Endurance Specialty (ENH) 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. 03, 2014
Document and Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Entity Registrant Name	'Endurance Specialty Holdings Ltd.	'
Entity Central Index Key	'0001179755	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	44,757,803

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
ASSETS	'	'
Fixed maturity investments, available for sale at fair value (amortized cost: $4,820,169 and $4,802,580 at September 30, 2014 and December 31, 2013, respectively)	$4,871,420	$4,823,964
Short-term investments, available for sale at fair value (amortized cost: $11,843 and $35,029 at September 30, 2014 and December 31, 2013, respectively)	11,844	35,028
Equity securities, available for sale at fair value (cost: $239,487 and $227,828 at September 30, 2014 and December 31, 2013, respectively)	267,728	252,466
Other investments	658,678	617,478
Total investments	5,809,670	5,728,936
Cash and cash equivalents	805,716	845,851
Premiums receivable, net	1,452,228	669,198
Insurance and reinsurance balances receivable	123,432	127,722
Deferred acquisition costs	246,437	186,027
Prepaid reinsurance premiums	414,013	187,209
Reinsurance recoverable on unpaid losses	566,329	593,755
Reinsurance recoverable on paid losses	165,592	164,220
Accrued investment income	23,652	24,104
Goodwill and intangible assets	160,560	165,378
Deferred tax asset	53,403	51,703
Net receivable on sales of investments	84,699	54,910
Other assets	240,087	179,109
Total assets	10,145,818	8,978,122
LIABILITIES	'	'
Reserve for losses and loss expenses	3,897,483	4,002,259
Reserve for unearned premiums	1,552,168	1,018,851
Deposit liabilities	17,521	19,458
Reinsurance balances payable	482,093	181,061
Debt	527,732	527,478
Net payable on purchases of investments	238,038	129,047
Other liabilities	310,329	213,419
Total liabilities	7,025,364	6,091,573
Commitments and contingent liabilities	'	'
SHAREHOLDERS' EQUITY	'	'
Preferred shares, Series A and B, total liquidation preference $430,000 (2013 - $430,000)	17,200	17,200
Common shares, Ordinary - 44,751,174 issued and outstanding (2013 - 44,368,742)	44,751	44,369
Additional paid-in capital	590,330	569,116
Accumulated other comprehensive income	81,299	62,731
Retained earnings	2,386,874	2,193,133
Total shareholders' equity	3,120,454	2,886,549
Total liabilities and shareholders' equity	$10,145,818	$8,978,122

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Available-for-sale Securities [Abstract]	'	'
Fixed maturity investments, available for sale, amortized cost	$4,820,169	$4,802,580
Short-term investments, available for sale, amortized cost	11,843	35,029
Equity securities, available for sale, cost	239,487	227,828
Stockholders' Equity, Number of Shares, Par Value and Other Disclosures [Abstract]	'	'
Preferred stock, aggregate liquidation preference	$430,000	$430,000
Common stock, shares issued	44,751,174	44,368,742
Common stock, shares outstanding	44,751,174	44,368,742

Condensed_Consolidated_Stateme

Condensed Consolidated Statements Of Income And Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues	'	'	'	'
Gross premiums written	$626,110	$544,363	$2,473,050	$2,294,435
Ceded premiums written	-236,004	-149,030	-772,812	-525,566
Net premiums written	390,106	395,333	1,700,238	1,768,869
Change in unearned premiums	124,789	158,212	-307,539	-251,872
Net premiums earned	514,895	553,545	1,392,699	1,516,997
Net investment income	25,357	38,097	105,649	119,870
Net realized and unrealized investment gains (losses)	9,788	-6,640	18,071	9,967
Total other-than-temporary impairment losses	-102	-190	-411	-1,575
Portion of loss recognized in other comprehensive (loss) income	0	0	0	0
Net impairment losses recognized in earnings	-102	-190	-411	-1,575
Other underwriting income (loss)	2,123	-943	-3,939	694
Total revenues	552,061	583,869	1,512,069	1,645,953
Expenses	'	'	'	'
Net losses and loss expenses	290,269	339,036	726,361	917,064
Acquisition expenses	93,392	78,775	244,150	222,279
General and administrative expenses	80,915	67,470	240,576	215,307
Amortization of intangibles	1,623	1,652	4,863	5,378
Net foreign exchange losses	783	2,201	4,066	8,496
Interest expense	13,127	9,048	31,910	27,138
Total expenses	480,109	498,182	1,251,926	1,395,662
Income before income taxes	71,952	85,687	260,143	250,291
Income tax benefit (expense)	4,282	-2,271	3,734	-5,557
Net income	76,234	83,416	263,877	244,734
Preferred dividends	-8,188	-8,188	-24,564	-24,564
Net income available to common and participating common shareholders	68,046	75,228	239,313	220,170
Comprehensive income	'	'	'	'
Net income	76,234	83,416	263,877	244,734
Other comprehensive (loss) income	'	'	'	'
Net unrealized holding (losses) gains on investments arising during the period (net of other-than-temporary impairment losses recognized in other comprehensive (loss) income, reclassification adjustment and applicable deferred income taxes of ($3,358) and $8,582 for the nine months ended September 30, 2014 and 2013, respectively)	-34,357	29,079	26,682	-82,016
Foreign currency translation adjustments	-20,404	8,918	-8,181	-1,057
Reclassification adjustment for net losses on derivative designated as cash flow hedge included in net income	22	22	67	67
Other comprehensive (loss) income	-54,739	38,019	18,568	-83,006
Comprehensive income	$21,495	$121,435	$282,445	$161,728
Per share data	'	'	'	'
Basic earnings per common share	$1.52	$1.70	$5.36	$5.04
Diluted earnings per common share	$1.52	$1.70	$5.36	$5.04
Dividend per common share	$0.34	$0.32	$1.02	$0.96

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements Of Income And Comprehensive Income (Parenthetical) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]	'	'
Other comprehensive (loss) income, net unrealized holding (losses) gains on investments arising during the period, tax	($3,358)	$8,582

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements Of Changes In Shareholders' Equity (USD $)	Total	Preferred Shares [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Cumulative Foreign Currency Translation Adjustments [Member]	Unrealized Holding Gains On Investments, Net Of Deferred Taxes [Member]	Accumulated Derivative Loss On Cash Flow Hedging Instruments [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]
In Thousands
Balance, beginning of period at Dec. 31, 2012	'	$17,200	$43,116	$527,915	$12,676	$141,731	($1,944)	'	$1,969,903
Issuance of common shares, net of forfeitures	'	'	1,452	29,961	'	'	'	'	'
Repurchase of common shares	'	'	-318	-14,266	'	'	'	'	'
Settlement of equity awards	'	'	'	-2,975	'	'	'	'	'
Stock-based compensation expense	'	'	'	19,569	'	'	'	'	'
Foreign currency translation adjustments	-1,057	'	'	'	-1,057	'	'	'	'
Net unrealized holding gains (losses) arising during the period, net of other-than-temporary impairment losses and reclassification adjustment	-82,016	'	'	'	'	-82,016	'	'	'
Net change from current period hedging transactions, net of reclassification adjustment	'	'	'	'	'	'	67	'	'
Net income	244,734	'	'	'	'	'	'	'	244,734
Dividends on preferred shares	-24,564	'	'	'	'	'	'	'	-24,564
Dividends on common shares	'	'	'	'	'	'	'	'	-42,174
Balance, end of period at Sep. 30, 2013	2,839,010	17,200	44,250	560,204	11,619	59,715	-1,877	69,457	2,147,899
Balance, beginning of period at Dec. 31, 2013	2,886,549	17,200	44,369	569,116	18,636	45,950	-1,855	'	2,193,133
Issuance of common shares, net of forfeitures	'	'	382	1,270	'	'	'	'	'
Repurchase of common shares	'	'	0	0	'	'	'	'	'
Settlement of equity awards	'	'	'	-4,039	'	'	'	'	'
Stock-based compensation expense	'	'	'	23,983	'	'	'	'	'
Foreign currency translation adjustments	-8,181	'	'	'	-8,181	'	'	'	'
Net unrealized holding gains (losses) arising during the period, net of other-than-temporary impairment losses and reclassification adjustment	26,682	'	'	'	'	26,682	'	'	'
Net change from current period hedging transactions, net of reclassification adjustment	'	'	'	'	'	'	67	'	'
Net income	263,877	'	'	'	'	'	'	'	263,877
Dividends on preferred shares	-24,564	'	'	'	'	'	'	'	-24,564
Dividends on common shares	'	'	'	'	'	'	'	'	-45,572
Balance, end of period at Sep. 30, 2014	$3,120,454	$17,200	$44,751	$590,330	$10,455	$72,632	($1,788)	$81,299	$2,386,874

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements Of Cash Flows (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	$263,877	$244,734
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Amortization of net premium on investments	34,128	39,933
Amortization of other intangibles and depreciation	20,593	15,131
Net realized and unrealized investment gains	-18,071	-9,967
Net impairment losses recognized in earnings	411	1,575
Deferred taxes	-5,058	1,935
Stock-based compensation expense	23,983	19,569
Equity in earnings of other investments	-22,542	-43,083
Premiums receivable, net	-783,030	-404,275
Insurance and reinsurance balances receivable	4,290	-18,114
Deferred acquisition costs	-60,410	-28,796
Prepaid reinsurance premiums	-226,804	-96,797
Reinsurance recoverable on unpaid losses	27,426	178,703
Reinsurance recoverable on paid losses	-1,372	-345,141
Accrued investment income	452	5,383
Other assets	-152	-6,875
Reserve for losses and loss expenses	-104,776	-188,774
Reserve for unearned premiums	533,317	349,443
Deposit liabilities	-1,937	-4,643
Reinsurance balances payable	301,032	236,205
Other liabilities	66,815	37,280
Net cash flows provided by (used in) operating activities	52,172	-16,574
Cash flows provided by (used in) investing activities	'	'
Proceeds from sales of available for sale investments	2,658,866	2,382,068
Proceeds from maturities and calls on available for sale investments	467,374	542,059
Proceeds from the redemption of other investments	34,072	28,485
Purchases of available for sale investments	-3,085,817	-3,094,718
Purchases of other investments	-52,731	-62,012
Net settlements of other assets	14,836	-38,223
Purchases of fixed assets	-34,038	-10,768
Net cash paid for subsidiary acquisition	-45	-378
Net cash flows provided by (used in) investing activities	2,517	-253,487
Cash flows used in financing activities	'	'
Issuance of common shares, net of forfeitures	1,480	31,289
Repurchase of common shares	0	-14,584
Settlement of equity awards	-4,039	-2,975
Loan facility costs paid	-4,750	0
Proceeds from issuance of debt	591	640
Repayments and repurchases of debt	-499	-624
Dividends on preferred shares	-24,564	-24,564
Dividends on common shares	-45,548	-42,174
Net cash flows used in financing activities	-77,329	-52,992
Effect of exchange rate changes on cash and cash equivalents	-17,495	-10,967
Net decrease in cash and cash equivalents	-40,135	-334,020
Cash and cash equivalents, beginning of period	845,851	1,124,019
Cash and cash equivalents, end of period	$805,716	$789,999

General

General	9 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
General	'
	1	General
	Endurance Specialty Holdings Ltd. (“Endurance Holdings” or the “Company”) was organized as a Bermuda holding company on June 27, 2002. Endurance Holdings writes specialty lines of insurance and reinsurance on a global basis through its wholly-owned operating subsidiaries:
	Operating Subsidiaries		Domicile
	Endurance Specialty Insurance Ltd.		Bermuda
	Endurance Worldwide Insurance Limited		England
	Endurance Reinsurance Corporation of America		Delaware
	Endurance American Insurance Company		Delaware
	Endurance American Specialty Insurance Company		Delaware
	Endurance Risk Solutions Assurance Co.		Delaware
	American Agri-Business Insurance Company		Texas

Summary_Of_Significant_Account

Summary Of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Summary Of Significant Accounting Policies	'
	2	Summary of significant accounting policies
	The accompanying unaudited condensed consolidated financial statements have been prepared on the basis of accounting principles generally accepted in the United States for interim financial information and with the instructions to the Quarterly Report on Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Results for the three and nine months ended September 30, 2014 are not necessarily indicative of the results that may be expected for the year ending December 31, 2014. The unaudited condensed consolidated financial statements include the accounts of Endurance Holdings and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Management is required to make estimates and assumptions that affect the amounts reported in the unaudited condensed consolidated financial statements and accompanying disclosures. Actual results could differ from those estimates. Among other matters, significant estimates and assumptions are used to record premiums written and ceded, to record the fair value of investments and to record reserves for losses and loss expenses and contingencies. Estimates and assumptions are periodically reviewed and the effects of revisions are recorded in the consolidated financial statements in the period that they are determined to be necessary.
	The balance sheet at December 31, 2013 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. These unaudited condensed consolidated financial statements and notes thereto should be read in conjunction with the consolidated financial statements and notes thereto for the year ended December 31, 2013 contained in Endurance Holdings’ Annual Report on Form 10-K for the fiscal year ended December 31, 2013 (the “2013 Form 10-K”).
	Certain comparative information has been reclassified to conform to current year presentation.
	There were no material changes in the Company’s significant accounting and reporting policies subsequent to the filing of the 2013 Form 10-K.
	In July 2013, the FASB issued ASU 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”). ASU 2013-11 provides guidance on the presentation of unrecognized tax benefits to better reflect the manner in which an entity would settle at the reporting date any additional income taxes that would result from the disallowance of a tax position when net operating loss carryforwards, similar tax losses, or tax credit carryforwards exist. ASU 2013-11 was effective for annual and interim reporting periods beginning after December 15, 2013, with both early adoption and retrospective application permitted. The Company adopted this standard effective January 1, 2014. This standard did not have a material impact on the Company’s consolidated financial statements.

Investments

Investments	9 Months Ended
	Sep. 30, 2014
Investments [Abstract]	'
Investments	'
	3	Investments
	Composition of Net Investment Income and of Invested Assets
	The components of net investment income for the three and nine months ended September 30, 2014 and 2013 are as follows:
		Three Months Ended September 30,							Nine Months Ended September 30,
		2014			2013				2014				2013
	Available for sale investments	$	29,959		$	27,889			$	91,905			$	86,036
	Other investments	(1,785		)	13,244				22,542				43,083
	Cash and cash equivalents	581			752				1,878				2,043
		$	28,755		$	41,885			$	116,325			$	131,162
	Investment expenses	(3,398		)	(3,788		)		(10,676		)		(11,292		)
	Net investment income	$	25,357		$	38,097			$	105,649			$	119,870
	The following table summarizes the composition of the investment portfolio by investment type at September 30, 2014 and December 31, 2013:
			30-Sep-14						31-Dec-13
	Type of Investment		Fair Value			Percentage			Fair Value				Percentage
	Fixed maturity investments		$	4,871,420		75.4	%		$	4,823,964			74.2	%
	Cash and cash equivalents (1)		652,377			10.1	%		771,714				11.9	%
	Other investments (2)		658,678			10.2	%		617,478				9.5	%
	Short-term investments		11,844			0.2	%		35,028				0.5	%
	Equity securities		267,728			4.1	%		252,466				3.9	%
	Total		$	6,462,047		100	%		$	6,500,650			100	%
	-1	Includes net receivable on sales of investments and net payable on purchases of investments.
	-2	Consists of investments in alternative funds and specialty funds.
	3	Investments, cont'd.
	The following table summarizes the composition by investment rating of the fixed maturity and short-term investments at September 30, 2014 and December 31, 2013. In some cases, where bonds are unrated, the rating of the issuer has been applied.
		30-Sep-14						31-Dec-13
	Ratings (1)	Fair Value			Percentage			Fair Value				Percentage
	U.S. government and agencies securities	$	514,672		10.5	%		$	769,343			15.8	%
	AAA / Aaa	1,153,558			23.7	%		972,820				20	%
	AA / Aa	1,738,964			35.7	%		1,771,156				36.5	%
	A / A	952,894			19.5	%		895,549				18.4	%
	BBB	407,093			8.3	%		363,722				7.5	%
	Below BBB	94,824			1.9	%		66,791				1.4	%
	Not rated	21,259			0.4	%		19,611				0.4	%
	Total	$	4,883,264		100	%		$	4,858,992			100	%
	-1	The credit rating for each security reflected above was determined based on the rating assigned to the individual security by Standard & Poor's Financial Services LLC ("Standard & Poor's"). If a rating is not supplied by Standard & Poor's, the equivalent rating supplied by Moody's Investors Service, Inc. ("Moody's"), Fitch Ratings, Inc., or DBRS, Inc. is used.
	Contractual maturities of the Company’s fixed maturity and short-term investments are shown below as of September 30, 2014 and December 31, 2013. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.
		30-Sep-14							31-Dec-13
		Amortized			Fair Value				Amortized				Fair Value
		Cost							Cost
	Due within one year	$	128,535		$	129,382			$	144,814			$	145,653
	Due after one year through five years	1,575,875			1,583,414				1,808,001				1,815,240
	Due after five years through ten years	339,764			341,993				290,391				288,486
	Due after ten years	33,034			35,474				26,344				26,937
	Residential mortgage-backed securities	1,185,911			1,203,322				1,192,085				1,187,191
	Commercial mortgage-backed securities	948,460			965,696				932,263				947,677
	Collateralized loan and debt obligations	205,465			207,214				92,519				94,552
	Asset-backed securities	414,968			416,769				351,192				353,256
	Total	$	4,832,012		$	4,883,264			$	4,837,609			$	4,858,992
	3	Investments, cont'd.
	In addition to the Company’s fixed maturity, short-term and equity investments, the Company invests in (i) hedge funds and private investment funds that generally invest in senior secured bank debt, high yield credit, distressed debt, distressed real estate, derivatives, and equity long/short strategies (“alternative funds”) and (ii) high yield loan and convertible debt funds (“specialty funds”). The Company’s alternative funds and specialty funds are recorded on the Company’s balance sheet as “other investments.” At September 30, 2014 and December 31, 2013, the Company had invested, net of capital returned, a total of $462.1 million and $440.9 million, respectively, in other investments. At September 30, 2014 and December 31, 2013, the carrying value of other investments was $658.7 million and $617.5 million, respectively. The following table summarizes the composition and redemption restrictions of other investments as of September 30, 2014 and December 31, 2013:
	30-Sep-14	Market Value			Unfunded				Ineligible for
					Commitments				Redemption over
									next 12 months
	Alternative funds
	Hedge funds	$	431,278		$	—			$	38,900
	Private investment funds	68,433			64,473				68,433
	Total alternative funds	499,711			64,473				107,333
	Specialty funds
	High yield loan funds	112,892			—				—
	Convertible debt funds	46,075			—				—
	Total specialty funds	158,967			—				—
	Total other investments	$	658,678		$	64,473			$	107,333
	31-Dec-13	Market Value			Unfunded				Ineligible for
Commitments					Redemption in 2014
Alternative funds
Hedge funds	$	401,438		$	—			$	47,406
Private investment funds	59,703			57,997				59,703
Total alternative funds	461,141			57,997				107,109
Specialty funds
High yield loan funds	111,254			—				—
Convertible debt funds	45,083			—				—
Total specialty funds	156,337			—				—
Total other investments	$	617,478		$	57,997			$	107,109
Hedge funds – The redemption frequency of the hedge funds range from monthly to biennially with notice periods from 30 to 90 days. Over one year, it is estimated that the Company can liquidate approximately 91.0% of the hedge fund portfolio, with the remainder over the following two years.
3	Investments, cont'd.
Private investment funds – The Company generally has no right to redeem its interest in any private investment funds in advance of dissolution of the applicable partnership. Instead, the nature of these investments is that distributions are received by the Company in connection with the liquidation of or distribution of earnings from the underlying assets of the applicable limited partnership. It is estimated that the majority of the underlying assets of the limited partnerships would liquidate over 5 to 10 years from inception of the limited partnership. A secondary market, with unpredictable liquidity, exists for limited partner interests in private equity funds.
High yield loan funds – There are generally no restrictions on the Company’s right to redeem its interest in high yield loan funds with the exception of certain redemption frequency and notice requirements. The redemption frequency of these funds ranges from monthly to quarterly with notice periods from 30 to 90 days.
Convertible debt funds – There are generally no restrictions on the Company’s right to redeem its interest in convertible debt funds with the exception of certain redemption frequency and notice requirements. The redemption frequency of these funds is monthly with a required notice period of 5 days.
Net Realized and Unrealized Investment Gains (Losses)
Realized and unrealized investment gains and losses are recognized in earnings using the first in, first out method. The analysis of net realized and unrealized investment gains (losses) and the change in the fair value of investment-related derivative financial instruments for the three and nine months ended September 30, 2014 and 2013 is as follows:
	Three Months Ended September 30,							Nine Months Ended September 30,
	2014			2013				2014				2013
Gross realized gains on investment sales	$	10,683		$	6,180			$	28,317			$	30,191
Gross realized losses on investment sales	(1,475		)	(13,178		)		(12,778		)		(19,924		)
Change in fair value of derivative financial instruments (1)	580			358				2,532				(300		)
Net realized and unrealized investment gains (losses)	$	9,788		$	(6,640	)		$	18,071			$	9,967
-1	For additional information on the Company’s derivative financial instruments, see Note 7.
3	Investments, cont'd.
Unrealized Gains and Losses and Other-Than-Temporary Impairments
The Company classifies its investments in fixed maturity investments, short-term investments and equities as available for sale. The amortized cost, fair value and related gross unrealized gains and losses and non-credit other-than-temporary impairment (“OTTI”) losses on the Company’s securities classified as available for sale at September 30, 2014 and December 31, 2013 are as follows:
	Amortized			Gross				Gross				Fair Value			Non-Credit
	Cost			Unrealized				Unrealized							OTTI (2)
				Gains				Losses
30-Sep-14
Fixed maturity investments
U.S. government and agencies securities	$	512,199		$	5,450			$	(2,977	)		$	514,672		$	—
U.S. state and municipal securities	31,437			207				(157		)		31,487			—
Foreign government securities	204,033			2,033				(373		)		205,693			—
Government guaranteed corporate securities	45,577			624				—				46,201			—
Corporate securities	1,272,119			13,037				(4,790		)		1,280,366			—
Residential mortgage-backed securities	1,185,911			21,984				(4,573		)		1,203,322			(3,319		)
Commercial mortgage-backed securities	948,460			20,763				(3,527		)		965,696			(5		)
Collateralized loan and debt obligations (1)	205,465			1,974				(225		)		207,214			—
Asset-backed securities	414,968			2,333				(532		)		416,769			—
Total fixed maturity investments	$	4,820,169		$	68,405			$	(17,154	)		$	4,871,420		$	(3,324	)
Short-term investments	11,843			1				—				11,844			—
Total fixed income investments	$	4,832,012		$	68,406			$	(17,154	)		$	4,883,264		$	(3,324	)
Equity securities
Equity investments	$	157,924		$	26,471			$	(1,881	)		$	182,514		$	—
Emerging market debt funds	60,250			1,612				—				61,862			—
Preferred equity investments	12,283			2,071				(37		)		14,317			—
Short-term fixed income fund	9,030			6				(1		)		9,035			—
Total equity securities	$	239,487		$	30,160			$	(1,919	)		$	267,728		$	—
-1	Balances include amounts related to collateralized debt obligations held with total fair values of $10.7 million.
-2	Represents total OTTI recognized in accumulated other comprehensive income. It does not include the change in fair value subsequent to the impairment measurement date. At September 30, 2014, the gross unrealized loss related to fixed income investments for which a non-credit OTTI was recognized in accumulated other comprehensive income was nil.
3	Investments, cont'd.
	Amortized			Gross				Gross				Fair Value			Non-Credit
	Cost			Unrealized				Unrealized							OTTI (2)
				Gains				Losses
31-Dec-13
Fixed maturity investments
U.S. government and agencies securities	$	771,227		$	5,735			$	(7,619	)		$	769,343		$	—
U.S. state and municipal securities	27,138			111				(395		)		26,854			—
Foreign government securities	183,650			1,003				(2,006		)		182,647			—
Government guaranteed corporate securities	34,921			274				(50		)		35,145			—
Corporate securities	1,217,585			16,225				(6,511		)		1,227,299			—
Residential mortgage-backed securities	1,192,085			17,005				(21,899		)		1,187,191			(4,257		)
Commercial mortgage-backed securities	932,263			23,423				(8,009		)		947,677			(47		)
Collateralized loan and debt obligations (1)	92,519			2,233				(200		)		94,552			—
Asset-backed securities	351,192			2,919				(855		)		353,256			(163		)
Total fixed maturity investments	$	4,802,580		$	68,928			$	(47,544	)		$	4,823,964		$	(4,467	)
Short-term investments	35,029			1				(2		)		35,028			—
Total fixed income investments	$	4,837,609		$	68,929			$	(47,546	)		$	4,858,992		$	(4,467	)
Equity securities
Equity investments	$	152,525		$	24,139			$	(1,995	)		$	174,669		$	—
Emerging market debt funds	60,250			594				—				60,844			—
Preferred equity investments	6,325			1,977				(79		)		8,223			—
Short-term fixed income funds	8,728			2				—				8,730			—
Total equity securities	$	227,828		$	26,712			$	(2,074	)		$	252,466		$	—
-1	Balances include amounts related to collateralized debt obligations held with total fair values of $18.7 million.
-2	Represents total OTTI recognized in accumulated other comprehensive income. It does not include the change in fair value subsequent to the impairment measurement date. At December 31, 2013, the gross unrealized loss related to fixed income investments for which a non-credit OTTI was recognized in accumulated other comprehensive income was $0.1 million.
3	Investments, cont'd.
The following tables summarize, for all available for sale securities in an unrealized loss position at September 30, 2014 and December 31, 2013, the aggregate fair value and gross unrealized loss by length of time the security has continuously been in an unrealized loss position.
	Less than 12 months							12 months or greater							Total
	Unrealized			Fair				Unrealized				Fair			Unrealized			Fair
	Losses			Value				Losses				Value			Losses			Value
30-Sep-14
Fixed maturity investments
U.S. government and agencies securities	$	(559	)	$	95,967			$	(2,418	)		$	95,856		$	(2,977	)	$	191,823
U.S. state and municipal securities	(78		)	7,261				(79		)		6,835			(157		)	14,096
Foreign government securities	(204		)	43,104				(169		)		23,314			(373		)	66,418
Corporate securities	(3,026		)	432,053				(1,764		)		97,104			(4,790		)	529,157
Residential mortgage-backed securities	(593		)	168,976				(3,980		)		152,520			(4,573		)	321,496
Commercial mortgage-backed securities	(1,186		)	200,660				(2,341		)		93,769			(3,527		)	294,429
Collateralized loan and debt obligations	(174		)	95,995				(51		)		1,467			(225		)	97,462
Asset-backed securities	(264		)	156,553				(268		)		29,991			(532		)	186,544
Total fixed income investments	$	(6,084	)	$	1,200,569			$	(11,070	)		$	500,856		$	(17,154	)	$	1,701,425
Equity securities
Equity investments	$	(1,861	)	$	40,720			$	(20	)		$	141		$	(1,881	)	$	40,861
Preferred equity investments	(37		)	5,676				—				—			(37		)	5,676
Short-term fixed income fund	(1		)	2,899				—				—			(1		)	2,899
Total equity securities	$	(1,899	)	$	49,295			$	(20	)		$	141		$	(1,919	)	$	49,436
As of September 30, 2014, 752 available for sale securities were in an unrealized loss position aggregating $19.1 million. Of those, 222 securities with aggregated unrealized losses of $11.1 million had been in a continuous unrealized loss position for twelve months or greater.
3	Investments, cont'd.
	Less than 12 months							12 months or greater							Total
	Unrealized			Fair				Unrealized				Fair			Unrealized			Fair
	Losses (1)			Value				Losses (1)				Value			Losses (1)			Value
31-Dec-13
Fixed maturity investments
U.S. government and agencies securities	$	(7,359	)	$	382,593			$	(260	)		$	6,050		$	(7,619	)	$	388,643
U.S. state and municipal securities	(395		)	20,452				—				—			(395		)	20,452
Foreign government securities	(1,981		)	139,503				(25		)		5,261			(2,006		)	144,764
Government guaranteed corporate securities	(50		)	13,326				—				—			(50		)	13,326
Corporate securities	(5,959		)	478,287				(552		)		28,690			(6,511		)	506,977
Residential mortgage-backed securities	(17,542		)	514,702				(4,357		)		102,446			(21,899		)	617,148
Commercial mortgage-backed securities	(7,681		)	384,548				(328		)		16,804			(8,009		)	401,352
Collateralized loan and debt obligations	(48		)	20,733				(152		)		2,379			(200		)	23,112
Asset-backed securities	(703		)	157,172				(152		)		7,011			(855		)	164,183
Total fixed maturity investments	$	(41,718	)	$	2,111,316			$	(5,826	)		$	168,641		$	(47,544	)	$	2,279,957
Short-term investments	(2		)	2,468				—				—			(2		)	2,468
Total fixed income investments	$	(41,720	)	$	2,113,784			$	(5,826	)		$	168,641		$	(47,546	)	$	2,282,425
Equity securities
Equity investments	$	(1,995	)	$	36,751			$	—			$	—		$	(1,995	)	$	36,751
Preferred equity investments	(79		)	2,987				—				—			(79		)	2,987
Total equity securities	$	(2,074	)	$	39,738			$	—			$	—		$	(2,074	)	$	39,738
-1	Gross unrealized losses include unrealized losses on non-OTTI and non-credit OTTI securities recognized in accumulated other comprehensive income at December 31, 2013.
As of December 31, 2013, 880 available for sale securities were in an unrealized loss position aggregating $49.6 million. Of those, 71 securities with aggregated unrealized losses of $5.8 million had been in a continuous unrealized loss position for twelve months or greater.
The analysis of OTTI for the three and nine months ended September 30, 2014 and 2013 is as follows:
	Three Months Ended September 30,							Nine Months Ended September 30,
	2014			2013				2014				2013
Total other-than-temporary impairment losses	$	(102	)	$	(190	)		$	(411	)		$	(1,575	)
Portion of loss recognized in other comprehensive (loss) income	—			—				—				—
Net impairment losses recognized in earnings	$	(102	)	$	(190	)		$	(411	)		$	(1,575	)
3	Investments, cont'd.
Of the $0.1 million (2013: $0.2 million) of OTTI losses recognized by the Company in the third quarter of 2014, the majority was related to equity investments that had been at a loss for over a year. The decrease in gross unrealized losses on the Company’s fixed income investments at September 30, 2014 compared to December 31, 2013 was primarily due to a decrease in longer term interest rates during the period. At September 30, 2014, the Company did not have the intent to sell any of the remaining fixed income investments in an unrealized loss position and determined that it was unlikely that the Company would be required to sell those securities in an unrealized loss position. The Company has the ability and intent to hold its equity securities until recovery; therefore, the Company does not consider its fixed income investments or equity securities to be other-than-temporarily impaired at September 30, 2014.
The following table provides a roll-forward of the amount related to credit losses for the Company’s available for sale investments recognized in earnings for which a portion of an OTTI loss was recognized in accumulated other comprehensive income for the three and nine months ended September 30, 2014 and 2013:
	Three Months Ended September 30,							Nine Months Ended September 30,
	2014			2013				2014				2013
Beginning balance	$	(1,441	)	$	(1,769	)		$	(1,553	)		$	(2,000	)
Addition for the amount related to the credit loss for which an other-than-temporary impairment was not previously recognized	—			—				—				—
Addition for the amount related to the credit loss for which an other-than-temporary impairment was previously recognized	—			—				—				—
Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security	—			—				—				—
Reductions for securities sold during the period	579			113				691				344
Ending balance	$	(862	)	$	(1,656	)		$	(862	)		$	(1,656	)
Variable Interest Entities
Entities that do not have sufficient equity at risk to allow the entity to finance its activities without additional financial support or in which the equity investors, as a group, do not have the characteristics of a controlling financial interest are referred to as variable interest entities (“VIE”). A VIE is consolidated by the variable interest holder that is determined to have the controlling financial interest (primary beneficiary) as a result of having both the power to direct the activities of a VIE that most significantly impact the VIE’s economic performance and the obligation to absorb losses or right to receive benefits from the VIE that could potentially be significant to the VIE. The Company determines whether it is the primary beneficiary of an entity subject to consolidation based on a qualitative assessment of the VIE’s capital structure, contractual terms, nature of the VIE’s operations and purpose and the Company’s relative exposure to the related risks of the VIE on the date it becomes initially involved in the VIE. The Company reassesses its VIE determination with respect to an entity on an ongoing basis.
The Company is involved in the normal course of business with VIEs primarily as a passive investor in residential and commercial mortgage-backed securities and through its interests in various other investments that are structured as limited partnerships considered to be third party VIEs. The Company determined that it was not the primary beneficiary for any of these investments as of September 30, 2014. The Company believes its exposure to loss with respect to these investments is generally limited to the investment carrying amounts reported in the Company’s Condensed Consolidated Balance Sheets and any unfunded investment commitments.

Fair_Value_Measurement

Fair Value Measurement	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurement	'
	4	Fair value measurement
	The Company determines the fair value of the fixed maturity investments, short-term investments, equity securities, other investments, debt, and other assets and liabilities in accordance with current accounting guidance, which defines fair value and establishes a fair value hierarchy based on inputs to the various valuation techniques used for each fair value measurement. The Company determines the estimated fair value of each individual security utilizing the highest level inputs available. Valuation inputs by security type may include the following:
	•	Government and agencies fixed maturity securities – These securities are generally priced by pricing services or index providers. The pricing services or index providers may use current market trades for securities with similar quality, maturity and coupon. If no such trades are available, the pricing service typically uses analytical models which may incorporate option adjusted spreads, daily interest rate data and market/sector news. The Company generally classifies the fair values of government and agencies securities in Level 2. Current issue U.S. government securities are generally valued based on Level 1 inputs, which use the market approach valuation technique.
	•	Government guaranteed corporate fixed maturity securities – These securities are generally priced by pricing services or index providers. The pricing service or index providers may use current market trades for securities with similar quality, maturity and coupon. If no such trades are available, the pricing service typically uses analytical spread models which may incorporate inputs from the U.S treasury curve or LIBOR. The Company generally classifies the fair values of its government guaranteed corporate securities in Level 2.
	•	Corporate fixed maturity securities – These securities are generally priced by pricing services or index providers. The pricing services or index providers typically use discounted cash flow models that incorporate benchmark curves for treasury, swap and high issuance credits. Credit spreads are developed from current market observations for like or similar securities. The Company generally classifies the fair values of its corporate securities in Level 2.
	•	Equity securities – These securities are generally priced by pricing services or index providers. Depending on the type of underlying equity security or equity fund, the securities are priced by pricing services or index providers based on quoted market prices in active markets or through a discounted cash flow model that incorporates benchmark curves for treasury, swap and credits for like or similar securities. The Company generally classifies the fair values of its equity securities in Level 1 or 2.
	•	Other assets and liabilities – A portion of other assets and liabilities are composed of a variety of derivative instruments used to enhance the efficiency of the investment portfolio and economically hedge certain risks. These instruments are generally priced by pricing services, broker/dealers and/or recent trading activity. The market value approach valuation technique is used to estimate the fair value for these derivatives based on significant observable market inputs. Certain derivative instruments are priced by pricing services based on quoted market prices in active markets. These derivative instruments are generally classified in Level 1. Other derivative instruments are priced using industry valuation models and are considered Level 2, as the inputs to the valuation model are based on observable market inputs. Also included in this line item are proprietary, non-exchange traded derivative-based risk management products primarily used to address weather and energy risks. The trading market for these weather derivatives are generally linked to energy and agriculture commodities, weather and other natural phenomena. In instances where market prices are not available, the Company uses industry or internally developed valuation techniques such as spread option, Black Scholes, quanto and simulation modeling to determine fair value and classifies these in Level 3. These models may reference prices for similar instruments.
	•	Structured securities including agency and non-agency, residential and commercial, mortgage and asset-backed securities and collateralized loan and debt obligations – These securities are generally priced by broker/dealers. Broker/dealers may use current market trades for securities with similar qualities. If no such trades are available, inputs such as bid and offer, prepayment speeds, the U.S. treasury curve, swap curve and cash settlement may be used in a discounted cash flow model to determine the fair value of a security. The Company generally classifies the fair values of its structured securities in Level 2.
	4	Fair value measurement, cont'd.
	•	Other investments – Other investments are comprised of alternative funds and specialty funds and are generally priced on net asset values (“NAV”) received from the fund managers or administrators. Due to the timing of the delivery of the final NAV by certain of the fund managers, valuations of certain alternative funds and specialty funds are estimated based on the most recently available information, including period end NAVs, period end estimates, or, in some cases, prior month or prior quarter NAVs. As this valuation technique incorporates both observable and significant unobservable inputs, the Company generally classifies the fair value of its other investments in Level 3.
	•	Debt – Outstanding debt consists of the Company’s 6.15% Senior Notes due October 15, 2015 and the 7.0% Senior Notes due July 15, 2034 (the “Senior Notes”). The fair values of these securities were obtained from a third party pricing service and pricing was based on the spread above the risk-free yield curve. These spreads are generally obtained from the new issue market, secondary trading and broker-dealer quotes. As these spreads and the yields for the risk-free yield curve are observable market inputs, the fair values of the Senior Notes are classified in Level 2.
	The carrying values of cash and cash equivalents, accrued investment income, net receivable on sales of investments, net payable on purchases of investments and other financial instruments not described above approximated their fair values at September 30, 2014.
	Transfers between levels are assumed to occur at the end of each period.
	4	Fair value measurement, cont'd.
	The following table sets forth the Company’s available for sale investments, other investments, other assets and liabilities and debt categorized by the level within the hierarchy in which the fair value measurements fall at September 30, 2014:
		Fair Value Measurements at September 30, 2014
		Total at			Quoted			Significant			Significant
		September 30, 2014			Prices in			Other			Unobservable
					Active			Observable			Inputs
					Markets for			Inputs			(Level 3)
					Identical			(Level 2)
					Assets
					(Level 1)
	Assets
	Fixed maturity investments
	U.S. government and agencies securities	$	514,672		$	—		$	514,672		$	—
	U.S. state and municipal securities	31,487			—			31,487			—
	Foreign government securities	205,693			—			205,693			—
	Government guaranteed corporate securities	46,201			—			46,201			—
	Corporate securities	1,280,366			—			1,279,666			700
	Residential mortgage-backed securities	1,203,322			—			1,203,294			28
	Commercial mortgage-backed securities	965,696			—			962,868			2,828
	Collateralized loan and debt obligations	207,214			—			206,574			640
	Asset-backed securities	416,769			—			413,772			2,997
	Total fixed maturity investments	$	4,871,420		$	—		$	4,864,227		$	7,193
	Equity securities
	Equity investments	182,514			123,283			59,231			—
	Emerging market debt funds	61,862			—			61,862			—
	Preferred equity investments	14,317			—			14,317			—
	Short-term fixed income fund	9,035			9,035			—			—
	Total equity securities	$	267,728		$	132,318		$	135,410		$	—
	Short-term investments	11,844			—			11,844			—
	Other investments	658,678			—			—			658,678
	Other assets (see Note 7)	147,488			—			132,666			14,822
	Total assets	$	5,957,158		$	132,318		$	5,144,147		$	680,693
	Liabilities
	Other liabilities (see Note 7)	$	95,704		$	—		$	79,788		$	15,916
	Debt	615,568			—			615,568			—
	Total liabilities	$	711,272		$	—		$	695,356		$	15,916
	During the three months ended September 30, 2014, $2.2 million of commercial mortgage-backed securities were transferred into Level 3 as no observable inputs were available, and $5.0 million of primarily residential mortgage-backed securities and collateralized loan and debt obligations were transferred out of Level 3 to Level 2 during the period as market activity for these securities increased and observable inputs became available.
	During the nine months ended September 30, 2014, $7.2 million of primarily commercial and residential mortgage-backed securities were transferred into Level 3 as no observable inputs were available, and $6.8 million of primarily commercial and residential mortgage-backed securities and collateralized loan and debt obligations were transferred out of Level 3 as market activity for these securities increased and observable inputs became available. During the three and nine months ended September 30, 2014, $6.6 million of U.S. government and agencies securities were transferred from Level 1 to Level 2 as they no longer qualified as on the run U.S. treasury securities.
	4	Fair value measurement, cont'd.
	The following table sets forth the Company’s available for sale investments, other investments, other assets and liabilities and debt categorized by the level within the hierarchy in which the fair value measurements fall at December 31, 2013:
		Fair Value Measurements at December 31, 2013
		Total at			Quoted			Significant			Significant
		December 31, 2013			Prices in			Other			Unobservable
					Active			Observable			Inputs
					Markets for			Inputs			(Level 3)
					Identical			(Level 2)
					Assets
					(Level 1)
	Assets
	Fixed maturity investments
U.S. government and agencies securities	$	769,343		$	20,248		$	749,095		$	—
U.S. state and municipal securities	26,854			—			26,854			—
Foreign government securities	182,647			—			182,647			—
Government guaranteed corporate securities	35,145			—			35,145			—
Corporate securities	1,227,299			—			1,226,553			746
Residential mortgage-backed securities	1,187,191			—			1,186,943			248
Commercial mortgage-backed securities	947,677			—			946,794			883
Collateralized loan and debt obligations	94,552			—			92,095			2,457
Asset-backed securities	353,256			—			350,262			2,994
Total fixed maturity investments	$	4,823,964		$	20,248		$	4,796,388		$	7,328
Equity securities
Equity investments	174,669			117,776			56,893			—
Emerging market debt funds	60,844			—			60,844			—
Preferred equity investments	8,223			—			8,223			—
Short-term fixed income fund	8,730			8,730			—			—
Total equity securities	$	252,466		$	126,506		$	125,960		$	—
Short-term investments	35,028			—			35,028			—
Other investments	617,478			—			—			617,478
Other assets (see Note 7)	108,272			—			94,234			14,038
Total assets	$	5,837,208		$	146,754		$	5,051,610		$	638,844
Liabilities
Other liabilities (see Note 7)	$	49,452		$	—		$	29,883		$	19,569
Debt	575,115			—			575,115			—
Total liabilities	$	624,567		$	—		$	604,998		$	19,569
Level 3 assets represented 11.4% and 10.9% of the Company’s total available for sale investments, other investments and derivative instruments at September 30, 2014 and December 31, 2013, respectively. Level 3 securities are primarily comprised of non-agency commercial mortgage-backed securities, asset-backed securities, investments in alternative and specialty funds, and weather derivatives. The NAV used to measure the fair value of the Company’s other investments are generally derived from the underlying investments held within the funds. Although the Company does not have direct access to detailed financial information related to the underlying investments of the funds, the Company obtains and reviews fund financial statements, internal control review reports, and industry benchmarking reports to determine the reasonability of the NAV of the funds. There were no material changes in the Company’s valuation techniques for the nine months ended September 30, 2014.
4	Fair value measurement, cont'd.
Other assets and other liabilities measured at fair value at September 30, 2014 include assets of $14.8 million (2013 - $14.0 million) and liabilities of $15.9 million (2013 - $19.6 million) related to proprietary, non-exchange traded derivative-based risk management products used in the Company’s weather risk management business, and hedging and trading activities related to these risks. In instances where market prices are not available, the Company may use industry or internally developed valuation techniques such as historical analysis and simulation modeling to determine fair value and are considered Level 3.
Observable and unobservable inputs to these valuation techniques vary by contract requirements and commodity type, are validated using market-based or independently sourced parameters where applicable and may include the following:
•Observable inputs: contract price, notional, option strike, term to expiry, interest rate, contractual limits;
•Unobservable inputs: correlation; and
•Both observable and unobservable: forward commodity price, forward weather curve.
The Company’s weather curves are determined by taking the average payouts for each transaction within its portfolio utilizing detrended historical weather measurements. The Company’s commodity curves are determined using historical market data scaled to currently observed market prices. The range of each unobservable input could vary based on the specific commodity, including, but not limited to natural gas, electricity, crude, liquids, temperature or precipitation. Due to the diversity of the portfolio, the range of unobservable inputs could be wide-spread as reflected in the below table on quantitative information.
If a trade has one or more significant valuation inputs that are unobservable, such trades are initially valued at the transaction price, which is considered to be the best initial estimate of fair value. Subsequent to the initial valuation, the Company updates market observable inputs to reflect observable market changes. The unobservable inputs are validated at each reporting period and are only changed when corroborated by evidence such as similar market transactions, third-party pricing services and/or broker or dealer quotations or other empirical market data.
Changes in any or all of the unobservable inputs listed above may contribute positively or negatively to the overall portfolio fair value depending upon the underlying position. In general, movements in weather curves are the largest contributing factor that impacts fair value.
Below is a summary of quantitative information regarding the significant unobservable inputs used in determining the fair value of the net weather and energy related derivative liabilities classified in Level 3 that are measured at fair value on a recurring basis at September 30, 2014:
	30-Sep-14
	Fair Value			Valuation		Unobservable	Low			High			Weighted Average
	(Level 3)			Techniques		Inputs							or Actual
	(U.S. dollars in thousands, except for correlation and commodity curve)
Net weather and energy related derivative liabilities	$	(1,094	)	Historical		Correlation	0			1			Actual
				Analysis and Simulation
						Weather curve	$	400		$	2,500		Actual
						Commodity curve	$	28.5		$	122.2		Actual
There were no impairment losses on Level 3 securities recognized in earnings for the three and nine months ended September 30, 2014 or 2013.
4	Fair value measurement, cont'd.
The following tables present a reconciliation of the beginning and ending balances for all assets and liabilities measured at fair value on a recurring basis using Level 3 inputs during the three months ended September 30, 2014 and 2013:
	Three Months Ended September 30, 2014
	Fixed maturity			Other			Other assets			Total assets			Other
	investments			investments									liabilities
Level 3, beginning of period	$	9,515		$	648,642		$	10,992		$	669,149		$	(10,284	)
Total equity income and realized gains included in earnings	9			10,913			—			10,922			—
Total equity losses and losses included in earnings	(6		)	(12,698		)	—			(12,704		)	—
Total income included in other underwriting income (loss)	—			—			3,180			3,180			4,794
Total loss included in other underwriting income (loss)	—			—			(5,235		)	(5,235		)	(3,719		)
Change in unrealized gains included in other comprehensive (loss) income	245			—			—			245			—
Change in unrealized losses included in other comprehensive (loss) income	(104		)	—			—			(104		)	—
Purchases	842			26,190			1,501			28,533			(751		)
Issues	—			—			7,331			7,331			(10,917		)
Sales	(545		)	(14,369		)	—			(14,914		)	—
Settlements	—			—			(2,947		)	(2,947		)	4,961
Transfers into Level 3	2,198			—			—			2,198			—
Transfers out of Level 3	(4,961		)	—			—			(4,961		)	—
Level 3, end of period	$	7,193		$	658,678		$	14,822		$	680,693		$	(15,916	)
	Three Months Ended September 30, 2013
	Fixed maturity			Other			Other assets			Total assets			Other
	investments			investments									liabilities
Level 3, beginning of period	$	7,546		$	569,393		$	—		$	576,939		$	—
Total equity income and realized gains included in earnings	56			19,108			—			19,164			—
Total equity losses and losses included in earnings	(15		)	(5,864		)	—			(5,879		)	—
Total income included in other underwriting income (loss)	—			—			—			—			—
Total loss included in other underwriting income (loss)	—			—			—			—			—
Change in unrealized gains included in other comprehensive (loss) income	111			—			—			111			—
Change in unrealized losses included in other comprehensive (loss) income	(62		)	—			—			(62		)	—
Purchases	—			16,597			—			16,597			—
Sales	(1,879		)	(5,078		)	—			(6,957		)	—
Transfers in to Level 3	7,903			—			—			7,903			—
Transfers out of Level 3	(1,202		)	—			—			(1,202		)	—
Level 3, end of period	$	12,458		$	594,156		$	—		$	606,614		$	—
4	Fair value measurement, cont'd.
The following tables present a reconciliation of the beginning and ending balances for all assets and liabilities measured at fair value on a recurring basis using Level 3 inputs during the nine months ended September 30, 2014 and 2013:
	Nine Months Ended September 30, 2014
	Fixed maturity			Other			Other assets			Total assets			Other
	investments			investments									liabilities
Level 3, beginning of period	$	7,328		$	617,478		$	14,038		$	638,844		$	(19,569	)
Total equity income and realized gains included in earnings	62			46,385			—			46,447			—
Total equity losses and losses included in earnings	(32		)	(23,844		)	—			(23,876		)	—
Total income included in other underwriting income (loss)	—			—			18,396			18,396			24,842
Total loss included in other underwriting income (loss)	—			—			(23,845		)	(23,845		)	(20,672		)
Change in unrealized gains included in other comprehensive (loss) income	445			—			—			445			—
Change in unrealized losses included in other comprehensive (loss) income	(255		)	—			—			(255		)	—
Purchases	842			52,731			1,501			55,074			(751		)
Issues	—			—			10,912			10,912			(18,080		)
Sales	(1,585		)	(34,072		)	—			(35,657		)	—
Settlements	—			—			(6,180		)	(6,180		)	18,314
Transfers in to Level 3	7,201			—			—			7,201			—
Transfers out of Level 3	(6,813		)	—			—			(6,813		)	—
Level 3, end of period	$	7,193		$	658,678		$	14,822		$	680,693		$	(15,916	)
	Nine Months Ended September 30, 2013
	Fixed maturity			Other			Other assets			Total assets			Other
	investments			investments									liabilities
Level 3, beginning of period	$	8,497		$	517,546		$	882		$	526,925		$	(1,922	)
Total equity income and realized gains included in earnings	104			61,010			—			61,114			—
Total equity losses and losses included in earnings	(17		)	(17,927		)	—			(17,944		)	—
Total income included in other underwriting income (loss)	—			—			—			—			2,354
Total loss included in other underwriting income (loss)	—			—			(1,182		)	(1,182		)	—
Change in unrealized gains included in other comprehensive income (loss)	438			—			—			438			—
Change in unrealized losses included in other comprehensive income (loss)	(270		)	—			—			(270		)	—
Purchases	—			62,011			—			62,011			—
Issues	—			—			300			300			(432		)
Sales	(6,081		)	(28,484		)	—			(34,565		)	—
Transfers in to Level 3	11,550			—			—			11,550			—
Transfers out of Level 3	(1,763		)	—			—			(1,763		)	—
Level 3, end of period	$	12,458		$	594,156		$	—		$	606,614		$	—

Earnings_Per_Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	5.     Earnings per share
	The two-class method utilized by the Company is an earnings allocation formula that determines earnings per share for the holders of Endurance Holdings’ ordinary shares (also referred to as “common shares”) and participating common shares, which includes unvested restricted shares that receive cash dividends, according to dividends declared and participation rights in undistributed earnings. Net income available to common and participating common shareholders is reduced by the amount of dividends declared in the current period and by the contractual amount of dividends that must be paid for the current period related to the Company’s common and participating common shares. Any remaining undistributed earnings are allocated to the common and participating common shareholders to the extent that each security may share in earnings as if all of the earnings for the period had been distributed. In periods of loss, no losses are allocated to participating common shareholders. Instead, all such losses are allocated solely to the common shareholders.
	Basic earnings per common share are calculated by dividing net income available to common shareholders by the weighted average number of common shares outstanding. The weighted average number of common shares excludes any dilutive effect of outstanding options and convertible securities such as unvested restricted shares.
	Diluted earnings per common share are based on the weighted average number of common shares and assumes the exercise of all dilutive stock options and the vesting or conversion of all convertible securities such as unvested restricted shares using the two-class method described above.
	The following table sets forth the computation of basic and diluted earnings per share for the three and nine months ended September 30, 2014 and 2013:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Numerator:
	Net income available to common and participating common shareholders	$	68,046		$	75,228		$	239,313		$	220,170
	Less amount allocated to participating common	(1,930		)	(1,997		)	(6,907		)	(4,742		)
	shareholders(1)
	Net income allocated to common shareholders	$	66,116		$	73,231		$	232,406		$	215,428
	Denominator:
	Weighted average shares - basic	43,464,790			43,099,841			43,332,461			42,719,837
	Share equivalents:
	Options	45,625			—			23,237			—
	Restricted share units	—			298			94			594
	Weighted average shares - diluted	43,510,415			43,100,139			43,355,792			42,720,431
	Basic earnings per common share	$	1.52		$	1.7		$	5.36		$	5.04
	Diluted earnings per common share	$	1.52		$	1.7		$	5.36		$	5.04
	-1	Represents earnings attributable to holders of unvested restricted shares issued under the Company's equity compensation plan that are considered participating. In periods of loss, no losses are allocated to participating common shareholders (unvested restricted shares).
	5.     Earnings per share, cont'd.
	Endurance Holdings declared a dividend of $0.484375 per Series A preferred share and $0.468750 per Series B preferred share on August 15, 2014 (2013 - Series A: $0.484375, Series B: $0.468750). The Series A and Series B preferred share dividends were paid on September 15, 2014 to shareholders of record on August 29, 2014. Endurance Holdings also declared a dividend of $0.34 per common share on August 15, 2014 (2013 - $0.32). The dividend was paid on September 30, 2014 to shareholders of record on September 15, 2014.
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Dividends declared per Series A preferred share	$	0.484375		$	0.484375		$	1.453125		$	1.453125
	Dividends declared per Series B preferred share	$	0.46875		$	0.46875		$	1.40625		$	1.40625
	Dividends declared per common share	$	0.34		$	0.32		$	1.02		$	0.96

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'
Accumulated Other Comprehensive Income	'
	6	Accumulated other comprehensive income
	The following tables present the changes in accumulated other comprehensive income balances by component for the three months ended September 30, 2014 and 2013:
		For the Three Months Ended September 30, 2014
		Losses on				Unrealized gains (losses) on available for sale securities			Foreign currency translation adjustments			Total
		cash flow hedges
	Beginning balance	$	(1,810	)		$	106,989		$	30,859		$	136,038
	Other comprehensive (loss) income before reclassifications	—				(25,100		)	(20,404		)	(45,504		)
	Amounts reclassified from accumulated other comprehensive income (1)	22				(9,257		)	—			(9,235		)
	Net current period other comprehensive (loss) income	22				(34,357		)	(20,404		)	(54,739		)
	Ending balance	$	(1,788	)		$	72,632		$	10,455		$	81,299
	(1)All amounts are net of tax.
		For the Three Months Ended September 30, 2013
		Losses on cash flow hedges				Unrealized gains on available for sale securities			Foreign currency translation adjustments			Total
	Beginning balance	$	(1,899	)		30,636			$	2,701		$	31,438
	Other comprehensive (loss) income before reclassifications	—				22,358			8,918			31,276
	Amounts reclassified from accumulated other comprehensive income (1)	22				6,721			—			6,743
	Net current period other comprehensive (loss) income	22				29,079			8,918			38,019
	Ending balance	$	(1,877	)		$	59,715		$	11,619		$	69,457
	(1)All amounts are net of tax.
	6	Accumulated other comprehensive income, cont'd.
	The following tables present the changes in accumulated other comprehensive income balances by component for the nine months ended September 30, 2014 and 2013:
		For the Nine Months Ended September 30, 2014
		Losses on cash flow hedges				Unrealized gains (losses) on available for sale securities			Foreign currency translation adjustments			Total
	Beginning balance	$	(1,855	)		$	45,950		$	18,636		$	62,731
	Other comprehensive (loss) income before reclassifications	—				41,895			(8,181		)	33,714
	Amounts reclassified from accumulated other comprehensive income (1)	67				(15,213		)	—			(15,146		)
	Net current period other comprehensive (loss) income	67				26,682			(8,181		)	18,568
	Ending balance	$	(1,788	)		$	72,632		$	10,455		$	81,299
	(1)All amounts are net of tax.
		For the Nine Months Ended September 30, 2013
		Losses on cash flow hedges				Unrealized gains (losses) on available for sale securities			Foreign currency translation adjustments			Total
	Beginning balance	$	(1,944	)		$	141,731		$	12,676		$	152,463
	Other comprehensive (loss) income before reclassifications	—				(74,001		)	(1,057		)	(75,058		)
	Amounts reclassified from accumulated other comprehensive income (1)	67				(8,015		)	—			(7,948		)
	Net current period other comprehensive (loss) income	67				(82,016		)	(1,057		)	(83,006		)
	Ending balance	$	(1,877	)		$	59,715		$	11,619		$	69,457
	(1)All amounts are net of tax.
	6	Accumulated other comprehensive income, cont'd.
	The following tables present the significant items reclassified out of accumulated other comprehensive income during the three months ended September 30, 2014 and 2013:
	Three Months Ended September 30, 2014
	Details about accumulated other comprehensive		Amount reclassified				Affected line item in the Unaudited
	income components		from accumulated other				Condensed Consolidated Statements of
			comprehensive income				Income and Comprehensive Income
	Losses on cash flow hedges - Debt		$	22			Interest expense
			22				Total before income taxes
			—				Income tax expense
			$	22			Total net of income taxes
	Unrealized (gains) losses on available for sale securities		$	(9,208	)		Net realized and unrealized investment gains
			102				Net impairment losses recognized in earnings
			(9,106		)		Total before income taxes
			195				Income tax expense
			$	(8,911	)		Total net of income taxes
	Three Months Ended September 30, 2013
	Details about accumulated other comprehensive		Amount reclassified				Affected line item in the Unaudited
	income components		from accumulated other				Condensed Consolidated Statements of
			comprehensive income				Income and Comprehensive Income
	Losses on cash flow hedges - Debt		$	22			Interest expense
			22				Total before income taxes
			—				Income tax expense
			$	22			Total net of income taxes
	Unrealized losses on available for sale securities		$	6,999			Net realized and unrealized investment losses
			190				Net impairment losses recognized in earnings
			7,189				Total before income taxes
		(468		)		Income tax benefit
		$	6,721			Total net of income taxes
6	Accumulated other comprehensive income, cont'd.
The following tables present the significant items reclassified out of accumulated other comprehensive income during the nine months ended September 30, 2014 and 2013:
Nine Months Ended September 30, 2014
Details about accumulated other comprehensive		Amount reclassified				Affected line item in the Unaudited
income components		from accumulated other				Condensed Consolidated Statements of
		comprehensive income				Income and Comprehensive Income
Losses on cash flow hedges - Debt		$	67			Interest expense
		67				Total before income taxes
		—				Income tax expense
		$	67			Total net of income taxes
Unrealized (gains) losses on available for sale securities		$	(15,539	)		Net realized and unrealized investment gains
		411				Net impairment losses recognized in earnings
		(15,128		)		Total before income taxes
		(85		)		Income tax benefit
		$	(15,213	)		Total net of income taxes
Nine Months Ended September 30, 2013
Details about accumulated other comprehensive		Amount reclassified				Affected line item in the Unaudited
income components		from accumulated other				Condensed Consolidated Statements of
		comprehensive income				Income and Comprehensive Income
Losses on cash flow hedges - Debt		$	67			Interest expense
		67				Total before income taxes
		—				Income tax expense
		$	67			Total net of income taxes
Unrealized (gains) losses on available for sale securities		$	(10,267	)		Net realized and unrealized investment gains
		1,575				Net impairment losses recognized in earnings
		(8,692		)		Total before income taxes
		677				Income tax expense
		$	(8,015	)		Total net of income taxes

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivatives	'
	7	Derivatives
	The Company regularly transacts in certain derivative-based weather risk management products primarily to address weather and energy risks on behalf of third parties. The markets for these derivatives are generally linked to energy and agriculture commodities, weather and other natural phenomena. Generally, the Company’s current portfolio of such derivative contracts is of short duration and such contracts are predominantly seasonal in nature. The Company also invests a portion of its fixed maturity assets with third party investment managers with investment guidelines that permit the use of derivative instruments. The Company may enter derivative transactions directly or as part of strategies employed by its external investment managers.
	The Company’s derivative instruments are recorded in the Condensed Consolidated Balance Sheets at fair value, with changes in fair value and gains and losses recognized in net realized and unrealized investment gains (losses), net foreign exchange losses and other underwriting income (loss) in the Condensed Consolidated Statements of Income and Comprehensive Income.
	The Company’s derivatives are not designated as hedges under current accounting guidance.
	The Company’s objectives for holding these derivatives are as follows:
	Interest Rate Futures, Swaps, Swaptions and Options - to manage exposure to interest rate risk, which can include increasing or decreasing its exposure to this risk through modification of the portfolio composition and duration.
	Foreign Exchange Forwards, Futures and Options - as part of overall currency risk management and investment strategies.
	Credit Default Swaps - to manage market exposures. The Company may assume or economically hedge credit risk through credit default swaps to replicate or hedge investment positions. The original term of these credit default swaps is generally five years or less.
	To-Be-Announced Mortgage-backed Securities (“TBAs”) - to enhance investment performance and as part of overall investment strategy. TBAs represent commitments to purchase or sell a future issuance of agency mortgage-backed securities. For the period between purchase of a TBA and issuance of the underlying securities, the Company’s position is accounted for as a derivative.
	Energy and Weather Contracts – to address weather and energy risks. The Company may purchase or sell contracts with financial settlements based on the performance of an index linked to a quantifiable weather element, such as temperature, precipitation, snowfall or windspeed, and structures with multiple risk triggers indexed to a quantifiable weather element and a weather sensitive commodity price, such as temperature and electrical power or natural gas. Generally, the Company’s current portfolio of energy and weather derivative contracts is of comparably short duration and such contracts are predominantly seasonal in nature.
	7	Derivatives, cont'd.
	The fair values and the related notional values of derivatives at September 30, 2014 and December 31, 2013 are shown below.
		30-Sep-14						31-Dec-13
		Fair			Notional			Fair			Notional
		Value			Principal			Value			Principal
					Amount						Amount
	Derivatives recorded in other assets
	Foreign exchange forward contracts	$	1,128		$	40,923		$	251		$	19,269
	Credit default swaps	11			1,785			—			—
	Interest rate swaps	211			72,700			124			16,100
	Interest rate swaptions	—			—			39			24,338
	TBAs	131,316			127,255			93,820			93,840
	Energy and weather contracts	14,822			79,846			14,038			53,986
	Total recorded in other assets	$	147,488					$	108,272
	Derivatives recorded in other liabilities
	Foreign exchange forward contracts	$	312		$	23,641		$	172		$	15,861
	Interest rate swaps	731			11,782			933			12,193
	Interest rate swaptions	18			56,216			543			361,455
	Interest rate futures	—			—			17			103,935
	TBAs	78,727			76,000			28,218			28,000
	Energy and weather contracts	15,916			115,574			19,569			66,113
	Total recorded in other liabilities	$	95,704					$	49,452
	Net derivative asset	$	51,784					$	58,820
	7	Derivatives, cont'd.
	At September 30, 2014, the Company’s derivative assets of $147.5 million (December 31, 2013 - $108.3 million) and liabilities of $95.7 million (December 31, 2013 - $49.4 million) are subject to master netting agreements, which provide for the ability to settle the derivative asset and liability with each counterparty on a net basis. Interest rate futures are not subject to a master netting agreement. At September 30, 2014 and December 31, 2013, none of the Company’s derivative instruments were recorded on a net basis in the Condensed Consolidated Balance Sheets.
	The gains and losses on the Condensed Consolidated Statements of Income and Comprehensive Income for derivatives for the three and nine months ended September 30, 2014 and 2013 were as follows:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Total included in net foreign exchange losses from foreign exchange forward contracts	$	1,214		$	(123	)	$	815		$	207
	Futures contracts	$	—		$	112		$	136		$	64
	Credit default swaps	6			(68		)	20			49
	Interest rate swaps	384			(67		)	(698		)	(228		)
	Interest rate swaptions	(3		)	392			425			291
	TBAs	193			(11		)	2,649			(476		)
	Total included in net realized and unrealized investment gains (losses)	$	580		$	358		$	2,532		$	(300	)
	Total included in other underwriting income (loss) from energy and weather contracts	$	1,784		$	—		$	1,486		$	1,172
	Total gains from derivatives	$	3,578		$	235		$	4,833		$	1,079

StockBased_Employee_Compensati

Stock-Based Employee Compensation And Other Stock Plans	9 Months Ended
	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stock-Based Employee Compensation And Other Stock Plans	'
	8	Stock-based employee compensation and other stock plans
	The Company has a stock-based employee compensation plan, which provides the Company with the ability to grant options to purchase the Company’s ordinary shares, share appreciation rights, restricted shares, share bonuses and other equity incentive awards to key employees.
	No options were granted, expired, vested or exercised during the quarters ended September 30, 2014 and 2013. For the quarter ended September 30, 2014, compensation costs recognized in earnings for all options totaled $0.6 million (2013 - $1.0 million). At September 30, 2014, compensation costs not yet recognized related to unvested stock options was $3.2 million (2013 - $6.7 million).
	No options were granted or expired during the nine months ended September 30, 2014. During the nine months ended September 30, 2013, 800,000 options were granted with a weighted average grant date fair value of $10.2 million. The Company uses the Black-Scholes-Merton formula to estimate the value of stock options granted. No options expired during the nine months ended September 30, 2013. During the nine months ended September 30, 2014, 15,000 (2013 - 24,501) options were exercised. During the nine months ended September 30, 2014, 160,000 (2013 - 160,000) options vested. The total intrinsic value of options exercised during the nine months ended September 30, 2014 was $0.3 million (2013 - $0.5 million). The Company received proceeds of $0.5 million (2013 - $0.6 million) from the exercise of options during the nine months ended September 30, 2014. The Company issued new ordinary shares in connection with the exercise of the above options. For the nine months ended September 30, 2014, compensation costs recognized in earnings for all options totaled $2.5 million (2013 - $3.5 million).
	8	Stock-based employee compensation and other stock plans, cont'd.
	During the quarter ended September 30, 2014, the Company granted an aggregate of 39,080 (2013 – 8,453) restricted shares with weighted average grant date fair values of $2.1 million (2013 - $0.4 million). During the quarter ended September 30, 2014, the aggregate fair value of restricted shares and restricted share units that vested was $0.2 million (2013 - $0.1 million). For the quarter ended September 30, 2014, compensation costs recognized in earnings for all restricted shares and restricted share units were $5.7 million (2013 - $2.6 million). At September 30, 2014, compensation costs not yet recognized related to unvested restricted shares and restricted share units was $27.7 million (2013 - $31.6 million).
	During the nine months ended September 30, 2014, the Company granted an aggregate of 472,497 (2013 – 1,079,108) restricted shares and restricted share units with weighted average grant date fair values of $24.8 million (2013 - $50.7 million). During the nine months ended September 30, 2014, the aggregate fair value of restricted shares and restricted share units that vested was $18.7 million (2013 - $17.0 million). For the nine months ended September 30, 2014, compensation costs recognized in earnings for all restricted shares and restricted share units were $21.5 million (2013 - $16.1 million).
	The Company also has an Employee Share Purchase Plan under which employees of Endurance Holdings and certain of its subsidiaries may purchase Endurance Holdings’ ordinary shares. For the quarter ended September 30, 2014, total expenses related to the Company’s Employee Share Purchase Plan were approximately $62,000 (2013- $42,000) and $172,000 (2013 - $124,000) for the nine months ended September 30, 2014.

Segment_Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Segment Reporting	'
	9	Segment reporting
	The determination of the Company’s business segments is based on how the Company monitors the performance of its underwriting operations. The Company has two reportable business segments, Insurance and Reinsurance, which are comprised of the following lines of business:
	Insurance segment lines of business
	•Agriculture
	•Casualty and other specialty
	•Professional lines
	•Property
	Reinsurance segment lines of business
	•Catastrophe
	•Property
	•Casualty
	•Professional lines
	•Specialty
	Management measures segment results on the basis of the combined ratio, which is obtained by dividing the sum of the net losses and loss expenses, acquisition expenses and general and administrative expenses by net premiums earned. When purchased within a single line of business, ceded reinsurance and recoveries are accounted for within that line of business. When purchased across multiple lines of business, ceded reinsurance and recoveries are allocated to the lines of business in proportion to the related risks assumed. The Company does not manage its assets by segment; accordingly, investment income and total assets are not allocated to the individual business segments. General and administrative expenses incurred by the segments are allocated directly. Remaining general and administrative expenses not directly incurred by the segments are allocated primarily based on estimated consumption, headcount and other variables deemed relevant to the allocation of such expenses. Ceded reinsurance and recoveries are recorded within the business segment to which they apply.
	9	Segment reporting, cont'd.
	The following table provides a summary of segment revenues, results and reserves for losses and loss expenses for the three months ended September 30, 2014:
		Three Months Ended September 30, 2014
		Insurance			Reinsurance			Total
	Revenues
	Gross premiums written	$	420,343		$	205,767		$	626,110
	Ceded premiums written	(222,704		)	(13,300		)	(236,004		)
	Net premiums written	197,639			192,467			390,106
	Net premiums earned	253,583			261,312			514,895
	Other underwriting income	—			2,123			2,123
		253,583			263,435			517,018
	Expenses
	Net losses and loss expenses	196,677			93,592			290,269
	Acquisition expenses	20,170			73,222			93,392
	General and administrative expenses	44,957			35,958			80,915
		261,804			202,772			464,576
	Underwriting (loss) income	$	(8,221	)	$	60,663		$	52,442
	Net loss ratio	77.5		%	35.8		%	56.4		%
	Acquisition expense ratio	8		%	28		%	18.1		%
	General and administrative expense ratio	17.7		%	13.8		%	15.7		%
	Combined ratio	103.2		%	77.6		%	90.2		%
	Reserve for losses and loss expenses	$	2,134,985		$	1,762,498		$	3,897,483
	9	Segment reporting, cont'd.
	The following table provides a summary of segment revenues, results and reserves for losses and loss expenses for the three months ended September 30, 2013:
		Three Months Ended September 30, 2013
		Insurance			Reinsurance			Total
	Revenues
	Gross premiums written	$	344,819		$	199,544		$	544,363
	Ceded premiums written	(120,481		)	(28,549		)	(149,030		)
	Net premiums written	224,338			170,995			395,333
	Net premiums earned	291,477			262,068			553,545
	Other underwriting loss	—			(943		)	(943		)
		291,477			261,125			552,602
	Expenses
	Net losses and loss expenses	228,409			110,627			339,036
	Acquisition expenses	18,440			60,335			78,775
	General and administrative expenses	35,641			31,829			67,470
		282,490			202,791			485,281
	Underwriting income	$	8,987		$	58,334		$	67,321
	Net loss ratio	78.4		%	42.3		%	61.3		%
	Acquisition expense ratio	6.3		%	23		%	14.2		%
	General and administrative expense ratio	12.2		%	12.1		%	12.2		%
	Combined ratio	96.9		%	77.4		%	87.7		%
	Reserve for losses and loss expenses	$	2,146,136		$	1,905,966		$	4,052,102
	The following table reconciles total segment results to income before income taxes for the three months ended September 30, 2014 and 2013:
		Three Months Ended September 30,
		2014			2013
	Total underwriting income	$	52,442		$	67,321
	Net investment income	25,357			38,097
Net foreign exchange losses	(783		)	(2,201		)
Net realized and unrealized investment gains (losses)	9,788			(6,640		)
Net impairment losses recognized in earnings	(102		)	(190		)
Amortization of intangibles	(1,623		)	(1,652		)
Interest expense	(13,127		)	(9,048		)
Income before income taxes	$	71,952		$	85,687
9	Segment reporting, cont'd.
The following table provides gross and net premiums written by line of business for the three months ended September 30, 2014 and 2013:
	Gross			Net			Gross			Net
	premiums			premiums			premiums			premiums
	written			written			written			written
Business Segment	2014			2014			2013			2013
Insurance
Agriculture	$	188,011		$	103,536		$	200,062		$	120,617
Casualty and other specialty	144,706			58,390			95,862			72,431
Professional lines	62,631			20,216			34,221			20,972
Property	24,995			15,497			14,674			10,318
Total Insurance	420,343			197,639			344,819			224,338
Reinsurance
Catastrophe	47,173			41,157			38,676			12,551
Property	73,807			73,807			91,653			90,528
Casualty	23,409			23,409			27,649			27,648
Professional lines	21,520			21,520			25,670			25,670
Specialty	39,858			32,574			15,896			14,598
Total Reinsurance	205,767			192,467			199,544			170,995
Total	$	626,110		$	390,106		$	544,363		$	395,333
The following table provides a summary of the segment revenues and results for the nine months ended September 30, 2014:
	Nine Months Ended September 30, 2014
	Insurance			Reinsurance			Total
Revenues
Gross premiums written	$	1,394,145		$	1,078,905		$	2,473,050
Ceded premiums written	(674,441		)	(98,371		)	(772,812		)
Net premiums written	719,704			980,534			1,700,238
Net premiums earned	616,167			776,532			1,392,699
Other underwriting loss	—			(3,939		)	(3,939		)
	616,167			772,593			1,388,760
Expenses
Net losses and loss expenses	434,777			291,584			726,361
Acquisition expenses	47,559			196,591			244,150
General and administrative expenses	133,930			106,646			240,576
	616,266			594,821			1,211,087
Underwriting (loss) income	$	(99	)	$	177,772		$	177,673
Net loss ratio	70.6		%	37.6		%	52.2		%
Acquisition expense ratio	7.7		%	25.3		%	17.5		%
General and administrative expense ratio	21.7		%	13.7		%	17.3		%
Combined ratio	100		%	76.6		%	87		%
9	Segment reporting, cont'd.
The following table provides a summary of the segment revenues and results for the nine months ended September 30, 2013:
	Nine Months Ended September 30, 2013
	Insurance			Reinsurance			Total
Revenues
Gross premiums written	$	1,274,703		$	1,019,732		$	2,294,435
Ceded premiums written	(454,169		)	(71,397		)	(525,566		)
Net premiums written	820,534			948,335			1,768,869
Net premiums earned	710,507			806,490			1,516,997
Other underwriting income	—			694			694
	710,507			807,184			1,517,691
Expenses
Net losses and loss expenses	543,717			373,347			917,064
Acquisition expenses	48,024			174,255			222,279
General and administrative expenses	114,792			100,515			215,307
	706,533			648,117			1,354,650
Underwriting income	$	3,974		$	159,067		$	163,041
Net loss ratio	76.4		%	46.3		%	60.4		%
Acquisition expense ratio	6.8		%	21.6		%	14.7		%
General and administrative expense ratio	16.2		%	12.5		%	14.2		%
Combined ratio	99.4		%	80.4		%	89.3		%
The following table reconciles total segment results to income before income taxes for the nine months ended September 30, 2014 and 2013, respectively:
	Nine Months Ended September 30,
	2014			2013
Total underwriting income	$	177,673		$	163,041
Net investment income	105,649			119,870
Net foreign exchange losses	(4,066		)	(8,496		)
Net realized and unrealized investment gains	18,071			9,967
Net impairment losses recognized in earnings	(411		)	(1,575		)
Amortization of intangibles	(4,863		)	(5,378		)
Interest expense	(31,910		)	(27,138		)
Income before income taxes	$	260,143		$	250,291
9	Segment reporting, cont'd.
The following table provides gross and net premiums written by line of business for the nine months ended September 30, 2014 and 2013:
	Gross			Net			Gross			Net
	premiums			premiums			premiums			premiums
	written			written			written			written
Business Segment	2014			2014			2013			2013
Insurance
Agriculture	$	796,445		$	431,007		$	896,169		$	546,284
Casualty and other specialty	366,329			189,876			239,943			179,065
Professional lines	176,061			64,632			93,481			62,963
Property	55,310			34,189			45,110			32,222
Total Insurance	1,394,145			719,704			1,274,703			820,534
Reinsurance
Catastrophe	332,193			243,531			341,973			281,990
Property	283,107			283,015			288,448			283,455
Casualty	139,266			137,669			211,458			210,030
Professional lines	131,256			131,256			50,505			50,505
Specialty	193,083			185,063			127,348			122,355
Total Reinsurance	1,078,905			980,534			1,019,732			948,335
Total	$	2,473,050		$	1,700,238		$	2,294,435		$	1,768,869

Commitments_And_Contingencies

Commitments And Contingencies	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments And Contingencies	'
	10	Commitments and contingencies
	Concentrations of credit risk. The Company’s reinsurance recoverables on paid and unpaid losses at September 30, 2014 and December 31, 2013 amounted to $731.9 million and $758.0 million, respectively. At September 30, 2014, substantially all reinsurance recoverables on paid and unpaid losses were due from the U.S. government or from reinsurers rated A- or better by A.M. Best Company Inc. or Standard & Poor’s Corporation. At September 30, 2014 and December 31, 2013, the Company held collateral of $87.6 million and $14.2 million, respectively, related to its ceded reinsurance agreements.
	Major production sources. The following table shows the percentage of net premiums written generated through the Company’s largest brokers for the nine months ended September 30, 2014 and 2013, respectively:
	Broker		2014		2013
	Marsh & McLennan Companies, Inc.		20.9	%	15	%
	Aon Benfield		15.4	%	18.5	%
	Willis Companies		14.2	%	12.4	%
	Total of largest brokers		50.5	%	45.9	%
	Letters of credit. As of September 30, 2014, the Company had issued letters of credit of $202.9 million (December 31, 2013 – $260.3 million) under its credit facility in favor of certain ceding companies to collateralize obligations.
	On January 17, 2014, the Company and certain designated subsidiaries of the Company entered into a $50.0 million revolving letter of credit reimbursement agreement (“LOC Agreement”) and cash collateral agreement with Australia and New Zealand Banking Group Limited. As of September 30, 2014, the Company had issued letters of credit of $1.4 million (December 31, 2013 - nil) under the LOC Agreement. For letters of credit issued under the LOC Agreement, the Company is required to pay a fee that is negotiated at the time of issuance of the letter of credit. Letters of credit issued under the LOC Agreement are required to be collateralized with cash or investments.
	10	Commitments and contingencies, cont'd.
	Agreement with Equity Investors. On June 2, 2014, the Company entered into an agreement (the “Agreement”) terminating a prior equity commitment letter, dated January 28, 2014. In connection with such termination, the Company extended to CVC Capital Partners Advisory (U.S.), Inc. (“CVC”) and certain permitted assignees of CVC (collectively, the “Equity Option Investors”) an equity investment option in the event that, on or prior to December 31, 2014, the Company enters into a definitive written agreement to acquire, or acquires, 95% or more of the issued and outstanding Aspen Insurance Holdings Limited (“Aspen”) ordinary shares (the “Equity Investment Option”). Pursuant to the Equity Investment Option, if exercised, the Equity Option Investors would purchase $250.0 million of newly issued Company ordinary shares at a price of $50.03 per ordinary share, as adjusted for any stock splits, stock dividends or combinations prior to the closing of the Equity Investment Option. The Equity Investment Option would be exercisable for the sixty (60) day period following the closing of the Company’s proposed acquisition of Aspen.
	The Equity Option Investors would have certain preemptive rights with respect to future share issuances by the Company, and the purchased ordinary shares would be subject to lock-up restrictions that would limit the right of the Equity Option Investors to transfer the shares for 12 months following the exercise of the Equity Investment Option, subject to certain exceptions.
	In addition to the purchase of Company ordinary shares, upon the closing of the Equity Investment Option, the Company would also grant the Equity Option Investors, on a pro rata basis, warrants to purchase a number of additional Company ordinary shares equal to 38.5% of the total number of Company ordinary shares acquired by the Equity Option Investors in connection with the Equity Investment Option, at an exercise price equal to $58.86 per share, as adjusted for any stock splits, stock dividends or combinations prior to the closing of the Equity Investment Option. The warrants would have a term of 10 years from the date of the closing of the Equity Investment Option.
	Upon the closing of the Equity Investment Option, CVC would have the right to nominate one individual to serve as a director of the Company, which individual shall qualify as an independent director for purposes of the NYSE rules and, except for two specified individuals, shall be subject to the approval of the Company’s board of directors (such approval not to be unreasonably withheld).
	Pursuant to the Agreement, the Company also granted the Equity Option Investors a right of first refusal in the event the Company proposes to raise, on a private basis, equity capital through the sale of equity securities or securities convertible into or exchangeable or exercisable for equity securities of the Company or other equity-linked securities, the purpose of which is to partially fund the cash portion of an acquisition of Aspen completed, or for which a definitive written agreement is entered into, on or prior to December 31, 2014, or to refinance any debt incurred by the Company in connection with any such acquisition (only to the extent the proceeds of any such refinancing are specifically earmarked for such purposes). This right of first refusal is subject to certain exceptions, including with respect to equity purchased by the Company’s Chief Executive Officer of up to $25.0 million and by certain other specified equity investors of up to $100.0 million. The Company does not currently intend to raise any equity capital that would be subject to the right of first refusal, but reserves the right to do so.
	The Company has also agreed that, in the event any person or entity (other than certain funds advised by CVC or their affiliates) enters into a definitive written agreement to acquire or acquires more than 40% of the capital stock of the Company on or prior to December 31, 2014, the Company will pay CVC an amount equal to $26.3 million upon the closing of such transaction, less the amount of any previously reimbursed expenses.
	The Charman Agreement. John R. Charman, the Company’s Chief Executive Officer, and the Company entered into an agreement on June 2, 2014, pursuant to which Mr. Charman committed to purchase, subject to the receipt of any required regulatory approvals and the completion of the Company’s acquisition of Aspen, $25.0 million of newly issued Company common shares at a price per share equal to $53.51, as adjusted for any stock splits, stock dividends or combinations prior to the closing of such investment.
	10	Commitments and contingencies, cont'd.
	Investment commitments. As of September 30, 2014 and December 31, 2013, the Company had pledged cash and cash equivalents and fixed maturity investments of $130.1 million and $146.1 million, respectively, in favor of certain ceding companies to collateralize obligations. As of September 30, 2014 and December 31, 2013, the Company had also pledged $237.9 million and $302.7 million of its cash and fixed maturity investments as required to meet collateral obligations for $202.9 million and $260.3 million, respectively, in letters of credit outstanding under its credit facility and LOC Agreement. In addition, as of September 30, 2014 and December 31, 2013, cash and fixed maturity investments with fair values of $273.1 million and $273.7 million were on deposit with U.S. state regulators, respectively.
	The Company is subject to certain commitments with respect to other investments at September 30, 2014 and December 31, 2013. See Note 3.
	Reinsurance commitments. In the ordinary course of business, the Company periodically enters into reinsurance agreements that include terms which could require the Company to collateralize certain of its obligations.
	Employment agreements. The Company has entered into employment agreements with certain officers that provide for equity incentive awards, executive benefits and severance payments under certain circumstances.
	Operating leases. The Company leases office space and office equipment under operating leases. Future minimum lease commitments at September 30, 2014 are as follows:
	Twelve months ended September 30,		Amount
	2015		$	16,066
	2016		13,527
	2017		11,957
	2018		11,465
	2019		10,809
	2020 and thereafter		36,377
			$	100,201
	Total net lease expense under operating leases for the nine months ended September 30, 2014 was $11.6 million (2013 – $11.2 million).
	Legal proceedings. The Company is party to various legal proceedings generally arising in the normal course of its business. While any proceeding contains an element of uncertainty, the Company does not believe that the eventual outcome of any litigation or arbitration proceeding to which it is presently a party could have a material adverse effect on its financial condition or business. Pursuant to the Company’s insurance and reinsurance agreements, disputes are generally required to be settled by arbitration.

Debt_And_Financing_Arrangement

Debt And Financing Arrangements	9 Months Ended
	Sep. 30, 2014
Debt Instruments [Abstract]	'
Debt Disclosure [Text Block]	'
	11	Debt
	On April 19, 2012, the Company and certain designated subsidiaries of the Company entered into a $700.0 million four-year revolving credit facility with JPMorgan Chase Bank, N.A. (“JPMorgan”) as administrative agent (“Credit Facility”). As of September 30, 2014, there were no borrowings under this facility and letters of credit outstanding under the Credit Facility were $202.9 million (December 31, 2013 – $260.3 million).
	On June 25, 2014, the Company entered into the First Amendment (the “Amendment”) to the Credit Facility. The Amendment also amends the Security Agreement, dated as of April 19, 2012 (the “Security Agreement”), among the Company and various designated subsidiaries of the Company, Deutsche Bank Trust Company America, as collateral agent, and JPMorgan. The Amendment contained certain amendments to the Credit Facility and the Security Agreement applicable to the proposed acquisition of Aspen.
	11	Debt, cont'd.
	On June 2, 2014, the Company entered into a commitment letter with Morgan Stanley Senior Funding, Inc. (the “Commitment Letter”). Pursuant to the Commitment Letter, Morgan Stanley Senior Funding, Inc., as lead arranger, committed to provide to the Company, subject to certain conditions, senior unsecured bank financing of up to $1.0 billion under an unsecured 364-day bridge facility (the “Bridge Facility”), which was to be used to finance a portion of the cash consideration to be paid in connection with the Company’s proposed acquisition of Aspen and related costs and expenses. Upon the termination by the Company of its offer to acquire Aspen on July 30, 2014, the Bridge Facility expired pursuant to its terms.

Summary_Of_Significant_Account1

Summary Of Significant Accounting Policies (Policy)	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
New Accounting Pronouncements Adopted	'
	In July 2013, the FASB issued ASU 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”). ASU 2013-11 provides guidance on the presentation of unrecognized tax benefits to better reflect the manner in which an entity would settle at the reporting date any additional income taxes that would result from the disallowance of a tax position when net operating loss carryforwards, similar tax losses, or tax credit carryforwards exist. ASU 2013-11 was effective for annual and interim reporting periods beginning after December 15, 2013, with both early adoption and retrospective application permitted. The Company adopted this standard effective January 1, 2014. This standard did not have a material impact on the Company’s consolidated financial statements.

Investments_Policy

Investments (Policy)	9 Months Ended
	Sep. 30, 2014
Investments [Abstract]	'
Other Investments	'
	In addition to the Company’s fixed maturity, short-term and equity investments, the Company invests in (i) hedge funds and private investment funds that generally invest in senior secured bank debt, high yield credit, distressed debt, distressed real estate, derivatives, and equity long/short strategies (“alternative funds”) and (ii) high yield loan and convertible debt funds (“specialty funds”). The Company’s alternative funds and specialty funds are recorded on the Company’s balance sheet as “other investments.”
Gain Loss On Investments	'
	Realized and unrealized investment gains and losses are recognized in earnings using the first in, first out method.
Variable Interest Entities	'
	Entities that do not have sufficient equity at risk to allow the entity to finance its activities without additional financial support or in which the equity investors, as a group, do not have the characteristics of a controlling financial interest are referred to as variable interest entities (“VIE”). A VIE is consolidated by the variable interest holder that is determined to have the controlling financial interest (primary beneficiary) as a result of having both the power to direct the activities of a VIE that most significantly impact the VIE’s economic performance and the obligation to absorb losses or right to receive benefits from the VIE that could potentially be significant to the VIE. The Company determines whether it is the primary beneficiary of an entity subject to consolidation based on a qualitative assessment of the VIE’s capital structure, contractual terms, nature of the VIE’s operations and purpose and the Company’s relative exposure to the related risks of the VIE on the date it becomes initially involved in the VIE. The Company reassesses its VIE determination with respect to an entity on an ongoing basis.
	The Company is involved in the normal course of business with VIEs primarily as a passive investor in residential and commercial mortgage-backed securities and through its interests in various other investments that are structured as limited partnerships considered to be third party VIEs. The Company determined that it was not the primary beneficiary for any of these investments as of September 30, 2014. The Company believes its exposure to loss with respect to these investments is generally limited to the investment carrying amounts reported in the Company’s Condensed Consolidated Balance Sheets and any unfunded investment commitments.

Fair_Value_Measurement_Policy

Fair Value Measurement (Policy)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Of Financial Instruments	'
	The Company determines the fair value of the fixed maturity investments, short-term investments, equity securities, other investments, debt, and other assets and liabilities in accordance with current accounting guidance, which defines fair value and establishes a fair value hierarchy based on inputs to the various valuation techniques used for each fair value measurement. The Company determines the estimated fair value of each individual security utilizing the highest level inputs available. Valuation inputs by security type may include the following:
	•	Government and agencies fixed maturity securities – These securities are generally priced by pricing services or index providers. The pricing services or index providers may use current market trades for securities with similar quality, maturity and coupon. If no such trades are available, the pricing service typically uses analytical models which may incorporate option adjusted spreads, daily interest rate data and market/sector news. The Company generally classifies the fair values of government and agencies securities in Level 2. Current issue U.S. government securities are generally valued based on Level 1 inputs, which use the market approach valuation technique.
	•	Government guaranteed corporate fixed maturity securities – These securities are generally priced by pricing services or index providers. The pricing service or index providers may use current market trades for securities with similar quality, maturity and coupon. If no such trades are available, the pricing service typically uses analytical spread models which may incorporate inputs from the U.S treasury curve or LIBOR. The Company generally classifies the fair values of its government guaranteed corporate securities in Level 2.
	•	Corporate fixed maturity securities – These securities are generally priced by pricing services or index providers. The pricing services or index providers typically use discounted cash flow models that incorporate benchmark curves for treasury, swap and high issuance credits. Credit spreads are developed from current market observations for like or similar securities. The Company generally classifies the fair values of its corporate securities in Level 2.
	•	Equity securities – These securities are generally priced by pricing services or index providers. Depending on the type of underlying equity security or equity fund, the securities are priced by pricing services or index providers based on quoted market prices in active markets or through a discounted cash flow model that incorporates benchmark curves for treasury, swap and credits for like or similar securities. The Company generally classifies the fair values of its equity securities in Level 1 or 2.
	•	Other assets and liabilities – A portion of other assets and liabilities are composed of a variety of derivative instruments used to enhance the efficiency of the investment portfolio and economically hedge certain risks. These instruments are generally priced by pricing services, broker/dealers and/or recent trading activity. The market value approach valuation technique is used to estimate the fair value for these derivatives based on significant observable market inputs. Certain derivative instruments are priced by pricing services based on quoted market prices in active markets. These derivative instruments are generally classified in Level 1. Other derivative instruments are priced using industry valuation models and are considered Level 2, as the inputs to the valuation model are based on observable market inputs. Also included in this line item are proprietary, non-exchange traded derivative-based risk management products primarily used to address weather and energy risks. The trading market for these weather derivatives are generally linked to energy and agriculture commodities, weather and other natural phenomena. In instances where market prices are not available, the Company uses industry or internally developed valuation techniques such as spread option, Black Scholes, quanto and simulation modeling to determine fair value and classifies these in Level 3. These models may reference prices for similar instruments.
	•	Structured securities including agency and non-agency, residential and commercial, mortgage and asset-backed securities and collateralized loan and debt obligations – These securities are generally priced by broker/dealers. Broker/dealers may use current market trades for securities with similar qualities. If no such trades are available, inputs such as bid and offer, prepayment speeds, the U.S. treasury curve, swap curve and cash settlement may be used in a discounted cash flow model to determine the fair value of a security. The Company generally classifies the fair values of its structured securities in Level 2.
	4	Fair value measurement, cont'd.
	•	Other investments – Other investments are comprised of alternative funds and specialty funds and are generally priced on net asset values (“NAV”) received from the fund managers or administrators. Due to the timing of the delivery of the final NAV by certain of the fund managers, valuations of certain alternative funds and specialty funds are estimated based on the most recently available information, including period end NAVs, period end estimates, or, in some cases, prior month or prior quarter NAVs. As this valuation technique incorporates both observable and significant unobservable inputs, the Company generally classifies the fair value of its other investments in Level 3.
	•	Debt – Outstanding debt consists of the Company’s 6.15% Senior Notes due October 15, 2015 and the 7.0% Senior Notes due July 15, 2034 (the “Senior Notes”). The fair values of these securities were obtained from a third party pricing service and pricing was based on the spread above the risk-free yield curve. These spreads are generally obtained from the new issue market, secondary trading and broker-dealer quotes. As these spreads and the yields for the risk-free yield curve are observable market inputs, the fair values of the Senior Notes are classified in Level 2.
	The carrying values of cash and cash equivalents, accrued investment income, net receivable on sales of investments, net payable on purchases of investments and other financial instruments not described above approximated their fair values at September 30, 2014.
Fair Value Transfer Between Levels	'
	Transfers between levels are assumed to occur at the end of each period.

Earnings_Per_Share_Policy

Earnings Per Share (Policy)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	The two-class method utilized by the Company is an earnings allocation formula that determines earnings per share for the holders of Endurance Holdings’ ordinary shares (also referred to as “common shares”) and participating common shares, which includes unvested restricted shares that receive cash dividends, according to dividends declared and participation rights in undistributed earnings. Net income available to common and participating common shareholders is reduced by the amount of dividends declared in the current period and by the contractual amount of dividends that must be paid for the current period related to the Company’s common and participating common shares. Any remaining undistributed earnings are allocated to the common and participating common shareholders to the extent that each security may share in earnings as if all of the earnings for the period had been distributed. In periods of loss, no losses are allocated to participating common shareholders. Instead, all such losses are allocated solely to the common shareholders.
	Basic earnings per common share are calculated by dividing net income available to common shareholders by the weighted average number of common shares outstanding. The weighted average number of common shares excludes any dilutive effect of outstanding options and convertible securities such as unvested restricted shares.
	Diluted earnings per common share are based on the weighted average number of common shares and assumes the exercise of all dilutive stock options and the vesting or conversion of all convertible securities such as unvested restricted shares using the two-class method described above.

Derivatives_Policy

Derivatives (Policy)	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Accounting policy for derivatives	'
	The Company regularly transacts in certain derivative-based weather risk management products primarily to address weather and energy risks on behalf of third parties. The markets for these derivatives are generally linked to energy and agriculture commodities, weather and other natural phenomena. Generally, the Company’s current portfolio of such derivative contracts is of short duration and such contracts are predominantly seasonal in nature. The Company also invests a portion of its fixed maturity assets with third party investment managers with investment guidelines that permit the use of derivative instruments. The Company may enter derivative transactions directly or as part of strategies employed by its external investment managers.
	The Company’s derivative instruments are recorded in the Condensed Consolidated Balance Sheets at fair value, with changes in fair value and gains and losses recognized in net realized and unrealized investment gains (losses), net foreign exchange losses and other underwriting income (loss) in the Condensed Consolidated Statements of Income and Comprehensive Income.
	The Company’s derivatives are not designated as hedges under current accounting guidance.
	The Company’s objectives for holding these derivatives are as follows:
	Interest Rate Futures, Swaps, Swaptions and Options - to manage exposure to interest rate risk, which can include increasing or decreasing its exposure to this risk through modification of the portfolio composition and duration.
	Foreign Exchange Forwards, Futures and Options - as part of overall currency risk management and investment strategies.
	Credit Default Swaps - to manage market exposures. The Company may assume or economically hedge credit risk through credit default swaps to replicate or hedge investment positions. The original term of these credit default swaps is generally five years or less.
	To-Be-Announced Mortgage-backed Securities (“TBAs”) - to enhance investment performance and as part of overall investment strategy. TBAs represent commitments to purchase or sell a future issuance of agency mortgage-backed securities. For the period between purchase of a TBA and issuance of the underlying securities, the Company’s position is accounted for as a derivative.
	Energy and Weather Contracts – to address weather and energy risks. The Company may purchase or sell contracts with financial settlements based on the performance of an index linked to a quantifiable weather element, such as temperature, precipitation, snowfall or windspeed, and structures with multiple risk triggers indexed to a quantifiable weather element and a weather sensitive commodity price, such as temperature and electrical power or natural gas. Generally, the Company’s current portfolio of energy and weather derivative contracts is of comparably short duration and such contracts are predominantly seasonal in nature.
Offsetting of derivatives policy	'
	At September 30, 2014 and December 31, 2013, none of the Company’s derivative instruments were recorded on a net basis in the Condensed Consolidated Balance Sheets.

Segment_Reporting_Policy

Segment Reporting (Policy)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Segment Reporting	'
	The determination of the Company’s business segments is based on how the Company monitors the performance of its underwriting operations. The Company has two reportable business segments, Insurance and Reinsurance, which are comprised of the following lines of business:
	Insurance segment lines of business
	•Agriculture
	•Casualty and other specialty
	•Professional lines
	•Property
	Reinsurance segment lines of business
	•Catastrophe
	•Property
	•Casualty
	•Professional lines
	•Specialty
	Management measures segment results on the basis of the combined ratio, which is obtained by dividing the sum of the net losses and loss expenses, acquisition expenses and general and administrative expenses by net premiums earned. When purchased within a single line of business, ceded reinsurance and recoveries are accounted for within that line of business. When purchased across multiple lines of business, ceded reinsurance and recoveries are allocated to the lines of business in proportion to the related risks assumed. The Company does not manage its assets by segment; accordingly, investment income and total assets are not allocated to the individual business segments. General and administrative expenses incurred by the segments are allocated directly. Remaining general and administrative expenses not directly incurred by the segments are allocated primarily based on estimated consumption, headcount and other variables deemed relevant to the allocation of such expenses. Ceded reinsurance and recoveries are recorded within the business segment to which they apply.

Investments_Tables

Investments (Tables)	9 Months Ended
	Sep. 30, 2014
Investments [Abstract]	'
Composition Of Net Investment Income	'
		Three Months Ended September 30,							Nine Months Ended September 30,
		2014			2013				2014				2013
	Available for sale investments	$	29,959		$	27,889			$	91,905			$	86,036
	Other investments	(1,785		)	13,244				22,542				43,083
	Cash and cash equivalents	581			752				1,878				2,043
		$	28,755		$	41,885			$	116,325			$	131,162
	Investment expenses	(3,398		)	(3,788		)		(10,676		)		(11,292		)
	Net investment income	$	25,357		$	38,097			$	105,649			$	119,870
Composition of the Investment Portfolio by Investment Type	'
			30-Sep-14						31-Dec-13
	Type of Investment		Fair Value			Percentage			Fair Value				Percentage
	Fixed maturity investments		$	4,871,420		75.4	%		$	4,823,964			74.2	%
	Cash and cash equivalents (1)		652,377			10.1	%		771,714				11.9	%
	Other investments (2)		658,678			10.2	%		617,478				9.5	%
	Short-term investments		11,844			0.2	%		35,028				0.5	%
	Equity securities		267,728			4.1	%		252,466				3.9	%
	Total		$	6,462,047		100	%		$	6,500,650			100	%
	-1	Includes net receivable on sales of investments and net payable on purchases of investments.
	-2	Consists of investments in alternative funds and specialty funds.
Composition Of Fixed Income Portfolio, Including Fixed Maturity Investments And Short-Term Investments, By Investment Ratings	'
		30-Sep-14						31-Dec-13
	Ratings (1)	Fair Value			Percentage			Fair Value				Percentage
	U.S. government and agencies securities	$	514,672		10.5	%		$	769,343			15.8	%
	AAA / Aaa	1,153,558			23.7	%		972,820				20	%
	AA / Aa	1,738,964			35.7	%		1,771,156				36.5	%
	A / A	952,894			19.5	%		895,549				18.4	%
	BBB	407,093			8.3	%		363,722				7.5	%
	Below BBB	94,824			1.9	%		66,791				1.4	%
	Not rated	21,259			0.4	%		19,611				0.4	%
	Total	$	4,883,264		100	%		$	4,858,992			100	%
	-1	The credit rating for each security reflected above was determined based on the rating assigned to the individual security by Standard & Poor's Financial Services LLC ("Standard & Poor's"). If a rating is not supplied by Standard & Poor's, the equivalent rating supplied by Moody's Investors Service, Inc. ("Moody's"), Fitch Ratings, Inc., or DBRS, Inc. is used.
Contractual Maturities Of Fixed Maturity And Short-Term Investments	'
		30-Sep-14							31-Dec-13
		Amortized			Fair Value				Amortized				Fair Value
		Cost							Cost
	Due within one year	$	128,535		$	129,382			$	144,814			$	145,653
	Due after one year through five years	1,575,875			1,583,414				1,808,001				1,815,240
	Due after five years through ten years	339,764			341,993				290,391				288,486
	Due after ten years	33,034			35,474				26,344				26,937
	Residential mortgage-backed securities	1,185,911			1,203,322				1,192,085				1,187,191
	Commercial mortgage-backed securities	948,460			965,696				932,263				947,677
	Collateralized loan and debt obligations	205,465			207,214				92,519				94,552
	Asset-backed securities	414,968			416,769				351,192				353,256
	Total	$	4,832,012		$	4,883,264			$	4,837,609			$	4,858,992
Other Investments	'
	30-Sep-14	Market Value			Unfunded				Ineligible for
					Commitments				Redemption over
									next 12 months
	Alternative funds
	Hedge funds	$	431,278		$	—			$	38,900
	Private investment funds	68,433			64,473				68,433
	Total alternative funds	499,711			64,473				107,333
	Specialty funds
	High yield loan funds	112,892			—				—
	Convertible debt funds	46,075			—				—
	Total specialty funds	158,967			—				—
	Total other investments	$	658,678		$	64,473			$	107,333
	31-Dec-13	Market Value			Unfunded				Ineligible for
					Commitments				Redemption in 2014
	Alternative funds
	Hedge funds	$	401,438		$	—			$	47,406
	Private investment funds	59,703			57,997				59,703
	Total alternative funds	461,141			57,997				107,109
	Specialty funds
	High yield loan funds	111,254			—				—
	Convertible debt funds	45,083			—				—
	Total specialty funds	156,337			—				—
	Total other investments	$	617,478		$	57,997			$	107,109
Net Realized And Unrealized Investment Gains (Losses)	'
		Three Months Ended September 30,							Nine Months Ended September 30,
		2014			2013				2014				2013
	Gross realized gains on investment sales	$	10,683		$	6,180			$	28,317			$	30,191
	Gross realized losses on investment sales	(1,475		)	(13,178		)		(12,778		)		(19,924		)
	Change in fair value of derivative financial instruments (1)	580			358				2,532				(300		)
	Net realized and unrealized investment gains (losses)	$	9,788		$	(6,640	)		$	18,071			$	9,967
	-1	For additional information on the Company’s derivative financial instruments, see Note 7.
Amortized Cost, Fair Value, Unrealized Gains and Losses And Non-Credit Other-Then-Temporary Impairments	'
		Amortized			Gross				Gross				Fair Value			Non-Credit
		Cost			Unrealized				Unrealized							OTTI (2)
					Gains				Losses
	31-Dec-13
	Fixed maturity investments
	U.S. government and agencies securities	$	771,227		$	5,735			$	(7,619	)		$	769,343		$	—
	U.S. state and municipal securities	27,138			111				(395		)		26,854			—
	Foreign government securities	183,650			1,003				(2,006		)		182,647			—
	Government guaranteed corporate securities	34,921			274				(50		)		35,145			—
	Corporate securities	1,217,585			16,225				(6,511		)		1,227,299			—
	Residential mortgage-backed securities	1,192,085			17,005				(21,899		)		1,187,191			(4,257		)
	Commercial mortgage-backed securities	932,263			23,423				(8,009		)		947,677			(47		)
	Collateralized loan and debt obligations (1)	92,519			2,233				(200		)		94,552			—
	Asset-backed securities	351,192			2,919				(855		)		353,256			(163		)
	Total fixed maturity investments	$	4,802,580		$	68,928			$	(47,544	)		$	4,823,964		$	(4,467	)
	Short-term investments	35,029			1				(2		)		35,028			—
	Total fixed income investments	$	4,837,609		$	68,929			$	(47,546	)		$	4,858,992		$	(4,467	)
	Equity securities
	Equity investments	$	152,525		$	24,139			$	(1,995	)		$	174,669		$	—
	Emerging market debt funds	60,250			594				—				60,844			—
	Preferred equity investments	6,325			1,977				(79		)		8,223			—
	Short-term fixed income funds	8,728			2				—				8,730			—
	Total equity securities	$	227,828		$	26,712			$	(2,074	)		$	252,466		$	—
	-1	Balances include amounts related to collateralized debt obligations held with total fair values of $18.7 million.
	-2	Represents total OTTI recognized in accumulated other comprehensive income. It does not include the change in fair value subsequent to the impairment measurement date. At December 31, 2013, the gross unrealized loss related to fixed income investments for which a non-credit OTTI was recognized in accumulated other comprehensive income was $0.1 million.
		Amortized			Gross				Gross				Fair Value			Non-Credit
		Cost			Unrealized				Unrealized							OTTI (2)
					Gains				Losses
	30-Sep-14
	Fixed maturity investments
	U.S. government and agencies securities	$	512,199		$	5,450			$	(2,977	)		$	514,672		$	—
	U.S. state and municipal securities	31,437			207				(157		)		31,487			—
	Foreign government securities	204,033			2,033				(373		)		205,693			—
	Government guaranteed corporate securities	45,577			624				—				46,201			—
	Corporate securities	1,272,119			13,037				(4,790		)		1,280,366			—
	Residential mortgage-backed securities	1,185,911			21,984				(4,573		)		1,203,322			(3,319		)
	Commercial mortgage-backed securities	948,460			20,763				(3,527		)		965,696			(5		)
	Collateralized loan and debt obligations (1)	205,465			1,974				(225		)		207,214			—
	Asset-backed securities	414,968			2,333				(532		)		416,769			—
	Total fixed maturity investments	$	4,820,169		$	68,405			$	(17,154	)		$	4,871,420		$	(3,324	)
	Short-term investments	11,843			1				—				11,844			—
	Total fixed income investments	$	4,832,012		$	68,406			$	(17,154	)		$	4,883,264		$	(3,324	)
	Equity securities
	Equity investments	$	157,924		$	26,471			$	(1,881	)		$	182,514		$	—
	Emerging market debt funds	60,250			1,612				—				61,862			—
	Preferred equity investments	12,283			2,071				(37		)		14,317			—
	Short-term fixed income fund	9,030			6				(1		)		9,035			—
	Total equity securities	$	239,487		$	30,160			$	(1,919	)		$	267,728		$	—
	-1	Balances include amounts related to collateralized debt obligations held with total fair values of $10.7 million.
	-2	Represents total OTTI recognized in accumulated other comprehensive income. It does not include the change in fair value subsequent to the impairment measurement date. At September 30, 2014, the gross unrealized loss related to fixed income investments for which a non-credit OTTI was recognized in accumulated other comprehensive income was nil.
Available For Sale Securities In An Unrealized Loss Position	'
		Less than 12 months							12 months or greater							Total
		Unrealized			Fair				Unrealized				Fair			Unrealized			Fair
		Losses			Value				Losses				Value			Losses			Value
	30-Sep-14
	Fixed maturity investments
	U.S. government and agencies securities	$	(559	)	$	95,967			$	(2,418	)		$	95,856		$	(2,977	)	$	191,823
	U.S. state and municipal securities	(78		)	7,261				(79		)		6,835			(157		)	14,096
	Foreign government securities	(204		)	43,104				(169		)		23,314			(373		)	66,418
	Corporate securities	(3,026		)	432,053				(1,764		)		97,104			(4,790		)	529,157
	Residential mortgage-backed securities	(593		)	168,976				(3,980		)		152,520			(4,573		)	321,496
	Commercial mortgage-backed securities	(1,186		)	200,660				(2,341		)		93,769			(3,527		)	294,429
	Collateralized loan and debt obligations	(174		)	95,995				(51		)		1,467			(225		)	97,462
	Asset-backed securities	(264		)	156,553				(268		)		29,991			(532		)	186,544
	Total fixed income investments	$	(6,084	)	$	1,200,569			$	(11,070	)		$	500,856		$	(17,154	)	$	1,701,425
	Equity securities
	Equity investments	$	(1,861	)	$	40,720			$	(20	)		$	141		$	(1,881	)	$	40,861
	Preferred equity investments	(37		)	5,676				—				—			(37		)	5,676
	Short-term fixed income fund	(1		)	2,899				—				—			(1		)	2,899
	Total equity securities	$	(1,899	)	$	49,295			$	(20	)		$	141		$	(1,919	)	$	49,436
		Less than 12 months							12 months or greater							Total
		Unrealized			Fair				Unrealized				Fair			Unrealized			Fair
		Losses (1)			Value				Losses (1)				Value			Losses (1)			Value
	31-Dec-13
	Fixed maturity investments
	U.S. government and agencies securities	$	(7,359	)	$	382,593			$	(260	)		$	6,050		$	(7,619	)	$	388,643
	U.S. state and municipal securities	(395		)	20,452				—				—			(395		)	20,452
	Foreign government securities	(1,981		)	139,503				(25		)		5,261			(2,006		)	144,764
	Government guaranteed corporate securities	(50		)	13,326				—				—			(50		)	13,326
	Corporate securities	(5,959		)	478,287				(552		)		28,690			(6,511		)	506,977
	Residential mortgage-backed securities	(17,542		)	514,702				(4,357		)		102,446			(21,899		)	617,148
	Commercial mortgage-backed securities	(7,681		)	384,548				(328		)		16,804			(8,009		)	401,352
	Collateralized loan and debt obligations	(48		)	20,733				(152		)		2,379			(200		)	23,112
	Asset-backed securities	(703		)	157,172				(152		)		7,011			(855		)	164,183
	Total fixed maturity investments	$	(41,718	)	$	2,111,316			$	(5,826	)		$	168,641		$	(47,544	)	$	2,279,957
	Short-term investments	(2		)	2,468				—				—			(2		)	2,468
	Total fixed income investments	$	(41,720	)	$	2,113,784			$	(5,826	)		$	168,641		$	(47,546	)	$	2,282,425
	Equity securities
	Equity investments	$	(1,995	)	$	36,751			$	—			$	—		$	(1,995	)	$	36,751
	Preferred equity investments	(79		)	2,987				—				—			(79		)	2,987
	Total equity securities	$	(2,074	)	$	39,738			$	—			$	—		$	(2,074	)	$	39,738
	-1	Gross unrealized losses include unrealized losses on non-OTTI and non-credit OTTI securities recognized in accumulated other comprehensive income at December 31, 2013.
Analysis Of OTTI	'
		Three Months Ended September 30,							Nine Months Ended September 30,
		2014			2013				2014				2013
	Total other-than-temporary impairment losses	$	(102	)	$	(190	)		$	(411	)		$	(1,575	)
	Portion of loss recognized in other comprehensive (loss) income	—			—				—				—
	Net impairment losses recognized in earnings	$	(102	)	$	(190	)		$	(411	)		$	(1,575	)
Credit Losses Recognized For Available For Sale Investments In Earnings, OTTI Loss Was Recognized In Accumulated Other Comprehensive Income	'
		Three Months Ended September 30,							Nine Months Ended September 30,
		2014			2013				2014				2013
	Beginning balance	$	(1,441	)	$	(1,769	)		$	(1,553	)		$	(2,000	)
	Addition for the amount related to the credit loss for which an other-than-temporary impairment was not previously recognized	—			—				—				—
	Addition for the amount related to the credit loss for which an other-than-temporary impairment was previously recognized	—			—				—				—
	Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security	—			—				—				—
	Reductions for securities sold during the period	579			113				691				344
	Ending balance	$	(862	)	$	(1,656	)		$	(862	)		$	(1,656	)

Fair_Value_Measurement_Tables

Fair Value Measurement (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Schedule Of Available For Sale Investments, Other Investments, Derivative Instruments And Debt Measured On A Recurring Basis	'
		Fair Value Measurements at December 31, 2013
		Total at			Quoted			Significant			Significant
		December 31, 2013			Prices in			Other			Unobservable
					Active			Observable			Inputs
					Markets for			Inputs			(Level 3)
					Identical			(Level 2)
					Assets
					(Level 1)
	Assets
	Fixed maturity investments
	U.S. government and agencies securities	$	769,343		$	20,248		$	749,095		$	—
	U.S. state and municipal securities	26,854			—			26,854			—
	Foreign government securities	182,647			—			182,647			—
	Government guaranteed corporate securities	35,145			—			35,145			—
	Corporate securities	1,227,299			—			1,226,553			746
	Residential mortgage-backed securities	1,187,191			—			1,186,943			248
	Commercial mortgage-backed securities	947,677			—			946,794			883
	Collateralized loan and debt obligations	94,552			—			92,095			2,457
	Asset-backed securities	353,256			—			350,262			2,994
	Total fixed maturity investments	$	4,823,964		$	20,248		$	4,796,388		$	7,328
	Equity securities
	Equity investments	174,669			117,776			56,893			—
	Emerging market debt funds	60,844			—			60,844			—
	Preferred equity investments	8,223			—			8,223			—
	Short-term fixed income fund	8,730			8,730			—			—
	Total equity securities	$	252,466		$	126,506		$	125,960		$	—
	Short-term investments	35,028			—			35,028			—
	Other investments	617,478			—			—			617,478
	Other assets (see Note 7)	108,272			—			94,234			14,038
	Total assets	$	5,837,208		$	146,754		$	5,051,610		$	638,844
	Liabilities
	Other liabilities (see Note 7)	$	49,452		$	—		$	29,883		$	19,569
	Debt	575,115			—			575,115			—
	Total liabilities	$	624,567		$	—		$	604,998		$	19,569
		Fair Value Measurements at September 30, 2014
		Total at			Quoted			Significant			Significant
		September 30, 2014			Prices in			Other			Unobservable
					Active			Observable			Inputs
					Markets for			Inputs			(Level 3)
					Identical			(Level 2)
					Assets
					(Level 1)
	Assets
	Fixed maturity investments
	U.S. government and agencies securities	$	514,672		$	—		$	514,672		$	—
	U.S. state and municipal securities	31,487			—			31,487			—
	Foreign government securities	205,693			—			205,693			—
	Government guaranteed corporate securities	46,201			—			46,201			—
	Corporate securities	1,280,366			—			1,279,666			700
	Residential mortgage-backed securities	1,203,322			—			1,203,294			28
	Commercial mortgage-backed securities	965,696			—			962,868			2,828
	Collateralized loan and debt obligations	207,214			—			206,574			640
	Asset-backed securities	416,769			—			413,772			2,997
	Total fixed maturity investments	$	4,871,420		$	—		$	4,864,227		$	7,193
	Equity securities
	Equity investments	182,514			123,283			59,231			—
	Emerging market debt funds	61,862			—			61,862			—
	Preferred equity investments	14,317			—			14,317			—
	Short-term fixed income fund	9,035			9,035			—			—
	Total equity securities	$	267,728		$	132,318		$	135,410		$	—
	Short-term investments	11,844			—			11,844			—
	Other investments	658,678			—			—			658,678
	Other assets (see Note 7)	147,488			—			132,666			14,822
Total assets	$	5,957,158		$	132,318		$	5,144,147		$	680,693
Liabilities
Other liabilities (see Note 7)	$	95,704		$	—		$	79,788		$	15,916
Debt	615,568			—			615,568			—
Total liabilities	$	711,272		$	—		$	695,356		$	15,916
Fair Value Inputs Assets And Liabilities Quantitative Information [Table Text Block]	'
		30-Sep-14
		Fair Value			Valuation		Unobservable	Low			High			Weighted Average
		(Level 3)			Techniques		Inputs							or Actual
		(U.S. dollars in thousands, except for correlation and commodity curve)
	Net weather and energy related derivative liabilities	$	(1,094	)	Historical		Correlation	0			1			Actual
					Analysis and Simulation
							Weather curve	$	400		$	2,500		Actual
							Commodity curve	$	28.5		$	122.2		Actual
Reconciliation Of The Beginning And Ending Balances For All Available For Sale Investments, Other Investments And Derivative Instruments Measured At Fair Value On A Recurring Basis Using Level 3 Inputs	'
		Three Months Ended September 30, 2014
		Fixed maturity			Other			Other assets			Total assets			Other
		investments			investments									liabilities
	Level 3, beginning of period	$	9,515		$	648,642		$	10,992		$	669,149		$	(10,284	)
	Total equity income and realized gains included in earnings	9			10,913			—			10,922			—
	Total equity losses and losses included in earnings	(6		)	(12,698		)	—			(12,704		)	—
	Total income included in other underwriting income (loss)	—			—			3,180			3,180			4,794
	Total loss included in other underwriting income (loss)	—			—			(5,235		)	(5,235		)	(3,719		)
	Change in unrealized gains included in other comprehensive (loss) income	245			—			—			245			—
	Change in unrealized losses included in other comprehensive (loss) income	(104		)	—			—			(104		)	—
	Purchases	842			26,190			1,501			28,533			(751		)
	Issues	—			—			7,331			7,331			(10,917		)
	Sales	(545		)	(14,369		)	—			(14,914		)	—
	Settlements	—			—			(2,947		)	(2,947		)	4,961
	Transfers into Level 3	2,198			—			—			2,198			—
	Transfers out of Level 3	(4,961		)	—			—			(4,961		)	—
	Level 3, end of period	$	7,193		$	658,678		$	14,822		$	680,693		$	(15,916	)
		Three Months Ended September 30, 2013
		Fixed maturity			Other			Other assets			Total assets			Other
		investments			investments									liabilities
	Level 3, beginning of period	$	7,546		$	569,393		$	—		$	576,939		$	—
	Total equity income and realized gains included in earnings	56			19,108			—			19,164			—
	Total equity losses and losses included in earnings	(15		)	(5,864		)	—			(5,879		)	—
	Total income included in other underwriting income (loss)	—			—			—			—			—
	Total loss included in other underwriting income (loss)	—			—			—			—			—
	Change in unrealized gains included in other comprehensive (loss) income	111			—			—			111			—
	Change in unrealized losses included in other comprehensive (loss) income	(62		)	—			—			(62		)	—
	Purchases	—			16,597			—			16,597			—
	Sales	(1,879		)	(5,078		)	—			(6,957		)	—
	Transfers in to Level 3	7,903			—			—			7,903			—
	Transfers out of Level 3	(1,202		)	—			—			(1,202		)	—
	Level 3, end of period	$	12,458		$	594,156		$	—		$	606,614		$	—
		Nine Months Ended September 30, 2014
		Fixed maturity			Other			Other assets			Total assets			Other
		investments			investments									liabilities
	Level 3, beginning of period	$	7,328		$	617,478		$	14,038		$	638,844		$	(19,569	)
	Total equity income and realized gains included in earnings	62			46,385			—			46,447			—
	Total equity losses and losses included in earnings	(32		)	(23,844		)	—			(23,876		)	—
	Total income included in other underwriting income (loss)	—			—			18,396			18,396			24,842
	Total loss included in other underwriting income (loss)	—			—			(23,845		)	(23,845		)	(20,672		)
	Change in unrealized gains included in other comprehensive (loss) income	445			—			—			445			—
	Change in unrealized losses included in other comprehensive (loss) income	(255		)	—			—			(255		)	—
	Purchases	842			52,731			1,501			55,074			(751		)
	Issues	—			—			10,912			10,912			(18,080		)
	Sales	(1,585		)	(34,072		)	—			(35,657		)	—
	Settlements	—			—			(6,180		)	(6,180		)	18,314
	Transfers in to Level 3	7,201			—			—			7,201			—
	Transfers out of Level 3	(6,813		)	—			—			(6,813		)	—
	Level 3, end of period	$	7,193		$	658,678		$	14,822		$	680,693		$	(15,916	)
		Nine Months Ended September 30, 2013
		Fixed maturity			Other			Other assets			Total assets			Other
		investments			investments									liabilities
	Level 3, beginning of period	$	8,497		$	517,546		$	882		$	526,925		$	(1,922	)
	Total equity income and realized gains included in earnings	104			61,010			—			61,114			—
	Total equity losses and losses included in earnings	(17		)	(17,927		)	—			(17,944		)	—
	Total income included in other underwriting income (loss)	—			—			—			—			2,354
	Total loss included in other underwriting income (loss)	—			—			(1,182		)	(1,182		)	—
	Change in unrealized gains included in other comprehensive income (loss)	438			—			—			438			—
	Change in unrealized losses included in other comprehensive income (loss)	(270		)	—			—			(270		)	—
	Purchases	—			62,011			—			62,011			—
	Issues	—			—			300			300			(432		)
	Sales	(6,081		)	(28,484		)	—			(34,565		)	—
	Transfers in to Level 3	11,550			—			—			11,550			—
Transfers out of Level 3	(1,763		)	—			—			(1,763		)	—
Level 3, end of period	$	12,458		$	594,156		$	—		$	606,614		$	—

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Schedule Of Computation Of Basic And Diluted Earnings Per Share	'
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Numerator:
	Net income available to common and participating common shareholders	$	68,046		$	75,228		$	239,313		$	220,170
	Less amount allocated to participating common	(1,930		)	(1,997		)	(6,907		)	(4,742		)
	shareholders(1)
	Net income allocated to common shareholders	$	66,116		$	73,231		$	232,406		$	215,428
	Denominator:
	Weighted average shares - basic	43,464,790			43,099,841			43,332,461			42,719,837
	Share equivalents:
	Options	45,625			—			23,237			—
	Restricted share units	—			298			94			594
	Weighted average shares - diluted	43,510,415			43,100,139			43,355,792			42,720,431
	Basic earnings per common share	$	1.52		$	1.7		$	5.36		$	5.04
	Diluted earnings per common share	$	1.52		$	1.7		$	5.36		$	5.04
	-1	Represents earnings attributable to holders of unvested restricted shares issued under the Company's equity compensation plan that are considered participating. In periods of loss, no losses are allocated to participating common shareholders (unvested restricted shares).
Schedule Of Dividends Declared	'
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Dividends declared per Series A preferred share	$	0.484375		$	0.484375		$	1.453125		$	1.453125
	Dividends declared per Series B preferred share	$	0.46875		$	0.46875		$	1.40625		$	1.40625
	Dividends declared per common share	$	0.34		$	0.32		$	1.02		$	0.96

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]	'
Schedule Of Accumulated Other Comprehensive Income	'
		For the Nine Months Ended September 30, 2013
		Losses on cash flow hedges				Unrealized gains (losses) on available for sale securities			Foreign currency translation adjustments			Total
	Beginning balance	$	(1,944	)		$	141,731		$	12,676		$	152,463
	Other comprehensive (loss) income before reclassifications	—				(74,001		)	(1,057		)	(75,058		)
	Amounts reclassified from accumulated other comprehensive income (1)	67				(8,015		)	—			(7,948		)
	Net current period other comprehensive (loss) income	67				(82,016		)	(1,057		)	(83,006		)
	Ending balance	$	(1,877	)		$	59,715		$	11,619		$	69,457
	(1)All amounts are net of tax.
		For the Three Months Ended September 30, 2013
		Losses on cash flow hedges				Unrealized gains on available for sale securities			Foreign currency translation adjustments			Total
	Beginning balance	$	(1,899	)		30,636			$	2,701		$	31,438
	Other comprehensive (loss) income before reclassifications	—				22,358			8,918			31,276
	Amounts reclassified from accumulated other comprehensive income (1)	22				6,721			—			6,743
	Net current period other comprehensive (loss) income	22				29,079			8,918			38,019
	Ending balance	$	(1,877	)		$	59,715		$	11,619		$	69,457
	(1)All amounts are net of tax.
		For the Three Months Ended September 30, 2014
		Losses on				Unrealized gains (losses) on available for sale securities			Foreign currency translation adjustments			Total
		cash flow hedges
	Beginning balance	$	(1,810	)		$	106,989		$	30,859		$	136,038
	Other comprehensive (loss) income before reclassifications	—				(25,100		)	(20,404		)	(45,504		)
	Amounts reclassified from accumulated other comprehensive income (1)	22				(9,257		)	—			(9,235		)
	Net current period other comprehensive (loss) income	22				(34,357		)	(20,404		)	(54,739		)
	Ending balance	$	(1,788	)		$	72,632		$	10,455		$	81,299
	(1)All amounts are net of tax.
		For the Three Months Ended September 30, 2013
		Losses on cash flow hedges				Unrealized gains on available for sale securities			Foreign currency translation adjustments			Total
	Beginning balance	$	(1,899	)		30,636			$	2,701		$	31,438
	Other comprehensive (loss) income before reclassifications	—				22,358			8,918			31,276
	Amounts reclassified from accumulated other comprehensive income (1)	22				6,721			—			6,743
	Net current period other comprehensive (loss) income	22				29,079			8,918			38,019
	Ending balance	$	(1,877	)		$	59,715		$	11,619		$	69,457
		For the Nine Months Ended September 30, 2014
		Losses on cash flow hedges				Unrealized gains (losses) on available for sale securities			Foreign currency translation adjustments			Total
	Beginning balance	$	(1,855	)		$	45,950		$	18,636		$	62,731
	Other comprehensive (loss) income before reclassifications	—				41,895			(8,181		)	33,714
	Amounts reclassified from accumulated other comprehensive income (1)	67				(15,213		)	—			(15,146		)
	Net current period other comprehensive (loss) income	67				26,682			(8,181		)	18,568
	Ending balance	$	(1,788	)		$	72,632		$	10,455		$	81,299
	(1)All amounts are net of tax.
Reclassification Out Of Accumulated Other Comprehensive Income	'
	Nine Months Ended September 30, 2014
	Details about accumulated other comprehensive		Amount reclassified				Affected line item in the Unaudited
	income components		from accumulated other				Condensed Consolidated Statements of
			comprehensive income				Income and Comprehensive Income
	Losses on cash flow hedges - Debt		$	67			Interest expense
			67				Total before income taxes
			—				Income tax expense
			$	67			Total net of income taxes
	Unrealized (gains) losses on available for sale securities		$	(15,539	)		Net realized and unrealized investment gains
			411				Net impairment losses recognized in earnings
			(15,128		)		Total before income taxes
			(85		)		Income tax benefit
			$	(15,213	)		Total net of income taxes
	Nine Months Ended September 30, 2013
	Details about accumulated other comprehensive		Amount reclassified				Affected line item in the Unaudited
	income components		from accumulated other				Condensed Consolidated Statements of
			comprehensive income				Income and Comprehensive Income
	Losses on cash flow hedges - Debt		$	67			Interest expense
			67				Total before income taxes
			—				Income tax expense
			$	67			Total net of income taxes
	Unrealized (gains) losses on available for sale securities		$	(10,267	)		Net realized and unrealized investment gains
			1,575				Net impairment losses recognized in earnings
			(8,692		)		Total before income taxes
			677				Income tax expense
			$	(8,015	)		Total net of income taxes
	Three Months Ended September 30, 2014
	Details about accumulated other comprehensive		Amount reclassified				Affected line item in the Unaudited
	income components		from accumulated other				Condensed Consolidated Statements of
			comprehensive income				Income and Comprehensive Income
	Losses on cash flow hedges - Debt		$	22			Interest expense
			22				Total before income taxes
			—				Income tax expense
			$	22			Total net of income taxes
	Unrealized (gains) losses on available for sale securities		$	(9,208	)		Net realized and unrealized investment gains
			102				Net impairment losses recognized in earnings
			(9,106		)		Total before income taxes
			195				Income tax expense
			$	(8,911	)		Total net of income taxes
	Three Months Ended September 30, 2013
	Details about accumulated other comprehensive		Amount reclassified				Affected line item in the Unaudited
	income components		from accumulated other				Condensed Consolidated Statements of
			comprehensive income				Income and Comprehensive Income
	Losses on cash flow hedges - Debt		$	22			Interest expense
			22				Total before income taxes
			—				Income tax expense
			$	22			Total net of income taxes
	Unrealized losses on available for sale securities		$	6,999			Net realized and unrealized investment losses
			190				Net impairment losses recognized in earnings
			7,189				Total before income taxes
			(468		)		Income tax benefit
			$	6,721			Total net of income taxes

Derivatives_Tables

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Schedule Of The Fair Value And Related Notional Amounts Of Derivatives Included In The Company's Consolidated Balance Sheet	'
		30-Sep-14						31-Dec-13
		Fair			Notional			Fair			Notional
		Value			Principal			Value			Principal
					Amount						Amount
	Derivatives recorded in other assets
	Foreign exchange forward contracts	$	1,128		$	40,923		$	251		$	19,269
	Credit default swaps	11			1,785			—			—
	Interest rate swaps	211			72,700			124			16,100
	Interest rate swaptions	—			—			39			24,338
	TBAs	131,316			127,255			93,820			93,840
	Energy and weather contracts	14,822			79,846			14,038			53,986
	Total recorded in other assets	$	147,488					$	108,272
	Derivatives recorded in other liabilities
	Foreign exchange forward contracts	$	312		$	23,641		$	172		$	15,861
	Interest rate swaps	731			11,782			933			12,193
	Interest rate swaptions	18			56,216			543			361,455
	Interest rate futures	—			—			17			103,935
	TBAs	78,727			76,000			28,218			28,000
	Energy and weather contracts	15,916			115,574			19,569			66,113
	Total recorded in other liabilities	$	95,704					$	49,452
	Net derivative asset	$	51,784					$	58,820
Schedule Of The Gains And Losses On The Consolidated Statements Of Income And Comprehensive Income From Derivatives	'
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Total included in net foreign exchange losses from foreign exchange forward contracts	$	1,214		$	(123	)	$	815		$	207
	Futures contracts	$	—		$	112		$	136		$	64
	Credit default swaps	6			(68		)	20			49
	Interest rate swaps	384			(67		)	(698		)	(228		)
	Interest rate swaptions	(3		)	392			425			291
	TBAs	193			(11		)	2,649			(476		)
	Total included in net realized and unrealized investment gains (losses)	$	580		$	358		$	2,532		$	(300	)
	Total included in other underwriting income (loss) from energy and weather contracts	$	1,784		$	—		$	1,486		$	1,172
	Total gains from derivatives	$	3,578		$	235		$	4,833		$	1,079

Segment_Reporting_Tables

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Summary Of The Segment Revenues, Results And Reserve For Losses And Loss Expenses	'
		Three Months Ended September 30, 2013
		Insurance			Reinsurance			Total
	Revenues
	Gross premiums written	$	344,819		$	199,544		$	544,363
	Ceded premiums written	(120,481		)	(28,549		)	(149,030		)
	Net premiums written	224,338			170,995			395,333
	Net premiums earned	291,477			262,068			553,545
	Other underwriting loss	—			(943		)	(943		)
		291,477			261,125			552,602
	Expenses
	Net losses and loss expenses	228,409			110,627			339,036
	Acquisition expenses	18,440			60,335			78,775
	General and administrative expenses	35,641			31,829			67,470
		282,490			202,791			485,281
	Underwriting income	$	8,987		$	58,334		$	67,321
	Net loss ratio	78.4		%	42.3		%	61.3		%
	Acquisition expense ratio	6.3		%	23		%	14.2		%
	General and administrative expense ratio	12.2		%	12.1		%	12.2		%
	Combined ratio	96.9		%	77.4		%	87.7		%
	Reserve for losses and loss expenses	$	2,146,136		$	1,905,966		$	4,052,102
		Nine Months Ended September 30, 2014
		Insurance			Reinsurance			Total
	Revenues
	Gross premiums written	$	1,394,145		$	1,078,905		$	2,473,050
	Ceded premiums written	(674,441		)	(98,371		)	(772,812		)
	Net premiums written	719,704			980,534			1,700,238
	Net premiums earned	616,167			776,532			1,392,699
	Other underwriting loss	—			(3,939		)	(3,939		)
		616,167			772,593			1,388,760
	Expenses
	Net losses and loss expenses	434,777			291,584			726,361
	Acquisition expenses	47,559			196,591			244,150
	General and administrative expenses	133,930			106,646			240,576
		616,266			594,821			1,211,087
	Underwriting (loss) income	$	(99	)	$	177,772		$	177,673
	Net loss ratio	70.6		%	37.6		%	52.2		%
	Acquisition expense ratio	7.7		%	25.3		%	17.5		%
	General and administrative expense ratio	21.7		%	13.7		%	17.3		%
	Combined ratio	100		%	76.6		%	87		%
		Three Months Ended September 30, 2014
		Insurance			Reinsurance			Total
	Revenues
	Gross premiums written	$	420,343		$	205,767		$	626,110
	Ceded premiums written	(222,704		)	(13,300		)	(236,004		)
	Net premiums written	197,639			192,467			390,106
	Net premiums earned	253,583			261,312			514,895
	Other underwriting income	—			2,123			2,123
		253,583			263,435			517,018
	Expenses
	Net losses and loss expenses	196,677			93,592			290,269
	Acquisition expenses	20,170			73,222			93,392
	General and administrative expenses	44,957			35,958			80,915
		261,804			202,772			464,576
	Underwriting (loss) income	$	(8,221	)	$	60,663		$	52,442
	Net loss ratio	77.5		%	35.8		%	56.4		%
	Acquisition expense ratio	8		%	28		%	18.1		%
	General and administrative expense ratio	17.7		%	13.8		%	15.7		%
	Combined ratio	103.2		%	77.6		%	90.2		%
	Reserve for losses and loss expenses	$	2,134,985		$	1,762,498		$	3,897,483
		Nine Months Ended September 30, 2013
		Insurance			Reinsurance			Total
	Revenues
	Gross premiums written	$	1,274,703		$	1,019,732		$	2,294,435
Ceded premiums written	(454,169		)	(71,397		)	(525,566		)
Net premiums written	820,534			948,335			1,768,869
Net premiums earned	710,507			806,490			1,516,997
Other underwriting income	—			694			694
	710,507			807,184			1,517,691
Expenses
Net losses and loss expenses	543,717			373,347			917,064
Acquisition expenses	48,024			174,255			222,279
General and administrative expenses	114,792			100,515			215,307
	706,533			648,117			1,354,650
Underwriting income	$	3,974		$	159,067		$	163,041
Net loss ratio	76.4		%	46.3		%	60.4		%
Acquisition expense ratio	6.8		%	21.6		%	14.7		%
General and administrative expense ratio	16.2		%	12.5		%	14.2		%
Combined ratio	99.4		%	80.4		%	89.3		%
Schedule Of Segment Results To Income Before Income Taxes	'
		Nine Months Ended September 30,
		2014			2013
	Total underwriting income	$	177,673		$	163,041
	Net investment income	105,649			119,870
	Net foreign exchange losses	(4,066		)	(8,496		)
	Net realized and unrealized investment gains	18,071			9,967
	Net impairment losses recognized in earnings	(411		)	(1,575		)
	Amortization of intangibles	(4,863		)	(5,378		)
	Interest expense	(31,910		)	(27,138		)
	Income before income taxes	$	260,143		$	250,291
		Three Months Ended September 30,
		2014			2013
	Total underwriting income	$	52,442		$	67,321
	Net investment income	25,357			38,097
	Net foreign exchange losses	(783		)	(2,201		)
	Net realized and unrealized investment gains (losses)	9,788			(6,640		)
	Net impairment losses recognized in earnings	(102		)	(190		)
	Amortization of intangibles	(1,623		)	(1,652		)
	Interest expense	(13,127		)	(9,048		)
	Income before income taxes	$	71,952		$	85,687
Schedule Of Gross And Net Premiums By Line Of Business	'
		Gross			Net			Gross			Net
		premiums			premiums			premiums			premiums
		written			written			written			written
	Business Segment	2014			2014			2013			2013
	Insurance
	Agriculture	$	796,445		$	431,007		$	896,169		$	546,284
	Casualty and other specialty	366,329			189,876			239,943			179,065
	Professional lines	176,061			64,632			93,481			62,963
	Property	55,310			34,189			45,110			32,222
	Total Insurance	1,394,145			719,704			1,274,703			820,534
	Reinsurance
	Catastrophe	332,193			243,531			341,973			281,990
	Property	283,107			283,015			288,448			283,455
	Casualty	139,266			137,669			211,458			210,030
	Professional lines	131,256			131,256			50,505			50,505
	Specialty	193,083			185,063			127,348			122,355
	Total Reinsurance	1,078,905			980,534			1,019,732			948,335
	Total	$	2,473,050		$	1,700,238		$	2,294,435		$	1,768,869
		Gross			Net			Gross			Net
		premiums			premiums			premiums			premiums
		written			written			written			written
	Business Segment	2014			2014			2013			2013
	Insurance
	Agriculture	$	188,011		$	103,536		$	200,062		$	120,617
	Casualty and other specialty	144,706			58,390			95,862			72,431
	Professional lines	62,631			20,216			34,221			20,972
	Property	24,995			15,497			14,674			10,318
	Total Insurance	420,343			197,639			344,819			224,338
	Reinsurance
	Catastrophe	47,173			41,157			38,676			12,551
	Property	73,807			73,807			91,653			90,528
	Casualty	23,409			23,409			27,649			27,648
	Professional lines	21,520			21,520			25,670			25,670
	Specialty	39,858			32,574			15,896			14,598
	Total Reinsurance	205,767			192,467			199,544			170,995
	Total	$	626,110		$	390,106		$	544,363		$	395,333

Commitments_And_Contingencies_

Commitments And Contingencies (Tables)	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Schedule Of Percentage Of Net Premiums	'
	Broker	2014		2013
	Marsh & McLennan Companies, Inc.	20.9	%	15	%
	Aon Benfield	15.4	%	18.5	%
	Willis Companies	14.2	%	12.4	%
	Total of largest brokers	50.5	%	45.9	%
Schedule Of Future Minimum Lease Commitments	'
	Twelve months ended September 30,	Amount
	2015	$	16,066
	2016	13,527
	2017	11,957
	2018	11,465
	2019	10,809
	2020 and thereafter	36,377
		$	100,201

Investments_Narrative_Details

Investments (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Investments [Abstract]	'	'	'	'	'
Number of available for sale securities in an unrealized loss position	752	'	752	'	880
Number of securities in a continuous unrealized loss position for twelve months or greater	222	'	222	'	71
Unrealized losses	($19,100,000)	'	($19,100,000)	'	($49,600,000)	[1]
Unrealized losses, 12 months or greater	-11,100,000	'	-11,100,000	'	-5,800,000	[1]
OTTI losses recognized	$102,000	$190,000	$411,000	$1,575,000	'
[1]	Gross unrealized losses include unrealized losses on non-OTTI and non-credit OTTI securities recognized in accumulated other comprehensive income at DecemberB 31, 2013.

Investments_Composition_Of_Net

Investments (Composition 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
Investments [Abstract]	'	'	'	'
Available for sale investments	$29,959	$27,889	$91,905	$86,036
Other investments	-1,785	13,244	22,542	43,083
Cash and cash equivalents	581	752	1,878	2,043
Investment income	28,755	41,885	116,325	131,162
Investment expenses	-3,398	-3,788	-10,676	-11,292
Net investment income	$25,357	$38,097	$105,649	$119,870

Investments_Summary_Of_Investm

Investments (Summary Of Investment Portfolio By Type) (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Investment Holdings [Line Items]	'		'
Investments, Fair Value Disclosure	$6,462,047		$6,500,650
Percentage of Investment	100.00%		100.00%
Fixed Maturities [Member]	'		'
Investment Holdings [Line Items]	'		'
Investments, Fair Value Disclosure	4,871,420		4,823,964
Percentage of Investment	75.40%		74.20%
Cash and Cash Equivalents [Member]	'		'
Investment Holdings [Line Items]	'		'
Investments, Fair Value Disclosure	652,377	[1]	771,714	[1]
Percentage of Investment	10.10%	[1]	11.90%	[1]
Other Investments [Member]	'		'
Investment Holdings [Line Items]	'		'
Investments, Fair Value Disclosure	658,678	[2]	617,478	[2]
Percentage of Investment	10.20%	[2]	9.50%	[2]
Short-term Investments [Member]	'		'
Investment Holdings [Line Items]	'		'
Investments, Fair Value Disclosure	11,844		35,028
Percentage of Investment	0.20%		0.50%
Equity Securities [Member]	'		'
Investment Holdings [Line Items]	'		'
Investments, Fair Value Disclosure	$267,728		$252,466
Percentage of Investment	4.10%		3.90%
[1]	Includes net receivable on sales of investments and net payable on purchases of investments.
[2]	Consists of investments in alternative funds and specialty funds.

Investments_Composition_Of_The

Investments (Composition Of The Fixed Income Portfolio By Investment Ratings Assigned By Rating Agencies) (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
US Government and Agencies Securities [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	$514,672	[1]	$769,343	[1]
Percentage of fixed income portfolio by investment ratings	10.50%	[1]	15.80%	[1]
Standard & Poor's, AAA Rating [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	1,153,558	[1]	972,820	[1]
Percentage of fixed income portfolio by investment ratings	23.70%	[1]	20.00%	[1]
Standard & Poor's, AA Rating [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	1,738,964	[1]	1,771,156	[1]
Percentage of fixed income portfolio by investment ratings	35.70%	[1]	36.50%	[1]
Standard & Poor's, A Rating [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	952,894	[1]	895,549	[1]
Percentage of fixed income portfolio by investment ratings	19.50%	[1]	18.40%	[1]
Standard & Poor's, BBB Rating [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	407,093	[1]	363,722	[1]
Percentage of fixed income portfolio by investment ratings	8.30%	[1]	7.50%	[1]
Standard & Poor's, Below BBB Rating [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	94,824	[1]	66,791	[1]
Percentage of fixed income portfolio by investment ratings	1.90%	[1]	1.40%	[1]
Not Rated [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	21,259	[1]	19,611	[1]
Percentage of fixed income portfolio by investment ratings	0.40%	[1]	0.40%	[1]
Fixed Income Investments [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	$4,883,264	[1]	$4,858,992	[1]
Percentage of fixed income portfolio by investment ratings	100.00%	[1]	100.00%	[1]
[1]	The credit rating for each security reflected above was determined based on the rating assigned to the individual security by StandardB & Poor's Financial Services LLC ("StandardB & Poor's"). If a rating is not supplied by StandardB & Poor's, the equivalent rating supplied by Moody's Investors Service, Inc. ("Moody's"), Fitch Ratings, Inc., or DBRS, Inc. is used.

Investments_Contractual_Maturi

Investments (Contractual Maturities Of Fixed Income Securities) (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'		'
Due within one year, amortized cost	$128,535		$144,814
Due within one year, fair value	129,382		145,653
Due after one year through five years, amortized cost	1,575,875		1,808,001
Due after one year through five years, fair value	1,583,414		1,815,240
Due after five years through ten years, amortized cost	339,764		290,391
Due after five years through ten years, fair value	341,993		288,486
Due after ten years, amortized cost	33,034		26,344
Due after ten years, fair value	35,474		26,937
Fixed income investments, amortized cost	4,820,169		4,802,580
Fixed income investments, fair value	4,871,420		4,823,964
Residential Mortgage Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
No single maturity date, amortized cost	1,185,911		1,192,085
No single maturity date, fair value	1,203,322		1,187,191
Fixed income investments, amortized cost	1,185,911		1,192,085
Fixed income investments, fair value	1,203,322		1,187,191
Commercial Mortgage Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
No single maturity date, amortized cost	948,460		932,263
No single maturity date, fair value	965,696		947,677
Fixed income investments, amortized cost	948,460		932,263
Fixed income investments, fair value	965,696		947,677
Collateralized Loan and Debt Obligations [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
No single maturity date, amortized cost	205,465		92,519
No single maturity date, fair value	207,214		94,552
Fixed income investments, amortized cost	205,465	[1]	92,519	[2]
Fixed income investments, fair value	207,214	[1]	94,552	[2]
Asset-backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
No single maturity date, amortized cost	414,968		351,192
No single maturity date, fair value	416,769		353,256
Fixed income investments, amortized cost	414,968		351,192
Fixed income investments, fair value	416,769		353,256
Fixed Income Investments [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	4,832,012		4,837,609
Fixed income investments, fair value	$4,883,264		$4,858,992
[1]	Balances include amounts related to collateralized debt obligations held with total fair values of $10.7 million.
[2]	Balances include amounts related to collateralized debt obligations held with total fair values of $18.7 million.

Investments_Other_Investments_

Investments (Other Investments) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Equity Method Investments [Line Items]	'	'
Other investments, market value	$658,678	$617,478
Commitments under investment fund classified within other investments	64,473	57,997
Prohibited amount under redemption requests over the next 12 months	107,333	107,109
Alternative Funds [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Other investments, market value	499,711	461,141
Commitments under investment fund classified within other investments	64,473	57,997
Prohibited amount under redemption requests over the next 12 months	107,333	107,109
Hedge Funds [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Other investments, market value	431,278	401,438
Commitments under investment fund classified within other investments	0	0
Prohibited amount under redemption requests over the next 12 months	38,900	47,406
Private Equity Funds [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Other investments, market value	68,433	59,703
Commitments under investment fund classified within other investments	64,473	57,997
Prohibited amount under redemption requests over the next 12 months	68,433	59,703
Specialty Funds [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Other investments, market value	158,967	156,337
Commitments under investment fund classified within other investments	0	0
Prohibited amount under redemption requests over the next 12 months	0	0
High Yield Loan Funds [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Other investments, market value	112,892	111,254
Commitments under investment fund classified within other investments	0	0
Prohibited amount under redemption requests over the next 12 months	0	0
Convertible Debt Funds [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Other investments, market value	46,075	45,083
Commitments under investment fund classified within other investments	0	0
Prohibited amount under redemption requests over the next 12 months	$0	$0

Investments_Other_Investments_1

Investments (Other Investments Narrative) (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]	'	'
Other investments, invested amount	$462,100,000	$440,900,000
Other investments, market value	658,678,000	617,478,000
Alternative Funds [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Other investments, market value	499,711,000	461,141,000
Hedge Funds [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Estimated liquidation, percentage in next 12 months	91.00%	'
Other investments, market value	431,278,000	401,438,000
Hedge Funds [Member] | Maximum [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Estimated notice period, in days	'90 days	'
Hedge Funds [Member] | Minimum [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Estimated notice period, in days	'30 days	'
Private Equity Funds [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Other investments, market value	68,433,000	59,703,000
Private Equity Funds [Member] | Maximum [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Estimated remaining liquidation period in years	'10 years	'
Private Equity Funds [Member] | Minimum [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Estimated remaining liquidation period in years	'5 years	'
Specialty Funds [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Other investments, market value	158,967,000	156,337,000
High Yield Loan Funds [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Other investments, market value	112,892,000	111,254,000
High Yield Loan Funds [Member] | Maximum [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Estimated notice period, in days	'90 days	'
High Yield Loan Funds [Member] | Minimum [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Estimated notice period, in days	'30 days	'
Convertible Debt Funds [Member]	'	'
Schedule of Equity Method Investments [Line Items]	'	'
Estimated notice period, in days	'5 days	'
Other investments, market value	$46,075,000	$45,083,000

Investments_Net_Realized_and_U

Investments (Net Realized and Unrealized Investment Gains (Losses)) (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
Investments [Abstract]	'		'		'		'
Gross realized gains on investment sales	$10,683		$6,180		$28,317		$30,191
Gross realized losses on investment sales	-1,475		-13,178		-12,778		-19,924
Change in fair value of derivative financial instruments	580	[1]	358	[1]	2,532	[1]	-300	[1]
Net realized and unrealized investment gains (losses)	$9,788		($6,640)		$18,071		$9,967
[1]	For additional information on the Companybs derivative financial instruments, see Note 7.

Investments_Amortized_Cost_Fai

Investments (Amortized Cost, Fair Value, Unrealized Gains And Losses And Non-Credit Other-Than-Temporary Impairments) (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	$4,820,169,000		$4,802,580,000
Fixed income investments, fair value	4,871,420,000		4,823,964,000
Equity securities, cost	239,487,000		227,828,000
Equity securities, fair value	267,728,000		252,466,000
Gross unrealized loss related to securities, non-credit OTTI	0		100,000
US Government and Agencies Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	512,199,000		771,227,000
Fixed income investments, gross unrealized gains	5,450,000		5,735,000
Fixed income investments, gross unrealized losses	-2,977,000		-7,619,000
Fixed income investments, fair value	514,672,000		769,343,000
Non-Credit OTTI	0	[1]	0	[2]
US State and Municipal Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	31,437,000		27,138,000
Fixed income investments, gross unrealized gains	207,000		111,000
Fixed income investments, gross unrealized losses	-157,000		-395,000
Fixed income investments, fair value	31,487,000		26,854,000
Non-Credit OTTI	0	[1]	0	[2]
Foreign Government Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	204,033,000		183,650,000
Fixed income investments, gross unrealized gains	2,033,000		1,003,000
Fixed income investments, gross unrealized losses	-373,000		-2,006,000
Fixed income investments, fair value	205,693,000		182,647,000
Non-Credit OTTI	0	[1]	0	[2]
Government Guaranteed Corporate Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	45,577,000		34,921,000
Fixed income investments, gross unrealized gains	624,000		274,000
Fixed income investments, gross unrealized losses	0		-50,000
Fixed income investments, fair value	46,201,000		35,145,000
Non-Credit OTTI	0	[1]	0	[2]
Corporate Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	1,272,119,000		1,217,585,000
Fixed income investments, gross unrealized gains	13,037,000		16,225,000
Fixed income investments, gross unrealized losses	-4,790,000		-6,511,000
Fixed income investments, fair value	1,280,366,000		1,227,299,000
Non-Credit OTTI	0	[1]	0	[2]
Residential Mortgage Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	1,185,911,000		1,192,085,000
Fixed income investments, gross unrealized gains	21,984,000		17,005,000
Fixed income investments, gross unrealized losses	-4,573,000		-21,899,000
Fixed income investments, fair value	1,203,322,000		1,187,191,000
Non-Credit OTTI	-3,319,000	[1]	-4,257,000	[2]
Commercial Mortgage Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	948,460,000		932,263,000
Fixed income investments, gross unrealized gains	20,763,000		23,423,000
Fixed income investments, gross unrealized losses	-3,527,000		-8,009,000
Fixed income investments, fair value	965,696,000		947,677,000
Non-Credit OTTI	-5,000	[1]	-47,000	[2]
Collateralized Loan and Debt Obligations [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	205,465,000	[3]	92,519,000	[4]
Fixed income investments, gross unrealized gains	1,974,000	[3]	2,233,000	[4]
Fixed income investments, gross unrealized losses	-225,000	[3]	-200,000	[4]
Fixed income investments, fair value	207,214,000	[3]	94,552,000	[4]
Non-Credit OTTI	0	[1],[3]	0	[2],[4]
Asset-backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	414,968,000		351,192,000
Fixed income investments, gross unrealized gains	2,333,000		2,919,000
Fixed income investments, gross unrealized losses	-532,000		-855,000
Fixed income investments, fair value	416,769,000		353,256,000
Non-Credit OTTI	0	[1]	-163,000	[2]
Fixed Maturities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	4,820,169,000		4,802,580,000
Fixed income investments, gross unrealized gains	68,405,000		68,928,000
Fixed income investments, gross unrealized losses	-17,154,000		-47,544,000
Fixed income investments, fair value	4,871,420,000		4,823,964,000
Non-Credit OTTI	-3,324,000	[1]	-4,467,000	[2]
Short-term Investments [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	11,843,000		35,029,000
Fixed income investments, gross unrealized gains	1,000		1,000
Fixed income investments, gross unrealized losses	0		-2,000
Fixed income investments, fair value	11,844,000		35,028,000
Non-Credit OTTI	0	[1]	0	[2]
Fixed Income Investments [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, amortized cost	4,832,012,000		4,837,609,000
Fixed income investments, gross unrealized gains	68,406,000		68,929,000
Fixed income investments, gross unrealized losses	-17,154,000		-47,546,000
Fixed income investments, fair value	4,883,264,000		4,858,992,000
Non-Credit OTTI	-3,324,000	[1]	-4,467,000	[2]
Equity Investments [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Equity securities, cost	157,924,000		152,525,000
Equity securities, gross unrealized gains	26,471,000		24,139,000
Equity securities, gross unrealized losses	-1,881,000		-1,995,000
Equity securities, fair value	182,514,000		174,669,000
Non-Credit OTTI	0	[1]	0	[2]
Emerging Market Debt Funds [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Equity securities, cost	60,250,000		60,250,000
Equity securities, gross unrealized gains	1,612,000		594,000
Equity securities, gross unrealized losses	0		0
Equity securities, fair value	61,862,000		60,844,000
Non-Credit OTTI	0	[1]	0	[2]
Preferred Equity Investments [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Equity securities, cost	12,283,000		6,325,000
Equity securities, gross unrealized gains	2,071,000		1,977,000
Equity securities, gross unrealized losses	-37,000		-79,000
Equity securities, fair value	14,317,000		8,223,000
Non-Credit OTTI	0	[1]	0	[2]
Short-term Fixed Income Fund [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Equity securities, cost	9,030,000		8,728,000
Equity securities, gross unrealized gains	6,000		2,000
Equity securities, gross unrealized losses	-1,000		0
Equity securities, fair value	9,035,000		8,730,000
Non-Credit OTTI	0	[1]	0	[2]
Equity Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Equity securities, cost	239,487,000		227,828,000
Equity securities, gross unrealized gains	30,160,000		26,712,000
Equity securities, gross unrealized losses	-1,919,000		-2,074,000
Equity securities, fair value	267,728,000		252,466,000
Non-Credit OTTI	0	[1]	0	[2]
Collateralized Debt Obligations [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fixed income investments, fair value	$10,700,000		$18,700,000
[1]	Represents total OTTI recognized in accumulated other comprehensive income. It does not include the change in fair value subsequent to the impairment measurement date. At SeptemberB 30, 2014, the gross unrealized loss related to fixed income investments for which a non-credit OTTI was recognized in accumulated other comprehensive income was nil.
[2]	Represents total OTTI recognized in accumulated other comprehensive income. It does not include the change in fair value subsequent to the impairment measurement date. At DecemberB 31, 2013, the gross unrealized loss related to fixed income investments for which a non-credit OTTI was recognized in accumulated other comprehensive income was $0.1 million.
[3]	Balances include amounts related to collateralized debt obligations held with total fair values of $10.7 million.
[4]	Balances include amounts related to collateralized debt obligations held with total fair values of $18.7 million.

Investments_Available_For_Sale

Investments (Available For Sale Securities In An Unrealized Loss Position) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, 12 months or greater	($11,100)	($5,800)	[1]
Unrealized losses	-19,100	-49,600	[1]
US Government and Agencies Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	-559	-7,359	[1]
Fair value, less than 12 months	95,967	382,593
Unrealized losses, 12 months or greater	-2,418	-260	[1]
Fair value, 12 months or greater	95,856	6,050
Unrealized losses	-2,977	-7,619	[1]
Fair value	191,823	388,643
US State and Municipal Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	-78	-395	[1]
Fair value, less than 12 months	7,261	20,452
Unrealized losses, 12 months or greater	-79	0	[1]
Fair value, 12 months or greater	6,835	0
Unrealized losses	-157	-395	[1]
Fair value	14,096	20,452
Foreign Government Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	-204	-1,981	[1]
Fair value, less than 12 months	43,104	139,503
Unrealized losses, 12 months or greater	-169	-25	[1]
Fair value, 12 months or greater	23,314	5,261
Unrealized losses	-373	-2,006	[1]
Fair value	66,418	144,764
Government Guaranteed Corporate Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	'	-50	[1]
Fair value, less than 12 months	'	13,326
Unrealized losses, 12 months or greater	'	0	[1]
Fair value, 12 months or greater	'	0
Unrealized losses	'	-50	[1]
Fair value	'	13,326
Corporate Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	-3,026	-5,959	[1]
Fair value, less than 12 months	432,053	478,287
Unrealized losses, 12 months or greater	-1,764	-552	[1]
Fair value, 12 months or greater	97,104	28,690
Unrealized losses	-4,790	-6,511	[1]
Fair value	529,157	506,977
Residential Mortgage Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	-593	-17,542	[1]
Fair value, less than 12 months	168,976	514,702
Unrealized losses, 12 months or greater	-3,980	-4,357	[1]
Fair value, 12 months or greater	152,520	102,446
Unrealized losses	-4,573	-21,899	[1]
Fair value	321,496	617,148
Commercial Mortgage Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	-1,186	-7,681	[1]
Fair value, less than 12 months	200,660	384,548
Unrealized losses, 12 months or greater	-2,341	-328	[1]
Fair value, 12 months or greater	93,769	16,804
Unrealized losses	-3,527	-8,009	[1]
Fair value	294,429	401,352
Collateralized Loan and Debt Obligations [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	-174	-48	[1]
Fair value, less than 12 months	95,995	20,733
Unrealized losses, 12 months or greater	-51	-152	[1]
Fair value, 12 months or greater	1,467	2,379
Unrealized losses	-225	-200	[1]
Fair value	97,462	23,112
Asset-backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	-264	-703	[1]
Fair value, less than 12 months	156,553	157,172
Unrealized losses, 12 months or greater	-268	-152	[1]
Fair value, 12 months or greater	29,991	7,011
Unrealized losses	-532	-855	[1]
Fair value	186,544	164,183
Fixed Maturities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	'	-41,718	[1]
Fair value, less than 12 months	'	2,111,316
Unrealized losses, 12 months or greater	'	-5,826	[1]
Fair value, 12 months or greater	'	168,641
Unrealized losses	'	-47,544	[1]
Fair value	'	2,279,957
Short-term Investments [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	'	-2	[1]
Fair value, less than 12 months	'	2,468
Unrealized losses, 12 months or greater	'	0	[1]
Fair value, 12 months or greater	'	0
Unrealized losses	'	-2	[1]
Fair value	'	2,468
Fixed Income Investments [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	-6,084	-41,720	[1]
Fair value, less than 12 months	1,200,569	2,113,784
Unrealized losses, 12 months or greater	-11,070	-5,826	[1]
Fair value, 12 months or greater	500,856	168,641
Unrealized losses	-17,154	-47,546	[1]
Fair value	1,701,425	2,282,425
Equity Investments [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	-1,861	-1,995	[1]
Fair value, less than 12 months	40,720	36,751
Unrealized losses, 12 months or greater	-20	0	[1]
Fair value, 12 months or greater	141	0
Unrealized losses	-1,881	-1,995	[1]
Fair value	40,861	36,751
Preferred Equity Investments [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	-37	-79	[1]
Fair value, less than 12 months	5,676	2,987
Unrealized losses, 12 months or greater	0	0	[1]
Fair value, 12 months or greater	0	0
Unrealized losses	-37	-79	[1]
Fair value	5,676	2,987
Short-term Fixed Income Fund [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	-1	'
Fair value, less than 12 months	2,899	'
Unrealized losses, 12 months or greater	0	'
Fair value, 12 months or greater	0	'
Unrealized losses	-1	'
Fair value	2,899	'
Equity Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized losses, less than 12 months	-1,899	-2,074	[1]
Fair value, less than 12 months	49,295	39,738
Unrealized losses, 12 months or greater	-20	0	[1]
Fair value, 12 months or greater	141	0
Unrealized losses	-1,919	-2,074	[1]
Fair value	$49,436	$39,738
[1]	Gross unrealized losses include unrealized losses on non-OTTI and non-credit OTTI securities recognized in accumulated other comprehensive income at DecemberB 31, 2013.

Investments_Analysis_Of_OTTI_D

Investments (Analysis Of OTTI) (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
Investments [Abstract]	'	'	'	'
Total other-than-temporary impairment losses	($102)	($190)	($411)	($1,575)
Portion of loss recognized in other comprehensive (loss) income	0	0	0	0
Net impairment losses recognized in earnings	($102)	($190)	($411)	($1,575)

Investments_Credit_Losses_Roll

Investments (Credit Losses 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
Investments [Abstract]	'	'	'	'
Beginning balance	($1,441)	($1,769)	($1,553)	($2,000)
Addition for the amount related to the credit loss for which an other-than-temporary impairment was not previously recognized	0	0	0	0
Addition for the amount related to the credit loss for which an other-than-temporary impairment was previously recognized	0	0	0	0
Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security	0	0	0	0
Reductions for securities sold during the period	579	113	691	344
Ending balance	($862)	($1,656)	($862)	($1,656)

Fair_Value_Measurement_Narrati

Fair Value Measurement (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Dec. 31, 2013
					Fair Value, Inputs, Level 3 [Member]	Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'	'
Transfers into Level 3	$2,198,000	$7,903,000	$7,201,000	$11,550,000	'	'
Transfers out of Level 3	-4,961,000	-1,202,000	-6,813,000	-1,763,000	'	'
Percentage of level 3 assets	'	'	'	'	11.40%	10.90%
Net impairment losses recognized in earnings	102,000	190,000	411,000	1,575,000	0	'
Amount of transfers from Level 1 to Level 2	$6,600,000	'	$6,600,000	'	'	'

Fair_Value_Measurement_Schedul

Fair Value Measurement (Schedule Of Available For Sale Investments, Other Investments, Derivative Instruments And Debt) (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Assets	'		'
Fixed maturity investments	$4,871,420		$4,823,964
Short-term investments	11,844		35,028
Equity securities	267,728		252,466
Other investments	658,678		617,478
Other assets (see Note 7)	147,488		108,272
Total assets	5,957,158		5,837,208
Liabilities	'		'
Other liabilities (see Note 7)	95,704		49,452
Debt	615,568		575,115
Total liabilities	711,272		624,567
Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Short-term investments	0		0
Other investments	0		0
Other assets (see Note 7)	0		0
Total assets	132,318		146,754
Liabilities	'		'
Other liabilities (see Note 7)	0		0
Debt	0		0
Total liabilities	0		0
Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Short-term investments	11,844		35,028
Other investments	0		0
Other assets (see Note 7)	132,666		94,234
Total assets	5,144,147		5,051,610
Liabilities	'		'
Other liabilities (see Note 7)	79,788		29,883
Debt	615,568		575,115
Total liabilities	695,356		604,998
Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Short-term investments	0		0
Other investments	658,678		617,478
Other assets (see Note 7)	14,822		14,038
Total assets	680,693		638,844
Liabilities	'		'
Other liabilities (see Note 7)	15,916		19,569
Debt	0		0
Total liabilities	15,916		19,569
US Government and Agencies Securities [Member]	'		'
Assets	'		'
Fixed maturity investments	514,672		769,343
US Government and Agencies Securities [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		20,248
US Government and Agencies Securities [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Fixed maturity investments	514,672		749,095
US Government and Agencies Securities [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		0
US State and Municipal Debt Securities [Member]	'		'
Assets	'		'
Fixed maturity investments	31,487		26,854
US State and Municipal Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		0
US State and Municipal Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Fixed maturity investments	31,487		26,854
US State and Municipal Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		0
Foreign Government Securities [Member]	'		'
Assets	'		'
Fixed maturity investments	205,693		182,647
Foreign Government Securities [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		0
Foreign Government Securities [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Fixed maturity investments	205,693		182,647
Foreign Government Securities [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		0
Government Guaranteed Corporate Securities [Member]	'		'
Assets	'		'
Fixed maturity investments	46,201		35,145
Government Guaranteed Corporate Securities [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		0
Government Guaranteed Corporate Securities [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Fixed maturity investments	46,201		35,145
Government Guaranteed Corporate Securities [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		0
Corporate Securities [Member]	'		'
Assets	'		'
Fixed maturity investments	1,280,366		1,227,299
Corporate Securities [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		0
Corporate Securities [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Fixed maturity investments	1,279,666		1,226,553
Corporate Securities [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Fixed maturity investments	700		746
Residential Mortgage Backed Securities [Member]	'		'
Assets	'		'
Fixed maturity investments	1,203,322		1,187,191
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		0
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Fixed maturity investments	1,203,294		1,186,943
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Fixed maturity investments	28		248
Commercial Mortgage Backed Securities [Member]	'		'
Assets	'		'
Fixed maturity investments	965,696		947,677
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		0
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Fixed maturity investments	962,868		946,794
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Fixed maturity investments	2,828		883
Collateralized Loan and Debt Obligations [Member]	'		'
Assets	'		'
Fixed maturity investments	207,214	[1]	94,552	[2]
Collateralized Loan and Debt Obligations [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		0
Collateralized Loan and Debt Obligations [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Fixed maturity investments	206,574		92,095
Collateralized Loan and Debt Obligations [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Fixed maturity investments	640		2,457
Asset-backed Securities [Member]	'		'
Assets	'		'
Fixed maturity investments	416,769		353,256
Asset-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		0
Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Fixed maturity investments	413,772		350,262
Asset-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Fixed maturity investments	2,997		2,994
Fixed Maturities [Member]	'		'
Assets	'		'
Fixed maturity investments	4,871,420		4,823,964
Fixed Maturities [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Fixed maturity investments	0		20,248
Fixed Maturities [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Fixed maturity investments	4,864,227		4,796,388
Fixed Maturities [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Fixed maturity investments	7,193		7,328
Equity Investments [Member]	'		'
Assets	'		'
Equity securities	182,514		174,669
Equity Investments [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Equity securities	123,283		117,776
Equity Investments [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Equity securities	59,231		56,893
Equity Investments [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Equity securities	0		0
Emerging Market Debt Funds [Member]	'		'
Assets	'		'
Equity securities	61,862		60,844
Emerging Market Debt Funds [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Equity securities	0		0
Emerging Market Debt Funds [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Equity securities	61,862		60,844
Emerging Market Debt Funds [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Equity securities	0		0
Preferred Equity Investments [Member]	'		'
Assets	'		'
Equity securities	14,317		8,223
Preferred Equity Investments [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Equity securities	0		0
Preferred Equity Investments [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Equity securities	14,317		8,223
Preferred Equity Investments [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Equity securities	0		0
Short-term Fixed Income Fund [Member]	'		'
Assets	'		'
Equity securities	9,035		8,730
Short-term Fixed Income Fund [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Equity securities	9,035		8,730
Short-term Fixed Income Fund [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Equity securities	0		0
Short-term Fixed Income Fund [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Equity securities	0		0
Equity Securities [Member]	'		'
Assets	'		'
Equity securities	267,728		252,466
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]	'		'
Assets	'		'
Equity securities	132,318		126,506
Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]	'		'
Assets	'		'
Equity securities	135,410		125,960
Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]	'		'
Assets	'		'
Equity securities	$0		$0
[1]	Balances include amounts related to collateralized debt obligations held with total fair values of $10.7 million.
[2]	Balances include amounts related to collateralized debt obligations held with total fair values of $18.7 million.

Fair_Value_Measurement_Quantit

Fair Value Measurement (Quantitative Information Used As Level 3 Inputs) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014
			Energy Related Derivative [Member]	Energy Related Derivative [Member]	Simulation Valuation Technique [Member]	Fair Value, Inputs, Level 3 [Member]	Fair Value, Inputs, Level 3 [Member]	Fair Value, Inputs, Level 3 [Member]	Fair Value, Inputs, Level 3 [Member]
					Energy Related Derivative [Member]			Simulation Valuation Technique [Member]	Simulation Valuation Technique [Member]
								Maximum [Member]	Minimum [Member]
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]	'	'	'	'	'	'	'	'	'
Net weather and energy related derivative liabilities	$51,784,000	$58,820,000	'	'	($1,094,000)	'	'	'	'
Correlation	'	'	'	'	'	'	'	1	0
Weather curve	'	'	'	'	'	'	'	'2500	'400
Commodity curve	'	'	'	'	'	'	'	122.2	28.5
Derivatives recorded in other assets, fair value	147,488,000	108,272,000	14,822,000	14,038,000	'	14,822,000	14,038,000	'	'
Derivatives recorded in other liabilities, fair value	$95,704,000	$49,452,000	$15,916,000	$19,569,000	'	$15,916,000	$19,569,000	'	'

Fair_Value_Measurement_Reconci

Fair Value Measurement (Reconciliation Of The Beginning And Ending Balances For Fixed Maturity Investments, Other Investments, Other Assets and Other Liabilities Measured At Fair Value On A Recurring Basis Using Level 3 Inputs) (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
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'	'	'
Level 3, beginning of period	$669,149	$576,939	$638,844	$526,925
Total equity income and realized gains included in earnings	10,922	19,164	46,447	61,114
Total equity losses and losses included in earnings	-12,704	-5,879	-23,876	-17,944
Total income included in other underwriting income (loss)	3,180	0	18,396	0
Total loss included in other underwriting income (loss)	-5,235	0	-23,845	-1,182
Change in unrealized gains included in other comprehensive (loss) income	245	111	445	438
Change in unrealized losses included in other comprehensive (loss) income	-104	-62	-255	-270
Purchases	28,533	16,597	55,074	62,011
Issues	7,331	'	10,912	300
Sales	-14,914	-6,957	-35,657	-34,565
Settlements	-2,947	'	-6,180	'
Transfers into Level 3	2,198	7,903	7,201	11,550
Transfers out of Level 3	-4,961	-1,202	-6,813	-1,763
Level 3, end of period	680,693	606,614	680,693	606,614
Fixed Maturity Investments [Member]	'	'	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'	'	'
Level 3, beginning of period	9,515	7,546	7,328	8,497
Total equity income and realized gains included in earnings	9	56	62	104
Total equity losses and losses included in earnings	-6	-15	-32	-17
Total income included in other underwriting income (loss)	0	0	0	0
Total loss included in other underwriting income (loss)	0	0	0	0
Change in unrealized gains included in other comprehensive (loss) income	245	111	445	438
Change in unrealized losses included in other comprehensive (loss) income	-104	-62	-255	-270
Purchases	842	0	842	0
Issues	0	'	0	0
Sales	-545	-1,879	-1,585	-6,081
Settlements	0	'	0	'
Transfers into Level 3	2,198	7,903	7,201	11,550
Transfers out of Level 3	-4,961	-1,202	-6,813	-1,763
Level 3, end of period	7,193	12,458	7,193	12,458
Other Investments [Member]	'	'	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'	'	'
Level 3, beginning of period	648,642	569,393	617,478	517,546
Total equity income and realized gains included in earnings	10,913	19,108	46,385	61,010
Total equity losses and losses included in earnings	-12,698	-5,864	-23,844	-17,927
Total income included in other underwriting income (loss)	0	0	0	0
Total loss included in other underwriting income (loss)	0	0	0	0
Change in unrealized gains included in other comprehensive (loss) income	0	0	0	0
Change in unrealized losses included in other comprehensive (loss) income	0	0	0	0
Purchases	26,190	16,597	52,731	62,011
Issues	0	'	0	0
Sales	-14,369	-5,078	-34,072	-28,484
Settlements	0	'	0	'
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Level 3, end of period	658,678	594,156	658,678	594,156
Other Assets [Member]	'	'	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'	'	'
Level 3, beginning of period	10,992	0	14,038	882
Total equity income and realized gains included in earnings	0	0	0	0
Total equity losses and losses included in earnings	0	0	0	0
Total income included in other underwriting income (loss)	3,180	0	18,396	0
Total loss included in other underwriting income (loss)	-5,235	0	-23,845	-1,182
Change in unrealized gains included in other comprehensive (loss) income	0	0	0	0
Change in unrealized losses included in other comprehensive (loss) income	0	0	0	0
Purchases	1,501	0	1,501	0
Issues	7,331	'	10,912	300
Sales	0	0	0	0
Settlements	-2,947	'	-6,180	'
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Level 3, end of period	14,822	0	14,822	0
Other Liabilities [Member]	'	'	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'	'	'
Level 3, beginning of period	-10,284	0	-19,569	-1,922
Total equity income and realized gains included in earnings	0	0	0	0
Total equity losses and losses included in earnings	0	0	0	0
Total income included in other underwriting income (loss)	4,794	0	24,842	2,354
Total loss included in other underwriting income (loss)	-3,719	0	-20,672	0
Change in unrealized gains included in other comprehensive (loss) income	0	0	0	0
Change in unrealized losses included in other comprehensive (loss) income	0	0	0	0
Purchases	-751	0	-751	0
Issues	-10,917	'	-18,080	-432
Sales	0	0	0	0
Settlements	4,961	'	18,314	'
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Level 3, end of period	($15,916)	$0	($15,916)	$0

Earnings_Per_Share_Schedule_Of

Earnings Per Share (Schedule Of Computing Basic And Diluted 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
Net income available to common and participating common shareholders	$68,046		$75,228		$239,313		$220,170
Less amount allocated to participating common shareholders	-1,930	[1]	-1,997	[1]	-6,907	[1]	-4,742	[1]
Net income allocated to common shareholders	$66,116		$73,231		$232,406		$215,428
Weighted average shares - basic	43,464,790		43,099,841		43,332,461		42,719,837
Weighted average shares - diluted	43,510,415		43,100,139		43,355,792		42,720,431
Basic earnings per common share	$1.52		$1.70		$5.36		$5.04
Diluted earnings per common share	$1.52		$1.70		$5.36		$5.04
Employee Stock Option [Member]	'		'		'		'
Share equivalents	45,625		0		23,237		0
Restricted Stock [Member]	'		'		'		'
Share equivalents	0		298		94		594
[1]	Represents earnings attributable to holders of unvested restricted shares issued under the Company's equity compensation plan that are considered participating. In periods of loss, no losses are allocated to participating common shareholders (unvested restricted shares).

Earnings_Per_Share_Schedule_Of1

Earnings Per Share (Schedule Of Dividends Declared) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Dividends Declared [Line Items]	'	'	'	'
Dividends declared per common share	$0.34	$0.32	$1.02	$0.96
Series A Preferred Stock [Member]	'	'	'	'
Dividends Declared [Line Items]	'	'	'	'
Dividends declared per preferred share	$0.48	$0.48	$1.45	$1.45
Series B Preferred Stock [Member]	'	'	'	'
Dividends Declared [Line Items]	'	'	'	'
Dividends declared per preferred share	$0.47	$0.47	$1.41	$1.41

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income (Schedule Of Changes In Accumulated Other Comprehensive Income By Component) (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
Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Beginning balance	$136,038		$31,438		$62,731		$152,463
Other comprehensive (loss) income before reclassifications	-45,504		31,276		33,714		-75,058
Amounts reclassified from accumulated other comprehensive income	-9,235	[1]	6,743	[1]	-15,146	[1]	-7,948
Other comprehensive (loss) income	-54,739		38,019		18,568		-83,006
Ending balance	81,299		69,457		81,299		69,457
Gains and losses on cash flow hedges [Member]	'		'		'		'
Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Beginning balance	-1,810		-1,899		-1,855		-1,944
Other comprehensive (loss) income before reclassifications	0		0		0		0
Amounts reclassified from accumulated other comprehensive income	22	[1]	22	[1]	67	[1]	67	[1]
Other comprehensive (loss) income	22		22		67		67
Ending balance	-1,788		-1,877		-1,788		-1,877
Unrealized gains and losses on available for sale securities [Member]	'		'		'		'
Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Beginning balance	106,989		30,636		45,950		141,731
Other comprehensive (loss) income before reclassifications	-25,100		22,358		41,895		-74,001
Amounts reclassified from accumulated other comprehensive income	-9,257	[1]	6,721	[1]	-15,213	[1]	-8,015	[1]
Other comprehensive (loss) income	-34,357		29,079		26,682		-82,016
Ending balance	72,632		59,715		72,632		59,715
Foreign currency translation adjustments [Member]	'		'		'		'
Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Beginning balance	30,859		2,701		18,636		12,676
Other comprehensive (loss) income before reclassifications	-20,404		8,918		-8,181		-1,057
Amounts reclassified from accumulated other comprehensive income	0	[1]	0	[1]	0	[1]	0	[1]
Other comprehensive (loss) income	-20,404		8,918		-8,181		-1,057
Ending balance	$10,455		$11,619		$10,455		$11,619
[1]	All amounts are net of tax.

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income (Schedule Of Reclassifications Out Of Accumulated Other Comprehensive 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]	'	'	'	'
Interest expense	$13,127	$9,048	$31,910	$27,138
Net realized and unrealized investment gains (losses)	9,788	-6,640	18,071	9,967
Net impairment losses recognized in earnings	-102	-190	-411	-1,575
Total before income taxes	71,952	85,687	260,143	250,291
Income tax benefit (expense)	4,282	-2,271	3,734	-5,557
Total net of income taxes	76,234	83,416	263,877	244,734
Gains and losses on cash flow hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Interest expense	22	22	67	67
Total before income taxes	22	22	67	67
Income tax benefit (expense)	0	0	0	0
Total net of income taxes	22	22	67	67
Unrealized gains and losses on available for sale securities [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Net realized and unrealized investment gains (losses)	-9,208	6,999	-15,539	-10,267
Net impairment losses recognized in earnings	102	190	411	1,575
Total before income taxes	-9,106	7,189	-15,128	-8,692
Income tax benefit (expense)	195	-468	-85	677
Total net of income taxes	($8,911)	$6,721	($15,213)	($8,015)

Derivatives_Schedule_Of_Deriva

Derivatives (Schedule Of Derivative Fair Value And Notional Amount) (Details) (USD $)

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

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

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Maximum [Member]

Foreign Exchange Forward [Member]

Foreign Exchange Forward [Member]

Credit Default Swap [Member]

Credit Default Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swaption [Member]

Interest Rate Swaption [Member]

TBA [Member]

TBA [Member]

Energy and weather contracts [Member]

Energy and weather contracts [Member]

Interest Rate Future [Member]

Interest Rate Future [Member]

Derivatives, Fair Value [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivatives recorded in other assets, fair value

$147,488,000

$108,272,000

'

$1,128,000

$251,000

$11,000

$0

$211,000

$124,000

$0

$39,000

$131,316,000

$93,820,000

$14,822,000

$14,038,000

'

'

Derivatives recorded in other liabilities, fair value

95,704,000

49,452,000

'

312,000

172,000

'

'

731,000

933,000

18,000

543,000

78,727,000

28,218,000

15,916,000

19,569,000

0

17,000

Net derivative asset, fair value

51,784,000

58,820,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivatives recorded in other assets, notional principal amount

'

'

'

40,923,000

19,269,000

1,785,000

0

72,700,000

16,100,000

0

24,338,000

127,255,000

93,840,000

79,846,000

53,986,000

'

'

Derivatives recorded in other liabilities, notional principal amount

'

'

'

23,641,000

15,861,000

'

'

11,782,000

12,193,000

56,216,000

361,455,000

76,000,000

28,000,000

115,574,000

66,113,000

0

103,935,000

Original term of credit default swap, in years

'

'

'5 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative assets traded under master netting agreements

147,500,000

108,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative liabilities traded under master netting agreements

$95,700,000

$49,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivatives_Schedule_Of_Deriva1

Derivatives (Schedule Of Derivative Gain (Loss)) (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
Derivative [Line Items]	'	'	'	'
Derivatives included in net realized and unrealized investment gains (losses)	$580	$358	$2,532	($300)
Total gains from derivatives	3,578	235	4,833	1,079
Foreign Exchange Forward [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in net foreign exchange losses from foreign exchange forward contracts	1,214	-123	815	207
Interest Rate Future [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in net realized and unrealized investment gains (losses)	0	112	136	64
Credit Default Swap [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in net realized and unrealized investment gains (losses)	6	-68	20	49
Interest Rate Swap [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in net realized and unrealized investment gains (losses)	384	-67	-698	-228
Interest Rate Swaption [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in net realized and unrealized investment gains (losses)	-3	392	425	291
TBA [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in net realized and unrealized investment gains (losses)	193	-11	2,649	-476
Energy and weather contracts [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in other underwriting income (loss) from energy and weather contracts	$1,784	$0	$1,486	$1,172

StockBased_Employee_Compensati1

Stock-Based Employee Compensation And Other Stock Plans (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Number of options granted	0	0	0	800,000
Number of options expired	0	0	0	0
Number of options vested	0	0	160,000	160,000
Number of options exercised	0	0	15,000	24,501
Total intrinsic value of options exercised	'	'	$300,000	$500,000
Proceeds from stock options exercised	'	'	500,000	600,000
Options weighted average grant date fair value	'	'	'	10,200,000
Number of restricted shares and RSUs granted	39,080	8,453	472,497	1,079,108
Restricted shares and RSUs weighted average grant date fair value	2,100,000	400,000	24,800,000	50,700,000
Aggregate fair value of restricted shares and RSUs vested	200,000	100,000	18,700,000	17,000,000
Expenses related to employee stock purchase plan	62,000	42,000	172,000	124,000
Employee Stock Option [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Compensation costs recognized	600,000	1,000,000	2,500,000	3,500,000
Compensation costs not yet recognized - stock options	3,200,000	6,700,000	3,200,000	6,700,000
Restricted Stock [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Compensation costs recognized	5,700,000	2,600,000	21,500,000	16,100,000
Compensation costs not yet recognized - restricted stock	$27,700,000	$31,600,000	$27,700,000	$31,600,000

Segment_Reporting_Summary_Of_T

Segment Reporting (Summary Of The Segment Revenues, Results And 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	Dec. 31, 2013
Segment Reporting Information [Line Items]	'	'	'	'	'
Gross premiums written	$626,110	$544,363	$2,473,050	$2,294,435	'
Ceded premiums written	-236,004	-149,030	-772,812	-525,566	'
Net premiums written	390,106	395,333	1,700,238	1,768,869	'
Net premiums earned	514,895	553,545	1,392,699	1,516,997	'
Other underwriting income (loss)	2,123	-943	-3,939	694	'
Total revenue	517,018	552,602	1,388,760	1,517,691	'
Net losses and loss expenses	290,269	339,036	726,361	917,064	'
Acquisition expenses	93,392	78,775	244,150	222,279	'
General and administrative expenses	80,915	67,470	240,576	215,307	'
Total expenses	464,576	485,281	1,211,087	1,354,650	'
Underwriting (loss) income	52,442	67,321	177,673	163,041	'
Net loss ratio	56.40%	61.30%	52.20%	60.40%	'
Acquisition expense ratio	18.10%	14.20%	17.50%	14.70%	'
General and administrative expense ratio	15.70%	12.20%	17.30%	14.20%	'
Combined ratio	90.20%	87.70%	87.00%	89.30%	'
Reserve for losses and loss expenses	3,897,483	4,052,102	3,897,483	4,052,102	4,002,259
Insurance [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Gross premiums written	420,343	344,819	1,394,145	1,274,703	'
Ceded premiums written	-222,704	-120,481	-674,441	-454,169	'
Net premiums written	197,639	224,338	719,704	820,534	'
Net premiums earned	253,583	291,477	616,167	710,507	'
Other underwriting income (loss)	0	0	0	0	'
Total revenue	253,583	291,477	616,167	710,507	'
Net losses and loss expenses	196,677	228,409	434,777	543,717	'
Acquisition expenses	20,170	18,440	47,559	48,024	'
General and administrative expenses	44,957	35,641	133,930	114,792	'
Total expenses	261,804	282,490	616,266	706,533	'
Underwriting (loss) income	-8,221	8,987	-99	3,974	'
Net loss ratio	77.50%	78.40%	70.60%	76.40%	'
Acquisition expense ratio	8.00%	6.30%	7.70%	6.80%	'
General and administrative expense ratio	17.70%	12.20%	21.70%	16.20%	'
Combined ratio	103.20%	96.90%	100.00%	99.40%	'
Reserve for losses and loss expenses	2,134,985	2,146,136	2,134,985	2,146,136	'
Reinsurance [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Gross premiums written	205,767	199,544	1,078,905	1,019,732	'
Ceded premiums written	-13,300	-28,549	-98,371	-71,397	'
Net premiums written	192,467	170,995	980,534	948,335	'
Net premiums earned	261,312	262,068	776,532	806,490	'
Other underwriting income (loss)	2,123	-943	-3,939	694	'
Total revenue	263,435	261,125	772,593	807,184	'
Net losses and loss expenses	93,592	110,627	291,584	373,347	'
Acquisition expenses	73,222	60,335	196,591	174,255	'
General and administrative expenses	35,958	31,829	106,646	100,515	'
Total expenses	202,772	202,791	594,821	648,117	'
Underwriting (loss) income	60,663	58,334	177,772	159,067	'
Net loss ratio	35.80%	42.30%	37.60%	46.30%	'
Acquisition expense ratio	28.00%	23.00%	25.30%	21.60%	'
General and administrative expense ratio	13.80%	12.10%	13.70%	12.50%	'
Combined ratio	77.60%	77.40%	76.60%	80.40%	'
Reserve for losses and loss expenses	$1,762,498	$1,905,966	$1,762,498	$1,905,966	'

Segment_Reporting_Schedule_Of_

Segment Reporting (Schedule Of Segment Results To Income Before Income Taxes) (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
Segment Reporting [Abstract]	'	'	'	'
Total underwriting income	$52,442	$67,321	$177,673	$163,041
Net investment income	25,357	38,097	105,649	119,870
Net foreign exchange losses	-783	-2,201	-4,066	-8,496
Net realized and unrealized investment gains	9,788	-6,640	18,071	9,967
Net impairment losses recognized in earnings	-102	-190	-411	-1,575
Amortization of intangibles	-1,623	-1,652	-4,863	-5,378
Interest expense	-13,127	-9,048	-31,910	-27,138
Income before income taxes	$71,952	$85,687	$260,143	$250,291

Segment_Reporting_Schedule_Of_1

Segment Reporting (Schedule Of Gross And Net Premiums By Line Of Business) (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
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	$626,110	$544,363	$2,473,050	$2,294,435
Net premiums written	390,106	395,333	1,700,238	1,768,869
Insurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	420,343	344,819	1,394,145	1,274,703
Net premiums written	197,639	224,338	719,704	820,534
Agriculture Insurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	188,011	200,062	796,445	896,169
Net premiums written	103,536	120,617	431,007	546,284
Casualty And Other Specialty Insurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	144,706	95,862	366,329	239,943
Net premiums written	58,390	72,431	189,876	179,065
Professional Lines Insurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	62,631	34,221	176,061	93,481
Net premiums written	20,216	20,972	64,632	62,963
Property Insurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	24,995	14,674	55,310	45,110
Net premiums written	15,497	10,318	34,189	32,222
Reinsurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	205,767	199,544	1,078,905	1,019,732
Net premiums written	192,467	170,995	980,534	948,335
Catastrophe Reinsurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	47,173	38,676	332,193	341,973
Net premiums written	41,157	12,551	243,531	281,990
Casualty Reinsurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	23,409	27,649	139,266	211,458
Net premiums written	23,409	27,648	137,669	210,030
Property Reinsurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	73,807	91,653	283,107	288,448
Net premiums written	73,807	90,528	283,015	283,455
Professional Lines Reinsurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	21,520	25,670	131,256	50,505
Net premiums written	21,520	25,670	131,256	50,505
Specialty Reinsurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	39,858	15,896	193,083	127,348
Net premiums written	$32,574	$14,598	$185,063	$122,355

Commitments_And_Contingencies_1

Commitments And Contingencies (Narrative) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]	'	'
Securities pledged as collateral obligation	$130.10	$146.10
Cash and investments pledged under letters of credit facility	237.9	302.7
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverables	731.9	758
Ceded Credit Risk, Secured [Member]	'	'
Ceded Credit Risk [Line Items]	'	'
Reinsurance recoverables	$87.60	$14.20

Commitments_And_Contingencies_2

Commitments And Contingencies (Schedule Of Percentage Of Net Premiums) (Details)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Revenue from External Customer [Line Items]	'	'
Percentage of net premium written	50.50%	45.90%
Aon Benfield [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Percentage of net premium written	15.40%	18.50%
Willis Companies [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Percentage of net premium written	14.20%	12.40%
Marsh & Mclennan Companies, Inc. [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Percentage of net premium written	20.90%	15.00%

Commitments_And_Contingencies_3

Commitments And Contingencies (LOC) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Other Commitments [Line Items]	'	'
Amount of letters of credit outstanding	$202.90	$260.30
Maximum borrowing capacity	700	'
ANZ [Member]	'	'
Other Commitments [Line Items]	'	'
Amount of letters of credit outstanding	1.4	0
Maximum borrowing capacity	$50	'

Commitments_And_Contingencies_4

Commitments And Contingencies (Option) (Details) (USD $)	0 Months Ended	9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Jun. 02, 2014	Sep. 30, 2014
Option Indexed to Issuer's Equity [Line Items]	'	'
Number of individuals investor has right to nominate for BOD after option is exercised	1	'
Specified individuals that investor can nominate to BOD which are not subject to board approval	2	'
Percentage of stock acquired	40.00%	'
Payment due to investors	$26.30	'
Call Option [Member]	'	'
Option Indexed to Issuer's Equity [Line Items]	'	'
Acquisition percentage	95.00%	'
Amount of equity able to be purchased under option	250	'
Strike price of option	$50.03	'
Period option is exercisable, in days	'	'60
Period transfer of shares purchased under option is restricted, in months	'	'12
Call Option [Member] | Maximum [Member] | Chief Executive Officer [Member]	'	'
Option Indexed to Issuer's Equity [Line Items]	'	'
Amount of equity issuance subject to exception	25	'
Call Option [Member] | Maximum [Member] | Investor [Member]	'	'
Option Indexed to Issuer's Equity [Line Items]	'	'
Amount of equity issuance subject to exception	$100	'

Commitments_And_Contingencies_5

Commitments And Contingencies (Warrants) (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Jun. 02, 2014
Warrants and Rights Note Disclosure [Abstract]	'	'
Exercise price of warrant	'	$58.86
Term of warrants, in years	'10	'
Percentage of number of ordinary shares acquired available under option	'	38.50%

Commitments_And_Contingencies_6

Commitments And Contingencies (Agreement) (Details) (Chief Executive Officer [Member], USD $)	0 Months Ended
In Millions, except Per Share data, unless otherwise specified	Jun. 02, 2014
Chief Executive Officer [Member]	'
Commitment To Purchase Common Shares [Line Items]	'
Amount of equity committed to purchase	$25
Price per share of commitment to purchase common shares	$53.51

Commitments_And_Contingencies_7

Commitments And Contingencies (Deposits) (Details) (UNITED STATES [Member], USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
UNITED STATES [Member]	'	'
Statutory Accounting Practices [Line Items]	'	'
Assets Held by Insurance Regulators	$273.10	$273.70

Commitments_And_Contingencies_8

Commitments And Contingencies (Schedule Of Future Minimum Lease Commitments) (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Commitments and Contingencies Disclosure [Abstract]	'	'
2015	$16,066,000	'
2016	13,527,000	'
2017	11,957,000	'
2018	11,465,000	'
2019	10,809,000	'
2020 and thereafter	36,377,000	'
Total	100,201,000	'
Total lease expenses under operating leases	$11,600,000	$11,200,000

Debt_And_Financing_Arrangement1

Debt And Financing Arrangements (Narrative) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Jun. 25, 2014	Sep. 30, 2014
In Millions, unless otherwise specified			Bridge Facility [Member]	Bridge Facility [Member]
Line of Credit Facility [Line Items]	'	'	'	'
Maximum borrowing capacity	$700	'	'	$1,000
Amount outstanding under facility	0	'	'	'
Amount of letters of credit outstanding	$202.90	$260.30	'	'
Term of bridge facility, in days	'	'	'364 days	'