Endurance Specialty (ENH) 10-Q 7 Aug 14 2014 Q2 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	6 Months Ended
	Jun. 30, 2014	Aug. 01, 2014
Document and Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
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	'	44,719,594

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
ASSETS	'	'
Fixed maturity investments, available for sale at fair value (amortized cost: $4,912,191 and $4,802,580 at June 30, 2014 and December 31, 2013, respectively)	$4,993,099	$4,823,964
Short-term investments, available for sale at fair value (amortized cost: $24,564 and $35,029 at June 30, 2014 and December 31, 2013, respectively)	24,564	35,028
Equity securities, available for sale at fair value (cost: $249,463 and $227,828 at June 30, 2014 and December 31, 2013, respectively)	287,642	252,466
Other investments	648,642	617,478
Total investments	5,953,947	5,728,936
Cash and cash equivalents	801,028	845,851
Premiums receivable, net	1,380,858	669,198
Insurance and reinsurance balances receivable	134,750	127,722
Deferred acquisition costs	257,262	186,027
Prepaid reinsurance premiums	424,133	187,209
Reinsurance recoverables on unpaid losses	606,140	593,755
Reinsurance recoverable on paid losses	145,694	164,220
Accrued investment income	26,385	24,104
Goodwill and intangible assets	162,178	165,378
Deferred tax asset	45,782	51,703
Net receivable on sales of investments	67,578	54,910
Other assets	172,912	179,109
Total assets	10,178,647	8,978,122
LIABILITIES	'	'
Reserve for losses and loss expenses	3,963,393	4,002,259
Reserve for unearned premiums	1,689,819	1,018,851
Deposit liabilities	21,987	19,458
Reinsurance balances payable	378,295	181,061
Debt	527,714	527,478
Net payable on purchases of investments	272,696	129,047
Other liabilities	209,068	213,419
Total liabilities	7,062,972	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 - 44,705,758 issued and outstanding (2013 - 44,368,742)	44,706	44,369
Additional paid-in capital	583,691	569,116
Accumulated other comprehensive income	136,038	62,731
Retained earnings	2,334,040	2,193,133
Total shareholders' equity	3,115,675	2,886,549
Total liabilities and shareholders' equity	$10,178,647	$8,978,122

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Available for Sale Securities	'	'
Available for sale securities, fixed maturity investments, amortized cost	$4,912,191	$4,802,580
Available for sale, short-term investments, amortized cost	24,564	35,029
Equity securities, cost	249,463	227,828
Shareholders' Equity	'	'
Preferred stock, aggregate liquidation preference	$430,000	$430,000
Common stock, shares issued	44,705,758	44,368,742
Common stock, shares outstanding	44,705,758	44,368,742

Condensed_Consolidated_Stateme

Condensed Consolidated Statements Of Income And Comprehensive Income (Loss) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenues	'	'	'	'
Gross premiums written	$689,425	$572,710	$1,846,940	$1,750,072
Ceded premiums written	-177,998	-108,089	-536,808	-376,536
Net premiums written	511,427	464,621	1,310,132	1,373,536
Change in unearned premiums	-29,889	78,714	-432,328	-410,084
Net premiums earned	481,538	543,335	877,804	963,452
Net investment income	39,302	32,468	80,292	81,773
Net realized and unrealized investment gains	3,411	10,372	8,283	16,607
Total other-than-temporary impairment losses	-198	-579	-309	-1,385
Portion of loss recognized in other comprehensive income (loss)	0	0	0	0
Net impairment losses recognized in earnings	-198	-579	-309	-1,385
Other underwriting (loss) income	-4,824	888	-6,062	1,637
Total revenues	519,229	586,484	960,008	1,062,084
Expenses	'	'	'	'
Net losses and loss expenses	259,196	359,058	436,092	578,028
Acquisition expenses	78,601	71,868	150,758	143,504
General and administrative expenses	86,455	81,359	159,661	147,837
Amortization of intangibles	1,623	1,625	3,240	3,726
Net foreign exchange losses	319	3,368	3,283	6,295
Interest expense	9,732	9,052	18,783	18,090
Total expenses	435,926	526,330	771,817	897,480
Income before income taxes	83,303	60,154	188,191	164,604
Income tax (expense) benefit	-140	865	-548	-3,286
Net income	83,163	61,019	187,643	161,318
Preferred dividends	-8,188	-8,188	-16,376	-16,376
Net income available to common and participating common shareholders	74,975	52,831	171,267	144,942
Comprehensive income (loss)	'	'	'	'
Net income	83,163	61,019	187,643	161,318
Other comprehensive income (loss)	'	'	'	'
Net unrealized holding gains (losses) on investments arising during the period (net of other-than-temporary impairment losses recognized in other comprehensive income (loss), reclassification adjustment and applicable deferred income taxes of ($5,916) and $10,831 for the six months ended June 30, 2014 and 2013, respectively)	37,659	-106,249	61,039	-111,095
Foreign currency translation adjustments	8,998	219	12,223	-9,975
Reclassification adjustment for net losses on derivative designated as cash flow hedge included in net income	22	29	45	45
Other comprehensive income (loss)	46,679	-106,001	73,307	-121,025
Comprehensive income (loss)	$129,842	($44,982)	$260,950	$40,293
Per share data	'	'	'	'
Basic earnings per common share	$1.68	$1.21	$3.84	$3.34
Diluted earnings per common share	$1.68	$1.21	$3.84	$3.34
Dividend per common share	$0.34	$0.32	$0.68	$0.64

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements Of Income And Comprehensive Income (Loss) (Parenthetical) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Condensed Consolidated Statements Of Income And Comprehensive Income (Loss)	'	'
Other comprehensive income (loss), net unrealized holding gains (losses) on investments arising during the period, tax	($5,916)	$10,831

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements Of Changes In Shareholders' Equity (USD $)	Total	Preferred Shares [Member]	Common Shares [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]	Total 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
Net income	161,318	'	'	'	'	'	'	'	161,318
Issuance of common shares net of forfeitures	'	'	1,533	29,598	'	'	'	'	'
Repurchase of common shares	'	'	-318	-14,266	'	'	'	'	'
Settlement of equity awards	-2,923	'	'	-2,923	'	'	'	'	'
Stock-based compensation expense	'	'	'	15,931	'	'	'	'	'
Foreign currency translation adjustments	-9,975	'	'	'	-9,975	'	'	'	'
Net unrealized holding gains (losses) arising during the period, net of other-than-temporary impairment losses and reclassification adjustment	-111,095	'	'	'	'	-111,095	'	'	'
Net change from current period hedging transactions, net of reclassification adjustment	'	'	'	'	'	'	45	'	'
Dividends on preferred shares	-16,376	'	'	'	'	'	'	'	-16,376
Dividends on common shares	'	'	'	'	'	'	'	'	-28,015
Balance, end of period at Jun. 30, 2013	2,736,054	17,200	44,331	556,255	2,701	30,636	-1,899	31,438	2,086,830
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
Net income	187,643	'	'	'	'	'	'	'	187,643
Issuance of common shares net of forfeitures	'	'	337	900	'	'	'	'	'
Repurchase of common shares	'	'	0	0	'	'	'	'	'
Settlement of equity awards	-4,039	'	'	-4,039	'	'	'	'	'
Stock-based compensation expense	'	'	'	17,714	'	'	'	'	'
Foreign currency translation adjustments	12,223	'	'	'	12,223	'	'	'	'
Net unrealized holding gains (losses) arising during the period, net of other-than-temporary impairment losses and reclassification adjustment	61,039	'	'	'	'	61,039	'	'	'
Net change from current period hedging transactions, net of reclassification adjustment	'	'	'	'	'	'	45	'	'
Dividends on preferred shares	-16,376	'	'	'	'	'	'	'	-16,376
Dividends on common shares	'	'	'	'	'	'	'	'	-30,360
Balance, end of period at Jun. 30, 2014	$3,115,675	$17,200	$44,706	$583,691	$30,859	$106,989	($1,810)	$136,038	$2,334,040

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements Of Cash Flows (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Cash flows provided by operating activities	'	'
Net income	$187,643	$161,318
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Amortization of net premium on investments	22,253	27,804
Amortization of other intangibles and depreciation	10,673	9,479
Net realized and unrealized investment gains	-8,283	-16,607
Net impairment losses recognized in earnings	309	1,385
Deferred taxes	4	2,092
Stock-based compensation expense	17,714	15,931
Equity in earnings of other investments	-24,326	-29,839
Premiums receivable, net	-711,660	-669,866
Insurance and reinsurance balances receivable	-7,028	-5,742
Deferred acquisition costs	-71,235	-42,488
Prepaid reinsurance premiums	-236,924	-126,209
Reinsurance recoverable on unpaid losses	-12,385	97,763
Reinsurance recoverable on paid losses	18,526	-18,594
Accrued investment income	-2,281	1,762
Other assets	4,271	8,540
Reserve for losses and loss expenses	-38,866	-95,295
Reserve for unearned premiums	670,968	535,009
Deposit liabilities	2,529	-4,435
Reinsurance balances payable	197,234	151,739
Other liabilities	531	38,965
Net cash provided by operating activities	19,667	42,712
Cash flows used in investing activities	'	'
Proceeds from sales of available for sale investments	2,060,744	1,395,528
Proceeds from maturities and calls on available for sale investments	284,656	381,332
Proceeds from the redemption of other investments	19,703	23,406
Purchases of available for sale investments	-2,345,876	-1,894,444
Purchases of other investments	-26,541	-45,414
Net settlements of other assets	14,174	-18,584
Purchases of fixed assets	-25,706	-7,081
Net cash paid for subsidiary acquisition	-40	-347
Net cash flows used in investing activities	-18,886	-165,604
Cash flows used in financing activities	'	'
Issuance of common shares net of forfeitures	1,128	31,049
Repurchase of common shares	0	-14,584
Settlement of equity awards	-4,039	-2,923
Debt issuance costs paid	4,750	0
Proceeds from issuance of debt	373	408
Repayments and repurchases of debt	-244	-446
Dividends on preferred shares	-16,376	-16,376
Dividends on common shares	-30,343	-27,834
Net cash flows used in financing activities	-54,251	-30,706
Effect of exchange rate changes on cash and cash equivalents	8,647	-28,359
Net decrease in cash and cash equivalents	-44,823	-181,957
Cash and cash equivalents, beginning of period	845,851	1,124,019
Cash and cash equivalents, end of period	$801,028	$942,062

General

General	6 Months Ended
	Jun. 30, 2014
General	'
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	6 Months Ended
	Jun. 30, 2014
Summary Of Significant Accounting Policies	'
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 six months ended June 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	6 Months Ended
	Jun. 30, 2014
Investments	'
Investments	'
	3.       Investments
	Composition of Net Investment Income and of Invested Assets
	The components of net investment income for the three and six months ended June 30, 2014 and 2013 are as follows:
				Three Months Ended June 30,						Six Months Ended June 30,
					2014			2013			2014			2013
			Available for sale investments	$	31,619		$	28,666		$	61,946		$	58,147
			Other investments		10,785			6,780			24,327			29,839
			Cash and cash equivalents		511			840			1,297			1,291
				$	42,915		$	36,286		$	87,570		$	89,277
			Investment expenses		-3,613			-3,818			-7,278			-7,504
			Net investment income	$	39,302		$	32,468		$	80,292		$	81,773
	The following table summarizes the composition of the investment portfolio by investment type at June 30, 2014 and December 31, 2013:
					30-Jun-14						31-Dec-13
			Type of Investment		Fair Value		Percentage				Fair Value		Percentage
			Fixed maturity investments	$	4,993,099		76.2	%		$	4,823,964		74.2	%
			Cash and cash equivalents(1)		595,910		9.1	%			771,714		11.9	%
			Other investments(2)		648,642		9.9	%			617,478		9.5	%
			Short-term investments		24,564		0.4	%			35,028		0.5	%
			Equity securities		287,642		4.4	%			252,466		3.9	%
			Total	$	6,549,857		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 June 30, 2014 and December 31, 2013. In some cases, where bonds are unrated, the rating of the issuer has been applied.
					30-Jun-14						31-Dec-13
			Ratings(1)		Fair Value		Percentage				Fair Value		Percentage
			U.S. government and agencies securities	$	564,120		11.2	%		$	769,343		15.8	%
			AAA / Aaa		1,137,895		22.7	%			972,820		20	%
			AA / Aa		1,782,465		35.5	%			1,771,156		36.5	%
			A / A		999,084		19.9	%			895,549		18.4	%
			BBB		421,356		8.4	%			363,722		7.5	%
			Below BBB		99,558		2	%			66,791		1.4	%
			Not rated		13,185		0.3	%			19,611		0.4	%
			Total	$	5,017,663		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 June 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-Jun-14						31-Dec-13
					Amortized						Amortized
					Cost			Fair Value			Cost			Fair Value
		Due within one year		$	147,587		$	148,630		$	144,814		$	145,653
		Due after one year through five years			1,638,278			1,653,175			1,808,001			1,815,240
		Due after five years through ten years			384,738			393,528			290,391			288,486
		Due after ten years			47,496			50,325			26,344			26,937
		Residential mortgage-backed securities			1,202,234			1,225,675			1,192,085			1,187,191
		Commercial mortgage-backed securities			942,066			967,231			932,263			947,677
		Collateralized loan and debt obligations			195,914			197,893			92,519			94,552
		Asset-backed securities			378,442			381,206			351,192			353,256
		Total		$	4,936,755		$	5,017,663		$	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 June 30, 2014 and December 31, 2013, the Company had invested, net of capital returned, a total of $450.0 million and $440.9 million, respectively, in other investments. At June 30, 2014 and December 31, 2013, the carrying value of other investments was $648.6 million and $617.5 million, respectively. The following table summarizes the composition and redemption restrictions of other investments as of June 30, 2014 and December 31, 2013:
		30-Jun-14			Market Value			Unfunded Commitments			Ineligible for Redemption over next 12 months
		Alternative funds
			Hedge funds	$	420,656		$	-		$	44,553
			Private investment funds		67,137			69,709			67,137
		Total alternative funds			487,793			69,709			111,690
		Specialty funds
			High yield loan funds		113,453			-			-
			Convertible debt funds		47,396			-			-
		Total specialty funds			160,849			-			-
		Total other investments		$	648,642		$	69,709		$	111,690
		31-Dec-13			Market Value			Unfunded Commitments			Ineligible for 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 89.4% 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
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 and the change in the fair value of investment-related derivative financial instruments for the three and six months ended June 30, 2014 and 2013 is as follows:
			Three Months Ended						Six Months Ended
			June 30,						June 30,
			2014			2013			2014			2013
	Gross realized gains on investment sales	$	7,387		$	16,591		$	17,634		$	24,011
	Gross realized losses on investment sales		-5,319			-5,283			-11,303			-6,746
	Change in fair value of derivative financial instruments(1)		1,343			-936			1,952			-658
	Net realized and unrealized investment gains	$	3,411		$	10,372		$	8,283		$	16,607
	(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 June 30, 2014 and December 31, 2013 are as follows:
						Gross			Gross
			Amortized			Unrealized			Unrealized						Non-Credit
	30-Jun-14		Cost			Gains			Losses			Fair Value			OTTI (2)
	Fixed maturity investments
		U.S. government and agencies securities	$	558,408		$	7,759		$	-2,047		$	564,120		$	-
		U.S. state and municipal securities		32,578			249			-115			32,712			-
		Foreign government securities		230,217			2,405			-936			231,686			-
		Government guaranteed corporate securities		52,378			609			-			52,987			-
		Corporate securities		1,319,954			21,300			-1,665			1,339,589			-
		Residential mortgage-backed securities		1,202,234			27,040			-3,599			1,225,675			-3,959
		Commercial mortgage-backed securities		942,066			27,461			-2,296			967,231			-6
		Collateralized loan and debt obligations(1)		195,914			2,140			-161			197,893			-
		Asset-backed securities		378,442			3,125			-361			381,206			-153
	Total fixed maturity investments		$	4,912,191		$	92,088		$	-11,180		$	4,993,099		$	-4,118
	Short-term investments			24,564			9			-9			24,564			-
	Total fixed income investments		$	4,936,755		$	92,097		$	-11,189		$	5,017,663		$	-4,118
	Equity securities
		Equity investments	$	175,435		$	33,968		$	-571		$	208,832		$	-
		Emerging market debt funds		60,250			2,575			-			62,825			-
		Preferred equity investments		7,548			2,211			-5			9,754			-
		Short-term fixed income fund		6,230			2			-1			6,231			-
	Total equity securities		$	249,463		$	38,756		$	-577		$	287,642		$	-
-1	Balances include amounts related to collateralized debt obligations held with total fair values of $11.9 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 June 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.
							Gross			Gross
				Amortized			Unrealized			Unrealized						Non-Credit
		31-Dec-13		Cost			Gains			Losses			Fair Value			OTTI (2)
		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.
The following tables summarize, for all available for sale securities in an unrealized loss position at June 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
	30-Jun-14					Losses			Value			Losses			Value			Losses		Value
	Fixed maturity investments
		U.S. government and agencies
			securities		$	-44		$	26,863		$	-2,003		$	117,013		$	-2,047	$	143,876
		U.S. state and municipal
			securities			-41			4,829			-74			6,842			-115		11,671
		Foreign government securities				-660			58,447			-276			18,721			-936		77,168
		Corporate securities				-370			142,038			-1,295			103,889			-1,665		245,927
		Residential mortgage-backed
			securities			-155			31,998			-3,444			163,473			-3,599		195,471
		Commercial mortgage-backed
			securities			-436			53,792			-1,860			100,956			-2,296		154,748
		Collateralized loan and debt
			obligations			-51			60,408			-110			1,839			-161		62,247
		Asset-backed securities				-97			88,237			-264			24,218			-361		112,455
	Total fixed maturity investments				$	-1,854		$	466,612		$	-9,326		$	536,951		$	-11,180	$	1,003,563
	Short-term investments					-9			14,936			-			-			-9		14,936
	Total fixed income investments				$	-1,863		$	481,548		$	-9,326		$	536,951		$	-11,189	$	1,018,499
	Equity securities
		Equity investments			$	-467		$	11,368		$	-104		$	7,276		$	-571	$	18,644
		Preferred equity investments				-3			122			-2			200			-5		322
		Short-term fixed income fund				-1			2,899			-			-			-1		2,899
	Total equity securities				$	-471		$	14,389		$	-106		$	7,476		$	-577	$	21,865
As of June 30, 2014, 468 available for sale securities were in an unrealized loss position aggregating $11.8 million. Of those, 243 securities with aggregated unrealized losses of $9.4 million at June 30, 2014 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
	31-Dec-13					Losses(1)			Value			Losses(1)			Value			Losses(1)		Value
	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 six months ended June 30, 2014 and 2013 is as follows:
			Three months ended June 30,						Six months ended June 30,
			2014			2013			2014			2013
	Total other-than-temporary impairment losses	$	-198		$	-579		$	-309		$	-1,385
	Portion of loss recognized in other
	comprehensive income (loss)		-			-			-			-
	Net impairment losses recognized in earnings	$	-198		$	-579		$	-309		$	-1,385
3.       Investments, cont'd.
Of the $0.2 million (2013: $0.6 million) of OTTI losses recognized by the Company in the second 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 June 30, 2014 compared to December 31, 2013 was primarily due to a decrease in interest rates during the period. At June 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 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 June 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 six months ended June 30, 2014:
			Three months ended June 30,						Six months ended June 30,
			2014			2013			2014			2013
	Beginning balance		$	-1,520		$	-1,883		$	-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
	Addition for the amount related to the credit loss for
		which an other-than-temporary impairment was
		previously recognized		-			0			-			0
	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			79			114			112			231
	Ending balance		$	-1,441		$	-1,769		$	-1,441		$	-1,769
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 June 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	6 Months Ended
	Jun. 30, 2014
Fair Value Measurement	'
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.
	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 June 30, 2014.
	Transfers between levels are assumed to occur at the end of each period.
	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 June 30, 2014:
					Fair Value Measurements at June 30, 2014
								Quoted
								Prices in
								Active		Significant
								Markets for		Other		Significant
					Total at			Identical		Observable		Unobservable
					June 30,			Assets		Inputs		Inputs
					2014			(Level 1)		(Level 2)		(Level 3)
		Assets
		Fixed maturity investments
			U.S. government and agencies securities	$	564,120		$	15,995	$	548,125	$	-
			U.S. state and municipal securities		32,712			-		32,712		-
			Foreign government securities		231,686			-		231,686		-
			Government guaranteed corporate securities		52,987			-		52,987		-
			Corporate securities		1,339,589			-		1,338,871		718
			Residential mortgage-backed securities		1,225,675			-		1,222,760		2,915
			Commercial mortgage-backed securities		967,231			-		966,594		637
			Collateralized loan and debt obligations		197,893			-		195,667		2,226
			Asset-backed securities		381,206			-		378,187		3,019
		Total fixed maturity investments		$	4,993,099		$	15,995	$	4,967,589	$	9,515
		Equity securities
			Equity investments		208,832			147,659		61,173		-
			Emerging market debt funds		62,825			-		62,825		-
			Preferred equity investments		9,754			-		9,754		-
			Short-term fixed income fund		6,231			6,231		-		-
		Total equity securities		$	287,642		$	153,890	$	133,752	$	-
		Short-term investments			24,564			-		24,564		-
		Other investments			648,642			-		-		648,642
		Other assets (see Note 7)			79,888			-		68,896		10,992
		Total assets		$	6,033,835		$	169,885	$	5,194,801	$	669,149
		Liabilities
		Other liabilities (see Note 7)		$	27,434		$	-	$	17,150	$	10,284
		Debt			600,720			-		600,720		-
		Total liabilities		$	628,154		$	-	$	617,870	$	10,284
	During the three months ended June 30, 2014, $2.9 million of primarily residential mortgage-backed securities were transferred into Level 3 as no observable inputs were available, and $1.6 million of primarily commercial mortgage-backed securities were transferred out of Level 3 during the period as market activity for these securities increased and observable inputs became available.
	During the six months ended June 30, 2014, $5.0 million of primarily commercial and residential mortgage-backed securities were transferred into Level 3 as no observable inputs were available, and $1.9 million of primarily commercial mortgage-backed securities were transferred out of Level 3 as market activity for these securities increased and observable inputs became available. During the three and six months ended June 30, 2014, there were no transfers into or out of Level 1.
	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
								Quoted
								Prices in
								Active		Significant
								Markets for		Other		Significant
					Total at			Identical		Observable		Unobservable
					December 31,			Assets		Inputs		Inputs
					2013			(Level 1)		(Level 2)		(Level 3)
		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 11.1% and 10.9% of the Company's total available for sale investments, other investments and derivative instruments at June 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 six months ended June 30, 2014.
4.       Fair value measurement, cont'd.
Other assets and other liabilities measured at fair value include assets of $11.0 million (2013 - $14.0 million) and liabilities of $10.3 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 typically include the following, if applicable, dependent on contract requirements and commodity type:
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 impact 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 asset classified in Level 3 which is measured at fair value on a recurring basis at June 30, 2014:
			30-Jun-14
			Fair Value (Level 3)		Valuation Techniques		Unobservable Inputs	Low		High		Weighted Average or Actual
			(U.S. dollars in thousands, except for correlation and commodity curve)
	Net weather and energy related derivative asset	$	708		Historical Analysis and Simulation		Correlation		0		1	Actual
							Weather curve	$	-1,200	$	1,200	Actual
							Commodity curve	$	11.59	$	91.64	Actual
4.       Fair value measurement, cont'd.
There were no impairment losses on Level 3 securities recognized in earnings for the three and six months ended June 30, 2014 or 2013. 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 June 30, 2014 and 2013:
			Three Months Ended June 30, 2014
			Fixed maturity investments			Other investments		Other assets		Total assets		Other liabilities
	Level 3, beginning of period		$	8,985		$	621,914	$	8,532	$	639,431	$	-13,448
	Total equity income and realized gains included in
		earnings		36			16,286		-		16,322		-
	Total equity losses and losses included in earnings			-			-5,501		-		-5,501		-
	Total income included in other underwriting (loss) income			-			-		11,241		11,241		12,622
	Total loss included in other underwriting (loss)
		income		-			-		-11,722		-11,722		-12,177
	Change in unrealized gains included in other
		comprehensive income (loss)		89			-		-		89		-
	Change in unrealized losses included in other
		comprehensive income (loss)		-36			-		-		-36		-
	Purchases			-			21,867		-		21,867		-
	Issues			-			-		2,941		2,941		-5,883
	Sales			-856			-5,924		-		-6,780		-
	Settlements			-			-		-		-		8,602
	Transfers in to Level 3			2,886			-		-		2,886		-
	Transfers out of Level 3			-1,589			-		-		-1,589		-
	Level 3, end of period		$	9,515		$	648,642	$	10,992	$	669,149	$	-10,284
			Three Months Ended June 30, 2013
			Fixed maturity investments			Other investments		Other assets		Total assets		Other liabilities
	Level 3, beginning of period		$	9,814		$	554,715	$	6	$	564,535	$	-12
	Total equity income and realized gains included in
		earnings		43			16,419		-		16,462		-
	Total equity losses and losses included in earnings			-2			-9,639		-		-9,641		-
	Total income included in other underwriting (loss) income			-			-		-		-		12
	Total loss included in other underwriting (loss) income			-			-		-6		-6		-
	Change in unrealized gains included in other
		comprehensive income (loss)		243			-		-		243		-
	Change in unrealized losses included in other
		comprehensive income (loss)		-154			-		-		-154		-
	Purchases			-			23,424		-		23,424		-
	Sales			-2,276			-15,526		-		-17,802		-
	Transfers in to Level 3			383			-		-		383		-
	Transfers out of Level 3			-505			-		-		-505		-
	Level 3, end of period		$	7,546		$	569,393	$	-	$	576,939	$	-
The following table presents 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 six months ended June 30, 2014 and 2013:
			Six Months Ended June 30, 2014
			Fixed maturity investments			Other investments		Other assets		Total assets		Other 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		53			35,472		-		35,525		-
	Total equity losses and losses included in earnings			-26			-11,146		-		-11,172		-
	Total income included in other underwriting (loss) income			-			-		15,216		15,216		20,048
	Total loss included in other underwriting (loss) income			-			-		-18,610		-18,610		-16,953
	Change in unrealized gains included in other
		comprehensive income (loss)		200			-		-		200		-
	Change in unrealized losses included in other
		comprehensive income (loss)		-151			-		-		-151		-
	Purchases			-			26,541		-		26,541		-
	Issues			-			-		3,581		3,581		-7,163
	Sales			-1,040			-19,703		-		-20,743		-
	Settlements			-			-		-3,233		-3,233		13,353
	Transfers in to Level 3			5,003			-		-		5,003		-
	Transfers out of Level 3			-1,852			-		-		-1,852		-
	Level 3, end of period		$	9,515		$	648,642	$	10,992	$	669,149	$	-10,284
			Six Months Ended June 30, 2013
			Fixed maturity investments			Other investments		Other assets		Total assets		Other liabilities
	Level 3, beginning of period		$	8,497		$	517,546	$	882	$	526,925	$	-1,922
	Total equity income and realized gains included in
		earnings		48			41,902		-		41,950		-
	Total equity losses and losses included in earnings			-2			-12,063		-		-12,065		-
	Total income included in other underwriting (loss) income			-			-		-		-		2,354
	Total loss included in other underwriting (loss) income			-			-		-1,182		-1,182		-
	Change in unrealized gains included in other
		comprehensive income (loss)		327			-		-		327		-
	Change in unrealized losses included in other
		comprehensive income (loss)		-208			-		-		-208		-
	Purchases			-			45,414		-		45,414		-
	Issues			-			-		300		300		-432
	Sales			-4,202			-23,406		-		-27,608		-
	Transfers in to Level 3			3,647			-		-		3,647		-
	Transfers out of Level 3			-561			-		-		-561		-
	Level 3, end of period		$	7,546		$	569,393	$	-	$	576,939	$	-

Earnings_Per_Share

Earnings Per Share	6 Months Ended
	Jun. 30, 2014
Earnings Per Share	'
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 six months ended June 30, 2014 and 2013:
						Three Months Ended						Six Months Ended
						June 30,						June 30,
						2014			2013			2014			2013
		Numerator:
			Net income available to common and participating
				common shareholders	$	74,975		$	52,831		$	171,267		$	144,942
			Less amount allocated to participating
				common shareholders(1)		-2,212			-1,132			-4,988			-2,745
			Net income allocated to common shareholders		$	72,763		$	51,699		$	166,279		$	142,197
		Denominator:
			Weighted average shares – basic			43,350,911			42,621,301			43,265,200			42,526,686
			Share equivalents:
				Options		-			-			283			-
				Restricted share units		-			229			143			679
			Weighted average shares – diluted			43,350,911			42,621,530			43,265,626			42,527,365
		Basic earnings per common share			$	1.68		$	1.21		$	3.84		$	3.34
		Diluted earnings per common share			$	1.68		$	1.21		$	3.84		$	3.34
		(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 $0.46875 per Series B preferred share on May 21, 2014 (2013 - Series A: $0.484375, Series B: $0.46875). The Series A and Series B preferred share dividends were paid on June 16, 2014 to shareholders of record on June 2, 2014. Endurance Holdings also declared a dividend of $0.34 per common share on May 21, 2014 (2013 - $0.32). The dividend was paid on June 30, 2014 to shareholders of record on June 16, 2014.
				Three Months Ended						Six Months Ended
				June 30,						June 30,
				2014			2013			2014			2013
		Dividends declared per Series A preferred share		$	0.484375		$	0.484375		$	0.96875		$	0.96875
		Dividends declared per Series B preferred share		$	0.46875		$	0.46875		$	0.9375		$	0.9375
		Dividends declared per common share		$	0.34		$	0.32		$	0.68		$	0.64

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 2014
Accumulated Other Comprehensive Income	'
Accumulated Other Comprehensive Income	'
	6.       Accumulated other comprehensive income
	The following table presents the changes in accumulated other comprehensive income balances by component for the three months ended June 30, 2014 and 2013:
			For the Three Months Ended June 30, 2014
			Loss on cash flow hedge			Unrealized gains on available-for-sale securities		Foreign currency translation adjustments		Total
	Beginning balance		$	-1,832		$	69,330	$	21,861	$	89,359
		Other comprehensive income before reclassifications		-			39,676		8,998		48,674
		Amounts reclassified from accumulated other comprehensive income(1)		22			-2,017		-		-1,995
	Net current period other comprehensive income			22			37,659		8,998		46,679
	Ending balance		$	-1,810		$	106,989	$	30,859	$	136,038
	(1) All amounts are net of tax.
			For the Three Months Ended June 30, 2013
			Loss on cash flow hedge			Unrealized gains on available-for-sale securities		Foreign currency translation adjustments		Total
	Beginning balance		$	-1,928		$	136,885	$	2,482	$	137,439
		Other comprehensive loss before reclassifications		-			-96,457		219		-96,238
		Amounts reclassified from accumulated other comprehensive income(1)		29			-9,792		-		-9,763
	Net current period other comprehensive loss			29			-106,249		219		-106,001
	Ending balance		$	-1,899		$	30,636	$	2,701	$	31,438
	(1) All amounts are net of tax.
	The following table presents the changes in accumulated other comprehensive income balances by component for the six months ended June 30, 2014 and 2013:
			Six Months Ended June 30, 2014
			Gains and losses on cash flow hedges			Unrealized gains and losses on available-for-sale securities		Foreign currency translation adjustments		Total
	Beginning balance		$	-1,855		$	45,950	$	18,636	$	62,731
		Other comprehensive income before reclassifications		-			67,341		12,223		79,564
		Amounts reclassified from accumulated other comprehensive income(1)		45			-6,302		-		-6,257
	Net current period other comprehensive income			45			61,039		12,223		73,307
	Ending balance		$	-1,810		$	106,989	$	30,859	$	136,038
	(1) All amounts are net of tax.
			Six Months Ended June 30, 2013
			Gains and losses on cash flow hedges			Unrealized gains and losses on available-for-sale securities		Foreign currency translation adjustments		Total
	Beginning balance		$	-1,944		$	141,731	$	12,676	$	152,463
		Other comprehensive loss before reclassifications		-			-96,360		-9,975		-106,335
		Amounts reclassified from accumulated other comprehensive income(1)		45			-14,735		-		-14,690
	Net current period other comprehensive loss			45			-111,095		-9,975		-121,025
	Ending balance		$	-1,899		$	30,636	$	2,701	$	31,438
	(1) All amounts are net of tax.
	6.       Accumulated other comprehensive income, cont'd.
	The following table presents the significant items reclassified out of accumulated other comprehensive income during the three months ended June 30, 2014 and 2013:
		Three Months Ended June 30, 2014
		Details about accumulated other comprehensive income components			Amount reclassified from accumulated other comprehensive income		Affected line item in the Unaudited Condensed Consolidated Statements of Income and Comprehensive Income (Loss)
		Loss on cash flow hedge - Debt		$	22		Interest expense
					22		Total before income taxes
					-		Income tax expense
				$	22		Total net of income taxes
		Unrealized gains on available-for-sale securities		$	-2,068		Net realized and unrealized investment gains
					198		Net impairment losses recognized in earnings
					-1,870		Total before income taxes
					-147		Income tax benefit
				$	-2,017		Total net of income taxes
		Three Months Ended June 30, 2013
		Details about accumulated other comprehensive income components			Amount reclassified from accumulated other comprehensive income		Affected line item in the Unaudited Condensed Consolidated Statements of Income and Comprehensive Income (Loss)
		Loss on cash flow hedge - Debt		$	29		Interest expense
					29		Total before income taxes
					-		Income tax expense
				$	29		Total net of income taxes
		Unrealized gains on available-for-sale securities		$	-11,308		Net realized and unrealized investment gains
					579		Net impairment losses recognized in earnings
					-10,729		Total before income taxes
					937		Income tax expense
				$	-9,792		Total net of income taxes
	The following table presents the significant items reclassified out of accumulated other comprehensive income during the six months ended June 30, 2014 and 2013:
		Six Months Ended June 30, 2014
		Details about accumulated other comprehensive income components			Amount reclassified from accumulated other comprehensive income		Affected line item in the Unaudited Condensed Consolidated Statements of Income and Comprehensive Income (Loss)
		Gains and losses on cash flow hedges - Debt		$	45		Interest expense
				45		Total before income taxes
				-		Income tax expense
			$	45		Total net of income taxes
	Unrealized (gains) losses on available-for-sale securities		$	-6,331		Net realized and unrealized investment gains
				309		Net impairment losses recognized in earnings
				-6,022		Total before income taxes
				-280		Income tax benefit
			$	-6,302		Total net of income taxes
	Six Months Ended June 30, 2013
	Details about accumulated other comprehensive income components			Amount reclassified from accumulated other comprehensive income		Affected line item in the Unaudited Condensed Consolidated Statements of Income and Comprehensive Income (Loss)
	Gains and losses on cash flow hedges - Debt		$	45		Interest expense
				45		Total before income taxes
				-		Income tax expense
			$	45		Total net of income taxes
	Unrealized gains on available-for-sale securities		$	-17,265		Net realized and unrealized investment gains
				1,385		Net impairment losses recognized in earnings
				-15,880		Total before income taxes
				1,145		Income tax expense
			$	-14,735		Total net of income taxes

Derivatives

Derivatives	6 Months Ended
	Jun. 30, 2014
Derivatives	'
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 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, net foreign exchange losses and other underwriting (loss) income in the Condensed Consolidated Statements of Income and Comprehensive Income (Loss).
	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.
	Commodity Futures and Options - to economically hedge certain underwriting risks.
	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.
	The fair values and the related notional values of derivatives at June 30, 2014 and December 31, 2013 are noted below.
				30-Jun-14				31-Dec-13
						Notional				Notional
				Fair		Principal		Fair		Principal
				Value		Amount		Value		Amount
		Derivatives recorded in other assets
			Foreign exchange forward contracts	$	59	$	16,763	$	251	$	19,269
			Credit default swaps		22		1,815		-		-
			Interest rate swaps		-		-		124		16,100
			Interest rate swaptions		-		23,238		39		24,338
			TBAs		68,815		67,000		93,820		93,840
			Energy and weather contracts		10,992		42,965		14,038		53,986
			Total recorded in other assets	$	79,888			$	108,272
		Derivatives recorded in other liabilities
			Foreign exchange forward contracts	$	201	$	23,632	$	172	$	15,861
			Interest rate swaps		670		22,556		933		12,193
			Interest rate swaptions		-		23,238		543		361,455
			Interest rate futures		-		-		17		103,935
			TBAs		16,279		16,000		28,218		28,000
			Energy and weather contracts		10,284		65,800		19,569		66,113
			Total recorded in other liabilities	$	27,434			$	49,452
			Net derivative asset	$	52,454			$	58,820
	At June 30, 2014, the Company's derivative assets of $79.9 million (December 31, 2013 - $108.3 million) and liabilities of $27.4 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 June 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.
	7.       Derivatives, cont'd.
	The gains and losses on the Condensed Consolidated Statements of Income and Comprehensive Income (Loss) for derivatives for the three and six months ended June 30, 2014 and 2013 were as follows:
				Three Months Ended				Six Months Ended
				June 30,				June 30,
				2014		2013		2014		2013
		Total included in net foreign exchange losses from foreign
			exchange forward contracts	$	-172	$	169	$	-399	$	330
			Futures contracts	$	115	$	-47	$	135	$	-47
			Credit default swaps		14		114		14		116
			Interest rate swaps		-316		-279		-1,081		-161
			Interest rate swaptions		-1		-276		428		-101
			TBAs		1,531		-448		2,456		-465
		Total included in net realized and unrealized investment gains		$	1,343	$	-936	$	1,952	$	-658
		Total included in other underwriting (loss) income from energy
			and weather contracts	$	-40	$	6	$	-299	$	1,172
		Total gains (losses) from derivatives		$	1,131	$	-761	$	1,254	$	844

StockBased_Employee_Compensati

Stock-Based Employee Compensation And Other Stock Plans	6 Months Ended
	Jun. 30, 2014
Stock-Based Employee Compensation And Other Stock Plans	'
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 or expired during the quarter ended June 30, 2014. During the three months ended June 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 three months ended June 30, 2013. During the three months ended June 30, 2014, 15,000 (2013 - 12,501) options were exercised. During the three months ended June 30, 2014, 160,000 (2013 - 160,000) options vested. The total intrinsic value of options exercised during the quarter ended June 30, 2014 was $0.3 million (2013 - $0.3 million). The Company received proceeds of $0.5 million (2013 - $0.3 million) from the exercise of options during the quarter ended June 30, 2014. The Company issued new ordinary shares in connection with the exercise of the above options. For the quarter ended June 30, 2014, compensation costs recognized in earnings for all options totaled $0.9 million (2013 - $2.4 million). At June 30, 2014, compensation costs not yet recognized related to unvested stock options was $3.7 million (2013 - $7.8 million).
	No options were granted or expired during the six months ended June 30, 2014. During the six months ended June 30, 2013, 800,000 options were granted with a weighted average grant date fair value of $10.2 million. No options expired during the six months ended June 30, 2013. During the six months ended June 30, 2014, 15,000 (2013 - 24,501) options were exercised. During the six months ended June 30, 2014, 160,000 (2013 - 160,000) options vested. The total intrinsic value of options exercised during the six months ended June 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 six months ended June 30, 2014. The Company issued new ordinary shares in connection with the exercise of the above options. For the six months ended June 30, 2014, compensation costs recognized in earnings for all options totaled $2.0 million (2013 - $2.4 million).
	During the quarter ended June 30, 2014, the Company granted an aggregate of 97,646 (2013 – 727,271) restricted shares with weighted average grant date fair values of $5.1 million (2013 - $35.1 million). During the quarter ended June 30, 2014, the aggregate fair value of restricted shares and restricted share units that vested was $8.3 million (2013 - $7.8 million). For the quarter ended June 30, 2014, compensation costs recognized in earnings for all restricted shares and restricted share units were $6.6 million (2013 - $8.8 million). At June 30, 2014, compensation costs not yet recognized related to unvested restricted shares and restricted share units was $31.8 million (2013 - $38.5 million).
	During the six months ended June 30, 2014, the Company granted an aggregate of 433,417 (2013 – 1,070,655) restricted shares and restricted share units with weighted average grant date fair values of $22.7 million (2013 - $50.3 million). During the six months ended June 30, 2014, the aggregate fair value of restricted shares and restricted share units that vested was $18.5 million (2013 - $16.9 million). For the six months ended June 30, 2014, compensation costs recognized in earnings for all restricted shares and restricted share units were $15.8 million (2013 - $13.5 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 June 30, 2014, total expenses related to the Company's Employee Share Purchase Plan were approximately $55,000 (2013 - $44,000) and $109,000 (2013 - $82,000) for the six months ended June 30, 2014.

Segment_Reporting

Segment Reporting	6 Months Ended
	Jun. 30, 2014
Segment Reporting	'
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.
	The following table provides a summary of segment revenues, results and reserves for losses and loss expenses for the three months ended June 30, 2014:
					Three Months Ended June 30, 2014
						Insurance			Reinsurance				Total
			Revenues
				Gross premiums written		$	321,526		$	367,899			$	689,425
				Ceded premiums written			-142,488			-35,510				-177,998
				Net premiums written			179,038			332,389				511,427
				Net premiums earned			218,563			262,975				481,538
				Other underwriting loss			-			-4,824				-4,824
							218,563			258,151				476,714
			Expenses
				Net losses and loss expenses			149,567			109,629				259,196
				Acquisition expenses			15,128			63,473				78,601
				General and administrative expenses			47,237			39,218				86,455
							211,932			212,320				424,252
			Underwriting income			$	6,631		$	45,831			$	52,462
			Net loss ratio				68.5	%		41.7	%			53.8	%
			Acquisition expense ratio				6.9	%		24.1	%			16.3	%
			General and administrative expense ratio				21.6	%		14.9	%			18	%
			Combined ratio				97	%		80.7	%			88.1	%
			Reserve for losses and loss expenses			$	2,143,921		$	1,819,472			$	3,963,393
	The following table provides a summary of segment revenues, results and reserves for losses and loss expenses for the three months ended June 30, 2013:
					Three Months Ended June 30, 2013
							Insurance			Reinsurance				Total
			Revenues
				Gross premiums written		$	276,941		$	295,769			$	572,710
				Ceded premiums written			-85,439			-22,650				-108,089
				Net premiums written			191,502			273,119				464,621
				Net premiums earned			267,878			275,457				543,335
				Other underwriting income			-			888				888
							267,878			276,345				544,223
			Expenses
				Net losses and loss expenses			215,844			143,214				359,058
				Acquisition expenses			14,968			56,900				71,868
				General and administrative expenses			43,524			37,835				81,359
							274,336			237,949				512,285
			Underwriting (loss) income			$	-6,458		$	38,396			$	31,938
			Net loss ratio				80.6	%		52	%			66.1	%
			Acquisition expense ratio				5.6	%		20.7	%			13.2	%
			General and administrative expense ratio				16.2	%		13.7	%			15	%
			Combined ratio				102.4	%		86.4	%			94.3	%
			Reserve for losses and loss expenses			$	2,242,894		$	1,902,687			$	4,145,581
	The following table reconciles total segment results to income before income taxes for the three months ended June 30, 2014 and 2013:
				Three Months Ended
				June 30,
					2014			2013
			Total underwriting income	$	52,462		$	31,938
			Net investment income		39,302			32,468
			Net foreign exchange losses		-319			-3,368
		Net realized and unrealized investment gains		3,411			10,372
		Net impairment losses recognized in earnings		-198			-579
		Amortization of intangibles		-1,623			-1,625
		Interest expense		-9,732			-9,052
		Income before income taxes	$	83,303		$	60,154
The following table provides gross and net premiums written by line of business for the three months ended June 30, 2014 and 2013:
				Gross			Net		Gross			Net
				premiums			premiums		premiums			premiums
				written			written		written			written
	Business Segment			2014			2014		2013			2013
	Insurance
		Agriculture	$	80,540		$	45,826	$	131,633		$	84,537
		Casualty and other specialty		146,728			89,765		87,614			63,373
		Professional lines		74,650			29,846		38,296			27,788
		Property		19,608			13,601		19,398			15,804
	Total Insurance			321,526			179,038		276,941			191,502
	Reinsurance
		Catastrophe		158,372			123,411		155,431			138,041
		Property		42,887			42,886		48,384			44,516
		Casualty		30,875			30,868		54,417			54,419
		Professional lines		84,117			84,117		12,528			12,528
		Specialty		51,648			51,107		25,009			23,615
	Total Reinsurance			367,899			332,389		295,769			273,119
	Total		$	689,425		$	511,427	$	572,710		$	464,621
The following table provides a summary of the segment revenues and results for the six months ended June 30, 2014:
				Six Months Ended June 30, 2014
						Insurance			Reinsurance				Total
		Revenues
			Gross premiums written		$	973,802		$	873,138			$	1,846,940
			Ceded premiums written			-451,737			-85,071				-536,808
			Net premiums written			522,065			788,067				1,310,132
			Net premiums earned			362,584			515,220				877,804
			Other underwriting loss			-			-6,062				-6,062
						362,584			509,158				871,742
		Expenses
			Net losses and loss expenses			238,100			197,992				436,092
			Acquisition expenses			27,389			123,369				150,758
			General and administrative expenses			88,973			70,688				159,661
						354,462			392,049				746,511
		Underwriting income			$	8,122		$	117,109			$	125,231
		Net loss ratio				65.7	%		38.5	%			49.6	%
		Acquisition expense ratio				7.6	%		23.9	%			17.2	%
		General and administrative expense ratio				24.5	%		13.7	%			18.2	%
		Combined ratio				97.8	%		76.1	%			85	%
The following table provides a summary of the segment revenues and results for the six months ended June 30, 2013:
				Six Months Ended June 30, 2013
						Insurance			Reinsurance				Total
		Revenues
			Gross premiums written		$	929,884		$	820,188			$	1,750,072
			Ceded premiums written			-333,688			-42,848				-376,536
			Net premiums written			596,196			777,340				1,373,536
			Net premiums earned			419,030			544,422				963,452
			Other underwriting income			-			1,637				1,637
						419,030			546,059				965,089
		Expenses
			Net losses and loss expenses			315,308			262,720				578,028
			Acquisition expenses			29,584			113,920				143,504
			General and administrative expenses			79,151			68,686				147,837
						424,043			445,326				869,369
		Underwriting (loss) income			$	-5,013		$	100,733			$	95,720
		Net loss ratio				75.2	%		48.3	%			60	%
		Acquisition expense ratio				7.1	%		20.9	%			14.9	%
		General and administrative expense ratio				18.9	%		12.6	%			15.3	%
		Combined ratio				101.2	%		81.8	%			90.2	%
The following table reconciles total segment results to income before income taxes for the six months ended June 30, 2014 and 2013, respectively:
		Six Months Ended
		June 30,
			2014			2013
	Total underwriting income	$	125,231		$	95,720
	Net investment income		80,292			81,773
	Net foreign exchange losses		-3,283			-6,295
	Net realized and unrealized investment gains		8,283			16,607
	Net impairment losses recognized in earnings		-309			-1,385
	Amortization of intangibles		-3,240			-3,726
	Interest expense		-18,783			-18,090
	Income before income taxes	$	188,191		$	164,604
The following table provides gross and net premiums written by line of business for the six months ended June 30, 2014 and 2013:
				Gross			Net		Gross			Net
				premiums			premiums		premiums			premiums
				written			written		written			written
	Business Segment			2014			2014		2013			2013
	Insurance
		Agriculture	$	608,434		$	327,471	$	696,107		$	425,667
		Casualty and other specialty		221,623			131,486		144,081			106,634
		Professional lines		113,430			44,416		59,260			41,991
		Property		30,315			18,692		30,436			21,904
	Total Insurance			973,802			522,065		929,884			596,196
	Reinsurance
		Catastrophe		285,020			202,374		303,297			269,439
		Property		209,300			209,208		196,795			192,927
		Casualty		115,857			114,260		183,809			182,382
		Professional lines		109,736			109,736		24,835			24,835
		Specialty		153,225			152,489		111,452			107,757
	Total Reinsurance			873,138			788,067		820,188			777,340
	Total		$	1,846,940		$	1,310,132	$	1,750,072		$	1,373,536

Commitments_And_Contingencies

Commitments And Contingencies	6 Months Ended
	Jun. 30, 2014
Commitments And Contingencies	'
Commitments And Contingencies	'
	10. Commitments and contingencies
	Concentrations of credit risk. The Company's reinsurance recoverables on paid and unpaid losses at June 30, 2014 and December 31, 2013 amounted to $751.8 million and $758.0 million, respectively. At June 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 June 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 six months ended June 30, 2014 and 2013, respectively:
		Broker	2014		2013
		Marsh & McLennan Companies, Inc.	22.1	%	19.5	%
		Aon Benfield	16	%	15.3	%
		Willis Companies	11.8	%	9.8	%
		Total of largest brokers	49.9	%	44.6	%
	10. Commitments and contingencies, cont'd.
	Letters of credit. As of June 30, 2014, the Company had issued letters of credit of $216.8 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 June 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.
	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 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 ten 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).
	10. Commitments and contingencies, cont'd.
	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.
	Investment commitments. As of June 30, 2014 and December 31, 2013, the Company had pledged cash and cash equivalents and fixed maturity investments of $128.7 million and $146.1 million, respectively, in favor of certain ceding companies to collateralize obligations. As of June 30, 2014 and December 31, 2013, the Company had also pledged $250.2 million and $302.7 million of its cash and fixed maturity investments as required to meet collateral obligations for $216.8 million and $260.3 million, respectively, in letters of credit outstanding under its credit facility and LOC Agreement. In addition, as of June 30, 2014 and December 31, 2013, cash and fixed maturity investments with fair values of $274.6 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 June 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.
	10. Commitments and contingencies, cont'd.
	Operating leases. The Company leases office space and office equipment under operating leases. Future minimum lease commitments at June 30, 2014 are as follows:
		Twelve months ended June 30,	Amount
		2015	$	15,984
		2016		14,379
		2017		12,157
		2018		11,882
		2019		10,422
		2020 and thereafter		39,173
			$	103,997
	Total net lease expense under operating leases for the six months ended June 30, 2014 was $8.2 million (2013 – $7.1 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	6 Months Ended
	Jun. 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 June 30, 2014, there were no borrowings under this facility and letters of credit outstanding under the Credit Facility were $216.8 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 contains certain amendments to the Credit Facility and the Security Agreement to facilitate the proposed acquisition of Aspen and to change certain other provisions of the Credit Facility by, among other things, increasing the maximum permitted leverage ratio (calculated as provided in the Credit Facility) from 0.35:1.00 to 0.40:1.00 until the last day of the third full fiscal quarter following the consummation of any acquisition of Aspen, increasing the permitted amount of letters of credit and unsecured indebtedness and increasing the threshold amounts for cross-defaults, judgment defaults, and defaults under the Employee Retirement Income Security Act of 1974, as amended. Certain of the amendments would have become effective only upon consummation of an acquisition of Aspen.
	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. As of June 30, 2014, there were no borrowings under the Bridge Facility. Upon the termination by the Company of its offer to acquire Aspen, the Bridge Facility expired pursuant to its terms.

Subsequent_Event

Subsequent Event	6 Months Ended
	Jun. 30, 2014
Subsequent Events [Abstract]	'
Subsequent Events [Text Block]	'
	12. Subsequent event
	On July 30, 2014, the Company terminated its offer to acquire Aspen. Upon the termination of the offer to acquire Aspen, the Bridge Facility expired pursuant to its terms.

Summary_Of_Significant_Account1

Summary Of Significant Accounting Policies (Policy)	6 Months Ended
	Jun. 30, 2014
Summary Of Significant Accounting Policies	'
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)	6 Months Ended
	Jun. 30, 2014
Investments	'
Other Investments	'
	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.”
Variable Interest Entities	'
	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 June 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.
Gain Loss On Investments	'
	Realized and unrealized investment gains and losses are recognized in earnings using the first in, first out method.

Fair_Value_Measurement_Policy

Fair Value Measurement (Policy)	6 Months Ended
	Jun. 30, 2014
Fair Value Measurement	'
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.
	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 June 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)	6 Months Ended
	Jun. 30, 2014
Earnings Per Share	'
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)	6 Months Ended
	Jun. 30, 2014
Derivatives	'
Accounting policy for derivativess	'
	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 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, net foreign exchange losses and other underwriting (loss) income in the Condensed Consolidated Statements of Income and Comprehensive Income (Loss).
	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.
	Commodity Futures and Options - to economically hedge certain underwriting risks.
	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.

Segment_Reporting_Policy

Segment Reporting (Policy)	6 Months Ended
	Jun. 30, 2014
Segment Reporting	'
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)	6 Months Ended
	Jun. 30, 2014
Investments	'
Composition Of Net Investment Income	'
				Three Months Ended June 30,						Six Months Ended June 30,
					2014			2013			2014			2013
			Available for sale investments	$	31,619		$	28,666		$	61,946		$	58,147
			Other investments		10,785			6,780			24,327			29,839
			Cash and cash equivalents		511			840			1,297			1,291
				$	42,915		$	36,286		$	87,570		$	89,277
			Investment expenses		-3,613			-3,818			-7,278			-7,504
			Net investment income	$	39,302		$	32,468		$	80,292		$	81,773
Composition of the Investment Portfolio by Investment Type	'
					30-Jun-14						31-Dec-13
			Type of Investment		Fair Value		Percentage				Fair Value		Percentage
			Fixed maturity investments	$	4,993,099		76.2	%		$	4,823,964		74.2	%
			Cash and cash equivalents(1)		595,910		9.1	%			771,714		11.9	%
			Other investments(2)		648,642		9.9	%			617,478		9.5	%
			Short-term investments		24,564		0.4	%			35,028		0.5	%
			Equity securities		287,642		4.4	%			252,466		3.9	%
			Total	$	6,549,857		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-Jun-14						31-Dec-13
			Ratings(1)		Fair Value		Percentage				Fair Value		Percentage
			U.S. government and agencies securities	$	564,120		11.2	%		$	769,343		15.8	%
			AAA / Aaa		1,137,895		22.7	%			972,820		20	%
			AA / Aa		1,782,465		35.5	%			1,771,156		36.5	%
			A / A		999,084		19.9	%			895,549		18.4	%
			BBB		421,356		8.4	%			363,722		7.5	%
			Below BBB		99,558		2	%			66,791		1.4	%
			Not rated		13,185		0.3	%			19,611		0.4	%
			Total	$	5,017,663		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-Jun-14						31-Dec-13
					Amortized						Amortized
					Cost			Fair Value			Cost			Fair Value
		Due within one year		$	147,587		$	148,630		$	144,814		$	145,653
		Due after one year through five years			1,638,278			1,653,175			1,808,001			1,815,240
		Due after five years through ten years			384,738			393,528			290,391			288,486
		Due after ten years			47,496			50,325			26,344			26,937
		Residential mortgage-backed securities			1,202,234			1,225,675			1,192,085			1,187,191
		Commercial mortgage-backed securities			942,066			967,231			932,263			947,677
		Collateralized loan and debt obligations			195,914			197,893			92,519			94,552
		Asset-backed securities			378,442			381,206			351,192			353,256
		Total		$	4,936,755		$	5,017,663		$	4,837,609		$	4,858,992
Other Investments	'
		30-Jun-14			Market Value			Unfunded Commitments			Ineligible for Redemption over next 12 months
		Alternative funds
			Hedge funds	$	420,656		$	-		$	44,553
			Private investment funds		67,137			69,709			67,137
		Total alternative funds			487,793			69,709			111,690
		Specialty funds
			High yield loan funds		113,453			-			-
			Convertible debt funds		47,396			-			-
		Total specialty funds			160,849			-			-
		Total other investments		$	648,642		$	69,709		$	111,690
		31-Dec-13			Market Value			Unfunded Commitments			Ineligible for 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	'
				Three Months Ended						Six Months Ended
				June 30,						June 30,
				2014			2013			2014			2013
		Gross realized gains on investment sales	$	7,387		$	16,591		$	17,634		$	24,011
		Gross realized losses on investment sales		-5,319			-5,283			-11,303			-6,746
		Change in fair value of derivative financial instruments(1)		1,343			-936			1,952			-658
		Net realized and unrealized investment gains	$	3,411		$	10,372		$	8,283		$	16,607
		(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	'
							Gross			Gross
				Amortized			Unrealized			Unrealized						Non-Credit
		30-Jun-14		Cost			Gains			Losses			Fair Value			OTTI (2)
		Fixed maturity investments
			U.S. government and agencies securities	$	558,408		$	7,759		$	-2,047		$	564,120		$	-
			U.S. state and municipal securities		32,578			249			-115			32,712			-
			Foreign government securities		230,217			2,405			-936			231,686			-
			Government guaranteed corporate securities		52,378			609			-			52,987			-
			Corporate securities		1,319,954			21,300			-1,665			1,339,589			-
			Residential mortgage-backed securities		1,202,234			27,040			-3,599			1,225,675			-3,959
			Commercial mortgage-backed securities		942,066			27,461			-2,296			967,231			-6
			Collateralized loan and debt obligations(1)		195,914			2,140			-161			197,893			-
			Asset-backed securities		378,442			3,125			-361			381,206			-153
		Total fixed maturity investments		$	4,912,191		$	92,088		$	-11,180		$	4,993,099		$	-4,118
		Short-term investments			24,564			9			-9			24,564			-
		Total fixed income investments		$	4,936,755		$	92,097		$	-11,189		$	5,017,663		$	-4,118
		Equity securities
			Equity investments	$	175,435		$	33,968		$	-571		$	208,832		$	-
			Emerging market debt funds		60,250			2,575			-			62,825			-
			Preferred equity investments		7,548			2,211			-5			9,754			-
			Short-term fixed income fund		6,230			2			-1			6,231			-
		Total equity securities		$	249,463		$	38,756		$	-577		$	287,642		$	-
	-1	Balances include amounts related to collateralized debt obligations held with total fair values of $11.9 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 June 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.
								Gross			Gross
					Amortized			Unrealized			Unrealized						Non-Credit
			31-Dec-13		Cost			Gains			Losses			Fair Value			OTTI (2)
			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.
Available For Sale Securities In An Unrealized Loss Position	'
							Less than 12 months						12 months or greater						Total
							Unrealized			Fair			Unrealized			Fair			Unrealized		Fair
		30-Jun-14					Losses			Value			Losses			Value			Losses		Value
		Fixed maturity investments
			U.S. government and agencies
				securities		$	-44		$	26,863		$	-2,003		$	117,013		$	-2,047	$	143,876
			U.S. state and municipal
				securities			-41			4,829			-74			6,842			-115		11,671
			Foreign government securities				-660			58,447			-276			18,721			-936		77,168
			Corporate securities				-370			142,038			-1,295			103,889			-1,665		245,927
			Residential mortgage-backed
				securities			-155			31,998			-3,444			163,473			-3,599		195,471
			Commercial mortgage-backed
				securities			-436			53,792			-1,860			100,956			-2,296		154,748
			Collateralized loan and debt
				obligations			-51			60,408			-110			1,839			-161		62,247
			Asset-backed securities				-97			88,237			-264			24,218			-361		112,455
		Total fixed maturity investments				$	-1,854		$	466,612		$	-9,326		$	536,951		$	-11,180	$	1,003,563
		Short-term investments					-9			14,936			-			-			-9		14,936
		Total fixed income investments				$	-1,863		$	481,548		$	-9,326		$	536,951		$	-11,189	$	1,018,499
		Equity securities
			Equity investments			$	-467		$	11,368		$	-104		$	7,276		$	-571	$	18,644
			Preferred equity investments				-3			122			-2			200			-5		322
			Short-term fixed income fund				-1			2,899			-			-			-1		2,899
		Total equity securities				$	-471		$	14,389		$	-106		$	7,476		$	-577	$	21,865
	3	Investments, cont’d.
							Less than 12 months						12 months or greater						Total
							Unrealized			Fair			Unrealized			Fair			Unrealized		Fair
		31-Dec-13					Losses(1)			Value			Losses(1)			Value			Losses(1)		Value
		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 June 30,						Six months ended June 30,
				2014			2013			2014			2013
		Total other-than-temporary impairment losses	$	-198		$	-579		$	-309		$	-1,385
		Portion of loss recognized in other
		comprehensive income (loss)		-			-			-			-
		Net impairment losses recognized in earnings	$	-198		$	-579		$	-309		$	-1,385
Credit Losses Recognized For Available For Sale Investments In Earnings, OTTI Loss Was Recognized In Accumulated Other Comprehensive Income	'
				Three months ended June 30,						Six months ended June 30,
				2014			2013			2014			2013
		Beginning balance		$	-1,520		$	-1,883		$	-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
		Addition for the amount related to the credit loss for
			which an other-than-temporary impairment was
			previously recognized		-			0			-			0
		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			79			114			112			231
		Ending balance		$	-1,441		$	-1,769		$	-1,441		$	-1,769

Fair_Value_Measurement_Tables

Fair Value Measurement (Tables)	6 Months Ended
	Jun. 30, 2014
Fair Value Measurement	'
Schedule Of Available For Sale Investments, Other Investments, Derivative Instruments And Debt Measured On A Recurring Basis	'
					Fair Value Measurements at June 30, 2014
								Quoted
								Prices in
								Active		Significant
								Markets for		Other		Significant
					Total at			Identical		Observable		Unobservable
					June 30,			Assets		Inputs		Inputs
					2014			(Level 1)		(Level 2)		(Level 3)
		Assets
		Fixed maturity investments
			U.S. government and agencies securities	$	564,120		$	15,995	$	548,125	$	-
			U.S. state and municipal securities		32,712			-		32,712		-
			Foreign government securities		231,686			-		231,686		-
			Government guaranteed corporate securities		52,987			-		52,987		-
			Corporate securities		1,339,589			-		1,338,871		718
			Residential mortgage-backed securities		1,225,675			-		1,222,760		2,915
			Commercial mortgage-backed securities		967,231			-		966,594		637
			Collateralized loan and debt obligations		197,893			-		195,667		2,226
			Asset-backed securities		381,206			-		378,187		3,019
		Total fixed maturity investments		$	4,993,099		$	15,995	$	4,967,589	$	9,515
		Equity securities
			Equity investments		208,832			147,659		61,173		-
			Emerging market debt funds		62,825			-		62,825		-
			Preferred equity investments		9,754			-		9,754		-
			Short-term fixed income fund		6,231			6,231		-		-
		Total equity securities		$	287,642		$	153,890	$	133,752	$	-
		Short-term investments			24,564			-		24,564		-
		Other investments			648,642			-		-		648,642
		Other assets (see Note 7)			79,888			-		68,896		10,992
		Total assets		$	6,033,835		$	169,885	$	5,194,801	$	669,149
		Liabilities
		Other liabilities (see Note 7)		$	27,434		$	-	$	17,150	$	10,284
		Debt			600,720			-		600,720		-
		Total liabilities		$	628,154		$	-	$	617,870	$	10,284
					Fair Value Measurements at December 31, 2013
								Quoted
								Prices in
								Active		Significant
								Markets for		Other		Significant
					Total at			Identical		Observable		Unobservable
					December 31,			Assets		Inputs		Inputs
					2013			(Level 1)		(Level 2)		(Level 3)
		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
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 June 30, 2014
				Fixed maturity investments			Other investments		Other assets		Total assets		Other liabilities
		Level 3, beginning of period		$	8,985		$	621,914	$	8,532	$	639,431	$	-13,448
		Total equity income and realized gains included in
			earnings		36			16,286		-		16,322		-
		Total equity losses and losses included in earnings			-			-5,501		-		-5,501		-
		Total income included in other underwriting (loss) income			-			-		11,241		11,241		12,622
		Total loss included in other underwriting (loss)
			income		-			-		-11,722		-11,722		-12,177
		Change in unrealized gains included in other
			comprehensive income (loss)		89			-		-		89		-
		Change in unrealized losses included in other
			comprehensive income (loss)		-36			-		-		-36		-
		Purchases			-			21,867		-		21,867		-
		Issues			-			-		2,941		2,941		-5,883
		Sales			-856			-5,924		-		-6,780		-
		Settlements			-			-		-		-		8,602
		Transfers in to Level 3			2,886			-		-		2,886		-
		Transfers out of Level 3			-1,589			-		-		-1,589		-
		Level 3, end of period		$	9,515		$	648,642	$	10,992	$	669,149	$	-10,284
				Three Months Ended June 30, 2013
				Fixed maturity investments			Other investments		Other assets		Total assets		Other liabilities
		Level 3, beginning of period		$	9,814		$	554,715	$	6	$	564,535	$	-12
		Total equity income and realized gains included in
			earnings		43			16,419		-		16,462		-
		Total equity losses and losses included in earnings			-2			-9,639		-		-9,641		-
		Total income included in other underwriting (loss) income			-			-		-		-		12
		Total loss included in other underwriting (loss) income			-			-		-6		-6		-
		Change in unrealized gains included in other
			comprehensive income (loss)		243			-		-		243		-
		Change in unrealized losses included in other
			comprehensive income (loss)		-154			-		-		-154		-
		Purchases			-			23,424		-		23,424		-
		Sales			-2,276			-15,526		-		-17,802		-
		Transfers in to Level 3			383			-		-		383		-
		Transfers out of Level 3			-505			-		-		-505		-
		Level 3, end of period		$	7,546		$	569,393	$	-	$	576,939	$	-
				Six Months Ended June 30, 2014
				Fixed maturity investments			Other investments		Other assets		Total assets		Other 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		53			35,472		-		35,525		-
		Total equity losses and losses included in earnings			-26			-11,146		-		-11,172		-
		Total income included in other underwriting (loss) income			-			-		15,216		15,216		20,048
		Total loss included in other underwriting (loss) income			-			-		-18,610		-18,610		-16,953
		Change in unrealized gains included in other
			comprehensive income (loss)		200			-		-		200		-
		Change in unrealized losses included in other
			comprehensive income (loss)		-151			-		-		-151		-
		Purchases			-			26,541		-		26,541		-
		Issues			-			-		3,581		3,581		-7,163
		Sales			-1,040			-19,703		-		-20,743		-
		Settlements			-			-		-3,233		-3,233		13,353
		Transfers in to Level 3			5,003			-		-		5,003		-
		Transfers out of Level 3			-1,852			-		-		-1,852		-
		Level 3, end of period		$	9,515		$	648,642	$	10,992	$	669,149	$	-10,284
				Six Months Ended June 30, 2013
				Fixed maturity investments			Other investments		Other assets		Total assets		Other liabilities
		Level 3, beginning of period		$	8,497		$	517,546	$	882	$	526,925	$	-1,922
		Total equity income and realized gains included in
			earnings		48			41,902		-		41,950		-
		Total equity losses and losses included in earnings			-2			-12,063		-		-12,065		-
		Total income included in other underwriting (loss) income			-			-		-		-		2,354
	Total loss included in other underwriting (loss) income			-			-		-1,182		-1,182		-
	Change in unrealized gains included in other
		comprehensive income (loss)		327			-		-		327		-
	Change in unrealized losses included in other
		comprehensive income (loss)		-208			-		-		-208		-
	Purchases			-			45,414		-		45,414		-
	Issues			-			-		300		300		-432
	Sales			-4,202			-23,406		-		-27,608		-
	Transfers in to Level 3			3,647			-		-		3,647		-
	Transfers out of Level 3			-561			-		-		-561		-
	Level 3, end of period		$	7,546		$	569,393	$	-	$	576,939	$	-
Fair Value Inputs Assets And Liabilities Quantitative Information [Table Text Block]	'
				30-Jun-14
				Fair Value (Level 3)		Valuation Techniques		Unobservable Inputs	Low		High		Weighted Average or Actual
				(U.S. dollars in thousands, except for correlation and commodity curve)
		Net weather and energy related derivative asset	$	708		Historical Analysis and Simulation		Correlation		0		1	Actual
								Weather curve	$	-1,200	$	1,200	Actual
								Commodity curve	$	11.59	$	91.64	Actual

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2014
Earnings Per Share	'
Schedule Of Computation Of Basic And Diluted Earnings Per Share	'
						Three Months Ended						Six Months Ended
						June 30,						June 30,
						2014			2013			2014			2013
		Numerator:
			Net income available to common and participating
				common shareholders	$	74,975		$	52,831		$	171,267		$	144,942
			Less amount allocated to participating
				common shareholders(1)		-2,212			-1,132			-4,988			-2,745
			Net income allocated to common shareholders		$	72,763		$	51,699		$	166,279		$	142,197
		Denominator:
			Weighted average shares – basic			43,350,911			42,621,301			43,265,200			42,526,686
			Share equivalents:
				Options		-			-			283			-
				Restricted share units		-			229			143			679
			Weighted average shares – diluted			43,350,911			42,621,530			43,265,626			42,527,365
		Basic earnings per common share			$	1.68		$	1.21		$	3.84		$	3.34
		Diluted earnings per common share			$	1.68		$	1.21		$	3.84		$	3.34
		(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						Six Months Ended
				June 30,						June 30,
				2014			2013			2014			2013
		Dividends declared per Series A preferred share		$	0.484375		$	0.484375		$	0.96875		$	0.96875
		Dividends declared per Series B preferred share		$	0.46875		$	0.46875		$	0.9375		$	0.9375
		Dividends declared per common share		$	0.34		$	0.32		$	0.68		$	0.64

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2014
Accumulated Other Comprehensive Income	'
Schedule Of Accumulated Other Comprehensive Income	'
			For the Three Months Ended June 30, 2014
			Loss on cash flow hedge			Unrealized gains on available-for-sale securities		Foreign currency translation adjustments		Total
	Beginning balance		$	-1,832		$	69,330	$	21,861	$	89,359
		Other comprehensive income before reclassifications		-			39,676		8,998		48,674
		Amounts reclassified from accumulated other comprehensive income(1)		22			-2,017		-		-1,995
	Net current period other comprehensive income			22			37,659		8,998		46,679
	Ending balance		$	-1,810		$	106,989	$	30,859	$	136,038
	(1) All amounts are net of tax.
			For the Three Months Ended June 30, 2013
			Loss on cash flow hedge			Unrealized gains on available-for-sale securities		Foreign currency translation adjustments		Total
	Beginning balance		$	-1,928		$	136,885	$	2,482	$	137,439
		Other comprehensive loss before reclassifications		-			-96,457		219		-96,238
		Amounts reclassified from accumulated other comprehensive income(1)		29			-9,792		-		-9,763
	Net current period other comprehensive loss			29			-106,249		219		-106,001
	Ending balance		$	-1,899		$	30,636	$	2,701	$	31,438
	(1) All amounts are net of tax.
			Six Months Ended June 30, 2014
			Gains and losses on cash flow hedges			Unrealized gains and losses on available-for-sale securities		Foreign currency translation adjustments		Total
	Beginning balance		$	-1,855		$	45,950	$	18,636	$	62,731
		Other comprehensive income before reclassifications		-			67,341		12,223		79,564
		Amounts reclassified from accumulated other comprehensive income(1)		45			-6,302		-		-6,257
	Net current period other comprehensive income			45			61,039		12,223		73,307
	Ending balance		$	-1,810		$	106,989	$	30,859	$	136,038
	(1) All amounts are net of tax.
			Six Months Ended June 30, 2013
			Gains and losses on cash flow hedges			Unrealized gains and losses on available-for-sale securities		Foreign currency translation adjustments		Total
	Beginning balance		$	-1,944		$	141,731	$	12,676	$	152,463
		Other comprehensive loss before reclassifications		-			-96,360		-9,975		-106,335
		Amounts reclassified from accumulated other comprehensive income(1)		45			-14,735		-		-14,690
	Net current period other comprehensive loss			45			-111,095		-9,975		-121,025
	Ending balance		$	-1,899		$	30,636	$	2,701	$	31,438
	(1) All amounts are net of tax.
Reclassification Out Of Accumulated Other Comprehensive Income	'
		Three Months Ended June 30, 2014
		Details about accumulated other comprehensive income components			Amount reclassified from accumulated other comprehensive income		Affected line item in the Unaudited Condensed Consolidated Statements of Income and Comprehensive Income (Loss)
		Loss on cash flow hedge - Debt		$	22		Interest expense
					22		Total before income taxes
					-		Income tax expense
				$	22		Total net of income taxes
		Unrealized gains on available-for-sale securities		$	-2,068		Net realized and unrealized investment gains
					198		Net impairment losses recognized in earnings
					-1,870		Total before income taxes
					-147		Income tax benefit
				$	-2,017		Total net of income taxes
		Three Months Ended June 30, 2013
		Details about accumulated other comprehensive income components			Amount reclassified from accumulated other comprehensive income		Affected line item in the Unaudited Condensed Consolidated Statements of Income and Comprehensive Income (Loss)
		Loss on cash flow hedge - Debt		$	29		Interest expense
					29		Total before income taxes
					-		Income tax expense
				$	29		Total net of income taxes
		Unrealized gains on available-for-sale securities		$	-11,308		Net realized and unrealized investment gains
					579		Net impairment losses recognized in earnings
					-10,729		Total before income taxes
					937		Income tax expense
				$	-9,792		Total net of income taxes
		Six Months Ended June 30, 2014
		Details about accumulated other comprehensive income components			Amount reclassified from accumulated other comprehensive income		Affected line item in the Unaudited Condensed Consolidated Statements of Income and Comprehensive Income (Loss)
		Gains and losses on cash flow hedges - Debt		$	45		Interest expense
					45		Total before income taxes
					-		Income tax expense
				$	45		Total net of income taxes
		Unrealized (gains) losses on available-for-sale securities		$	-6,331		Net realized and unrealized investment gains
					309		Net impairment losses recognized in earnings
					-6,022		Total before income taxes
					-280		Income tax benefit
				$	-6,302		Total net of income taxes
		Six Months Ended June 30, 2013
		Details about accumulated other comprehensive income components			Amount reclassified from accumulated other comprehensive income		Affected line item in the Unaudited Condensed Consolidated Statements of Income and Comprehensive Income (Loss)
		Gains and losses on cash flow hedges - Debt		$	45		Interest expense
					45		Total before income taxes
					-		Income tax expense
				$	45		Total net of income taxes
		Unrealized gains on available-for-sale securities		$	-17,265		Net realized and unrealized investment gains
					1,385		Net impairment losses recognized in earnings
					-15,880		Total before income taxes
					1,145		Income tax expense
				$	-14,735		Total net of income taxes

Derivatives_Tables

Derivatives (Tables)	6 Months Ended
	Jun. 30, 2014
Derivatives	'
Schedule Of The Fair Value And Related Notional Amounts Of Derivatives Included In The Company's Consolidated Balance Sheet	'
				30-Jun-14				31-Dec-13
						Notional				Notional
				Fair		Principal		Fair		Principal
				Value		Amount		Value		Amount
		Derivatives recorded in other assets
			Foreign exchange forward contracts	$	59	$	16,763	$	251	$	19,269
			Credit default swaps		22		1,815		-		-
			Interest rate swaps		-		-		124		16,100
			Interest rate swaptions		-		23,238		39		24,338
			TBAs		68,815		67,000		93,820		93,840
			Energy and weather contracts		10,992		42,965		14,038		53,986
			Total recorded in other assets	$	79,888			$	108,272
		Derivatives recorded in other liabilities
			Foreign exchange forward contracts	$	201	$	23,632	$	172	$	15,861
			Interest rate swaps		670		22,556		933		12,193
			Interest rate swaptions		-		23,238		543		361,455
			Interest rate futures		-		-		17		103,935
			TBAs		16,279		16,000		28,218		28,000
			Energy and weather contracts		10,284		65,800		19,569		66,113
			Total recorded in other liabilities	$	27,434			$	49,452
			Net derivative asset	$	52,454			$	58,820
Schedule Of The Gains And Losses On The Consolidated Statements Of Income And Comprehensive Income (Loss) From Derivatives	'
				Three Months Ended				Six Months Ended
				June 30,				June 30,
				2014		2013		2014		2013
		Total included in net foreign exchange losses from foreign
			exchange forward contracts	$	-172	$	169	$	-399	$	330
			Futures contracts	$	115	$	-47	$	135	$	-47
			Credit default swaps		14		114		14		116
			Interest rate swaps		-316		-279		-1,081		-161
			Interest rate swaptions		-1		-276		428		-101
			TBAs		1,531		-448		2,456		-465
		Total included in net realized and unrealized investment gains		$	1,343	$	-936	$	1,952	$	-658
		Total included in other underwriting (loss) income from energy
			and weather contracts	$	-40	$	6	$	-299	$	1,172
		Total gains (losses) from derivatives		$	1,131	$	-761	$	1,254	$	844

Segment_Reporting_Tables

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2014
Segment Reporting	'
Summary Of The Segment Revenues, Results And Reserve For Losses And Loss Expenses	'
					Three Months Ended June 30, 2014
						Insurance			Reinsurance				Total
			Revenues
				Gross premiums written		$	321,526		$	367,899			$	689,425
				Ceded premiums written			-142,488			-35,510				-177,998
				Net premiums written			179,038			332,389				511,427
				Net premiums earned			218,563			262,975				481,538
				Other underwriting loss			-			-4,824				-4,824
							218,563			258,151				476,714
			Expenses
				Net losses and loss expenses			149,567			109,629				259,196
				Acquisition expenses			15,128			63,473				78,601
				General and administrative expenses			47,237			39,218				86,455
							211,932			212,320				424,252
			Underwriting income			$	6,631		$	45,831			$	52,462
			Net loss ratio				68.5	%		41.7	%			53.8	%
			Acquisition expense ratio				6.9	%		24.1	%			16.3	%
			General and administrative expense ratio				21.6	%		14.9	%			18	%
			Combined ratio				97	%		80.7	%			88.1	%
			Reserve for losses and loss expenses			$	2,143,921		$	1,819,472			$	3,963,393
					Three Months Ended June 30, 2013
							Insurance			Reinsurance				Total
			Revenues
				Gross premiums written		$	276,941		$	295,769			$	572,710
				Ceded premiums written			-85,439			-22,650				-108,089
				Net premiums written			191,502			273,119				464,621
				Net premiums earned			267,878			275,457				543,335
				Other underwriting income			-			888				888
							267,878			276,345				544,223
			Expenses
				Net losses and loss expenses			215,844			143,214				359,058
				Acquisition expenses			14,968			56,900				71,868
				General and administrative expenses			43,524			37,835				81,359
							274,336			237,949				512,285
			Underwriting (loss) income			$	-6,458		$	38,396			$	31,938
			Net loss ratio				80.6	%		52	%			66.1	%
			Acquisition expense ratio				5.6	%		20.7	%			13.2	%
			General and administrative expense ratio				16.2	%		13.7	%			15	%
			Combined ratio				102.4	%		86.4	%			94.3	%
			Reserve for losses and loss expenses			$	2,242,894		$	1,902,687			$	4,145,581
					Six Months Ended June 30, 2014
							Insurance			Reinsurance				Total
			Revenues
				Gross premiums written		$	973,802		$	873,138			$	1,846,940
				Ceded premiums written			-451,737			-85,071				-536,808
				Net premiums written			522,065			788,067				1,310,132
				Net premiums earned			362,584			515,220				877,804
				Other underwriting loss			-			-6,062				-6,062
							362,584			509,158				871,742
			Expenses
				Net losses and loss expenses			238,100			197,992				436,092
				Acquisition expenses			27,389			123,369				150,758
				General and administrative expenses			88,973			70,688				159,661
							354,462			392,049				746,511
			Underwriting income			$	8,122		$	117,109			$	125,231
			Net loss ratio				65.7	%		38.5	%			49.6	%
			Acquisition expense ratio				7.6	%		23.9	%			17.2	%
			General and administrative expense ratio				24.5	%		13.7	%			18.2	%
			Combined ratio				97.8	%		76.1	%			85	%
					Six Months Ended June 30, 2013
							Insurance			Reinsurance				Total
			Revenues
				Gross premiums written		$	929,884		$	820,188			$	1,750,072
			Ceded premiums written			-333,688			-42,848				-376,536
			Net premiums written			596,196			777,340				1,373,536
			Net premiums earned			419,030			544,422				963,452
			Other underwriting income			-			1,637				1,637
						419,030			546,059				965,089
		Expenses
			Net losses and loss expenses			315,308			262,720				578,028
			Acquisition expenses			29,584			113,920				143,504
			General and administrative expenses			79,151			68,686				147,837
						424,043			445,326				869,369
		Underwriting (loss) income			$	-5,013		$	100,733			$	95,720
		Net loss ratio				75.2	%		48.3	%			60	%
		Acquisition expense ratio				7.1	%		20.9	%			14.9	%
		General and administrative expense ratio				18.9	%		12.6	%			15.3	%
		Combined ratio				101.2	%		81.8	%			90.2	%
Schedule Of Segment Results To Income Before Income Taxes	'
				Three Months Ended
				June 30,
					2014			2013
			Total underwriting income	$	52,462		$	31,938
			Net investment income		39,302			32,468
			Net foreign exchange losses		-319			-3,368
			Net realized and unrealized investment gains		3,411			10,372
			Net impairment losses recognized in earnings		-198			-579
			Amortization of intangibles		-1,623			-1,625
			Interest expense		-9,732			-9,052
			Income before income taxes	$	83,303		$	60,154
			Six Months Ended
			June 30,
				2014			2013
		Total underwriting income	$	125,231		$	95,720
		Net investment income		80,292			81,773
		Net foreign exchange losses		-3,283			-6,295
		Net realized and unrealized investment gains		8,283			16,607
		Net impairment losses recognized in earnings		-309			-1,385
		Amortization of intangibles		-3,240			-3,726
		Interest expense		-18,783			-18,090
		Income before income taxes	$	188,191		$	164,604
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	$	80,540		$	45,826	$	131,633		$	84,537
			Casualty and other specialty		146,728			89,765		87,614			63,373
			Professional lines		74,650			29,846		38,296			27,788
			Property		19,608			13,601		19,398			15,804
		Total Insurance			321,526			179,038		276,941			191,502
		Reinsurance
			Catastrophe		158,372			123,411		155,431			138,041
			Property		42,887			42,886		48,384			44,516
			Casualty		30,875			30,868		54,417			54,419
			Professional lines		84,117			84,117		12,528			12,528
			Specialty		51,648			51,107		25,009			23,615
		Total Reinsurance			367,899			332,389		295,769			273,119
		Total		$	689,425		$	511,427	$	572,710		$	464,621
					Gross			Net		Gross			Net
					premiums			premiums		premiums			premiums
					written			written		written			written
		Business Segment			2014			2014		2013			2013
		Insurance
			Agriculture	$	608,434		$	327,471	$	696,107		$	425,667
			Casualty and other specialty		221,623			131,486		144,081			106,634
			Professional lines		113,430			44,416		59,260			41,991
			Property		30,315			18,692		30,436			21,904
		Total Insurance			973,802			522,065		929,884			596,196
		Reinsurance
			Catastrophe		285,020			202,374		303,297			269,439
			Property		209,300			209,208		196,795			192,927
			Casualty		115,857			114,260		183,809			182,382
			Professional lines		109,736			109,736		24,835			24,835
			Specialty		153,225			152,489		111,452			107,757
		Total Reinsurance			873,138			788,067		820,188			777,340
		Total		$	1,846,940		$	1,310,132	$	1,750,072		$	1,373,536

Commitments_And_Contingencies_

Commitments And Contingencies (Tables)	6 Months Ended
	Jun. 30, 2014
Commitments And Contingencies	'
Schedule Of Percentage Of Net Premiums	'
		Broker	2014		2013
		Marsh & McLennan Companies, Inc.	22.1	%	19.5	%
		Aon Benfield	16	%	15.3	%
		Willis Companies	11.8	%	9.8	%
		Total of largest brokers	49.9	%	44.6	%
Schedule Of Future Minimum Lease Commitments	'
		Twelve months ended June 30,	Amount
		2015	$	15,984
		2016		14,379
		2017		12,157
		2018		11,882
		2019		10,422
		2020 and thereafter		39,173
			$	103,997

Investments_Narrative_Details

Investments (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Investments	'	'	'	'	'
Other investments, invested amount	$450,000,000	'	$450,000,000	'	$440,900,000
Other investments, market value	648,642,000	'	648,642,000	'	617,478,000
Number of available for sale securities in an unrealized loss position	468	'	468	'	880
Number of securities in a continuous unrealized loss position for twelve months or greater	243	'	243	'	71
OTTI losses recognized	198,000	579,000	309,000	1,385,000	'
Unrealized Losses	-11,766,000	'	-11,766,000	'	-49,620,000	[1]
Unrealized Losses, 12 months or greater	($9,432,000)	'	($9,432,000)	'	($5,826,000)	[1]
[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.

Investments_Composition_Of_Net

Investments (Composition Of Net Investment Income) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Investments	'	'	'	'
Available for sale investments	$31,619	$28,666	$61,946	$58,147
Other investments	10,785	6,780	24,327	29,839
Cash and cash equivalents	511	840	1,297	1,291
Investment income	42,915	36,286	87,570	89,277
Investment expenses	-3,613	-3,818	-7,278	-7,504
Net investment income	$39,302	$32,468	$80,292	$81,773

Investments_Summary_Of_Investm

Investments (Summary Of Investment Portfolio By Type) (Details) (USD $)	Jun. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Summary of Investment Holdings [Line Items]	'		'
Fair Value	$6,549,857		$6,500,650
Percentage of Investment	100.00%		100.00%
Fixed Maturity Securities [Member]	'		'
Summary of Investment Holdings [Line Items]	'		'
Fair Value	4,993,099		4,823,964
Percentage of Investment	76.20%		74.20%
Cash and Cash Equivalents [Member]	'		'
Summary of Investment Holdings [Line Items]	'		'
Fair Value	595,910	[1]	771,714	[1]
Percentage of Investment	9.10%	[1]	11.90%	[1]
Other Investments [Member]	'		'
Summary of Investment Holdings [Line Items]	'		'
Fair Value	648,642	[2]	617,478	[2]
Percentage of Investment	9.90%	[2]	9.50%	[2]
Short Term Investments [Member]	'		'
Summary of Investment Holdings [Line Items]	'		'
Fair Value	24,564		35,028
Percentage of Investment	0.40%		0.50%
Equity Securities [Member]	'		'
Summary of Investment Holdings [Line Items]	'		'
Fair Value	$287,642		$252,466
Percentage of Investment	4.40%		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 $)	Jun. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
AAA/Aaa [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	$1,137,895	[1]	$972,820	[1]
Percentage of fixed income portfolio by investment ratings	22.70%	[1]	20.00%	[1]
AA/Aa [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	1,782,465	[1]	1,771,156	[1]
Percentage of fixed income portfolio by investment ratings	35.50%	[1]	36.50%	[1]
A/A [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	999,084	[1]	895,549	[1]
Percentage of fixed income portfolio by investment ratings	19.90%	[1]	18.40%	[1]
BBB [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	421,356	[1]	363,722	[1]
Percentage of fixed income portfolio by investment ratings	8.40%	[1]	7.50%	[1]
Below BBB [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	99,558	[1]	66,791	[1]
Percentage of fixed income portfolio by investment ratings	2.00%	[1]	1.40%	[1]
Not Rated [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	13,185	[1]	19,611	[1]
Percentage of fixed income portfolio by investment ratings	0.30%	[1]	0.40%	[1]
U.S. Government And Agencies Securities [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	564,120	[1]	769,343	[1]
Percentage of fixed income portfolio by investment ratings	11.20%	[1]	15.80%	[1]
Fixed Income Investments [Member]	'		'
Investments By Rating [Line Items]	'		'
Fair Value of fixed income portfolio by investment ratings	$5,017,663	[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 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.

Investments_Contractual_Maturi

Investments (Contractual Maturities Of Fixed Income Securities) (Details) (USD $)	Jun. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'		'
Due within one year, Amortized Cost	$147,587		$144,814
Due within one year, Fair Value	148,630		145,653
Due after one year through five years, Amortized Cost	1,638,278		1,808,001
Due after one year through five years, Fair Value	1,653,175		1,815,240
Due after five years through ten years, Amortized Cost	384,738		290,391
Due after five years through ten years, Fair Value	393,528		288,486
Due after ten years, Amortized Cost	47,496		26,344
Due after ten years, Fair Value	50,325		26,937
Amortized Cost	4,912,191		4,802,580
Debt securities, fair value	4,993,099		4,823,964
Residential Mortgage-Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
No single maturity date, amortized cost	1,202,234		1,192,085
No single maturity date, fair value	1,225,675		1,187,191
Amortized Cost	1,202,234		1,192,085
Debt securities, fair value	1,225,675		1,187,191
Commercial Mortgage-Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
No single maturity date, amortized cost	942,066		932,263
No single maturity date, fair value	967,231		947,677
Amortized Cost	942,066		932,263
Debt securities, fair value	967,231		947,677
Collateralized Loan and Debt Obligations [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
No single maturity date, amortized cost	195,914		92,519
No single maturity date, fair value	197,893		94,552
Amortized Cost	195,914	[1]	92,519	[2]
Debt securities, fair value	197,893	[1]	94,552	[2]
Asset-Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
No single maturity date, amortized cost	378,442		351,192
No single maturity date, fair value	381,206		353,256
Amortized Cost	378,442		351,192
Debt securities, fair value	381,206		353,256
Fixed Income Investments [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
No single maturity date, amortized cost	4,936,755		4,837,609
No single maturity date, fair value	5,017,663		4,858,992
Amortized Cost	4,936,755		4,837,609
Debt securities, fair value	$5,017,663		$4,858,992
[1]	Balances include amounts related to collateralized debt obligations held with total fair values of $11.9 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 $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule Of Equity Method Investments [Line Items]	'	'
Other investments, market value	$648,642	$617,478
Commitments under investment fund classified within other investments	69,709	57,997
Prohibited amount under redemption requests over the next 12 months	111,690	107,109
Alternative Funds [Member]	'	'
Schedule Of Equity Method Investments [Line Items]	'	'
Other investments, market value	487,793	461,141
Commitments under investment fund classified within other investments	69,709	57,997
Prohibited amount under redemption requests over the next 12 months	111,690	107,109
Hedge Funds [Member]	'	'
Schedule Of Equity Method Investments [Line Items]	'	'
Other investments, market value	420,656	401,438
Commitments under investment fund classified within other investments	0	0
Prohibited amount under redemption requests over the next 12 months	44,553	47,406
Private Equity Funds [Member]	'	'
Schedule Of Equity Method Investments [Line Items]	'	'
Other investments, market value	67,137	59,703
Commitments under investment fund classified within other investments	69,709	57,997
Prohibited amount under redemption requests over the next 12 months	67,137	59,703
Specialty Funds [Member]	'	'
Schedule Of Equity Method Investments [Line Items]	'	'
Other investments, market value	160,849	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	113,453	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	47,396	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)	6 Months Ended
	Jun. 30, 2014
Hedge Funds [Member]	'
Schedule Of Equity Method Investments [Line Items]	'
Estimated remaining liquidation period in years	'3 years 0 months 0 days
Estimated liquidation, percentage in next 12 months	89.40%
Hedge Funds [Member] | Maximum [Member]	'
Schedule Of Equity Method Investments [Line Items]	'
Estimated notice period, in days	'90
Hedge Funds [Member] | Minimum [Member]	'
Schedule Of Equity Method Investments [Line Items]	'
Estimated notice period, in days	'30
Private Equity Funds [Member] | Maximum [Member]	'
Schedule Of Equity Method Investments [Line Items]	'
Estimated remaining liquidation period in years	'10 years 0 months 0 days
Private Equity Funds [Member] | Minimum [Member]	'
Schedule Of Equity Method Investments [Line Items]	'
Estimated remaining liquidation period in years	'5 years 0 months 0 days
High Yield Loan Funds [Member] | Maximum [Member]	'
Schedule Of Equity Method Investments [Line Items]	'
Estimated notice period, in days	'90
High Yield Loan Funds [Member] | Minimum [Member]	'
Schedule Of Equity Method Investments [Line Items]	'
Estimated notice period, in days	'30
Convertible Debt Funds [Member]	'
Schedule Of Equity Method Investments [Line Items]	'
Estimated notice period, in days	'5

Investments_Net_Realized_and_U

Investments (Net Realized and Unrealized Investment Gains) (Details) (USD $)	3 Months Ended				6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Investments	'		'		'		'
Gross realized gains on investment sales	$7,387		$16,591		$17,634		$24,011
Gross realized losses on investment sales	-5,319		-5,283		-11,303		-6,746
Change in fair value of derivatives financial instruments	1,343	[1]	-936	[1]	1,952	[1]	-658	[1]
Net realized and unrealized investment gains	$3,411		$10,372		$8,283		$16,607
[1]	For additional information on the Company's 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 $)	Jun. 30, 2014		Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'		'
Debt securities, amortized cost	$4,912,191,000		$4,802,580,000
Debt securities, fair value	4,993,099,000		4,823,964,000
Equity securities, cost	249,463,000		227,828,000
Equity securities, fair value	287,642,000		252,466,000
Gross unrealized loss related to securities, non-credit OTTI	0		100,000
U.S. Government And Agencies Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Debt securities, amortized cost	558,408,000		771,227,000
Debt securities, gross unrealized gains	7,759,000		5,735,000
Debt securities, gross unrealized losses	-2,047,000		-7,619,000
Debt securities, fair value	564,120,000		769,343,000
Non-Credit OTTI	0	[1]	0	[2]
U.S. State And Municipal Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Debt securities, amortized cost	32,578,000		27,138,000
Debt securities, gross unrealized gains	249,000		111,000
Debt securities, gross unrealized losses	-115,000		-395,000
Debt securities, fair value	32,712,000		26,854,000
Non-Credit OTTI	0	[1]	0	[2]
Foreign Government Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Debt securities, amortized cost	230,217,000		183,650,000
Debt securities, gross unrealized gains	2,405,000		1,003,000
Debt securities, gross unrealized losses	-936,000		-2,006,000
Debt securities, fair value	231,686,000		182,647,000
Non-Credit OTTI	0	[1]	0	[2]
Government Guaranteed Corporate Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Debt securities, amortized cost	52,378,000		34,921,000
Debt securities, gross unrealized gains	609,000		274,000
Debt securities, gross unrealized losses	0		-50,000
Debt securities, fair value	52,987,000		35,145,000
Non-Credit OTTI	0	[1]	0	[2]
Corporate Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Debt securities, amortized cost	1,319,954,000		1,217,585,000
Debt securities, gross unrealized gains	21,300,000		16,225,000
Debt securities, gross unrealized losses	-1,665,000		-6,511,000
Debt securities, fair value	1,339,589,000		1,227,299,000
Non-Credit OTTI	0	[1]	0	[2]
Residential Mortgage-Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Debt securities, amortized cost	1,202,234,000		1,192,085,000
Debt securities, gross unrealized gains	27,040,000		17,005,000
Debt securities, gross unrealized losses	-3,599,000		-21,899,000
Debt securities, fair value	1,225,675,000		1,187,191,000
Non-Credit OTTI	-3,959,000	[1]	-4,257,000	[2]
Commercial Mortgage-Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Debt securities, amortized cost	942,066,000		932,263,000
Debt securities, gross unrealized gains	27,461,000		23,423,000
Debt securities, gross unrealized losses	-2,296,000		-8,009,000
Debt securities, fair value	967,231,000		947,677,000
Non-Credit OTTI	-6,000	[1]	-47,000	[2]
Collateralized Loan and Debt Obligations [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Debt securities, amortized cost	195,914,000	[3]	92,519,000	[4]
Debt securities, gross unrealized gains	2,140,000	[3]	2,233,000	[4]
Debt securities, gross unrealized losses	-161,000	[3]	-200,000	[4]
Debt securities, fair value	197,893,000	[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]	'		'
Debt securities, amortized cost	378,442,000		351,192,000
Debt securities, gross unrealized gains	3,125,000		2,919,000
Debt securities, gross unrealized losses	-361,000		-855,000
Debt securities, fair value	381,206,000		353,256,000
Non-Credit OTTI	-153,000	[1]	-163,000	[2]
Fixed Maturity Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Debt securities, amortized cost	4,912,191,000		4,802,580,000
Debt securities, gross unrealized gains	92,088,000		68,928,000
Debt securities, gross unrealized losses	-11,180,000		-47,544,000
Debt securities, fair value	4,993,099,000		4,823,964,000
Non-Credit OTTI	-4,118,000	[1]	-4,467,000	[2]
Short Term Investments [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Debt securities, amortized cost	24,564,000		35,029,000
Debt securities, gross unrealized gains	9,000		1,000
Debt securities, gross unrealized losses	-9,000		-2,000
Debt securities, fair value	24,564,000		35,028,000
Non-Credit OTTI	0	[1]	0	[2]
Fixed Income Investments [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Debt securities, amortized cost	4,936,755,000		4,837,609,000
Debt securities, gross unrealized gains	92,097,000		68,929,000
Debt securities, gross unrealized losses	-11,189,000		-47,546,000
Debt securities, fair value	5,017,663,000		4,858,992,000
Non-Credit OTTI	-4,118,000	[1]	-4,467,000	[2]
Equity Investments [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Equity securities, cost	175,435,000		152,525,000
Equity securities, gross unrealized gains	33,968,000		24,139,000
Equity securities, gross unrealized losses	-571,000		-1,995,000
Equity securities, fair value	208,832,000		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	2,575,000		594,000
Equity securities, gross unrealized losses	0		0
Equity securities, fair value	62,825,000		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	7,548,000		6,325,000
Equity securities, gross unrealized gains	2,211,000		1,977,000
Equity securities, gross unrealized losses	-5,000		-79,000
Equity securities, fair value	9,754,000		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	6,230,000		8,728,000
Equity securities, gross unrealized gains	2,000		2,000
Equity securities, gross unrealized losses	-1,000		0
Equity securities, fair value	6,231,000		8,730,000
Non-Credit OTTI	0	[1]	0	[2]
Total Equity Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Equity securities, cost	249,463,000		227,828,000
Equity securities, gross unrealized gains	38,756,000		26,712,000
Equity securities, gross unrealized losses	-577,000		-2,074,000
Equity securities, fair value	287,642,000		252,466,000
Non-Credit OTTI	0	[1]	0	[2]
Collateralized Debt Obligations [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Debt securities, fair value	$11,900,000		$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 June 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 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]	Balances include amounts related to collateralized debt obligations held with total fair values of $11.9 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 $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, 12 months or greater	($9,432)	($5,826)	[1]
Unrealized Losses	-11,766	-49,620	[1]
U.S. Government And Agencies Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-44	-7,359	[1]
Fair Value, Less than 12 months	26,863	382,593
Unrealized Losses, 12 months or greater	-2,003	-260	[1]
Fair Value, 12 months or greater	117,013	6,050
Unrealized Losses	-2,047	-7,619	[1]
Fair Value	143,876	388,643
U.S. State And Municipal Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-41	-395	[1]
Fair Value, Less than 12 months	4,829	20,452
Unrealized Losses, 12 months or greater	-74	0	[1]
Fair Value, 12 months or greater	6,842	0
Unrealized Losses	-115	-395	[1]
Fair Value	11,671	20,452
Foreign Government Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-660	-1,981	[1]
Fair Value, Less than 12 months	58,447	139,503
Unrealized Losses, 12 months or greater	-276	-25	[1]
Fair Value, 12 months or greater	18,721	5,261
Unrealized Losses	-936	-2,006	[1]
Fair Value	77,168	144,764
Government Guaranteed Corporate Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	0	-50	[1]
Fair Value, Less than 12 months	'	13,326
Unrealized Losses, 12 months or greater	0	0	[1]
Fair Value, 12 months or greater	'	0
Unrealized Losses	0	-50	[1]
Fair Value	'	13,326
Corporate Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-370	-5,959	[1]
Fair Value, Less than 12 months	142,038	478,287
Unrealized Losses, 12 months or greater	-1,295	-552	[1]
Fair Value, 12 months or greater	103,889	28,690
Unrealized Losses	-1,665	-6,511	[1]
Fair Value	245,927	506,977
Residential Mortgage-Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-155	-17,542	[1]
Fair Value, Less than 12 months	31,998	514,702
Unrealized Losses, 12 months or greater	-3,444	-4,357	[1]
Fair Value, 12 months or greater	163,473	102,446
Unrealized Losses	-3,599	-21,899	[1]
Fair Value	195,471	617,148
Commercial Mortgage-Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-436	-7,681	[1]
Fair Value, Less than 12 months	53,792	384,548
Unrealized Losses, 12 months or greater	-1,860	-328	[1]
Fair Value, 12 months or greater	100,956	16,804
Unrealized Losses	-2,296	-8,009	[1]
Fair Value	154,748	401,352
Collateralized Loan and Debt Obligations [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-51	-48	[1]
Fair Value, Less than 12 months	60,408	20,733
Unrealized Losses, 12 months or greater	-110	-152	[1]
Fair Value, 12 months or greater	1,839	2,379
Unrealized Losses	-161	-200	[1]
Fair Value	62,247	23,112
Asset-Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-97	-703	[1]
Fair Value, Less than 12 months	88,237	157,172
Unrealized Losses, 12 months or greater	-264	-152	[1]
Fair Value, 12 months or greater	24,218	7,011
Unrealized Losses	-361	-855	[1]
Fair Value	112,455	164,183
Fixed Maturity Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-1,854	-41,718	[1]
Fair Value, Less than 12 months	466,612	2,111,316
Unrealized Losses, 12 months or greater	-9,326	-5,826	[1]
Fair Value, 12 months or greater	536,951	168,641
Unrealized Losses	-11,180	-47,544	[1]
Fair Value	1,003,563	2,279,957
Short Term Investments [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-9	-2	[1]
Fair Value, Less than 12 months	14,936	2,468
Unrealized Losses, 12 months or greater	0	0	[1]
Fair Value, 12 months or greater	0	0
Unrealized Losses	-9	-2	[1]
Fair Value	14,936	2,468
Fixed Income Investments [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-1,863	-41,720	[1]
Fair Value, Less than 12 months	481,548	2,113,784
Unrealized Losses, 12 months or greater	-9,326	-5,826	[1]
Fair Value, 12 months or greater	536,951	168,641
Unrealized Losses	-11,189	-47,546	[1]
Fair Value	1,018,499	2,282,425
Equity Investments [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-467	-1,995	[1]
Fair Value, Less than 12 months	11,368	36,751
Unrealized Losses, 12 months or greater	-104	0	[1]
Fair Value, 12 months or greater	7,276	0
Unrealized Losses	-571	-1,995	[1]
Fair Value	18,644	36,751
Emerging Market Debt Funds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	0	0	[1]
Fair Value, Less than 12 months	'	0
Unrealized Losses, 12 months or greater	0	0	[1]
Fair Value, 12 months or greater	'	0
Unrealized Losses	0	0	[1]
Fair Value	'	0
Preferred Equity Investments [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-3	-79	[1]
Fair Value, Less than 12 months	122	2,987
Unrealized Losses, 12 months or greater	-2	0	[1]
Fair Value, 12 months or greater	200	0
Unrealized Losses	-5	-79	[1]
Fair Value	322	2,987
Short-term Fixed Income Fund [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-1	0	[1]
Fair Value, Less than 12 months	2,899	0
Unrealized Losses, 12 months or greater	0	0	[1]
Fair Value, 12 months or greater	0	0
Unrealized Losses	-1	0	[1]
Fair Value	2,899	0
Total Equity Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Unrealized Losses, Less than 12 months	-471	-2,074	[1]
Fair Value, Less than 12 months	14,389	39,738
Unrealized Losses, 12 months or greater	-106	0	[1]
Fair Value, 12 months or greater	7,476	0
Unrealized Losses	-577	-2,074	[1]
Fair Value	$21,865	$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.

Investments_Analysis_Of_OTTI_D

Investments (Analysis Of OTTI) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Investments	'	'	'	'
Total other-than-temporary impairment losses	($198)	($579)	($309)	($1,385)
Portion of loss recognized in other comprehensive income (loss)	0	0	0	0
Net impairment losses recognized in earnings	($198)	($579)	($309)	($1,385)

Investments_Credit_Losses_Roll

Investments (Credit Losses Rollforward) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Investments	'	'	'	'
Beginning balance	($1,520)	($1,883)	($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	79	114	112	231
Ending balance	($1,441)	($1,769)	($1,441)	($1,769)

Fair_Value_Measurement_Narrati

Fair Value Measurement (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Fair Value, Assets and Liabilities [Line Items]	'	'	'	'	'
Net impairment losses recognized in earnings	$198	$579	$309	$1,385	'
Derivative Assets	79,888	'	79,888	'	108,272
Derivative Liabilities	27,434	'	27,434	'	49,452
Transfers into Level 3	2,886	383	5,003	3,647	'
Transfers out of Level 3	-1,589	-505	-1,852	-561	'
Energy Related Derivative [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities [Line Items]	'	'	'	'	'
Derivative Assets	10,992	'	10,992	'	14,038
Derivative Liabilities	10,284	'	10,284	'	19,569
Significant Unobservable Inputs (Level 3) [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities [Line Items]	'	'	'	'	'
Percentage of level 3 assets	11.10%	'	11.10%	'	10.90%
Net impairment losses recognized in earnings	'	'	0	0	'
Derivative Assets	10,992	'	10,992	'	14,038
Derivative Liabilities	$10,284	'	$10,284	'	$19,569

Fair_Value_Measurement_Schedul

Fair Value Measurement (Schedule Of Available For Sale Investments, Other Investments, Derivative Instruments And Debt) (Details) (USD $)	Jun. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	$4,993,099		$4,823,964
Short term investments	24,564		35,028
Equity securities	287,642		252,466
Other investments	648,642		617,478
Other assets (see Note 7)	79,888		108,272
Total assets	6,033,835		5,837,208
Other liabilities (see Note 7)	27,434		49,452
Debt	600,720		575,115
Total liabilities	628,154		624,567
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Short term investments	0		0
Equity securities	153,890		126,506
Other investments	0		0
Other assets (see Note 7)	0		0
Total assets	169,885		146,754
Other liabilities (see Note 7)	0		0
Debt	0		0
Total liabilities	0		0
Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Short term investments	24,564		35,028
Equity securities	133,752		125,960
Other investments	0		0
Other assets (see Note 7)	68,896		94,234
Total assets	5,194,801		5,051,610
Other liabilities (see Note 7)	17,150		29,883
Debt	600,720		575,115
Total liabilities	617,870		604,998
Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Short term investments	0		0
Equity securities	0		0
Other investments	648,642		617,478
Other assets (see Note 7)	10,992		14,038
Total assets	669,149		638,844
Other liabilities (see Note 7)	10,284		19,569
Debt	0		0
Total liabilities	10,284		19,569
U.S. Government And Agencies Securities [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	564,120		769,343
U.S. Government And Agencies Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	15,995		20,248
U.S. Government And Agencies Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	548,125		749,095
U.S. Government And Agencies Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	0		0
U.S. State And Municipal Securities [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	32,712		26,854
U.S. State And Municipal Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	0		0
U.S. State And Municipal Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	32,712		26,854
U.S. State And Municipal Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	0		0
Foreign Government Securities [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	231,686		182,647
Foreign Government Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	0		0
Foreign Government Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	231,686		182,647
Foreign Government Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	0		0
Government Guaranteed Corporate Securities [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	52,987		35,145
Government Guaranteed Corporate Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	0		0
Government Guaranteed Corporate Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	52,987		35,145
Government Guaranteed Corporate Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	0		0
Corporate Securities [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	1,339,589		1,227,299
Corporate Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	0		0
Corporate Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	1,338,871		1,226,553
Corporate Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	718		746
Residential Mortgage-Backed Securities [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	1,225,675		1,187,191
Residential Mortgage-Backed Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	0		0
Residential Mortgage-Backed Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	1,222,760		1,186,943
Residential Mortgage-Backed Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	2,915		248
Commercial Mortgage-Backed Securities [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	967,231		947,677
Commercial Mortgage-Backed Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	0		0
Commercial Mortgage-Backed Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	966,594		946,794
Commercial Mortgage-Backed Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	637		883
Collateralized Loan and Debt Obligations [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	197,893	[1]	94,552	[2]
Collateralized Loan and Debt Obligations [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	0		0
Collateralized Loan and Debt Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	195,667		92,095
Collateralized Loan and Debt Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	2,226		2,457
Asset-Backed Securities [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	381,206		353,256
Asset-Backed Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	0		0
Asset-Backed Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	378,187		350,262
Asset-Backed Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	3,019		2,994
Fixed Maturity Securities [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	4,993,099		4,823,964
Fixed Maturity Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	15,995		20,248
Fixed Maturity Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	4,967,589		4,796,388
Fixed Maturity Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Total fixed maturity investments	9,515		7,328
Equity Investments [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	208,832		174,669
Equity Investments [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	147,659		117,776
Equity Investments [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	61,173		56,893
Equity Investments [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	0		0
Emerging Market Debt Funds [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	62,825		60,844
Emerging Market Debt Funds [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	0		0
Emerging Market Debt Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	62,825		60,844
Emerging Market Debt Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	0		0
Preferred Equity Investments [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	9,754		8,223
Preferred Equity Investments [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	0		0
Preferred Equity Investments [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	9,754		8,223
Preferred Equity Investments [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	0		0
Short-term Fixed Income Fund [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	6,231		8,730
Short-term Fixed Income Fund [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	6,231		8,730
Short-term Fixed Income Fund [Member] | Significant Other Observable Inputs (Level 2) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	0		0
Short-term Fixed Income Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	0		0
Total Equity Securities [Member]	'		'
Fair Value, Assets and Liabilities [Line Items]	'		'
Equity securities	$287,642		$252,466
[1]	Balances include amounts related to collateralized debt obligations held with total fair values of $11.9 million.
[2]	Balances include amounts related to collateralized debt obligations held with total fair values of $18.7 million.

Fair_Value_Measurement_Reconci

Fair Value Measurement (Reconciliation Of The Beginning And Ending Balances For Fixed Maturity And Other Investments Measured At Fair Value On A Recurring Basis Using Level 3 Inputs) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]	'	'	'	'
Level 3, beginning of period	$639,431	$564,535	$638,844	$526,925
Total equity income and realized gains included in earnings	16,322	16,462	35,525	41,950
Total equity losses and losses included in earnings	-5,501	-9,641	-11,172	-12,065
Change in unrealized gains included in other comprehensive income (loss)	89	243	200	327
Change in unrealized losses included in other comprehensive income (loss)	-36	-154	-151	-208
Purchases	21,867	23,424	26,541	45,414
Sales	-6,780	-17,802	-20,743	-27,608
Transfers into Level 3	2,886	383	5,003	3,647
Transfers out of Level 3	-1,589	-505	-1,852	-561
Level 3, end of period	669,149	576,939	669,149	576,939
Fixed Maturity Investments [Member]	'	'	'	'
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]	'	'	'	'
Level 3, beginning of period	8,985	9,814	7,328	8,497
Total equity income and realized gains included in earnings	36	43	53	48
Total equity losses and losses included in earnings	0	-2	-26	-2
Change in unrealized gains included in other comprehensive income (loss)	89	243	200	327
Change in unrealized losses included in other comprehensive income (loss)	-36	-154	-151	-208
Purchases	0	0	0	0
Sales	-856	-2,276	-1,040	-4,202
Transfers into Level 3	2,886	383	5,003	3,647
Transfers out of Level 3	-1,589	-505	-1,852	-561
Level 3, end of period	9,515	7,546	9,515	7,546
Other Investments [Member]	'	'	'	'
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]	'	'	'	'
Level 3, beginning of period	621,914	554,715	617,478	517,546
Total equity income and realized gains included in earnings	16,286	16,419	35,472	41,902
Total equity losses and losses included in earnings	-5,501	-9,639	-11,146	-12,063
Change in unrealized gains included in other comprehensive income (loss)	0	0	0	0
Change in unrealized losses included in other comprehensive income (loss)	0	0	0	0
Purchases	21,867	23,424	26,541	45,414
Sales	-5,924	-15,526	-19,703	-23,406
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Level 3, end of period	$648,642	$569,393	$648,642	$569,393

Fair_Value_Measurement_Reconci1

Fair Value Measurement (Reconciliation Of The Beginning And Ending Balances For Derivative Assets and Liabilities Measured At Fair Value On A Recurring Basis Using Level 3 Inputs) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]	'	'	'	'
Total income included in other underwriting (loss) income	$11,241	$0	$15,216	$0
Total loss included in other underwriting (loss) income	-11,722	-6	-18,610	-1,182
Issues	2,941	0	3,581	300
Settlements	0	'	-3,233	'
Other Assets [Member]	'	'	'	'
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]	'	'	'	'
Level 3, beginning of period, other assets (liabilities)	8,532	6	14,038	882
Total income included in other underwriting (loss) income	11,241	0	15,216	0
Total loss included in other underwriting (loss) income	-11,722	-6	-18,610	-1,182
Purchases	'	0	'	0
Issues	2,941	0	3,581	300
Settlements	0	'	-3,233	'
Level 3, end of period, other assets (liabilities)	10,992	0	10,992	0
Other Liabilities [Member]	'	'	'	'
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]	'	'	'	'
Level 3, beginning of period, other assets (liabilities)	-13,448	-12	-19,569	-1,922
Total income included in other underwriting (loss) income	12,622	12	20,048	2,354
Total loss included in other underwriting (loss) income	-12,177	0	-16,953	0
Purchases	'	0	'	0
Issues	-5,883	0	-7,163	-432
Settlements	8,602	'	13,353	'
Level 3, end of period, other assets (liabilities)	($10,284)	$0	($10,284)	$0

Fair_Value_Measurement_Quantit

Fair Value Measurement (Quantitative Information Used As Level 3 Inputs) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014
			Significant Unobservable Inputs (Level 3) [Member]	Significant Unobservable Inputs (Level 3) [Member]	Significant Unobservable 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]	'	'	'	'	'
Correlation	'	'	'	1	0
Weather curve	'	'	'	'1,200	'(1,200)
Commodity curve	'	'	'	$91.64	$11.59
Net derivative asset	$52,454,000	$58,820,000	($708,000)	'	'

Earnings_Per_Share_Schedule_Of

Earnings Per Share (Schedule Of Computing Basic And Diluted Earnings Per Share) (Details) (USD $)	3 Months Ended				6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Net income available to common and participating common shareholders	$74,975		$52,831		$171,267		$144,942
Less amount allocated to participating common shareholders	-2,212	[1]	-1,132	[1]	-4,988	[1]	-2,745	[1]
Net income allocated to common shareholders	$72,763		$51,699		$166,279		$142,197
Weighted average shares - basic	43,350,911		42,621,301		43,265,200		42,526,686
Weighted average shares - diluted	43,350,911		42,621,530		43,265,626		42,527,365
Basic earnings per common share	$1.68		$1.21		$3.84		$3.34
Diluted earnings per common share	$1.68		$1.21		$3.84		$3.34
Employee Stock Option [Member]	'		'		'		'
Share equivalents	0		0		283		0
Restricted Stock [Member]	'		'		'		'
Share equivalents	0		229		143		679
[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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Dividend Per Share Basic [Line Items]	'	'	'	'
Dividends declared per common share	$0.34	$0.32	$0.68	$0.64
Series A Preferred Stock [Member]	'	'	'	'
Dividend Per Share Basic [Line Items]	'	'	'	'
Dividends declared per preferred share	$0.48	$0.48	$0.97	$0.97
Series B Preferred Stock [Member]	'	'	'	'
Dividend Per Share Basic [Line Items]	'	'	'	'
Dividends declared per preferred share	$0.47	$0.47	$0.94	$0.94

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income (Schedule Of Changes In Accumulated Other Comprehensive Income By Component) (Details) (USD $)	3 Months Ended				6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Beginning balance	$89,359		$137,439		$62,731		$152,463
Other comprehensive income before reclassifications	48,674		-96,238		79,564		-106,335
Amounts reclassified from accumulated other comprehensive income	-1,995	[1]	-9,763	[1]	-6,257	[1]	-14,690	[1]
Other comprehensive income (loss)	46,679		-106,001		73,307		-121,025
Ending balance	136,038		31,438		136,038		31,438
Accumulated Derivative Loss On Cash Flow Hedging Instruments [Member]	'		'		'		'
Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Beginning balance	-1,832		-1,928		-1,855		-1,944
Other comprehensive income before reclassifications	0		0		0		0
Amounts reclassified from accumulated other comprehensive income	22	[1]	29	[1]	45	[1]	45	[1]
Other comprehensive income (loss)	22		29		45		45
Ending balance	-1,810		-1,899		-1,810		-1,899
Unrealized Holding Gains And Losses On AFS Investments, Net Of Deferred Taxes [Member]	'		'		'		'
Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Beginning balance	69,330		136,885		45,950		141,731
Other comprehensive income before reclassifications	39,676		-96,457		67,341		-96,360
Amounts reclassified from accumulated other comprehensive income	-2,017	[1]	-9,792	[1]	-6,302	[1]	-14,735	[1]
Other comprehensive income (loss)	37,659		-106,249		61,039		-111,095
Ending balance	106,989		30,636		106,989		30,636
Cumulative Foreign Currency Translation Adjustments [Member]	'		'		'		'
Accumulated Other Comprehensive Income [Line Items]	'		'		'		'
Beginning balance	21,861		2,482		18,636		12,676
Other comprehensive income before reclassifications	8,998		219		12,223		-9,975
Amounts reclassified from accumulated other comprehensive income	0	[1]	0	[1]	0	[1]	0	[1]
Other comprehensive income (loss)	8,998		219		12,223		-9,975
Ending balance	$30,859		$2,701		$30,859		$2,701
[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		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Interest expense	($9,732)	($9,052)	($18,783)	($18,090)
Net realized and unrealized investment gains	3,411	10,372	8,283	16,607
Net impairment losses recognized in earnings	-198	-579	-309	-1,385
Income before income taxes	83,303	60,154	188,191	164,604
Income tax (expense) benefit	-140	865	-548	-3,286
Net income	83,163	61,019	187,643	161,318
Accumulated Derivative Loss On Cash Flow Hedging Instruments [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]	'	'	'	'
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Interest expense	22	29	45	45
Income before income taxes	22	29	45	45
Income tax (expense) benefit	0	0	0	0
Net income	22	29	45	45
Unrealized Holding Gains And Losses On AFS Investments, Net Of Deferred Taxes [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	-2,068	-11,308	-6,331	-17,265
Net impairment losses recognized in earnings	198	579	309	1,385
Income before income taxes	-1,870	-10,729	-6,022	-15,880
Income tax (expense) benefit	-147	937	-280	1,145
Net income	($2,017)	($9,792)	($6,302)	($14,735)

Derivatives_Schedule_Of_Deriva

Derivatives (Schedule Of Derivative Fair Value And Notional Amount) (Details) (USD $)	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]	'	'
Derivative recorded in other liabilities, Fair Value	$27,434,000	$49,452,000
Derivatives recorded in other assets, Fair Value	79,888,000	108,272,000
Net derivative asset, Fair Value	52,454,000	58,820,000
Derivative assets traded under master netting agreements	79,900,000	108,300,000
Derivative liabilities traded under master netting agreements	27,400,000	49,400,000
Foreign Exchange Forward Contracts [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative recorded in other liabilities, Fair Value	201,000	172,000
Derivatives recorded in other assets, Fair Value	59,000	251,000
Derivatives recorded in other asset, Notional Principal Amount	16,763,000	19,269,000
Derivatives recorded in other liabilities, Notional Principal Amount	23,632,000	15,861,000
Credit Default Swaps [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivatives recorded in other assets, Fair Value	22,000	0
Derivatives recorded in other asset, Notional Principal Amount	1,815,000	0
Original term of credit default swap, in years	'5 years 0 months 0 days	'
Interest Rate Swaps [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative recorded in other liabilities, Fair Value	670,000	933,000
Derivatives recorded in other assets, Fair Value	0	124,000
Derivatives recorded in other asset, Notional Principal Amount	0	16,100,000
Derivatives recorded in other liabilities, Notional Principal Amount	22,556,000	12,193,000
Interest Rate Swaptions [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative recorded in other liabilities, Fair Value	0	543,000
Derivatives recorded in other assets, Fair Value	0	39,000
Derivatives recorded in other asset, Notional Principal Amount	23,238,000	24,338,000
Derivatives recorded in other liabilities, Notional Principal Amount	23,238,000	361,455,000
TBA [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative recorded in other liabilities, Fair Value	16,279,000	28,218,000
Derivatives recorded in other assets, Fair Value	68,815,000	93,820,000
Derivatives recorded in other asset, Notional Principal Amount	67,000,000	93,840,000
Derivatives recorded in other liabilities, Notional Principal Amount	16,000,000	28,000,000
Energy and weather contracts [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative recorded in other liabilities, Fair Value	10,284,000	19,569,000
Derivatives recorded in other assets, Fair Value	10,992,000	14,038,000
Derivatives recorded in other asset, Notional Principal Amount	42,965,000	53,986,000
Derivatives recorded in other liabilities, Notional Principal Amount	65,800,000	66,113,000
Interest Rate Future [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative recorded in other liabilities, Fair Value	0	17,000
Derivatives recorded in other liabilities, Notional Principal Amount	$0	$103,935,000

Derivatives_Schedule_Of_Deriva1

Derivatives (Schedule Of Derivative Gain (Loss)) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative [Line Items]	'	'	'	'
Derivatives included in net realized and unrealized investment gains	$1,343	($936)	$1,952	($658)
Total gains (losses) from derivatives	1,131	-761	1,254	844
Foreign Exchange Forward Contracts [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in net foreign exchange losses from foreign exchange forward contracts	-172	169	-399	330
Interest Rate Future [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in net realized and unrealized investment gains	115	-47	135	-47
Credit Default Swaps [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in net realized and unrealized investment gains	14	114	14	116
Interest Rate Swaps [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in net realized and unrealized investment gains	-316	-279	-1,081	-161
Interest Rate Swaptions [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in net realized and unrealized investment gains	-1	-276	428	-101
TBA [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in net realized and unrealized investment gains	1,531	-448	2,456	-465
Energy and weather contracts [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Derivatives included in other underwriting (loss) income from energy and weather contracts	($40)	$6	($299)	$1,172

StockBased_Employee_Compensati1

Stock-Based Employee Compensation And Other Stock Plans (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Number of options granted	0	800,000	0	800,000
Number of options expired	0	'	0	'
Number of options vested	160,000	160,000	160,000	160,000
Number of options exercised	15,000	12,501	15,000	24,501
Total intrinsic value of options exercised	$300,000	$300,000	$300,000	$500,000
Proceeds from stock options exercised	500,000	300,000	500,000	600,000
Options weighted average grant date fair value	'	10,200,000	0	10,200,000
Number of restricted shares and RSUs granted	97,646	727,271	433,417	1,070,655
Restricted shares and RSUs weighted average grant date fair value	5,100,000	35,100,000	22,700,000	50,300,000
Aggregate fair value of restricted shares and RSUs vested	8,300,000	7,800,000	18,500,000	16,900,000
Expenses related to employee stock purchase plan	55,000	44,000	109,000	82,000
Employee Stock Option [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Compensation costs recognized	900,000	2,400,000	2,000,000	2,400,000
Compensation costs not yet recognized - stock options	3,700,000	7,800,000	3,700,000	7,800,000
Restricted Stock [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Compensation costs recognized	6,600,000	8,800,000	15,800,000	13,500,000
Compensation costs not yet recognized - restricted stock	$31,800,000	$38,500,000	$31,800,000	$38,500,000

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		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]	'	'	'	'	'
Gross premiums written	$689,425	$572,710	$1,846,940	$1,750,072	'
Ceded premiums written	-177,998	-108,089	-536,808	-376,536	'
Net premiums written	511,427	464,621	1,310,132	1,373,536	'
Net premiums earned	481,538	543,335	877,804	963,452	'
Other underwriting (loss) income	-4,824	888	-6,062	1,637	'
Total revenue	476,714	544,223	871,742	965,089	'
Net losses and loss expenses	259,196	359,058	436,092	578,028	'
Acquisition expenses	78,601	71,868	150,758	143,504	'
General and administrative expenses	86,455	81,359	159,661	147,837	'
Total expenses	424,252	512,285	746,511	869,369	'
Underwriting income (loss)	52,462	31,938	125,231	95,720	'
Net loss ratio	53.80%	66.10%	49.60%	60.00%	'
Acquisition expense ratio	16.30%	13.20%	17.20%	14.90%	'
General and administrative expense ratio	18.00%	15.00%	18.20%	15.30%	'
Combined ratio	88.10%	94.30%	85.00%	90.20%	'
Reserve for losses and loss expenses	3,963,393	4,145,581	3,963,393	4,145,581	4,002,259
Insurance [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Gross premiums written	321,526	276,941	973,802	929,884	'
Ceded premiums written	-142,488	-85,439	-451,737	-333,688	'
Net premiums written	179,038	191,502	522,065	596,196	'
Net premiums earned	218,563	267,878	362,584	419,030	'
Other underwriting (loss) income	0	0	0	0	'
Total revenue	218,563	267,878	362,584	419,030	'
Net losses and loss expenses	149,567	215,844	238,100	315,308	'
Acquisition expenses	15,128	14,968	27,389	29,584	'
General and administrative expenses	47,237	43,524	88,973	79,151	'
Total expenses	211,932	274,336	354,462	424,043	'
Underwriting income (loss)	6,631	-6,458	8,122	-5,013	'
Net loss ratio	68.50%	80.60%	65.70%	75.20%	'
Acquisition expense ratio	6.90%	5.60%	7.60%	7.10%	'
General and administrative expense ratio	21.60%	16.20%	24.50%	18.90%	'
Combined ratio	97.00%	102.40%	97.80%	101.20%	'
Reserve for losses and loss expenses	2,143,921	2,242,894	2,143,921	2,242,894	'
Reinsurance [Member]	'	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'	'
Gross premiums written	367,899	295,769	873,138	820,188	'
Ceded premiums written	-35,510	-22,650	-85,071	-42,848	'
Net premiums written	332,389	273,119	788,067	777,340	'
Net premiums earned	262,975	275,457	515,220	544,422	'
Other underwriting (loss) income	-4,824	888	-6,062	1,637	'
Total revenue	258,151	276,345	509,158	546,059	'
Net losses and loss expenses	109,629	143,214	197,992	262,720	'
Acquisition expenses	63,473	56,900	123,369	113,920	'
General and administrative expenses	39,218	37,835	70,688	68,686	'
Total expenses	212,320	237,949	392,049	445,326	'
Underwriting income (loss)	45,831	38,396	117,109	100,733	'
Net loss ratio	41.70%	52.00%	38.50%	48.30%	'
Acquisition expense ratio	24.10%	20.70%	23.90%	20.90%	'
General and administrative expense ratio	14.90%	13.70%	13.70%	12.60%	'
Combined ratio	80.70%	86.40%	76.10%	81.80%	'
Reserve for losses and loss expenses	$1,819,472	$1,902,687	$1,819,472	$1,902,687	'

Segment_Reporting_Schedule_Of_

Segment Reporting (Schedule Of Segment Results To Income Before Income Taxes) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting	'	'	'	'
Total underwriting income	$52,462	$31,938	$125,231	$95,720
Net investment income	39,302	32,468	80,292	81,773
Net foreign exchange losses	-319	-3,368	-3,283	-6,295
Net realized and unrealized investment gains	3,411	10,372	8,283	16,607
Net impairment losses recognized in earnings	-198	-579	-309	-1,385
Amortization of intangibles	-1,623	-1,625	-3,240	-3,726
Interest expense	-9,732	-9,052	-18,783	-18,090
Income before income taxes	$83,303	$60,154	$188,191	$164,604

Segment_Reporting_Schedule_Of_1

Segment Reporting (Schedule Of Gross And Net Premiums By Line Of Business) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	$689,425	$572,710	$1,846,940	$1,750,072
Net premiums written	511,427	464,621	1,310,132	1,373,536
Insurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	321,526	276,941	973,802	929,884
Net premiums written	179,038	191,502	522,065	596,196
Agriculture Insurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	80,540	131,633	608,434	696,107
Net premiums written	45,826	84,537	327,471	425,667
Casualty And Other Specialty Insurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	146,728	87,614	221,623	144,081
Net premiums written	89,765	63,373	131,486	106,634
Professional Lines Insurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	74,650	38,296	113,430	59,260
Net premiums written	29,846	27,788	44,416	41,991
Property Insurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	19,608	19,398	30,315	30,436
Net premiums written	13,601	15,804	18,692	21,904
Reinsurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	367,899	295,769	873,138	820,188
Net premiums written	332,389	273,119	788,067	777,340
Catastrophe Reinsurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	158,372	155,431	285,020	303,297
Net premiums written	123,411	138,041	202,374	269,439
Casualty Reinsurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	30,875	54,417	115,857	183,809
Net premiums written	30,868	54,419	114,260	182,382
Property Reinsurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	42,887	48,384	209,300	196,795
Net premiums written	42,886	44,516	209,208	192,927
Professional Lines Reinsurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	84,117	12,528	109,736	24,835
Net premiums written	84,117	12,528	109,736	24,835
Specialty Reinsurance [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Gross premiums written	51,648	25,009	153,225	111,452
Net premiums written	$51,107	$23,615	$152,489	$107,757

Commitments_And_Contingencies_1

Commitments And Contingencies (Narrative) (Details) (USD $)	6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Commitments And Contingencies	'	'	'
Investments pledged under letters of credit facility	$250.20	'	$302.70
Securities pledged as collateral obligation	128.7	'	146.1
Total lease expenses under operating leases	8.2	7.1	'
Ceded Credit Risk [Line Items]	'	'	'
Reinsurance recoverables	751.8	'	758
Ceded Credit Risk Secured [Member]	'	'	'
Ceded Credit Risk [Line Items]	'	'	'
Reinsurance recoverables	$87.60	'	$14.20

Commitments_And_Contingencies_2

Commitments And Contingencies (Deposits) (Details) (US, USD $)	Jun. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
US	'	'
Statutory Accounting Practices [Line Items]	'	'
Assets Held by Insurance Regulators	$274.60	$273.70

Commitments_And_Contingencies_3

Commitments And Contingencies (LOC) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Other Commitments [Line Items]	'	'
Letters of credit outstanding, amount	$216.80	$260.30
Maximum borrowing capacity	700	'
ANZ [Member]	'	'
Other Commitments [Line Items]	'	'
Letters of credit outstanding, amount	1.4	0
Maximum borrowing capacity	$50	'

Commitments_And_Contingencies_4

Commitments And Contingencies (Schedule Of Future Minimum Lease Commitments) (Details) (USD $)	Jun. 30, 2014
In Thousands, unless otherwise specified
Commitments And Contingencies	'
2015	$15,984
2016	14,379
2017	12,157
2018	11,882
2019	10,422
2020 and thereafter	39,173
Total	$103,997

Commitments_And_Contingencies_5

Commitments And Contingencies (Schedule Of Percentage Of Net Premiums) (Details)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Revenue from External Customer [Line Items]	'	'
Percentage of net premium written	49.90%	44.60%
Aon Benfield [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Percentage of net premium written	16.00%	15.30%
Marsh & Mclennan Companies, Inc. [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Percentage of net premium written	22.10%	19.50%
Willis Companies [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Percentage of net premium written	11.80%	9.80%

Commitments_And_Contingencies_6

Commitments And Contingencies (Option) (Details) (USD $)	6 Months Ended
In Millions, except Per Share data, unless otherwise specified	Jun. 30, 2014
Option Indexed To Issuers 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
Option Indexed To Issuers Equity Percentage Of Stock Acquired	40.00%
Option Indexed To Issuers Equity Payment	$26.30
Call Option [Member]	'
Option Indexed To Issuers Equity [Line Items]	'
Option Indexed To Issuers Equity Acquisition Percentage	95.00%
Option Indexed To Issuers Equity Amount	250
Period option is exercisable, in days	'60
Option Indexed To Issuers Equity Strike Price	$50.03
Period transfer of shares purchased under option is restricted, in months	'12
Call Option [Member] | Maximum [Member] | Chief Executive Officer [Member]	'
Option Indexed To Issuers Equity [Line Items]	'
Amount of equity issuance subject to exception	25
Call Option [Member] | Maximum [Member] | Investor [Member]	'
Option Indexed To Issuers Equity [Line Items]	'
Amount of equity issuance subject to exception	$100

Commitments_And_Contingencies_7

Commitments And Contingencies (Warrants) (Details) (USD $)	6 Months Ended
	Jun. 30, 2014
Warrants And Rights Note Disclosure [Abstract]	'
Class Of Warrant Or Right Exercise Price Of Warrants Or Rights	$58.86
Term of warrrants, in years	'10
Percentage of number of ordinary shares acquired available under option	38.50%

Commitments_And_Contingencies_8

Commitments And Contingencies (Agreement) (Details) (Chief Executive Officer [Member], USD $)	6 Months Ended
In Millions, except Per Share data, unless otherwise specified	Jun. 30, 2014
Chief Executive Officer [Member]	'
Commitment To Purchase Common Shares [Line Items]	'
Commitment To Purchase Price Per Share	$53.51
Commitment To Purchase Amount	$25

Debt_And_Financing_Arrangement1

Debt And Financing Arrangements (Narrative) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 25, 2014	Jun. 02, 2014	Jun. 30, 2014
			First Amendment [Member]	Bridge Facility [Member]	Bridge Facility [Member]
Line Of Credit Facility [Line Items]	'	'	'	'	'
Maximum borrowing capacity	$700,000,000	'	'	$1,000,000,000	'
Amount outstanding under facility	'	'	'	'	0
Letters of Credit Outstanding, Amount	$216,800,000	$260,300,000	'	'	'
Leverage ratio	'	'	35.00%	'	'
Revised Leverage Ratio	'	'	40.00%	'	'
Debt Instrument Term	'	'	'	'0 years 0 months 364 days	'