsurer formed for the purpose of writing collateralized reinsurance and retrocessional reinsurance. AlphaCat Re 2011 was a market facing entity and the Company's investment in AlphaCat Re 2011 has been treated as an equity method investment.
	AlphaCat Re 2011 is now considered "off-risk" as the risk periods for all reinsurance contracts written have expired. As a result, partial returns of investment have been made to the investors of AlphaCat Re 2011.The Company's portion of the returns made during the three and nine months ended September 30, 2014 and 2013 are included in the tables below.
	AlphaCat Re 2012 Ltd.
	On May 29, 2012, the Company joined with other investors in capitalizing AlphaCat Re 2012 Ltd. ("AlphaCat Re 2012"), a special purpose reinsurer formed for the purpose of writing collateralized reinsurance with a particular focus on windstorm risks for Florida domiciled insurance companies. AlphaCat Re 2012 was a market facing entity and the Company's investment in AlphaCat Re 2012 has been treated as an equity method investment.
	AlphaCat Re 2012 is now considered "off-risk" as the risk periods for all reinsurance contracts written have expired. As a result, partial returns of investment have been made to the investors of AlphaCat Re 2012.The Company's portion of the returns made during the three and nine months ended September 30, 2014 and 2013 are included in the tables below.
	AlphaCat 2013, Ltd.
	On December 17, 2012, the Company joined with other investors in capitalizing AlphaCat 2013, Ltd. ("AlphaCat 2013"), an entity formed for the purpose of investing in collateralized reinsurance and retrocession on a worldwide basis. AlphaCat 2013 deployed its capital through transactions entered into by AlphaCat Reinsurance Ltd. (“AlphaCat Re”) and the Company's investment in AlphaCat 2013 has been treated as an equity method investment.
	AlphaCat 2013 is now considered "off-risk" as the risk periods for all risk-linked instruments have expired. As a result, partial returns of investment have been made to the investors of AlphaCat 2013. The Company's portion of the returns made during the three and nine months ended September 30, 2014 and 2013 are included in the tables below.
	AlphaCat 2014, Ltd.
	On December 20, 2013, the Company joined with other investors in capitalizing AlphaCat 2014, Ltd. (“AlphaCat 2014”), an entity formed for the purpose of investing in collateralized reinsurance and retrocessional contracts for the January 1, 2014 renewal season. AlphaCat 2014 deploys its capital through transactions entered into by AlphaCat Re and the Company's investment in AlphaCat 2014 has been treated as an equity method investment.
	AlphaCat ILS funds
	The AlphaCat ILS funds invest in instruments with returns linked to property catastrophe reinsurance, retrocession and insurance linked securities ("ILS") contracts. AlphaCat ILS funds all deploy their capital through the AlphaCat Master Fund Ltd. (the “Master Fund”) and AlphaCat Re. All three funds are variable interest entities, with one being consolidated by the Company as the primary beneficiary and one being accounted for as an equity method investment because the Company holds an equity interest of 7.9% and has significant influence. The third fund had been consolidated by the Company as the primary beneficiary from its formation through to December 31, 2013. However, on January 1, 2014 the fund received $35,000 in additional third party subscriptions, resulting in a reduction of the Company’s equity interest below 50%. Since the Company retains significant influence, this fund has been deconsolidated and accounted for as an equity method investment from January 1, 2014. The fair value of the retained interest, based on the fair value of the underlying instruments in Master Fund and AlphaCat Re, amounted to $113,455 at January 1, 2014. The deconsolidation resulted in a gain of $1,372 which is included in the Consolidated Statements of Comprehensive Income as other income for the nine months ended September 30, 2014. The Company's maximum exposure to any of the funds is the amount of capital invested at any given time.
	AlphaCat Master Fund Ltd. and AlphaCat Reinsurance Ltd.
	The Company utilizes Master Fund and AlphaCat Re for the purpose of investing in capital market products and writing collateralized reinsurance, respectively, on behalf of certain entities within the AlphaCat operating segment. Master Fund and AlphaCat Re are market facing entities which enter into transactions on behalf of AlphaCat 2013, AlphaCat 2014 and the AlphaCat ILS funds. The Company owns all of the voting equity interest in Master Fund and AlphaCat Re and, as a result, their financial statements are included in the Consolidated Financial Statements of the Company.
	The following tables present a reconciliation of the beginning and ending investment in operating affiliates for the three and nine months ended September 30, 2014 and 2013:
		Three Months Ended September 30, 2014
		AlphaCat Re 2011			AlphaCat Re 2012				AlphaCat 2013				AlphaCat 2014			AlphaCat ILS funds			Total
	As at June 30, 2014	$	4,172		$	2,204			$	2,580			$	25,014		$	139,022		$	172,992
	Return of investment	—			(1,516		)		(6		)		—			—			(1,522		)
	(Loss) income from operating affiliates	(5		)	(9		)		7				1,367			2,401			3,761
	As at September 30, 2014	$	4,167		$	679			$	2,581			$	26,381		$	141,423		$	175,231
		Three Months Ended September 30, 2013
		AlphaCat Re 2011			AlphaCat Re 2012				AlphaCat 2013				AlphaCat ILS fund			Total
	As at June 30, 2013	$	11,054		$	5,204			$	48,536			$	20,326		$	85,120
	Return of investment	(2,800		)	(4,550		)		—				—			(7,350		)
	(Loss) income from operating affiliates	(270		)	(7		)		585				1,155			1,463
	As at September 30, 2013	$	7,984		$	647			$	49,121			$	21,481		$	79,233
		Nine Months Ended September 30, 2014
		AlphaCat Re 2011			AlphaCat Re 2012				AlphaCat 2013				AlphaCat 2014			AlphaCat ILS funds			Total
	As at December 31, 2013	$	9,809		$	1,313			$	51,744			$	21,982		$	21,895		$	106,743
	Return of investment	(5,825		)	(1,516		)		(51,206		)		—			—			(58,547		)
	Fair value of retained interest on deconsolidation of AlphaCat ILS fund	—			—				—				—			113,455			113,455
	Income from operating affiliates	183			882				2,043				4,399			6,073			13,580
	As at September 30, 2014	$	4,167		$	679			$	2,581			$	26,381		$	141,423		$	175,231
		Nine Months Ended September 30, 2013
	AlphaCat Re 2011			AlphaCat Re 2012				AlphaCat 2013				AlphaCat ILS fund			Total
As at December 31, 2012	$	62,792		$	29,319			$	45,000			$	20,000		$	157,111
Return of investment	(54,914		)	(31,743		)		—				—			(86,657		)
Income from operating affiliates	106			3,071				4,121				1,481			8,779
As at September 30, 2013	$	7,984		$	647			$	49,121			$	21,481		$	79,233
The following table presents the Company's investments in AlphaCat Re 2011, AlphaCat Re 2012, AlphaCat 2013, AlphaCat 2014 and the AlphaCat ILS funds in the Consolidated Financial Statements as at September 30, 2014:
	Investment in operating affiliates
	Cost			Voting ownership %			Equity ownership %			Carrying value
AlphaCat Re 2011	$	4,167		43.7	%		22.3	%		$	4,167
AlphaCat Re 2012	679			49	%		37.9	%		679
AlphaCat 2013	2,581			40.9	%		19.7	%		2,581
AlphaCat 2014	22,000			42.3	%		19.6	%		26,381
AlphaCat ILS funds	133,455			n/a			(a)			141,423
Total	$	162,882								$	175,231
(a)	Equity ownership in the two funds were 7.9% and 49.0% respectively as at September 30, 2014.
The following table presents the Company's investments in AlphaCat Re 2011, AlphaCat Re 2012, AlphaCat 2013, AlphaCat 2014 and the AlphaCat ILS fund in the Consolidated Financial Statements as at December 31, 2013:
	Investment in operating affiliates
	Cost			Voting ownership %			Equity ownership %			Carrying value
AlphaCat Re 2011	$	9,882		43.7	%		22.3	%		$	9,809
AlphaCat Re 2012	654			49	%		37.9	%		1,313
AlphaCat 2013	45,000			40.9	%		19.7	%		51,744
AlphaCat 2014	22,000			42.3	%		19.6	%		21,982
AlphaCat ILS fund	20,000			n/a			9.1	%		21,895
Total	$	97,536								$	106,743
(c)	Notes payable and (income) attributable to operating affiliates
Notes are issued during the course of a year by Master Fund and AlphaCat Re to AlphaCat 2013, AlphaCat 2014 and the AlphaCat ILS funds (collectively the “feeder funds”) in order to fund the purchase of capital market products and to write collateralized reinsurance on their behalf. The underlying capital market products and collateralized reinsurance typically have at least a twelve month duration; however, they do not have a stated maturity date. Since repayment is dependent on the settlement of the underlying transactions, the notes are subsequently redeemed as the underlying transactions are settled. The Company’s investments in the feeder funds, together with investments made by third parties, are provided as consideration for these notes to Master Fund and AlphaCat Re, which are consolidated in the Company’s Consolidated Financial Statements. The effective economic interest in Master Fund and AlphaCat Re that results from these transactions is represented on the Consolidated Balance Sheet as notes payable to operating affiliates. The subsequent income or loss generated by the relevant capital market products or collateralized reinsurance is transferred to the operating affiliates as (income) loss attributable to operating affiliate investors in the Company’s Consolidated Statements of Comprehensive Income. The notes do not have any principal amount, since the final amount payable is dependent on the income or loss. To the extent that the (income) loss attributable to operating affiliate investors has not been returned to investors, it is included in accounts payable and accrued expenses in the Consolidated Balance Sheets.
The following tables present a reconciliation of the beginning and ending notes payable to operating affiliates for the three and nine months ended September 30, 2014 and 2013:
	Three Months Ended September 30, 2014
	AlphaCat 2013			AlphaCat 2014				AlphaCat ILS funds				Total
As at June 30, 2014	$	—		$	157,992			$	464,958			$	622,950
Issuance of notes payable to operating affiliates	—			—				53,498				53,498
Redemption of notes payable to operating affiliates	—			—				(13,990		)		(13,990		)
Foreign exchange gain	—			(410		)		(6,072		)		(6,482		)
As at September 30, 2014	$	—		$	157,582			$	498,394			$	655,976
	Three Months Ended September 30, 2013
	AlphaCat 2013			AlphaCat ILS funds				Total
As at June 30, 2013	$	222,135		$	208,958			$	431,093
Issuance of notes payable to operating affiliates	—			6,733				6,733
Redemption of notes payable to operating affiliates	—			(3,553		)		(3,553		)
Foreign exchange loss	1,196			2,501				3,697
As at September 30, 2013	$	223,331		$	214,639			$	437,970
	Nine Months Ended September 30, 2014
	AlphaCat 2013			AlphaCat 2014				AlphaCat ILS funds				Total
As at December 31, 2013	$	223,809		$	—			$	215,463			$	439,272
Notes payable to operating affiliates recognized on deconsolidation of AlphaCat ILS fund	—			—				178,837				178,837
Issuance of notes payable to operating affiliates	—			157,914				487,329				645,243
Redemption of notes payable to operating affiliates	(223,512		)	—				(378,556		)		(602,068		)
Foreign exchange gain	(297		)	(332		)		(4,679		)		(5,308		)
As at September 30, 2014	$	—		$	157,582			$	498,394			$	655,976
	Nine Months Ended September 30, 2013
	AlphaCat 2013			AlphaCat ILS funds				Total
As at December 31, 2012	$	—		$	—			$	—
Issuance of notes payable to operating affiliates	223,082			218,044				441,126
Redemption of notes payable to operating affiliates	—			(3,553		)		(3,553		)
Foreign exchange loss	249			148				397
As at September 30, 2013	$	223,331		$	214,639			$	437,970
The portion of notes payable to operating affiliates that were due to the Company, as an investor in the affiliates, and third party investors as at September 30, 2014 amounted to $164,169 and $491,807, respectively (December 31, 2013: $63,654 and $375,618).
The following table presents the (income) attributable to operating affiliate investors for the three and nine months ended September 30, 2014 and 2013:
	Three Months Ended							Nine Months Ended
	September 30,			September 30,				September 30,				September 30,
	2014			2013				2014				2013
AlphaCat 2013	$	(98	)	$	(4,074	)		$	(14,218	)		$	(29,357	)
AlphaCat 2014	(11,309		)	—				(32,990		)		—
AlphaCat ILS funds	(14,400		)	(7,741		)		(35,625		)		(12,799		)
(Income) attributable to operating affiliate investors	$	(25,807	)	$	(11,815	)		$	(82,833	)		$	(42,156	)
The portion of income attributable to operating affiliate investors that was due to the Company, as an investor in the affiliates, and third party investors for the three months ended September 30, 2014 amounted to $4,993 and $20,814, respectively (2013: $1,505 and $10,310). The portion of income attributable to operating affiliate investors that was due to the Company, as an investor in the affiliates, and third party investors for the nine months ended September 30, 2014 amounted to $16,552 and $66,281, respectively (2013: $7,114 and $35,042).

Noncontrolling_interest

Noncontrolling interest	9 Months Ended
	Sep. 30, 2014
Noncontrolling Interest [Abstract]	'
Noncontrolling interest	'
	Noncontrolling interest
	On April 2, 2012, the Company joined with other investors in capitalizing PaCRe Ltd. ("PaCRe"), a Class 4 Bermuda reinsurer formed for the purpose of writing high excess property catastrophe reinsurance. The Company has an equity interest of 10% and the remaining 90% interest is held by third party investors. The Company has a majority voting equity interest in PaCRe and as a result, the financial statements of PaCRe are included in the Consolidated Financial Statements of the Company. The portion of PaCRe’s earnings attributable to third party investors is recorded in the Consolidated Statements of Comprehensive Income as net (income) loss attributable to noncontrolling interest. PaCRe's shareholder rights do not include redemption features within the control of the third party shareholders. The third party equity is recorded in the Company’s Consolidated Balance Sheets as noncontrolling interest.
	The portion of earnings from the one consolidated AlphaCat ILS fund attributable to third party investors is recorded in the Consolidated Statements of Comprehensive Income as net (income) loss attributable to noncontrolling interest. The AlphaCat ILS funds have rights that enable shareholders, subject to certain limitations, to redeem their shares. The third party equity is therefore recorded in the Company’s Consolidated Balance Sheets as redeemable noncontrolling interest. When and if a redemption notice is received, the fair value of the redemption is reclassified to a liability.
	The following tables present a reconciliation of the beginning and ending balances of redeemable noncontrolling interest and noncontrolling interest for the three and nine months ended September 30, 2014 and 2013:
		Three Months Ended September 30, 2014
		Redeemable noncontrolling interest			Noncontrolling interest			Total
	As at June 30, 2014	$	66,282		$	575,347		$	641,629
	Issuance of shares	4,200			—			4,200
	Loss attributable to noncontrolling interest	(9		)	(53,060		)	(53,069		)
	As at September 30, 2014	$	70,473		$	522,287		$	592,760
		Three Months Ended September 30, 2013
		Redeemable noncontrolling interest			Noncontrolling interest			Total
	As at June 30, 2013	$	70,690		$	427,755		$	498,445
	Issuance of shares	13,000			—			13,000
	Income attributable to noncontrolling interest	1,516			44,178			45,694
	Redemption of shares	(10,207		)	—			(10,207		)
	As at September 30, 2013	$	74,999		$	471,933		$	546,932
		Nine Months Ended September 30, 2014
		Redeemable noncontrolling interest			Noncontrolling interest			Total
	As at December 31, 2013	$	86,512		$	497,657		$	584,169
	Issuance of shares	61,200			—			61,200
	Income attributable to noncontrolling interest	1,115			24,630			25,745
	Adjustment to noncontrolling interest as a result of deconsolidation	(78,354		)	—			(78,354		)
	As at September 30, 2014	$	70,473		$	522,287		$	592,760
		Nine Months Ended September 30, 2013
		Redeemable noncontrolling interest			Noncontrolling interest			Total
	As at December 31, 2012	$	—		$	434,280		$	434,280
	Issuance of shares	82,190			58,500			140,690
	Income (loss) attributable to noncontrolling interest	3,016			(20,847		)	(17,831		)
	Redemption of shares	(10,207		)	—			(10,207		)
	As at September 30, 2013	$	74,999		$	471,933		$	546,932

Derivative_instruments

Derivative instruments	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative instruments	'
	Derivative instruments
	The Company enters into derivative instruments for risk management purposes, specifically to hedge unmatched foreign currency exposures and interest rate exposures. As at September 30, 2014, the Company held foreign currency forward contracts to mitigate the risk of fluctuations in the U.S. dollar against a number of foreign currencies. As at September 30, 2014, the Company held two interest rate swaps to fix the payment of interest on the Company's 2006 and 2007 Junior Subordinated Deferrable Debentures, as well as three interest rate swaps and one cross-currency interest rate swap to fix the payment of interest and mitigate the foreign exchange rate impact on Flagstone's 2006 and 2007 Junior Subordinated Deferrable Debentures.
	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 at September 30, 2014 and December 31, 2013:
			As at September 30, 2014									As at December 31, 2013
	Derivatives designated as hedging instruments:		Net Notional Exposure			Asset Derivative at Fair Value (a)			Liability Derivative at Fair Value (a)			Net Notional Exposure			Asset Derivative at Fair Value (a)		Liability Derivative at Fair Value (a)
	Foreign currency forward contracts		$	246,638		$	592		$	16,672		$	163,576		$	1,167	$	2,313
	Interest rate swap contracts		$	552,263		$	25		$	912		$	552,263		$	28	$	911
	(a)	Asset and liability derivatives are classified within other assets and accounts payable and accrued expenses respectively on the Consolidated Balance Sheets.
	(a)	Classification within the fair value hierarchy
	As described in Note 4: "Fair value measurements" under U.S. GAAP, a company must determine the appropriate level in the fair value hierarchy for each fair value measurement. The assumptions used within the valuation of the Company's derivative instruments are observable in the marketplace, can be derived from observable data or are supported by observable levels at which other similar transactions are executed in the marketplace. Accordingly, these derivatives were classified within Level 2 of the fair value hierarchy.
	(b)	Derivative instruments designated as a fair value hedge
	The Company designates its foreign currency derivative instruments as fair value hedges and formally and contemporaneously documents all relationships between the derivative instruments and hedged items and links the derivative instruments to specific assets and liabilities. The Company assesses the effectiveness of the hedges, both at inception and on an on-going basis and determines whether the hedges are highly effective in offsetting changes in fair value of the linked hedged items.
	The following table provides the total impact on earnings, recognized in income within foreign exchange gains (losses), relating to the derivative instruments formally designated as fair value hedges along with the impact of the related hedged items for the three and nine months ended September 30, 2014 and 2013:
			Three Months Ended						Nine Months Ended
	Foreign currency forward contracts		September 30, 2014			September 30, 2013			September 30, 2014			September 30, 2013
	Amount of (loss) gain recognized in income on derivative		$	(14,817	)	$	3,116		$	(9,979	)	$	2,670
	Amount of gain (loss) on hedged item recognized in income attributable to risk being hedged		$	14,817		$	(3,116	)	$	9,979		$	(2,670	)
	Amount of gain (loss) recognized in income on derivative (ineffective portion)		$	—		$	—		$	—		$	—
	(c)	Derivative instruments designated as a cash flow hedge
	The Company designates its interest rate derivative instruments as cash flow hedges and formally and contemporaneously documents all relationships between the hedging instruments and hedged items and links the derivative instruments to specific assets and liabilities. The Company assesses the effectiveness of the hedges, both at inception and on an on-going basis and determines whether the hedges are highly effective in offsetting changes in fair value of the linked hedged items. The Company currently applies the long haul method when assessing the hedge's effectiveness.
	The following table provides the total impact on other comprehensive income (loss) and earnings relating to the derivative instruments formally designated as cash flow hedges along with the impact of the related hedged items for the three and nine months ended September 30, 2014 and 2013:
			Three Months Ended						Nine Months Ended
	Interest rate swap contracts		September 30, 2014			September 30, 2013			September 30, 2014			September 30, 2013
	Amount of effective portion recognized in other comprehensive income		$	3,302		$	3,268		$	9,762		$	7,838
	Amount of effective portion subsequently reclassified to earnings		$	(3,302	)	$	(3,268	)	$	(9,762	)	$	(7,838	)
	Amount of ineffective portion excluded from effectiveness testing		$	—		$	—		$	—		$	—
	The above balances relate to interest payments and have therefore been classified as finance expenses in the Consolidated Statements of Comprehensive Income.
	(d)	Balance sheet offsetting
	There was no balance sheet offsetting activity as at September 30, 2014 or December 31, 2013.
	The Company currently provides cash collateral as security for interest rate swap contracts. The Company does not provide cash collateral or financial instruments as security for foreign currency forward contracts. Our derivative instruments are generally traded under International Swaps and Derivatives Association master netting 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_ex

Reserve for losses and loss expenses	9 Months Ended
	Sep. 30, 2014
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
	Reserves for losses and loss expenses are based in part upon the estimation of case reserves from broker, insured and ceding company reported data. The Company also uses statistical and actuarial methods to estimate ultimate expected losses and loss expenses, from which incurred but not reported losses can be calculated. The period of time from the occurrence of a loss to the reporting of a loss to the Company and to the settlement of the Company's liability may be several months or years. During this period, additional facts and trends may be revealed. As these factors become apparent, reserves will be adjusted, sometimes requiring an increase or decrease in the overall reserves of the Company, and at other times requiring a reallocation of incurred but not reported reserves to specific case reserves. These estimates are reviewed and adjusted regularly, and such adjustments, if any, are reflected in earnings in the period in which they become known. While management believes that it has made a reasonable estimate of ultimate losses, there can be no assurances that ultimate losses and loss expenses will not exceed this estimate.
	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 nine months ended September 30, 2014 and 2013:
		Three Months Ended						Nine Months Ended
		September 30,			September 30,			September 30,			September 30,
		2014			2013			2014			2013
	Reserve for losses and loss expenses, beginning of period	$	2,867,307		$	3,283,450		$	3,030,399		$	3,517,573
	Losses and loss expenses recoverable	(338,734		)	(418,693		)	(370,154		)	(439,967		)
	Net reserves for losses and loss expenses, beginning of period	2,528,573			2,864,757			2,660,245			3,077,606
	Net reserves disposed	—			—			—			(18,591		)
	Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
	Current year	279,690			243,015			713,177			759,617
	Prior years	(55,565		)	(65,050		)	(167,636		)	(171,837		)
	Total incurred losses and loss expenses	224,125			177,965			545,541			587,780
	Less net losses and loss expenses paid in respect of losses occurring in:
	Current year	(74,618		)	(59,701		)	(99,326		)	(95,535		)
	Prior years	(183,697		)	(215,167		)	(633,048		)	(732,118		)
	Total net paid losses	(258,315		)	(274,868		)	(732,374		)	(827,653		)
	Foreign exchange	(40,717		)	34,363			(19,746		)	(16,925		)
	Net reserve for losses and loss expenses, end of period	2,453,666			2,802,217			2,453,666			2,802,217
	Losses and loss expenses recoverable	298,502			421,518			298,502			421,518
	Reserve for losses and loss expenses, end of period	$	2,752,168		$	3,223,735		$	2,752,168		$	3,223,735
	Incurred losses and loss expenses comprise:
		Three Months Ended						Nine Months Ended
		September 30,			September 30,			September 30,			September 30,
		2014			2013			2014			2013
	Gross losses and loss expenses	$	222,356		$	226,130		$	587,111		$	684,080
	Reinsurance recoverable	1,769			(48,165		)	(41,570		)	(96,300		)
	Net incurred losses and loss expenses	$	224,125		$	177,965		$	545,541		$	587,780

Reinsurance

Reinsurance	9 Months Ended
	Sep. 30, 2014
Reinsurance Disclosures [Abstract]	'
Reinsurance	'
	Reinsurance
	The Company enters into reinsurance and retrocession agreements in order to mitigate its accumulation of loss, reduce its liability on individual risks, enable it to underwrite policies with higher limits and increase its aggregate capacity. The cession of insurance and reinsurance does not legally discharge the Company from its primary liability for the full amount of the policies, and the Company is required to pay the loss and bear collection risk if the reinsurer fails to meet its obligations under the reinsurance or retrocession agreement. Amounts recoverable from reinsurers are estimated in a manner consistent with the underlying liabilities.
	Credit risk
	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, was 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. At September 30, 2014, 97.3% (December 31, 2013: 96.7%) of reinsurance recoverables (which includes loss reserves recoverable and recoverables on paid losses and $144,414 of total IBNR recoverable (December 31, 2013: $196,840)) were fully collateralized or from reinsurers rated A- or better.
	Reinsurance recoverables by reinsurer as at September 30, 2014 and December 31, 2013 are as follows:
		September 30, 2014					December 31, 2013
		Reinsurance Recoverable			% of Total		Reinsurance Recoverable		% of Total
	Top 10 reinsurers	$	264,131		73.1	%	$	340,253	75.6	%
	Other reinsurers’ balances > $1 million	89,584			24.8	%	100,784		22.4	%
	Other reinsurers’ balances < $1 million	7,778			2.1	%	9,197		2	%
	Total	$	361,493		100	%	$	450,234	100	%
			September 30, 2014
	Top 10 Reinsurers		Rating	Reinsurance Recoverable			% of Total
	Lloyd's Syndicates		A+	$	60,218		16.7	%
	Everest Re		A+	46,765			12.9	%
	Third Point Re		A-	34,180			9.5	%
	Fully Collateralized		NR	33,770			9.3	%
	Hannover Re		AA-	33,124			9.2	%
	Swiss Re		AA-	13,849			3.8	%
	Transatlantic Re		A+	11,649			3.2	%
	XL Re		A+	10,334			2.9	%
	Munich Re		AA-	10,232			2.8	%
	Aioi Nissay Dowa Insurance		A+	10,010			2.8	%
	Total			$	264,131		73.1	%
	NR: Not rated
			December 31, 2013
	Top 10 Reinsurers		Rating	Reinsurance Recoverable			% of Total
	Lloyd's Syndicates		A+	$	73,398		16.3	%
	National Indemnity		AA+	51,037			11.3	%
	Everest Re		A+	48,055			10.7	%
	Hannover Re		AA-	41,483			9.2	%
	Fully Collateralized		NR	36,683			8.1	%
	Third Point Re		A-	30,428			6.8	%
	Swiss Re		AA-	20,022			4.5	%
	Transatlantic Re		A+	14,114			3.1	%
	XL Re		A+	12,673			2.8	%
	Munich Re		AA-	12,360			2.8	%
	Total			$	340,253		75.6	%
	NR: Not rated
	At September 30, 2014 and December 31, 2013, the provision for uncollectible reinsurance relating to reinsurance recoverables was $5,380 and $5,794, respectively. To estimate the provision for uncollectible reinsurance, the reinsurance recoverable is first allocated to applicable reinsurers. This determination is based on a process rather than an estimate, although an element of judgment is applied, especially in relation to ceded IBNR. The Company then uses default factors to determine the portion of a reinsurer’s balance deemed to be uncollectible. Default factors require considerable judgment and are determined in part using the current rating, or rating equivalent, of each reinsurer as well as other key considerations and assumptions.

Share_capital

Share capital	9 Months Ended
	Sep. 30, 2014
Stockholders' Equity Note [Abstract]	'
Share capital	'
	Share capital
	(a)	Authorized and issued
	The Company’s authorized share capital is 571,428,571 common shares with a par value of $0.175 per share. The holders of common shares are entitled to receive dividends. Holders of common shares are allocated one vote per share, provided that, if the controlled shares of any shareholder or group of related shareholders constitute more than 9.09 percent of the outstanding common shares of the Company, their voting power will be reduced to 9.09 percent.
	The Company may from time to time repurchase its securities, including common shares, Junior Subordinated Deferrable Debentures and Senior Notes. On February 5, 2014, the Board of Directors of the Company approved an increase in the Company's common share purchase authorization to $500,000. This amount is in addition to the $1,774,436 of common shares repurchased by the Company through February 5, 2014 under its previously authorized share repurchase programs.
	The Company has repurchased 64,502,410 common shares for an aggregate purchase price of $2,006,875 from the inception of its share repurchase program to September 30, 2014. The Company had $267,561 remaining under its authorized share repurchase program as of September 30, 2014.
	The Company expects the purchases under its share repurchase program to be made from time to time in the open market or in privately negotiated transactions. The timing, form and amount of the share repurchases under the program will depend on a variety of factors, including market conditions, the Company’s capital position relative to internal and rating agency targets, legal requirements and other factors. The repurchase program may be modified, extended or terminated by the Board of Directors at any time.
	The following table is a summary of the common shares issued and outstanding:
		Common Shares
	Common shares issued, December 31, 2013	154,488,497
	Restricted share awards vested, net of shares withheld	594,582
	Restricted share units vested, net of shares withheld	10,265
	Options exercised	133,385
	Direct issuance of common stock	1,060
	Performance share awards vested, net of shares withheld	25,767
	Common shares issued, September 30, 2014	155,253,556
	Treasury shares, September 30, 2014	(66,141,285	)
	Common shares outstanding, September 30, 2014	89,112,271
		Common Shares
	Common shares issued, December 31, 2012	152,698,191
	Restricted share awards vested, net of shares withheld	768,889
	Restricted share units vested, net of shares withheld	14,381
	Options exercised	277,615
	Warrants exercised	591,480
	Direct issuance of common stock	928
	Performance share awards vested, net of shares withheld	31,897
	Deferred share units vested, net of shares withheld	2,935
	Common shares issued, September 30, 2013	154,386,316
	Treasury shares, September 30, 2013	(54,488,320	)
	Common shares outstanding, September 30, 2013	99,897,996
	(b)	Warrants
	During the nine months ended September 30, 2014, no warrants were exercised. During the nine months ended September 30, 2013, 1,114,416 warrants were exercised which resulted in the issuance of 591,480 common shares. Holders of the outstanding warrants are entitled to exercise the warrants in whole or in part at any time until the expiration date. The total outstanding warrants at September 30, 2014 were 5,174,114 (December 31, 2013: 5,296,056). No further warrants are anticipated to be issued.
	(c)	Deferred share units
	Under the terms of the Company’s Director Stock Compensation Plan, non-management directors may elect to receive their director fees in deferred share units rather than cash. The number of share units distributed in case of election under the plan is equal to the amount of the annual retainer fee otherwise payable to the director on such payment date divided by 100% of the fair market value of a share on such payment date. Additional deferred share units are issued in lieu of dividends that accrue on these deferred share units.  There were no outstanding deferred share units at September 30, 2014 (December 31, 2013: $nil).
	As of February 16, 2013, John Hendrickson became an employee director. As a result, his 5,039 deferred share units vested and 2,935 common shares were issued to him, net of shares withheld for taxes.
	(d)	Dividends
	On July 29, 2014, the Company announced a quarterly cash dividend of $0.30 (2013: $0.30) per common share and $0.30 per common share equivalent for which each outstanding warrant is exercisable. This dividend was paid on September 30, 2014 to holders of record on September 15, 2014.
	On April 30, 2014, the Company announced a quarterly cash dividend of $0.30 (2013: $0.30) per common share and $0.30 per common share equivalent for which each outstanding warrant is exercisable. This dividend was paid on June 30, 2014 to holders of record on June 13, 2014.
	On February 5, 2014, the Company announced a quarterly cash dividend of $0.30 (2013: $0.30) per common share and $0.30 per common share equivalent for which each outstanding warrant is exercisable. This dividend was paid on March 31, 2014 to holders of record on March 14, 2014.
	On February 6, 2013, the Company announced a special dividend in the amount of $2.00 per common share and $2.00 per common share equivalent for which each outstanding warrant is exercisable (the "2013 Special Dividend"). The 2013 Special Dividend was paid on February 26, 2013 to shareholders and warrant holders of record as of February 19, 2013.

Stock_plans

Stock plans	9 Months Ended
	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stock plans	'
	Stock plans
	(a)	Long Term Incentive Plan and Short Term Incentive Plan
	The Company’s Amended and Restated 2005 Long Term Incentive Plan (“LTIP”) provides for grants to employees of options, stock appreciation rights (“SARs”), restricted shares, restricted share units, performance shares, dividend equivalents or other share-based awards. In addition, the Company may issue restricted share awards or restricted share units in connection with awards issued under its annual Short Term Incentive Plan (“STIP”). The total number of shares reserved for issuance under the LTIP and STIP are 13,126,896 shares of which 1,018,998 shares are remaining. The LTIP and STIP are administered by the Compensation Committee of the Board of Directors. No SARs have been granted to date. Grant prices are established at the fair market value of the Company’s common shares at the date of grant.
	i.	Options
	Options may be exercised for voting common shares upon vesting. Options have a life of 10 years and vest either pro rata or at the end of the required service period from the date of grant. Fair value of the option awards at the date of grant is determined using the Black-Scholes option-pricing model.
	Expected volatility is based on 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 as historical exercise data was not available and the options met the requirement as set out in the guidance.
	The Company has not granted any stock options since September 4, 2009.
	There were no share compensation expenses in respect of options recognized for the three and nine months ended September 30, 2014 and 2013.
	A modification event was triggered as a result of the 2013 Special Dividend. In accordance with the terms of the LTIP under which the options were issued, an adjustment was required to protect the holders of such stock options from changes in the value of the stock options following the declaration of the 2013 Special Dividend. The modification of the options included a decrease in the exercise price of each stock option and an increase in the number of shares underlying each stock option. The fair value of the options before and after the modification was unchanged.
	Activity with respect to options for the nine months ended September 30, 2014 was as follows:
		Options		Weighted Average Grant Date Fair Value			Weighted Average Grant Date Exercise Price
	Options outstanding, December 31, 2013	1,572,713		$	6.66		$	18.88
	Options exercised	(133,385	)	3.81			25.1
	Options outstanding, September 30, 2014	1,439,328		$	6.93		$	18.3
	Activity with respect to options for the nine months ended September 30, 2013 was as follows:
		Options		Weighted Average Grant Date Fair Value			Weighted Average Grant Date Exercise Price
	Options outstanding, December 31, 2012	1,823,947		$	6.52		$	20.69
	Options regranted (modified)	1,833,414		6.76			19.02
	Options exercised	(277,615	)	5.24			23.58
	Options cancelled (modified)	(1,733,139	)	6.76			20.12
	Options outstanding, September 30, 2013	1,646,607		$	6.75		$	18.94
	At September 30, 2014 and 2013, there were no unrecognized share compensation expenses in respect of options.
	ii.	Restricted share awards
	Restricted shares granted under the LTIP and STIP vest either pro rata or 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 during the three and nine months ended September 30, 2014 of $8,180 (2013: $10,041) and $23,101 (2013: $20,035), 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 nine months ended September 30, 2014 was as follows:
		Restricted Share Awards		Weighted Average Grant Date Fair Value
	Restricted share awards outstanding, December 31, 2013	2,684,745		$	33.74
	Restricted share awards granted	925,610		37.33
	Restricted share awards vested	(769,971	)	31.47
	Restricted share awards forfeited	(69,117	)	36.28
	Restricted share awards outstanding, September 30, 2014	2,771,267		$	35.5
	Activity with respect to unvested restricted share awards for the nine months ended September 30, 2013 was as follows:
		Restricted Share Awards		Weighted Average Grant Date Fair Value
	Restricted share awards outstanding, December 31, 2012	2,170,547		$	29.24
	Restricted share awards granted	1,580,117		36.06
	Restricted share awards vested	(930,296	)	28.08
	Restricted share awards forfeited	(110,912	)	28.34
	Restricted share awards outstanding, September 30, 2013	2,709,456		$	33.65
	At September 30, 2014, there were $77,920 (December 31, 2013: $69,219) of total unrecognized share compensation expenses in respect of restricted share awards that are expected to be recognized over a weighted-average period of 3.0 years (December 31, 2013: 3.2 years).
	iii.	Restricted share units
	Restricted share units under the LTIP and STIP vest either ratably or 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 during the three and nine months ended September 30, 2014 of $269 (2013: $168) and $602 (2013: $419), 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 nine months ended September 30, 2014 was as follows:
		Restricted Share Units		Weighted Average Grant Date Fair Value
	Restricted share units outstanding, December 31, 2013	66,518		$	33.74
	Restricted share units granted	53,025		38.1
	Restricted share units vested	(18,325	)	30.71
	Restricted share units issued in lieu of cash dividends	1,479		34.19
	Restricted share units outstanding, September 30, 2014	102,697		$	36.54
	Activity with respect to unvested restricted share units for the nine months ended September 30, 2013 was as follows:
		Restricted Share Units		Weighted Average Grant Date Fair Value
	Restricted share units outstanding, December 31, 2012	47,238		$	29.61
	Restricted share units granted	36,635		36.11
	Restricted share units vested	(21,814	)	28.17
	Restricted share units issued in lieu of cash dividends	3,924		30.29
	Restricted share units outstanding, September 30, 2013	65,983		$	33.74
	At September 30, 2014, there were $3,038 (December 31, 2013: $1,678) of total unrecognized share compensation expenses in respect of restricted share units that are expected to be recognized over a weighted-average period of 3.3 years (December 31, 2013: 3.4 years).
	iv.	Performance share awards
	The performance share awards contain a performance based component. The performance component relates to the compounded growth in the Dividend Adjusted Diluted Book Value per Share (“DBVPS”) over a three year period relative to the Company's peer group. For performance share awards granted during the period, the grant date Diluted Book Value per Share is based on the DBVPS at the end of the most recent financial reporting year. The Dividend Adjusted Performance Period End DBVPS will be the DBVPS three years after the grant date DBVPS. The fair value estimate earns over the requisite attribution period and the estimate will be reassessed at the end of each performance period which will reflect any adjustments in the consolidated statements of comprehensive income in the period in which they are determined.
	The Company recognized share compensation expenses during the three and nine months ended September 30, 2014 of $315 (2013: $318) and $549 (2013: ($971)), respectively. The negative expense is due to a reversal of expenses on unvested performance share awards based on a review of current and projected performance criteria.
	Activity with respect to unvested performance share awards for the nine months ended September 30, 2014 was as follows:
		Performance Share Awards		Weighted Average Grant Date Fair Value
	Performance share awards outstanding, December 31, 2013	101,820		$	33.56
	Performance share awards granted	52,639		37.33
Performance share awards vested	(32,746	)	32.62
Performance share awards conversion adjustment	(15,344	)	31.38
Performance share awards outstanding, September 30, 2014	106,369		$	36.03
Activity with respect to unvested performance share awards for the nine months ended September 30, 2013 was as follows:
	Performance Share Awards		Weighted Average Grant Date Fair Value
Performance share awards outstanding, December 31, 2012	220,845		$	31.81
Performance share awards granted	38,386		36.11
Performance share awards vested	(39,094	)	28.7
Performance share awards forfeited	(18,701	)	31.05
Performance share awards conversion adjustment	(99,616	)	$	33.05
Performance share awards outstanding, September 30, 2013	101,820		$	33.56
At September 30, 2014, there were $2,527 (December 31, 2013: $1,642) of total unrecognized share compensation expenses in respect of performance share awards that are expected to be recognized over a weighted-average period of 2.3 years (December 31, 2013: 2.0 years).
(b)	Total share compensation expenses
The breakdown of share compensation expenses by award type was as follows:
	Three Months Ended						Nine Months Ended
	September 30,			September 30,			September 30,		September 30,
	2014			2013			2014		2013
Restricted share awards	8,180			10,041			23,101		20,035
Restricted share units	269			168			602		419
Performance share awards	315			318			549		(971		)
Total	$	8,764		$	10,527		$	24,252	$	19,483

Debt_and_financing_arrangement

Debt and financing arrangements	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Debt and financing arrangements	'
	Debt and financing arrangements
	(a)	Financing structure
	The financing structure at September 30, 2014 was:
		Commitment			Issued and outstanding (a)				Drawn
	2006 Junior Subordinated Deferrable Debentures	$	150,000		$	150,000			$	150,000
	2007 Junior Subordinated Deferrable Debentures	200,000			139,800				139,800
	Flagstone 2006 Junior Subordinated Deferrable Debentures	136,403			136,403				136,403
	Flagstone 2007 Junior Subordinated Deferrable Debentures	113,750			113,750				113,750
	Total debentures payable	600,153			539,953				539,953
	2010 Senior Notes due 2040	250,000			250,000				247,279
	Total debentures and senior notes payable	850,153			789,953				787,232
	$400,000 syndicated unsecured letter of credit facility	400,000			—				—
	$525,000 syndicated secured letter of credit facility	525,000			301,340				—
	$200,000 secured bi-lateral letter of credit facility	200,000			19,743				—
	Talbot FAL facility	25,000			25,000				—
	PaCRe senior secured letter of credit facility	10,000			294				—
	AlphaCat Re secured letter of credit facility	30,000			30,000				—
	IPC bi-lateral facility	40,000			16,975				—
	$375,000 Flagstone bi-lateral facility	375,000			288,739				—
	Total credit and other facilities	1,605,000			682,091				—
	Total debt and financing arrangements	$	2,455,153		$	1,472,044			$	787,232
	The financing structure at December 31, 2013 was:
		Commitment			Issued and outstanding (a)				Drawn
	2006 Junior Subordinated Deferrable Debentures	$	150,000		$	150,000			$	150,000
	2007 Junior Subordinated Deferrable Debentures	200,000			139,800				139,800
	Flagstone 2006 Junior Subordinated Deferrable Debentures	137,866			137,866				137,866
	Flagstone 2007 Junior Subordinated Deferrable Debentures	113,750			113,750				113,750
	Total debentures payable	601,616			541,416				541,416
	2010 Senior Notes due 2040	250,000			250,000				247,198
	Total debentures and senior notes payable	851,616			791,416				788,614
	$400,000 syndicated unsecured letter of credit facility	400,000			—				—
	$525,000 syndicated secured letter of credit facility	525,000			358,567				—
	$200,000 secured bi-lateral letter of credit facility	200,000			16,726				—
	Talbot FAL facility	25,000			25,000				—
	PaCRe senior secured letter of credit facility	10,000			294				—
	AlphaCat Re secured letter of credit facility	24,800			24,800				—
	IPC bi-lateral facility	40,000			20,177				—
	$375,000 Flagstone bi-lateral facility	375,000			305,686				—
	Total credit and other facilities	1,599,800			751,250				—
	Total debt and financing arrangements	$	2,451,416		$	1,542,666			$	788,614
	(a)	Indicates utilization of commitment amount, not necessarily drawn borrowings.
	(b)	Senior notes and junior subordinated deferrable debentures
	The following table summarizes the key terms of the Company's senior notes and junior subordinated deferrable debentures as at the issuance date for each placement.
	Description	Issuance date	Commitment		Maturity date	Fixed/Spread			Interest payments due
	2006 Junior Subordinated Deferrable Debentures	June 15, 2006	$	150,000	June 15, 2036	9.069	%	(a)	Quarterly
	Flagstone 2006 Junior Subordinated Deferrable Debentures	August 23, 2006	$	136,403	September 15, 2036	3.54	%	(b)	Quarterly
	2007 Junior Subordinated Deferrable Debentures	June 21, 2007	$	200,000	June 15, 2037	8.48	%	(a)	Quarterly
	Flagstone 2007 Junior Subordinated Deferrable Debentures	June 8, 2007	$	88,750	July 30, 2037	3	%	(b)	Quarterly
	Flagstone 2007 Junior Subordinated Deferrable Debentures	September 20, 2007	$	25,000	September 15, 2037	3.1	%	(b)	Quarterly
	2010 Senior Notes due 2040	January 26, 2010	$	250,000	January 26, 2040	8.875	%	(a)	Semi-annually in arrears
	(a)	Fixed interest rate.
	(b)	Variable interest rate is the three-month LIBOR, reset quarterly, plus spread as noted in the table.
	The following table summarizes the key terms of the Company's senior notes and junior subordinated deferrable debentures as at September 30, 2014:
	Description	Issuance date	Commitment		Maturity date	Fixed/Spread			Interest payments due
	2006 Junior Subordinated Deferrable Debentures	June 15, 2006	$	150,000	June 15, 2036	5.831	%	(b)	Quarterly
	Flagstone 2006 Junior Subordinated Deferrable Debentures	August 23, 2006	$	136,403	September 15, 2036	6.463	%	(b)	Quarterly
	2007 Junior Subordinated Deferrable Debentures	June 21, 2007	$	200,000	June 15, 2037	5.18	%	(b)	Quarterly
	Flagstone 2007 Junior Subordinated Deferrable Debentures	8-Jun-07	$	88,750	July 30, 2037	5.9	%	(b)	Quarterly
	Flagstone 2007 Junior Subordinated Deferrable Debentures	20-Sep-07	$	25,000	September 15, 2037	5.983	%	(b)	Quarterly
	2010 Senior Notes due 2040	26-Jan-10	$	250,000	January 26, 2040	8.875	%	(a)	Semi-annually in arrears
	(a)	Fixed interest rate.
	(b)	Interest rate has been fixed as a result of interest rate swap contracts entered into by the Company.
	Senior Notes
The Senior Notes due 2040 (the “2010 Senior Notes”) were part of a registered public offering. The 2010 Senior Notes mature on January 26, 2040.  The Company may redeem the notes, in whole at any time, or in part from time to time, at the Company's option on not less than 30 nor more than 60 days’ notice, at a make-whole redemption price as described in “Description of the Notes - Optional Redemption” in the 2010 Senior Notes prospectus supplement.  In addition, the Company may redeem the notes, in whole, but not in part, at any time upon the occurrence of certain tax events as described in “Description of the Notes - Redemption for Tax Purposes’ in the prospectus supplement.
Debt issuance costs were deferred as an asset and are amortized over the life of the 2010 Senior Notes. There were no redemptions made during the three and nine months ended September 30, 2014 and 2013.
The 2010 Senior Notes are unsecured and unsubordinated obligations of the Company and rank equally in right of payment with all of the Company’s existing and future unsecured and unsubordinated indebtedness. The 2010 Senior Notes will be effectively junior to all of the Company’s future secured debt, to the extent of the value of the collateral securing such debt, and will rank senior to all our existing and future subordinated debt. The 2010 Senior Notes are structurally subordinated to all obligations of the Company’s subsidiaries.
Future payments of principal of $250,000 on the 2010 Senior Notes are all expected to be after 2019.
Junior subordinated deferrable debentures
The Company participated in private placements of junior subordinated deferrable interest debentures due 2036 and 2037 (respectively, the “2006 Junior Subordinated Deferrable Debentures” and “2007 Junior Subordinated Deferrable Debentures”).
Debt issuance costs for the 2006 and 2007 Junior Subordinated Deferrable Debentures were deferred as an asset and were amortized to income over the five year optional redemption periods. They are redeemable at the Company's option at par. There were no redemptions made during the three and nine months ended September 30, 2014 and 2013.
As part of the acquisition of Flagstone, the Company assumed junior subordinated deferrable debentures due 2036 and 2037 (respectively, the “Flagstone 2006 Junior Subordinated Deferrable Debentures” and “Flagstone 2007 Junior Subordinated Deferrable Debentures”). These debentures are redeemable quarterly at par. There were no redemptions made during the three and nine months ended September 30, 2014 and 2013.
Future payments of principal of $539,953 on the debentures discussed above are all expected to be after 2019.
(c)	Credit facilities
i.	$400,000 syndicated unsecured letter of credit facility and $525,000 syndicated secured letter of credit facility
On March 9, 2012, the Company entered into a $400,000 four-year unsecured credit facility with Deutsche Bank Securities Inc., as syndication agent, JPMorgan Chase Bank, N.A. as administrative agent, Lloyds Securities Inc. and Suntrust Bank, as co-documentation agents and the lenders party thereto, which provides for letter of credit and revolving credit availability for the Company (the “Four Year Unsecured Facility”) (the full $400,000 of which is available for letters of credit and/or revolving loans). The Four Year Unsecured Facility was provided by a syndicate of commercial banks. Letters of credit under the Four Year Unsecured Facility are available to support obligations in connection with the insurance business of the Company and its subsidiaries. Loans under the Four Year Unsecured Facility are available for the general corporate and working capital purposes of the Company. The Company may request that existing lenders under the Four Year Unsecured Facility or prospective additional lenders agree to make available additional commitments from time to time so long as the aggregate commitments under the Four Year Unsecured Facility do not exceed $500,000.
Also on March 9, 2012, the Company entered into a $525,000 four-year secured credit facility, with the same parties, which provides for letter of credit availability for the Company (the “Four Year Secured Facility” and together with the Four Year Unsecured Facility, the “Credit Facilities”). The Four Year Secured Facility was also provided by a syndicate of commercial banks. Letters of credit under the Four Year Secured Facility will be available to support obligations in connection with the insurance business of the Company. The Company may request that existing lenders under the Four Year Secured Facility or prospective additional lenders agree to make available additional commitments from time to time so long as the aggregate commitments under the Four Year Secured Facility do not exceed $700,000. The obligations of the Company under the Four Year Secured Facility are secured by cash and securities deposited into cash collateral accounts from time to time with The Bank of New York Mellon.
As of September 30, 2014, there were $301,340 in outstanding letters of credit under the Four Year Secured Facility (December 31, 2013: $358,567) and $nil outstanding under the Four Year Unsecured Facility.
The Credit Facilities contain covenants that include, among other things (i) the requirement that the Company initially maintain a minimum level of consolidated net worth of at least $2,600,000 and, commencing with the end of the fiscal quarter ending March 31, 2012, to be increased quarterly by an amount equal to 50.0% of the Company’s consolidated net income (if positive) for such quarter plus 50.0% of the aggregate increases in the consolidated shareholders’ equity of the Company during such fiscal quarter by reason of the issuance and sale of common equity interests of the Company, including upon any conversion of debt securities of the Company into such equity interests, (ii) the requirement that the Company maintain at all times a consolidated total debt to consolidated total capital ratio not greater than 0.35:1.00, and (iii) the requirement that Validus Reinsurance, Ltd. and any other material insurance subsidiaries maintain a financial strength rating by A.M. Best of not less than “B++” (Fair).  In addition, the Credit Facilities contain customary negative covenants applicable to the Company, including limitations on the ability to pay dividends and other payments in respect of equity interests at any time that the Company is otherwise in default with respect to certain provisions under the respective Credit Facilities, limitations on the ability to incur liens, sell assets, merge or consolidate with others, enter into transactions with affiliates, and limitations on the ability of its subsidiaries to incur indebtedness. The Credit Facilities also contain customary affirmative covenants, representations and warranties and events of default for credit facilities of its type. As of September 30, 2014, and throughout the reporting periods presented, the Company was in compliance with all covenants and restrictions under the Credit Facilities.
ii.	$25,000 Talbot FAL facility
Talbot holds a standby Letter of Credit facility (the “Talbot FAL facility”) to provide Funds at Lloyd’s to support the 2012, 2013, 2014 and 2015 underwriting years of account. As of September 30, 2014 the Company had $25,000 (December 31, 2013: $25,000) in outstanding letters of credit under the Talbot FAL facility.
The Talbot FAL facility contains affirmative covenants that include requirements for consolidated net worth and debt to capital ratios in line with those in place for the Credit Facilities and discussed above. The Talbot FAL facility also contains restrictions on the Company's ability to incur debt at our subsidiaries, incur liens, sell assets and merge or consolidate with others. Other than in respect of existing and future preferred and hybrid securities, the payment of dividends and other payments in respect of equity interests are not permitted at any time that we are in default with respect to certain provisions under the Talbot FAL facility. As of September 30, 2014 and throughout the reporting periods presented, the Company was in compliance with all covenants and restrictions under the Talbot FAL facility.
iii.	$40,000 IPC bi-lateral facility
The Company assumed an existing evergreen letter of credit facility through the acquisition of IPC Holdings, Ltd. (the "IPC bi-lateral facility"). As of September 30, 2014, there were $16,975 outstanding letters of credit issued under the IPC bi-lateral facility (December 31, 2013: $20,177). As of September 30, 2014 and throughout the reporting periods presented, the Company was in compliance with all covenants and restrictions under the IPC bi-lateral facility.
iv.	$200,000 secured bi-lateral letter of credit facility
The Company holds an uncommitted secured bi-lateral letter of credit facility with Citibank Europe plc (the “Secured bi-lateral letter of credit facility”). As of September 30, 2014, $19,743 (December 31, 2013: $16,726) of letters of credit were outstanding under the Secured bi-lateral letter of credit facility. The Secured bi-lateral letter of credit facility has no fixed termination date and as of September 30, 2014, and throughout the reporting periods presented, the Company is in compliance with all terms and covenants thereof.
v.	$10,000 PaCRe senior secured letter of credit facility
On May 11, 2012, PaCRe and its subsidiary, PaCRe Investments, Ltd. entered into a secured evergreen credit and letter of credit facility with JPMorgan Chase Bank, N.A. This facility provides for revolving borrowings by PaCRe and for letters of credit issued by PaCRe to be used to support its reinsurance obligations in aggregate amount of $10,000. As of September 30, 2014, $294 (December 31, 2013: $294) of letters of credit were outstanding under this facility. As of September 30, 2014, and throughout the reporting periods presented, PaCRe was in compliance with all covenants and restrictions thereof.
vi.	$30,000 AlphaCat Re secured letter of credit facility
On January 2, 2013, AlphaCat Re entered into a secured evergreen letter of credit facility with Comerica Bank. This facility provides for letters of credit issued by AlphaCat Re to be used to support its reinsurance obligations in the aggregate amount of $24,800. During the period ended March 31, 2014 the size of the facility was increased to $30,000 from $24,800. As of September 30, 2014, $30,000 (December 31, 2013: $24,800) of letters of credit were outstanding under this facility. As of September 30, 2014, and throughout the reporting periods presented, AlphaCat Re was in compliance with all covenants and restrictions thereof.
vii.	$375,000 Flagstone bi-lateral facility
As part of the Flagstone Acquisition, the Company assumed an evergreen Letters of Credit Master Agreement between Citibank Europe Plc and Flagstone Reassurance Suisse, S.A. (the “Flagstone Bi-Lateral Facility”). At September 30, 2014, the Flagstone Bi-Lateral Facility had $288,739 (December 31, 2013: $305,686) letters of credit issued and outstanding. As of September 30, 2014, and throughout the reporting periods presented, the Company was in compliance with all covenants and restrictions under the Flagstone Bi-Lateral Facility.
(d)	Finance expenses
Finance expenses consist of interest on the junior subordinated deferrable debentures and senior notes, the amortization of debt offering costs, credit facilities fees, bank charges, AlphaCat financing fees and Talbot FAL costs as follows:
	Three Months Ended							Nine Months Ended
	September 30,			September 30,				September 30,			September 30,
	2014			2013				2014			2013
2006 Junior Subordinated Deferrable Debentures	$	2,235		$	2,235			$	6,633		$	6,633
2007 Junior Subordinated Deferrable Debentures	1,848			1,848				5,492			5,492
Flagstone 2006 Junior Subordinated Deferrable Debentures	2,269			2,285				6,736			5,988
Flagstone 2007 Junior Subordinated Deferrable Debentures	1,807			1,807				5,335			4,426
2010 Senior Notes due 2040	5,597			5,597				16,791			16,791
Credit facilities	1,295			1,248				4,225			5,001
Bank charges	88			187				303			420
AlphaCat ILS funds fees (a)	384			78				2,030			2,406
Talbot FAL Facility	(169		)	32				(165		)	95
Total finance expenses	$	15,354		$	15,317			$	47,380		$	47,252
(a)	Includes finance expenses incurred by AlphaCat Managers, Ltd. in relation to fund raising for the AlphaCat ILS funds, AlphaCat 2014 and AlphaCat 2013.

Accumulated_other_comprehensiv

Accumulated other comprehensive (loss) income	9 Months Ended
	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'
Accumulated other comprehensive (loss) income	'
	Accumulated other comprehensive (loss) income
	The changes in accumulated other comprehensive (loss) income, by component for the three and nine months ended September 30, 2014 and 2013 is as follows:
		Three Months Ended						Nine Months Ended
		September 30,			September 30,			September 30,			September 30,
		2014			2013			2014			2013
	Balance - Beginning of period	$	2,460		$	(8,262	)	$	(617	)	$	(2,953	)
	Amounts reclassified to retained earnings	—			—			—			4,290
	Other comprehensive (loss) income	(5,198		)	4,390			(2,121		)	(5,209		)
	Balance - End of period	$	(2,738	)	$	(3,872	)	$	(2,738	)	$	(3,872	)

Commitments_and_contingencies

Commitments and contingencies	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and contingencies	'
	Commitments and contingencies
	(a)	Concentrations of credit risk
	The Company’s investments are managed following prudent standards of diversification. The Company attempts to limit its credit exposure by purchasing high quality fixed income investments to maintain a minimum weighted-average portfolio credit rating of A+. In addition, the portfolio limits the amount of “risk assets”, such as non-investment grade debt and equity securities, to a maximum of 35% of shareholders’ equity. The Company also limits its exposure to any single issuer to 3.5% of its investment portfolio or less, excluding government and agency securities, depending on the credit rating of the issuer. With the exception of the Company's bank loan portfolio, which represents 6.8% of the Company's total investments as at September 30, 2014, and certain capital securities issued by investment grade corporations, the minimum credit rating of any security purchased is Baa3/BBB-. In total, investments in below investment grade securities are limited to no more than 10% of the Company's investment portfolio. Excluding bank loans, 1.7% of the portfolio had a split rating below Baa3/BBB- as at September 30, 2014. The Company did not have an aggregate exposure to any single issuer of more than 0.9% of its investment portfolio, other than with respect to government and agency securities as at September 30, 2014.
	(b)	Funds at Lloyd's
	The amounts provided under the Talbot FAL Facility would become a liability of the Company in the event of Syndicate 1183 declaring a loss at a level which would call on this arrangement.
	Talbot operates in Lloyd’s through a corporate member, Talbot 2002 Underwriting Capital Ltd (“T02”), which is the sole participant in Syndicate 1183. Lloyd’s sets T02’s required capital annually based on Syndicate 1183’s business plan, rating environment and reserving environment together with input arising from Lloyd’s discussions with, inter alia, regulatory and rating agencies. Such capital, called Funds at Lloyd’s (“FAL”), comprises: cash, investments and undrawn letters of credit provided by various banks.
	The amounts of cash, investments and letters of credit provided for each year of account as follows:
		2014 Underwriting Year		2013 Underwriting Year
	Talbot FAL facility	$	25,000	$	25,000
	Group funds	450,000		403,700
	Total	$	475,000	$	428,700
	The amounts which are provided as FAL are not available for distribution to the Company for the payment of dividends. Talbot’s corporate member 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. See Note 3 (d) for investments pledged as collateral.
	(c)	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 2014 estimated premium income at Lloyd's of £625,000, at the September 30, 2014 exchange rate of £1 equals $1.6195 and assuming the maximum 3% assessment, the Company would be assessed approximately $30,366.
	(d)	Aquiline commitment
	As discussed in Note 5 "Investments in affiliates," the Company entered into an Assignment and Assumption Agreement with Aquiline Capital Partners LLC, pursuant to which it assumed a total capital commitment of $50,000 which will expire on July 2, 2015. The Company's remaining commitment at September 30, 2014 was $17,890 (December 31, 2013: $17,890).
	(e)	Other investment commitments
	At September 30, 2014, the Company had capital commitments to five other investments of $105,000 (December 31, 2013: $30,000). The Company's remaining commitment to these investments at September 30, 2014 was $79,259 (December 31, 2013: $5,045).

Related_party_transactions

Related party transactions	9 Months Ended
	Sep. 30, 2014
Related Party Transactions [Abstract]	'
Related party transactions	'
	Related party transactions
	The transactions listed below are classified as related party transactions as each counter party has either a direct or indirect shareholding in the Company.
	Aquiline Capital Partners, LLC and its related companies ("Aquiline"), which own 3,446,643 shares in the Company, hold warrants to purchase 2,756,088 shares, and have two employees on the Company's Board of Directors who do not receive compensation from the Company, are shareholders of Group Ark Insurance Holdings Ltd. ("Group Ark"). Christopher E. Watson, a director of the Company, serves as a director of Group Ark. Pursuant to reinsurance agreements with a subsidiary of Group Ark, the Company recognized gross premiums written during the three and nine months ended September 30, 2014 of $246 (2013: $nil) and $2,190 (2013: $2,848) respectively, with $733 included in premiums receivable at September 30, 2014 (December 31, 2013: $238). The Company also recognized reinsurance premiums ceded during the three and nine months ended September 30, 2014 of $127 (2013: $23) and had reinsurance balances payable of $4 at September 30, 2014 (December 31, 2013: $4). The Company recorded $2,005 of loss reserves recoverable at September 30, 2014 (December 31, 2013: $3,698). Earned premium adjustments of $694 (2013: $718) and $1,653 (2013: $2,147) were recorded during the three and nine months ended September 30, 2014, respectively.
	On November 24, 2009, the Company entered into an Investment Management Agreement with Conning, Inc. ("Conning") to manage a portion of the Company's investment portfolio. Aquiline acquired Conning on June 16, 2009. Jeffrey W. Greenberg, a director of the Company, serves as a director of Conning Holdings Corp., the parent company of Conning. Investment management fees earned by Conning for the three and nine months ended September 30, 2014 were $(7) (2013: $165) and $219 (2013: $396) respectively, with $239 included in accounts payable and accrued expenses at September 30, 2014 (December 31, 2013: $283).
	On December 20, 2011, the Company entered into an Assignment and Assumption Agreement (the "Agreement") with Aquiline Capital Partners LLC, a Delaware limited liability company (the "Assignor") and Aquiline Capital Partners II GP (Offshore) Ltd., a Cayman Islands company limited by shares (the "General Partner") pursuant to which the Company has assumed 100% of the Assignor's interest in Aquiline Financial Services Fund II L.P. (the "Partnership") representing a total capital commitment of $50,000 (the "Commitment"), as a limited partner in the Partnership (the "Transferred Interest"). Messrs. Greenberg and Watson, directors of the Company, serve as managing principal and senior principal, respectively, of Aquiline Capital Partners LLC. For the three months ended September 30, 2014, the Company incurred $nil (2013: $505) in partnership fees and made capital contributions of $nil (2013: $6,185). For the nine months ended September 30, 2014, the Company incurred $nil (2013: $625) in partnership fees and made $nil (2013: $13,089) of capital contributions. There were no amounts included in accounts payable and accrued expenses at September 30, 2014 or December 31, 2013.
	Certain shareholders of the Company and their affiliates, as well as employers of entities associated with directors or officers have purchased insurance and/or reinsurance from the Company in the ordinary course of business. The Company believes these transactions were settled for arm's length consideration.

Earnings_per_share

Earnings per share	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Earnings per share	'
	Earnings per share
	The following table sets forth the computation of basic and earnings per diluted share for the three and nine months ended September 30, 2014 and 2013:
		Three Months Ended						Nine Months Ended
		September 30,			September 30,			September 30,			September 30,
		2014			2013			2014			2013
	Basic earnings per share
	Net (loss) income	$	(13,397	)	$	229,063		$	381,172		$	419,503
	Loss (income) attributable to noncontrolling interest	53,069			(45,694		)	(25,745		)	17,831
	Net income available to Validus	39,672			183,369			355,427			437,334
	Less: Dividends and distributions declared on outstanding warrants	(1,552		)	(1,552		)	(4,656		)	(17,662		)
	Income available to common shareholders	$	38,120		$	181,817		$	350,771		$	419,672
	Weighted average number of common shares outstanding	90,593,329			99,834,563			91,665,950			103,451,396
	Basic earnings per share available to common shareholders	$	0.42		$	1.82		$	3.83		$	4.06
	Earnings per diluted share
	Net (loss) income	$	(13,397	)	$	229,063		$	381,172		$	419,503
	Loss (income) attributable to noncontrolling interest	53,069			(45,694		)	(25,745		)	17,831
	Net income available to Validus	39,672			183,369			355,427			437,334
	Less: Dividends and distributions declared on outstanding warrants	(1,552		)	—			—			(17,662		)
	Income available to common shareholders	$	38,120		$	183,369		$	355,427		$	419,672
	Weighted average number of common shares outstanding	90,593,329			99,834,563			91,665,950			103,451,396
	Share equivalents:
	Warrants	—			2,606,669			2,747,399			—
	Stock options	760,267			782,158			752,145			1,090,298
	Unvested restricted shares	586,014			390,376			772,147			723,219
	Weighted average number of diluted common shares outstanding	91,939,610			103,613,766			95,937,641			105,264,913
	Earnings per diluted share available to common shareholders	$	0.41		$	1.77		$	3.7		$	3.99
	Share equivalents that would result in the issuance of common shares of 4,712 (2013: 125,728) and 235,460 (2013: 464,516) were outstanding for the three and nine months ended September 30, 2014, respectively, but were not included in the computation of earnings per diluted share because the effect would be antidilutive.

Segment_information

Segment information	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Segment information	'
	Segment information
	The Company conducts its operations worldwide through three operating segments, which have been determined under U.S. GAAP segment reporting to be Validus Re, AlphaCat and Talbot. The Company’s operating segments are strategic business units that offer different products and services. They are managed and have capital allocated separately because each segment requires different strategies.
	Validus Re Segment
	The Validus Re segment is focused on short-tail lines of reinsurance. The primary lines in which the segment conducts business are property, marine and specialty which includes agriculture, aerospace and aviation, financial lines of business, nuclear, terrorism, life, accident & health, workers’ compensation, crisis management, contingency, motor, technical lines, composite and trade credit.
	AlphaCat Segment
	The AlphaCat segment manages strategic relationships that leverage the Company’s underwriting and investment expertise and earns management, performance and underwriting fees primarily from the Company’s operating affiliates, AlphaCat Re 2011, AlphaCat Re 2012, AlphaCat 2013 and AlphaCat 2014, as well as PaCRe and the AlphaCat ILS funds.
	Talbot Segment
	The Talbot segment focuses on a wide range of marine and energy, war, political violence, commercial property, financial institutions, contingency, accident & health and aviation classes of business on an insurance or facultative reinsurance basis and principally property, aerospace and marine classes of business on a treaty reinsurance basis.
	Corporate and eliminations
	The Company has a corporate function ("corporate"), which includes the activities of the parent company, and which carries out certain functions for the group. Corporate includes ‘non-core’ underwriting expenses, predominantly general and administrative and stock compensation expenses. Corporate also denotes the activities of certain key executives such as the Chief Executive Officer and Chief Financial Officer. For internal reporting purposes, corporate is reflected separately, however corporate is not considered an operating segment under these circumstances. Other reconciling items include, but are not limited to, the elimination of inter segment revenues and expenses and unusual items that are not allocated to segments.
	The following tables summarize the results of our operating segments and "Corporate":
	Three Months Ended September 30, 2014		Validus Re Segment				AlphaCat Segment				Talbot Segment				Corporate & Eliminations				Total
	Underwriting income
	Gross premiums written		$	114,897			$	6,936			$	245,685			$	(8,544	)		$	358,974
	Reinsurance premiums ceded		(10,899		)		(648		)		(27,134		)		8,544				(30,137		)
	Net premiums written		103,998				6,288				218,551				—				328,837
	Change in unearned premiums		122,712				28,850				14,297				—				165,859
	Net premiums earned		226,710				35,138				232,848				—				494,696
	Underwriting deductions
	Losses and loss expenses		102,005				3,738				118,382				—				224,125
	Policy acquisition costs		36,177				3,378				47,862				(1,013		)		86,404
	General and administrative expenses		18,522				7,719				37,709				19,369				83,319
	Share compensation expenses		2,582				179				2,990				3,013				8,764
	Total underwriting deductions		159,286				15,014				206,943				21,369				402,612
	Underwriting income (loss)		$	67,424			$	20,124			$	25,905			$	(21,369	)		$	92,084
	Net investment income		20,762				837				4,965				(1,303		)		25,261
	Other (loss) income		(6,827		)		5,980				109				(3,342		)		(4,080		)
	Finance expenses		(3,622		)		(385		)		162				(11,509		)		(15,354		)
	Operating income (loss) before taxes, income from operating affiliates and (income) attributable to operating affiliate investors		77,737				26,556				31,141				(37,523		)		97,911
	Tax benefit (expense)		1,058				—				332				(437		)		953
	Income from operating affiliates		—				3,761				—				—				3,761
	(Income) attributable to operating affiliate investors		—				(25,807		)		—				—				(25,807		)
	Net operating income (loss)		$	78,795			$	4,510			$	31,473			$	(37,960	)		$	76,818
	Net realized gains on investments		1,641				2,563				391				—				4,595
	Change in net unrealized (losses) on investments		(20,149		)		(60,253		)		(3,097		)		(1,475		)		(84,974		)
	Income from investment affiliate		1,754				—				—				—				1,754
	Foreign exchange (losses) gains		(6,056		)		(51		)		(7,114		)		1,780				(11,441		)
	Transaction expenses (b)		—				—				—				(149		)		(149		)
	Net income (loss)		$	55,985			$	(53,231	)		$	21,653			$	(37,804	)		$	(13,397	)
	Net loss attributable to noncontrolling interest		—				53,069				—				—				53,069
	Net income (loss) available (attributable) to Validus		$	55,985			$	(162	)		$	21,653			$	(37,804	)		$	39,672
	Selected ratios (a):
	Net premiums written / Gross premiums written		90.5		%		90.7		%		89		%						91.6		%
	Losses and loss expenses		45		%		10.6		%		50.8		%						45.3		%
	Policy acquisition costs		16		%		9.6		%		20.6		%						17.5		%
	General and administrative expenses (c)		9.3		%		22.5		%		17.5		%						18.6		%
	Expense ratio		25.3		%		32.1		%		38.1		%						36.1		%
	Combined ratio		70.3		%		42.7		%		88.9		%						81.4		%
	Total assets		$	4,716,426			$	1,688,191			$	2,898,755			$	749,678			$	10,053,050
	(a)	Ratios are based on net premiums earned.
	(b)	The transaction expenses relate to costs incurred in connection with the acquisition of Western World, which was completed on October 2, 2014. Western World results have not been included in the Company's consolidated results for the three months ended September 30, 2014. Transaction expenses are primarily comprised of legal, financial advisory and audit related services.
	(c)	The general and administrative expense ratio includes share compensation expenses.
	Three Months Ended September 30, 2013		Validus Re Segment				AlphaCat Segment				Talbot Segment				Corporate & Eliminations				Total
	Underwriting income
	Gross premiums written		$	130,925			$	3,481			$	246,468			$	(24,114	)		$	356,760
	Reinsurance premiums ceded		(13,006		)		(525		)		(49,998		)		24,114				(39,415		)
	Net premiums written		117,919				2,956				196,470				—				317,345
	Change in unearned premiums		157,873				34,210				21,860				—				213,943
	Net premiums earned		275,792				37,166				218,330				—				531,288
	Underwriting deductions
	Losses and loss expenses		62,250				15,615				100,100				—				177,965
	Policy acquisition costs		47,662				3,787				44,899				(1,448		)		94,900
	General and administrative expenses		19,785				5,728				37,402				18,174				81,089
Share compensation expenses		2,479				152				2,992				4,904				10,527
Total underwriting deductions		132,176				25,282				185,393				21,630				364,481
Underwriting income (loss)		$	143,616			$	11,884			$	32,937			$	(21,630	)		$	166,807
Net investment income		15,628				967				4,395				(981		)		20,009
Other (loss) income		(1,892		)		3,791				73				(4,778		)		(2,806		)
Finance expenses		(3,640		)		(80		)		(107		)		(11,490		)		(15,317		)
Operating income (loss) before taxes, income from operating affiliates and (income) attributable to operating affiliate investors		153,712				16,562				37,298				(38,879		)		168,693
Tax benefit (expense)		143				—				(513		)		365				(5		)
Income from operating affiliates		—				1,463				—				—				1,463
(Income) attributable to operating affiliate investors		—				(11,815		)		—				—				(11,815		)
Net operating income (loss)		$	153,855			$	6,210			$	36,785			$	(38,514	)		$	158,336
Net realized (losses) gains on investments		(10,137		)		4,084				(267		)		—				(6,320		)
Change in net unrealized gains on investments		23,144				44,145				2,678				—				69,967
Income from investment affiliate		1,044				—				—				—				1,044
Foreign exchange gains (losses)		2,168				388				4,238				(758		)		6,036
Net income (loss)		$	170,074			$	54,827			$	43,434			$	(39,272	)		$	229,063
Net income attributable to noncontrolling interest		—				(45,694		)		—				—				(45,694		)
Net income (loss) available (attributable) to Validus		$	170,074			$	9,133			$	43,434			$	(39,272	)		$	183,369
Selected ratios (a):
Net premiums written / Gross premiums written		90.1		%		84.9		%		79.7		%						89		%
Losses and loss expenses		22.6		%		42		%		45.8		%						33.5		%
Policy acquisition costs		17.3		%		10.2		%		20.6		%						17.9		%
General and administrative expenses (b)		8.1		%		15.8		%		18.5		%						17.2		%
Expense ratio		25.4		%		26		%		39.1		%						35.1		%
Combined ratio		48		%		68		%		84.9		%						68.6		%
Total assets		$	5,854,354			$	1,446,941			$	2,892,477			$	123,596			$	10,317,368
(a)	Ratios are based on net premiums earned.
(b)	The general and administrative expense ratio includes share compensation expenses.
Nine Months Ended September 30, 2014		Validus Re Segment				AlphaCat Segment				Talbot Segment				Corporate & Eliminations				Total
Underwriting income
Gross premiums written		$	1,104,169			$	135,073			$	854,324			$	(66,927	)		$	2,026,639
Reinsurance premiums ceded		(184,074		)		(4,348		)		(154,115		)		66,927				(275,610		)
Net premiums written		920,095				130,725				700,209				—				1,751,029
Change in unearned premiums		(233,271		)		(32,444		)		(41,658		)		—				(307,373		)
Net premiums earned		686,824				98,281				658,551				—				1,443,656
Underwriting deductions
Losses and loss expenses		247,848				(7,155		)		304,848				—				545,541
Policy acquisition costs		106,547				9,414				138,383				(3,338		)		251,006
General and administrative expenses		53,757				15,627				107,031				55,191				231,606
Share compensation expenses		7,126				330				8,434				8,362				24,252
Total underwriting deductions		415,278				18,216				558,696				60,215				1,052,405
Underwriting income (loss)		$	271,546			$	80,065			$	99,855			$	(60,215	)		$	391,251
Net investment income		56,285				2,546				14,322				(3,244		)		69,909
Other income (loss)		912				21,482				384				(7,793		)		14,985
Finance expenses		(11,131		)		(2,039		)		68				(34,278		)		(47,380		)
Operating income (loss) before taxes, income from operating affiliates and (income) attributable to operating affiliate investors		317,612				102,054				114,629				(105,530		)		428,765
Tax benefit (expense)		1,176				—				(902		)		(672		)		(398		)
Income from operating affiliates		—				13,580				—				—				13,580
(Income) attributable to operating affiliate investors		—				(82,833		)		—				—				(82,833		)
Net operating income (loss)		$	318,788			$	32,801			$	113,727			$	(106,202	)		$	359,114
Net realized gains on investments		5,411				10,230				552				—				16,193
Change in net unrealized gains (losses) on investments		5,279				15,706				2,159				(6,998		)		16,146
Income from investment affiliate		7,881				—				—				—				7,881
Foreign exchange (losses) gains		(9,384		)		(204		)		(5,897		)		724				(14,761		)
Transaction expenses (b)		—				—				—				(3,401		)		(3,401		)
Net income (loss)		$	327,975			$	58,533			$	110,541			$	(115,877	)		$	381,172
Net (income) attributable to noncontrolling interest		—				(25,745		)		—				—				(25,745		)
Net income (loss) available (attributable) to Validus		$	327,975			$	32,788			$	110,541			$	(115,877	)		$	355,427
Selected ratios (a):
Net premiums written / Gross premiums written		83.3		%		96.8		%		82		%						86.4		%
Losses and loss expenses		36.1		%		(7.3		)%		46.3		%						37.8		%
Policy acquisition costs		15.5		%		9.6		%		21		%						17.4		%
General and administrative expenses (c)		8.9		%		16.2		%		17.5		%						17.7		%
Expense ratio		24.4		%		25.8		%		38.5		%						35.1		%
Combined ratio		60.5		%		18.5		%		84.8		%						72.9		%
Total assets		$	4,716,426			$	1,688,191			$	2,898,755			$	749,678			$	10,053,050
(a)	Ratios are based on net premiums earned.
(b)	The transaction expenses relate to costs incurred in connection with the acquisition of Western World, which was completed on October 2, 2014. Western World results have not been included in the Company's consolidated results for the nine months ended September 30, 2014. Transaction expenses are primarily comprised of legal, financial advisory and audit related services.
(c)	The general and administrative expense ratio includes share compensation expenses.
Nine Months Ended September 30, 2013		Validus Re Segment				AlphaCat Segment				Talbot Segment				Corporate & Eliminations				Total
Underwriting income
Gross premiums written		$	1,232,272			$	146,757			$	855,516			$	(70,712	)		$	2,163,833
Reinsurance premiums ceded		(226,292		)		(525		)		(191,922		)		70,712				(348,027		)
Net premiums written		1,005,980				146,232				663,594				—				1,815,806
Change in unearned premiums		(122,303		)		(46,459		)		(37,237		)		—				(205,999		)
Net premiums earned		883,677				99,773				626,357				—				1,609,807
Underwriting deductions
Losses and loss expenses		319,298				16,928				251,554				—				587,780
Policy acquisition costs		142,195				10,011				127,092				(3,635		)		275,663
General and administrative expenses		69,649				13,757				100,506				48,423				232,335
Share compensation expenses		5,421				314				6,754				6,994				19,483
Total underwriting deductions		536,563				41,010				485,906				51,782				1,115,261
Underwriting income (loss)		$	347,114			$	58,763			$	140,451			$	(51,782	)		$	494,546
Net investment income		61,770				2,821				13,496				(6,219		)		71,868
Other income (loss)		11,237				17,439				564				(24,943		)		4,297
Finance expenses		(12,133		)		(4,273		)		(256		)		(30,590		)		(47,252		)
Operating income (loss) before taxes, income from operating affiliates and (income) attributable to operating affiliate investors		407,988				74,750				154,255				(113,534		)		523,459
Tax benefit (expense)		1,755				—				(1,184		)		(351		)		220
Income from operating affiliates		—				8,779				—				—				8,779
(Income) attributable to operating affiliate investors		—				(42,156		)		—				—				(42,156		)
Net operating income (loss)		$	409,743			$	41,373			$	153,071			$	(113,885	)		$	490,302
Net realized (losses) gains on investments		(5,790		)		4,084				516				—				(1,190		)
Change in net unrealized losses on investments		(36,883		)		(31,029		)		(10,706		)		—				(78,618		)
Income from investment affiliate		4,274				—				—				—				4,274
Foreign exchange gains (losses)		7,448				(663		)		(1,877		)		(173		)		4,735
Net income (loss)		$	378,792			$	13,765			$	141,004			$	(114,058	)		$	419,503
Net loss attributable to noncontrolling interest		—				17,831				—				—				17,831
Net income (loss) available (attributable) to Validus		$	378,792			$	31,596			$	141,004			$	(114,058	)		$	437,334
Selected ratios (a):
Net premiums written / Gross premiums written		81.6		%		99.6		%		77.6		%						83.9		%
Losses and loss expenses		36.1		%		17		%		40.2		%						36.5		%
Policy acquisition costs		16.1		%		10		%		20.3		%						17.2		%
General and administrative expenses (b)		8.5		%		14.1		%		17.1		%						15.6		%
Expense ratio		24.6		%		24.1		%		37.4		%						32.8		%
Combined ratio		60.7		%		41.1		%		77.6		%						69.3		%
Total assets		$	5,854,354			$	1,446,941			$	2,892,477			$	123,596			$	10,317,368
(a)	Ratios are based on net premiums earned.
(b)	The general and administrative expense ratio includes share compensation expenses.
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:
	Three Months Ended September 30, 2014
	Gross Premiums Written
	Validus Re				AlphaCat				Talbot				Eliminations				Total				%
United States	$	28,665			$	2,206			$	17,003			$	(874	)		$	47,000			13.1	%
Worldwide excluding United States (a)	10,639				(81		)		29,781				(973		)		39,366				10.9	%
Australia and New Zealand	610				—				3,312				(139		)		3,783				1.1	%
Europe	8,560				312				9,821				(311		)		18,382				5.1	%
Latin America and Caribbean	12,945				—				24,740				(819		)		36,866				10.3	%
Japan	1,664				22				1,274				(73		)		2,887				0.8	%
Canada	188				—				2,430				(80		)		2,538				0.7	%
Rest of the world (b)	1,527				—				27,145				(1,073		)		27,599				7.7	%
Sub-total, non United States	36,133				253				98,503				(3,468		)		131,421				36.6	%
Worldwide including United States (a)	28,747				4,477				18,611				(560		)		51,275				14.3	%
Other location non-specific (c)	21,352				—				111,568				(3,642		)		129,278				36	%
Total	$	114,897			$	6,936			$	245,685			$	(8,544	)		$	358,974			100	%
	Three Months Ended September 30, 2013
	Gross Premiums Written
	Validus Re				AlphaCat				Talbot				Eliminations				Total				%
United States	$	38,881			$	2,546			$	21,573			$	(2,105	)		$	60,895			17	%
Worldwide excluding United States (a)	16,973				—				34,751				(4,138		)		47,586				13.3	%
Australia and New Zealand	(9,482		)		33				2,905				(236		)		(6,780		)		(1.9	)%
Europe	4,252				377				9,778				(986		)		13,421				3.8	%
Latin America and Caribbean	5,902				—				38,084				(3,353		)		40,633				11.4	%
Japan	(2,637		)		—				1,066				(117		)		(1,688		)		(0.5	)%
Canada	1,469				500				2,749				(740		)		3,978				1.1	%
Rest of the world (b)	5,641				—				22,167				(1,830		)		25,978				7.3	%
Sub-total, non United States	22,118				910				111,500				(11,400		)		123,128				34.5	%
Worldwide including United States (a)	29,611				25				18,246				(1,665		)		46,217				13	%
Other location non-specific (c)	40,315				—				95,149				(8,944		)		126,520				35.5	%
Total	$	130,925			$	3,481			$	246,468			$	(24,114	)		$	356,760			100	%
	Nine Months Ended September 30, 2014
	Gross Premiums Written
	Validus Re				AlphaCat				Talbot				Eliminations				Total				%
United States	$	452,470			$	31,160			$	85,465			$	(10,662	)		$	558,433			27.5	%
Worldwide excluding United States (a)	80,671				7,331				105,397				(6,741		)		186,658				9.2	%
Australia and New Zealand	20,025				1,019				7,615				(391		)		28,268				1.4	%
Europe	57,884				3,005				36,110				(4,157		)		92,842				4.6	%
Latin America and Caribbean	22,167				—				86,111				(4,418		)		103,860				5.1	%
Japan	41,137				608				3,404				(784		)		44,365				2.2	%
Canada	3,508				215				8,325				(641		)		11,407				0.6	%
Rest of the world (b)	23,870				—				70,702				(3,627		)		90,945				4.5	%
Sub-total, non United States	249,262				12,178				317,664				(20,759		)		558,345				27.6	%
Worldwide including United States (a)	168,337				91,735				71,147				(11,365		)		319,854				15.8	%
Other location non-specific (c)	234,100				—				380,048				(24,141		)		590,007				29.1	%
Total	$	1,104,169			$	135,073			$	854,324			$	(66,927	)		$	2,026,639			100	%
	Nine Months Ended September 30, 2013
	Gross Premiums Written
	Validus Re				AlphaCat				Talbot				Eliminations				Total				%
United States	$	542,692			$	50,935			$	77,630			$	(10,599	)		$	660,658			30.6	%
Worldwide excluding United States (a)	69,482				14,801				109,562				(9,065		)		184,780				8.4	%
Australia and New Zealand	21,116				2,216				7,930				(467		)		30,795				1.4	%
Europe	64,986				2,514				41,523				(3,892		)		105,131				4.9	%
Latin America and Caribbean	5,885				—				124,120				(7,312		)		122,693				5.7	%
Japan	41,939				653				5,258				(963		)		46,887				2.2	%
Canada	4,503				818				8,790				(1,336		)		12,775				0.6	%
Rest of the world (b)	29,211				—				62,803				(3,700		)		88,314				4.1	%
Sub-total, non United States	237,122				21,002				359,986				(26,735		)		591,375				27.3	%
Worldwide including United States (a)	180,621				74,820				63,998				(10,214		)		309,225				14.3	%
Other location non-specific (c)	271,837				—				353,902				(23,164		)		602,575				27.8	%
Total	$	1,232,272			$	146,757			$	855,516			$	(70,712	)		$	2,163,833			100	%
(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, such as marine and aerospace risks, since these exposures can span multiple geographic areas and, in some instances, are not fixed locations.

Subsequent_events

Subsequent events	9 Months Ended
	Sep. 30, 2014
Subsequent Events [Abstract]	'
Subsequent events	'
	Subsequent events
	Western World Insurance Group acquisition
	On June 23, 2014, the Company entered into a stock purchase agreement to acquire all of the issued and outstanding capital stock of Western World Insurance Group, Inc. ("Western World"), a specialty excess and surplus lines insurance company. On October 2, 2014, the Company completed its acquisition of Western World for an aggregate purchase price of $690,000 in cash, subject to adjustment based on pre-closing payments to shareholders, transaction expenses and the timing of closing as further described in the stock purchase agreement. The results of Western World have not been included in the Company’s Consolidated Financial Statements as at September 30, 2014.
	Quarterly Dividend
	On November 5, 2014, the Company announced a quarterly cash dividend of $0.30 per each common share and $0.30 per common share equivalent for which each outstanding warrant is exercisable, payable on December 31, 2014 to holders of record on December 15, 2014.

Significant_accounting_policie

Significant accounting policies (Policies)	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Basis of preparation	'
	These unaudited Consolidated Financial Statements (the "Consolidated Financial Statements") include Validus Holdings, Ltd. and its wholly and majority owned subsidiaries (together the "Company") and 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 the Company's Annual Report on Form 10-K for the year ended December 31, 2013, as filed with the U.S. Securities and Exchange Commission (the "SEC").
	In the opinion of management, these Consolidated Financial Statements reflect all adjustments (including normal recurring adjustments) considered necessary for a fair presentation of the Company's financial position and results of operations as at the end of and for the periods presented. To facilitate comparison of information, certain amounts in prior periods have been reclassified to conform to current period presentation. The consolidated statement of cash flows for the nine months ended September 30, 2013 includes a reclassification of $19,400 that increased net cash flows used in financing activities and net cash flows provided by operating activities to revise the presentation of subscriptions received in advance from third party investors. For the three and nine months ended September 30, 2013, $11,815 and $42,156 respectively, have been reclassified into income attributable to operating affiliate investors from finance expenses to conform to current period presentation. All significant intercompany accounts and transactions have been eliminated.
Use of estimates	'
	The preparation of these 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 management believes that the amounts included in the Consolidated Financial Statements reflect its best estimates and assumptions, actual results could differ materially from those estimates. The Company’s principal estimates include:
	•reserve for losses and loss expenses;
	•premium estimates for business written on a line slip or proportional basis;
	•the valuation of goodwill and intangible assets;
	•reinsurance recoverable balances including the provision for uncollectible amounts; and
	•investment valuation of financial assets.
Reserves for losses and loss expenses	'
	Reserves for losses and loss expenses are based in part upon the estimation of case reserves from broker, insured and ceding company reported data. The Company also uses statistical and actuarial methods to estimate ultimate expected losses and loss expenses, from which incurred but not reported losses can be calculated. The period of time from the occurrence of a loss to the reporting of a loss to the Company and to the settlement of the Company's liability may be several months or years. During this period, additional facts and trends may be revealed. As these factors become apparent, reserves will be adjusted, sometimes requiring an increase or decrease in the overall reserves of the Company, and at other times requiring a reallocation of incurred but not reported reserves to specific case reserves. These estimates are reviewed and adjusted regularly, and such adjustments, if any, are reflected in earnings in the period in which they become known. While management believes that it has made a reasonable estimate of ultimate losses, there can be no assurances that ultimate losses and loss expenses will not exceed this estimate.
Reinsurance	'
	To estimate the provision for uncollectible reinsurance, the reinsurance recoverable is first allocated to applicable reinsurers. This determination is based on a process rather than an estimate, although an element of judgment is applied, especially in relation to ceded IBNR. The Company then uses default factors to determine the portion of a reinsurer’s balance deemed to be uncollectible. Default factors require considerable judgment and are determined in part using the current rating, or rating equivalent, of each reinsurer as well as other key considerations and assumptions.

Investments_Tables

Investments (Tables)	9 Months Ended
	Sep. 30, 2014
Investments [Abstract]	'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'
	The amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments at September 30, 2014 were as follows:
		Amortized Cost or Cost			Gross Unrealized Gains				Gross Unrealized Losses				Estimated Fair Value
	U.S. government and government agency	$	786,318		$	1,735			$	(1,798	)		$	786,255
	Non-U.S. government and government agency	383,378			1,775				(3,956		)		381,197
	U.S. states, municipalities and political subdivisions	73,996			557				(188		)		74,365
	Agency residential mortgage-backed securities	368,646			7,877				(1,296		)		375,227
	Non-agency residential mortgage-backed securities	17,370			238				(409		)		17,199
	U.S. corporate	1,168,304			5,601				(4,987		)		1,168,918
	Non-U.S. corporate	593,619			4,071				(3,055		)		594,635
	Bank loans	488,904			616				(5,732		)		483,788
	Catastrophe bonds	47,574			1,305				(541		)		48,338
	Asset-backed securities	566,135			981				(664		)		566,452
	Commercial mortgage-backed securities	174,341			48				(590		)		173,799
	Total fixed maturities	4,668,585			24,804				(23,216		)		4,670,173
	Total short-term investments (b)	1,684,997			4				(19		)		1,684,982
	Other investments
	Fund of hedge funds	2,802			162				(921		)		2,043
	Hedge funds (a)	570,372			101,610				(104,142		)		567,840
	Private equity investments	11,295			3,832				(108		)		15,019
	Investment funds	123,840			350				—				124,190
	Mutual funds	6,199			3,342				—				9,541
	Total other investments	714,508			109,296				(105,171		)		718,633
	Total investments including noncontrolling interests	$	7,068,090		$	134,104			$	(128,406	)		$	7,073,788
	Noncontrolling interest (a)	$	(502,830	)	$	(86,263	)		$	93,728			$	(495,365	)
	Redeemable noncontrolling interest (b)	$	(11,637	)	$	—			$	—			$	(11,637	)
	Total investments excluding noncontrolling interests	$	6,553,623		$	47,841			$	(34,678	)		$	6,566,786
	(a)	Included in the hedge funds balance are investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.
	(b)	Included in the short-term investments balance are investments held by one AlphaCat ILS fund which is consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
	The amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments at December 31, 2013 were as follows:
		Amortized Cost or Cost			Gross Unrealized Gains				Gross Unrealized Losses				Estimated Fair Value
	U.S. government and government agency	$	1,368,826		$	2,589			$	(6,736	)		$	1,364,679
	Non-U.S. government and government agency	454,578			6,511				(2,021		)		459,068
	U.S. states, municipalities and political subdivisions	42,978			459				(317		)		43,120
	Agency residential mortgage-backed securities	305,450			8,310				(2,261		)		311,499
	Non-agency residential mortgage-backed securities	16,530			143				(914		)		15,759
	U.S. corporate	1,328,960			9,208				(5,684		)		1,332,484
	Non-U.S. corporate	711,581			5,917				(3,173		)		714,325
	Bank loans	712,859			5,659				(1,402		)		717,116
	Catastrophe bonds	72,000			2,551				—				74,551
	Asset-backed securities	509,091			1,409				(843		)		509,657
	Total fixed maturities	5,522,853			42,756				(23,351		)		5,542,258
	Total short-term investments (b)	751,734			45				(1		)		751,778
	Other investments
	Fund of hedge funds	3,141			83				(921		)		2,303
	Hedge funds (a)	584,518			71,641				(95,076		)		561,083
	Private equity investments	12,333			1,410				(258		)		13,485
	Investment funds	31,537			92				—				31,629
	Mutual funds	6,199			3,617				—				9,816
	Total other investments	637,728			76,843				(96,255		)		618,316
	Total investments including noncontrolling interests	$	6,912,315		$	119,644			$	(119,607	)		$	6,912,352
	Noncontrolling interest (a)	(512,121		)	(62,850		)		85,569				(489,402		)
	Redeemable noncontrolling interest (b)	$	(18,365	)	$	—			$	—			$	(18,365	)
	Total investments excluding noncontrolling interests	$	6,381,829		$	56,794			$	(34,038	)		$	6,404,585
	(a)	Included in the hedge funds balance are investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.
	(b)	Included in the short-term investments balance are investments held by two AlphaCat ILS funds which are consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
Investment ratings on fixed maturities	'
	The following table sets forth certain information regarding the investment ratings of the Company’s fixed maturities portfolio as at September 30, 2014 and December 31, 2013.
		September 30, 2014						December 31, 2013
		Estimated Fair Value			% of Total			Estimated Fair Value				% of Total
	AAA	$	2,174,861		46.6	%		$	2,510,781			45.3	%
	AA	594,858			12.7	%		696,998				12.6	%
	A	960,153			20.6	%		1,233,716				22.3	%
	BBB	363,626			7.8	%		323,085				5.8	%
	Total investment-grade fixed maturities	4,093,498			87.7	%		4,764,580				86	%
	BB	283,954			6.1	%		354,992				6.4	%
	B	269,380			5.8	%		383,639				6.9	%
	CCC	1,341			—	%		2,453				—	%
	CC	2,330			—	%		2,496				0.1	%
	C	146			—	%		235				—	%
	D/NR	19,524			0.4	%		33,863				0.6	%
	Total non-investment grade fixed maturities	576,675			12.3	%		777,678				14	%
	Total fixed maturities	$	4,670,173		100	%		$	5,542,258			100	%
Fixed maturities investments by contractual maturity	'
	The amortized cost and estimated fair value amounts for fixed maturities held at September 30, 2014 and December 31, 2013 are shown below by contractual maturity. Actual maturity may differ from contractual maturity because certain borrowers may have the right to call or prepay certain obligations with or without call or prepayment penalties.
		September 30, 2014							December 31, 2013
		Amortized Cost			Estimated Fair Value				Amortized Cost				Estimated Fair Value
	Due in one year or less	$	277,213		$	278,507			$	688,855			$	692,768
	Due after one year through five years	2,678,792			2,679,938				3,603,459				3,613,847
	Due after five years through ten years	496,922			491,364				396,389				395,633
	Due after ten years	89,166			87,687				3,079				3,095
		3,542,093			3,537,496				4,691,782				4,705,343
	Asset-backed and mortgage-backed securities	1,126,492			1,132,677				831,071				836,915
	Total fixed maturities	$	4,668,585		$	4,670,173			$	5,522,853			$	5,542,258
Net investment income	'
	Net investment income was derived from the following sources:
		Three Months Ended							Nine Months Ended
		September 30, 2014			September 30, 2013				September 30, 2014				September 30, 2013
	Fixed maturities and short-term investments	$	22,544		$	20,936			$	68,048			$	74,618
	Other investments	2,879			—				2,879				—
	Cash and cash equivalents	1,581			1,079				4,534				3,241
	Securities lending income	1			3				5				3
	Total gross investment income	27,005			22,018				75,466				77,862
	Investment expenses	(1,744		)	(2,009		)		(5,557		)		(5,994		)
	Total net investment income	$	25,261		$	20,009			$	69,909			$	71,868
Analysis of net realized gains (losses) and the change in net unrealized (losses) gains on investments	'
	The following represents an analysis of net realized gains (losses) and the change in net unrealized (losses) gains on investments:
		Three Months Ended							Nine Months Ended
		September 30, 2014			September 30, 2013				September 30, 2014				September 30, 2013
	Fixed maturities, short-term and other investments
	Gross realized gains (a)	$	8,075		$	7,706			$	23,184			$	25,578
	Gross realized (losses)	(3,480		)	(14,026		)		(6,991		)		(26,768		)
	Net realized gains (losses) on investments	4,595			(6,320		)		16,193				(1,190		)
	Change in net unrealized (losses) gains on investments (a)	(84,974		)	69,967				16,146				(78,618		)
	Total net realized gains (losses) and change in net unrealized (losses) gains on investments including noncontrolling interest	(80,379		)	63,647				32,339				(79,808		)
	Noncontrolling interest (a)	52,595			(42,579		)		(22,613		)		25,766
	Total net realized gains (losses) and change in net unrealized (losses) gains on investments excluding noncontrolling interest	$	(27,784	)	$	21,068			$	9,726			$	(54,042	)
	(a)	Includes change in net unrealized gains (losses) and realized gains on investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and is included in the Consolidated Statements of Comprehensive Income as net loss (income) attributable to noncontrolling interest.
Investments pledged as collateral under credit facilities	'
	The following tables outline investments pledged as collateral under the Company's credit facilities. For further details on the credit facilities, please refer to Note 12: “Debt and financing arrangements.”
			September 30, 2014
	Description		Commitment			Issued and Outstanding				Investments and cash pledged as collateral
	$400,000 syndicated unsecured letter of credit facility		$	400,000		$	—			$	—
	$525,000 syndicated secured letter of credit facility		525,000			301,340				393,720
	$200,000 secured bi-lateral letter of credit facility		200,000			19,743				35,414
	Talbot FAL facility		25,000			25,000				31,054
	PaCRe senior secured letter of credit facility		10,000			294				—
	AlphaCat Re secured letter of credit facility		30,000			30,000				30,059
	IPC bi-lateral facility		40,000			16,975				96,633
	$375,000 Flagstone bi-lateral facility		375,000			288,739				456,458
	Total		$	1,605,000		$	682,091			$	1,043,338
			December 31, 2013
	Description		Commitment			Issued and Outstanding				Investments and cash pledged as collateral
	$400,000 syndicated unsecured letter of credit facility		$	400,000		$	—			$	—
	$525,000 syndicated secured letter of credit facility		525,000			358,567				507,620
	$200,000 secured bi-lateral letter of credit facility		200,000			16,726				130,256
	Talbot FAL facility		25,000			25,000				30,801
	PaCRe senior secured letter of credit facility		10,000			294				—
	AlphaCat Re secured letter of credit facility		24,800			24,800				24,806
	IPC bi-lateral facility		40,000			20,177				98,465
	$375,000 Flagstone bi-lateral facility		375,000			305,686				454,458
	Total		$	1,599,800		$	751,250			$	1,246,406

Fair_value_measurements_Tables

Fair value measurements (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair value hierarchy - allocation of investments	'
	At September 30, 2014, the Company’s investments were allocated between Levels 1, 2 and 3 as follows:
		Level 1			Level 2			Level 3			Total
	U.S. government and government agency	$	—		$	786,255		$	—		$	786,255
	Non-U.S. government and government agency	—			381,197			—			381,197
	U.S. states, municipalities and political subdivisions	—			74,365			—			74,365
	Agency residential mortgage-backed securities	—			375,227			—			375,227
	Non-agency residential mortgage-backed securities	—			17,199			—			17,199
	U.S. corporate	—			1,168,918			—			1,168,918
	Non-U.S. corporate	—			594,635			—			594,635
	Bank loans	—			483,788			—			483,788
	Catastrophe bonds	—			43,337			5,001			48,338
	Asset-backed securities	—			566,452			—			566,452
	Commercial mortgage-backed securities	—			173,799			—			173,799
	Total fixed maturities	—			4,665,172			5,001			4,670,173
	Total short-term investments (b)	1,671,911			13,071			—			1,684,982
	Other investments
	Fund of hedge funds	—			—			2,043			2,043
	Hedge funds (a)	—			—			567,840			567,840
	Private equity investments	—			—			15,019			15,019
	Investment funds	—			21,310			102,880			124,190
	Mutual funds	—			9,541			—			9,541
	Total other investments	—			30,851			687,782			718,633
	Total investments including noncontrolling interests	$	1,671,911		$	4,709,094		$	692,783		$	7,073,788
	Noncontrolling interest (a)	$	—		$	—		$	(495,365	)	$	(495,365	)
	Redeemable noncontrolling interest (b)	$	(11,637	)	$	—		$	—		$	(11,637	)
	Total investments excluding noncontrolling interests	$	1,660,274		$	4,709,094		$	197,418		$	6,566,786
	(a)	Included in the hedge funds balance are investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.
	(b)	Included in the short-term investments balance are investments held by one AlphaCat ILS fund which is consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
	At December 31, 2013, the Company’s investments were allocated between Levels 1, 2 and 3 as follows:
		Level 1			Level 2			Level 3			Total
	U.S. government and government agency	$	—		$	1,364,679		$	—		$	1,364,679
	Non-U.S. government and government agency	—			459,068			—			459,068
	U.S. states, municipalities and political subdivisions	—			43,120			—			43,120
	Agency residential mortgage-backed securities	—			311,499			—			311,499
	Non-agency residential mortgage-backed securities	—			15,759			—			15,759
	U.S. corporate	—			1,332,484			—			1,332,484
	Non-U.S. corporate	—			714,325			—			714,325
	Bank loans	—			717,116			—			717,116
	Catastrophe bonds	—			74,551			—			74,551
	Asset-backed securities	—			509,657			—			509,657
	Total fixed maturities	—			5,542,258			—			5,542,258
	Total short-term investments (b)	747,215			4,563			—			751,778
	Other investments
	Fund of hedge funds	—			—			2,303			2,303
	Hedge funds (a)	—			—			561,083			561,083
	Private equity investments	—			—			13,485			13,485
	Investment fund	—			31,629			—			31,629
	Mutual funds	—			9,816			—			9,816
	Total other investments	—			41,445			576,871			618,316
	Total investments including noncontrolling interests	$	747,215		$	5,588,266		$	576,871		$	6,912,352
	Noncontrolling interest (a)	$	—		$	—		$	(489,402	)	$	(489,402	)
	Redeemable noncontrolling interest (b)	$	(18,365	)	$	—		$	—		$	(18,365	)
	Total investments excluding noncontrolling interests	$	728,850		$	5,588,266		$	87,469		$	6,404,585
	(a)	Included in the hedge funds balance are investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.
	(b)	Included in the short-term investments balance are investments held by two AlphaCat ILS funds which are consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
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 nine months ended September 30, 2014 and 2013:
		Three Months Ended						Nine Months Ended
		30-Sep-14			30-Sep-13			30-Sep-14			30-Sep-13
	Level 3 investments - Beginning of period	$	746,396		$	505,158		$	576,871		$	556,234
	Purchases	25,784			33,154			125,784			98,669
	Sales	(24,175		)	(35,264		)	(49,508		)	(80,095		)
	Settlements	—			—			(1,500		)	—
	Net realized gains	2,554			4,503			8,198			4,843
	Change in net unrealized gains (losses)	(57,776		)	42,917			26,235			(29,183		)
	Transfers into Level 3	—			—			6,703			—
	Level 3 investments - End of period	$	692,783		$	550,468		$	692,783		$	550,468
	Noncontrolling interest (a)	(495,365		)	(465,472		)	(495,365		)	(465,472		)
	Level 3 investments excluding noncontrolling interest	$	197,418		$	84,996		$	197,418		$	84,996
	(a)	Includes Level 3 investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.

Investments_in_affiliates_Tabl

Investments in affiliates (Tables)	9 Months Ended
	Sep. 30, 2014
Schedule of Equity Method Investments [Line Items]	'
Schedule of equity method investments	'
	The following table presents the Company's investments in affiliates as at September 30, 2014 and December 31, 2013:
		30-Sep-14			31-Dec-13
	Investment affiliate	$	42,381		$	34,500
	Operating affiliates	175,231			106,743
	Investments in affiliates	$	217,612		$	141,243
Summary of notes payable to operating affiliates	'
	The following tables present a reconciliation of the beginning and ending notes payable to operating affiliates for the three and nine months ended September 30, 2014 and 2013:
		Three Months Ended September 30, 2014
		AlphaCat 2013			AlphaCat 2014				AlphaCat ILS funds				Total
	As at June 30, 2014	$	—		$	157,992			$	464,958			$	622,950
	Issuance of notes payable to operating affiliates	—			—				53,498				53,498
	Redemption of notes payable to operating affiliates	—			—				(13,990		)		(13,990		)
	Foreign exchange gain	—			(410		)		(6,072		)		(6,482		)
	As at September 30, 2014	$	—		$	157,582			$	498,394			$	655,976
		Three Months Ended September 30, 2013
		AlphaCat 2013			AlphaCat ILS funds				Total
	As at June 30, 2013	$	222,135		$	208,958			$	431,093
	Issuance of notes payable to operating affiliates	—			6,733				6,733
	Redemption of notes payable to operating affiliates	—			(3,553		)		(3,553		)
	Foreign exchange loss	1,196			2,501				3,697
	As at September 30, 2013	$	223,331		$	214,639			$	437,970
		Nine Months Ended September 30, 2014
		AlphaCat 2013			AlphaCat 2014				AlphaCat ILS funds				Total
	As at December 31, 2013	$	223,809		$	—			$	215,463			$	439,272
	Notes payable to operating affiliates recognized on deconsolidation of AlphaCat ILS fund	—			—				178,837				178,837
	Issuance of notes payable to operating affiliates	—			157,914				487,329				645,243
	Redemption of notes payable to operating affiliates	(223,512		)	—				(378,556		)		(602,068		)
	Foreign exchange gain	(297		)	(332		)		(4,679		)		(5,308		)
	As at September 30, 2014	$	—		$	157,582			$	498,394			$	655,976
		Nine Months Ended September 30, 2013
		AlphaCat 2013			AlphaCat ILS funds				Total
	As at December 31, 2012	$	—		$	—			$	—
	Issuance of notes payable to operating affiliates	223,082			218,044				441,126
	Redemption of notes payable to operating affiliates	—			(3,553		)		(3,553		)
	Foreign exchange loss	249			148				397
	As at September 30, 2013	$	223,331		$	214,639			$	437,970
Schedule of (income) attributable to operating affiliate investors	'
	The following table presents the (income) attributable to operating affiliate investors for the three and nine months ended September 30, 2014 and 2013:
		Three Months Ended							Nine Months Ended
		September 30,			September 30,				September 30,				September 30,
		2014			2013				2014				2013
	AlphaCat 2013	$	(98	)	$	(4,074	)		$	(14,218	)		$	(29,357	)
	AlphaCat 2014	(11,309		)	—				(32,990		)		—
	AlphaCat ILS funds	(14,400		)	(7,741		)		(35,625		)		(12,799		)
	(Income) attributable to operating affiliate investors	$	(25,807	)	$	(11,815	)		$	(82,833	)		$	(42,156	)
Investment affiliate	'
Schedule of Equity Method Investments [Line Items]	'
Reconciliation of the beginning and ending non-consolidated affiliate balance	'
	The following table presents a reconciliation of the beginning and ending investment in the Company's investment affiliate balance for the three and nine months ended September 30, 2014 and 2013:
		Three Months Ended							Nine Months Ended
		September 30,			September 30,				September 30,				September 30,
		2014			2013				2014				2013
	Investment affiliate, beginning of period	$	40,627		$	25,352			$	34,500			$	15,218
	Capital contributions	—			6,185				—				13,089
	Income from investment affiliate	1,754			1,044				7,881				4,274
	Investment affiliate, end of period	$	42,381		$	32,581			$	42,381			$	32,581
Schedule of equity method investments	'
	The following table presents the Company's investment in the Partnership as at September 30, 2014:
		Investment in investment affiliate
		Investment at cost			Voting ownership %			Equity Ownership			Carrying Value
	Aquiline Financial Services Fund II L.P.	$	32,110		—	%		6.7	%		$	42,381
	The following table presents the Company's investment in the Partnership as at December 31, 2013:
		Investment in investment affiliate
		Investment at cost			Voting ownership %			Equity Ownership			Carrying Value
	Aquiline Financial Services Fund II L.P.	$	32,110		—	%		6.7	%		$	34,500
Operating affiliates	'
Schedule of Equity Method Investments [Line Items]	'
Reconciliation of the beginning and ending non-consolidated affiliate balance	'
	The following tables present a reconciliation of the beginning and ending investment in operating affiliates for the three and nine months ended September 30, 2014 and 2013:
		Three Months Ended September 30, 2014
		AlphaCat Re 2011			AlphaCat Re 2012				AlphaCat 2013				AlphaCat 2014			AlphaCat ILS funds			Total
	As at June 30, 2014	$	4,172		$	2,204			$	2,580			$	25,014		$	139,022		$	172,992
	Return of investment	—			(1,516		)		(6		)		—			—			(1,522		)
	(Loss) income from operating affiliates	(5		)	(9		)		7				1,367			2,401			3,761
	As at September 30, 2014	$	4,167		$	679			$	2,581			$	26,381		$	141,423		$	175,231
		Three Months Ended September 30, 2013
		AlphaCat Re 2011			AlphaCat Re 2012				AlphaCat 2013				AlphaCat ILS fund			Total
	As at June 30, 2013	$	11,054		$	5,204			$	48,536			$	20,326		$	85,120
	Return of investment	(2,800		)	(4,550		)		—				—			(7,350		)
	(Loss) income from operating affiliates	(270		)	(7		)		585				1,155			1,463
	As at September 30, 2013	$	7,984		$	647			$	49,121			$	21,481		$	79,233
		Nine Months Ended September 30, 2014
		AlphaCat Re 2011			AlphaCat Re 2012				AlphaCat 2013				AlphaCat 2014			AlphaCat ILS funds			Total
	As at December 31, 2013	$	9,809		$	1,313			$	51,744			$	21,982		$	21,895		$	106,743
	Return of investment	(5,825		)	(1,516		)		(51,206		)		—			—			(58,547		)
	Fair value of retained interest on deconsolidation of AlphaCat ILS fund	—			—				—				—			113,455			113,455
	Income from operating affiliates	183			882				2,043				4,399			6,073			13,580
	As at September 30, 2014	$	4,167		$	679			$	2,581			$	26,381		$	141,423		$	175,231
		Nine Months Ended September 30, 2013
		AlphaCat Re 2011			AlphaCat Re 2012				AlphaCat 2013				AlphaCat ILS fund			Total
	As at December 31, 2012	$	62,792		$	29,319			$	45,000			$	20,000		$	157,111
	Return of investment	(54,914		)	(31,743		)		—				—			(86,657		)
	Income from operating affiliates	106			3,071				4,121				1,481			8,779
	As at September 30, 2013	$	7,984		$	647			$	49,121			$	21,481		$	79,233
Schedule of equity method investments	'
	The following table presents the Company's investments in AlphaCat Re 2011, AlphaCat Re 2012, AlphaCat 2013, AlphaCat 2014 and the AlphaCat ILS funds in the Consolidated Financial Statements as at September 30, 2014:
		Investment in operating affiliates
		Cost			Voting ownership %			Equity ownership %			Carrying value
	AlphaCat Re 2011	$	4,167		43.7	%		22.3	%		$	4,167
	AlphaCat Re 2012	679			49	%		37.9	%		679
	AlphaCat 2013	2,581			40.9	%		19.7	%		2,581
	AlphaCat 2014	22,000			42.3	%		19.6	%		26,381
	AlphaCat ILS funds	133,455			n/a			(a)			141,423
	Total	$	162,882								$	175,231
	(a)	Equity ownership in the two funds were 7.9% and 49.0% respectively as at September 30, 2014.
	The following table presents the Company's investments in AlphaCat Re 2011, AlphaCat Re 2012, AlphaCat 2013, AlphaCat 2014 and the AlphaCat ILS fund in the Consolidated Financial Statements as at December 31, 2013:
		Investment in operating affiliates
		Cost			Voting ownership %			Equity ownership %			Carrying value
	AlphaCat Re 2011	$	9,882		43.7	%		22.3	%		$	9,809
	AlphaCat Re 2012	654			49	%		37.9	%		1,313
	AlphaCat 2013	45,000			40.9	%		19.7	%		51,744
	AlphaCat 2014	22,000			42.3	%		19.6	%		21,982
	AlphaCat ILS fund	20,000			n/a			9.1	%		21,895
	Total	$	97,536								$	106,743

Noncontrolling_interest_Tables

Noncontrolling interest (Tables)	9 Months Ended
	Sep. 30, 2014
Noncontrolling Interest [Abstract]	'
Noncontrolling interest	'
	The following tables present a reconciliation of the beginning and ending balances of redeemable noncontrolling interest and noncontrolling interest for the three and nine months ended September 30, 2014 and 2013:
		Three Months Ended September 30, 2014
		Redeemable noncontrolling interest			Noncontrolling interest			Total
	As at June 30, 2014	$	66,282		$	575,347		$	641,629
	Issuance of shares	4,200			—			4,200
	Loss attributable to noncontrolling interest	(9		)	(53,060		)	(53,069		)
	As at September 30, 2014	$	70,473		$	522,287		$	592,760
		Three Months Ended September 30, 2013
		Redeemable noncontrolling interest			Noncontrolling interest			Total
	As at June 30, 2013	$	70,690		$	427,755		$	498,445
	Issuance of shares	13,000			—			13,000
	Income attributable to noncontrolling interest	1,516			44,178			45,694
	Redemption of shares	(10,207		)	—			(10,207		)
	As at September 30, 2013	$	74,999		$	471,933		$	546,932
		Nine Months Ended September 30, 2014
		Redeemable noncontrolling interest			Noncontrolling interest			Total
	As at December 31, 2013	$	86,512		$	497,657		$	584,169
	Issuance of shares	61,200			—			61,200
	Income attributable to noncontrolling interest	1,115			24,630			25,745
	Adjustment to noncontrolling interest as a result of deconsolidation	(78,354		)	—			(78,354		)
	As at September 30, 2014	$	70,473		$	522,287		$	592,760
		Nine Months Ended September 30, 2013
		Redeemable noncontrolling interest			Noncontrolling interest			Total
	As at December 31, 2012	$	—		$	434,280		$	434,280
	Issuance of shares	82,190			58,500			140,690
	Income (loss) attributable to noncontrolling interest	3,016			(20,847		)	(17,831		)
	Redemption of shares	(10,207		)	—			(10,207		)
	As at September 30, 2013	$	74,999		$	471,933		$	546,932

Derivative_instruments_Tables

Derivative instruments (Tables)	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
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 at September 30, 2014 and December 31, 2013:
			As at September 30, 2014									As at December 31, 2013
	Derivatives designated as hedging instruments:		Net Notional Exposure			Asset Derivative at Fair Value (a)			Liability Derivative at Fair Value (a)			Net Notional Exposure			Asset Derivative at Fair Value (a)		Liability Derivative at Fair Value (a)
	Foreign currency forward contracts		$	246,638		$	592		$	16,672		$	163,576		$	1,167	$	2,313
	Interest rate swap contracts		$	552,263		$	25		$	912		$	552,263		$	28	$	911
	(a)	Asset and liability derivatives are classified within other assets and accounts payable and accrued expenses respectively on the Consolidated Balance Sheets.
Derivative instruments designated as a fair value hedge	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Location and amount of gains and losses related to derivative instruments reported on in the income statement	'
	The following table provides the total impact on earnings, recognized in income within foreign exchange gains (losses), relating to the derivative instruments formally designated as fair value hedges along with the impact of the related hedged items for the three and nine months ended September 30, 2014 and 2013:
			Three Months Ended						Nine Months Ended
	Foreign currency forward contracts		September 30, 2014			September 30, 2013			September 30, 2014			September 30, 2013
	Amount of (loss) gain recognized in income on derivative		$	(14,817	)	$	3,116		$	(9,979	)	$	2,670
	Amount of gain (loss) on hedged item recognized in income attributable to risk being hedged		$	14,817		$	(3,116	)	$	9,979		$	(2,670	)
	Amount of gain (loss) recognized in income on derivative (ineffective portion)		$	—		$	—		$	—		$	—
Derivative instruments designated as a cash flow hedge	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Location and amount of gains and losses related to derivative instruments reported on in the income statement	'
	The following table provides the total impact on other comprehensive income (loss) and earnings relating to the derivative instruments formally designated as cash flow hedges along with the impact of the related hedged items for the three and nine months ended September 30, 2014 and 2013:
			Three Months Ended						Nine Months Ended
	Interest rate swap contracts		September 30, 2014			September 30, 2013			September 30, 2014			September 30, 2013
	Amount of effective portion recognized in other comprehensive income		$	3,302		$	3,268		$	9,762		$	7,838
	Amount of effective portion subsequently reclassified to earnings		$	(3,302	)	$	(3,268	)	$	(9,762	)	$	(7,838	)
	Amount of ineffective portion excluded from effectiveness testing		$	—		$	—		$	—		$	—

Reserve_for_losses_and_loss_ex1

Reserve for losses and loss expenses (Tables)	9 Months Ended
	Sep. 30, 2014
Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract]	'
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 nine months ended September 30, 2014 and 2013:
		Three Months Ended						Nine Months Ended
		September 30,			September 30,			September 30,			September 30,
		2014			2013			2014			2013
	Reserve for losses and loss expenses, beginning of period	$	2,867,307		$	3,283,450		$	3,030,399		$	3,517,573
	Losses and loss expenses recoverable	(338,734		)	(418,693		)	(370,154		)	(439,967		)
	Net reserves for losses and loss expenses, beginning of period	2,528,573			2,864,757			2,660,245			3,077,606
	Net reserves disposed	—			—			—			(18,591		)
	Increase (decrease) in net reserves for losses and loss expenses in respect of losses occurring in:
	Current year	279,690			243,015			713,177			759,617
	Prior years	(55,565		)	(65,050		)	(167,636		)	(171,837		)
	Total incurred losses and loss expenses	224,125			177,965			545,541			587,780
	Less net losses and loss expenses paid in respect of losses occurring in:
	Current year	(74,618		)	(59,701		)	(99,326		)	(95,535		)
	Prior years	(183,697		)	(215,167		)	(633,048		)	(732,118		)
	Total net paid losses	(258,315		)	(274,868		)	(732,374		)	(827,653		)
	Foreign exchange	(40,717		)	34,363			(19,746		)	(16,925		)
	Net reserve for losses and loss expenses, end of period	2,453,666			2,802,217			2,453,666			2,802,217
	Losses and loss expenses recoverable	298,502			421,518			298,502			421,518
	Reserve for losses and loss expenses, end of period	$	2,752,168		$	3,223,735		$	2,752,168		$	3,223,735
	Incurred losses and loss expenses comprise:
		Three Months Ended						Nine Months Ended
		September 30,			September 30,			September 30,			September 30,
		2014			2013			2014			2013
	Gross losses and loss expenses	$	222,356		$	226,130		$	587,111		$	684,080
	Reinsurance recoverable	1,769			(48,165		)	(41,570		)	(96,300		)
	Net incurred losses and loss expenses	$	224,125		$	177,965		$	545,541		$	587,780

Reinsurance_Tables

Reinsurance (Tables)	9 Months Ended
	Sep. 30, 2014
Reinsurance Disclosures [Abstract]	'
Reinsurance recoverables by reinsurer	'
	Reinsurance recoverables by reinsurer as at September 30, 2014 and December 31, 2013 are as follows:
		September 30, 2014					December 31, 2013
		Reinsurance Recoverable			% of Total		Reinsurance Recoverable		% of Total
	Top 10 reinsurers	$	264,131		73.1	%	$	340,253	75.6	%
	Other reinsurers’ balances > $1 million	89,584			24.8	%	100,784		22.4	%
	Other reinsurers’ balances < $1 million	7,778			2.1	%	9,197		2	%
	Total	$	361,493		100	%	$	450,234	100	%
			September 30, 2014
	Top 10 Reinsurers		Rating	Reinsurance Recoverable			% of Total
	Lloyd's Syndicates		A+	$	60,218		16.7	%
	Everest Re		A+	46,765			12.9	%
	Third Point Re		A-	34,180			9.5	%
	Fully Collateralized		NR	33,770			9.3	%
	Hannover Re		AA-	33,124			9.2	%
	Swiss Re		AA-	13,849			3.8	%
	Transatlantic Re		A+	11,649			3.2	%
	XL Re		A+	10,334			2.9	%
	Munich Re		AA-	10,232			2.8	%
	Aioi Nissay Dowa Insurance		A+	10,010			2.8	%
	Total			$	264,131		73.1	%
	NR: Not rated
			December 31, 2013
	Top 10 Reinsurers		Rating	Reinsurance Recoverable			% of Total
	Lloyd's Syndicates		A+	$	73,398		16.3	%
	National Indemnity		AA+	51,037			11.3	%
	Everest Re		A+	48,055			10.7	%
	Hannover Re		AA-	41,483			9.2	%
	Fully Collateralized		NR	36,683			8.1	%
	Third Point Re		A-	30,428			6.8	%
	Swiss Re		AA-	20,022			4.5	%
	Transatlantic Re		A+	14,114			3.1	%
	XL Re		A+	12,673			2.8	%
	Munich Re		AA-	12,360			2.8	%
	Total			$	340,253		75.6	%
	NR: Not rated

Share_capital_Tables

Share capital (Tables)	9 Months Ended
	Sep. 30, 2014
Stockholders' Equity Note [Abstract]	'
Summary of common shares issued and outstanding	'
	The following table is a summary of the common shares issued and outstanding:
		Common Shares
	Common shares issued, December 31, 2013	154,488,497
	Restricted share awards vested, net of shares withheld	594,582
	Restricted share units vested, net of shares withheld	10,265
	Options exercised	133,385
	Direct issuance of common stock	1,060
	Performance share awards vested, net of shares withheld	25,767
	Common shares issued, September 30, 2014	155,253,556
	Treasury shares, September 30, 2014	(66,141,285	)
	Common shares outstanding, September 30, 2014	89,112,271
		Common Shares
	Common shares issued, December 31, 2012	152,698,191
	Restricted share awards vested, net of shares withheld	768,889
	Restricted share units vested, net of shares withheld	14,381
	Options exercised	277,615
	Warrants exercised	591,480
	Direct issuance of common stock	928
	Performance share awards vested, net of shares withheld	31,897
	Deferred share units vested, net of shares withheld	2,935
	Common shares issued, September 30, 2013	154,386,316
	Treasury shares, September 30, 2013	(54,488,320	)
	Common shares outstanding, September 30, 2013	99,897,996

Stock_plans_Tables

Stock plans (Tables)	9 Months Ended
	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Options, activity during the period	'
	Activity with respect to options for the nine months ended September 30, 2014 was as follows:
		Options		Weighted Average Grant Date Fair Value			Weighted Average Grant Date Exercise Price
	Options outstanding, December 31, 2013	1,572,713		$	6.66		$	18.88
	Options exercised	(133,385	)	3.81			25.1
	Options outstanding, September 30, 2014	1,439,328		$	6.93		$	18.3
	Activity with respect to options for the nine months ended September 30, 2013 was as follows:
		Options		Weighted Average Grant Date Fair Value			Weighted Average Grant Date Exercise Price
	Options outstanding, December 31, 2012	1,823,947		$	6.52		$	20.69
	Options regranted (modified)	1,833,414		6.76			19.02
	Options exercised	(277,615	)	5.24			23.58
	Options cancelled (modified)	(1,733,139	)	6.76			20.12
	Options outstanding, September 30, 2013	1,646,607		$	6.75		$	18.94
Restricted shares awards, activity during the period	'
	Activity with respect to unvested restricted share awards for the nine months ended September 30, 2014 was as follows:
		Restricted Share Awards		Weighted Average Grant Date Fair Value
	Restricted share awards outstanding, December 31, 2013	2,684,745		$	33.74
	Restricted share awards granted	925,610		37.33
	Restricted share awards vested	(769,971	)	31.47
	Restricted share awards forfeited	(69,117	)	36.28
	Restricted share awards outstanding, September 30, 2014	2,771,267		$	35.5
	Activity with respect to unvested restricted share awards for the nine months ended September 30, 2013 was as follows:
		Restricted Share Awards		Weighted Average Grant Date Fair Value
	Restricted share awards outstanding, December 31, 2012	2,170,547		$	29.24
	Restricted share awards granted	1,580,117		36.06
	Restricted share awards vested	(930,296	)	28.08
	Restricted share awards forfeited	(110,912	)	28.34
	Restricted share awards outstanding, September 30, 2013	2,709,456		$	33.65
Restricted share units, activity during the period	'
	Activity with respect to unvested restricted share units for the nine months ended September 30, 2014 was as follows:
		Restricted Share Units		Weighted Average Grant Date Fair Value
	Restricted share units outstanding, December 31, 2013	66,518		$	33.74
	Restricted share units granted	53,025		38.1
	Restricted share units vested	(18,325	)	30.71
	Restricted share units issued in lieu of cash dividends	1,479		34.19
	Restricted share units outstanding, September 30, 2014	102,697		$	36.54
	Activity with respect to unvested restricted share units for the nine months ended September 30, 2013 was as follows:
		Restricted Share Units		Weighted Average Grant Date Fair Value
	Restricted share units outstanding, December 31, 2012	47,238		$	29.61
	Restricted share units granted	36,635		36.11
	Restricted share units vested	(21,814	)	28.17
	Restricted share units issued in lieu of cash dividends	3,924		30.29
	Restricted share units outstanding, September 30, 2013	65,983		$	33.74
Performance share awards, activity during the period	'
	Activity with respect to unvested performance share awards for the nine months ended September 30, 2014 was as follows:
		Performance Share Awards		Weighted Average Grant Date Fair Value
	Performance share awards outstanding, December 31, 2013	101,820		$	33.56
	Performance share awards granted	52,639		37.33
	Performance share awards vested	(32,746	)	32.62
	Performance share awards conversion adjustment	(15,344	)	31.38
	Performance share awards outstanding, September 30, 2014	106,369		$	36.03
	Activity with respect to unvested performance share awards for the nine months ended September 30, 2013 was as follows:
		Performance Share Awards		Weighted Average Grant Date Fair Value
	Performance share awards outstanding, December 31, 2012	220,845		$	31.81
	Performance share awards granted	38,386		36.11
	Performance share awards vested	(39,094	)	28.7
	Performance share awards forfeited	(18,701	)	31.05
	Performance share awards conversion adjustment	(99,616	)	$	33.05
	Performance share awards outstanding, September 30, 2013	101,820		$	33.56
Total share compensation expenses	'
	The breakdown of share compensation expenses by award type was as follows:
		Three Months Ended						Nine Months Ended
		September 30,			September 30,			September 30,		September 30,
		2014			2013			2014		2013
	Restricted share awards	8,180			10,041			23,101		20,035
	Restricted share units	269			168			602		419
	Performance share awards	315			318			549		(971		)
	Total	$	8,764		$	10,527		$	24,252	$	19,483

Debt_and_financing_arrangement1

Debt and financing arrangements (Tables)	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Schedule of financing structure	'
	The financing structure at September 30, 2014 was:
		Commitment			Issued and outstanding (a)				Drawn
	2006 Junior Subordinated Deferrable Debentures	$	150,000		$	150,000			$	150,000
	2007 Junior Subordinated Deferrable Debentures	200,000			139,800				139,800
	Flagstone 2006 Junior Subordinated Deferrable Debentures	136,403			136,403				136,403
	Flagstone 2007 Junior Subordinated Deferrable Debentures	113,750			113,750				113,750
	Total debentures payable	600,153			539,953				539,953
	2010 Senior Notes due 2040	250,000			250,000				247,279
	Total debentures and senior notes payable	850,153			789,953				787,232
	$400,000 syndicated unsecured letter of credit facility	400,000			—				—
	$525,000 syndicated secured letter of credit facility	525,000			301,340				—
	$200,000 secured bi-lateral letter of credit facility	200,000			19,743				—
	Talbot FAL facility	25,000			25,000				—
	PaCRe senior secured letter of credit facility	10,000			294				—
	AlphaCat Re secured letter of credit facility	30,000			30,000				—
	IPC bi-lateral facility	40,000			16,975				—
	$375,000 Flagstone bi-lateral facility	375,000			288,739				—
	Total credit and other facilities	1,605,000			682,091				—
	Total debt and financing arrangements	$	2,455,153		$	1,472,044			$	787,232
	The financing structure at December 31, 2013 was:
		Commitment			Issued and outstanding (a)				Drawn
	2006 Junior Subordinated Deferrable Debentures	$	150,000		$	150,000			$	150,000
	2007 Junior Subordinated Deferrable Debentures	200,000			139,800				139,800
	Flagstone 2006 Junior Subordinated Deferrable Debentures	137,866			137,866				137,866
	Flagstone 2007 Junior Subordinated Deferrable Debentures	113,750			113,750				113,750
	Total debentures payable	601,616			541,416				541,416
	2010 Senior Notes due 2040	250,000			250,000				247,198
	Total debentures and senior notes payable	851,616			791,416				788,614
	$400,000 syndicated unsecured letter of credit facility	400,000			—				—
	$525,000 syndicated secured letter of credit facility	525,000			358,567				—
	$200,000 secured bi-lateral letter of credit facility	200,000			16,726				—
	Talbot FAL facility	25,000			25,000				—
	PaCRe senior secured letter of credit facility	10,000			294				—
	AlphaCat Re secured letter of credit facility	24,800			24,800				—
	IPC bi-lateral facility	40,000			20,177				—
	$375,000 Flagstone bi-lateral facility	375,000			305,686				—
	Total credit and other facilities	1,599,800			751,250				—
	Total debt and financing arrangements	$	2,451,416		$	1,542,666			$	788,614
	(a)	Indicates utilization of commitment amount, not necessarily drawn borrowings.
Debt Instruments [Line Items]	'
Components of finance expenses	'
	Finance expenses consist of interest on the junior subordinated deferrable debentures and senior notes, the amortization of debt offering costs, credit facilities fees, bank charges, AlphaCat financing fees and Talbot FAL costs as follows:
		Three Months Ended							Nine Months Ended
		September 30,			September 30,				September 30,			September 30,
		2014			2013				2014			2013
	2006 Junior Subordinated Deferrable Debentures	$	2,235		$	2,235			$	6,633		$	6,633
	2007 Junior Subordinated Deferrable Debentures	1,848			1,848				5,492			5,492
	Flagstone 2006 Junior Subordinated Deferrable Debentures	2,269			2,285				6,736			5,988
	Flagstone 2007 Junior Subordinated Deferrable Debentures	1,807			1,807				5,335			4,426
	2010 Senior Notes due 2040	5,597			5,597				16,791			16,791
	Credit facilities	1,295			1,248				4,225			5,001
	Bank charges	88			187				303			420
	AlphaCat ILS funds fees (a)	384			78				2,030			2,406
	Talbot FAL Facility	(169		)	32				(165		)	95
	Total finance expenses	$	15,354		$	15,317			$	47,380		$	47,252
	(a)	Includes finance expenses incurred by AlphaCat Managers, Ltd. in relation to fund raising for the AlphaCat ILS funds, AlphaCat 2014 and AlphaCat 2013.
Debt Information At Issuance [Member]	'
Debt Instruments [Line Items]	'
Schedule of long-term debt instruments [Table Text Block]	'
	The following table summarizes the key terms of the Company's senior notes and junior subordinated deferrable debentures as at the issuance date for each placement.
	Description	Issuance date	Commitment		Maturity date	Fixed/Spread			Interest payments due
	2006 Junior Subordinated Deferrable Debentures	June 15, 2006	$	150,000	June 15, 2036	9.069	%	(a)	Quarterly
	Flagstone 2006 Junior Subordinated Deferrable Debentures	August 23, 2006	$	136,403	September 15, 2036	3.54	%	(b)	Quarterly
	2007 Junior Subordinated Deferrable Debentures	June 21, 2007	$	200,000	June 15, 2037	8.48	%	(a)	Quarterly
	Flagstone 2007 Junior Subordinated Deferrable Debentures	June 8, 2007	$	88,750	July 30, 2037	3	%	(b)	Quarterly
	Flagstone 2007 Junior Subordinated Deferrable Debentures	September 20, 2007	$	25,000	September 15, 2037	3.1	%	(b)	Quarterly
	2010 Senior Notes due 2040	January 26, 2010	$	250,000	January 26, 2040	8.875	%	(a)	Semi-annually in arrears
	(a)	Fixed interest rate.
	(b)	Variable interest rate is the three-month LIBOR, reset quarterly, plus spread as noted in the table.
Debt Outstanding [Member]	'
Debt Instruments [Line Items]	'
Schedule of long-term debt instruments [Table Text Block]	'
	The following table summarizes the key terms of the Company's senior notes and junior subordinated deferrable debentures as at September 30, 2014:
	Description	Issuance date	Commitment		Maturity date	Fixed/Spread			Interest payments due
	2006 Junior Subordinated Deferrable Debentures	June 15, 2006	$	150,000	June 15, 2036	5.831	%	(b)	Quarterly
	Flagstone 2006 Junior Subordinated Deferrable Debentures	August 23, 2006	$	136,403	September 15, 2036	6.463	%	(b)	Quarterly
	2007 Junior Subordinated Deferrable Debentures	June 21, 2007	$	200,000	June 15, 2037	5.18	%	(b)	Quarterly
	Flagstone 2007 Junior Subordinated Deferrable Debentures	8-Jun-07	$	88,750	July 30, 2037	5.9	%	(b)	Quarterly
	Flagstone 2007 Junior Subordinated Deferrable Debentures	20-Sep-07	$	25,000	September 15, 2037	5.983	%	(b)	Quarterly
	2010 Senior Notes due 2040	26-Jan-10	$	250,000	January 26, 2040	8.875	%	(a)	Semi-annually in arrears
	(a)	Fixed interest rate.
	(b)	Interest rate has been fixed as a result of interest rate swap contracts entered into by the Company.

Accumulated_other_comprehensiv1

Accumulated other comprehensive (loss) income (Tables)	9 Months Ended
	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'
Schedule of changes in accumulated other comprehensive (loss) income	'
	The changes in accumulated other comprehensive (loss) income, by component for the three and nine months ended September 30, 2014 and 2013 is as follows:
		Three Months Ended						Nine Months Ended
		September 30,			September 30,			September 30,			September 30,
		2014			2013			2014			2013
	Balance - Beginning of period	$	2,460		$	(8,262	)	$	(617	)	$	(2,953	)
	Amounts reclassified to retained earnings	—			—			—			4,290
	Other comprehensive (loss) income	(5,198		)	4,390			(2,121		)	(5,209		)
	Balance - End of period	$	(2,738	)	$	(3,872	)	$	(2,738	)	$	(3,872	)

Commitments_and_contingencies_

Commitments and contingencies (Tables)	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Components of required capital	'
	The amounts of cash, investments and letters of credit provided for each year of account as follows:
		2014 Underwriting Year		2013 Underwriting Year
	Talbot FAL facility	$	25,000	$	25,000
	Group funds	450,000		403,700
	Total	$	475,000	$	428,700

Earnings_per_share_Tables

Earnings per share (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Computation of basic and earnings per diluted share	'
	The following table sets forth the computation of basic and earnings per diluted share for the three and nine months ended September 30, 2014 and 2013:
		Three Months Ended						Nine Months Ended
		September 30,			September 30,			September 30,			September 30,
		2014			2013			2014			2013
	Basic earnings per share
	Net (loss) income	$	(13,397	)	$	229,063		$	381,172		$	419,503
	Loss (income) attributable to noncontrolling interest	53,069			(45,694		)	(25,745		)	17,831
	Net income available to Validus	39,672			183,369			355,427			437,334
	Less: Dividends and distributions declared on outstanding warrants	(1,552		)	(1,552		)	(4,656		)	(17,662		)
	Income available to common shareholders	$	38,120		$	181,817		$	350,771		$	419,672
	Weighted average number of common shares outstanding	90,593,329			99,834,563			91,665,950			103,451,396
	Basic earnings per share available to common shareholders	$	0.42		$	1.82		$	3.83		$	4.06
	Earnings per diluted share
	Net (loss) income	$	(13,397	)	$	229,063		$	381,172		$	419,503
	Loss (income) attributable to noncontrolling interest	53,069			(45,694		)	(25,745		)	17,831
	Net income available to Validus	39,672			183,369			355,427			437,334
	Less: Dividends and distributions declared on outstanding warrants	(1,552		)	—			—			(17,662		)
	Income available to common shareholders	$	38,120		$	183,369		$	355,427		$	419,672
	Weighted average number of common shares outstanding	90,593,329			99,834,563			91,665,950			103,451,396
	Share equivalents:
	Warrants	—			2,606,669			2,747,399			—
	Stock options	760,267			782,158			752,145			1,090,298
	Unvested restricted shares	586,014			390,376			772,147			723,219
	Weighted average number of diluted common shares outstanding	91,939,610			103,613,766			95,937,641			105,264,913
	Earnings per diluted share available to common shareholders	$	0.41		$	1.77		$	3.7		$	3.99

Segment_information_Tables

Segment information (Tables)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Summary of results of operating segments and Corporate	'
	The following tables summarize the results of our operating segments and "Corporate":
	Three Months Ended September 30, 2014		Validus Re Segment				AlphaCat Segment				Talbot Segment				Corporate & Eliminations				Total
	Underwriting income
	Gross premiums written		$	114,897			$	6,936			$	245,685			$	(8,544	)		$	358,974
	Reinsurance premiums ceded		(10,899		)		(648		)		(27,134		)		8,544				(30,137		)
	Net premiums written		103,998				6,288				218,551				—				328,837
	Change in unearned premiums		122,712				28,850				14,297				—				165,859
	Net premiums earned		226,710				35,138				232,848				—				494,696
	Underwriting deductions
	Losses and loss expenses		102,005				3,738				118,382				—				224,125
	Policy acquisition costs		36,177				3,378				47,862				(1,013		)		86,404
	General and administrative expenses		18,522				7,719				37,709				19,369				83,319
	Share compensation expenses		2,582				179				2,990				3,013				8,764
	Total underwriting deductions		159,286				15,014				206,943				21,369				402,612
	Underwriting income (loss)		$	67,424			$	20,124			$	25,905			$	(21,369	)		$	92,084
	Net investment income		20,762				837				4,965				(1,303		)		25,261
	Other (loss) income		(6,827		)		5,980				109				(3,342		)		(4,080		)
	Finance expenses		(3,622		)		(385		)		162				(11,509		)		(15,354		)
	Operating income (loss) before taxes, income from operating affiliates and (income) attributable to operating affiliate investors		77,737				26,556				31,141				(37,523		)		97,911
	Tax benefit (expense)		1,058				—				332				(437		)		953
	Income from operating affiliates		—				3,761				—				—				3,761
	(Income) attributable to operating affiliate investors		—				(25,807		)		—				—				(25,807		)
	Net operating income (loss)		$	78,795			$	4,510			$	31,473			$	(37,960	)		$	76,818
	Net realized gains on investments		1,641				2,563				391				—				4,595
	Change in net unrealized (losses) on investments		(20,149		)		(60,253		)		(3,097		)		(1,475		)		(84,974		)
	Income from investment affiliate		1,754				—				—				—				1,754
	Foreign exchange (losses) gains		(6,056		)		(51		)		(7,114		)		1,780				(11,441		)
	Transaction expenses (b)		—				—				—				(149		)		(149		)
	Net income (loss)		$	55,985			$	(53,231	)		$	21,653			$	(37,804	)		$	(13,397	)
	Net loss attributable to noncontrolling interest		—				53,069				—				—				53,069
	Net income (loss) available (attributable) to Validus		$	55,985			$	(162	)		$	21,653			$	(37,804	)		$	39,672
	Selected ratios (a):
	Net premiums written / Gross premiums written		90.5		%		90.7		%		89		%						91.6		%
	Losses and loss expenses		45		%		10.6		%		50.8		%						45.3		%
	Policy acquisition costs		16		%		9.6		%		20.6		%						17.5		%
	General and administrative expenses (c)		9.3		%		22.5		%		17.5		%						18.6		%
	Expense ratio		25.3		%		32.1		%		38.1		%						36.1		%
	Combined ratio		70.3		%		42.7		%		88.9		%						81.4		%
	Total assets		$	4,716,426			$	1,688,191			$	2,898,755			$	749,678			$	10,053,050
	(a)	Ratios are based on net premiums earned.
	(b)	The transaction expenses relate to costs incurred in connection with the acquisition of Western World, which was completed on October 2, 2014. Western World results have not been included in the Company's consolidated results for the three months ended September 30, 2014. Transaction expenses are primarily comprised of legal, financial advisory and audit related services.
	(c)	The general and administrative expense ratio includes share compensation expenses.
	Three Months Ended September 30, 2013		Validus Re Segment				AlphaCat Segment				Talbot Segment				Corporate & Eliminations				Total
	Underwriting income
	Gross premiums written		$	130,925			$	3,481			$	246,468			$	(24,114	)		$	356,760
	Reinsurance premiums ceded		(13,006		)		(525		)		(49,998		)		24,114				(39,415		)
	Net premiums written		117,919				2,956				196,470				—				317,345
	Change in unearned premiums		157,873				34,210				21,860				—				213,943
	Net premiums earned		275,792				37,166				218,330				—				531,288
	Underwriting deductions
	Losses and loss expenses		62,250				15,615				100,100				—				177,965
	Policy acquisition costs		47,662				3,787				44,899				(1,448		)		94,900
	General and administrative expenses		19,785				5,728				37,402				18,174				81,089
	Share compensation expenses		2,479				152				2,992				4,904				10,527
	Total underwriting deductions		132,176				25,282				185,393				21,630				364,481
	Underwriting income (loss)		$	143,616			$	11,884			$	32,937			$	(21,630	)		$	166,807
	Net investment income		15,628				967				4,395				(981		)		20,009
	Other (loss) income		(1,892		)		3,791				73				(4,778		)		(2,806		)
	Finance expenses		(3,640		)		(80		)		(107		)		(11,490		)		(15,317		)
	Operating income (loss) before taxes, income from operating affiliates and (income) attributable to operating affiliate investors		153,712				16,562				37,298				(38,879		)		168,693
	Tax benefit (expense)		143				—				(513		)		365				(5		)
	Income from operating affiliates		—				1,463				—				—				1,463
	(Income) attributable to operating affiliate investors		—				(11,815		)		—				—				(11,815		)
Net operating income (loss)		$	153,855			$	6,210			$	36,785			$	(38,514	)		$	158,336
Net realized (losses) gains on investments		(10,137		)		4,084				(267		)		—				(6,320		)
Change in net unrealized gains on investments		23,144				44,145				2,678				—				69,967
Income from investment affiliate		1,044				—				—				—				1,044
Foreign exchange gains (losses)		2,168				388				4,238				(758		)		6,036
Net income (loss)		$	170,074			$	54,827			$	43,434			$	(39,272	)		$	229,063
Net income attributable to noncontrolling interest		—				(45,694		)		—				—				(45,694		)
Net income (loss) available (attributable) to Validus		$	170,074			$	9,133			$	43,434			$	(39,272	)		$	183,369
Selected ratios (a):
Net premiums written / Gross premiums written		90.1		%		84.9		%		79.7		%						89		%
Losses and loss expenses		22.6		%		42		%		45.8		%						33.5		%
Policy acquisition costs		17.3		%		10.2		%		20.6		%						17.9		%
General and administrative expenses (b)		8.1		%		15.8		%		18.5		%						17.2		%
Expense ratio		25.4		%		26		%		39.1		%						35.1		%
Combined ratio		48		%		68		%		84.9		%						68.6		%
Total assets		$	5,854,354			$	1,446,941			$	2,892,477			$	123,596			$	10,317,368
(a)	Ratios are based on net premiums earned.
(b)	The general and administrative expense ratio includes share compensation expenses.
Nine Months Ended September 30, 2014		Validus Re Segment				AlphaCat Segment				Talbot Segment				Corporate & Eliminations				Total
Underwriting income
Gross premiums written		$	1,104,169			$	135,073			$	854,324			$	(66,927	)		$	2,026,639
Reinsurance premiums ceded		(184,074		)		(4,348		)		(154,115		)		66,927				(275,610		)
Net premiums written		920,095				130,725				700,209				—				1,751,029
Change in unearned premiums		(233,271		)		(32,444		)		(41,658		)		—				(307,373		)
Net premiums earned		686,824				98,281				658,551				—				1,443,656
Underwriting deductions
Losses and loss expenses		247,848				(7,155		)		304,848				—				545,541
Policy acquisition costs		106,547				9,414				138,383				(3,338		)		251,006
General and administrative expenses		53,757				15,627				107,031				55,191				231,606
Share compensation expenses		7,126				330				8,434				8,362				24,252
Total underwriting deductions		415,278				18,216				558,696				60,215				1,052,405
Underwriting income (loss)		$	271,546			$	80,065			$	99,855			$	(60,215	)		$	391,251
Net investment income		56,285				2,546				14,322				(3,244		)		69,909
Other income (loss)		912				21,482				384				(7,793		)		14,985
Finance expenses		(11,131		)		(2,039		)		68				(34,278		)		(47,380		)
Operating income (loss) before taxes, income from operating affiliates and (income) attributable to operating affiliate investors		317,612				102,054				114,629				(105,530		)		428,765
Tax benefit (expense)		1,176				—				(902		)		(672		)		(398		)
Income from operating affiliates		—				13,580				—				—				13,580
(Income) attributable to operating affiliate investors		—				(82,833		)		—				—				(82,833		)
Net operating income (loss)		$	318,788			$	32,801			$	113,727			$	(106,202	)		$	359,114
Net realized gains on investments		5,411				10,230				552				—				16,193
Change in net unrealized gains (losses) on investments		5,279				15,706				2,159				(6,998		)		16,146
Income from investment affiliate		7,881				—				—				—				7,881
Foreign exchange (losses) gains		(9,384		)		(204		)		(5,897		)		724				(14,761		)
Transaction expenses (b)		—				—				—				(3,401		)		(3,401		)
Net income (loss)		$	327,975			$	58,533			$	110,541			$	(115,877	)		$	381,172
Net (income) attributable to noncontrolling interest		—				(25,745		)		—				—				(25,745		)
Net income (loss) available (attributable) to Validus		$	327,975			$	32,788			$	110,541			$	(115,877	)		$	355,427
Selected ratios (a):
Net premiums written / Gross premiums written		83.3		%		96.8		%		82		%						86.4		%
Losses and loss expenses		36.1		%		(7.3		)%		46.3		%						37.8		%
Policy acquisition costs		15.5		%		9.6		%		21		%						17.4		%
General and administrative expenses (c)		8.9		%		16.2		%		17.5		%						17.7		%
Expense ratio		24.4		%		25.8		%		38.5		%						35.1		%
Combined ratio		60.5		%		18.5		%		84.8		%						72.9		%
Total assets		$	4,716,426			$	1,688,191			$	2,898,755			$	749,678			$	10,053,050
(a)	Ratios are based on net premiums earned.
(b)	The transaction expenses relate to costs incurred in connection with the acquisition of Western World, which was completed on October 2, 2014. Western World results have not been included in the Company's consolidated results for the nine months ended September 30, 2014. Transaction expenses are primarily comprised of legal, financial advisory and audit related services.
(c)	The general and administrative expense ratio includes share compensation expenses.
Nine Months Ended September 30, 2013		Validus Re Segment				AlphaCat Segment				Talbot Segment				Corporate & Eliminations				Total
Underwriting income
Gross premiums written		$	1,232,272			$	146,757			$	855,516			$	(70,712	)		$	2,163,833
Reinsurance premiums ceded		(226,292		)		(525		)		(191,922		)		70,712				(348,027		)
Net premiums written		1,005,980				146,232				663,594				—				1,815,806
Change in unearned premiums		(122,303		)		(46,459		)		(37,237		)		—				(205,999		)
Net premiums earned		883,677				99,773				626,357				—				1,609,807
Underwriting deductions
Losses and loss expenses		319,298				16,928				251,554				—				587,780
Policy acquisition costs		142,195				10,011				127,092				(3,635		)		275,663
General and administrative expenses		69,649				13,757				100,506				48,423				232,335
Share compensation expenses		5,421				314				6,754				6,994				19,483
Total underwriting deductions		536,563				41,010				485,906				51,782				1,115,261
Underwriting income (loss)		$	347,114			$	58,763			$	140,451			$	(51,782	)		$	494,546
Net investment income		61,770				2,821				13,496				(6,219		)		71,868
Other income (loss)		11,237				17,439				564				(24,943		)		4,297
Finance expenses		(12,133		)		(4,273		)		(256		)		(30,590		)		(47,252		)
Operating income (loss) before taxes, income from operating affiliates and (income) attributable to operating affiliate investors		407,988				74,750				154,255				(113,534		)		523,459
Tax benefit (expense)		1,755				—				(1,184		)		(351		)		220
Income from operating affiliates		—				8,779				—				—				8,779
(Income) attributable to operating affiliate investors		—				(42,156		)		—				—				(42,156		)
Net operating income (loss)		$	409,743			$	41,373			$	153,071			$	(113,885	)		$	490,302
Net realized (losses) gains on investments		(5,790		)		4,084				516				—				(1,190		)
Change in net unrealized losses on investments		(36,883		)		(31,029		)		(10,706		)		—				(78,618		)
Income from investment affiliate		4,274				—				—				—				4,274
Foreign exchange gains (losses)		7,448				(663		)		(1,877		)		(173		)		4,735
Net income (loss)		$	378,792			$	13,765			$	141,004			$	(114,058	)		$	419,503
Net loss attributable to noncontrolling interest		—				17,831				—				—				17,831
Net income (loss) available (attributable) to Validus		$	378,792			$	31,596			$	141,004			$	(114,058	)		$	437,334
Selected ratios (a):
Net premiums written / Gross premiums written		81.6		%		99.6		%		77.6		%						83.9		%
Losses and loss expenses		36.1		%		17		%		40.2		%						36.5		%
Policy acquisition costs		16.1		%		10		%		20.3		%						17.2		%
General and administrative expenses (b)		8.5		%		14.1		%		17.1		%						15.6		%
Expense ratio		24.6		%		24.1		%		37.4		%						32.8		%
Combined ratio		60.7		%		41.1		%		77.6		%						69.3		%
Total assets		$	5,854,354			$	1,446,941			$	2,892,477			$	123,596			$	10,317,368
(a)	Ratios are based on net premiums earned.
(b)	The general and administrative expense ratio includes share compensation expenses.
Gross premiums written allocated to the territory of coverage exposure	'
	The following tables set forth the gross premiums written allocated to the territory of coverage exposure for the periods indicated:
		Three Months Ended September 30, 2014
		Gross Premiums Written
		Validus Re				AlphaCat				Talbot				Eliminations				Total				%
	United States	$	28,665			$	2,206			$	17,003			$	(874	)		$	47,000			13.1	%
	Worldwide excluding United States (a)	10,639				(81		)		29,781				(973		)		39,366				10.9	%
	Australia and New Zealand	610				—				3,312				(139		)		3,783				1.1	%
	Europe	8,560				312				9,821				(311		)		18,382				5.1	%
	Latin America and Caribbean	12,945				—				24,740				(819		)		36,866				10.3	%
	Japan	1,664				22				1,274				(73		)		2,887				0.8	%
	Canada	188				—				2,430				(80		)		2,538				0.7	%
	Rest of the world (b)	1,527				—				27,145				(1,073		)		27,599				7.7	%
	Sub-total, non United States	36,133				253				98,503				(3,468		)		131,421				36.6	%
	Worldwide including United States (a)	28,747				4,477				18,611				(560		)		51,275				14.3	%
	Other location non-specific (c)	21,352				—				111,568				(3,642		)		129,278				36	%
	Total	$	114,897			$	6,936			$	245,685			$	(8,544	)		$	358,974			100	%
		Three Months Ended September 30, 2013
		Gross Premiums Written
		Validus Re				AlphaCat				Talbot				Eliminations				Total				%
	United States	$	38,881			$	2,546			$	21,573			$	(2,105	)		$	60,895			17	%
	Worldwide excluding United States (a)	16,973				—				34,751				(4,138		)		47,586				13.3	%
	Australia and New Zealand	(9,482		)		33				2,905				(236		)		(6,780		)		(1.9	)%
	Europe	4,252				377				9,778				(986		)		13,421				3.8	%
	Latin America and Caribbean	5,902				—				38,084				(3,353		)		40,633				11.4	%
	Japan	(2,637		)		—				1,066				(117		)		(1,688		)		(0.5	)%
	Canada	1,469				500				2,749				(740		)		3,978				1.1	%
	Rest of the world (b)	5,641				—				22,167				(1,830		)		25,978				7.3	%
	Sub-total, non United States	22,118				910				111,500				(11,400		)		123,128				34.5	%
	Worldwide including United States (a)	29,611				25				18,246				(1,665		)		46,217				13	%
	Other location non-specific (c)	40,315				—				95,149				(8,944		)		126,520				35.5	%
	Total	$	130,925			$	3,481			$	246,468			$	(24,114	)		$	356,760			100	%
		Nine Months Ended September 30, 2014
		Gross Premiums Written
		Validus Re				AlphaCat				Talbot				Eliminations				Total				%
	United States	$	452,470			$	31,160			$	85,465			$	(10,662	)		$	558,433			27.5	%
	Worldwide excluding United States (a)	80,671				7,331				105,397				(6,741		)		186,658				9.2	%
	Australia and New Zealand	20,025				1,019				7,615				(391		)		28,268				1.4	%
	Europe	57,884				3,005				36,110				(4,157		)		92,842				4.6	%
	Latin America and Caribbean	22,167				—				86,111				(4,418		)		103,860				5.1	%
	Japan	41,137				608				3,404				(784		)		44,365				2.2	%
	Canada	3,508				215				8,325				(641		)		11,407				0.6	%
	Rest of the world (b)	23,870				—				70,702				(3,627		)		90,945				4.5	%
	Sub-total, non United States	249,262				12,178				317,664				(20,759		)		558,345				27.6	%
	Worldwide including United States (a)	168,337				91,735				71,147				(11,365		)		319,854				15.8	%
	Other location non-specific (c)	234,100				—				380,048				(24,141		)		590,007				29.1	%
	Total	$	1,104,169			$	135,073			$	854,324			$	(66,927	)		$	2,026,639			100	%
		Nine Months Ended September 30, 2013
		Gross Premiums Written
		Validus Re				AlphaCat				Talbot				Eliminations				Total				%
	United States	$	542,692			$	50,935			$	77,630			$	(10,599	)		$	660,658			30.6	%
	Worldwide excluding United States (a)	69,482				14,801				109,562				(9,065		)		184,780				8.4	%
	Australia and New Zealand	21,116				2,216				7,930				(467		)		30,795				1.4	%
	Europe	64,986				2,514				41,523				(3,892		)		105,131				4.9	%
	Latin America and Caribbean	5,885				—				124,120				(7,312		)		122,693				5.7	%
	Japan	41,939				653				5,258				(963		)		46,887				2.2	%
	Canada	4,503				818				8,790				(1,336		)		12,775				0.6	%
	Rest of the world (b)	29,211				—				62,803				(3,700		)		88,314				4.1	%
	Sub-total, non United States	237,122				21,002				359,986				(26,735		)		591,375				27.3	%
	Worldwide including United States (a)	180,621				74,820				63,998				(10,214		)		309,225				14.3	%
	Other location non-specific (c)	271,837				—				353,902				(23,164		)		602,575				27.8	%
	Total	$	1,232,272			$	146,757			$	855,516			$	(70,712	)		$	2,163,833			100	%
	(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, such as marine and aerospace risks, since these exposures can span multiple geographic areas and, in some instances, are not fixed locations.

Basis_of_preparation_and_conso1

Basis of preparation and consolidation (Details) (USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2013
Reclassification From Operating Cash To Financing Flows [Member]	'	'
Reclassification adjustment	'	$19,400
Reclassification Into Income Attributable To Operating Affiliate Investors From Finance Expenses [Member]	'	'
Reclassification adjustment	$11,815	$42,156

Investments_Gross_unrealized_g

Investments (Gross unrealized gains and losses on fixed maturities) (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Fixed maturities, at amortized cost or cost	$4,668,585		$5,522,853
Short-term investments, at amortized cost or cost	1,684,997	[1]	751,734	[2]
Other investments, at amortized cost or cost	714,508		637,728
Total investments including noncontrolling interests	7,068,090		6,912,315
Noncontrolling interest, amortized cost or cost	-502,830	[3]	-512,121	[3]
Redeemable noncontrolling interest, amortized cost or cost	-11,637	[1]	-18,365	[2]
Total investments excluding non-controlling interests, amortized cost or cost	6,553,623		6,381,829
Fixed maturities, gross unrealized gains	24,804		42,756
Short term investments, gross unrealized gains	4	[1]	45	[2]
Other investments, gross unrealized gains	109,296		76,843
Gross unrealized gains	134,104		119,644
Noncontrolling interest share of unrealized gains other investments	-86,263	[3]	-62,850	[3]
Total investments excluding non-controlling interest, unrealized gains	47,841		56,794
Fixed maturities, gross unrealized losses	-23,216		-23,351
Short term investments, gross unrealized losses	-19	[1]	-1	[2]
Other investments, gross unrealized losses	-105,171		-96,255
Gross unrealized losses	-128,406		-119,607
Noncontrolling interest share of unrealized losses	93,728	[3]	85,569	[3]
Total investments excluding non-controlling interest, unrealized losses	-34,678		-34,038
Total fixed maturities	4,670,173		5,542,258
Total short-term investments	1,684,982	[1]	751,778	[2]
Total other investments	718,633		618,316
Total	7,073,788		6,912,352
Noncontrolling interest	-495,365	[3]	-489,402	[3]
Redeemable noncontrolling interest	-11,637	[1]	-18,365	[2]
Total investments excluding noncontrolling interest	6,566,786		6,404,585
U.S. government and government agency	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Fixed maturities, at amortized cost or cost	786,318		1,368,826
Fixed maturities, gross unrealized gains	1,735		2,589
Fixed maturities, gross unrealized losses	-1,798		-6,736
Total fixed maturities	786,255		1,364,679
Non-U.S. government and government agency	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Fixed maturities, at amortized cost or cost	383,378		454,578
Fixed maturities, gross unrealized gains	1,775		6,511
Fixed maturities, gross unrealized losses	-3,956		-2,021
Total fixed maturities	381,197		459,068
U.S. states, municipalities and political subdivisions	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Fixed maturities, at amortized cost or cost	73,996		42,978
Fixed maturities, gross unrealized gains	557		459
Fixed maturities, gross unrealized losses	-188		-317
Total fixed maturities	74,365		43,120
Agency residential mortgage-backed securities	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Fixed maturities, at amortized cost or cost	368,646		305,450
Fixed maturities, gross unrealized gains	7,877		8,310
Fixed maturities, gross unrealized losses	-1,296		-2,261
Total fixed maturities	375,227		311,499
Non-agency residential mortgage-backed securities	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Fixed maturities, at amortized cost or cost	17,370		16,530
Fixed maturities, gross unrealized gains	238		143
Fixed maturities, gross unrealized losses	-409		-914
Total fixed maturities	17,199		15,759
U.S. corporate	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Fixed maturities, at amortized cost or cost	1,168,304		1,328,960
Fixed maturities, gross unrealized gains	5,601		9,208
Fixed maturities, gross unrealized losses	-4,987		-5,684
Total fixed maturities	1,168,918		1,332,484
Non-U.S. corporate	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Fixed maturities, at amortized cost or cost	593,619		711,581
Fixed maturities, gross unrealized gains	4,071		5,917
Fixed maturities, gross unrealized losses	-3,055		-3,173
Total fixed maturities	594,635		714,325
Bank loans	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Fixed maturities, at amortized cost or cost	488,904		712,859
Fixed maturities, gross unrealized gains	616		5,659
Fixed maturities, gross unrealized losses	-5,732		-1,402
Total fixed maturities	483,788		717,116
Catastrophe bonds	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Fixed maturities, at amortized cost or cost	47,574		72,000
Fixed maturities, gross unrealized gains	1,305		2,551
Fixed maturities, gross unrealized losses	-541		0
Total fixed maturities	48,338		74,551
Asset-backed securities	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Fixed maturities, at amortized cost or cost	566,135		509,091
Fixed maturities, gross unrealized gains	981		1,409
Fixed maturities, gross unrealized losses	-664		-843
Total fixed maturities	566,452		509,657
Commercial mortgage-backed securities	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Fixed maturities, at amortized cost or cost	174,341		'
Fixed maturities, gross unrealized gains	48		'
Fixed maturities, gross unrealized losses	-590		'
Total fixed maturities	173,799		'
Fund of hedge funds	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Other investments, at amortized cost or cost	2,802		3,141
Other investments, gross unrealized gains	162		83
Other investments, gross unrealized losses	-921		-921
Total other investments	2,043		2,303
Hedge funds	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Other investments, at amortized cost or cost	570,372	[3]	584,518	[3]
Other investments, gross unrealized gains	101,610	[3]	71,641	[3]
Other investments, gross unrealized losses	-104,142	[3]	-95,076	[3]
Total other investments	567,840	[3]	561,083	[3]
Private equity investments	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Other investments, at amortized cost or cost	11,295		12,333
Other investments, gross unrealized gains	3,832		1,410
Other investments, gross unrealized losses	-108		-258
Total other investments	15,019		13,485
Investment funds	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Other investments, at amortized cost or cost	123,840		31,537
Other investments, gross unrealized gains	350		92
Other investments, gross unrealized losses	0		0
Total other investments	124,190		31,629
Mutual funds	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Other investments, at amortized cost or cost	6,199		6,199
Other investments, gross unrealized gains	3,342		3,617
Other investments, gross unrealized losses	0		0
Total other investments	$9,541		$9,816
PaCRe funds	'		'
Amortized cost (or cost), gross unrealized gains and (losses) and estimated fair value of investments	'		'
Noncontrolling Interest, Ownership Percentage by Parent	10.00%		10.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	90.00%		90.00%
[1]	Included in the short-term investments balance are investments held by one AlphaCat ILS fund which is consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
[2]	Included in the short-term investments balance are investments held by two AlphaCat ILS funds which are consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
[3]	Included in the hedge funds balance are investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.

Investments_Fixed_maturities_b

Investments (Fixed maturities by investment rating) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fixed Maturities	'	'
Estimated fair value	$4,670,173	$5,542,258
Percentage of total	100.00%	100.00%
Investment Grade	'	'
Fixed Maturities	'	'
Estimated fair value	4,093,498	4,764,580
Percentage of total	87.70%	86.00%
AAA	'	'
Fixed Maturities	'	'
Estimated fair value	2,174,861	2,510,781
Percentage of total	46.60%	45.30%
AA	'	'
Fixed Maturities	'	'
Estimated fair value	594,858	696,998
Percentage of total	12.70%	12.60%
A	'	'
Fixed Maturities	'	'
Estimated fair value	960,153	1,233,716
Percentage of total	20.60%	22.30%
BBB	'	'
Fixed Maturities	'	'
Estimated fair value	363,626	323,085
Percentage of total	7.80%	5.80%
Non Investment Grade	'	'
Fixed Maturities	'	'
Estimated fair value	576,675	777,678
Percentage of total	12.30%	14.00%
BB	'	'
Fixed Maturities	'	'
Estimated fair value	283,954	354,992
Percentage of total	6.10%	6.40%
B	'	'
Fixed Maturities	'	'
Estimated fair value	269,380	383,639
Percentage of total	5.80%	6.90%
CCC	'	'
Fixed Maturities	'	'
Estimated fair value	1,341	2,453
Percentage of total	0.00%	0.00%
CC	'	'
Fixed Maturities	'	'
Estimated fair value	2,330	2,496
Percentage of total	0.00%	0.10%
C	'	'
Fixed Maturities	'	'
Estimated fair value	146	235
Percentage of total	0.00%	0.00%
D/NR	'	'
Fixed Maturities	'	'
Estimated fair value	$19,524	$33,863
Percentage of total	0.40%	0.60%

Investments_Maturity_profile_o

Investments (Maturity profile of fixed maturity investments) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Maturity profile	'	'
Amortized cost or cost	$4,668,585	$5,522,853
Estimated fair value	4,670,173	5,542,258
Fixed maturities trading securities allocated to contractual maturity	'	'
Maturity profile	'	'
Amortized cost or cost	3,542,093	4,691,782
Estimated fair value	3,537,496	4,705,343
Due in one year or less | Fixed maturities trading securities allocated to contractual maturity	'	'
Maturity profile	'	'
Amortized cost or cost	277,213	688,855
Estimated fair value	278,507	692,768
Due after one year through five years | Fixed maturities trading securities allocated to contractual maturity	'	'
Maturity profile	'	'
Amortized cost or cost	2,678,792	3,603,459
Estimated fair value	2,679,938	3,613,847
Due after five years through ten years | Fixed maturities trading securities allocated to contractual maturity	'	'
Maturity profile	'	'
Amortized cost or cost	496,922	396,389
Estimated fair value	491,364	395,633
Due after ten years | Fixed maturities trading securities allocated to contractual maturity	'	'
Maturity profile	'	'
Amortized cost or cost	89,166	3,079
Estimated fair value	87,687	3,095
Asset backed and mortgaged backed securities | No single maturity date	'	'
Maturity profile	'	'
Amortized cost or cost	1,126,492	831,071
Estimated fair value	$1,132,677	$836,915

Investments_Components_of_net_

Investments (Components of net investment income) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net investment income	'	'	'	'
Total gross investment income	$27,005	$22,018	$75,466	$77,862
Investment expenses	-1,744	-2,009	-5,557	-5,994
Net investment income	25,261	20,009	69,909	71,868
Fixed maturities and short term investments	'	'	'	'
Net investment income	'	'	'	'
Total gross investment income	22,544	20,936	68,048	74,618
Other investments [Member]	'	'	'	'
Net investment income	'	'	'	'
Total gross investment income	2,879	0	2,879	0
Cash and cash equivalents	'	'	'	'
Net investment income	'	'	'	'
Total gross investment income	1,581	1,079	4,534	3,241
Securities lending income	'	'	'	'
Net investment income	'	'	'	'
Total gross investment income	$1	$3	$5	$3

Investments_Realized_and_unrea

Investments (Realized and unrealized gains) (Details) (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014	Dec. 31, 2013
									PaCRe funds	PaCRe funds
Fixed maturities, short-term and other investments and cash equivalents	'		'		'		'		'	'
Gross realized gains	$8,075	[1]	$7,706	[1]	$23,184	[1]	$25,578	[1]	'	'
Gross realized (losses)	-3,480		-14,026		-6,991		-26,768		'	'
Net realized gains (losses) on investments	4,595		-6,320		16,193		-1,190		'	'
Change in net unrealized (losses) gains on investments	-84,974	[1]	69,967	[1]	16,146	[1]	-78,618	[1]	'	'
Total net realized gains (losses) and change in net unrealized (losses) gains on investments including noncontrolling interest	-80,379		63,647		32,339		-79,808		'	'
Noncontrolling interest	52,595	[1]	-42,579	[1]	-22,613	[1]	25,766	[1]	'	'
Total net realized gains (losses) and change in net unrealized (losses) gains on investments excluding noncontrolling interest	($27,784)		$21,068		$9,726		($54,042)		'	'
Noncontrolling Interest, Ownership Percentage by Parent	'		'		'		'		10.00%	10.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	'		'		'		'		90.00%	90.00%
[1]	Includes change in net unrealized gains (losses) and realized gains on investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and is included in the Consolidated Statements of Comprehensive Income as net loss (income) attributable to noncontrolling interest.

Investments_Investments_pledge

Investments (Investments pledged as collateral) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financial Instruments Owned and Pledged as Collateral [Line Items]	'	'
Credit facility, commitment	$1,605,000	$1,599,800
Letters of credit issued and outstanding	682,091	751,250
Investments pledged as collateral	1,043,338	1,246,406
$400,000 syndicated unsecured letter of credit facility	'	'
Financial Instruments Owned and Pledged as Collateral [Line Items]	'	'
Credit facility, commitment	400,000	400,000
Letters of credit issued and outstanding	0	0
Investments pledged as collateral	0	0
$525,000 syndicated secured letter of credit facility	'	'
Financial Instruments Owned and Pledged as Collateral [Line Items]	'	'
Credit facility, commitment	525,000	525,000
Letters of credit issued and outstanding	301,340	358,567
Investments pledged as collateral	393,720	507,620
$200,000 secured bi-lateral letter of credit facility	'	'
Financial Instruments Owned and Pledged as Collateral [Line Items]	'	'
Credit facility, commitment	200,000	200,000
Letters of credit issued and outstanding	19,743	16,726
Investments pledged as collateral	35,414	130,256
Talbot FAL Facility	'	'
Financial Instruments Owned and Pledged as Collateral [Line Items]	'	'
Credit facility, commitment	25,000	25,000
Letters of credit issued and outstanding	25,000	25,000
Investments pledged as collateral	31,054	30,801
PaCRe Senior secured letter of credit facility	'	'
Financial Instruments Owned and Pledged as Collateral [Line Items]	'	'
Credit facility, commitment	10,000	10,000
Letters of credit issued and outstanding	294	294
Investments pledged as collateral	0	0
AlphaCat Re secured letter of credit facility	'	'
Financial Instruments Owned and Pledged as Collateral [Line Items]	'	'
Credit facility, commitment	30,000	24,800
Letters of credit issued and outstanding	30,000	24,800
Investments pledged as collateral	30,059	24,806
IPC bi-lateral facility	'	'
Financial Instruments Owned and Pledged as Collateral [Line Items]	'	'
Credit facility, commitment	40,000	40,000
Letters of credit issued and outstanding	16,975	20,177
Investments pledged as collateral	96,633	98,465
$375,000 Flagstone bi-lateral facility	'	'
Financial Instruments Owned and Pledged as Collateral [Line Items]	'	'
Credit facility, commitment	375,000	375,000
Letters of credit issued and outstanding	288,739	305,686
Investments pledged as collateral	$456,458	$454,458

Investments_Narrative_Details

Investments (Narrative) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Trading Securities and Other Trading Assets [Line Items]	'	'
Cash, cash equivalents and investments pledged as collateral	$3,035,784	$2,947,475
Investments held in trust	$3,030,932	$2,942,508
AlphaCat ILS Funds	'	'
Schedule of Trading Securities and Other Trading Assets [Line Items]	'	'
Other Investments Number Of Funds	1	2

Fair_value_measurements_Fair_v

Fair value measurements (Fair value hierarchy) (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013		Sep. 30, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	$4,670,173		$5,542,258		'
Short-term investments, at fair value	1,684,982	[1]	751,778	[2]	'
Other investments, at fair value	718,633		618,316		'
Total	7,073,788		6,912,352		'
Noncontrolling interest	-495,365	[3]	-489,402	[3]	'
Redeemable noncontrolling interest share of VIE investments	-11,637	[1]	-18,365	[2]	'
Total investments excluding noncontrolling interest	6,566,786		6,404,585		'
U.S. government and government agency	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	786,255		1,364,679		'
Non-US government and government agency	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	381,197		459,068		'
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	74,365		43,120		'
Agency residential mortgage-backed securities	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	375,227		311,499		'
Non-Agency residential mortgage-backed securities	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	17,199		15,759		'
U.S. corporate	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	1,168,918		1,332,484		'
Non-U.S. corporate	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	594,635		714,325		'
Bank loans	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	483,788		717,116		'
Catastrophe bonds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	48,338		74,551		'
Asset-backed securities	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	566,452		509,657		'
Commercial mortgage-backed securities	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	173,799		'		'
Fund of hedge funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	2,043		2,303		'
Hedge funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	567,840	[3]	561,083	[3]	'
Private equity investments	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	15,019		13,485		'
Investment funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	124,190		31,629		'
Mutual funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	9,541		9,816		'
PaCRe funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Noncontrolling Interest, Ownership Percentage by Parent	10.00%		10.00%		'
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	90.00%		90.00%		'
Fair Value, Measurements, Recurring [Member]	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	4,670,173		5,542,258		'
Short-term investments, at fair value	1,684,982	[1],[3]	751,778	[2]	'
Other investments, at fair value	718,633		618,316		'
Total	7,073,788		6,912,352		'
Noncontrolling interest	-495,365	[3]	-489,402	[3]	'
Redeemable noncontrolling interest share of VIE investments	-11,637	[1]	-18,365	[2]	'
Total investments excluding noncontrolling interest	6,566,786		6,404,585		'
Fair Value, Measurements, Recurring [Member] | U.S. government and government agency	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	786,255		1,364,679		'
Fair Value, Measurements, Recurring [Member] | Non-US government and government agency	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	381,197		459,068		'
Fair Value, Measurements, Recurring [Member] | 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	74,365		43,120		'
Fair Value, Measurements, Recurring [Member] | Agency residential mortgage-backed securities	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	375,227		311,499		'
Fair Value, Measurements, Recurring [Member] | Non-Agency residential mortgage-backed securities	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	17,199		15,759		'
Fair Value, Measurements, Recurring [Member] | U.S. corporate	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	1,168,918		1,332,484		'
Fair Value, Measurements, Recurring [Member] | Non-U.S. corporate	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	594,635		714,325		'
Fair Value, Measurements, Recurring [Member] | Bank loans	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	483,788		717,116		'
Fair Value, Measurements, Recurring [Member] | Catastrophe bonds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	48,338		74,551		'
Fair Value, Measurements, Recurring [Member] | Asset-backed securities	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	566,452		509,657		'
Fair Value, Measurements, Recurring [Member] | Commercial mortgage-backed securities	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	173,799		'		'
Fair Value, Measurements, Recurring [Member] | Fund of hedge funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	2,043		2,303		'
Fair Value, Measurements, Recurring [Member] | Hedge funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	567,840	[3]	561,083	[3]	'
Fair Value, Measurements, Recurring [Member] | Private equity investments	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	15,019		13,485		'
Fair Value, Measurements, Recurring [Member] | Investment funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	124,190		31,629		'
Fair Value, Measurements, Recurring [Member] | Mutual funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	9,541		9,816		'
Fair Value, Measurements, Recurring [Member] | 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	1,671,911	[1],[3]	747,215	[2]	'
Other investments, at fair value	0		0		'
Total	1,671,911		747,215		'
Noncontrolling interest	0	[3]	0	[3]	'
Redeemable noncontrolling interest share of VIE investments	-11,637	[1]	-18,365	[2]	'
Total investments excluding noncontrolling interest	1,660,274		728,850		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | Level 1 | Bank loans	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	0		0		'
Fair Value, Measurements, Recurring [Member] | Level 1 | Catastrophe bonds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	0		0		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | 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		'		'
Fair Value, Measurements, Recurring [Member] | Level 1 | Fund of hedge funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	0		0		'
Fair Value, Measurements, Recurring [Member] | Level 1 | Hedge funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	0	[3]	0	[3]	'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | Level 1 | Investment funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	0		0		'
Fair Value, Measurements, Recurring [Member] | Level 1 | Mutual funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	0		0		'
Fair Value, Measurements, Recurring [Member] | Level 2	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	4,665,172		5,542,258		'
Short-term investments, at fair value	13,071	[1],[3]	4,563	[2]	'
Other investments, at fair value	30,851		41,445		'
Total	4,709,094		5,588,266		'
Noncontrolling interest	0	[3]	0	[3]	'
Redeemable noncontrolling interest share of VIE investments	0	[1]	0	[2]	'
Total investments excluding noncontrolling interest	4,709,094		5,588,266		'
Fair Value, Measurements, Recurring [Member] | 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	786,255		1,364,679		'
Fair Value, Measurements, Recurring [Member] | 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	381,197		459,068		'
Fair Value, Measurements, Recurring [Member] | 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	74,365		43,120		'
Fair Value, Measurements, Recurring [Member] | 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	375,227		311,499		'
Fair Value, Measurements, Recurring [Member] | 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	17,199		15,759		'
Fair Value, Measurements, Recurring [Member] | Level 2 | U.S. corporate	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	1,168,918		1,332,484		'
Fair Value, Measurements, Recurring [Member] | Level 2 | Non-U.S. corporate	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	594,635		714,325		'
Fair Value, Measurements, Recurring [Member] | Level 2 | Bank loans	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	483,788		717,116		'
Fair Value, Measurements, Recurring [Member] | Level 2 | Catastrophe bonds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	43,337		74,551		'
Fair Value, Measurements, Recurring [Member] | Level 2 | Asset-backed securities	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	566,452		509,657		'
Fair Value, Measurements, Recurring [Member] | Level 2 | Commercial mortgage-backed securities	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	173,799		'		'
Fair Value, Measurements, Recurring [Member] | Level 2 | Fund of hedge funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	0		0		'
Fair Value, Measurements, Recurring [Member] | Level 2 | Hedge funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	0	[3]	0	[3]	'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | Level 2 | Investment funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	21,310		31,629		'
Fair Value, Measurements, Recurring [Member] | Level 2 | Mutual funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	9,541		9,816		'
Fair Value, Measurements, Recurring [Member] | Level 3	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	5,001		0		'
Short-term investments, at fair value	0	[1],[3]	0	[2]	'
Other investments, at fair value	687,782		576,871		'
Total	692,783		576,871		'
Noncontrolling interest	-495,365	[3],[4]	-489,402	[3]	-465,472	[4]
Redeemable noncontrolling interest share of VIE investments	0	[1]	0	[2]	'
Total investments excluding noncontrolling interest	197,418		87,469		'
Percentage Of Fair Value Assets Measured On Recurring Basis	3.00%		1.40%		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | 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		'
Fair Value, Measurements, Recurring [Member] | Level 3 | Bank loans	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	0		0		'
Fair Value, Measurements, Recurring [Member] | Level 3 | Catastrophe bonds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	5,001		0		'
Fair Value, Measurements, Recurring [Member] | Level 3 | Asset-backed securities	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Fixed maturities, at fair value	0		0		'
Fair Value, Measurements, Recurring [Member] | 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		'		'
Fair Value, Measurements, Recurring [Member] | Level 3 | Fund of hedge funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	2,043		2,303		'
Fair Value, Measurements, Recurring [Member] | Level 3 | Hedge funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	567,840	[3]	561,083	[3]	'
Fair Value, Measurements, Recurring [Member] | Level 3 | Private equity investments	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	15,019		13,485		'
Fair Value, Measurements, Recurring [Member] | Level 3 | Investment funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	102,880		0		'
Fair Value, Measurements, Recurring [Member] | Level 3 | Mutual funds	'		'		'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'		'		'
Other investments, at fair value	$0		$0		'
[1]	Included in the short-term investments balance are investments held by one AlphaCat ILS fund which is consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
[2]	Included in the short-term investments balance are investments held by two AlphaCat ILS funds which are consolidated by the Company but in which the Company has an equity interest of less than 100%. The remaining interests are held by third party investors and included in the Consolidated Balance Sheets as redeemable noncontrolling interest.
[3]	Included in the hedge funds balance are investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.
[4]	Includes Level 3 investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.

Fair_value_measurements_Level_

Fair value measurements (Level 3 rollforward) (Details) (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Dec. 31, 2013
Reconciliation of beginning and ending balances for all investments measured at fair value on recurring basis	'		'		'		'		'
Noncontrolling interest	($495,365)	[1]	'		($495,365)	[1]	'		($489,402)	[1]
Fair Value, Measurements, Recurring [Member]	'		'		'		'		'
Reconciliation of beginning and ending balances for all investments measured at fair value on recurring basis	'		'		'		'		'
Noncontrolling interest	-495,365	[1]	'		-495,365	[1]	'		-489,402	[1]
Level 3 | Fair Value, Measurements, Recurring [Member]	'		'		'		'		'
Reconciliation of beginning and ending balances for all investments measured at fair value on recurring basis	'		'		'		'		'
Level 3 investments - beginning of period	746,396		505,158		576,871		556,234		'
Purchases	25,784		33,154		125,784		98,669		'
Sales	-24,175		-35,264		-49,508		-80,095		'
Settlements	0		0		-1,500		0		'
Realized gains	2,554		4,503		8,198		4,843		'
Unrealized losses	-57,776		42,917		26,235		-29,183		'
Transfers	0		0		6,703		0		'
Level 3 investments - end of period	692,783		550,468		692,783		550,468		'
Noncontrolling interest	-495,365	[1],[2]	-465,472	[2]	-495,365	[1],[2]	-465,472	[2]	-489,402	[1]
Investments excluding noncontrolling interest level three rollforward	$197,418		$84,996		$197,418		$84,996		'
PaCRe funds	'		'		'		'		'
Reconciliation of beginning and ending balances for all investments measured at fair value on recurring basis	'		'		'		'		'
Noncontrolling Interest, Ownership Percentage by Parent	10.00%		'		10.00%		'		10.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	90.00%		'		90.00%		'		90.00%
[1]	Included in the hedge funds balance are investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.
[2]	Includes Level 3 investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.

Fair_value_measurements_Narrat

Fair value measurements (Narrative) (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	$718,633		$618,316
Mutual funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	9,541		9,816
Other Investments Number Of Funds	2		'
Hedge funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	567,840	[1]	561,083	[1]
Fund of hedge funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	2,043		2,303
Investment Time Lag Reporting	'1 month		'
Investments assumed in Flagstone acquisition	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Investment Time Lag Reporting	'3 months		'
Other Investments Number Of Funds	1		'
PaCRe funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Noncontrolling Interest, Ownership Percentage by Parent	10.00%		10.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	90.00%		90.00%
Investment Time Lag Reporting	'1 month		'
Other Investments Number Of Funds	5		'
Investment funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	124,190		31,629
Private equity investments	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	15,019		13,485
Fair Value, Measurements, Recurring [Member]	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	718,633		618,316
Fair Value, Measurements, Recurring [Member] | Mutual funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	9,541		9,816
Fair Value, Measurements, Recurring [Member] | Hedge funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	567,840	[1]	561,083	[1]
Fair Value, Measurements, Recurring [Member] | Fund of hedge funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	2,043		2,303
Fair Value, Measurements, Recurring [Member] | Investment funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	124,190		31,629
Fair Value, Measurements, Recurring [Member] | Private equity investments	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	15,019		13,485
Minimum [Member] | Private equity investments	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Investment Time Lag Reporting	'3 months		'
Maximum | Private equity investments	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Investment Time Lag Reporting	'6 months		'
Fair Value, Inputs, Level 2 [Member] | Investment funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other Investments Number Of Funds	1		'
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	30,851		41,445
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	9,541		9,816
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Hedge funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	0	[1]	0	[1]
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Fund of hedge funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	0		0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Investment funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	21,310		31,629
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Private equity investments	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	0		0
Fair Value, Inputs, Level 3 [Member] | Investment funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Investment Time Lag Reporting	'1 month		'
Other Investments Number Of Funds	1		'
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	687,782		576,871
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Hedge funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	567,840	[1]	561,083	[1]
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Fund of hedge funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	2,043		2,303
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Investment funds	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	102,880		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Private equity investments	'		'
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]	'		'
Other investments, at fair value	$15,019		$13,485
[1]	Included in the hedge funds balance are investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and included in the Consolidated Balance Sheets as noncontrolling interest.

Investments_in_affiliates_Summ

Investments in affiliates (Summary of investments in affiliates) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Equity Method Investments [Line Items]	'	'
Investments in affiliates	$217,612	$141,243
Investment affiliate	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Investments in affiliates	42,381	34,500
Operating affiliates	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Investments in affiliates	$175,231	$106,743

Investments_in_affiliates_Inve

Investments in affiliates (Investment affiliate rollforward) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Schedule of Equity Method Investments [Line Items]	'	'	'	'
Income from investment affiliate	$1,754	$1,044	$7,881	$4,274
Investment affiliate | Aquiline Financial Services Fund II LP	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'
Balance, beginning of period	40,627	25,352	34,500	15,218
Capital contributions	0	6,185	0	13,089
Income from investment affiliate	1,754	1,044	7,881	4,274
Balance, end of period	$42,381	$32,581	$42,381	$32,581

Investments_in_affiliates_Inve1

Investments in affiliates (Investment affiliate details) (Details) (Investment affiliate, Aquiline Financial Services Fund II LP, USD $)	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Investment affiliate | Aquiline Financial Services Fund II LP	'	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'	'
Investment at cost	$32,110	'	$32,110	'	'	'
Voting ownership %	0.00%	'	0.00%	'	'	'
Equity ownership %	6.70%	'	6.70%	'	'	'
Carrying value	$42,381	$40,627	$34,500	$32,581	$25,352	$15,218

Investments_in_affiliates_Oper

Investments in affiliates (Operating affiliates rollforward) (Details) (USD $)	3 Months Ended			9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013
Activity in non-consolidated affiliate balances for the period:	'		'	'		'
Income from operating affiliates	$3,761		$1,463	$13,580		$8,779
Operating affiliates	'		'	'		'
Activity in non-consolidated affiliate balances for the period:	'		'	'		'
Balance, beginning of period	172,992		85,120	106,743		157,111
Return of investment	-1,522		-7,350	-58,547		-86,657
Fair value of retained interest on deconsolidation of AlphaCat ILS fund	'		'	113,455		'
Income from operating affiliates	3,761		1,463	13,580		8,779
Balance, end of period	175,231		79,233	175,231		79,233
Operating affiliates | AlphaCat Re 2011	'		'	'		'
Activity in non-consolidated affiliate balances for the period:	'		'	'		'
Balance, beginning of period	4,172		11,054	9,809		62,792
Return of investment	0		-2,800	-5,825		-54,914
Income from operating affiliates	-5		-270	183		106
Balance, end of period	4,167		7,984	4,167		7,984
Operating affiliates | AlphaCat Re 2012	'		'	'		'
Activity in non-consolidated affiliate balances for the period:	'		'	'		'
Balance, beginning of period	2,204		5,204	1,313		29,319
Return of investment	-1,516		-4,550	-1,516		-31,743
Income from operating affiliates	-9		-7	882		3,071
Balance, end of period	679		647	679		647
Operating affiliates | AlphaCat 2013	'		'	'		'
Activity in non-consolidated affiliate balances for the period:	'		'	'		'
Balance, beginning of period	2,580		48,536	51,744		45,000
Return of investment	-6		0	-51,206		0
Income from operating affiliates	7		585	2,043		4,121
Balance, end of period	2,581		49,121	2,581		49,121
Operating affiliates | AlphaCat 2014	'		'	'		'
Activity in non-consolidated affiliate balances for the period:	'		'	'		'
Balance, beginning of period	25,014		'	21,982		'
Return of investment	0		'	0		'
Income from operating affiliates	1,367		'	4,399		'
Balance, end of period	26,381		'	26,381		'
Operating affiliates | AlphaCat ILS Funds	'		'	'		'
Activity in non-consolidated affiliate balances for the period:	'		'	'		'
Balance, beginning of period	139,022		20,326	21,895		20,000
Return of investment	0		0	0		0
Fair value of retained interest on deconsolidation of AlphaCat ILS fund	'		'	113,455		'
Income from operating affiliates	2,401		1,155	6,073		1,481
Balance, end of period	$141,423	[1]	$21,481	$141,423	[1]	$21,481
[1]	Equity ownership in the two funds were 7.9% and 49.0% respectively as at September 30, 2014.

Investments_in_affiliates_Oper1

Investments in affiliates (Operating affiliates details) (Details) (Operating affiliates, USD $)	Sep. 30, 2014		Jun. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Investment:	'		'	'	'	'	'
Investment at cost	$162,882		'	$97,536	'	'	'
Carrying value	175,231		172,992	106,743	79,233	85,120	157,111
AlphaCat Re 2011	'		'	'	'	'	'
Investment:	'		'	'	'	'	'
Investment at cost	4,167		'	9,882	'	'	'
Voting ownership %	43.70%		'	43.70%	'	'	'
Equity ownership %	22.30%		'	22.30%	'	'	'
Carrying value	4,167		4,172	9,809	7,984	11,054	62,792
AlphaCat Re 2012	'		'	'	'	'	'
Investment:	'		'	'	'	'	'
Investment at cost	679		'	654	'	'	'
Voting ownership %	49.00%		'	49.00%	'	'	'
Equity ownership %	37.90%		'	37.90%	'	'	'
Carrying value	679		2,204	1,313	647	5,204	29,319
AlphaCat 2013	'		'	'	'	'	'
Investment:	'		'	'	'	'	'
Investment at cost	2,581		'	45,000	'	'	'
Voting ownership %	40.90%		'	40.90%	'	'	'
Equity ownership %	19.70%		'	19.70%	'	'	'
Carrying value	2,581		2,580	51,744	49,121	48,536	45,000
AlphaCat 2014	'		'	'	'	'	'
Investment:	'		'	'	'	'	'
Investment at cost	22,000		'	22,000	'	'	'
Voting ownership %	42.30%		'	42.30%	'	'	'
Equity ownership %	19.60%		'	19.60%	'	'	'
Carrying value	26,381		25,014	21,982	'	'	'
AlphaCat ILS Funds	'		'	'	'	'	'
Investment:	'		'	'	'	'	'
Investment at cost	133,455	[1]	'	20,000	'	'	'
Equity ownership %	'		'	9.10%	'	'	'
Carrying value	$141,423	[1]	$139,022	$21,895	$21,481	$20,326	$20,000
[1]	Equity ownership in the two funds were 7.9% and 49.0% respectively as at September 30, 2014.

Investments_in_affiliates_Note

Investments in affiliates (Notes payable and (income) attributable to operating affiliates) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Schedule of Equity Method Investments [Line Items]	'	'	'	'
Variable Funding Notes, Typical Minimum Duration	'	'	'12 months	'
Notes payable to operating affiliates, beginning of period	'	'	$439,272	'
Redemption of notes payable to operating affiliates	'	-3,553	'	-3,553
Notes payable to operating affiliates, end of period	655,976	'	655,976	'
Variable interest entity, not primary beneficiary	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'
Notes payable to operating affiliates, beginning of period	622,950	431,093	439,272	0
Notes payable to operating affiliates recognized on deconsolidation of AlphaCat ILS fund	'	'	178,837	'
Issuance of notes payable to operating affiliates	53,498	6,733	645,243	441,126
Redemption of notes payable to operating affiliates	-13,990	'	-602,068	'
Foreign exchange gain (loss)	-6,482	3,697	-5,308	397
Notes payable to operating affiliates, end of period	655,976	437,970	655,976	437,970
Variable interest entity, not primary beneficiary | AlphaCat 2013	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'
Notes payable to operating affiliates, beginning of period	0	222,135	223,809	0
Notes payable to operating affiliates recognized on deconsolidation of AlphaCat ILS fund	'	'	0	'
Issuance of notes payable to operating affiliates	0	0	0	223,082
Redemption of notes payable to operating affiliates	0	0	-223,512	0
Foreign exchange gain (loss)	0	1,196	-297	249
Notes payable to operating affiliates, end of period	0	223,331	0	223,331
Variable interest entity, not primary beneficiary | AlphaCat 2014	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'
Notes payable to operating affiliates, beginning of period	157,992	'	0	'
Notes payable to operating affiliates recognized on deconsolidation of AlphaCat ILS fund	'	'	0	'
Issuance of notes payable to operating affiliates	0	'	157,914	'
Redemption of notes payable to operating affiliates	0	'	0	'
Foreign exchange gain (loss)	-410	'	-332	'
Notes payable to operating affiliates, end of period	157,582	'	157,582	'
Variable interest entity, not primary beneficiary | AlphaCat ILS Funds	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'
Notes payable to operating affiliates, beginning of period	464,958	208,958	215,463	0
Notes payable to operating affiliates recognized on deconsolidation of AlphaCat ILS fund	'	'	178,837	'
Issuance of notes payable to operating affiliates	53,498	6,733	487,329	218,044
Redemption of notes payable to operating affiliates	-13,990	-3,553	-378,556	-3,553
Foreign exchange gain (loss)	-6,072	2,501	-4,679	148
Notes payable to operating affiliates, end of period	$498,394	$214,639	$498,394	$214,639

Investments_in_affiliates_Inco

Investments in affiliates (Income attributable to operating affiliates) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Schedule of Equity Method Investments [Line Items]	'	'	'	'
(Income) attributable to operating affiliate investors	($25,807)	($11,815)	($82,833)	($42,156)
Variable interest entity, not primary beneficiary | AlphaCat 2013	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'
(Income) attributable to operating affiliate investors	-98	-4,074	-14,218	-29,357
Variable interest entity, not primary beneficiary | AlphaCat 2014	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'
(Income) attributable to operating affiliate investors	-11,309	0	-32,990	0
Variable interest entity, not primary beneficiary | AlphaCat ILS Funds	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'
(Income) attributable to operating affiliate investors	($14,400)	($7,741)	($35,625)	($12,799)

Investments_in_affiliates_Narr

Investments in affiliates (Narrative) (Details) (USD $)

3 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

In Thousands, unless otherwise specified

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Jan. 31, 2014

Dec. 20, 2011

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

AlphaCat ILS Funds

AlphaCat ILS Funds

Aquiline Financial Services Fund II LP

Aquiline Financial Services Fund II LP

Operating affiliates

Operating affiliates

Operating affiliates

Operating affiliates

Operating affiliates

Operating affiliates

Operating affiliates

As investor in third party economic interests

As investor in third party economic interests

As investor in third party economic interests

As investor in third party economic interests

As investor in third party economic interests

Equity Method Investments [Member]

Equity Method Investments [Member]

Equity Method Investments [Member]

Variable Interest Entity, Primary Beneficiary [Member]

Variable Interest Entity, Primary Beneficiary [Member]

funds

AlphaCat ILS Funds

AlphaCat ILS Funds

AlphaCat ILS Funds

AlphaCat ILS Funds

Operating affiliates

AlphaCat ILS Funds

Operating affiliates

funds

funds

AlphaCat ILS Funds

funds

AlphaCat ILS Funds

Schedule of Equity Method Investments [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of Assignor's interest assumed

'

'

'

'

'

100.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total capital commitment

'

'

'

'

'

$50,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Investment Time Lag Reporting

'

'

'

'

'

'

'3 months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other Investments Number Of Funds

'

'

'

3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2

1

'

1

'

Third party subscriptions

'

'

'

'

35,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Threshold Minimum Consolidation Requirement Percentage

'

'

'

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fair value of retained interest on deconsolidation of AlphaCat ILS fund

'

'

'

'

'

'

'

'

'

113,455

'

'

113,455

'

'

'

'

'

'

'

'

'

'

'

Deconsolidation, Gain (Loss), Amount

'

1,372

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Equity ownership %

'

'

'

'

'

'

'

'

'

'

'

'

'

9.10%

'

'

'

'

'

'

'

7.90%

'

49.00%

Variable Interest Entity Redemption Of Notes Payable To Operating Affiliates

3,553

'

3,553

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Variable Funding Notes, Typical Minimum Duration

'

'12 months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Notes Payable Of Operating Affiliates Portion Due to Company

'

'

'

'

'

'

'

164,169

'

164,169

'

63,654

'

'

491,807

'

491,807

'

375,618

'

'

'

'

'

Income Attributable To Operating Affiliates Portion Due to Company

'

'

'

'

'

'

'

$4,993

$1,505

$16,552

$7,114

'

'

'

$20,814

$10,310

$66,281

$35,042

'

'

'

'

'

'

Noncontrolling_interest_Detail

Noncontrolling interest (Details) (USD $)

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

In Thousands, unless otherwise specified

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

PaCRe funds

PaCRe funds

AlphaCat ILS Funds

AlphaCat ILS Funds

Redeemable noncontrolling interest

Redeemable noncontrolling interest

Redeemable noncontrolling interest

Redeemable noncontrolling interest

Noncontrolling interest

Noncontrolling interest

Noncontrolling interest

Noncontrolling interest

funds

funds

funds

Noncontrolling Interest [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other Investments Number Of Funds

'

'

'

'

5

'

1

2

'

'

'

'

'

'

'

'

Noncontrolling Interest, Ownership Percentage by Parent

'

'

'

'

10.00%

10.00%

'

'

'

'

'

'

'

'

'

'

Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners

'

'

'

'

90.00%

90.00%

'

'

'

'

'

'

'

'

'

'

Redeemable noncontrolling interest and noncontrolling interest, rollforward:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Redeemable noncontrolling interest and noncontrolling interest, beginning of period

$641,629

$498,445

$584,169

$434,280

'

'

'

'

$66,282

$70,690

$86,512

$0

$575,347

$427,755

$497,657

$434,280

Issuance of shares

4,200

13,000

61,200

140,690

'

'

'

'

4,200

13,000

61,200

82,190

0

0

0

58,500

Income (loss) attributable to noncontrolling interest

-53,069

45,694

25,745

-17,831

'

'

'

'

-9

1,516

1,115

3,016

-53,060

44,178

24,630

-20,847

Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests

'

10,207

'

10,207

'

'

'

'

'

10,207

'

10,207

'

0

'

0

Noncontrolling Interest, Decrease from Deconsolidation

'

'

78,354

'

'

'

'

'

'

'

78,354

'

'

'

0

'

Redeemable noncontrolling interest and noncontrolling interest, end of period

$592,760

$546,932

$592,760

$546,932

'

'

'

'

$70,473

$74,999

$70,473

$74,999

$522,287

$471,933

$522,287

$471,933

Derivative_instruments_Amount_

Derivative instruments (Amount and balance sheet location) (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Designated as hedging instruments | Foreign exchange contracts	'		'
Summary of amount of derivatives designated as hedging instruments	'		'
Net Notional Exposure	$246,638		$163,576
Designated as hedging instruments | Foreign exchange contracts | Other assets	'		'
Summary of amount of derivatives designated as hedging instruments	'		'
Asset Derivative at Fair Value	592	[1]	1,167	[1]
Designated as hedging instruments | Foreign exchange contracts | Accounts payable and accrued expenses	'		'
Summary of amount of derivatives designated as hedging instruments	'		'
Liability Derivative at Fair Value	16,672	[1]	2,313	[1]
Designated as hedging instruments | Interest rate swap contracts	'		'
Summary of amount of derivatives designated as hedging instruments	'		'
Net Notional Exposure	552,263		552,263
Designated as hedging instruments | Interest rate swap contracts | Other assets	'		'
Summary of amount of derivatives designated as hedging instruments	'		'
Asset Derivative at Fair Value	25	[1]	28	[1]
Designated as hedging instruments | Interest rate swap contracts | Accounts payable and accrued expenses	'		'
Summary of amount of derivatives designated as hedging instruments	'		'
Liability Derivative at Fair Value	$912	[1]	$911	[1]
Junior Subordinated Deferrable Debentures | Interest rate swap contracts	'		'
Derivatives, Fair Value [Line Items]	'		'
Derivative, Number of Instruments Held	2		'
Flagstone Junior Subordinated Deferrable Debentures | Interest rate swap contracts	'		'
Derivatives, Fair Value [Line Items]	'		'
Derivative, Number of Instruments Held	3		'
Flagstone Junior Subordinated Deferrable Debentures | Cross-currency interest rate swap	'		'
Derivatives, Fair Value [Line Items]	'		'
Derivative, Number of Instruments Held	1		'
[1]	Asset and liability derivatives are classified within other assets and accounts payable and accrued expenses respectively on the Consolidated Balance Sheets.

Derivative_instruments_Amount_1

Derivative instruments (Amount included in statement of operations) (Details) (Designated as hedging instruments, USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair value hedge | Foreign exchange contracts | Foreign exchange gains (losses)	'	'	'	'
Derivatives designated as fair value hedges and related hedged item	'	'	'	'
Amount of gain (loss) recognized in income on derivative	($14,817)	$3,116	($9,979)	$2,670
Amount of (loss) gain on hedged item recognized in income attributable to risk being hedged	14,817	-3,116	9,979	-2,670
Amount of gain (loss) recognized in income on derivative (ineffective portion)	0	0	0	0
Cash flow hedge | Interest rate swap contracts	'	'	'	'
Derivative instruments designated as a cash flow hedge	'	'	'	'
Amount of ineffective portion excluded from effectiveness testing	0	0	0	0
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	3,302	3,268	9,762	7,838
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	($3,302)	($3,268)	($9,762)	($7,838)

Reserve_for_losses_and_loss_ex2

Reserve for losses and loss expenses (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reserve for paid losses and unpaid loss expenses	'	'	'	'
Reserve for losses and loss expenses, beginning of period	$2,867,307	$3,283,450	$3,030,399	$3,517,573
Losses and loss expenses recoverable, beginning of period	-338,734	-418,693	-370,154	-439,967
Net reserves for losses and loss expenses, beginning of period	2,528,573	2,864,757	2,660,245	3,077,606
Net reserves disposed	0	0	0	-18,591
Increase (decrease) in net losses and loss expenses incurred in respect of losses occurring in:	'	'	'	'
Current year	279,690	243,015	713,177	759,617
Prior years	-55,565	-65,050	-167,636	-171,837
Total incurred losses and loss expenses	224,125	177,965	545,541	587,780
Less net losses and loss expenses paid in respect of losses occurring in:	'	'	'	'
Current year	-74,618	-59,701	-99,326	-95,535
Prior years	-183,697	-215,167	-633,048	-732,118
Total net paid losses	-258,315	-274,868	-732,374	-827,653
Foreign exchange	-40,717	34,363	-19,746	-16,925
Net reserve for losses and loss expenses, end of period	2,453,666	2,802,217	2,453,666	2,802,217
Losses and loss expenses recoverable, end of period	298,502	421,518	298,502	421,518
Reserve for losses and loss expenses, end of period	2,752,168	3,223,735	2,752,168	3,223,735
Components of incurred losses and loss expenses	'	'	'	'
Gross losses and loss expenses	222,356	226,130	587,111	684,080
Reinsurance recoverable	1,769	-48,165	-41,570	-96,300
Net incurred losses and loss expenses	$224,125	$177,965	$545,541	$587,780

Reinsurance_Details

Reinsurance (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	$361,493	$450,234
Percentage of reinsurance recoverables	100.00%	100.00%
Reinsurance (Textuals) [Abstract]	'	'
Incurred but not reported recoverable	144,414	196,840
Provision for uncollectible reinsurance relating to losses recoverable	5,380	5,794
A- or better	'	'
Ceded Credit Risk [Line Items]	'	'
Percentage of reinsurance recoverables	97.30%	96.70%
Top 10 reinsurers	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	264,131	340,253
Percentage of reinsurance recoverables	73.10%	75.60%
Top 10 reinsurers | Lloyd's Syndicates | A plus	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	60,218	73,398
Percentage of reinsurance recoverables	16.70%	16.30%
Top 10 reinsurers | National Indemnity | AA plus	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	'	51,037
Percentage of reinsurance recoverables	'	11.30%
Top 10 reinsurers | Everest Re | A plus	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	46,765	48,055
Percentage of reinsurance recoverables	12.90%	10.70%
Top 10 reinsurers | Third Point Re | A-	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	34,180	30,428
Percentage of reinsurance recoverables	9.50%	6.80%
Top 10 reinsurers | Fully Collateralized | NR	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	33,770	36,683
Percentage of reinsurance recoverables	9.30%	8.10%
Top 10 reinsurers | Hannover Re | AA-	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	33,124	41,483
Percentage of reinsurance recoverables	9.20%	9.20%
Top 10 reinsurers | Swiss Re | AA-	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	13,849	20,022
Percentage of reinsurance recoverables	3.80%	4.50%
Top 10 reinsurers | Transatlantic Re | A plus	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	11,649	14,114
Percentage of reinsurance recoverables	3.20%	3.10%
Top 10 reinsurers | XL Re | A plus	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	10,334	12,673
Percentage of reinsurance recoverables	2.90%	2.80%
Top 10 reinsurers | Munich Re | AA-	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	10,232	12,360
Percentage of reinsurance recoverables	2.80%	2.80%
Top 10 reinsurers | Aioi Nissay Dowa Insurance | A plus	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	10,010	'
Percentage of reinsurance recoverables	2.80%	'
Other reinsurers' balances greater than $1 million	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	89,584	100,784
Percentage of reinsurance recoverables	24.80%	22.40%
Other reinsurers' balances less than $1 million	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverable	$7,778	$9,197
Percentage of reinsurance recoverables	2.10%	2.00%

Share_capital_Details

Share capital (Details) (USD $)

0 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

In Thousands, except Share data, unless otherwise specified

Feb. 05, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Mar. 31, 2013

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Mar. 31, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Common shares

Common shares

Common shares

Common shares

Common shares

Common shares

Common shares

Common share equivalents

Common share equivalents

Common share equivalents

Common share equivalents

Performance shares

Performance shares

Warrants

Warrants

Deferred share units

Restricted share awards

Restricted share awards

Restricted share units

Restricted share units

Employee director

Special dividend declared

Special dividend declared

Deferred share units

Share Capital (Narrative)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common shares, shares authorized

'

571,428,571

'

571,428,571

'

571,428,571

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common shares, par value

'

$0.18

'

$0.18

'

$0.18

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock voting rights

'

'

'

'one vote per share

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restriction on percentage of voting power

'

'

'

9.09%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share repurchases

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Repurchase Program, Authorized Amount

$500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share repurchase program, cumulative shares repurchased

'

'

'

64,502,410

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares repurchased, cumulative

1,774,436

'

'

2,006,875

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Remaining share repurchase authorization amount

'

'

'

$267,561

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of warrants exercised during period

'

'

'

'

1,114,416

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

Class of Warrant or Right, Outstanding

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,174,114

5,296,056

'

'

'

'

'

'

Deferred share units, adjustment factor

'

'

'

100.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total outstanding deferred share units

'

0

'

0

'

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Vested (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

32,746

39,094

'

'

'

769,971

930,296

18,325

21,814

5,039

Cash dividends declared per share

'

$0.30

$0.30

$0.90

$2.90

'

$0.30

$0.30

$0.30

$0.30

$0.30

$0.30

$2

$0.30

$0.30

$0.30

$2

'

'

'

'

'

'

'

'

'

'

Summary of common shares issued and outstanding

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common shares issued, beginning balance

'

'

'

154,488,497

152,698,191

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Vested, net of shares withheld

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

25,767

31,897

'

'

'

594,582

768,889

10,265

14,381

'

Options exercised (in shares)

'

'

'

133,385

277,615

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Warrants exercised

'

'

'

'

591,480

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Direct issuance of common stock

'

'

'

1,060

928

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Deferred share units vested, net of shares withheld

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,935

'

'

'

'

2,935

Common shares issued, ending balance

'

155,253,556

154,386,316

155,253,556

154,386,316

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares repurchased, ending balance

'

-66,141,285

-54,488,320

-66,141,285

-54,488,320

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common shares outstanding, ending balance

'

89,112,271

99,897,996

89,112,271

99,897,996

96,044,312

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock_plans_Options_activity_D

Stock plans (Options activity) (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Options activities:	'	'
Options outstanding, beginning balance (in shares)	1,572,713	1,823,947
Options regranted (modified) (in shares)	'	1,833,414
Options exercised (in shares)	-133,385	-277,615
Options cancelled (modified) (in shares)	'	-1,733,139
Options outstanding, ending balance (in shares)	1,439,328	1,646,607
Weighted Average Grant Date Fair Value	'	'
Weighted average grant date fair value, beginning balance (in dollars per share)	$6.66	$6.52
Weighted average grant date fair value, options regranted (modified) (in dollars per share)	'	$6.76
Weighted average grant date fair value, options exercised (in dollars per share)	$3.81	$5.24
Weighted average grant date fair value, options cancelled (modified) (in dollars per share)	'	$6.76
Weighted average grant date fair value, ending balance (in dollars per share)	$6.93	$6.75
Weighted Average Grant Date Exercise Price	'	'
Weighted average grant date exercise price, beginning balance (in dollars per share)	$18.88	$20.69
Weighted average grant date exercise price, options regranted (modified) (in dollars per share)	'	$19.02
Weighted average grant date exercise price, options exercised (in dollars per share)	$25.10	$23.58
Weighted average grant date exercise price, options cancelled (modified) (in dollars per share)	'	$20.12
Weighted average grant date exercise price, ending balance (in dollars per share)	$18.30	$18.94

Stock_plans_Other_awards_activ

Stock plans (Other awards activity) (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Restricted share awards	'	'
Activities	'	'
Beginning balance (in shares)	2,684,745	2,170,547
Granted (in shares)	925,610	1,580,117
Vested (in shares)	-769,971	-930,296
Forfeited (in shares)	-69,117	-110,912
Ending balance (in shares)	2,771,267	2,709,456
Weighted average grant date fair value	'	'
Weighted average grant date fair value, beginning balance (in dollars per share)	$33.74	$29.24
Weighted average grant date fair value, granted (in dollars per share)	$37.33	$36.06
Weighted average grant date fair value, vested (in dollars per share)	$31.47	$28.08
Weighted average grant date fair value, forfeited (in dollars per share)	$36.28	$28.34
Weighted average grant date fair value, ending balance (in dollars per share)	$35.50	$33.65
Restricted share units	'	'
Activities	'	'
Beginning balance (in shares)	66,518	47,238
Granted (in shares)	53,025	36,635
Vested (in shares)	-18,325	-21,814
Issued in lieu of cash dividends (in shares)	1,479	3,924
Ending balance (in shares)	102,697	65,983
Weighted average grant date fair value	'	'
Weighted average grant date fair value, beginning balance (in dollars per share)	$33.74	$29.61
Weighted average grant date fair value, granted (in dollars per share)	$38.10	$36.11
Weighted average grant date fair value, vested (in dollars per share)	$30.71	$28.17
Weighted average grant date fair value, issued in lieu of cash dividends (in dollars per share)	$34.19	$30.29
Weighted average grant date fair value, ending balance (in dollars per share)	$36.54	$33.74
Performance shares	'	'
Activities	'	'
Beginning balance (in shares)	101,820	220,845
Granted (in shares)	52,639	38,386
Vested (in shares)	-32,746	-39,094
Forfeited (in shares)	'	-18,701
Conversion adjustment (in shares)	-15,344	-99,616
Ending balance (in shares)	106,369	101,820
Weighted average grant date fair value	'	'
Weighted average grant date fair value, beginning balance (in dollars per share)	$33.56	$31.81
Weighted average grant date fair value, granted (in dollars per share)	$37.33	$36.11
Weighted average grant date fair value, vested (in dollars per share)	$32.62	$28.70
Weighted average grant date fair value, forfeited (in dollars per share)	'	$31.05
Weighted average grant date fair value, conversion adjustment (in dollars per share)	$31.38	$33.05
Weighted average grant date fair value, ending balance (in dollars per share)	$36.03	$33.56

Stock_plans_Components_of_shar

Stock plans (Components of share compensation expenses) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Total share compensation expenses	'	'	'	'
Share compensation expenses	$8,764	$10,527	$24,252	$19,483
Restricted share awards	'	'	'	'
Total share compensation expenses	'	'	'	'
Share compensation expenses	8,180	10,041	23,101	20,035
Restricted share units	'	'	'	'
Total share compensation expenses	'	'	'	'
Share compensation expenses	269	168	602	419
Performance shares	'	'	'	'
Total share compensation expenses	'	'	'	'
Share compensation expenses	$315	$318	$549	($971)

Stock_plans_Narrative_Details

Stock plans (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Stock plans (other details)	'	'	'	'	'
Number of shares reserved for issuance under the LTIP and STIP	13,126,896	'	13,126,896	'	'
Remaining number of shares reserved for issuance	1,018,998	'	1,018,998	'	'
Share compensation expenses	$8,764	$10,527	$24,252	$19,483	'
Options	'	'	'	'	'
Stock plans (other details)	'	'	'	'	'
Life of options	'	'	'10 years	'	'
Share compensation expenses	0	0	0	0	'
Unrecognized share compensation expenses	0	0	0	0	'
Restricted share awards	'	'	'	'	'
Stock plans (other details)	'	'	'	'	'
Share compensation expenses	8,180	10,041	23,101	20,035	'
Unrecognized share compensation expenses	77,920	'	77,920	'	69,219
Weighted average period of recognizing share based compensation expenses	'	'	'3 years 0 months 0 days	'3 years 2 months 12 days	'
Restricted share units	'	'	'	'	'
Stock plans (other details)	'	'	'	'	'
Share compensation expenses	269	168	602	419	'
Unrecognized share compensation expenses	3,038	'	3,038	'	1,678
Weighted average period of recognizing share based compensation expenses	'	'	'3 years 3 months 29 days	'3 years 4 months 24 days	'
Performance shares	'	'	'	'	'
Stock plans (other details)	'	'	'	'	'
Share compensation expenses	315	318	549	-971	'
Unrecognized share compensation expenses	$2,527	'	$2,527	'	$1,642
Weighted average period of recognizing share based compensation expenses	'	'	'2 years 3 months 18 days	'2 years 0 months 4 days	'
Performance share awards performance period	'	'	'3 years	'	'

Debt_and_financing_arrangement2

Debt and financing arrangements (Schedule of finance structure) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instruments [Line Items]	'	'
Debt instrument, commitment	$850,153	$851,616
Debt instrument, outstanding	789,953	791,416
Debt instrument, drawn	787,232	788,614
Credit facility, commitment	1,605,000	1,599,800
Credit facility, issued and outstanding	682,091	751,250
Total debt and financing arrangements, commitment	2,455,153	2,451,416
Total debt and financing arrangements, outstanding	1,472,044	1,542,666
$400,000 syndicated unsecured letter of credit facility	'	'
Debt Instruments [Line Items]	'	'
Credit facility, commitment	400,000	400,000
Credit facility, issued and outstanding	0	0
$525,000 syndicated secured letter of credit facility	'	'
Debt Instruments [Line Items]	'	'
Credit facility, commitment	525,000	525,000
Credit facility, issued and outstanding	301,340	358,567
$200,000 secured bi-lateral letter of credit facility	'	'
Debt Instruments [Line Items]	'	'
Credit facility, commitment	200,000	200,000
Credit facility, issued and outstanding	19,743	16,726
Talbot FAL facility	'	'
Debt Instruments [Line Items]	'	'
Credit facility, commitment	25,000	25,000
Credit facility, issued and outstanding	25,000	25,000
PaCRe Senior secured letter of credit facility	'	'
Debt Instruments [Line Items]	'	'
Credit facility, commitment	10,000	10,000
Credit facility, issued and outstanding	294	294
AlphaCat Re secured letter of credit facility	'	'
Debt Instruments [Line Items]	'	'
Credit facility, commitment	30,000	24,800
Credit facility, issued and outstanding	30,000	24,800
IPC bi-lateral facility	'	'
Debt Instruments [Line Items]	'	'
Credit facility, commitment	40,000	40,000
Credit facility, issued and outstanding	16,975	20,177
$375,000 Flagstone bi-lateral facility	'	'
Debt Instruments [Line Items]	'	'
Credit facility, commitment	375,000	375,000
Credit facility, issued and outstanding	288,739	305,686
Total debentures payable	'	'
Debt Instruments [Line Items]	'	'
Debt instrument, commitment	600,153	601,616
Debt instrument, outstanding	539,953	541,416
Debt instrument, drawn	539,953	541,416
2006 Junior Subordinated Deferrable Debentures	'	'
Debt Instruments [Line Items]	'	'
Debt instrument, commitment	150,000	150,000
Debt instrument, outstanding	150,000	150,000
Debt instrument, drawn	150,000	150,000
2007 Junior Subordinated Deferrable Debentures	'	'
Debt Instruments [Line Items]	'	'
Debt instrument, commitment	200,000	200,000
Debt instrument, outstanding	139,800	139,800
Debt instrument, drawn	139,800	139,800
Flagstone 2006 Junior Subordinated Deferrable Debentures	'	'
Debt Instruments [Line Items]	'	'
Debt instrument, commitment	136,403	137,866
Debt instrument, outstanding	136,403	137,866
Debt instrument, drawn	136,403	137,866
Flagstone 2007 Junior Subordinated Deferrable Debentures	'	'
Debt Instruments [Line Items]	'	'
Debt instrument, commitment	113,750	113,750
Debt instrument, outstanding	113,750	113,750
Debt instrument, drawn	113,750	113,750
2010 Senior Notes Due 2040	'	'
Debt Instruments [Line Items]	'	'
Debt instrument, commitment	250,000	250,000
Debt instrument, outstanding	250,000	250,000
Debt instrument, drawn	$247,279	$247,198

Debt_and_financing_arrangement3

Debt and financing arrangements (Summary of notes and debentures) (Details) (USD $)

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

In Thousands, unless otherwise specified

2006 Junior Subordinated Deferrable Debentures

2006 Junior Subordinated Deferrable Debentures

Flagstone 2006 Junior Subordinated Deferrable Interest Notes

Flagstone 2006 Junior Subordinated Deferrable Interest Notes

2007 Junior Subordinated Deferrable Debentures

2007 Junior Subordinated Deferrable Debentures

2010 Senior Notes Due 2040

2010 Senior Notes Due 2040

Debt Information At Issuance [Member]

Debt Information At Issuance [Member]

Debt Information At Issuance [Member]

Debt Information At Issuance [Member]

Debt Information At Issuance [Member]

Debt Information At Issuance [Member]

Debt Information At Issuance [Member]

Debt Information At Issuance [Member]

Debt Information At Issuance [Member]

Debt Outstanding [Member]

Debt Outstanding [Member]

Debt Outstanding [Member]

Debt Outstanding [Member]

Debt Outstanding [Member]

Debt Outstanding [Member]

2006 Junior Subordinated Deferrable Debentures

Flagstone 2006 Junior Subordinated Deferrable Interest Notes

Flagstone 2006 Junior Subordinated Deferrable Interest Notes

2007 Junior Subordinated Deferrable Debentures

Flagstone 2007 Due July 30 2037

Flagstone 2007 Due July 30 2037

Flagstone 2007 Debt Due September 15 2037

Flagstone 2007 Debt Due September 15 2037

2010 Senior Notes Due 2040

2006 Junior Subordinated Deferrable Debentures

Flagstone 2006 Junior Subordinated Deferrable Interest Notes

2007 Junior Subordinated Deferrable Debentures

Flagstone 2007 Due July 30 2037

Flagstone 2007 Debt Due September 15 2037

2010 Senior Notes Due 2040

London Interbank Offered Rate (LIBOR) [Member]

London Interbank Offered Rate (LIBOR) [Member]

London Interbank Offered Rate (LIBOR) [Member]

Debt Instruments [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Issuance Date

'

'

'

'

'

'

'

'

'

'

15-Jun-06

23-Aug-06

'

21-Jun-07

8-Jun-07

'

20-Sep-07

'

26-Jan-10

15-Jun-06

23-Aug-06

21-Jun-07

8-Jun-07

20-Sep-07

26-Jan-10

Debt instrument, commitment

$850,153

$851,616

$150,000

$150,000

$136,403

$137,866

$200,000

$200,000

$250,000

$250,000

$150,000

$136,403

'

$200,000

$88,750

'

$25,000

'

$250,000

$150,000

$136,403

$200,000

$88,750

$25,000

$250,000

Debt Instrument, Maturity Date

'

'

'

'

'

'

'

'

'

'

15-Jun-36

15-Sep-36

'

15-Jun-37

30-Jul-37

'

15-Sep-37

'

26-Jan-40

15-Jun-36

15-Sep-36

15-Jun-37

30-Jul-37

15-Sep-37

26-Jan-40

Debt Instrument, Interest Rate, Stated Percentage

'

'

'

'

'

'

'

'

'

'

9.07%

[1]

'

'

8.48%

[1]

'

'

'

'

8.88%

[1]

'

'

'

'

'

8.88%

[1]

Debt Instrument, Basis Spread on Variable Rate

'

'

'

'

'

'

'

'

'

'

'

'

3.54%

[2]

'

'

3.00%

[2]

'

3.10%

[2]

'

'

'

'

'

'

'

Debt Instrument, Interest Rate, Effective Percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5.83%

[3]

6.46%

[3]

5.18%

[3]

5.90%

[3]

5.98%

[3]

'

Debt Instrument, Frequency of Periodic Payment

'

'

'

'

'

'

'

'

'

'

'Quarterly

'Quarterly

'

'Quarterly

'Quarterly

'

'Quarterly

'

'Semi-annually in arrears

'Quarterly

'Quarterly

'Quarterly

'Quarterly

'Quarterly

'Semi-annually in arrears

[1]

Fixed interest rate.

[2]

Variable interest rate is the three-month LIBOR, reset quarterly, plus spread as noted in the table.

[3]

Interest rate has been fixed as a result of interest rate swap contracts entered into by the Company.

Debt_and_financing_arrangement4

Debt and financing arrangements (Components of finance expenses) (Details) (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Debt Instruments [Line Items]	'		'		'		'
Financing Interest Expense	$15,354		$15,317		$47,380		$47,252
Credit facilities	'		'		'		'
Debt Instruments [Line Items]	'		'		'		'
Financing Interest Expense	1,295		1,248		4,225		5,001
Bank charges	'		'		'		'
Debt Instruments [Line Items]	'		'		'		'
Financing Interest Expense	88		187		303		420
AlphaCat ILS fund fees	'		'		'		'
Debt Instruments [Line Items]	'		'		'		'
Financing Interest Expense	384	[1]	78	[1]	2,030	[1]	2,406	[1]
Talbot FAL facility	'		'		'		'
Debt Instruments [Line Items]	'		'		'		'
Financing Interest Expense	-169		32		-165		95
2006 Junior Subordinated Deferrable Debentures	'		'		'		'
Debt Instruments [Line Items]	'		'		'		'
Financing Interest Expense	2,235		2,235		6,633		6,633
2007 Junior Subordinated Deferrable Debentures	'		'		'		'
Debt Instruments [Line Items]	'		'		'		'
Financing Interest Expense	1,848		1,848		5,492		5,492
Flagstone 2006 Junior Subordinated Deferrable Debentures	'		'		'		'
Debt Instruments [Line Items]	'		'		'		'
Financing Interest Expense	2,269		2,285		6,736		5,988
Flagstone 2007 Junior Subordinated Deferrable Debentures	'		'		'		'
Debt Instruments [Line Items]	'		'		'		'
Financing Interest Expense	1,807		1,807		5,335		4,426
2010 Senior Notes Due 2040	'		'		'		'
Debt Instruments [Line Items]	'		'		'		'
Financing Interest Expense	$5,597		$5,597		$16,791		$16,791
[1]	Includes finance expenses incurred by AlphaCat Managers, Ltd. in relation to fund raising for the AlphaCat ILS funds, AlphaCat 2014 and AlphaCat 2013.

Debt_and_financing_arrangement5

Debt and financing arrangements (Narrative) (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Senior Notes and Junior Debentures	'	'
Long-term Debt	$539,953	$541,416
Credit Facilities	'	'
Credit facility, commitment	1,605,000	1,599,800
Credit facility, issued and outstanding	682,091	751,250
Credit Facilities	'	'
Credit Facilities	'	'
Minimum level of consolidated net worth	2,600,000	'
Percent of consolidated net income quarterly increase under covenant	50.00%	'
Percent of any net proceeds from issuance of common shares	50.00%	'
Ratio consolidated total debt to net worth under covenant	'0.35:1.00	'
Four-year syndicated unsecured credit facility	'	'
Credit Facilities	'	'
Credit facility, commitment	400,000	400,000
Credit facility, issued and outstanding	0	0
Letter of credit facility period	'4 years	'
Aggregate commitments, maximum	500,000	'
Line of credit facility initiation date	9-Mar-12	'
Four-year syndicated secured credit facility	'	'
Credit Facilities	'	'
Credit facility, commitment	525,000	525,000
Credit facility, issued and outstanding	301,340	358,567
Letter of credit facility period	'4 years	'
Aggregate commitments, maximum	700,000	'
Line of credit facility initiation date	9-Mar-12	'
Talbot FAL Facility	'	'
Credit Facilities	'	'
Credit facility, commitment	25,000	25,000
Credit facility, issued and outstanding	25,000	25,000
IPC bi-lateral facility	'	'
Credit Facilities	'	'
Credit facility, commitment	40,000	40,000
Credit facility, issued and outstanding	16,975	20,177
$200,000 secured bi-lateral letter of credit facility	'	'
Credit Facilities	'	'
Credit facility, commitment	200,000	200,000
Credit facility, issued and outstanding	19,743	16,726
PaCRe Senior secured letter of credit facility	'	'
Credit Facilities	'	'
Credit facility, commitment	10,000	10,000
Credit facility, issued and outstanding	294	294
AlphaCat Re secured letter of credit facility	'	'
Credit Facilities	'	'
Credit facility, commitment	30,000	24,800
Credit facility, issued and outstanding	30,000	24,800
$375,000 Flagstone bi-lateral facility	'	'
Credit Facilities	'	'
Credit facility, commitment	375,000	375,000
Credit facility, issued and outstanding	288,739	305,686
2010 Senior Notes Due 2040	'	'
Senior Notes and Junior Debentures	'	'
Long-term Debt	250,000	'
2010 Senior Notes Due 2040 | Maximum	'	'
Senior Notes and Junior Debentures	'	'
Debt Instrument Redemption Required Notice Period	'60 days	'
2010 Senior Notes Due 2040 | Minimum	'	'
Senior Notes and Junior Debentures	'	'
Debt Instrument Redemption Required Notice Period	'30 days	'
Junior subordinated deeferrable debentures	'	'
Senior Notes and Junior Debentures	'	'
Long-term Debt	$539,953	'
Debt Instrument Redemption Period Duration	'5 years	'

Accumulated_other_comprehensiv2

Accumulated other comprehensive (loss) income (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Balance, beginning of period	'	'	($617)	'
Other comprehensive (loss) income	-5,198	4,390	-2,121	-5,209
Balance, end of period	-2,738	'	-2,738	'
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Translation Adjustment [Member]	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Balance, beginning of period	2,460	-8,262	-617	-2,953
Amounts reclassified to retained earnings	0	0	0	4,290
Other comprehensive (loss) income	-5,198	4,390	-2,121	-5,209
Balance, end of period	($2,738)	($3,872)	($2,738)	($3,872)

Commitments_and_contingencies_1

Commitments and contingencies (Investment portfolio) (Details)	9 Months Ended
	Sep. 30, 2014
Shareholders' Equity | Concentrations of credit risk	'
Concentrations Of Credit Risk [Abstract]	'
Maximum aggregate exposure to risk assets, allowed as a percentage of Shareholder's Equity	35.00%
Investment portfolio excluding government and agency securities | Concentrations of credit risk	'
Concentrations Of Credit Risk [Abstract]	'
Maximum aggregate exposure to single issuer, allowed	3.50%
Aggregate exposure to single issuer, actual	0.90%
Bank loan portfolio | Concentrations of credit risk	'
Concentrations Of Credit Risk [Abstract]	'
Total investment portfolio, fair value	6.80%
Investment portfolio excluding bank loans | Concentrations of credit risk	'
Concentrations Of Credit Risk [Abstract]	'
Minimum credit rating of any security purchased	'Baa3/BBB-
Holding in aggregate market value permitted with written pre-authorization	10.00%
Percent of investment portfolio with a credit rating below the minimum required credit rating of Baa3/BBB-	1.70%
Weighted Average [Member] | Shareholders' Equity	'
Concentrations Of Credit Risk [Abstract]	'
Minimum credit rating of any security purchased	'A+

Commitments_and_contingencies_2

Commitments and contingencies (Lloyd's syndicate) (Details)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014
In Thousands, unless otherwise specified	USD ($)	USD ($)	Lloyd's Syndicate 1183	Lloyd's Syndicate 1183	20114 Underwriting year	2013 Underwriting year
			USD ($)	GBP (£)	Lloyd's Syndicate 1183	Lloyd's Syndicate 1183
					USD ($)	USD ($)
Components Of Required Capital [Abstract]	'	'	'	'	'	'
Credit facility, commitment	$1,605,000	$1,599,800	'	'	$25,000	$25,000
Required Capital Group Funds	'	'	'	'	450,000	403,700
Cash, investments and letters of credit amount	'	'	'	'	475,000	428,700
Funds at Lloyd's and Lloyd's Central Fund	'	'	'	'	'	'
Maximum premium levies assessable, percent	'	'	3.00%	3.00%	'	'
Estimated underwriting capacity	'	'	'	625,000	'	'
Exchange rate	'	'	'£1 equals $1.6195	'£1 equals $1.6195	'	'
Maximum premium levies assessable, amount	'	'	$30,366	'	'	'

Commitments_and_contingencies_3

Commitments and contingencies (Aquiline commitment) (Details) (Aquiline Capital Partners II GP Offshore Ltd, USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Aquiline Capital Partners II GP Offshore Ltd	'	'
Related Party Transaction [Line Items]	'	'
Total capital commitment	$50,000	'
Remaining capital commitment	$17,890	$17,890

Commitments_and_contingencies_4

Commitments and contingencies (Other investment commitments) (Details) (Investment commitment [Member], USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	funds
Investment commitment [Member]	'	'
Other Commitments [Line Items]	'	'
Other Investments Number Of Funds	5	'
Contractual Obligation	$105,000	$5,045
Remaining Commitment	$79,259	'

Related_party_transactions_Det

Related party transactions (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Related Party Transaction [Line Items]	'	'	'	'	'
Reinsurance Payable	$141,482	'	$141,482	'	$154,874
Aquiline Capital Partners LLC	'	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'	'
Shares owned by related party	3,446,643	'	3,446,643	'	'
Warrants to purchase shares	2,756,088	'	2,756,088	'	'
Related Parties Number Of Employees	'	'	2	'	'
Group Ark Insurance Holdings Ltd	'	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'	'
Gross premiums written	246	0	2,190	2,848	'
Premiums receivable	733	'	733	'	238
Reinsurance premiums ceded	127	23	127	23	'
Related Party Transaction Reinsurance Balances Payable	4	'	4	'	4
Loss reserves recoverable	2,005	'	2,005	'	3,698
Earned premium adjustments	694	718	1,653	2,147	'
Conning Inc	'	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'	'
Investment management fees	-7	165	219	396	'
Accounts payable and accrued expenses	239	'	239	'	283
Aquiline Capital Partners II GP Offshore Ltd	'	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'	'
Accounts payable and accrued expenses	0	'	0	'	0
Percentage of Assignor's interest assumed	'	'	100.00%	'	'
Total capital commitment	'	'	50,000	'	'
Partnership fees incurred	0	505	0	625	'
Capital contributions	$0	$6,185	$0	$13,089	'

Earnings_per_share_Details

Earnings per share (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Basic earnings per share	'	'	'	'
Net income	($13,397)	$229,063	$381,172	$419,503
Loss (income) attributable to noncontrolling interest	53,069	-45,694	-25,745	17,831
Net income available to Validus	39,672	183,369	355,427	437,334
Less: Dividends and distributions declared on outstanding warrants	-1,552	-1,552	-4,656	-17,662
Income available to common shareholders	38,120	181,817	350,771	419,672
Weighted average number of common shares outstanding	90,593,329	99,834,563	91,665,950	103,451,396
Basic earnings per share available to common shareholders	$0.42	$1.82	$3.83	$4.06
Earnings per diluted share	'	'	'	'
Net income	-13,397	229,063	381,172	419,503
Loss (income) attributable to noncontrolling interest	53,069	-45,694	-25,745	17,831
Net income available to Validus	39,672	183,369	355,427	437,334
less: Dividends and distributions declared on outstanding warrants	-1,552	0	0	-17,662
Income available to common shareholders	$38,120	$183,369	$355,427	$419,672
Weighted average number of common shares outstanding	90,593,329	99,834,563	91,665,950	103,451,396
Weighted average number of diluted common shares outstanding	91,939,610	103,613,766	95,937,641	105,264,913
Earnings per diluted share available to common shareholders	$0.41	$1.77	$3.70	$3.99
Other details:	'	'	'	'
Anti-dilutive securities excluded from the calculation of diluted earnings per share	4,712	125,728	235,460	464,516
Warrants	'	'	'	'
Earnings per diluted share	'	'	'	'
Weighted average number of diluted common shares outstanding, aggregate	0	2,606,669	2,747,399	0
Stock options	'	'	'	'
Earnings per diluted share	'	'	'	'
Weighted average number of diluted common shares outstanding, aggregate	760,267	782,158	752,145	1,090,298
Unvested restricted shares	'	'	'	'
Earnings per diluted share	'	'	'	'
Weighted average number of diluted common shares outstanding, aggregate	586,014	390,376	772,147	723,219

Segment_information_Details

Segment information (Details) (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Dec. 31, 2013
Underwriting income	'		'		'		'		'
Gross premiums written	$358,974		$356,760		$2,026,639		$2,163,833		'
Reinsurance premiums ceded	-30,137		-39,415		-275,610		-348,027		'
Net premiums written	328,837		317,345		1,751,029		1,815,806		'
Change in unearned premiums	165,859		213,943		-307,373		-205,999		'
Net premiums earned	494,696		531,288		1,443,656		1,609,807		'
Underwriting deductions	'		'		'		'		'
Losses and loss expenses	224,125		177,965		545,541		587,780		'
Policy acquisition costs	86,404		94,900		251,006		275,663		'
General and administrative expenses	83,319		81,089		231,606		232,335		'
Share compensation expenses	8,764		10,527		24,252		19,483		'
Total underwriting deductions	402,612		364,481		1,052,405		1,115,261		'
Underwriting income (loss)	92,084		166,807		391,251		494,546		'
Net investment income	25,261		20,009		69,909		71,868		'
Other (loss) income	-4,080		-2,806		14,985		4,297		'
Finance expenses	-15,354		-15,317		-47,380		-47,252		'
Operating income (loss) before taxes, income from operating affiliates and (income) attributable to operating affiliate investors	97,911		168,693		428,765		523,459		'
Tax benefit (expense)	953		-5		-398		220		'
Income from operating affilates	3,761		1,463		13,580		8,779		'
(Income) attributable to operating affiliate investors	-25,807		-11,815		-82,833		-42,156		'
Net operating income (loss)	76,818		158,336		359,114		490,302		'
Net realized gains on investments	4,595		-6,320		16,193		-1,190		'
Change in net unrealized gains on investments	-84,974	[1]	69,967	[1]	16,146	[1]	-78,618	[1]	'
Income from investment affiliate	1,754		1,044		7,881		4,274		'
Foreign exchange gains (losses)	-11,441		6,036		-14,761		4,735		'
Transaction expenses	-149	[2]	0		-3,401	[2]	0		'
Net (loss) income	-13,397		229,063		381,172		419,503		'
Net loss (income) attributable to noncontrolling interest	53,069		-45,694		-25,745		17,831		'
Net income (loss) available (attributable) to Validus	39,672		183,369		355,427		437,334		'
Selected ratios:	'		'		'		'		'
Net Premium To Gross Premium Ratio	91.60%	[3]	89.00%	[3]	86.40%	[3]	83.90%	[3]	'
Losses and loss expenses	45.30%	[3]	33.50%	[3]	37.80%	[3]	36.50%	[3]	'
Policy acquisition costs	17.50%	[3]	17.90%	[3]	17.40%	[3]	17.20%	[3]	'
General and Administrative Expense Ratio	18.60%	[3],[4]	17.20%	[3],[4]	17.70%	[3],[4]	15.60%	[3],[4]	'
Underwriting Expense Ratio	36.10%	[3]	35.10%	[3]	35.10%	[3]	32.80%	[3]	'
Combined ratio	81.40%	[3]	68.60%	[3]	72.90%	[3]	69.30%	[3]	'
Total assets	10,053,050		10,317,368		10,053,050		10,317,368		9,846,432
Operating Segments [Member] | Validus Re Segment	'		'		'		'		'
Underwriting income	'		'		'		'		'
Gross premiums written	114,897		130,925		1,104,169		1,232,272		'
Reinsurance premiums ceded	-10,899		-13,006		-184,074		-226,292		'
Net premiums written	103,998		117,919		920,095		1,005,980		'
Change in unearned premiums	122,712		157,873		-233,271		-122,303		'
Net premiums earned	226,710		275,792		686,824		883,677		'
Underwriting deductions	'		'		'		'		'
Losses and loss expenses	102,005		62,250		247,848		319,298		'
Policy acquisition costs	36,177		47,662		106,547		142,195		'
General and administrative expenses	18,522		19,785		53,757		69,649		'
Share compensation expenses	2,582		2,479		7,126		5,421		'
Total underwriting deductions	159,286		132,176		415,278		536,563		'
Underwriting income (loss)	67,424		143,616		271,546		347,114		'
Net investment income	20,762		15,628		56,285		61,770		'
Other (loss) income	-6,827		-1,892		912		11,237		'
Finance expenses	-3,622		-3,640		-11,131		-12,133		'
Operating income (loss) before taxes, income from operating affiliates and (income) attributable to operating affiliate investors	77,737		153,712		317,612		407,988		'
Tax benefit (expense)	1,058		143		1,176		1,755		'
Income from operating affilates	0		0		0		0		'
(Income) attributable to operating affiliate investors	0		0		0		0		'
Net operating income (loss)	78,795		153,855		318,788		409,743		'
Net realized gains on investments	1,641		-10,137		5,411		-5,790		'
Change in net unrealized gains on investments	-20,149		23,144		5,279		-36,883		'
Income from investment affiliate	1,754		1,044		7,881		4,274		'
Foreign exchange gains (losses)	-6,056		2,168		-9,384		7,448		'
Net (loss) income	55,985		170,074		327,975		378,792		'
Net loss (income) attributable to noncontrolling interest	0		0		0		0		'
Net income (loss) available (attributable) to Validus	55,985		170,074		327,975		378,792		'
Selected ratios:	'		'		'		'		'
Net Premium To Gross Premium Ratio	90.50%	[3]	90.10%	[3]	83.30%	[3]	81.60%	[3]	'
Losses and loss expenses	45.00%	[3]	22.60%	[3]	36.10%	[3]	36.10%	[3]	'
Policy acquisition costs	16.00%	[3]	17.30%	[3]	15.50%	[3]	16.10%	[3]	'
General and Administrative Expense Ratio	9.30%	[3],[4]	8.10%	[3],[4]	8.90%	[3],[4]	8.50%	[3],[4]	'
Underwriting Expense Ratio	25.30%	[3]	25.40%	[3]	24.40%	[3]	24.60%	[3]	'
Combined ratio	70.30%	[3]	48.00%	[3]	60.50%	[3]	60.70%	[3]	'
Total assets	4,716,426		5,854,354		4,716,426		5,854,354		'
Operating Segments [Member] | AlphaCat Segment	'		'		'		'		'
Underwriting income	'		'		'		'		'
Gross premiums written	6,936		3,481		135,073		146,757		'
Reinsurance premiums ceded	-648		-525		-4,348		-525		'
Net premiums written	6,288		2,956		130,725		146,232		'
Change in unearned premiums	28,850		34,210		-32,444		-46,459		'
Net premiums earned	35,138		37,166		98,281		99,773		'
Underwriting deductions	'		'		'		'		'
Losses and loss expenses	3,738		15,615		-7,155		16,928		'
Policy acquisition costs	3,378		3,787		9,414		10,011		'
General and administrative expenses	7,719		5,728		15,627		13,757		'
Share compensation expenses	179		152		330		314		'
Total underwriting deductions	15,014		25,282		18,216		41,010		'
Underwriting income (loss)	20,124		11,884		80,065		58,763		'
Net investment income	837		967		2,546		2,821		'
Other (loss) income	5,980		3,791		21,482		17,439		'
Finance expenses	-385		-80		-2,039		-4,273		'
Operating income (loss) before taxes, income from operating affiliates and (income) attributable to operating affiliate investors	26,556		16,562		102,054		74,750		'
Tax benefit (expense)	0		0		0		0		'
Income from operating affilates	3,761		1,463		13,580		8,779		'
(Income) attributable to operating affiliate investors	-25,807		-11,815		-82,833		-42,156		'
Net operating income (loss)	4,510		6,210		32,801		41,373		'
Net realized gains on investments	2,563		4,084		10,230		4,084		'
Change in net unrealized gains on investments	-60,253		44,145		15,706		-31,029		'
Income from investment affiliate	0		0		0		0		'
Foreign exchange gains (losses)	-51		388		-204		-663		'
Net (loss) income	-53,231		54,827		58,533		13,765		'
Net loss (income) attributable to noncontrolling interest	53,069		-45,694		-25,745		17,831		'
Net income (loss) available (attributable) to Validus	-162		9,133		32,788		31,596		'
Selected ratios:	'		'		'		'		'
Net Premium To Gross Premium Ratio	90.70%	[3]	84.90%	[3]	96.80%	[3]	99.60%	[3]	'
Losses and loss expenses	10.60%	[3]	42.00%	[3]	-7.30%	[3]	17.00%	[3]	'
Policy acquisition costs	9.60%	[3]	10.20%	[3]	9.60%	[3]	10.00%	[3]	'
General and Administrative Expense Ratio	22.50%	[3],[4]	15.80%	[3],[4]	16.20%	[3],[4]	14.10%	[3],[4]	'
Underwriting Expense Ratio	32.10%	[3]	26.00%	[3]	25.80%	[3]	24.10%	[3]	'
Combined ratio	42.70%	[3]	68.00%	[3]	18.50%	[3]	41.10%	[3]	'
Total assets	1,688,191		1,446,941		1,688,191		1,446,941		'
Operating Segments [Member] | Talbot Segment	'		'		'		'		'
Underwriting income	'		'		'		'		'
Gross premiums written	245,685		246,468		854,324		855,516		'
Reinsurance premiums ceded	-27,134		-49,998		-154,115		-191,922		'
Net premiums written	218,551		196,470		700,209		663,594		'
Change in unearned premiums	14,297		21,860		-41,658		-37,237		'
Net premiums earned	232,848		218,330		658,551		626,357		'
Underwriting deductions	'		'		'		'		'
Losses and loss expenses	118,382		100,100		304,848		251,554		'
Policy acquisition costs	47,862		44,899		138,383		127,092		'
General and administrative expenses	37,709		37,402		107,031		100,506		'
Share compensation expenses	2,990		2,992		8,434		6,754		'
Total underwriting deductions	206,943		185,393		558,696		485,906		'
Underwriting income (loss)	25,905		32,937		99,855		140,451		'
Net investment income	4,965		4,395		14,322		13,496		'
Other (loss) income	109		73		384		564		'
Finance expenses	162		-107		68		-256		'
Operating income (loss) before taxes, income from operating affiliates and (income) attributable to operating affiliate investors	31,141		37,298		114,629		154,255		'
Tax benefit (expense)	332		-513		-902		-1,184		'
Income from operating affilates	0		0		0		0		'
(Income) attributable to operating affiliate investors	0		0		0		0		'
Net operating income (loss)	31,473		36,785		113,727		153,071		'
Net realized gains on investments	391		-267		552		516		'
Change in net unrealized gains on investments	-3,097		2,678		2,159		-10,706		'
Income from investment affiliate	0		0		0		0		'
Foreign exchange gains (losses)	-7,114		4,238		-5,897		-1,877		'
Net (loss) income	21,653		43,434		110,541		141,004		'
Net loss (income) attributable to noncontrolling interest	0		0		0		0		'
Net income (loss) available (attributable) to Validus	21,653		43,434		110,541		141,004		'
Selected ratios:	'		'		'		'		'
Net Premium To Gross Premium Ratio	89.00%	[3]	79.70%	[3]	82.00%	[3]	77.60%	[3]	'
Losses and loss expenses	50.80%	[3]	45.80%	[3]	46.30%	[3]	40.20%	[3]	'
Policy acquisition costs	20.60%	[3]	20.60%	[3]	21.00%	[3]	20.30%	[3]	'
General and Administrative Expense Ratio	17.50%	[3],[4]	18.50%	[3],[4]	17.50%	[3],[4]	17.10%	[3],[4]	'
Underwriting Expense Ratio	38.10%	[3]	39.10%	[3]	38.50%	[3]	37.40%	[3]	'
Combined ratio	88.90%	[3]	84.90%	[3]	84.80%	[3]	77.60%	[3]	'
Total assets	2,898,755		2,892,477		2,898,755		2,892,477		'
Corporate And Eliminations [Member]	'		'		'		'		'
Underwriting income	'		'		'		'		'
Gross premiums written	-8,544		-24,114		-66,927		-70,712		'
Reinsurance premiums ceded	8,544		24,114		66,927		70,712		'
Net premiums written	0		0		0		0		'
Change in unearned premiums	0		0		0		0		'
Net premiums earned	0		0		0		0		'
Underwriting deductions	'		'		'		'		'
Losses and loss expenses	0		0		0		0		'
Policy acquisition costs	-1,013		-1,448		-3,338		-3,635		'
General and administrative expenses	19,369		18,174		55,191		48,423		'
Share compensation expenses	3,013		4,904		8,362		6,994		'
Total underwriting deductions	21,369		21,630		60,215		51,782		'
Underwriting income (loss)	-21,369		-21,630		-60,215		-51,782		'
Net investment income	-1,303		-981		-3,244		-6,219		'
Other (loss) income	-3,342		-4,778		-7,793		-24,943		'
Finance expenses	-11,509		-11,490		-34,278		-30,590		'
Operating income (loss) before taxes, income from operating affiliates and (income) attributable to operating affiliate investors	-37,523		-38,879		-105,530		-113,534		'
Tax benefit (expense)	-437		365		-672		-351		'
Income from operating affilates	0		0		0		0		'
(Income) attributable to operating affiliate investors	0		0		0		0		'
Net operating income (loss)	-37,960		-38,514		-106,202		-113,885		'
Net realized gains on investments	0		0		0		0		'
Change in net unrealized gains on investments	-1,475		0		-6,998		0		'
Income from investment affiliate	0		0		0		0		'
Foreign exchange gains (losses)	1,780		-758		724		-173		'
Transaction expenses	-149	[2]	'		-3,401	[2]	'		'
Net (loss) income	-37,804		-39,272		-115,877		-114,058		'
Net loss (income) attributable to noncontrolling interest	0		0		0		0		'
Net income (loss) available (attributable) to Validus	-37,804		-39,272		-115,877		-114,058		'
Selected ratios:	'		'		'		'		'
Total assets	$749,678		$123,596		$749,678		$123,596		'
[1]	Includes change in net unrealized gains (losses) and realized gains on investments held by PaCRe in which the Company has an equity interest of 10%. The remaining 90% interest is held by third party investors and is included in the Consolidated Statements of Comprehensive Income as net loss (income) attributable to noncontrolling interest.
[2]	The transaction expenses relate to costs incurred in connection with the acquisition of Western World, which was completed on October 2, 2014. Western World results have not been included in the Company's consolidated results for the three months ended September 30, 2014. Transaction expenses are primarily comprised of legal, financial advisory and audit related services.
[3]	Ratios are based on net premiums earned.
[4]	The general and administrative expense ratio includes share compensation expenses.

Segment_information_Segment_ge

Segment information (Segment geographic) (Details) (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	$358,974		$356,760		$2,026,639		$2,163,833
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	47,000		60,895		558,433		660,658
Percent of gross premiums written	13.10%		17.00%		27.50%		30.60%
Worldwide excluding United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	39,366	[1]	47,586	[1]	186,658	[1]	184,780	[1]
Percent of gross premiums written	10.90%	[1]	13.30%	[1]	9.20%	[1]	8.40%	[1]
Australia and New Zealand	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	3,783		-6,780		28,268		30,795
Percent of gross premiums written	1.10%		-1.90%		1.40%		1.40%
Europe	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	18,382		13,421		92,842		105,131
Percent of gross premiums written	5.10%		3.80%		4.60%		4.90%
Latin America and Caribbean	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	36,866		40,633		103,860		122,693
Percent of gross premiums written	10.30%		11.40%		5.10%		5.70%
Japan	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	2,887		-1,688		44,365		46,887
Percent of gross premiums written	0.80%		-0.50%		2.20%		2.20%
Canada	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	2,538		3,978		11,407		12,775
Percent of gross premiums written	0.70%		1.10%		0.60%		0.60%
Rest of the world	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	27,599	[2]	25,978	[2]	90,945	[2]	88,314	[2]
Percent of gross premiums written	7.70%	[2]	7.30%	[2]	4.50%	[2]	4.10%	[2]
Sub-total, non United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	131,421		123,128		558,345		591,375
Percent of gross premiums written	36.60%		34.50%		27.60%		27.30%
Worldwide including United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	51,275	[1]	46,217	[1]	319,854	[1]	309,225	[1]
Percent of gross premiums written	14.30%	[1]	13.00%	[1]	15.80%	[1]	14.30%	[1]
Other location non-specific	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	129,278	[3]	126,520	[3]	590,007	[3]	602,575	[3]
Percent of gross premiums written	36.00%	[3]	35.50%	[3]	29.10%	[3]	27.80%	[3]
Operating Segments [Member] | Validus Re Segment	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	114,897		130,925		1,104,169		1,232,272
Operating Segments [Member] | Validus Re Segment | United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	28,665		38,881		452,470		542,692
Operating Segments [Member] | Validus Re Segment | Worldwide excluding United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	10,639	[1]	16,973	[1]	80,671	[1]	69,482	[1]
Operating Segments [Member] | Validus Re Segment | Australia and New Zealand	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	610		-9,482		20,025		21,116
Operating Segments [Member] | Validus Re Segment | Europe	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	8,560		4,252		57,884		64,986
Operating Segments [Member] | Validus Re Segment | Latin America and Caribbean	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	12,945		5,902		22,167		5,885
Operating Segments [Member] | Validus Re Segment | Japan	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	1,664		-2,637		41,137		41,939
Operating Segments [Member] | Validus Re Segment | Canada	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	188		1,469		3,508		4,503
Operating Segments [Member] | Validus Re Segment | Rest of the world	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	1,527	[2]	5,641	[2]	23,870	[2]	29,211	[2]
Operating Segments [Member] | Validus Re Segment | Sub-total, non United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	36,133		22,118		249,262		237,122
Operating Segments [Member] | Validus Re Segment | Worldwide including United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	28,747	[1]	29,611	[1]	168,337	[1]	180,621	[1]
Operating Segments [Member] | Validus Re Segment | Other location non-specific	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	21,352	[3]	40,315	[3]	234,100	[3]	271,837	[3]
Operating Segments [Member] | AlphaCat Segment	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	6,936		3,481		135,073		146,757
Operating Segments [Member] | AlphaCat Segment | United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	2,206		2,546		31,160		50,935
Operating Segments [Member] | AlphaCat Segment | Worldwide excluding United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	-81	[1]	0	[1]	7,331	[1]	14,801	[1]
Operating Segments [Member] | AlphaCat Segment | Australia and New Zealand	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	0		33		1,019		2,216
Operating Segments [Member] | AlphaCat Segment | Europe	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	312		377		3,005		2,514
Operating Segments [Member] | AlphaCat Segment | Latin America and Caribbean	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	0		0		0		0
Operating Segments [Member] | AlphaCat Segment | Japan	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	22		0		608		653
Operating Segments [Member] | AlphaCat Segment | Canada	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	0		500		215		818
Operating Segments [Member] | AlphaCat Segment | Rest of the world	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	0	[2]	0	[2]	0	[2]	0	[2]
Operating Segments [Member] | AlphaCat Segment | Sub-total, non United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	253		910		12,178		21,002
Operating Segments [Member] | AlphaCat Segment | Worldwide including United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	4,477	[1]	25	[1]	91,735	[1]	74,820	[1]
Operating Segments [Member] | AlphaCat Segment | Other location non-specific	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	0	[3]	0	[3]	0	[3]	0	[3]
Operating Segments [Member] | Talbot Segment	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	245,685		246,468		854,324		855,516
Operating Segments [Member] | Talbot Segment | United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	17,003		21,573		85,465		77,630
Operating Segments [Member] | Talbot Segment | Worldwide excluding United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	29,781	[1]	34,751	[1]	105,397	[1]	109,562	[1]
Operating Segments [Member] | Talbot Segment | Australia and New Zealand	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	3,312		2,905		7,615		7,930
Operating Segments [Member] | Talbot Segment | Europe	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	9,821		9,778		36,110		41,523
Operating Segments [Member] | Talbot Segment | Latin America and Caribbean	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	24,740		38,084		86,111		124,120
Operating Segments [Member] | Talbot Segment | Japan	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	1,274		1,066		3,404		5,258
Operating Segments [Member] | Talbot Segment | Canada	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	2,430		2,749		8,325		8,790
Operating Segments [Member] | Talbot Segment | Rest of the world	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	27,145	[2]	22,167	[2]	70,702	[2]	62,803	[2]
Operating Segments [Member] | Talbot Segment | Sub-total, non United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	98,503		111,500		317,664		359,986
Operating Segments [Member] | Talbot Segment | Worldwide including United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	18,611	[1]	18,246	[1]	71,147	[1]	63,998	[1]
Operating Segments [Member] | Talbot Segment | Other location non-specific	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	111,568	[3]	95,149	[3]	380,048	[3]	353,902	[3]
Corporate And Eliminations [Member]	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	-8,544		-24,114		-66,927		-70,712
Corporate And Eliminations [Member] | United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	-874		-2,105		-10,662		-10,599
Corporate And Eliminations [Member] | Worldwide excluding United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	-973	[1]	-4,138	[1]	-6,741	[1]	-9,065	[1]
Corporate And Eliminations [Member] | Australia and New Zealand	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	-139		-236		-391		-467
Corporate And Eliminations [Member] | Europe	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	-311		-986		-4,157		-3,892
Corporate And Eliminations [Member] | Latin America and Caribbean	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	-819		-3,353		-4,418		-7,312
Corporate And Eliminations [Member] | Japan	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	-73		-117		-784		-963
Corporate And Eliminations [Member] | Canada	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	-80		-740		-641		-1,336
Corporate And Eliminations [Member] | Rest of the world	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	-1,073	[2]	-1,830	[2]	-3,627	[2]	-3,700	[2]
Corporate And Eliminations [Member] | Sub-total, non United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	-3,468		-11,400		-20,759		-26,735
Corporate And Eliminations [Member] | Worldwide including United States	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	-560	[1]	-1,665	[1]	-11,365	[1]	-10,214	[1]
Corporate And Eliminations [Member] | Other location non-specific	'		'		'		'
Gross premiums written allocated to the territory of coverage exposure	'		'		'		'
Gross premiums written	($3,642)	[3]	($8,944)	[3]	($24,141)	[3]	($23,164)	[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, such as marine and aerospace risks, since these exposures can span multiple geographic areas and, in some instances, are not fixed locations.

Segment_information_Narrative_

Segment information (Narrative) (Details)	9 Months Ended
	Sep. 30, 2014
	segments
Segment Reporting [Abstract]	'
Number of operating segments	3

Subsequent_events_Details

Subsequent events (Details) (USD $)

3 Months Ended

9 Months Ended

3 Months Ended

0 Months Ended

In Thousands, except Per Share data, unless otherwise specified

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Nov. 05, 2014

Nov. 05, 2014

Jun. 23, 2014

Oct. 02, 2014

Common shares

Common shares

Common shares

Common shares

Common shares

Common shares

Common share equivalents

Common share equivalents

Common share equivalents

Subsequent Event

Subsequent Event

Western World Insurance Group, Inc [Member]

Western World Insurance Group, Inc [Member]

Common shares

Common share equivalents

Subsequent Event

Subsequent Event [Line Items]

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Cash dividends declared per share

$0.30

$0.30

$0.90

$2.90

$0.30

$0.30

$0.30

$0.30

$0.30

$0.30

$0.30

$0.30

$0.30

$0.30

$0.30

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Business Acquisition, Date of Acquisition Agreement

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23-Jun-14

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Business Acquisition, Effective Date of Acquisition

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2-Oct-14

Business Combination Purchase Agreement Aggregate Purchase Price

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$690,000