Endurance Specialty (ENH) 10-K 27 Feb 15 2014 FY Annual report Financial data

Document_And_Entity_Informatio

Document And Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 20, 2015	Jun. 30, 2014
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Entity Registrant Name	Endurance Specialty Holdings Ltd.
Entity Central Index Key	1179755
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		44,771,673
Entity Public Float			$1,916,453,661

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
ASSETS
Fixed maturity investments, available for sale at fair value (amortized cost: $5,032,506 and $4,802,580 at December 31, 2014 and December 31, 2013, respectively)	$5,092,581	$4,823,964
Short-term investments, available for sale at fair value (amortized cost: $9,015 and $35,029 at December 31, 2014 and December 31, 2013, respectively)	9,014	35,028
Equity securities, available for sale at fair value (cost: $303,922 and $227,828 at December 31, 2014 and December 31, 2013, respectively)	331,368	252,466
Other investments	541,454	617,478
Total investments	5,974,417	5,728,936
Cash and cash equivalents	745,472	845,851
Premiums receivable, net	883,450	669,198
Insurance and reinsurance balances receivable	122,214	127,722
Deferred acquisition costs	207,368	186,027
Prepaid reinsurance premiums	354,940	187,209
Reinsurance recoverable on unpaid losses	670,795	593,755
Reinsurance recoverable on paid losses	218,291	164,220
Accrued investment income	27,183	24,104
Goodwill and intangible assets	153,405	165,378
Deferred tax asset	48,995	51,703
Net receivable on sales of investments	38,877	54,910
Other assets	199,375	179,109
Total assets	9,644,782	8,978,122
LIABILITIES
Reserve for losses and loss expenses	3,846,859	4,002,259
Reserve for unearned premiums	1,254,519	1,018,851
Deposit liabilities	15,136	19,458
Reinsurance balances payable	375,711	181,061
Debt	527,715	527,478
Net payable on purchases of investments	151,682	129,047
Other liabilities	287,978	213,419
Total liabilities	6,459,600	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 - 44,765,153 issued and outstanding (2013 - 44,368,742)	44,765	44,369
Additional paid-in capital	598,226	569,116
Accumulated other comprehensive income	76,706	62,731
Retained earnings	2,448,285	2,193,133
Total shareholders' equity	3,185,182	2,886,549
Total liabilities and shareholders' equity	$9,644,782	$8,978,122

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Available-for-sale Securities [Abstract]
Fixed maturity investments, available for sale, amortized cost	$5,032,506	$4,802,580
Short-term investments, available for sale, amortized cost	9,015	35,029
Equity securities, available for sale, cost	303,922	227,828
Stockholders' Equity, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred shares, Series A and B, total liquidation preference	$430,000	$430,000
Common shares, ordinary, number of shares issued	44,765,153	44,368,742
Common shares, ordinary, number of shares outstanding	44,765,153	44,368,742

Consolidated_Statements_Of_Inc

Consolidated Statements Of Income And Comprehensive Income (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues
Gross premiums written	$2,894,076	$2,665,244	$2,549,026
Ceded premiums written	-959,870	-616,311	-519,531
Net premiums written	1,934,206	2,048,933	2,029,495
Change in unearned premiums	-70,228	-32,449	-15,595
Net premiums earned	1,863,978	2,016,484	2,013,900
Net investment income	131,543	166,216	173,326
Net realized and unrealized gains	14,283	15,164	72,139
Total other-than-temporary impairment losses	-625	-1,616	-364
Portion of loss recognized in other comprehensive income (loss)	0	0	-483
Net impairment losses recognized in earnings	-625	-1,616	-847
Other underwriting loss	-5,786	-2,046	-2,183
Total revenues	2,003,393	2,194,202	2,256,335
Expenses
Net losses and loss expenses	970,162	1,219,684	1,520,995
Acquisition expenses	319,513	304,430	303,179
General and administrative expenses	313,587	294,906	235,689
Amortization of intangibles	6,484	7,012	10,347
Net foreign exchange losses (gains)	3,839	14,214	-15,911
Interest expense	40,968	36,188	36,174
Total expenses	1,654,553	1,876,434	2,090,473
Income before income taxes	348,840	317,768	165,862
Income tax expense	-390	-5,853	-3,346
Net income	348,450	311,915	162,516
Preferred dividends	-32,750	-32,750	-32,750
Net income available to common and participating common shareholders	315,700	279,165	129,766
Comprehensive income
Net income	348,450	311,915	162,516
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 tax (benefit) expense in 2014 - ($4,121); 2013 - $10,613; 2012 - $6,155)	40,150	-95,781	18,916
Foreign currency translation adjustments	-26,264	5,960	3,067
Reclassification adjustment for net losses on derivatives designated as cash flow hedge included in net income	89	89	88
Other comprehensive income (loss)	13,975	-89,732	22,071
Comprehensive income	$362,425	$222,183	$184,587
Per share data
Basic earnings per common share	$7.07	$6.37	$3
Diluted earnings per common share	$7.06	$6.37	$3

Consolidated_Statements_Of_Inc1

Consolidated Statements Of Income And Comprehensive Income (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Deferred income taxes on net unrealized holding gains (losses) on investments	($4,121)	$10,613	$6,155

Consolidated_Statements_Of_Cha

Consolidated Statements Of Changes In Shareholders' Equity (USD $)	Total	Preferred Shares [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Cumulative Foreign Currency Translation Adjustments [Member]	Unrealized Holding Gains (Losses) On Investments, Net Of Deferred Taxes [Member]	Accumulated Derivative Loss On Cash Flow Hedging Instruments [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]
In Thousands
Balance, beginning of year at Dec. 31, 2011		$17,200	$43,087	$526,910	$9,609	$122,815	($2,032)		$1,893,576
Issuance of common shares, net of forfeitures			280	2,820
Repurchase of common shares			-251	-9,754
Settlement of equity awards				-3,272
Stock-based compensation expense				11,211
Foreign currency translation adjustments	3,067				3,067
Net unrealized holding gains (losses) arising during the year, net of other-than-temporary impairment losses and reclassification adjustment	18,916					18,916
Net change from current period hedging transactions, net of reclassification adjustment							88
Net income	162,516								162,516
Dividends on preferred shares	-32,750								-32,750
Dividends on common shares									-53,439
Balance, end of year at Dec. 31, 2012	2,710,597	17,200	43,116	527,915	12,676	141,731	-1,944	152,463	1,969,903
Issuance of common shares, net of forfeitures			1,571	30,480
Repurchase of common shares			-318	-14,266
Settlement of equity awards				-3,001
Stock-based compensation expense				27,988
Foreign currency translation adjustments	5,960				5,960
Net unrealized holding gains (losses) arising during the year, net of other-than-temporary impairment losses and reclassification adjustment	-95,781					-95,781
Net change from current period hedging transactions, net of reclassification adjustment							89
Net income	311,915								311,915
Dividends on preferred shares	-32,750								-32,750
Dividends on common shares									-55,935
Balance, end of year at Dec. 31, 2013	2,886,549	17,200	44,369	569,116	18,636	45,950	-1,855	62,731	2,193,133
Issuance of common shares, net of forfeitures			396	2,143
Repurchase of common shares			0	0
Settlement of equity awards				-4,039
Stock-based compensation expense				31,006
Foreign currency translation adjustments	-26,264				-26,264
Net unrealized holding gains (losses) arising during the year, net of other-than-temporary impairment losses and reclassification adjustment	40,150					40,150
Net change from current period hedging transactions, net of reclassification adjustment							89
Net income	348,450								348,450
Dividends on preferred shares	-32,750								-32,750
Dividends on common shares									-60,548
Balance, end of year at Dec. 31, 2014	$3,185,182	$17,200	$44,765	$598,226	($7,628)	$86,100	($1,766)	$76,706	$2,448,285

Consolidated_Statements_Of_Cas

Consolidated Statements Of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows provided by operating activities:
Net income	$348,450	$311,915	$162,516
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of net premium on investments	45,757	53,336	26,077
Amortization of other intangibles and depreciation	27,234	21,250	22,678
Net realized and unrealized gains	-14,283	-15,164	-72,139
Net impairment losses recognized in earnings	625	1,616	847
Deferred taxes	-1,414	2,412	-5,828
Stock-based compensation expense	31,006	27,988	11,211
Equity in earnings of other investments	-19,608	-64,321	-49,059
Premiums receivable, net	-214,252	-67,246	-57,935
Insurance and reinsurance balances receivable	5,508	-22,059	-12,953
Deferred acquisition costs	-21,341	-17,775	-2,203
Prepaid reinsurance premiums	-167,731	-20,507	-17,032
Reinsurance recoverable on unpaid losses	-77,040	98,028	-223,849
Reinsurance recoverable on paid losses	-54,071	-81,061	115,835
Accrued investment income	-3,079	3,062	2,542
Other assets	-17,132	-10,372	19,464
Reserve for losses and loss expenses	-155,400	-238,617	416,652
Reserve for unearned premiums	235,668	53,607	33,136
Deposit liabilities	-4,322	-2,762	-4,667
Reinsurance balances payable	194,650	70,218	-78,645
Other liabilities	127,036	54,376	-3,180
Net cash flows provided by operating activities	266,261	157,924	283,468
Cash flows (used in) provided by investing activities:
Proceeds from sales of available for sale investments	3,557,450	3,374,002	4,143,528
Proceeds from maturities and calls on available for sale investments	588,490	649,337	943,445
Proceeds from the redemption of other investments	154,655	31,961	79,225
Purchases of available for sale investments	-4,449,225	-4,259,800	-4,964,345
Purchases of other investments	-59,023	-67,572	-115,054
Net settlements of other assets	11,665	-50,355	-15,123
Purchases of fixed assets	-40,932	-24,960	-23,855
Net cash received for subsidiary acquisition	39
Net cash paid for subsidiary acquisition		-390	-1,519
Net cash flows (used in) provided by investing activities	-236,881	-347,777	46,302
Cash flows used in financing activities:
Issuance of common shares	2,305	31,884	2,935
Repurchase of common shares	0	-14,584	-10,005
Settlement of equity awards	-4,039	-3,001	-3,272
Bridge facility costs paid	-4,750	0	0
Proceeds from issuance of debt	706	703	972
Repayments and repurchases of debt	-686	-768	-2,017
Dividends on preferred shares	-32,750	-32,750	-32,750
Dividends on common shares	-60,524	-55,906	-53,439
Net cash flows used in financing activities	-99,738	-74,422	-97,576
Effect of exchange rate changes on cash and cash equivalents	-30,021	-13,893	911
Net (decrease) increase in cash and cash equivalents	-100,379	-278,168	233,105
Cash and cash equivalents, beginning of year	845,851	1,124,019	890,914
Cash and cash equivalents, end of year	$745,472	$845,851	$1,124,019

Organization

Organization	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	1.     Organization
	Endurance Specialty Holdings Ltd. (“Endurance Holdings”) 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. (“Endurance Bermuda”)	Bermuda
	Endurance Worldwide Insurance Limited (“Endurance U.K.”)	England
	Endurance Reinsurance Corporation of America (“Endurance U.S. Reinsurance”)	Delaware
	Endurance American Insurance Company (“Endurance American”)	Delaware
	Endurance American Specialty Insurance Company (“Endurance American Specialty”)	Delaware
	Endurance Risk Solutions Assurance Co. (“Endurance Risk Solutions”)	Delaware
	American Agri-Business Insurance Company (“American Agri-Business”), managed by ARMtech Insurance Services, Inc. (together with American Agri-Business, “ARMtech”)	Texas

Summary_Of_Significant_Account

Summary Of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary Of Significant Accounting Policies	2.     Significant accounting policies
	The consolidated financial statements have been prepared on the basis of accounting principles generally accepted in the United States (“U.S. GAAP”) and include the accounts of Endurance Holdings and its wholly-owned subsidiaries, which are collectively referred to herein as the “Company.” All intercompany transactions and balances have been eliminated in consolidation. The following are significant accounting and reporting policies adopted by the Company:
	(a)	Premiums and related expenses
	The Company’s insurance premiums are earned pro rata over the term of the applicable risk period specified in the insurance policy. The Company’s insurance policies cover losses occurring or claims made during the term of the policy. Generally, the Company receives a fixed premium which is identified in the policy and is recorded on the inception date of the contract or when premiums are determinable and earned evenly over the policy term. This premium will only adjust if the underlying insured values adjust. Accordingly, the Company monitors the underlying insured values and records additional or return premiums in the period in which amounts are reasonably determinable.
	The Company’s reinsurance premiums are earned in proportion to the amount of reinsurance protection provided over the applicable risk period established in the reinsurance contract. Reinsurance contracts written on a losses occurring basis cover losses which occur during the term of the reinsurance contract, typically 12 months. Accordingly, the Company earns the premium on a losses occurring reinsurance contract evenly over the reinsurance contract term. Reinsurance contracts written on a policies attaching basis cover losses from the underlying insurance policies incepting during the terms of the reinsurance contracts. Losses under a policies attaching reinsurance contract may occur after the end date of the reinsurance contract, so long as they are losses from policies that began during the reinsurance contract period. The Company typically earns the premiums for policies attaching reinsurance contracts over a 24-month period in proportion to the amount of reinsurance protection provided to reflect the extension of the risk period past the term of the contract and the varying levels of reinsurance protection provided during the reinsurance contract period.
	In addition to the applicable risk period, the Company’s estimate of its reinsurance premiums written is based on the type of reinsurance contracts underwritten. For excess of loss reinsurance contracts, the deposit premium, as defined in the contract, is generally considered to be the best estimate of the reinsurance contract’s written premium at inception. The Company earns reinstatement premiums upon the occurrence of a loss under the reinsurance contract. Reinstatement premiums are calculated in accordance with the contract terms based upon the ultimate loss estimate associated with each contract. For proportional reinsurance contracts, the Company estimates premium, commissions and related expenses based on broker and ceding company estimates and also utilizes judgment in establishing proportional reinsurance contract estimates.
	2.     Significant accounting policies, cont'd.
	(a)	Premiums and related expenses, cont'd.
	Premiums on the Company’s excess of loss and proportional reinsurance contracts are estimated at the time the business is underwritten. Accordingly, this is the amount the Company records as written premium in the period the reinsurance contract is underwritten. As actual premiums are reported by the ceding companies, management evaluates the appropriateness of the original premium estimates and any adjustments to these estimates are recorded in the period in which they become known.
	Premiums receivable are recorded at amounts due less any allowance for estimated uncollectible premiums receivable. At December 31, 2014, the Company had an allowance for estimated uncollectible premiums receivable of $2.6 million (2013 - $2.3 million).
	Acquisition expenses are costs that vary with and are directly related to the successful production of new and renewal business, and consist principally of commissions and brokerage expenses. Acquisition and general and administrative expenses are shown net of commissions, other fees and expense allowances associated with and earned on ceded business. These costs are deferred and amortized over the periods in which the related premiums are earned. Deferred acquisition costs are limited to their estimated realizable value based on the related unearned premiums. Anticipated net investment income is considered in determining the recoverability of deferred acquisition costs.
	(b)	Reserve for losses and loss expenses
	The Company’s reserve for losses and loss expenses includes case reserves and reserves for losses incurred but not reported (referred to as “IBNR reserves”). Case reserves are established for losses that have been reported, but not yet paid. IBNR reserves represent a provision for claims that have been incurred but not yet reported to the Company, as well as future loss development on losses already reported, in excess of the case reserves. Case reserves and IBNR reserves are established by management based on reports from reinsurance intermediaries, ceding companies and insureds, and consultations with independent legal counsel. In addition, reserves for IBNR losses and loss expenses are established by management based on reported losses and loss expenses, and actuarially determined estimates of ultimate losses and loss expenses.
	The Company uses a variety of actuarial methods to estimate the ultimate losses and loss expenses incurred by the Company. One actuarial method used by the Company to estimate reserves for losses and loss expenses is the expected loss ratio approach, which is based on expected results independent of current loss reporting activity. This approach is typically used for immature loss periods (i.e., the current accident year). Another actuarial method used by the Company to estimate reserves for losses and loss expenses is known as the Bornhuetter-Ferguson method. The Bornhuetter-Ferguson method uses an initial loss estimate (expected loss technique) for each accident year by business line and type of contract. Under this method, IBNR is set equal to the initial loss estimate multiplied by the expected percent of loss yet to be reported at each valuation date. In a given quarter, if reported losses are less than expected, then the difference would result in a decrease in estimated ultimate losses. If losses are greater than expected, then the difference would result in an increase in estimated ultimate losses. A third actuarial method used by the Company to estimate reserves for losses and loss expenses is known as the loss development method. The loss development method extrapolates the current value of reported losses to ultimate expected losses by using selected reporting patterns of losses over time. The selected reporting patterns are based on historical information (organized into loss development triangles) and are adjusted to reflect the changing characteristics of the book of business written by the Company. Management uses these multiple actuarial methods, supplemented with professional judgment, to establish the best estimate of reserves for losses and loss expenses.
	The Company’s loss and loss expense reserves are reviewed regularly, and adjustments, if any, are reflected in earnings in the period in which they become known. The establishment of new loss and loss expense reserves or the adjustment of previously recorded loss and loss expense reserves could result in significant positive or negative changes to the Company’s financial condition for any particular period. While management believes the Company’s estimate of loss and loss expense reserves is reasonable, the ultimate loss experience may not be reliably predicted, and it is possible losses and loss expenses may be materially different than the total reserve for losses and loss expenses recorded by the Company.
	2.     Significant accounting policies, cont'd.
	(c)	Reinsurance
	Reinsurance recoverable on paid and unpaid losses represent estimates of losses and loss expenses that will be recovered from reinsurers. Amounts recoverable from reinsurers are estimated in a manner consistent with the provisions of the reinsurance agreements and consistent with the establishment of the Company’s reserve for losses and loss expenses. Ceding commissions earned on ceded business are classified as an offset to acquisition and general and administrative expenses.
	(d)	Investments
	The Company currently classifies its fixed maturity investments, short-term investments and equity securities as “available for sale” and, accordingly, they are carried at estimated fair value, with related net unrealized gains or losses excluded from earnings and included in shareholders’ equity as a component of accumulated other comprehensive income. Investment transactions are recorded on a trade date basis. The Company determines the fair value of its available for sale investments 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 use of valuation techniques for any given investment requires a significant amount of judgment and consideration of factors specific to the underlying investment. Fair value measurements determined by the Company seek to maximize observable inputs and minimize the use of unobservable inputs. Current accounting guidance establishes three levels as follows:
	Level 1: Unadjusted quoted prices in active markets for identical assets or liabilities.
	Level 2: Quoted prices for similar assets in markets that are active, quoted prices for identical or similar assets in markets that are not active or inputs that are observable either directly or indirectly. Level 2 inputs include quoted prices for similar assets or liabilities other than quoted prices in Level 1; quoted prices in markets that are not active; or other inputs that are observable or can be derived principally from or corroborated by observable market data for substantially the full term of the assets or liabilities.
	Level 3: Unobservable inputs that are supported by little or no market activity and are significant to the fair value of the assets or liabilities. Unobservable inputs reflect the Company’s own views about the assumptions that market participants would use in pricing the asset or liability. Level 3 assets and liabilities include financial instruments whose values are determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant judgment or estimation.
	The Company determines the estimated fair value of each individual security utilizing the highest level inputs available. Transfers between levels are assumed to occur at the end of each period.
	If the Company has the intent to sell a fixed maturity or short-term security in an unrealized loss position or it is more likely than not that the Company will be required to sell the security, the Company deems the security to be other-than-temporarily impaired and writes down the carrying value of the security to fair value, thereby establishing a new cost basis. The amount of the write-down is recognized in earnings as an other-than-temporary impairment (“OTTI”) loss.
	For fixed maturity and short-term investments in an unrealized loss position for which a decision to sell has not been made and it is not more likely than not that the Company will be required to sell the security, the Company performs additional reviews to determine whether the investment will recover its amortized cost.
	If the amortized cost of the Company’s fixed maturity and short-term investments is, based upon the judgment of management, unlikely to be recovered, the Company writes down the investment by the amount representing the credit related portion of the decline in value, thereby establishing a new cost basis. The amount of the write-down is recognized in earnings as an OTTI loss. The new cost basis is not changed for subsequent recoveries in fair value.
	2.     Significant accounting policies, cont'd.
	(d)	Investments, cont'd.
	To the extent the Company determines that the amortized cost of the Company’s fixed maturity and short-term investments is likely to be recovered and the decline in value is related to non-credit factors (such as interest rates, market conditions, etc.) and not due to credit related factors, that remaining non-credit portion of the unrealized loss is recorded as a part of accumulated other comprehensive income in the shareholders’ equity section of the Company’s Consolidated Balance Sheets.
	For equity securities, the Company considers its ability and intent to hold the equity security in an unrealized loss position for a reasonable period of time to allow for a full recovery. When the Company determines that the decline in value of an equity security is other-than-temporary, the Company reduces the cost of the equity security to its fair value and recognizes the loss in the Consolidated Statements of Income and Comprehensive Income. The new cost basis is not changed for subsequent recoveries in fair value.
	Other investments within the Company’s investment portfolio are comprised of (i) hedge funds and private investment funds that generally invest in senior secured bank debt, high yield credit securities, distressed debt, macro strategies, multi-strategy, equity long/short strategies, distressed real estate, and energy sector private equity (“alternative funds”) and (ii) high yield loan funds (“specialty funds”). During 2014, the Company's investment in convertible debt funds previously classified as other investments was merged by the investment manager into a new fund that is classified as an available for sale equity security. Other investments are accounted for using the equity method of accounting whereby the initial investment is recorded at cost. The carrying values of these investments are increased or decreased to reflect the Company’s share of income or loss, which is included in net investment income, and are decreased for dividends. Due to the timing of the delivery of the final valuations reported by the managers of certain of our alternative and specialty funds, our investments in those funds are estimated based on the most recently available information including period end valuation statements, period end estimates, or, in some cases, prior month or quarter valuation statements.
	(e)	Cash equivalents and short-term investments
	Cash equivalents include highly liquid short-term deposits and securities with maturities of ninety days or less at the time of purchase. Cash equivalents are valued at amortized cost, which approximates fair value due to the short-term, liquid nature of these securities. Deposits and securities with maturities greater than ninety days and less than one year are classified as short-term investments.
	(f)	Intangible assets
	Identifiable intangible assets are amortized in accordance with their useful lives. Goodwill and intangible assets with indefinite useful lives are not amortized but are tested for impairment annually or more often if impairment indicators arise. In making an assessment of the value of its goodwill and intangible assets, the Company uses both market based and non-market based valuations.
	Assumptions underlying these valuations include forecasts of discounted future cash flows and future profits in addition to an analysis of the Company’s stock price relative to both its book value and its net income.
	(g)	Offering and registration costs
	Offering and registration costs incurred in connection with equity offerings, including investment banking fees and legal fees, are deducted from the proceeds of the offerings.
	2.     Significant accounting policies, cont'd.
	(h)	Foreign exchange
	Assets and liabilities of foreign operations whose functional currency is not the United States dollar are translated at exchange rates in effect at the balance sheet date. Revenues and expenses of such foreign operations are translated at weighted average exchange rates during the year. The effect of the translation adjustments for foreign operations is included in accumulated other comprehensive income, net of applicable deferred income taxes. Other monetary assets and liabilities denominated in foreign currencies are revalued at the exchange rates in effect at the balance sheet date with the resulting net foreign exchange gains and losses included in earnings. Revenues and expenses denominated in foreign currencies are translated at the prevailing exchange rate on the transaction date.
	(i)	Derivatives
	Current accounting guidance requires the recognition of all derivative financial instruments including embedded derivative instruments, as either assets or liabilities in the Consolidated Balance Sheets at fair value.
	The Company may use various derivative instruments such as foreign exchange forward, future and option contracts; interest rate futures, swaps, swaptions, and options; credit default swaps; commodity futures and options; weather swaps and options; and to-be-announced mortgage-backed securities. Except for a cash flow hedge entered into in 2004 as disclosed in Note 8, these derivative instruments are used to manage exposure to interest rate and currency risk, to enhance the efficiency of the Company’s investment portfolio, to economically hedge certain risks, and as part of its weather risk management business. These derivative instruments do not qualify, and are not designated, as hedges. Thus, changes in fair value and any realized gains or losses are recognized in net realized and unrealized gains, net foreign exchange losses (gains), or other underwriting loss in the Consolidated Statements of Income and Comprehensive Income. Margin balances required of counterparties are included in cash and cash equivalents. Where the Company has entered into master netting agreements with counterparties, or the Company has the legal and contractual right to offset positions, the derivative positions may be netted by the counterparty.
	(j)	Income taxes
	The Company accounts for income taxes for its subsidiaries operating in taxable jurisdictions. Deferred income taxes reflect the net tax effect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. A valuation allowance is provided when it is more likely than not that some portion of the deferred tax assets will not be realized. The accounting guidance allows for the recognition of tax benefits of uncertain tax positions only where the position is more likely than not to be sustained assuming examination by tax authorities. A liability is established for any tax benefit claimed in a tax return in excess of this threshold. Income tax related interest and penalties are included as income tax expense.
	(k)	Stock compensation and other stock plans
	The Company has a share-based employee and non-employee director equity incentive plan (“2007 Equity Incentive Plan”) and other share plans, which are described more fully in Note 15. The fair value of the compensation cost incurred under these plans is measured at the grant date and is expensed over the period for which the employee is required to provide services in exchange for the award. Forfeiture benefits are estimated at the time of grant and incorporated in the determination of share-based compensation costs. Awards under the 2007 Equity Incentive Plan generally vest over four years for employees and one year for non-employee directors.
	2.     Significant accounting policies, cont'd.
	(l)	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 (or accumulated) 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 warrants, 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 warrants and options and the vesting or conversion of all convertible securities such as unvested restricted shares using the two-class method described above.
	(m)	Use of estimates
	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported and disclosed amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
	(n)	Variable interest entity
	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 characteristic 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. See also Note 3.
	(o)	Reclassifications
	Certain comparative information has been reclassified to conform to current year presentation.
	2.     Significant accounting policies, cont'd.
	(p)	Recent accounting pronouncements
	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	12 Months Ended
	Dec. 31, 2014
Investments [Abstract]
Investments	3.     Investments
	Composition of Net Investment Income and of Invested Assets
	The components of net investment income for the years ended December 31, 2014, 2013 and 2012 are as follows:
			2014			2013				2012
	Available for sale investments		$	123,773		$	113,074			$	135,841
	Other investments		19,609			64,321				49,059
	Cash and cash equivalents		2,445			2,752				1,616
			$	145,827		$	180,147			$	186,516
	Investment expenses		(14,284		)	(13,931		)		(13,190		)
	Net investment income		$	131,543		$	166,216			$	173,326
	The following table summarizes the composition of the investment portfolio by investment type at December 31, 2014 and 2013:
			31-Dec-14						31-Dec-13
	Type of Investment		Fair Value			Percentage			Fair Value				Percentage
	Fixed maturity securities		$	5,092,581		77.1	%		$	4,823,964			74.2	%
	Cash and cash equivalents(1)		632,667			9.6	%		771,714				11.9	%
	Other investments(2)		541,454			8.2	%		617,478				9.5	%
	Short-term investments		9,014			0.1	%		35,028				0.5	%
	Equity securities		331,368			5	%		252,466				3.9	%
	Total		$	6,607,084		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 December 31, 2014 and 2013. In some cases, where bonds are unrated, the rating of the issuer has been applied.
			31-Dec-14						31-Dec-13
	Ratings(1)		Fair Value			Percentage			Fair Value				Percentage
	U.S. government and agencies securities		$	587,411		11.5	%		$	769,343			15.8	%
	AAA/Aaa		1,206,252			23.6	%		972,820				20	%
	AA/Aa		1,717,343			33.7	%		1,771,156				36.5	%
	A/A		1,045,301			20.5	%		895,549				18.4	%
	BBB		427,018			8.4	%		363,722				7.5	%
	Below BBB		96,244			1.9	%		66,791				1.4	%
	Not rated		22,026			0.4	%		19,611				0.4	%
	Total		$	5,101,595		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 (“S&P”). If a rating is not supplied by S&P, 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 December 31, 2014 and 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.
			31-Dec-14							31-Dec-13
			Amortized			Fair Value				Amortized				Fair Value
			Cost							Cost
	Due within one year		$	126,921		$	127,821			$	144,814			$	145,653
	Due after one year through five years		1,627,154			1,632,259				1,808,001				1,815,240
	Due after five years through ten years		474,959			479,138				290,391				288,486
	Due after ten years		43,314			46,720				26,344				26,937
	Residential mortgage-backed securities		1,149,536			1,175,006				1,192,085				1,187,191
	Commercial mortgage-backed securities		960,598			979,419				932,263				947,677
	Collateralized loan and debt obligations		247,510			248,011				92,519				94,552
	Asset-backed securities		411,529			413,221				351,192				353,256
	Total		$	5,041,521		$	5,101,595			$	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 securities, distressed debt, macro strategies, multi-strategy, equity long/short strategies, distressed real estate, and energy sector private equity (“alternative funds”) and (ii) high yield loan funds (“specialty funds”). During 2014, the Company's investment in convertible debt funds previously classified as other investments was merged by the investment manager into a new fund that is classified as an available for sale equity security. The Company’s alternative funds and specialty funds are recorded on the Company’s balance sheet as “other investments”. At December 31, 2014 and 2013, the Company had invested, net of capital returned, a total of $387.2 million and $440.9 million, respectively, in other investments. At December 31, 2014 and 2013, the carrying value of other investments was $541.5 million and $617.5 million, respectively. The following table summarizes the composition and redemption restrictions of other investments as of December 31, 2014 and 2013:
	31-Dec-14		Market Value			Unfunded				Ineligible for
						Commitments				Redemption in 2015
	Alternative funds
	Hedge funds		$	411,280		$	—			$	10,580
	Private investment funds		74,664			70,542				74,664
	Total alternative funds		$	485,944		$	70,542			$	85,244
	Specialty funds
	High yield loan funds		$	55,510		$	—			$	—
	Total specialty funds		$	55,510		$	—			$	—
	Total other investments		$	541,454		$	70,542			$	85,244
	31-Dec-13		Market Value			Unfunded				Ineligible for
						Commitments				Redemption in 2014
	Alternative funds
	Hedge funds		$	401,438		$	—			$	47,406
	Private investment funds		59,703			57,997				59,703
Total alternative funds		$	461,141		$	57,997			$	107,109
Specialty funds
High yield loan funds		$	111,254		$	—			$	—
Convertible debt funds		45,083			—				—
Total specialty funds		$	156,337		$	—			$	—
Total other investments		$	617,478		$	57,997			$	107,109
Hedge funds – The redemption frequency of the hedge funds range from monthly to biennially with notice periods from 30 to 90 days. Over one year, it is estimated that the Company can liquidate approximately 97.4% 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 distribution of income or the liquidation of 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 investment 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 Gains
Realized and unrealized gains and losses are recognized in earnings using the first in, first out method. The analysis of net realized and unrealized gains and losses, intangible asset impairment loss, and the change in the fair value of investment-related derivative financial instruments for the years ended December 31, 2014, 2013 and 2012 are as follows:
		2014			2013				2012
Gross realized gains on investment sales		$	35,921		$	40,018			$	77,474
Gross realized losses on investment sales		(16,515		)	(25,521		)		(6,164		)
Intangible asset impairment loss(1)		(5,450		)	—				—
Change in fair value of derivative financial instruments(2)		327			667				829
Net realized and unrealized gains		$	14,283		$	15,164			$	72,139
-1	For additional information on the Company's intangible assets, see Note 10.
-2	For additional information on the Company’s derivative financial instruments, see Note 8.
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 OTTI losses on the Company’s securities classified as available for sale at December 31, 2014 and 2013 are as follows:
31-Dec-14		Amortized			Gross				Gross				Fair Value		Non-Credit
		Cost			Unrealized				Unrealized						OTTI (2)
					Gains				Losses
Fixed maturity investments
U.S. government and agencies securities		$	582,970		$	6,471			$	(2,030	)		$	587,411	$	—
U.S. state and municipal securities		39,340			191				(118		)		39,413		—
Foreign government securities		239,217			2,983				(1,664		)		240,536		—
Government guaranteed corporate securities		47,436			675				(9		)		48,102		—
Corporate securities		1,354,370			12,742				(5,650		)		1,361,462		—
Residential mortgage-backed securities		1,149,536			27,542				(2,072		)		1,175,006		(3,233		)
Commercial mortgage-backed securities		960,598			21,374				(2,553		)		979,419		(5		)
Collateralized loan and debt obligations(1)		247,510			1,449				(948		)		248,011		—
Asset-backed securities		411,529			2,265				(573		)		413,221		—
Total fixed maturity investments		$	5,032,506		$	75,692			$	(15,617	)		$	5,092,581	$	(3,238	)
Short-term investments		9,015			—				(1		)		9,014		—
Total fixed income investments		$	5,041,521		$	75,692			$	(15,618	)		$	5,101,595	$	(3,238	)
Equity securities
Equity investments		$	176,167		$	29,660			$	(3,292	)		$	202,535	$	—
Emerging market debt funds		60,826			—				(676		)		60,150		—
Convertible funds		46,331			—				(220		)		46,111		—
Preferred equity investments		13,858			2,022				(44		)		15,836		—
Short-term fixed income fund		6,740			—				(4		)		6,736		—
Total equity securities		$	303,922		$	31,682			$	(4,236	)		$	331,368	$	—
-1	Balances include amounts related to collateralized debt obligations held with total fair values of $15.2 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, 2014, the gross unrealized loss related to fixed income investments for which a non-credit OTTI was recognized in accumulated other comprehensive income was nil.
3.     Investments, cont'd.
December 31, 2013		Amortized			Gross				Gross				Fair Value		Non-Credit
		Cost			Unrealized				Unrealized						OTTI (2)
					Gains				Losses
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 fund		8,728			2				—				8,730		—
Total equity securities		$	227,828		$	26,712			$	(2,074	)		$	252,466	$	—
-1	Balances include amounts related to collateralized debt obligations held with total fair values of $18.7 million.
-2	Represents total OTTI recognized in accumulated other comprehensive income. It does not include the change in fair value subsequent to the impairment measurement date. At December 31, 2013, the gross unrealized loss related to fixed income investments for which a non-credit OTTI was recognized in accumulated other comprehensive income was $0.1 million.
3.     Investments, cont'd.
The following tables summarize, for all available for sale securities in an unrealized loss position at December 31, 2014 and 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
31-Dec-14		Unrealized			Fair				Unrealized				Fair		Unrealized			Fair
		Losses(1)			Value				Losses(1)				Value		Losses(1)			Value
Fixed maturity investments
U.S. government and agencies securities		$	(481	)	$	155,350			$	(1,549	)		$	45,993	$	(2,030	)	$	201,343
U.S. state and municipal securities		(47		)	3,295				(71		)		6,841		(118		)	10,136
Foreign government securities		(1,378		)	37,904				(286		)		4,306		(1,664		)	42,210
Government guaranteed corporate securities		(9		)	4,598				—				—		(9		)	4,598
Corporate securities		(4,023		)	533,139				(1,627		)		84,278		(5,650		)	617,417
Residential mortgage-backed securities		(260		)	62,832				(1,812		)		108,899		(2,072		)	171,731
Commercial mortgage-backed securities		(1,068		)	180,222				(1,485		)		78,412		(2,553		)	258,634
Collateralized loan and debt obligations		(876		)	176,439				(72		)		6,491		(948		)	182,930
Asset-backed securities		(415		)	199,205				(158		)		19,095		(573		)	218,300
Total fixed maturity investments		$	(8,557	)	$	1,352,984			$	(7,060	)		$	354,315	$	(15,617	)	$	1,707,299
Short-term investments		(1		)	1,953				—				—		(1		)	1,953
Total fixed income investments		$	(8,558	)	$	1,354,937			$	(7,060	)		$	354,315	$	(15,618	)	$	1,709,252
Equity securities
Equity investments		$	(3,292	)	$	53,591			$	—			$	—	$	(3,292	)	$	53,591
Emerging market debt funds		(676		)	60,150				—				—		(676		)	60,150
Convertible funds		(220		)	46,111				—				—		(220		)	46,111
Preferred equity investments		(44		)	4,449				—				—		(44		)	4,449
Short-term fixed income fund		(4		)	6,736				—				—		(4		)	6,736
Total equity securities		$	(4,236	)	$	171,037			$	—			$	—	$	(4,236	)	$	171,037
-1	Gross unrealized losses include unrealized losses on non-OTTI and non-credit OTTI securities recognized in accumulated other comprehensive income at December 31, 2014.
As of December 31, 2014, 747 available for sale securities were in an unrealized loss position aggregating $19.9 million. Of those, 171 securities with aggregated unrealized losses of $7.1 million at December 31, 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
December 31, 2013		Unrealized			Fair				Unrealized				Fair		Unrealized			Fair
		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 at December 31, 2013 had been in a continuous unrealized loss position for twelve months or greater.
The analysis of OTTI for the years ended December 31, 2014, 2013 and 2012 is as follows:
		2014			2013				2012
Total other-than-temporary impairment losses		$	(625	)	$	(1,616	)		$	(364	)
Portion of loss recognized in other comprehensive income (loss)		—			—				(483		)
Net impairment losses recognized in earnings		$	(625	)	$	(1,616	)		$	(847	)
3.     Investments, cont'd.
Of the $0.6 million (2013 - $1.6 million; 2012 - $0.8 million) of OTTI losses recognized by the Company for the year ended December 31, 2014, the majority was related to reductions in expected recovery values on mortgage-backed securities during the period, and expected losses on corporate securities following the Company’s decision to liquidate a specific portfolio. The unrealized losses on the Company’s fixed income securities at December 31, 2014 were primarily due to an increase in interest rates and widening of credit spreads, rather than any actual credit losses on these securities. At December 31, 2014, the Company did not have the intent to sell any of the remaining fixed maturity 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 these securities to be other-than-temporarily impaired at December 31, 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 years ended December 31, 2014, 2013 and 2012 :
		2014			2013				2012
Beginning balance		$	(1,553	)	$	(2,000	)		$	(2,225	)
Addition for the amount related to the credit loss for which an other-than-temporary impairment was not previously recognized		—			—				(3		)
Addition for the amount related to the credit loss for which an other-than-temporary impairment was previously recognized		—			—				(502		)
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 year		715			447				730
Ending balance		$	(838	)	$	(1,553	)		$	(2,000	)
Variable Interest Entities
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 December 31, 2014 and 2013. 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 Consolidated Balance Sheets and any unfunded investment commitments.

Fair_Value_Measurement

Fair Value Measurement	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurement	4.     Fair value measurement
	The Company determines the fair value of the fixed maturity investments, short-term investments, equity securities, other investments, debt, and other assets and liabilities in accordance with current accounting guidance, which defines fair value and establishes a fair value hierarchy based on inputs to the various valuation techniques used for each fair value measurement. The Company determines the estimated fair value of each individual security utilizing the highest level inputs available. Valuation inputs by security type may include the following:
	•	Government and agencies fixed maturity securities – These securities are generally priced by pricing services or index providers. The pricing services or index providers may use current market trades for securities with similar quality, maturity and coupon. If no such trades are available, the pricing service typically uses analytical models which may incorporate option adjusted spreads, daily interest rate data and market/sector news. The Company generally classifies the fair values of government and agencies securities in Level 2. Current issue U.S. government securities are generally valued based on Level 1 inputs, which use the market approach valuation technique.
	4.     Fair value measurement, cont'd.
	•	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 credit 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, 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.
	4.     Fair value measurement, cont'd.
	•	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 December 31, 2014 and 2013.
	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, 2014:
						Fair Value Measurements at December 31, 2014
			Total at December 31, 2014			Quoted			Significant			Significant
						Prices in			Other			Unobservable
						Active			Observable			Inputs
						Markets for			Inputs			(Level 3)
						Identical			(Level 2)
						Assets
						(Level 1)
	Assets
	Fixed maturity investments
	U.S. government and agencies securities		$	587,411		$	105,121		$	482,290		$	—
	U.S. state and municipal securities		39,413			—			39,413			—
	Foreign government securities		240,536			—			240,536			—
	Government guaranteed corporate securities		48,102			—			48,102			—
	Corporate securities		1,361,462			—			1,358,960			2,502
	Residential mortgage-backed securities		1,175,006			—			1,174,997			9
	Commercial mortgage-backed securities		979,419			—			974,602			4,817
	Collateralized loan and debt obligations		248,011			—			246,042			1,969
	Asset-backed securities		413,221			—			410,228			2,993
	Total fixed maturity investments		$	5,092,581		$	105,121		$	4,975,170		$	12,290
	Equity securities
	Equity investments		202,535			138,463			64,072			—
	Emerging market debt funds		60,150			—			60,150			—
	Convertible funds		46,111			—			46,111			—
	Preferred equity investments		15,836			—			15,836			—
	Short-term fixed income fund		6,736			6,736			—			—
	Total equity securities		$	331,368		$	145,199		$	186,169		$	—
	Short-term investments		9,014			—			9,014			—
	Other investments		541,454			—			—			541,454
	Other assets (see Note 8)		99,504			—			73,889			25,615
	Total assets		$	6,073,921		$	250,320		$	5,244,242		$	579,359
	Liabilities
	Other liabilities (see Note 8)		$	54,338		$	—		$	18,972		$	35,366
	Debt		623,740			—			623,740			—
	Total liabilities		$	678,078		$	—		$	642,712		$	35,366
	4.     Fair value measurement, cont'd.
	During 2014, $13.3 million of primarily commercial and residential mortgage-backed securities and corporate securities were transferred into Level 3 as no observable inputs were available, and $7.5 million of primarily commercial and residential mortgage-backed securities and collateralized loan and debt obligations were transferred out of Level 3 as market activity for these securities increased and observable inputs became available. During the year ended December 31, 2014, $6.6 million of U.S. government and agencies securities were transferred from Level 1 to Level 2 as they no longer qualified as on the run U.S. treasury securities.
	The following table sets forth the Company’s available for sale investments, other investments, other assets and liabilities and debt categorized by the level within the hierarchy in which the fair value measurements fall at December 31, 2013:
						Fair Value Measurements at December 31, 2013
			Total at December 31, 2013			Quoted			Significant			Significant
						Prices in			Other			Unobservable
						Active			Observable			Inputs
						Markets for			Inputs			(Level 3)
						Identical			(Level 2)
						Assets
						(Level 1)
	Assets
	Fixed maturity investments
	U.S. government and agencies securities		$	769,343		$	20,248		$	749,095		$	—
	U.S. state and municipal securities		26,854			—			26,854			—
Foreign government securities		182,647			—			182,647			—
Government guaranteed corporate securities		35,145			—			35,145			—
Corporate securities		1,227,299			—			1,226,553			746
Residential mortgage-backed securities		1,187,191			—			1,186,943			248
Commercial mortgage-backed securities		947,677			—			946,794			883
Collateralized loan and debt obligations		94,552			—			92,095			2,457
Asset-backed securities		353,256			—			350,262			2,994
Total fixed maturity investments		$	4,823,964		$	20,248		$	4,796,388		$	7,328
Equity securities
Equity investments		174,669			117,776			56,893			—
Emerging market debt funds		60,844			—			60,844			—
Preferred equity investments		8,223			—			8,223			—
Short-term fixed income fund		8,730			8,730			—			—
Total equity securities		$	252,466		$	126,506		$	125,960		$	—
Short-term investments		35,028			—			35,028			—
Other investments		617,478			—			—			617,478
Other assets (see Note 8)		108,272			—			94,234			14,038
Total assets		$	5,837,208		$	146,754		$	5,051,610		$	638,844
Liabilities
Other liabilities (see Note 8)		$	49,452		$	—		$	29,883		$	19,569
Debt		575,115			—			575,115			—
Total liabilities		$	624,567		$	—		$	604,998		$	19,569
4.     Fair value measurement, cont'd.
Level 3 assets represented 9.5% and 10.9% of the Company’s total available for sale investments, other investments and derivative instruments at December 31, 2014 and 2013, respectively. Level 3 securities are primarily comprised of corporate securities, non-agency commercial mortgage-backed securities, asset-backed securities, collateralized debt obligations, investments in alternative and specialty funds, and weather derivatives. The NAV used to measure the fair value 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 year ended December 31, 2014.
Other assets and other liabilities measured at fair value include assets of $25.6 million (2013 - $14.0 million) and liabilities of $35.4 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:
•	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 transactions 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.
4.     Fair value measurement, cont'd.
Below is a summary of quantitative information regarding the significant observable and unobservable inputs used in determining the fair value of the net weather and energy related derivative liabilities classified in Level 3 that are measured at fair value on a recurring basis at December 31, 2014 and 2013:
		31-Dec-14
		Fair Value			Valuation		Unobservable	Low			High			Weighted Average
		(Level 3)			Techniques		Inputs							or Actual
		(U.S. dollars in thousands, except for correlation and commodity curve)
Net weather and energy related derivative liabilities		$	9,751		Historical		Correlation	0			1			Actual
					Analysis and
					Simulation
							Weather curve	$	(828	)	$	2,500		Actual
							Commodity curve	$	—		$	—		Actual
		December 31, 2013
		Fair Value (Level 3)			Valuation Techniques		Unobservable	Low			High			Weighted Average
							Inputs							or Actual
		(U.S. dollars in thousands, except for correlation and commodity curve)
Net weather and energy related derivative liabilities		$	5,531		Historical Analysis and Simulation		Correlation	0			1			Actual
							Weather curve	$	—		$	7,940		Actual
							Commodity curve	$	0.65		$	10		Actual
There were no impairment losses on Level 3 securities recognized in earnings for the year ended December 31, 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 years ended December 31, 2014 and 2013.
31-Dec-14		Fixed			Other			Other			Total			Other
		maturity			investments			assets			assets			liabilities
		investments
Level 3, beginning of year		$	7,328		$	617,478		$	14,038		$	638,844		$	(19,569	)
Total equity income and realized gains included in earnings		144			58,555			—			58,699			—
Total equity losses and losses included in earnings		(85		)	(38,947		)	—			(39,032		)	—
Total income included in other underwriting loss		—			—			32,642			32,642			29,040
Total loss included in other underwriting loss		—			—			(27,147		)	(27,147		)	(37,617		)
Change in unrealized gains included in other comprehensive income (loss)		801			—			—			801			—
Change in unrealized losses included in other comprehensive income (loss)		(706		)	—			—			(706		)	—
Purchases		842			59,023			2,807			62,672			(1,404		)
Issues		—			—			15,631			15,631			(25,692		)
Sales		(1,848		)	(154,655		)	—			(156,503		)	—
Settlements		—			—			(12,356		)	(12,356		)	19,876
Transfers into Level 3		13,311			—			—			13,311			—
Transfers out of Level 3		(7,497		)	—			—			(7,497		)	—
Level 3, end of year		$	12,290		$	541,454		$	25,615		$	579,359		$	(35,366	)
4.     Fair value measurement, cont'd.
31-Dec-13		Fixed			Other			Other			Total			Other
		maturity			investments			assets			assets			liabilities
		investments
Level 3, beginning of year		$	8,497		$	517,546		$	882		$	526,925		$	(1,922	)
Total equity income and realized gains included in earnings		127			86,605			—			86,732			—
Total equity losses and losses included in earnings		(17		)	(22,284		)	—			(22,301		)	—
Total income included in other underwriting loss		—			—			10,452			10,452			7,340
Total loss included in other underwriting loss		—			—			(6,927		)	(6,927		)	(11,126		)
Change in unrealized gains included in other comprehensive income (loss)		749			—			—			749			—
Change in unrealized losses included in other comprehensive income (loss)		(305		)	—			—			(305		)	—
Purchases		1,665			67,571			2,994			72,230			(587		)
Issues		—			—			6,637			6,637			(13,274		)
Sales		(6,654		)	(31,960		)	—			(38,614		)	—
Transfers into Level 3		11,729			—			—			11,729			—
Transfers out of Level 3		(8,463		)	—			—			(8,463		)	—
Level 3, end of year		$	7,328		$	617,478		$	14,038		$	638,844		$	(19,569	)

Reserve_For_Losses_And_Loss_Ex

Reserve For Losses And Loss Expenses	12 Months Ended
	Dec. 31, 2014
Insurance Loss Reserves [Abstract]
Reserve For Losses And Loss Expenses	5.     Reserve for losses and loss expenses
	Activity in the reserve for losses and loss expenses for the years ended December 31, 2014, 2013 and 2012 is summarized as follows:
		2014			2013			2012
	Gross reserve for losses and loss expenses, January 1	$	4,002,259		$	4,240,876		$	3,824,224
	Reinsurance recoverable on unpaid losses	593,755			691,783			467,934
	Net reserve for losses and loss expenses, January 1	3,408,504			3,549,093			3,356,290
	Incurred related to:
	Current year	1,203,977			1,442,076			1,641,152
	Prior years	(233,815		)	(222,392		)	(120,157		)
	Total incurred	970,162			1,219,684			1,520,995
	Paid related to:
	Current year	(439,169		)	(524,010		)	(608,228		)
	Prior years	(719,043		)	(838,082		)	(715,528		)
	Total paid	(1,158,212		)	(1,362,092		)	(1,323,756		)
	Foreign currency translation and other	(44,390		)	1,819			(4,436		)
	Net reserve for losses and loss expenses, December 31	3,176,064			3,408,504			3,549,093
	Reinsurance recoverable on unpaid losses	670,795			593,755			691,783
	Gross reserve for losses and loss expenses, December 31	$	3,846,859		$	4,002,259		$	4,240,876
	5.     Reserve for losses and loss expenses, cont'd.
	During 2014, the Company’s estimated ultimate losses for prior accident years were reduced by $233.8 million (2013 – $222.4 million; 2012 – $120.2 million) due to lower claims emergence than originally estimated by the Company. During 2014, the Company experienced favorable development in the Reinsurance segment of $153.2 million across each line of business. In the Insurance segment, the Company experienced $80.6 million of favorable development across each line of business. During 2013, the Company experienced favorable development in the Reinsurance segment of $188.5 million across each line of business. In the Insurance segment, the Company experienced $33.9 million of favorable development across each line of business. During 2012, the Company experienced favorable development in the Reinsurance segment of $74.0 million in the catastrophe, casualty, professional lines and specialty lines of business. In the Insurance segment, the Company experienced $46.2 million of favorable development across each line of business.
	Reserves for losses and loss expenses are based in part upon the estimation of losses resulting from catastrophic events. Estimation of these losses and loss expenses are based upon the Company’s historical claims experience and is inherently difficult because of the Company’s short operating history and the possible severity of catastrophe claims. Therefore, the Company uses both proprietary and commercially available models, as well as historical reinsurance industry catastrophe claims experience in addition to its own historical data for purposes of evaluating trends and providing an estimate of ultimate claims costs.
	A significant portion of the Company’s contracts and policies cover excess layers for high severity exposures. Underwriting results and ultimate claims payments for this type of coverage are therefore not typically reported to the Company until later in the contract and policy lives. As a result, the level of losses reported to date is not necessarily indicative of expected future results.

Reinsurance

Reinsurance	12 Months Ended
	Dec. 31, 2014
Reinsurance Disclosures [Abstract]
Reinsurance	6.     Reinsurance
	The effects of reinsurance on premiums earned and written during the years ended December 31, 2014, 2013 and 2012 are as follows:
		Year Ended December 31, 2014						Year Ended December 31, 2013						Year Ended December 31, 2012
		Earned			Written			Earned			Written			Earned			Written
	Direct	$	1,521,648		$	1,716,128		$	1,472,796		$	1,475,429		$	1,428,765		$	1,429,930
	Assumed	1,132,370			1,177,948			1,139,487			1,189,815			1,087,702			1,119,096
	Ceded	(790,040		)	(959,870		)	(595,799		)	(616,311		)	(502,567		)	(519,531		)
		$	1,863,978		$	1,934,206		$	2,016,484		$	2,048,933		$	2,013,900		$	2,029,495
	The Company purchases reinsurance to reduce its exposure to risk of loss in certain insurance and reinsurance lines of business. Reinsurance recoverables are recorded as assets if the reinsurer is deemed able to meet its obligations. Ceded reinsurance contracts do not relieve the Company from its obligations to policyholders. The Company remains primarily liable to its policyholders for the portion reinsured to the extent that any reinsurer does not meet the obligations assumed under the reinsurance agreements.
	6.     Reinsurance, cont'd.
	During the year ended December 31, 2014, the Company recorded ceded losses of $575.7 million (2013 - $683.2 million; 2012 - $737.8 million). The balance of reinsurance recoverable on paid and unpaid losses at December 31, 2014 and 2013 was distributed as follows based on the ratings of the reinsurers:
	Rating	31-Dec-14			31-Dec-13
	U.S. government sponsored program	$	339,617		$	356,049
	A+ and above	294,216			253,665
	A	248,297			135,949
	A- and below	4			2,046
	Not rated	6,952			10,266
	Total	$	889,086		$	757,975
	At December 31, 2014 and 2013, the Company held collateral of $199.7 million and $14.2 million, respectively, related to its ceded reinsurance agreements.

Debt_And_Financing_Arrangement

Debt And Financing Arrangements	12 Months Ended
	Dec. 31, 2014
Debt Instruments [Abstract]
Debt And Financing Arrangements	7.     Debt and financing arrangements
	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”). Upon entering into the Credit Facility, the Company terminated its existing $1,175.0 million amended and restated credit agreement dated May 8, 2007 with JPMorgan as administrative agent. As of December 31, 2014 and 2013, there were no borrowings under the Credit Facility and letters of credit outstanding under the Credit Facility were $204.0 million and $260.3 million, respectively.
	The Credit Facility consists of two tranches: (i) a tranche 1 secured credit facility in an aggregate principal amount of $560.0 million (the “Tranche 1 Facility”), which is secured on a several basis by the respective entity incurring such obligation by cash and securities deposited into collateral accounts from time to time with Deutsche Bank Trust Company Americas and (ii) a tranche 2 unsecured facility in an aggregate principal amount of $140.0 million (the “Tranche 2 Facility”). The proceeds of the Credit Facility may be used for general corporate purposes, to finance potential acquisitions and for the repurchase of the Company’s outstanding publicly or privately issued securities. So long as the Company is not in default under the terms of the Credit Facility, the Company may request that the size of the Credit Facility be increased by $350.0 million, provided that no participating lender is obligated to increase its commitments under the Credit Facility.
	For letters of credit issued on a collateralized basis under the Tranche 1 Facility, the Company is required to pay a fee of 0.45% on the daily stated amount of such letters of credit. For letters of credit issued on an uncollateralized basis under the Tranche 2 Facility, the Company is required to pay a fee ranging from 1.125% to 1.750% over LIBOR on the daily stated amount of such letters of credit based upon the Company’s debt ratings as issued by Moody’s or S&P. The interest rate for revolving loans under the Tranche 2 Facility is (a) the highest of (i) 0.5% in excess of the federal funds effective rate, (ii) the prime rate as announced by JP Morgan and (iii) the Eurodollar rate applicable for an interest period of one month plus 1%, plus a margin ranging from 0.125% to 0.750% depending upon the type of loan and the Company’s ratings as issued by Moody’s and S&P or (b) LIBOR plus a margin ranging from 1.125% to 1.750%. In addition, the Credit Facility required the Company to pay to the lenders a commitment fee.
	The Credit Facility requires the Company’s compliance with certain customary restrictive covenants. These include certain financial covenants, such as maintaining a leverage ratio (no greater than 0.35:1.00 at any time) and a consolidated tangible net worth (no less than $1.8 billion at any time). In addition, each of the Company’s regulated insurance subsidiaries that has a claims paying rating from A.M. Best must maintain a rating of at least B++ at all times. The terms of the Credit Facility restrict the declaration or payment of dividends if the Company is already in default or the payment or declaration would cause a default under the terms of the Credit Facility.
	7.     Debt and financing arrangements, cont'd.
	The Credit Facility also contains customary event of default provisions, including failure to pay principal or interest under the Credit Facility, insolvency of the Company, a change in control of the Company, a breach of the Company’s representations or covenants in the Credit Facility or a default by the Company under its other indebtedness. Upon the occurrence of an event of default under the Credit Facility, the lenders can terminate their commitments under the Credit Facility, require repayment of any outstanding revolving loans, give notice of termination of any outstanding letters of credit in accordance with their terms, require the delivery of cash collateral for outstanding letters of credit and foreclose on any security held by the lenders under the Credit Facility.
	On June 25, 2014, the Company entered into the First Amendment (the “Amendment”) to the Credit Facility. The Amendment also amends the Security Agreement, dated as of April 19, 2012 (the “Security Agreement”), among the Company and various designated subsidiaries of the Company, Deutsche Bank Trust Company America, as collateral agent, and JPMorgan. The Amendment contained certain amendments to the Credit Facility and the Security Agreement applicable to the proposed acquisition of Aspen Insurance Holdings Limited (“Aspen”).
	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 December 31, 2014, the Company had issued letters of credit of $5.9 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.
	On December 9, 2014, the Company and certain designated subsidiaries of the Company entered into a $30.0 million Canadian dollar letter of credit reimbursement agreement ("Canadian LOC Agreement") with Bank of Montreal and ING Bank N.V., London Branch. As of December 31, 2014, there were no letters of credit issued under the Canadian LOC Agreement. For letters of credit issued under the Canadian LOC Agreement, the Company is required to pay a fee on the daily amount available to be drawn under each letter of credit. Letters of credit issued under the Canadian LOC Agreement are required to be collateralized with cash in Canadian dollars.
	On June 2, 2014, the Company entered into a commitment letter with Morgan Stanley Senior Funding, Inc. (the “Commitment Letter”). Pursuant to the Commitment Letter, Morgan Stanley Senior Funding, Inc., as lead arranger, committed to provide to the Company, subject to certain conditions, senior unsecured bank financing of up to $1.0 billion under an unsecured 364-day bridge facility (the “Bridge Facility”), which was to be used to finance a portion of the cash consideration to be paid in connection with the Company’s proposed acquisition of Aspen and related costs and expenses. Upon the termination by the Company of its offer to acquire Aspen on July 30, 2014, the Bridge Facility expired pursuant to its terms.
	On March 23, 2010, the Company issued an additional $85.0 million principal amount of 7% Senior Notes due July 15, 2034 (the “7% Senior Notes”), $250.0 million of which were initially issued on July 15, 2004 at a price of 94.976% of their principal amount, providing an effective yield to investors of 7.449%. On the closing of the additional issuance, the Company had a total par value of $335.0 million of the 7% Senior Notes outstanding. The additional 7% Senior Notes issued have terms identical to the previously issued notes in the series, other than the date of issue, the initial purchase price to the public and the first interest payment date. The additional 7% Senior Notes trade interchangeably with and vote together with the previously issued 7% Senior Notes. The Company used the proceeds from the additional 7% Senior Notes for general corporate purposes.
	On October 17, 2005, Endurance Holdings issued $200.0 million principal amount of 6.15% Senior Notes due 2015 (the “6.15% Senior Notes”). The 6.15% Senior Notes were offered by the underwriters at a price of 99.639% of their principal amount, providing an effective yield to investors of 6.199%, and, unless previously redeemed, will mature on October 15, 2015. Endurance Holdings used the net proceeds from the offering to repay the $143.5 million then outstanding under Endurance Holdings’ revolving credit facility as well as to provide additional capital to its subsidiaries and for other general corporate purposes.
	The 6.15% Senior Notes and the 7% Senior Notes (collectively, the “Senior Notes”) are senior unsecured obligations of Endurance Holdings and rank equally with all of Endurance Holdings’ existing and future unsecured and unsubordinated debt. The Senior Notes are also effectively junior to claims of creditors of Endurance Holdings’ subsidiaries, including policyholders, trade creditors, debt holders, and taxing authorities.
	7.     Debt and financing arrangements, cont'd.
	The indentures governing each of the Senior Notes contain customary covenants and events of default for senior unsecured indebtedness, including events of default for non-payment of principal or interest, breaches of covenants, insolvency of the Company or a default by the Company under other outstanding indebtedness. The Company was in compliance with all covenants contained within the indentures governing the Senior Notes as of December 31, 2014.
	The Company made aggregate interest payments of $40.4 million during the year ended December 31, 2014 (2013 - $35.7 million, 2012 - $35.7 million). Aggregate interest payments during the year ended December 31, 2014 include $4.8 million of costs on the Bridge Facility, as described above.

Derivatives

Derivatives	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	8.     Derivatives
	In 2004, prior to the issuance of the 7% Senior Notes, the Company entered into an interest rate lock on a notional amount of $125.0 million to protect against interest rate increases before the anticipated issuance of the Senior Notes. The objective of the interest rate lock was to protect 50% of the forecasted receipt of proceeds from the issuance of the 7% Senior Notes offering, which was subject to change prior to issuance due to fluctuations in the benchmark 30 year U.S. Treasury rate. Upon issuance of the 7% Senior Notes, the interest rate lock was settled through payment by the Company of $2.7 million. The interest rate lock agreement was designated as a “cash flow hedge” under current accounting guidance and accordingly, the fair value of the derivative was recorded in other comprehensive income (loss) and is being recognized as a component of interest expense in the Consolidated Statements of Income and Comprehensive Income as the interest expense related to the 7% Senior Notes affects earnings. The net income effect of the interest rate lock was not material.
	The Company regularly transacts in certain derivative-based weather risk management products primarily to address weather and energy risks. The trading 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.
	None of the Company’s derivatives are designated as hedges under current accounting guidance, with the exception of the interest rate lock. The Company invests a portion of its fixed maturity assets with a third party investment manager 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 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 its 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 the overall investment strategy. TBAs represent commitments to purchase or sell a future issuance of agency mortgage-backed securities. For the period between the 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.
	8.     Derivatives, cont'd.
	The fair values and the related notional values of derivatives at December 31, 2014 and 2013 are noted below.
		31-Dec-14						31-Dec-13
		Fair			Notional			Fair			Notional
		Value			Principal			Value			Principal
					Amount						Amount
	Derivatives recorded in other assets
	Foreign exchange forward contracts	$	651		$	42,694		$	251		$	19,269
	Interest rate swaps	—			—			124			16,100
	Interest rate swaptions	—			—			39			24,338
	Interest rate futures	7			7,595			—			—
	TBAs	73,231			70,000			93,820			93,840
	Energy and weather contracts	25,615			81,624			14,038			53,986
	Total recorded in other assets	$	99,504					$	108,272
	Derivatives recorded in other liabilities
	Foreign exchange forward contracts	$	123		$	20,945		$	172		$	15,861
	Interest rate swaps	20			12,549			933			12,193
	Interest rate swaptions	9			13,100			543			361,455
	Interest rate futures	—			—			17			103,935
	TBAs	18,820			18,000			28,218			28,000
	Energy and weather contracts	35,366			135,050			19,569			66,113
	Total recorded in other liabilities	$	54,338					$	49,452
	Net derivative asset	$	45,166					$	58,820
	At December 31, 2014, derivative assets of $99.5 million (December 31, 2013 - $14.5 million) and liabilities of $54.3 million (December 31, 2013 - $21.2 million) were subject to master netting agreements, which provide for the ability to settle the derivative asset and liability with each counterparty on a net basis. At December 31, 2014, interest rate futures were not subject to master netting agreements. At December 31, 2013, TBAs and interest rate futures were not subject to master netting agreements. At December 31, 2014 and 2013, none of the Company’s derivative instruments were recorded on a net basis in the Consolidated Balance Sheets.
	The gains and losses on the Consolidated Statements of Income and Comprehensive Income for derivatives for the years ended December 31, 2014 and 2013 were as follows:
		2014			2013			2012
	Total included in net foreign exchange losses (gains) from foreign exchange forward contracts	$	1,880		$	357		$	98
	Interest rate futures	$	121		$	44		$	87
	Credit default swaps	30			49			48
	Interest rate swaps	(4,239		)	1,241			85
	Interest rate swaptions	477			291			29
	TBAs	3,938			(958		)	580
	Total included in net realized and unrealized gains	$	327		$	667		$	829
	Energy and weather contracts	$	(315	)	$	(261	)	$	—
	Commodity put options	—			—			(2,684		)
	Total included in other underwriting loss	$	(315	)	$	(261	)	$	(2,684	)
	Total gains from derivatives	$	1,892		$	763		$	(1,757	)

Segment_Reporting

Segment Reporting	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Segment Reporting	9.     Segment reporting
	The determination of the Company’s business segments is based on how the Company monitors the performance of its underwriting operations. The Company has two reportable business segments, Insurance and Reinsurance.
	•	Insurance – This segment is comprised of four lines of business: agriculture, casualty and other specialty, professional lines, and property, marine and energy. The agriculture line of business is comprised of multi-peril crop insurance, crop hail, livestock risk protection and other agriculture risk management products. The casualty and other specialty line of business is comprised of the insurance and facultative reinsurance of third party liability exposures, including casualty and healthcare liability. The professional line of business includes directors’ and officers’ liability, errors and omissions, employment practices liability, environmental liability and pension trust liability insurance. The property, marine and energy line of business is comprised of the insurance and facultative reinsurance of commercial properties, inland marine and ocean marine insurance, and energy insurance.
	•	Reinsurance – This segment is comprised of five lines of business: catastrophe, property, casualty, professional lines, and specialty. The catastrophe line of business includes reinsurance for catastrophic perils on a treaty basis. The property line of business includes proportional and excess of loss reinsurance of personal and commercial exposures. The casualty line of business is comprised of third party liability exposures, clash and workers’ compensation coverages. The professional line of business includes directors’ and officers’ liability, errors and omissions, employment practices liability, environmental liability and pension trust liability reinsurance. The specialty line of business includes the reinsurance of aviation and space business and proportional and non-proportional reinsurance of hull and cargo insurance business, and proportional and excess of loss coverages of contract and commercial surety business, personal accident coverages, political risk coverages, weather risk management products and agriculture coverages for weather related perils as well as protection from yield and price risks.
	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 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.
	9.     Segment reporting, cont'd.
	The following table provides a summary of the segment revenues and results for the year ended December 31, 2014, reserve for losses and loss expenses as of December 31, 2014 and the carrying value of goodwill as of December 31, 2014:
			Insurance			Reinsurance			Total
	Revenues
	Gross premiums written		$	1,716,128		$	1,177,948		$	2,894,076
	Ceded premiums written		(855,722		)	(104,148		)	(959,870		)
	Net premiums written		860,406			1,073,800			1,934,206
	Net premiums earned		833,912			1,030,066			1,863,978
	Other underwriting loss		—			(5,786		)	(5,786		)
			833,912			1,024,280			1,858,192
	Expenses
	Net losses and loss expenses		594,561			375,601			970,162
	Acquisition expenses		65,368			254,145			319,513
	General and administrative expenses		174,575			139,012			313,587
			834,504			768,758			1,603,262
	Underwriting (loss) income		$	(592	)	$	255,522		$	254,930
	Net loss ratio		71.4		%	36.4		%	52.1		%
	Acquisition expense ratio		7.8		%	24.7		%	17.1		%
	General and administrative expense ratio		20.9		%	13.5		%	16.8		%
	Combined ratio		100.1		%	74.6		%	86		%
	Reserve for losses and loss expenses		$	2,123,772		$	1,723,087		$	3,846,859
	Goodwill		$	47,925		$	43,313		$	91,238
	9.     Segment reporting, cont'd.
	The following table provides a summary of the segment revenues and results for the year ended December 31, 2013, reserve for losses and loss expenses as of December 31, 2013 and the carrying value of goodwill as of December 31, 2013:
			Insurance			Reinsurance			Total
	Revenues
	Gross premiums written		$	1,475,429		$	1,189,815		$	2,665,244
	Ceded premiums written		(542,919		)	(73,392		)	(616,311		)
	Net premiums written		932,510			1,116,423			2,048,933
	Net premiums earned		946,474			1,070,010			2,016,484
	Other underwriting loss		—			(2,046		)	(2,046		)
			946,474			1,067,964			2,014,438
	Expenses
	Net losses and loss expenses		774,425			445,259			1,219,684
	Acquisition expenses		64,778			239,652			304,430
	General and administrative expenses		157,596			137,310			294,906
			996,799			822,221			1,819,020
	Underwriting (loss) income		$	(50,325	)	$	245,743		$	195,418
	Net loss ratio		81.8		%	41.6		%	60.5		%
	Acquisition expense ratio		6.8		%	22.4		%	15.1		%
	General and administrative expense ratio		16.7		%	12.8		%	14.6		%
	Combined ratio		105.3		%	76.8		%	90.2		%
	Reserve for losses and loss expenses		$	2,158,890		$	1,843,369		$	4,002,259
	Goodwill		$	47,925		$	43,368		$	91,293
	9.     Segment reporting, cont'd.
	The following table provides a summary of the segment revenues and results for the year ended December 31, 2012, reserve for losses and loss expenses as of December 31, 2012 and the carrying value of goodwill as of December 31, 2012:
			Insurance			Reinsurance			Total
	Revenues
	Gross premiums written		$	1,429,930		$	1,119,096		$	2,549,026
	Ceded premiums written		(487,573		)	(31,958		)	(519,531		)
	Net premiums written		942,357			1,087,138			2,029,495
	Net premiums earned		955,089			1,058,811			2,013,900
	Other underwriting (loss) income		(2,684		)	501			(2,183		)
			952,405			1,059,312			2,011,717
	Expenses
	Net losses and loss expenses		855,941			665,054			1,520,995
	Acquisition expenses		75,597			227,582			303,179
	General and administrative expenses		125,108			110,581			235,689
			1,056,646			1,003,217			2,059,863
Underwriting (loss) income		$	(104,241	)	$	56,095		$	(48,146	)
Net loss ratio		89.6		%	62.8		%	75.5		%
Acquisition expense ratio		7.9		%	21.5		%	15.1		%
General and administrative expense ratio		13.1		%	10.4		%	11.7		%
Combined ratio		110.6		%	94.7		%	102.3		%
Reserve for losses and loss expenses		$	2,287,052		$	1,953,824		$	4,240,876
Goodwill		$	47,925		$	43,014		$	90,939
The following table reconciles total segment results to income before income taxes for the years ended December 31, 2014, 2013 and 2012:
		2014			2013			2012
Total underwriting income (loss)		$	254,930		$	195,418		$	(48,146	)
Net investment income		131,543			166,216			173,326
Net foreign exchange (losses) gains		(3,839		)	(14,214		)	15,911
Net realized and unrealized gains		14,283			15,164			72,139
Net impairment losses recognized in earnings		(625		)	(1,616		)	(847		)
Amortization of intangibles		(6,484		)	(7,012		)	(10,347		)
Interest expense		(40,968		)	(36,188		)	(36,174		)
Income before income taxes		$	348,840		$	317,768		$	165,862
9.     Segment reporting, cont'd.
The following table provides gross premiums written by line of business for the years ended December 31, 2014, 2013 and 2012:
Business Segment		2014			2013			2012
Insurance
Agriculture		$	866,025		$	954,389		$	903,730
Casualty and other specialty		396,113			303,803			296,325
Professional lines		263,538			148,537			169,815
Property, marine and energy		190,452			68,700			60,060
Total Insurance		1,716,128			1,475,429			1,429,930
Reinsurance
Catastrophe		343,213			355,751			378,387
Property		287,326			297,806			349,579
Casualty		159,533			241,358			208,353
Professional lines		174,656			163,594			59,076
Specialty		213,220			131,306			123,701
Total Reinsurance		1,177,948			1,189,815			1,119,096
Total		$	2,894,076		$	2,665,244		$	2,549,026
The following table provides the geographic distribution of gross premiums written for the years ended December 31, 2014, 2013 and 2012:
		2014			2013			2012
United States		$	2,054,431		$	1,960,693		$	1,901,686
Worldwide		456,078			435,655			412,941
Europe		172,077			153,516			121,363
Australasia		61,994			25,191			22,497
Japan		45,618			33,879			36,392
Canada		19,622			15,403			17,248
Other		84,256			40,907			36,899
Total gross premiums written		$	2,894,076		$	2,665,244		$	2,549,026
The Company attributes gross premiums written to the geographic region in which the risks originate.

Goodwill_And_Intangible_Assets

Goodwill And Intangible Assets	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill And Intangible Assets	10.     Goodwill and intangible assets
	The following table shows an analysis of goodwill and intangible assets for the years ended December 31, 2014 and 2013:
		Goodwill			Intangible			Intangible			Total
					assets with			assets with
					indefinite			finite lives
					lives
	Net balance at December 31, 2012	$	90,939		$	17,229		$	63,832		$	172,000
	Additions	354			—			36			390
	Amortization	—			—			(7,012		)	(7,012		)
	Net balance at December 31, 2013	$	91,293		$	17,229		$	56,856		$	165,378
	Additions	(55		)	—			16			(39		)
	Amortization	—			—			(6,484		)	(6,484		)
	Impairment loss	—			(5,450		)	—			(5,450		)
	Net balance at December 31, 2014	$	91,238		$	11,779		$	50,388		$	153,405
	Gross balance	$	91,238		$	17,229		$	138,042		$	246,509
	Accumulated amortization	—			—			(87,654		)	(87,654		)
	Accumulated impairment losses	—			(5,450		)	—			(5,450		)
	Net balance	$	91,238		$	11,779		$	50,388		$	153,405
	For the year ended December 31, 2014, a valuation analysis was performed to determine the fair value of the Company's intangible assets with indefinite lives. This valuation analysis showed that certain of the Company's U.S. insurance licenses, which are included in the Company's Insurance business segment, were impaired by $5.5 million (2013 - nil). The determination of this impairment was a result of an evaluation of recent sales prices for companies with similar insurance licenses, which indicated that the prices for excess and surplus lines licenses are lower due to the passage of Dodd-Frank legislation which has standardized and simplified the process to obtain excess and surplus lines licenses. The impairment loss of $5.5 million is included within net realized and unrealized gains in the Consolidated Statements of Income and Comprehensive Income.
	No impairment of the Company’s goodwill asset was noted following the annual impairment review for the years ended December 31, 2014 and 2013. No changes were made in the methodologies and assumptions used in the Company’s application of its impairment testing. The Company expects the amortization of the intangible assets with finite lives to approximate $6.3 million in each of 2015, 2016 and 2017, $6.2 million in 2018 and 2019, and $19.1 million in all years thereafter.

Commitments_And_Contingencies

Commitments And Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	11.     Commitments and contingencies
	Concentrations of credit risk. The areas where significant concentrations of credit risk may exist include reinsurance recoverables, investments and cash and cash equivalents. The Company’s reinsurance recoverables on paid and unpaid losses at December 31, 2014 and 2013 amounted to $889.1 million and $758.0 million, respectively, and resulted from reinsurance arrangements entered into in the normal course of operations. A credit exposure exists with respect to reinsurance recoverables as they may become uncollectible. The Company manages its credit risk in its reinsurance relationships by transacting with reinsurers that it considers financially sound and, if necessary, the Company may hold collateral in the form of cash, trust accounts and/or irrevocable letters of credit. This collateral can be drawn on for amounts that remain unpaid beyond specified time periods on an individual reinsurer basis. As of December 31, 2014, $542.5 million of reinsurance recoverable on paid and unpaid losses (2013 – $391.7 million) was due from reinsurers rated A- or better by A.M. Best or S&P. An additional $339.6 million (2013 – $356.0 million) of reinsurance recoverable on paid and unpaid losses was due from a U.S. government sponsored reinsurance program as of December 31, 2014. At December 31, 2014 and 2013, the Company held collateral of $199.7 million and $14.2 million, respectively, related to its ceded reinsurance agreements.
	11.     Commitments and contingencies, cont'd.
	As of December 31, 2014, substantially all the Company’s cash and investments were held by three custodians.
	The Company’s investment guidelines limit the amount of credit exposure to any one issuer other than the U.S. Treasury and certain other foreign government obligations rated AAA.
	Major production sources. The following table shows the percentage of net premiums written generated through the Company’s largest brokers for the years ended December 31, 2014, 2013 and 2012:
	Broker		2014		2013		2012
	Marsh & McLennan Companies, Inc.		21.9	%	19.5	%	16.9	%
	Aon Benfield		15.1	%	17.7	%	17.4	%
	Willis Companies		13.2	%	11.9	%	15.8	%
	Total of largest brokers		50.2	%	49.1	%	50.1	%
	Letters of credit. As of December 31, 2014, the Company had issued letters of credit of $204.0 million (2013 – $260.3 million) under its Credit Facility in favor of certain ceding companies to collateralize obligations. As of December 31, 2014, the Company had issued letters of credit of $5.9 million (December 31, 2013 - nil) under its LOC Agreement. Letters of credit issued under the LOC Agreement are required to be collateralized with cash or investments.
	Investment commitments. As of December 31, 2014 and 2013, the Company had pledged cash and cash equivalents and fixed maturity investments of $130.6 million and $146.1 million, respectively, in favor of certain ceding companies to collateralize obligations. As of December 31, 2014 and 2013, the Company had also pledged $240.0 million and $302.7 million of its cash and fixed maturity investments as required to meet collateral obligations for $209.9 million and $260.3 million in secured letters of credit outstanding under its credit facilities, respectively. In addition, at December 31, 2014 and 2013, cash and fixed maturity investments with fair values of $205.2 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 December 31, 2014 and 2013. See Note 3.
	Reinsurance commitments. In the ordinary course of business, the Company enters into reinsurance agreements that may include terms which could require the Company to collateralize certain of its obligations.
	Employment agreements. The Company has entered into employment agreements with certain officers that provide for equity incentive awards, executive benefits and severance payments under certain circumstances.
	Operating leases. The Company leases office space and office equipment under operating leases. Future minimum lease commitments at December 31, 2014 are as follows:
	Year ending December 31,	Amount
	2015	15,923
	2016	12,779
	2017	11,976
	2018	10,936
	2019	11,386
	2020 and thereafter	33,783
		$	96,783
	11.     Commitments and contingencies, cont'd.
	Total lease expense under operating leases for the year ended December 31, 2014 was $14.7 million (2013 – $14.7 million; 2012 – $15.2 million). Total sublease income included in total lease expense under operating leases for the year ended December 31, 2014 was $1.3 million (2013 - $0.8 million; 2012 - $0.3 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, results of operations or business. Pursuant to the Company’s insurance and reinsurance agreements, disputes are generally required to be finally settled by arbitration.

Shareholders_Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
Shareholders' Equity	12.     Shareholders' equity
	The Company’s share capital at December 31, 2014 and 2013 is comprised as follows:
			2014			2013
	Preferred shares
	Authorized – $1.00 par value each		17,200,000			17,200,000
	Issued, outstanding and fully paid:
	Series A preferred shares – $1.00 par value each; aggregate liquidation preference $200,000 (2013 - $200,000)		8,000,000			8,000,000
	Series B preferred shares – $1.00 par value each; aggregate liquidation preference $230,000 (2013 - $230,000)		9,200,000			9,200,000
			17,200,000			17,200,000
	Common shares
	Authorized - $1.00 par value each		120,000,000			120,000,000
	Issued, outstanding and fully paid:
	Ordinary common shares - $1.00 par value each		44,765,153			44,368,742
	During 2014, the Company issued restricted shares under its equity compensation plans (Note 15). The common shares issued, outstanding and fully paid for at December 31, 2014 includes 1,290,894 restricted shares.
	On October 10, 2005, Endurance Holdings issued 8,000,000 shares of its 7.75% Non-Cumulative Preferred Shares, Series A (the “Series A Preferred Shares”) and on June 1, 2011, Endurance Holdings issued 9,200,000 shares of its 7.5% Non-Cumulative Preferred Shares, Series B (the “Series B Preferred Shares”). The Series A Preferred Shares and Series B Preferred Shares sold were registered under the Securities Act of 1933, as amended, and are traded on the New York Stock Exchange. The Series A Preferred Shares and Series B Preferred Shares were both issued at a price to the public of $25.00 per share. Endurance Holdings received net proceeds of $193.5 million from its offering of Series A Preferred Shares and $224.0 million from its offering of Series B Preferred Shares, in each case after expenses and underwriting discounts. The proceeds from both offerings were used to provide additional capital to Endurance Holdings’ subsidiaries and for other general corporate purposes.
	The Series A Preferred Shares and Series B Preferred Shares have no stated maturity date and are redeemable in whole or in part at the option of Endurance Holdings any time after December 15, 2015 (in the case of the Series A Preferred Shares) and after June 1, 2016 (in the case of the Series B Preferred Shares) in each case at a redemption price of $25.00 per share plus any declared and unpaid dividends, without accumulation of any undeclared dividends. Endurance Holdings may redeem all but not less than all of the Series A Preferred Shares or Series B Preferred Shares before their respective redemption dates at a redemption price of $26.00 per share, plus any declared and unpaid dividends to the date of redemption, if Endurance Holdings is required to submit a proposal to the holders of the Series A Preferred Shares or Series B Preferred Shares concerning an amalgamation, consolidation, merger, similar corporate transaction or change in Bermuda law.
	12.     Shareholders' equity, cont'd.
	Dividends on the Series A Preferred Shares and Series B Preferred Shares, when, as and if declared by the Board of Directors of Endurance Holdings or a duly authorized committee of the board, accrue and are payable on the liquidation preference amount from the original issue date, quarterly in arrears on each dividend payment date, at an annual rate of 7.75% in the case of the Series A Preferred Shares and an annual rate of 7.5% in the case of the Series B Preferred Shares. Dividends on the Series A Preferred Shares and Series B Preferred Shares are not cumulative.
	Upon any voluntary or involuntary liquidation, dissolution or winding-up of Endurance Holdings, holders of the Series A Preferred Shares, Series B Preferred Shares and any parity shares are entitled to receive out of Endurance Holdings’ assets available for distribution to shareholders, before any distribution is made to holders of Endurance Holdings’ common equity securities, a liquidating distribution in the amount of $25.00 per Series A Preferred Share and Series B Preferred Share, plus any declared and unpaid dividends, without accumulation of any undeclared dividends. Distributions will be made pro rata as to the Series A Preferred Shares, Series B Preferred Shares and any parity shares and only to the extent of Endurance Holdings’ assets, if any, that are available after satisfaction of all liabilities to creditors.
	In conjunction with the issuance by the Company of the Series A Preferred Shares, the Company entered into a “Declaration of Covenant” for the benefit of the holders of the 7% Senior Notes. The Covenant states that the Company will redeem its Series A Preferred Shares only if the total redemption price is less than or equal to the proceeds Endurance Holdings or its subsidiaries have received during the six months prior to the date of such redemption from the sale of certain qualifying securities that, among other things, are, with limited exceptions, pari passu with or junior to the Series A Preferred Shares upon the Company’s liquidation, dissolution or winding-up; perpetual, or have a mandatory redemption or maturity date that is not less than sixty years after the initial issuance of such securities; and provide for dividends or other income distributions that are non-cumulative.
	Holders of the Series A Preferred Shares and the Series B Preferred Shares have no voting rights, except with respect to certain fundamental changes in the terms of the Series A Preferred Shares or the Series B Preferred Shares and in the case of certain dividend non-payments or as otherwise required by Bermuda law or Endurance Holdings’ bye-laws.
	On February 27, 2014, the Company’s Board of Directors authorized the repurchase of up to 5.0 million ordinary shares and share equivalents through February 28, 2016. This authorization superseded previous authorizations. No common shares were repurchased by the Company during 2014. During 2013, under programs authorized by the Company’s Board of Directors, the Company repurchased 318,252 of its ordinary shares in open market and privately negotiated transactions at an average price of $45.83 per share. Common shares repurchased by the Company are not cancelled and are classified as treasury shares. The Company’s treasury shares are recorded at cost as a reduction in common shares and additional paid-in capital within shareholders’ equity. There were 5.0 million shares authorized for repurchase remaining at December 31, 2014 (2013 – nil).
	12.     Shareholders' equity, cont'd.
	Accumulated other comprehensive income
	The following table presents the changes in accumulated other comprehensive income balances by component for the years ended December 31, 2014 and 2013:
			For the Year Ended December 31, 2014
			Losses on				Unrealized gains			Foreign currency translation			Total
			cash flow hedges				(losses) on available for sale			adjustments
							securities
	Beginning balance		$	(1,855	)		$	45,950		$	18,636		$	62,731
	Other comprehensive income (loss) before reclassifications		—				60,632			(26,264		)	34,368
	Amounts reclassified from accumulated other		89				(20,482		)	—			(20,393		)
	comprehensive income (1)
	Net current period other comprehensive income (loss)		89				40,150			(26,264		)	13,975
	Ending balance		$	(1,766	)		$	86,100		$	(7,628	)	$	76,706
	-1	All amounts are net of tax.
			For the Year Ended December 31, 2013
			Losses on				Unrealized gains			Foreign currency translation			Total
			cash flow hedges				(losses) on available for sale			adjustments
							securities
	Beginning balance		$	(1,944	)		$	141,731		$	12,676		$	152,463
	Other comprehensive income (loss) before reclassifications		—				(83,951		)	5,960			(77,991		)
	Amounts reclassified from accumulated other		89				(11,830		)	—			(11,741		)
	comprehensive income(1)
	Net current period other comprehensive income (loss)		89				(95,781		)	5,960			(89,732		)
	Ending balance		$	(1,855	)		$	45,950		$	18,636		$	62,731
	-1	All amounts are net of tax.
	12.     Shareholders' equity, cont'd.
	The following tables present the significant items reclassified out of accumulated other comprehensive income during the years ended December 31, 2014 and 2013:
	For the Year Ended December 31, 2014
	Details about accumulated other		Amount reclassified				Affected line item in the Consolidated Statements
	comprehensive income components		from accumulated				of Income and Comprehensive Income
			other comprehensive
			income
	Losses on cash flow hedges - Debt		$	89			Interest expense
			89				Total before income taxes
			—				Income tax expense
			$	89			Total net of income taxes
	Unrealized (gains) losses on available for sale securities		$	(19,406	)		Net realized and unrealized gains
			625				Net impairment losses recognized in earnings
			(18,781		)		Total before income taxes
			(1,701		)		Income tax benefit
			$	(20,482	)		Total net of income taxes
	For the Year Ended December 31, 2013
Details about accumulated other		Amount reclassified				Affected line item in the Consolidated Statements
comprehensive income components		from accumulated				of Income and Comprehensive Income
		other comprehensive
		income
Losses on cash flow hedges - Debt		$	89			Interest expense
		89				Total before income taxes
		—				Income tax expense
		$	89			Total net of income taxes
Unrealized (gains) losses on available for sale securities		$	(14,497	)		Net realized and unrealized gains
		1,616				Net impairment losses recognized in earnings
		(12,881		)		Total before income taxes
		1,051				Income tax expense
		$	(11,830	)		Total net of income taxes

Earnings_Per_Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings Per Share	13.     Earnings per share
	The following table sets forth the computation of basic and diluted earnings per share for the years ended December 31, 2014, 2013 and 2012:
			2014			2013			2012
	Numerator:
	Net income available to common and participating common shareholders		$	315,700		$	279,165		$	129,766
	Less amount allocated to participating common shareholders (1)		(9,118		)	(6,444		)	(2,113		)
	Net income allocated to common shareholders		$	306,582		$	272,721		$	127,653
	Denominator:
	Weighted average shares - basic		43,368,062			42,817,624			42,567,736
	Share equivalents:
	Options		47,111			—			31,833
	Restricted share units		70			583			2,266
	Weighted average shares - diluted		43,415,243			42,818,207			42,601,835
	Basic earnings per common share		$	7.07		$	6.37		$	3
	Diluted earnings per common share		$	7.06		$	6.37		$	3
	-1	Represents earnings and dividends attributable to holders of unvested restricted shares issued under the Company’s stock compensation plans that are considered participating. In periods of loss, no losses are allocated to participating common shareholders (unvested restricted shares).
	The following table sets forth dividends declared in the years ended December 31, 2014, 2013 and 2012, respectively:
			2014			2013			2012
	Dividends declared per Series A preferred share		$	1.9375		$	1.9375		$	1.9375
	Dividends declared per Series B preferred share		$	1.875		$	1.875		$	1.875
	Dividends declared per common share		$	1.36		$	1.28		$	1.24

Related_Party_Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Related Party Transactions	14.     Related party transactions
	Pyramis Global Advisors, a subsidiary of FMR, LLC (“Fidelity”), provides investment management services to the Company. Fidelity and its affiliates owned 3.6 million or 8.1% of Endurance Holdings’ ordinary shares outstanding at December 31, 2014 and were therefore considered a related party. The Company incurred investment management fees totaling $1.4 million (2013 - $1.4 million; 2012 - $1.4 million) to this investment manager of which $0.3 million was accrued at December 31, 2014 (2013 - $0.4 million).

StockBased_Employee_Compensati

Stock-Based Employee Compensation And Other Stock Plans	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Employee Compensation And Other Stock Plans	15.     Stock-based employee compensation and other stock plans
	At its meeting on February 28, 2007, the Company’s Board of Directors adopted the 2007 Equity Incentive Plan (“2007 Plan”) to allow for the issuance of equity incentives to non-employee directors of the Company and eligible employees of the Company and its subsidiaries. The 2007 Plan was approved by the Company’s shareholders at the Annual General Meeting of Shareholders held on May 9, 2007. At that time, the Company’s existing Amended and Restated 2002 Stock Option Plan and the Amended and Restated 2003 Non-Employee Director Incentive Plan were merged into the new 2007 Plan.
	The 2007 Plan allows the Company to grant to employees and non-employee directors restricted shares, restricted share units, stock appreciation rights, share bonuses, options to purchase the Company’s ordinary shares and other forms of equity incentive awards, as determined by the Compensation Committee of the Company’s Board of Directors.
	Under the terms of the 2007 Plan as amended, and after the consolidation of the Company’s previous plans, a total of 2,100,000 ordinary shares were reserved for issuance. At a meeting on February 11, 2010, the Company’s Board of Directors adopted a resolution to add 1,795,000 ordinary shares to the 2007 Plan, which was subsequently approved by the Company’s shareholders at the Annual General Meeting of Shareholders held on May 13, 2010. After the approval of the additional shares, a total of 3,895,000 ordinary shares were reserved for issuance. The Company issues new ordinary shares upon the issuance of share based equity incentives, such as restricted shares, or the exercise or settlement of outstanding derivative equity incentives, such as options or restricted share units. As of December 31, 2014, 1,738,370 (2013 - 2,107,889) ordinary shares remained available for issuance under the 2007 and prior Plans.
	On May 28, 2013, the Board of Directors elected John R. Charman as the Company’s Chairman and Chief Executive Officer. Mr. Charman received an option to purchase 800,000 ordinary shares at an exercise price of $48.20 per share, and a grant of 708,890 restricted shares, as an employment inducement pursuant to Rule 303A.08 of the New York Stock Exchange Corporate Governance Standards and were made outside of the 2007 Plan.
	Options
	The 800,000 options awarded to Mr. Charman will vest annually, in five equal tranches commencing on May 28, 2013, subject to Mr. Charman’s continued employment, or in the event of certain terminations of employment and other events. Mr. Charman's options have a 10-year contractual life.
	Prior to 2005, the Company issued stock options to employees and non-employee directors, with exercise prices equal to the fair market values of the Company’s ordinary shares on the grant dates. Options generally vested at a rate of 20% per year over a five-year term. Option awards have a 10-year contractual life.
	A summary of option activity, including options held by employees and non-employee directors, during the year ended December 31, 2014 is presented below:
		For the year ended December 31, 2014
	Options Outstanding	Number of		Weighted		Weighted	Aggregate
		Options		Average		Average	Intrinsic Value
				Exercise Price		Remaining
						Contractual Life
						(years)
	Beginning of year	815,000		$	47.94
	Granted	—		—
	Exercised	(15,000	)	33.91
	Forfeited	—		—
	Outstanding, end of year	800,000		$	48.2	8.41	$	9,312
	Exercisable and vested options, end of year	320,000		$	48.2	8.41	$	3,725
	15.     Stock-based employee compensation and other stock plans, cont'd.
	No options were granted during the year ended December 31, 2014. During the year ended December 31, 2013, 800,000 options were granted with a weighted average grant date fair value of $10.2 million. No options were granted during the year ended December 31, 2012. The Company uses the Black-Scholes-Merton formula to estimate the value of stock options granted. No options expired during the years ended December 31, 2014, 2013 and 2012. During the years ended December 31, 2014 and 2013, 160,000 and 160,000 options vested, respectively. No options vested during the year ended December 31, 2012. The total intrinsic value of options exercised during the years ended December 31, 2014, 2013 and 2012 was $0.3 million, $0.5 million, and $1.4 million, respectively. The Company received proceeds of $0.5 million from the exercise of options during the year ended December 31, 2014. The Company issued new ordinary shares in connection with the exercise of the above options.
	For the years ended December 31, 2014 and 2013, compensation costs recognized in earnings for all options totaled $3.1 million and $4.5 million, respectively (2012 - nil).
	There were unrecognized stock-based compensation expenses of $2.6 million related to unvested stock options at December 31, 2014. This expense is expected to be recognized between 2015 and 2017, with approximately 61.6% expected to be recognized during 2015.
	Restricted Shares and Restricted Share Units
	The Company has issued restricted shares and restricted share units to employees and non-employee directors. The fair value of the restricted shares and restricted share units granted was equal to the fair market value of the Company’s ordinary shares on the grant date. Compensation equal to the fair market value of the restricted shares and restricted share units at the measurement date is amortized and charged to income over the vesting period. Restricted shares granted to employees generally vest pro rata over a four-year period. Restricted shares are forfeited upon departure from the Company for any reason prior to the applicable vesting date other than in cases where an employee meets certain retirement eligibility criteria which allow for continuing post-employment vesting of restricted shares, subject to compliance with certain non-competition obligations.
	The 708,890 restricted shares awarded to Mr. Charman, as discussed above, will vest annually, in five equal tranches commencing on May 28, 2013, subject to Mr. Charman’s continued employment, or in the event of certain terminations of employment and other events.
	Restricted shares granted to non-employee directors vest twelve months following the date of grant and are forfeited upon departure from the Board of Directors for any reason prior to the applicable vesting date.
	The Company has granted restricted share units in an amount equal to the dividends that would have been paid on the notional amount of certain options held by employees of the Company. These restricted share units vest and settle on the first March 1st following the six-month anniversary of the date of issuance of the unit.
	The Company generally withholds an amount sufficient to satisfy any federal, state or local withholding tax requirements associated with the vesting of the restricted shares and the restricted share units held by employees.
	15.     Stock-based employee compensation and other stock plans, cont'd.
	A summary of the restricted share and restricted share unit activity during the year ended December 31, 2014, is presented below:
		Number of		Aggregate
		Shares/Units		Intrinsic Value
	Unvested, beginning of year	1,261,260
	Granted	505,997
	Settled	(402,479	)
	Forfeited	(73,884	)
	Unvested, end of year	1,290,894
	Outstanding, end of year	1,290,894		$	77,247
	During the years ended December 31, 2014, 2013 and 2012, the Company granted an aggregate of 505,997, 503,097 and 437,284 restricted shares and restricted share units under the 2007 Plan. As mentioned above, the Company also granted 708,890 restricted shares to Mr. Charman outside of the 2007 Plan on May 28, 2013. The restricted shares and restricted share units granted had weighted average grant date fair values of $26.7 million, $58.1 million and $16.8 million in the years ended December 31, 2014, 2013 and 2012, respectively. During the years ended December 31, 2014, 2013 and 2012, the aggregate fair value of restricted shares and restricted share units that vested was $18.7 million, $17.1 million and $11.7 million, respectively.
	For the years ended December 31, 2014, 2013 and 2012, compensation costs recognized in earnings for all restricted shares and restricted share units were $27.9 million, $23.5 million, and $11.2 million, respectively. At December 31, 2014, compensation costs not yet recognized related to non-vested awards was $23.3 million (2013 – $29.7 million). This expense is expected to be recognized between 2015 and 2018, with approximately 62.4% expected to be recognized during 2015.
	Employee Share Purchase Plan
	On October 26, 2005, Endurance Holdings’ shareholders approved the Employee Share Purchase Plan (the “ESPP”). The ESPP is not subject to any provisions of the Employee Retirement Income Security Act of 1974 as amended, and is not a qualified plan within the meaning of Section 402(a) of the Internal Revenue Code of 1986, as amended (the “Code”). The ESPP is a qualified plan under Section 423 of the Code.
	Following approval by the Company’s shareholders in 2005, 200,000 of Endurance Holdings’ ordinary shares were reserved for issuance under the ESPP. At a meeting on February 23, 2011, the Company’s Board of Directors adopted a resolution to add 200,000 ordinary shares to the ESPP. The addition of 200,000 ordinary shares to the ESPP was approved by the Company’s shareholders at the Annual General Meeting of Shareholders held on May 11, 2011. After approval of the additional ordinary shares, a total of 400,000 ordinary shares were reserved for issuance under the ESPP.
	Under the terms of the ESPP, employees of Endurance Holdings and certain of its subsidiaries may purchase Endurance Holdings’ ordinary shares at a 15% discount to the closing market price on the purchase date. Participants are eligible to receive dividends on the shares purchased in the ESPP and are entitled to vote such shares at any Annual General or Special Meeting of Shareholders. These shares are restricted from sale, transfer or certification for one year from the purchase date.
	Total expenses related to this plan for the year ended December 31, 2014 was approximately $234,000 (2013 – $167,000; 2012 – $165,000).

Pension_Plan

Pension Plan	12 Months Ended
	Dec. 31, 2014
Pension and Other Postretirement Benefit Expense [Abstract]
Pension Plan	16.     Pension plan
	The Company provides pension benefits to eligible employees through various defined contribution plans sponsored by the Company. Under the Company’s defined contribution plans, the Company makes contributions to its employees’ accounts in amounts ranging from 4% to 12% of its employees’ eligible earnings. In addition, under certain defined contribution plans, employee contributions may be supplemented by matching contributions made by the Company based on the level of employee contribution. Lastly, the Company may provide additional contributions, depending on its annual financial performance. The employee and Company contributions in the defined contribution plans are invested at the election of each employee in one or more of several investment portfolios offered by third party investment advisors. Company contributions for the year ended December 31, 2014 resulted in an expense of $12.6 million being recorded in earnings (2013 – $10.8 million; 2012 – $7.4 million).

Statutory_Requirements_And_Div

Statutory Requirements And Dividend Restrictions	12 Months Ended
	Dec. 31, 2014
Statutory Requirements And Dividend Restrictions [Abstract]
Statutory Requirements And Dividend Restrictions	17.     Statutory requirements and dividend restrictions
	Our insurance and reinsurance operations are subject to insurance and/or reinsurance laws and regulations in the jurisdictions in which they operate, the most significant of which are Bermuda, the United States and the United Kingdom. These regulations include certain restrictions on the amount of dividends or other distributions, such as loans or cash advances, available to shareholders without prior approval of the insurance regulatory authorities.
	The combined statutory capital and combined statutory net income (loss) for our principal operating subsidiaries in their respective jurisdictions were as follows:
	Statutory capital		Bermuda(1)					United States					Other(2)
			2014		2013			2014			2013		2014		2013
	Required statutory capital		$	955,903	$	965,348		$	244,587		$	236,652	$	77,366	$	63,369
	Actual statutory capital		2,876,927		2,618,198			702,513			654,480		603,288		512,579
	Statutory net income (loss)		Bermuda		United States			Other(2)
	Year ended December 31, 2014		$	453,127	$	28,450		$	14,103
	Year ended December 31, 2013		454,840		(48,035		)	(36,678		)
	Year ended December 31, 2012		355,118		(147,325		)	2,829
	-1	Bermuda statutory capital includes an investment in affiliate asset, which represents its interest in the remaining insurance and reinsurance operations of the Company included in the United States and Other columns above.
	-2	Includes Endurance U.K. and Endurance Bermuda’s Singapore branch.
	Bermuda
	As a Bermuda holding company, Endurance Holdings is subject to the Companies Act 1981, which limits the Company’s ability to pay dividends and make distributions to its shareholders. The Company’s retained earnings are unrestricted; however, the Company is not permitted to declare or pay a dividend, or make a distribution out of contributed surplus, if it is, or would after the payment be, unable to pay its liabilities as they come due, or if the realizable value of its assets would be less than its liabilities. Endurance Holdings had, as of December 31, 2014, $2.4 billion in retained earnings, $0.1 billion in accumulated other comprehensive income and an additional $0.6 billion in contributed surplus available to declare or pay a dividend, or make a distribution out of contributed surplus, so long as Endurance Holdings remained in compliance with the Companies Act 1981 following such dividend or distribution. Endurance Holdings relies on dividends from Endurance Bermuda to provide cash flow required for debt service and dividends to shareholders.
	Endurance Bermuda is a registered Class 4 insurer under the Insurance Act 1978 and related regulations. Endurance Bermuda is required to maintain minimum solvency standards and to hold available statutory capital and surplus equal to or exceeding the Enhanced Capital Requirement as determined by the Bermuda Monetary Authority based upon a standard mathematical model that correlates the risk underwritten to the capital that is dedicated to the business. The required capital noted in the table above has been based on the Enhanced Capital Requirement. In addition to the Enhanced Capital Requirement, Endurance Bermuda is required to maintain a minimum statutory liquidity ratio and solvency margin. For all periods presented herein, Endurance Bermuda materially exceeded these minimum requirements.
	17.     Statutory requirements and dividend restrictions, cont'd.
	Endurance Bermuda’s ability to pay dividends and make capital distributions is subject to certain regulatory restrictions based on the Enhanced Capital Requirement, limits on the amount of Endurance Bermuda’s premiums written and net reserves for losses and loss expenses and a minimum general capital and surplus requirement of $100.0 million. At December 31, 2014, Endurance Bermuda can pay dividends of $719.2 million (2013 - $654.5 million) to Endurance Holdings without prior approval under Bermuda law.
	United States
	Endurance U.S. Reinsurance, Endurance American, Endurance American Specialty and Endurance Risk Solutions are subject to regulation by the Delaware Department of Insurance. American Agri-Business is subject to regulation by the Texas Department of Insurance. Endurance’s Delaware and Texas domiciled entities must maintain a minimum level of statutory capital as established by such jurisdictions. The amount of required capital is determined through the use of the Risk Based Capital model established by the National Association of Insurance Commissioners and adopted by Delaware and Texas. The required capital noted in the table above has been based on the Risk Based Capital model and represents the authorized control level risk based capital for these entities.
	Dividends for each U.S. operating subsidiary are limited to the greater of 10% of policyholders’ surplus or statutory net income, excluding realized capital gains for Endurance’s Delaware domiciled entities. In addition, dividends may only be declared or distributed out of earned surplus. At December 31, 2014, Endurance U.S. Reinsurance, Endurance American, Endurance Risk Solutions and Endurance American Specialty did not have earned surplus and thus were precluded from declaring or distributing dividends during 2015 without the prior approval of the applicable insurance regulator. If the parent company is also an insurer, as is the case with Endurance American, Endurance American Specialty and Endurance Risk Solutions, the parent company or companies must also meet their own dividend eligibility requirements in order to pass along any dividends received from subsidiary insurance companies. At December 31, 2014, American Agri-Business (with notice to the Texas Department of Insurance) could pay dividends of $3.7 million (2013 - $3.9 million) without prior regulatory approval.
	Other Jurisdictions
	The required and actual statutory capital amounts in the “Other” category in the table above include amounts related to Endurance U.K. and Endurance Bermuda’s Singapore branch (“Singapore Branch”). Under the jurisdiction of the United Kingdom’s Prudential Regulation Authority (“PRA”), Endurance U.K. must maintain a margin of solvency at all times, which is determined based on the type and amount of insurance business written. Insurers are required to calculate their required minimum solvency margin and to report it to the PRA. The PRA also mandates calculation of an Enhanced Capital Requirement for Endurance U.K. At December 31, 2014 and 2013, the actual capital for Endurance U.K. exceeded the capital requirements currently promulgated by the PRA.
	The Singapore Branch is subject to Fund Solvency and Capital Adequacy requirements by the Monetary Authority of Singapore as a foreign company in Singapore and is regulated by the Monetary Authority of Singapore pursuant to the Insurance Act in Singapore. At December 31, 2014 and 2013, the Singapore Branch complied with the capital requirements promulgated by the Monetary Authority of Singapore.
	The PRA regulatory requirements impose no explicit restrictions on Endurance U.K.’s ability to pay a dividend, but Endurance U.K. would have to notify the PRA 28 days prior to any proposed dividend payment. Dividends may only be distributed from profits available for distribution. At December 31, 2014 Endurance U.K did not have retained profits available for distribution.

Taxes

Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Taxes	18.     Taxes
	The Company has operating subsidiaries and branch operations in the United States, United Kingdom, Switzerland and Singapore, which are subject to the relevant taxes in those jurisdictions. During 2014, the Internal Revenue Service completed its audit of the income tax returns of the Company’s U.S. subsidiaries for 2009, 2010 and 2011. The audit results were immaterial to the operations of the Company. As of December 31, 2014, none of the Company’s operating subsidiaries or branch operations were under examination in any of the jurisdictions in which they operate. The Company remains subject to examination for tax years 2010 through 2014.
	Endurance Holdings and Endurance Bermuda are not required to pay any income or capital gains taxes in Bermuda. Endurance Bermuda has received written assurance dated May 16, 2011 and Endurance Holdings has received written assurance dated May 17, 2011 from the Minister of Finance of Bermuda under the Exempted Undertakings Tax Protection Act of 1966 of Bermuda, as amended, that in the event any legislation is enacted in Bermuda imposing any tax computed on profits or income, or computed on any capital asset, gain or appreciation or any tax in the nature of estate duty or inheritance tax, such tax shall not be applicable to the Company until March 31, 2035 provided that the assurance is subject to the condition that it will not prevent the application of any taxes payable by the Company in respect of real property or leasehold interests in Bermuda held by it. Endurance Holdings and Endurance Bermuda intend to operate in a manner such that they will owe no United States tax other than premium excise tax and withholding taxes on certain investments.
	The income tax expense was as follows for the years ended December 31, 2014, 2013 and 2012, respectively:
			2014			2013			2012
	Current income tax expense		$	(1,804	)	$	(3,089	)	$	(5,029	)
	Deferred income tax benefit (expense)		1,414			(2,764		)	1,683
	Income tax expense		$	(390	)	$	(5,853	)	$	(3,346	)
	Of the 2014 current income tax expense, $1.8 million related to taxes incurred in the United States (2013 – $3.1 million; 2012 – $4.6 million). Of the deferred income tax benefit (expense), $1.4 million related to deferred income tax benefit in the United States (2013 – $(2.8) million; 2012 – $1.6 million). A full valuation allowance has been recorded against the net asset position of Endurance Bermuda’s foreign branches and Endurance U.K.
	The actual income tax expense attributable to income for the years ended December 31, 2014, 2013 and 2012 differed from the amount computed by applying the combined effective rate of 0% under Bermuda law to income before income taxes, as a result of the following:
			2014			2013			2012
	Computed expected tax expense		$	—		$	—		$	—
	Tax (expense) benefit effect on foreign taxes		(1,661		)	31,054			51,059
	Change in valuation allowance		1,271			(36,907		)	(54,405		)
			$	(390	)	$	(5,853	)	$	(3,346	)
	18.     Taxes, cont'd.
	Deferred income taxes represent the tax effect of the differences between the book and tax bases of assets and liabilities. Net deferred income tax assets and liabilities consisted of the following as of December 31, 2014 and 2013:
			2014			2013
	Deferred income tax assets:
	Unearned premiums		$	23,124		$	22,701
	Loss reserves		29,410			32,109
	Net operating loss carryforward		93,163			106,112
	Deferred compensation		19,588			14,943
	Deferred interest		44,951			43,341
	Realized investment losses		125			150
	Other		10,404			3,388
	Total deferred income tax assets		220,765			222,744
	Deferred income tax liabilities:
	Deferred acquisition costs		(10,843		)	(16,874		)
	Unrealized investment (gains) losses		(5,293		)	30
	Unrealized foreign exchange (gains) losses		(2,704		)	600
	Temporary differences related to acquisition		(20,344		)	(22,612		)
	Start up costs		(1,144		)	(720		)
	Other		(10,033		)	(8,785		)
	Total deferred income tax liabilities		(50,361		)	(48,361		)
	Valuation allowance		(121,409		)	(122,680		)
	Net deferred income tax asset		$	48,995		$	51,703
	Net income tax payments for the year ended December 31, 2014 totaled $0.9 million. The Company received net income tax refunds and paid net income taxes totaling $8.4 million and $1.6 million for the years ended December 31, 2013 and 2012, respectively. Net operating loss carryforwards gross of tax in the amount of $192.0 million, $57.3 million, $46.0 million and $45.8 million are available for application against future taxable income in the United States, United Kingdom, Singapore and Switzerland, respectively. These net operating loss carry forwards have no expiration date in the United Kingdom and Singapore. In Switzerland and the United States, the net operating loss carry forwards expire through 2021 and 2033, respectively.
	A valuation allowance is provided when it is more likely than not that some portion of the deferred tax assets will not be realized. At December 31, 2014, management has established a valuation allowance of $121.4 million (2013 – $122.7 million) against net deferred tax assets in the Company’s United States subsidiaries, United Kingdom subsidiary and non-U.S. branches.
	The Company’s income before income taxes was distributed as follows for the years ended December 31, 2014, 2013 and 2012, respectively:
			2014			2013			2012
	U.S. (domestic)		$	60,112		$	13,103		$	(186,882	)
	Non-U.S. (foreign) (1)		288,728			304,665			352,744
	Income before income taxes		$	348,840		$	317,768		$	165,862
	-1	The Company’s non-U.S. (foreign) operating subsidiaries write business that is exposed to risks originating in the United States.
	As of December 31, 2014 and 2013, the Company had no uncertain tax positions.

Condensed_Unaudited_Quarterly_

Condensed Unaudited Quarterly Financial Data	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Condensed Unaudited Quarterly Financial Data	19.     Condensed unaudited quarterly financial data
	The following is a summary of the unaudited quarterly data for the year ended December 31, 2014:
		Quarter Ended			Quarter Ended			Quarter Ended			Quarter Ended
		March 31, 2014			June 30, 2014			September 30, 2014			December 31, 2014
	Net premiums earned	$	396,266		$	481,538		$	514,895		$	471,279
	Net investment income	40,990			39,302			25,357			25,894
	Net realized and unrealized gains (losses)	4,872			3,411			9,788			(3,788		)
	Net impairment losses recognized in earnings	(111		)	(198		)	(102		)	(214		)
	Subtotal	$	442,017		$	524,053		$	549,938		$	493,171
	Net losses and loss expenses	$	176,896		$	259,196		$	290,269		$	243,801
	Acquisition and general and administrative expenses	$	145,363		$	165,056		$	174,307		$	148,374
	Net foreign exchange losses (gains)	$	2,964		$	319		$	783		$	(227	)
	Net income	$	104,480		$	83,163		$	76,234		$	84,573
	Preferred dividends	(8,188		)	(8,188		)	(8,188		)	(8,186		)
	Net income available to common and participating common shareholders	$	96,292		$	74,975		$	68,046		$	76,387
	Basic earnings per share	$	2.16		$	1.68		$	1.52		$	1.71
	Diluted earnings per share	$	2.16		$	1.68		$	1.52		$	1.7
	The following is a summary of the unaudited quarterly data for the year ended December 31, 2013:
		Quarter Ended			Quarter Ended			Quarter Ended			Quarter Ended
		March 31, 2013			June 30, 2013			September 30, 2013			December 31, 2013
	Net premiums earned	$	420,117		$	543,335		$	553,545		$	499,487
	Net investment income	49,305			32,468			38,097			46,346
	Net realized and unrealized gains (losses)	6,235			10,372			(6,640		)	5,197
	Net impairment losses recognized in earnings	(806		)	(579		)	(190		)	(41		)
	Subtotal	$	474,851		$	585,596		$	584,812		$	550,989
	Net losses and loss expenses	$	218,970		$	359,058		$	339,036		$	302,620
	Acquisition and general and administrative expenses	$	138,114		$	153,227		$	146,245		$	161,750
	Net foreign exchange losses	$	2,927		$	3,368		$	2,201		$	5,718
	Net income	$	100,299		$	61,019		$	83,416		$	67,181
	Preferred dividends	(8,188		)	(8,188		)	(8,188		)	(8,186		)
	Net income available to common and participating common shareholders	$	92,111		$	52,831		$	75,228		$	58,995
	Basic earnings per share	$	2.13		$	1.21		$	1.7		$	1.33
	Diluted earnings per share	$	2.13		$	1.21		$	1.7		$	1.33

Schedule_I_Summary_Of_Investme

Schedule I Summary Of Investments Other Than Investments In Related Parties	12 Months Ended
	Dec. 31, 2014
Summary of Investments, Other than Investments in Related Parties [Abstract]
Schedule I Summary Of Investments Other Than Investments In Related Parties	SCHEDULE I
	ENDURANCE SPECIALTY HOLDINGS LTD. AND SUBSIDIARIES
	SUMMARY OF INVESTMENTS OTHER THAN INVESTMENTS IN RELATED PARTIES
	AT DECEMBER 31, 2014
	(In thousands of United States dollars)
			Cost(1)		Market Value		Amount at
							Which Shown on
							the Balance Sheet
	Type of Investment:
	Fixed Maturity Investments
	U.S. government and government agencies and authorities		$	582,970	$	587,411	$	587,411
	States, municipalities and political subdivisions		39,340		39,413		39,413
	Foreign governments		239,217		240,536		240,536
	Corporate bonds		1,401,806		1,409,564		1,409,564
	Mortgage-backed securities
	Agency mortgage-backed securities		1,107,086		1,133,123		1,133,123
	Non-agency mortgage-backed securities		1,003,048		1,021,302		1,021,302
	Collateralized loan and debt obligations		247,510		248,011		248,011
	Asset-backed securities		411,529		413,221		413,221
	Total fixed maturity investments		$	5,032,506	$	5,092,581	$	5,092,581
	Short-term investments		9,015		9,014		9,014
	Equity securities		303,922		331,368		331,368
	Other investments		387,186		541,454		541,454
	Total Investments		$	5,732,629	$	5,974,417	$	5,974,417
	-1	Investments in fixed maturity investments and short-term investments are shown at amortized cost.

Schedule_II_Condensed_Financia

Schedule II Condensed Financial Statement Information Of The Registrant	12 Months Ended
	Dec. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Schedule II Condensed Financial Statement Information of the Registrant	SCHEDULE II
	ENDURANCE SPECIALTY HOLDINGS LTD.
	CONDENSED FINANCIAL STATEMENT INFORMATION OF THE REGISTRANT
	BALANCE SHEETS-PARENT ONLY
	DECEMBER 31, 2014 AND 2013
	(In thousands of United States dollars except share amounts)
		2014			2013
	ASSETS
	Investment in subsidiary	$	3,518,589		$	3,211,570
	Cash and cash equivalents	240			6,517
	Amounts due from subsidiaries	201,600			200,530
	Other assets	13,927			15,496
	Total assets	$	3,734,356		$	3,434,113
	LIABILITIES
	Debt	527,616			527,398
	Other liabilities	21,558			20,166
	Total liabilities	549,174			547,564
	SHAREHOLDERS’ EQUITY
	Preferred shares
	Series A and Series B, non-cumulative - 17,200,000 issued and outstanding (2013 - 17,200,000)	17,200			17,200
	Common shares
	Ordinary - 44,765,153 issued and outstanding (2013 - 44,368,742)	44,765			44,369
	Additional paid-in capital	598,226			569,116
	Accumulated other comprehensive income	76,706			62,731
	Retained earnings	2,448,285			2,193,133
	Total shareholders’ equity	3,185,182			2,886,549
	Total liabilities and shareholders’ equity	$	3,734,356		$	3,434,113
	See accompanying notes to the consolidated financial statements.
	SCHEDULE II
	ENDURANCE SPECIALTY HOLDINGS LTD.
	CONDENSED FINANCIAL STATEMENT INFORMATION OF THE REGISTRANT, Cont’d.
	STATEMENTS OF INCOME-PARENT ONLY
	YEARS ENDED DECEMBER 31, 2014, 2013, AND 2012
	(In thousands of United States dollars)
		2014			2013			2012
	Revenues
	Net investment income (loss)	$	248		$	—		$	(2	)
	Net realized and unrealized gains (losses)	1,957			(1,511		)	(74		)
	Other income	10,200			10,200			11,083
		12,405			8,689			11,007
	Expenses
	General and administrative expenses	61,325			48,017			17,923
	Net foreign exchange (gains) losses	(1		)	—			2
	Interest expense	40,968			36,188			36,174
	Total expenses	102,292			84,205			54,099
	Net loss before equity in net income of subsidiaries	(89,887		)	(75,516		)	(43,092		)
	Equity in net income of subsidiaries	438,337			387,431			205,608
	Net income	348,450			311,915			162,516
	Preferred dividends	(32,750		)	(32,750		)	(32,750		)
	Net income available to common and participating common shareholders	$	315,700		$	279,165		$	129,766
	See accompanying notes to the consolidated financial statements
	SCHEDULE II
	ENDURANCE SPECIALTY HOLDINGS LTD.
	CONDENSED FINANCIAL STATEMENT INFORMATION OF THE REGISTRANT, Cont’d.
	STATEMENTS OF CASH FLOWS-PARENT ONLY
	YEARS ENDED DECEMBER 31, 2014, 2013, AND 2012
	(In thousands of United States dollars)
		2014			2013			2012
	Cash flows used in operating activities:
	Net income	$	348,450		$	311,915		$	162,516
	Adjustments to reconcile net income to net cash used in operating activities:
	Depreciation and amortization	6,785			1,504			1,095
	Net realized and unrealized (gains) losses	(1,957		)	1,511			74
	Stock-based compensation expense	15,093			20,708			4,819
Equity in net earnings of subsidiary	(438,337		)	(387,431		)	(205,608		)
Other assets	(177		)	2,112			(2,614		)
Other liabilities	1,626			2,942			(2,136		)
Net cash used in operating activities	(68,517		)	(46,739		)	(41,854		)
Cash flows provided by investing activities:
Proceeds from sale of available for sale investments	26,094			—			—
Purchases of available for sale investments	(24,137		)	—			—
Contributions of capital made to subsidiaries	—			(10,389		)	—
Returns of capital received from subsidiaries	—			10,289			—
Dividends received from subsidiary	145,203			118,278			126,550
Net amounts received from subsidiaries	14,819			7,650			21,760
Purchases of fixed assets	—			(8,298		)	—
Proceeds from disposals of fixed assets	19			—			—
Net cash provided by investing activities	161,998			117,530			148,310
Cash flows used in financing activities:
Repayment of long term debt	—			—			(1,072		)
Issuance of common shares	2,305			31,884			2,935
Bridge facility costs paid	(4,750		)	—			—
Repurchase of common shares	—			(14,584		)	(10,005		)
Settlement of restricted shares	(4,039		)	(3,001		)	(3,272		)
Dividends paid on preferred shares	(32,750		)	(32,750		)	(32,750		)
Dividends paid on common shares	(60,524		)	(55,906		)	(53,439		)
Net cash used in financing activities	(99,758		)	(74,357		)	(97,603		)
Net (decrease) increase in cash and cash equivalents	(6,277		)	(3,566		)	8,853
Cash and cash equivalents, beginning of year	6,517			10,083			1,230
Cash and cash equivalents, end of year	$	240		$	6,517		$	10,083
See accompanying notes to the consolidated financial statements

Schedule_III_Supplementary_Ins

Schedule III Supplementary Insurance Information	12 Months Ended
	Dec. 31, 2014
Supplementary Insurance Information [Abstract]
Schedule III Supplementary Insurance Information	SCHEDULE III
	ENDURANCE SPECIALTY HOLDINGS LTD. AND SUBSIDIARIES
	SUPPLEMENTARY INSURANCE INFORMATION
	YEARS ENDED DECEMBER 31, 2014, 2013, AND 2012
	(In thousands of United States dollars)
	Year Ended December 31, 2014
			Insurance		Reinsurance		Total
	Deferred Acquisition Costs		$	34,581	$	172,787	$	207,368
	Reserve for Losses and Loss Expenses		2,123,772		1,723,087		3,846,859
	Unearned Premiums		642,779		611,740		1,254,519
	Net Premiums Earned		833,912		1,030,066		1,863,978
	Net Investment Income (1)		—		—		131,543
	Net Losses and Loss Expenses		594,561		375,601		970,162
	Amortization of Deferred Acquisition Costs		65,368		254,145		319,513
	Other Operating Expenses (2)		174,575		139,012		313,587
	Net Premiums Written		860,406		1,073,800		1,934,206
	-1	Because the Company does not manage its assets by segment, investment income is not allocated to the individual segments.
	-2	General and administrative expenses incurred by segments are allocated directly. Remaining corporate overhead is allocated to segments primarily based on estimated consumption, headcount and other variables deemed relevant to the allocation of such expenses.
	Year Ended December 31, 2013
			Insurance		Reinsurance		Total
	Deferred Acquisition Costs		$	30,095	$	155,932	$	186,027
	Reserve for Losses and Loss Expenses		2,158,890		1,843,369		4,002,259
	Unearned Premiums		452,113		566,738		1,018,851
	Net Premiums Earned		946,474		1,070,010		2,016,484
	Net Investment Income (1)		—		—		166,216
	Net Losses and Loss Expenses		774,425		445,259		1,219,684
	Amortization of Deferred Acquisition Costs		64,778		239,652		304,430
	Other Operating Expenses (2)		157,596		137,310		294,906
	Net Premiums Written		932,510		1,116,423		2,048,933
	-1	Because the Company does not manage its assets by segment, investment income is not allocated to the individual segments.
	-2	General and administrative expenses incurred by segments are allocated directly. Remaining corporate overhead is allocated to segments primarily based on estimated consumption, headcount and other variables deemed relevant to the allocation of such expenses.
	SCHEDULE III
	ENDURANCE SPECIALTY HOLDINGS LTD. AND SUBSIDIARIES
	SUPPLEMENTARY INSURANCE INFORMATION, Cont’d
	YEARS ENDED DECEMBER 31, 2014, 2013, AND 2012
	(In thousands of United States dollars)
	Year Ended December 31, 2012
			Insurance		Reinsurance		Total
	Deferred Acquisition Costs		$	31,620	$	136,632	$	168,252
	Reserve for Losses and Loss Expenses		2,287,052		1,953,824		4,240,876
	Unearned Premiums		449,475		515,769		965,244
	Net Premiums Earned		955,089		1,058,811		2,013,900
	Net Investment Income (1)		—		—		173,326
	Net Losses and Loss Expenses		855,941		665,054		1,520,995
	Amortization of Deferred Acquisition Costs		75,597		227,582		303,179
	Other Operating Expenses (2)		125,108		110,581		235,689
	Net Premiums Written		942,357		1,087,138		2,029,495
	-1	Because the Company does not manage its assets by segment, investment income is not allocated to the individual segments.
	-2	General and administrative expenses incurred by segments are allocated directly. Remaining corporate overhead is allocated to segments primarily based on estimated consumption, headcount and other variables deemed relevant to the allocation of such expenses.

Schedule_IV_Reinsurance

Schedule IV Reinsurance	12 Months Ended
	Dec. 31, 2014
Supplemental Schedule of Reinsurance Premiums for Insurance Companies [Abstract]
Schedule IV Reinsurance	SCHEDULE IV
	ENDURANCE SPECIALTY HOLDINGS LTD. AND SUBSIDIARIES
	REINSURANCE
	FOR THE YEARS ENDED DECEMBER 31, 2014, 2013 AND 2012
	(In thousands of United States dollars)
	Premiums Written	Gross		Ceded to		Assumed		Net Amount		Percentage
				Other		from Other				of Amount
				Companies		Companies				Assumed
										to Net
	Year ended December 31, 2014
	Property and liability insurance	$	1,716,128	$	959,870	$	1,177,948	$	1,934,206	61	%
	Year ended December 31, 2013
	Property and liability insurance	$	1,475,429	$	616,311	$	1,189,815	$	2,048,933	58	%
	Year ended December 31, 2012
	Property and liability insurance	$	1,429,930	$	519,531	$	1,119,096	$	2,029,495	55	%

Schedule_VI_Underwriters

Schedule VI Underwriters	12 Months Ended
	Dec. 31, 2014
Supplemental Information for Property, Casualty Insurance Underwriters [Abstract]
Schedule of Supplemental Information for Property, Casualty Insurance Underwriters [Text Block]	SCHEDULE VI
	ENDURANCE SPECIALTY HOLDINGS LTD. AND SUBSIDIARIES
	SUPPLEMENTARY INFORMATION FOR PROPERTY AND CASUALTY
	INSURANCE UNDERWRITERS
	FOR THE YEARS ENDED DECEMBER 31, 2014, 2013, AND 2012
	(In thousands of United States dollars)
	Year Ended December 31, 2014
			Insurance			Reinsurance			Total
	Deferred Acquisition Costs		$	34,581		$	172,787		$	207,368
	Reserve for Losses and Loss Expenses		2,123,772			1,723,087			3,846,859
	Discount if any, Reserve for Losses and Loss Expenses		—			—			—
	Unearned Premiums		642,779			611,740			1,254,519
	Net Premiums Earned		833,912			1,030,066			1,863,978
	Net Investment Income (1)		—			—			131,543
	Net Losses and Loss Expenses
	Current Year		675,131			528,846			1,203,977
	Prior Year		(80,570		)	(153,245		)	(233,815		)
	Amortization of Deferred Acquisition Costs		65,368			254,145			319,513
	Paid Losses and Loss Expenses		700,576			457,636			1,158,212
	Net Premiums Written		860,406			1,073,800			1,934,206
	-1	Because the Company does not manage its assets by segment, investment income is not allocated to the individual segments.
	Year Ended December 31, 2013
			Insurance			Reinsurance			Total
	Deferred Acquisition Costs		$	30,095		$	155,932		$	186,027
	Reserve for Losses and Loss Expenses		2,158,890			1,843,369			4,002,259
	Discount if any, Reserve for Losses and Loss Expenses		—			—			—
	Unearned Premiums		452,113			566,738			1,018,851
	Net Premiums Earned		946,474			1,070,010			2,016,484
	Net Investment Income (1)		—			—			166,216
	Net Losses and Loss Expenses
	Current Year		808,328			633,748			1,442,076
	Prior Year		(33,903		)	(188,489		)	(222,392		)
	Amortization of Deferred Acquisition Costs		64,778			239,652			304,430
	Paid Losses and Loss Expenses		797,310			564,782			1,362,092
	Net Premiums Written		932,510			1,116,423			2,048,933
	-1	Because the Company does not manage its assets by segment, investment income is not allocated to the individual segments.
	SCHEDULE VI
	ENDURANCE SPECIALTY HOLDINGS LTD. AND SUBSIDIARIES
	SUPPLEMENTARY INFORMATION FOR PROPERTY AND CASUALTY
	INSURANCE UNDERWRITERS, Cont’d.
	FOR THE YEARS ENDED DECEMBER 31, 2014, 2013, AND 2012
	(In thousands of United States dollars)
	Year Ended December 31, 2012
			Insurance			Reinsurance			Total
	Deferred Acquisition Costs		$	31,620		$	136,632		$	168,252
	Reserve for Losses and Loss Expenses		2,287,052			1,953,824			4,240,876
	Discount if any, Reserve for Losses and Loss Expenses		—			—			—
	Unearned Premiums		449,475			515,769			965,244
	Net Premiums Earned		955,089			1,058,811			2,013,900
	Net Investment Income(1)		—			—			173,326
	Net Losses and Loss Expenses
	Current Year		902,127			739,025			1,641,152
	Prior Year		(46,186		)	(73,971		)	(120,157		)
	Amortization of Deferred Acquisition Costs		75,597			227,582			303,179
	Paid Losses and Loss Expenses		715,309			608,447			1,323,756
	Net Premiums Written		942,357			1,087,138			2,029,495
	-1	Because the Company does not manage its assets by segment, investment income is not allocated to the individual segments.

Summary_Of_Significant_Account1

Summary Of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Premiums And Related Expenses
	(a)	Premiums and related expenses
	The Company’s insurance premiums are earned pro rata over the term of the applicable risk period specified in the insurance policy. The Company’s insurance policies cover losses occurring or claims made during the term of the policy. Generally, the Company receives a fixed premium which is identified in the policy and is recorded on the inception date of the contract or when premiums are determinable and earned evenly over the policy term. This premium will only adjust if the underlying insured values adjust. Accordingly, the Company monitors the underlying insured values and records additional or return premiums in the period in which amounts are reasonably determinable.
	The Company’s reinsurance premiums are earned in proportion to the amount of reinsurance protection provided over the applicable risk period established in the reinsurance contract. Reinsurance contracts written on a losses occurring basis cover losses which occur during the term of the reinsurance contract, typically 12 months. Accordingly, the Company earns the premium on a losses occurring reinsurance contract evenly over the reinsurance contract term. Reinsurance contracts written on a policies attaching basis cover losses from the underlying insurance policies incepting during the terms of the reinsurance contracts. Losses under a policies attaching reinsurance contract may occur after the end date of the reinsurance contract, so long as they are losses from policies that began during the reinsurance contract period. The Company typically earns the premiums for policies attaching reinsurance contracts over a 24-month period in proportion to the amount of reinsurance protection provided to reflect the extension of the risk period past the term of the contract and the varying levels of reinsurance protection provided during the reinsurance contract period.
	In addition to the applicable risk period, the Company’s estimate of its reinsurance premiums written is based on the type of reinsurance contracts underwritten. For excess of loss reinsurance contracts, the deposit premium, as defined in the contract, is generally considered to be the best estimate of the reinsurance contract’s written premium at inception. The Company earns reinstatement premiums upon the occurrence of a loss under the reinsurance contract. Reinstatement premiums are calculated in accordance with the contract terms based upon the ultimate loss estimate associated with each contract. For proportional reinsurance contracts, the Company estimates premium, commissions and related expenses based on broker and ceding company estimates and also utilizes judgment in establishing proportional reinsurance contract estimates.
	2.     Significant accounting policies, cont'd.
	(a)	Premiums and related expenses, cont'd.
	Premiums on the Company’s excess of loss and proportional reinsurance contracts are estimated at the time the business is underwritten. Accordingly, this is the amount the Company records as written premium in the period the reinsurance contract is underwritten. As actual premiums are reported by the ceding companies, management evaluates the appropriateness of the original premium estimates and any adjustments to these estimates are recorded in the period in which they become known.
	Premiums receivable are recorded at amounts due less any allowance for estimated uncollectible premiums receivable. At December 31, 2014, the Company had an allowance for estimated uncollectible premiums receivable of $2.6 million (2013 - $2.3 million).
	Acquisition expenses are costs that vary with and are directly related to the successful production of new and renewal business, and consist principally of commissions and brokerage expenses. Acquisition and general and administrative expenses are shown net of commissions, other fees and expense allowances associated with and earned on ceded business. These costs are deferred and amortized over the periods in which the related premiums are earned. Deferred acquisition costs are limited to their estimated realizable value based on the related unearned premiums. Anticipated net investment income is considered in determining the recoverability of deferred acquisition costs.
Reserve For Losses And Loss Expenses
	(b)	Reserve for losses and loss expenses
	The Company’s reserve for losses and loss expenses includes case reserves and reserves for losses incurred but not reported (referred to as “IBNR reserves”). Case reserves are established for losses that have been reported, but not yet paid. IBNR reserves represent a provision for claims that have been incurred but not yet reported to the Company, as well as future loss development on losses already reported, in excess of the case reserves. Case reserves and IBNR reserves are established by management based on reports from reinsurance intermediaries, ceding companies and insureds, and consultations with independent legal counsel. In addition, reserves for IBNR losses and loss expenses are established by management based on reported losses and loss expenses, and actuarially determined estimates of ultimate losses and loss expenses.
	The Company uses a variety of actuarial methods to estimate the ultimate losses and loss expenses incurred by the Company. One actuarial method used by the Company to estimate reserves for losses and loss expenses is the expected loss ratio approach, which is based on expected results independent of current loss reporting activity. This approach is typically used for immature loss periods (i.e., the current accident year). Another actuarial method used by the Company to estimate reserves for losses and loss expenses is known as the Bornhuetter-Ferguson method. The Bornhuetter-Ferguson method uses an initial loss estimate (expected loss technique) for each accident year by business line and type of contract. Under this method, IBNR is set equal to the initial loss estimate multiplied by the expected percent of loss yet to be reported at each valuation date. In a given quarter, if reported losses are less than expected, then the difference would result in a decrease in estimated ultimate losses. If losses are greater than expected, then the difference would result in an increase in estimated ultimate losses. A third actuarial method used by the Company to estimate reserves for losses and loss expenses is known as the loss development method. The loss development method extrapolates the current value of reported losses to ultimate expected losses by using selected reporting patterns of losses over time. The selected reporting patterns are based on historical information (organized into loss development triangles) and are adjusted to reflect the changing characteristics of the book of business written by the Company. Management uses these multiple actuarial methods, supplemented with professional judgment, to establish the best estimate of reserves for losses and loss expenses.
	The Company’s loss and loss expense reserves are reviewed regularly, and adjustments, if any, are reflected in earnings in the period in which they become known. The establishment of new loss and loss expense reserves or the adjustment of previously recorded loss and loss expense reserves could result in significant positive or negative changes to the Company’s financial condition for any particular period. While management believes the Company’s estimate of loss and loss expense reserves is reasonable, the ultimate loss experience may not be reliably predicted, and it is possible losses and loss expenses may be materially different than the total reserve for losses and loss expenses recorded by the Company.
	Reserves for losses and loss expenses are based in part upon the estimation of losses resulting from catastrophic events. Estimation of these losses and loss expenses are based upon the Company’s historical claims experience and is inherently difficult because of the Company’s short operating history and the possible severity of catastrophe claims. Therefore, the Company uses both proprietary and commercially available models, as well as historical reinsurance industry catastrophe claims experience in addition to its own historical data for purposes of evaluating trends and providing an estimate of ultimate claims costs.
Reinsurance
	(c)	Reinsurance
	Reinsurance recoverable on paid and unpaid losses represent estimates of losses and loss expenses that will be recovered from reinsurers. Amounts recoverable from reinsurers are estimated in a manner consistent with the provisions of the reinsurance agreements and consistent with the establishment of the Company’s reserve for losses and loss expenses. Ceding commissions earned on ceded business are classified as an offset to acquisition and general and administrative expenses.
	The Company purchases reinsurance to reduce its exposure to risk of loss in certain insurance and reinsurance lines of business. Reinsurance recoverables are recorded as assets if the reinsurer is deemed able to meet its obligations. Ceded reinsurance contracts do not relieve the Company from its obligations to policyholders. The Company remains primarily liable to its policyholders for the portion reinsured to the extent that any reinsurer does not meet the obligations assumed under the reinsurance agreements.
Investments
	(d)	Investments
	The Company currently classifies its fixed maturity investments, short-term investments and equity securities as “available for sale” and, accordingly, they are carried at estimated fair value, with related net unrealized gains or losses excluded from earnings and included in shareholders’ equity as a component of accumulated other comprehensive income. Investment transactions are recorded on a trade date basis. The Company determines the fair value of its available for sale investments 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 use of valuation techniques for any given investment requires a significant amount of judgment and consideration of factors specific to the underlying investment. Fair value measurements determined by the Company seek to maximize observable inputs and minimize the use of unobservable inputs. Current accounting guidance establishes three levels as follows:
	Level 1: Unadjusted quoted prices in active markets for identical assets or liabilities.
	Level 2: Quoted prices for similar assets in markets that are active, quoted prices for identical or similar assets in markets that are not active or inputs that are observable either directly or indirectly. Level 2 inputs include quoted prices for similar assets or liabilities other than quoted prices in Level 1; quoted prices in markets that are not active; or other inputs that are observable or can be derived principally from or corroborated by observable market data for substantially the full term of the assets or liabilities.
	Level 3: Unobservable inputs that are supported by little or no market activity and are significant to the fair value of the assets or liabilities. Unobservable inputs reflect the Company’s own views about the assumptions that market participants would use in pricing the asset or liability. Level 3 assets and liabilities include financial instruments whose values are determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant judgment or estimation.
	The Company determines the estimated fair value of each individual security utilizing the highest level inputs available. Transfers between levels are assumed to occur at the end of each period.
	If the Company has the intent to sell a fixed maturity or short-term security in an unrealized loss position or it is more likely than not that the Company will be required to sell the security, the Company deems the security to be other-than-temporarily impaired and writes down the carrying value of the security to fair value, thereby establishing a new cost basis. The amount of the write-down is recognized in earnings as an other-than-temporary impairment (“OTTI”) loss.
	For fixed maturity and short-term investments in an unrealized loss position for which a decision to sell has not been made and it is not more likely than not that the Company will be required to sell the security, the Company performs additional reviews to determine whether the investment will recover its amortized cost.
	If the amortized cost of the Company’s fixed maturity and short-term investments is, based upon the judgment of management, unlikely to be recovered, the Company writes down the investment by the amount representing the credit related portion of the decline in value, thereby establishing a new cost basis. The amount of the write-down is recognized in earnings as an OTTI loss. The new cost basis is not changed for subsequent recoveries in fair value.
	2.     Significant accounting policies, cont'd.
	(d)	Investments, cont'd.
	To the extent the Company determines that the amortized cost of the Company’s fixed maturity and short-term investments is likely to be recovered and the decline in value is related to non-credit factors (such as interest rates, market conditions, etc.) and not due to credit related factors, that remaining non-credit portion of the unrealized loss is recorded as a part of accumulated other comprehensive income in the shareholders’ equity section of the Company’s Consolidated Balance Sheets.
	For equity securities, the Company considers its ability and intent to hold the equity security in an unrealized loss position for a reasonable period of time to allow for a full recovery. When the Company determines that the decline in value of an equity security is other-than-temporary, the Company reduces the cost of the equity security to its fair value and recognizes the loss in the Consolidated Statements of Income and Comprehensive Income. The new cost basis is not changed for subsequent recoveries in fair value.
	Other investments within the Company’s investment portfolio are comprised of (i) hedge funds and private investment funds that generally invest in senior secured bank debt, high yield credit securities, distressed debt, macro strategies, multi-strategy, equity long/short strategies, distressed real estate, and energy sector private equity (“alternative funds”) and (ii) high yield loan funds (“specialty funds”). During 2014, the Company's investment in convertible debt funds previously classified as other investments was merged by the investment manager into a new fund that is classified as an available for sale equity security. Other investments are accounted for using the equity method of accounting whereby the initial investment is recorded at cost. The carrying values of these investments are increased or decreased to reflect the Company’s share of income or loss, which is included in net investment income, and are decreased for dividends. Due to the timing of the delivery of the final valuations reported by the managers of certain of our alternative and specialty funds, our investments in those funds are estimated based on the most recently available information including period end valuation statements, period end estimates, or, in some cases, prior month or quarter valuation statements.
Cash Equivalents And Short-term Investments
	(e)	Cash equivalents and short-term investments
	Cash equivalents include highly liquid short-term deposits and securities with maturities of ninety days or less at the time of purchase. Cash equivalents are valued at amortized cost, which approximates fair value due to the short-term, liquid nature of these securities. Deposits and securities with maturities greater than ninety days and less than one year are classified as short-term investments.
Intangible Assets
	(f)	Intangible assets
	Identifiable intangible assets are amortized in accordance with their useful lives. Goodwill and intangible assets with indefinite useful lives are not amortized but are tested for impairment annually or more often if impairment indicators arise. In making an assessment of the value of its goodwill and intangible assets, the Company uses both market based and non-market based valuations.
	Assumptions underlying these valuations include forecasts of discounted future cash flows and future profits in addition to an analysis of the Company’s stock price relative to both its book value and its net income.
Offering And Registration Costs
	(g)	Offering and registration costs
	Offering and registration costs incurred in connection with equity offerings, including investment banking fees and legal fees, are deducted from the proceeds of the offerings.
Foreign Exchange
	(h)	Foreign exchange
	Assets and liabilities of foreign operations whose functional currency is not the United States dollar are translated at exchange rates in effect at the balance sheet date. Revenues and expenses of such foreign operations are translated at weighted average exchange rates during the year. The effect of the translation adjustments for foreign operations is included in accumulated other comprehensive income, net of applicable deferred income taxes. Other monetary assets and liabilities denominated in foreign currencies are revalued at the exchange rates in effect at the balance sheet date with the resulting net foreign exchange gains and losses included in earnings. Revenues and expenses denominated in foreign currencies are translated at the prevailing exchange rate on the transaction date.
Derivatives
	(i)	Derivatives
	Current accounting guidance requires the recognition of all derivative financial instruments including embedded derivative instruments, as either assets or liabilities in the Consolidated Balance Sheets at fair value.
	The Company may use various derivative instruments such as foreign exchange forward, future and option contracts; interest rate futures, swaps, swaptions, and options; credit default swaps; commodity futures and options; weather swaps and options; and to-be-announced mortgage-backed securities. Except for a cash flow hedge entered into in 2004 as disclosed in Note 8, these derivative instruments are used to manage exposure to interest rate and currency risk, to enhance the efficiency of the Company’s investment portfolio, to economically hedge certain risks, and as part of its weather risk management business. These derivative instruments do not qualify, and are not designated, as hedges. Thus, changes in fair value and any realized gains or losses are recognized in net realized and unrealized gains, net foreign exchange losses (gains), or other underwriting loss in the Consolidated Statements of Income and Comprehensive Income. Margin balances required of counterparties are included in cash and cash equivalents. Where the Company has entered into master netting agreements with counterparties, or the Company has the legal and contractual right to offset positions, the derivative positions may be netted by the counterparty.
Income Taxes
	(j)	Income taxes
	The Company accounts for income taxes for its subsidiaries operating in taxable jurisdictions. Deferred income taxes reflect the net tax effect of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. A valuation allowance is provided when it is more likely than not that some portion of the deferred tax assets will not be realized. The accounting guidance allows for the recognition of tax benefits of uncertain tax positions only where the position is more likely than not to be sustained assuming examination by tax authorities. A liability is established for any tax benefit claimed in a tax return in excess of this threshold. Income tax related interest and penalties are included as income tax expense.
Stock Compensation And Other Stock Plans
	(k)	Stock compensation and other stock plans
	The Company has a share-based employee and non-employee director equity incentive plan (“2007 Equity Incentive Plan”) and other share plans, which are described more fully in Note 15. The fair value of the compensation cost incurred under these plans is measured at the grant date and is expensed over the period for which the employee is required to provide services in exchange for the award. Forfeiture benefits are estimated at the time of grant and incorporated in the determination of share-based compensation costs. Awards under the 2007 Equity Incentive Plan generally vest over four years for employees and one year for non-employee directors.
Earnings Per Share
	(l)	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 (or accumulated) 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 warrants, 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 warrants and options and the vesting or conversion of all convertible securities such as unvested restricted shares using the two-class method described above.
Use Of Estimates
	(m)	Use of estimates
	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported and disclosed amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Variable Interest Entity
	(n)	Variable interest entity
	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 characteristic 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. See also Note 3.
Reclassifications
	(o)	Reclassifications
	Certain comparative information has been reclassified to conform to current year presentation.
Recently Adopted Accounting Pronouncements
	(p)	Recent accounting pronouncements
	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)	12 Months Ended
	Dec. 31, 2014
Investments [Abstract]
Other Investments	In addition to the Company’s fixed maturity, short-term and equity investments, the Company invests in (i) hedge funds and private investment funds that generally invest in senior secured bank debt, high yield credit securities, distressed debt, macro strategies, multi-strategy, equity long/short strategies, distressed real estate, and energy sector private equity (“alternative funds”) and (ii) high yield loan funds (“specialty funds”). During 2014, the Company's investment in convertible debt funds previously classified as other investments was merged by the investment manager into a new fund that is classified as an available for sale equity security. The Company’s alternative funds and specialty funds are recorded on the Company’s balance sheet as “other investments”.
Gain Loss On Investments	Realized and unrealized gains and losses are recognized in earnings using the first in, first out method.

Fair_Value_Measurement_Policy

Fair Value Measurement (Policy)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Of Financial Instruments	The Company determines the fair value of the fixed maturity investments, short-term investments, equity securities, other investments, debt, and other assets and liabilities in accordance with current accounting guidance, which defines fair value and establishes a fair value hierarchy based on inputs to the various valuation techniques used for each fair value measurement. The Company determines the estimated fair value of each individual security utilizing the highest level inputs available. Valuation inputs by security type may include the following:
	•	Government and agencies fixed maturity securities – These securities are generally priced by pricing services or index providers. The pricing services or index providers may use current market trades for securities with similar quality, maturity and coupon. If no such trades are available, the pricing service typically uses analytical models which may incorporate option adjusted spreads, daily interest rate data and market/sector news. The Company generally classifies the fair values of government and agencies securities in Level 2. Current issue U.S. government securities are generally valued based on Level 1 inputs, which use the market approach valuation technique.
	4.     Fair value measurement, cont'd.
	•	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 credit 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, 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.
	4.     Fair value measurement, cont'd.
	•	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 December 31, 2014 and 2013.

Reserve_For_Losses_And_Loss_Ex1

Reserve For Losses And Loss Expenses Reserve For Losses And Loss Expenses (Policies)	12 Months Ended
	Dec. 31, 2014
Insurance Loss Reserves [Abstract]
Reserve For Losses And Loss Expenses
	(b)	Reserve for losses and loss expenses
	The Company’s reserve for losses and loss expenses includes case reserves and reserves for losses incurred but not reported (referred to as “IBNR reserves”). Case reserves are established for losses that have been reported, but not yet paid. IBNR reserves represent a provision for claims that have been incurred but not yet reported to the Company, as well as future loss development on losses already reported, in excess of the case reserves. Case reserves and IBNR reserves are established by management based on reports from reinsurance intermediaries, ceding companies and insureds, and consultations with independent legal counsel. In addition, reserves for IBNR losses and loss expenses are established by management based on reported losses and loss expenses, and actuarially determined estimates of ultimate losses and loss expenses.
	The Company uses a variety of actuarial methods to estimate the ultimate losses and loss expenses incurred by the Company. One actuarial method used by the Company to estimate reserves for losses and loss expenses is the expected loss ratio approach, which is based on expected results independent of current loss reporting activity. This approach is typically used for immature loss periods (i.e., the current accident year). Another actuarial method used by the Company to estimate reserves for losses and loss expenses is known as the Bornhuetter-Ferguson method. The Bornhuetter-Ferguson method uses an initial loss estimate (expected loss technique) for each accident year by business line and type of contract. Under this method, IBNR is set equal to the initial loss estimate multiplied by the expected percent of loss yet to be reported at each valuation date. In a given quarter, if reported losses are less than expected, then the difference would result in a decrease in estimated ultimate losses. If losses are greater than expected, then the difference would result in an increase in estimated ultimate losses. A third actuarial method used by the Company to estimate reserves for losses and loss expenses is known as the loss development method. The loss development method extrapolates the current value of reported losses to ultimate expected losses by using selected reporting patterns of losses over time. The selected reporting patterns are based on historical information (organized into loss development triangles) and are adjusted to reflect the changing characteristics of the book of business written by the Company. Management uses these multiple actuarial methods, supplemented with professional judgment, to establish the best estimate of reserves for losses and loss expenses.
	The Company’s loss and loss expense reserves are reviewed regularly, and adjustments, if any, are reflected in earnings in the period in which they become known. The establishment of new loss and loss expense reserves or the adjustment of previously recorded loss and loss expense reserves could result in significant positive or negative changes to the Company’s financial condition for any particular period. While management believes the Company’s estimate of loss and loss expense reserves is reasonable, the ultimate loss experience may not be reliably predicted, and it is possible losses and loss expenses may be materially different than the total reserve for losses and loss expenses recorded by the Company.
	Reserves for losses and loss expenses are based in part upon the estimation of losses resulting from catastrophic events. Estimation of these losses and loss expenses are based upon the Company’s historical claims experience and is inherently difficult because of the Company’s short operating history and the possible severity of catastrophe claims. Therefore, the Company uses both proprietary and commercially available models, as well as historical reinsurance industry catastrophe claims experience in addition to its own historical data for purposes of evaluating trends and providing an estimate of ultimate claims costs.

Reinsurance_Policy

Reinsurance (Policy)	12 Months Ended
	Dec. 31, 2014
Reinsurance Transactions [Abstract]
Reinsurance
	(c)	Reinsurance
	Reinsurance recoverable on paid and unpaid losses represent estimates of losses and loss expenses that will be recovered from reinsurers. Amounts recoverable from reinsurers are estimated in a manner consistent with the provisions of the reinsurance agreements and consistent with the establishment of the Company’s reserve for losses and loss expenses. Ceding commissions earned on ceded business are classified as an offset to acquisition and general and administrative expenses.
	The Company purchases reinsurance to reduce its exposure to risk of loss in certain insurance and reinsurance lines of business. Reinsurance recoverables are recorded as assets if the reinsurer is deemed able to meet its obligations. Ceded reinsurance contracts do not relieve the Company from its obligations to policyholders. The Company remains primarily liable to its policyholders for the portion reinsured to the extent that any reinsurer does not meet the obligations assumed under the reinsurance agreements.

Derivatives_Policy

Derivatives (Policy)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Accounting policy for derivatives	None of the Company’s derivatives are designated as hedges under current accounting guidance, with the exception of the interest rate lock. The Company invests a portion of its fixed maturity assets with a third party investment manager 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 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 its 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 the overall investment strategy. TBAs represent commitments to purchase or sell a future issuance of agency mortgage-backed securities. For the period between the purchase of a TBA and issuance of the underlying securities, the Company’s position is accounted for as a derivative.
	Energy and Weather Contracts - to address weather and energy risks. The Company may purchase or sell contracts with financial settlements based on the performance of an index linked to a quantifiable weather element, such as temperature, precipitation, snowfall or windspeed, and structures with multiple risk triggers indexed to a quantifiable weather element and a weather sensitive commodity price, such as temperature and electrical power or natural gas. Generally, the Company’s current portfolio of energy and weather derivative contracts is of comparably short duration and such contracts are predominantly seasonal in nature.
Offsetting of derivatives policy	At December 31, 2014 and 2013, none of the Company’s derivative instruments were recorded on a net basis in the Consolidated Balance Sheets.

Segment_Reporting_Policy

Segment Reporting (Policy)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Segment Reporting	The determination of the Company’s business segments is based on how the Company monitors the performance of its underwriting operations. The Company has two reportable business segments, Insurance and Reinsurance.
	•	Insurance – This segment is comprised of four lines of business: agriculture, casualty and other specialty, professional lines, and property, marine and energy. The agriculture line of business is comprised of multi-peril crop insurance, crop hail, livestock risk protection and other agriculture risk management products. The casualty and other specialty line of business is comprised of the insurance and facultative reinsurance of third party liability exposures, including casualty and healthcare liability. The professional line of business includes directors’ and officers’ liability, errors and omissions, employment practices liability, environmental liability and pension trust liability insurance. The property, marine and energy line of business is comprised of the insurance and facultative reinsurance of commercial properties, inland marine and ocean marine insurance, and energy insurance.
	•	Reinsurance – This segment is comprised of five lines of business: catastrophe, property, casualty, professional lines, and specialty. The catastrophe line of business includes reinsurance for catastrophic perils on a treaty basis. The property line of business includes proportional and excess of loss reinsurance of personal and commercial exposures. The casualty line of business is comprised of third party liability exposures, clash and workers’ compensation coverages. The professional line of business includes directors’ and officers’ liability, errors and omissions, employment practices liability, environmental liability and pension trust liability reinsurance. The specialty line of business includes the reinsurance of aviation and space business and proportional and non-proportional reinsurance of hull and cargo insurance business, and proportional and excess of loss coverages of contract and commercial surety business, personal accident coverages, political risk coverages, weather risk management products and agriculture coverages for weather related perils as well as protection from yield and price risks.
	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 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.
	The Company attributes gross premiums written to the geographic region in which the risks originate.

StockBased_Employee_Compensati1

Stock-Based Employee Compensation And Other Stock Plans (Policy)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share Based Compensation RSU Plans [Policy]	The Company uses the Black-Scholes-Merton formula to estimate the value of stock options granted.
	The Company has issued restricted shares and restricted share units to employees and non-employee directors. The fair value of the restricted shares and restricted share units granted was equal to the fair market value of the Company’s ordinary shares on the grant date. Compensation equal to the fair market value of the restricted shares and restricted share units at the measurement date is amortized and charged to income over the vesting period. Restricted shares granted to employees generally vest pro rata over a four-year period. Restricted shares are forfeited upon departure from the Company for any reason prior to the applicable vesting date other than in cases where an employee meets certain retirement eligibility criteria which allow for continuing post-employment vesting of restricted shares, subject to compliance with certain non-competition obligations.
	The 708,890 restricted shares awarded to Mr. Charman, as discussed above, will vest annually, in five equal tranches commencing on May 28, 2013, subject to Mr. Charman’s continued employment, or in the event of certain terminations of employment and other events.
	Restricted shares granted to non-employee directors vest twelve months following the date of grant and are forfeited upon departure from the Board of Directors for any reason prior to the applicable vesting date.
	The Company has granted restricted share units in an amount equal to the dividends that would have been paid on the notional amount of certain options held by employees of the Company. These restricted share units vest and settle on the first March 1st following the six-month anniversary of the date of issuance of the unit.
	The Company generally withholds an amount sufficient to satisfy any federal, state or local withholding tax requirements associated with the vesting of the restricted shares and the restricted share units held by employees.

Investments_Tables

Investments (Tables)	12 Months Ended
	Dec. 31, 2014
Investments [Abstract]
Composition Of Net Investment Income	The components of net investment income for the years ended December 31, 2014, 2013 and 2012 are as follows:
			2014			2013				2012
	Available for sale investments		$	123,773		$	113,074			$	135,841
	Other investments		19,609			64,321				49,059
	Cash and cash equivalents		2,445			2,752				1,616
			$	145,827		$	180,147			$	186,516
	Investment expenses		(14,284		)	(13,931		)		(13,190		)
	Net investment income		$	131,543		$	166,216			$	173,326
Composition Of The Investment Portfolio By Investment Type	The following table summarizes the composition of the investment portfolio by investment type at December 31, 2014 and 2013:
			31-Dec-14						31-Dec-13
	Type of Investment		Fair Value			Percentage			Fair Value				Percentage
	Fixed maturity securities		$	5,092,581		77.1	%		$	4,823,964			74.2	%
	Cash and cash equivalents(1)		632,667			9.6	%		771,714				11.9	%
	Other investments(2)		541,454			8.2	%		617,478				9.5	%
	Short-term investments		9,014			0.1	%		35,028				0.5	%
	Equity securities		331,368			5	%		252,466				3.9	%
	Total		$	6,607,084		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	The following table summarizes the composition by investment rating of the fixed maturity and short-term investments at December 31, 2014 and 2013. In some cases, where bonds are unrated, the rating of the issuer has been applied.
			31-Dec-14						31-Dec-13
	Ratings(1)		Fair Value			Percentage			Fair Value				Percentage
	U.S. government and agencies securities		$	587,411		11.5	%		$	769,343			15.8	%
	AAA/Aaa		1,206,252			23.6	%		972,820				20	%
	AA/Aa		1,717,343			33.7	%		1,771,156				36.5	%
	A/A		1,045,301			20.5	%		895,549				18.4	%
	BBB		427,018			8.4	%		363,722				7.5	%
	Below BBB		96,244			1.9	%		66,791				1.4	%
	Not rated		22,026			0.4	%		19,611				0.4	%
	Total		$	5,101,595		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 (“S&P”). If a rating is not supplied by S&P, 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	Contractual maturities of the Company’s fixed maturity and short-term investments are shown below as of December 31, 2014 and 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.
			31-Dec-14							31-Dec-13
			Amortized			Fair Value				Amortized				Fair Value
			Cost							Cost
	Due within one year		$	126,921		$	127,821			$	144,814			$	145,653
	Due after one year through five years		1,627,154			1,632,259				1,808,001				1,815,240
	Due after five years through ten years		474,959			479,138				290,391				288,486
	Due after ten years		43,314			46,720				26,344				26,937
	Residential mortgage-backed securities		1,149,536			1,175,006				1,192,085				1,187,191
	Commercial mortgage-backed securities		960,598			979,419				932,263				947,677
	Collateralized loan and debt obligations		247,510			248,011				92,519				94,552
	Asset-backed securities		411,529			413,221				351,192				353,256
	Total		$	5,041,521		$	5,101,595			$	4,837,609			$	4,858,992
Other Investments	The following table summarizes the composition and redemption restrictions of other investments as of December 31, 2014 and 2013:
	31-Dec-14		Market Value			Unfunded				Ineligible for
						Commitments				Redemption in 2015
	Alternative funds
	Hedge funds		$	411,280		$	—			$	10,580
	Private investment funds		74,664			70,542				74,664
	Total alternative funds		$	485,944		$	70,542			$	85,244
	Specialty funds
	High yield loan funds		$	55,510		$	—			$	—
	Total specialty funds		$	55,510		$	—			$	—
	Total other investments		$	541,454		$	70,542			$	85,244
	31-Dec-13		Market Value			Unfunded				Ineligible for
						Commitments				Redemption in 2014
	Alternative funds
	Hedge funds		$	401,438		$	—			$	47,406
	Private investment funds		59,703			57,997				59,703
	Total alternative funds		$	461,141		$	57,997			$	107,109
	Specialty funds
	High yield loan funds		$	111,254		$	—			$	—
	Convertible debt funds		45,083			—				—
	Total specialty funds		$	156,337		$	—			$	—
	Total other investments		$	617,478		$	57,997			$	107,109
Net Realized And Unrealized Investment Gains	The analysis of net realized and unrealized gains and losses, intangible asset impairment loss, and the change in the fair value of investment-related derivative financial instruments for the years ended December 31, 2014, 2013 and 2012 are as follows:
			2014			2013				2012
	Gross realized gains on investment sales		$	35,921		$	40,018			$	77,474
	Gross realized losses on investment sales		(16,515		)	(25,521		)		(6,164		)
	Intangible asset impairment loss(1)		(5,450		)	—				—
	Change in fair value of derivative financial instruments(2)		327			667				829
	Net realized and unrealized gains		$	14,283		$	15,164			$	72,139
	-1	For additional information on the Company's intangible assets, see Note 10.
	-2	For additional information on the Company’s derivative financial instruments, see Note 8.
Amortized Cost, Fair Value, Unrealized Gains and Losses and Non-Credit Other-Than-Temporary Impairments
	December 31, 2013		Amortized			Gross				Gross				Fair Value		Non-Credit
			Cost			Unrealized				Unrealized						OTTI (2)
						Gains				Losses
	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 fund		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 amortized cost, fair value and related gross unrealized gains and losses and non-credit OTTI losses on the Company’s securities classified as available for sale at December 31, 2014 and 2013 are as follows:
	31-Dec-14		Amortized			Gross				Gross				Fair Value		Non-Credit
			Cost			Unrealized				Unrealized						OTTI (2)
						Gains				Losses
	Fixed maturity investments
	U.S. government and agencies securities		$	582,970		$	6,471			$	(2,030	)		$	587,411	$	—
	U.S. state and municipal securities		39,340			191				(118		)		39,413		—
	Foreign government securities		239,217			2,983				(1,664		)		240,536		—
	Government guaranteed corporate securities		47,436			675				(9		)		48,102		—
	Corporate securities		1,354,370			12,742				(5,650		)		1,361,462		—
	Residential mortgage-backed securities		1,149,536			27,542				(2,072		)		1,175,006		(3,233		)
	Commercial mortgage-backed securities		960,598			21,374				(2,553		)		979,419		(5		)
	Collateralized loan and debt obligations(1)		247,510			1,449				(948		)		248,011		—
	Asset-backed securities		411,529			2,265				(573		)		413,221		—
	Total fixed maturity investments		$	5,032,506		$	75,692			$	(15,617	)		$	5,092,581	$	(3,238	)
	Short-term investments		9,015			—				(1		)		9,014		—
	Total fixed income investments		$	5,041,521		$	75,692			$	(15,618	)		$	5,101,595	$	(3,238	)
	Equity securities
	Equity investments		$	176,167		$	29,660			$	(3,292	)		$	202,535	$	—
	Emerging market debt funds		60,826			—				(676		)		60,150		—
	Convertible funds		46,331			—				(220		)		46,111		—
	Preferred equity investments		13,858			2,022				(44		)		15,836		—
	Short-term fixed income fund		6,740			—				(4		)		6,736		—
	Total equity securities		$	303,922		$	31,682			$	(4,236	)		$	331,368	$	—
	-1	Balances include amounts related to collateralized debt obligations held with total fair values of $15.2 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, 2014, the gross unrealized loss related to fixed income investments for which a non-credit OTTI was recognized in accumulated other comprehensive income was nil.
Available For Sale Securities In An Unrealized Loss Position
			Less than 12 months							12 months or greater						Total
	December 31, 2013		Unrealized			Fair				Unrealized				Fair		Unrealized			Fair
			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.
	The following tables summarize, for all available for sale securities in an unrealized loss position at December 31, 2014 and 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
	31-Dec-14		Unrealized			Fair				Unrealized				Fair		Unrealized			Fair
			Losses(1)			Value				Losses(1)				Value		Losses(1)			Value
	Fixed maturity investments
	U.S. government and agencies securities		$	(481	)	$	155,350			$	(1,549	)		$	45,993	$	(2,030	)	$	201,343
	U.S. state and municipal securities		(47		)	3,295				(71		)		6,841		(118		)	10,136
	Foreign government securities		(1,378		)	37,904				(286		)		4,306		(1,664		)	42,210
	Government guaranteed corporate securities		(9		)	4,598				—				—		(9		)	4,598
	Corporate securities		(4,023		)	533,139				(1,627		)		84,278		(5,650		)	617,417
	Residential mortgage-backed securities		(260		)	62,832				(1,812		)		108,899		(2,072		)	171,731
	Commercial mortgage-backed securities		(1,068		)	180,222				(1,485		)		78,412		(2,553		)	258,634
	Collateralized loan and debt obligations		(876		)	176,439				(72		)		6,491		(948		)	182,930
	Asset-backed securities		(415		)	199,205				(158		)		19,095		(573		)	218,300
	Total fixed maturity investments		$	(8,557	)	$	1,352,984			$	(7,060	)		$	354,315	$	(15,617	)	$	1,707,299
	Short-term investments		(1		)	1,953				—				—		(1		)	1,953
	Total fixed income investments		$	(8,558	)	$	1,354,937			$	(7,060	)		$	354,315	$	(15,618	)	$	1,709,252
	Equity securities
	Equity investments		$	(3,292	)	$	53,591			$	—			$	—	$	(3,292	)	$	53,591
	Emerging market debt funds		(676		)	60,150				—				—		(676		)	60,150
	Convertible funds		(220		)	46,111				—				—		(220		)	46,111
	Preferred equity investments		(44		)	4,449				—				—		(44		)	4,449
	Short-term fixed income fund		(4		)	6,736				—				—		(4		)	6,736
	Total equity securities		$	(4,236	)	$	171,037			$	—			$	—	$	(4,236	)	$	171,037
	-1	Gross unrealized losses include unrealized losses on non-OTTI and non-credit OTTI securities recognized in accumulated other comprehensive income at December 31, 2014.
Analysis Of OTTI	The analysis of OTTI for the years ended December 31, 2014, 2013 and 2012 is as follows:
			2014			2013				2012
	Total other-than-temporary impairment losses		$	(625	)	$	(1,616	)		$	(364	)
	Portion of loss recognized in other comprehensive income (loss)		—			—				(483		)
	Net impairment losses recognized in earnings		$	(625	)	$	(1,616	)		$	(847	)
Credit Losses Recognized For Available For Sale Investments In Earnings, OTTI Loss Was Recognized In Accumulated Other Comprehensive Income	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 years ended December 31, 2014, 2013 and 2012 :
			2014			2013				2012
	Beginning balance		$	(1,553	)	$	(2,000	)		$	(2,225	)
	Addition for the amount related to the credit loss for which an other-than-temporary impairment was not previously recognized		—			—				(3		)
	Addition for the amount related to the credit loss for which an other-than-temporary impairment was previously recognized		—			—				(502		)
	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 year		715			447				730
	Ending balance		$	(838	)	$	(1,553	)		$	(2,000	)

Fair_Value_Measurement_Tables

Fair Value Measurement (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Schedule Of Available For Sale Investments, Other Investments, Derivative Instruments and Debt Measured On A Recurring Basis	The following table sets forth the Company’s available for sale investments, other investments, other assets and liabilities and debt categorized by the level within the hierarchy in which the fair value measurements fall at December 31, 2013:
					Fair Value Measurements at December 31, 2013
		Total at December 31, 2013			Quoted			Significant			Significant
					Prices in			Other			Unobservable
					Active			Observable			Inputs
					Markets for			Inputs			(Level 3)
					Identical			(Level 2)
					Assets
					(Level 1)
	Assets
	Fixed maturity investments
	U.S. government and agencies securities	$	769,343		$	20,248		$	749,095		$	—
	U.S. state and municipal securities	26,854			—			26,854			—
	Foreign government securities	182,647			—			182,647			—
	Government guaranteed corporate securities	35,145			—			35,145			—
	Corporate securities	1,227,299			—			1,226,553			746
	Residential mortgage-backed securities	1,187,191			—			1,186,943			248
	Commercial mortgage-backed securities	947,677			—			946,794			883
	Collateralized loan and debt obligations	94,552			—			92,095			2,457
	Asset-backed securities	353,256			—			350,262			2,994
	Total fixed maturity investments	$	4,823,964		$	20,248		$	4,796,388		$	7,328
	Equity securities
	Equity investments	174,669			117,776			56,893			—
	Emerging market debt funds	60,844			—			60,844			—
	Preferred equity investments	8,223			—			8,223			—
	Short-term fixed income fund	8,730			8,730			—			—
	Total equity securities	$	252,466		$	126,506		$	125,960		$	—
	Short-term investments	35,028			—			35,028			—
	Other investments	617,478			—			—			617,478
	Other assets (see Note 8)	108,272			—			94,234			14,038
	Total assets	$	5,837,208		$	146,754		$	5,051,610		$	638,844
	Liabilities
	Other liabilities (see Note 8)	$	49,452		$	—		$	29,883		$	19,569
	Debt	575,115			—			575,115			—
	Total liabilities	$	624,567		$	—		$	604,998		$	19,569
	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, 2014:
					Fair Value Measurements at December 31, 2014
		Total at December 31, 2014			Quoted			Significant			Significant
					Prices in			Other			Unobservable
					Active			Observable			Inputs
					Markets for			Inputs			(Level 3)
					Identical			(Level 2)
					Assets
					(Level 1)
	Assets
	Fixed maturity investments
	U.S. government and agencies securities	$	587,411		$	105,121		$	482,290		$	—
	U.S. state and municipal securities	39,413			—			39,413			—
	Foreign government securities	240,536			—			240,536			—
	Government guaranteed corporate securities	48,102			—			48,102			—
	Corporate securities	1,361,462			—			1,358,960			2,502
	Residential mortgage-backed securities	1,175,006			—			1,174,997			9
	Commercial mortgage-backed securities	979,419			—			974,602			4,817
	Collateralized loan and debt obligations	248,011			—			246,042			1,969
	Asset-backed securities	413,221			—			410,228			2,993
	Total fixed maturity investments	$	5,092,581		$	105,121		$	4,975,170		$	12,290
	Equity securities
	Equity investments	202,535			138,463			64,072			—
	Emerging market debt funds	60,150			—			60,150			—
	Convertible funds	46,111			—			46,111			—
	Preferred equity investments	15,836			—			15,836			—
	Short-term fixed income fund	6,736			6,736			—			—
	Total equity securities	$	331,368		$	145,199		$	186,169		$	—
	Short-term investments	9,014			—			9,014			—
Other investments	541,454			—			—			541,454
Other assets (see Note 8)	99,504			—			73,889			25,615
Total assets	$	6,073,921		$	250,320		$	5,244,242		$	579,359
Liabilities
Other liabilities (see Note 8)	$	54,338		$	—		$	18,972		$	35,366
Debt	623,740			—			623,740			—
Total liabilities	$	678,078		$	—		$	642,712		$	35,366
Fair Value Inputs Assets And Liabilities Quantitative Information [Table Text Block]	Below is a summary of quantitative information regarding the significant observable and unobservable inputs used in determining the fair value of the net weather and energy related derivative liabilities classified in Level 3 that are measured at fair value on a recurring basis at December 31, 2014 and 2013:
		31-Dec-14
		Fair Value			Valuation		Unobservable	Low			High			Weighted Average
		(Level 3)			Techniques		Inputs							or Actual
		(U.S. dollars in thousands, except for correlation and commodity curve)
	Net weather and energy related derivative liabilities	$	9,751		Historical		Correlation	0			1			Actual
					Analysis and
					Simulation
							Weather curve	$	(828	)	$	2,500		Actual
							Commodity curve	$	—		$	—		Actual
		December 31, 2013
		Fair Value (Level 3)			Valuation Techniques		Unobservable	Low			High			Weighted Average
							Inputs							or Actual
		(U.S. dollars in thousands, except for correlation and commodity curve)
	Net weather and energy related derivative liabilities	$	5,531		Historical Analysis and Simulation		Correlation	0			1			Actual
							Weather curve	$	—		$	7,940		Actual
							Commodity curve	$	0.65		$	10		Actual
Reconciliation Of The Beginning And Ending Balances For All Available For Sale Investments, Other Investments And Derivative Instruments Measured At Fair Value On A Recurring Basis Using Level 3 Inputs	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 years ended December 31, 2014 and 2013.
	31-Dec-14	Fixed			Other			Other			Total			Other
		maturity			investments			assets			assets			liabilities
		investments
	Level 3, beginning of year	$	7,328		$	617,478		$	14,038		$	638,844		$	(19,569	)
	Total equity income and realized gains included in earnings	144			58,555			—			58,699			—
	Total equity losses and losses included in earnings	(85		)	(38,947		)	—			(39,032		)	—
	Total income included in other underwriting loss	—			—			32,642			32,642			29,040
	Total loss included in other underwriting loss	—			—			(27,147		)	(27,147		)	(37,617		)
	Change in unrealized gains included in other comprehensive income (loss)	801			—			—			801			—
	Change in unrealized losses included in other comprehensive income (loss)	(706		)	—			—			(706		)	—
	Purchases	842			59,023			2,807			62,672			(1,404		)
	Issues	—			—			15,631			15,631			(25,692		)
	Sales	(1,848		)	(154,655		)	—			(156,503		)	—
	Settlements	—			—			(12,356		)	(12,356		)	19,876
	Transfers into Level 3	13,311			—			—			13,311			—
	Transfers out of Level 3	(7,497		)	—			—			(7,497		)	—
	Level 3, end of year	$	12,290		$	541,454		$	25,615		$	579,359		$	(35,366	)
	4.     Fair value measurement, cont'd.
	31-Dec-13	Fixed			Other			Other			Total			Other
		maturity			investments			assets			assets			liabilities
		investments
	Level 3, beginning of year	$	8,497		$	517,546		$	882		$	526,925		$	(1,922	)
	Total equity income and realized gains included in earnings	127			86,605			—			86,732			—
	Total equity losses and losses included in earnings	(17		)	(22,284		)	—			(22,301		)	—
	Total income included in other underwriting loss	—			—			10,452			10,452			7,340
	Total loss included in other underwriting loss	—			—			(6,927		)	(6,927		)	(11,126		)
	Change in unrealized gains included in other comprehensive income (loss)	749			—			—			749			—
	Change in unrealized losses included in other comprehensive income (loss)	(305		)	—			—			(305		)	—
	Purchases	1,665			67,571			2,994			72,230			(587		)
	Issues	—			—			6,637			6,637			(13,274		)
	Sales	(6,654		)	(31,960		)	—			(38,614		)	—
	Transfers into Level 3	11,729			—			—			11,729			—
	Transfers out of Level 3	(8,463		)	—			—			(8,463		)	—
	Level 3, end of year	$	7,328		$	617,478		$	14,038		$	638,844		$	(19,569	)

Reserve_For_Losses_And_Loss_Ex2

Reserve For Losses And Loss Expenses (Tables)	12 Months Ended
	Dec. 31, 2014
Insurance Loss Reserves [Abstract]
Reserve For Losses And Loss Expenses	Activity in the reserve for losses and loss expenses for the years ended December 31, 2014, 2013 and 2012 is summarized as follows:
		2014			2013			2012
	Gross reserve for losses and loss expenses, January 1	$	4,002,259		$	4,240,876		$	3,824,224
	Reinsurance recoverable on unpaid losses	593,755			691,783			467,934
	Net reserve for losses and loss expenses, January 1	3,408,504			3,549,093			3,356,290
	Incurred related to:
	Current year	1,203,977			1,442,076			1,641,152
	Prior years	(233,815		)	(222,392		)	(120,157		)
	Total incurred	970,162			1,219,684			1,520,995
	Paid related to:
	Current year	(439,169		)	(524,010		)	(608,228		)
	Prior years	(719,043		)	(838,082		)	(715,528		)
	Total paid	(1,158,212		)	(1,362,092		)	(1,323,756		)
	Foreign currency translation and other	(44,390		)	1,819			(4,436		)
	Net reserve for losses and loss expenses, December 31	3,176,064			3,408,504			3,549,093
	Reinsurance recoverable on unpaid losses	670,795			593,755			691,783
	Gross reserve for losses and loss expenses, December 31	$	3,846,859		$	4,002,259		$	4,240,876

Reinsurance_Tables

Reinsurance (Tables)	12 Months Ended
	Dec. 31, 2014
Reinsurance Disclosures [Abstract]
Effects Of Reinsurance On Premiums Written And Earned	The effects of reinsurance on premiums earned and written during the years ended December 31, 2014, 2013 and 2012 are as follows:
		Year Ended December 31, 2014						Year Ended December 31, 2013						Year Ended December 31, 2012
		Earned			Written			Earned			Written			Earned			Written
	Direct	$	1,521,648		$	1,716,128		$	1,472,796		$	1,475,429		$	1,428,765		$	1,429,930
	Assumed	1,132,370			1,177,948			1,139,487			1,189,815			1,087,702			1,119,096
	Ceded	(790,040		)	(959,870		)	(595,799		)	(616,311		)	(502,567		)	(519,531		)
		$	1,863,978		$	1,934,206		$	2,016,484		$	2,048,933		$	2,013,900		$	2,029,495
Losses Recoverable By Rating	The balance of reinsurance recoverable on paid and unpaid losses at December 31, 2014 and 2013 was distributed as follows based on the ratings of the reinsurers:
	Rating	31-Dec-14			31-Dec-13
	U.S. government sponsored program	$	339,617		$	356,049
	A+ and above	294,216			253,665
	A	248,297			135,949
	A- and below	4			2,046
	Not rated	6,952			10,266
	Total	$	889,086		$	757,975

Derivatives_Tables

Derivatives (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule Of The Fair Values And The Related Notional Values Of Derivatives Included In The Company's Consolidated Balance Sheet	The fair values and the related notional values of derivatives at December 31, 2014 and 2013 are noted below.
		31-Dec-14						31-Dec-13
		Fair			Notional			Fair			Notional
		Value			Principal			Value			Principal
					Amount						Amount
	Derivatives recorded in other assets
	Foreign exchange forward contracts	$	651		$	42,694		$	251		$	19,269
	Interest rate swaps	—			—			124			16,100
	Interest rate swaptions	—			—			39			24,338
	Interest rate futures	7			7,595			—			—
	TBAs	73,231			70,000			93,820			93,840
	Energy and weather contracts	25,615			81,624			14,038			53,986
	Total recorded in other assets	$	99,504					$	108,272
	Derivatives recorded in other liabilities
	Foreign exchange forward contracts	$	123		$	20,945		$	172		$	15,861
	Interest rate swaps	20			12,549			933			12,193
	Interest rate swaptions	9			13,100			543			361,455
	Interest rate futures	—			—			17			103,935
	TBAs	18,820			18,000			28,218			28,000
	Energy and weather contracts	35,366			135,050			19,569			66,113
	Total recorded in other liabilities	$	54,338					$	49,452
	Net derivative asset	$	45,166					$	58,820
Schedule Of The Gains And Losses On The Consolidated Statements Of Income And Comprehensive Income From Derivatives	The gains and losses on the Consolidated Statements of Income and Comprehensive Income for derivatives for the years ended December 31, 2014 and 2013 were as follows:
		2014			2013			2012
	Total included in net foreign exchange losses (gains) from foreign exchange forward contracts	$	1,880		$	357		$	98
	Interest rate futures	$	121		$	44		$	87
	Credit default swaps	30			49			48
	Interest rate swaps	(4,239		)	1,241			85
	Interest rate swaptions	477			291			29
	TBAs	3,938			(958		)	580
	Total included in net realized and unrealized gains	$	327		$	667		$	829
	Energy and weather contracts	$	(315	)	$	(261	)	$	—
	Commodity put options	—			—			(2,684		)
	Total included in other underwriting loss	$	(315	)	$	(261	)	$	(2,684	)
	Total gains from derivatives	$	1,892		$	763		$	(1,757	)

Segment_Reporting_Tables

Segment Reporting (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Summary Of The Segment Revenues, Results And Reserve For Losses And Loss Expenses And The Carrying Value Of Goodwill	The following table provides a summary of the segment revenues and results for the year ended December 31, 2014, reserve for losses and loss expenses as of December 31, 2014 and the carrying value of goodwill as of December 31, 2014:
		Insurance			Reinsurance			Total
	Revenues
	Gross premiums written	$	1,716,128		$	1,177,948		$	2,894,076
	Ceded premiums written	(855,722		)	(104,148		)	(959,870		)
	Net premiums written	860,406			1,073,800			1,934,206
	Net premiums earned	833,912			1,030,066			1,863,978
	Other underwriting loss	—			(5,786		)	(5,786		)
		833,912			1,024,280			1,858,192
	Expenses
	Net losses and loss expenses	594,561			375,601			970,162
	Acquisition expenses	65,368			254,145			319,513
	General and administrative expenses	174,575			139,012			313,587
		834,504			768,758			1,603,262
	Underwriting (loss) income	$	(592	)	$	255,522		$	254,930
	Net loss ratio	71.4		%	36.4		%	52.1		%
	Acquisition expense ratio	7.8		%	24.7		%	17.1		%
	General and administrative expense ratio	20.9		%	13.5		%	16.8		%
	Combined ratio	100.1		%	74.6		%	86		%
	Reserve for losses and loss expenses	$	2,123,772		$	1,723,087		$	3,846,859
	Goodwill	$	47,925		$	43,313		$	91,238
	The following table provides a summary of the segment revenues and results for the year ended December 31, 2013, reserve for losses and loss expenses as of December 31, 2013 and the carrying value of goodwill as of December 31, 2013:
		Insurance			Reinsurance			Total
	Revenues
	Gross premiums written	$	1,475,429		$	1,189,815		$	2,665,244
	Ceded premiums written	(542,919		)	(73,392		)	(616,311		)
	Net premiums written	932,510			1,116,423			2,048,933
	Net premiums earned	946,474			1,070,010			2,016,484
	Other underwriting loss	—			(2,046		)	(2,046		)
		946,474			1,067,964			2,014,438
	Expenses
	Net losses and loss expenses	774,425			445,259			1,219,684
	Acquisition expenses	64,778			239,652			304,430
	General and administrative expenses	157,596			137,310			294,906
		996,799			822,221			1,819,020
	Underwriting (loss) income	$	(50,325	)	$	245,743		$	195,418
	Net loss ratio	81.8		%	41.6		%	60.5		%
	Acquisition expense ratio	6.8		%	22.4		%	15.1		%
	General and administrative expense ratio	16.7		%	12.8		%	14.6		%
	Combined ratio	105.3		%	76.8		%	90.2		%
	Reserve for losses and loss expenses	$	2,158,890		$	1,843,369		$	4,002,259
	Goodwill	$	47,925		$	43,368		$	91,293
	The following table provides a summary of the segment revenues and results for the year ended December 31, 2012, reserve for losses and loss expenses as of December 31, 2012 and the carrying value of goodwill as of December 31, 2012:
		Insurance			Reinsurance			Total
	Revenues
	Gross premiums written	$	1,429,930		$	1,119,096		$	2,549,026
	Ceded premiums written	(487,573		)	(31,958		)	(519,531		)
	Net premiums written	942,357			1,087,138			2,029,495
	Net premiums earned	955,089			1,058,811			2,013,900
	Other underwriting (loss) income	(2,684		)	501			(2,183		)
		952,405			1,059,312			2,011,717
	Expenses
	Net losses and loss expenses	855,941			665,054			1,520,995
	Acquisition expenses	75,597			227,582			303,179
	General and administrative expenses	125,108			110,581			235,689
		1,056,646			1,003,217			2,059,863
	Underwriting (loss) income	$	(104,241	)	$	56,095		$	(48,146	)
	Net loss ratio	89.6		%	62.8		%	75.5		%
	Acquisition expense ratio	7.9		%	21.5		%	15.1		%
	General and administrative expense ratio	13.1		%	10.4		%	11.7		%
	Combined ratio	110.6		%	94.7		%	102.3		%
	Reserve for losses and loss expenses	$	2,287,052		$	1,953,824		$	4,240,876
	Goodwill	$	47,925		$	43,014		$	90,939
Schedule Of Segment Results To Income Before Income Taxes	The following table reconciles total segment results to income before income taxes for the years ended December 31, 2014, 2013 and 2012:
		2014			2013			2012
	Total underwriting income (loss)	$	254,930		$	195,418		$	(48,146	)
	Net investment income	131,543			166,216			173,326
	Net foreign exchange (losses) gains	(3,839		)	(14,214		)	15,911
	Net realized and unrealized gains	14,283			15,164			72,139
	Net impairment losses recognized in earnings	(625		)	(1,616		)	(847		)
	Amortization of intangibles	(6,484		)	(7,012		)	(10,347		)
	Interest expense	(40,968		)	(36,188		)	(36,174		)
	Income before income taxes	$	348,840		$	317,768		$	165,862
Schedule Of Gross Premiums Written By Line Of Business	The following table provides gross premiums written by line of business for the years ended December 31, 2014, 2013 and 2012:
	Business Segment	2014			2013			2012
	Insurance
	Agriculture	$	866,025		$	954,389		$	903,730
	Casualty and other specialty	396,113			303,803			296,325
	Professional lines	263,538			148,537			169,815
	Property, marine and energy	190,452			68,700			60,060
	Total Insurance	1,716,128			1,475,429			1,429,930
	Reinsurance
	Catastrophe	343,213			355,751			378,387
	Property	287,326			297,806			349,579
	Casualty	159,533			241,358			208,353
	Professional lines	174,656			163,594			59,076
	Specialty	213,220			131,306			123,701
	Total Reinsurance	1,177,948			1,189,815			1,119,096
	Total	$	2,894,076		$	2,665,244		$	2,549,026
Schedule Of Geographic Distribution Of Gross Premiums Written	The following table provides the geographic distribution of gross premiums written for the years ended December 31, 2014, 2013 and 2012:
		2014			2013			2012
	United States	$	2,054,431		$	1,960,693		$	1,901,686
	Worldwide	456,078			435,655			412,941
	Europe	172,077			153,516			121,363
	Australasia	61,994			25,191			22,497
	Japan	45,618			33,879			36,392
	Canada	19,622			15,403			17,248
	Other	84,256			40,907			36,899
	Total gross premiums written	$	2,894,076		$	2,665,244		$	2,549,026

Goodwill_And_Intangible_Assets1

Goodwill And Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule Of Goodwill And Intangible Assets	The following table shows an analysis of goodwill and intangible assets for the years ended December 31, 2014 and 2013:
		Goodwill			Intangible			Intangible			Total
					assets with			assets with
					indefinite			finite lives
					lives
	Net balance at December 31, 2012	$	90,939		$	17,229		$	63,832		$	172,000
	Additions	354			—			36			390
	Amortization	—			—			(7,012		)	(7,012		)
	Net balance at December 31, 2013	$	91,293		$	17,229		$	56,856		$	165,378
	Additions	(55		)	—			16			(39		)
	Amortization	—			—			(6,484		)	(6,484		)
	Impairment loss	—			(5,450		)	—			(5,450		)
	Net balance at December 31, 2014	$	91,238		$	11,779		$	50,388		$	153,405
	Gross balance	$	91,238		$	17,229		$	138,042		$	246,509
	Accumulated amortization	—			—			(87,654		)	(87,654		)
	Accumulated impairment losses	—			(5,450		)	—			(5,450		)
	Net balance	$	91,238		$	11,779		$	50,388		$	153,405

Commitments_And_Contingencies_

Commitments And Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Schedule Of Percentage Of Net Premiums Written Generated Through Company's Largest Brokers	The following table shows the percentage of net premiums written generated through the Company’s largest brokers for the years ended December 31, 2014, 2013 and 2012:
	Broker		2014		2013		2012
	Marsh & McLennan Companies, Inc.		21.9	%	19.5	%	16.9	%
	Aon Benfield		15.1	%	17.7	%	17.4	%
	Willis Companies		13.2	%	11.9	%	15.8	%
	Total of largest brokers		50.2	%	49.1	%	50.1	%
Schedule Of Future Minimum Lease Commitments	Future minimum lease commitments at December 31, 2014 are as follows:
	Year ending December 31,	Amount
	2015	15,923
	2016	12,779
	2017	11,976
	2018	10,936
	2019	11,386
	2020 and thereafter	33,783
		$	96,783

Shareholders_Equity_Tables

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
Schedule Of Company's Share Capital	The Company’s share capital at December 31, 2014 and 2013 is comprised as follows:
			2014			2013
	Preferred shares
	Authorized – $1.00 par value each		17,200,000			17,200,000
	Issued, outstanding and fully paid:
	Series A preferred shares – $1.00 par value each; aggregate liquidation preference $200,000 (2013 - $200,000)		8,000,000			8,000,000
	Series B preferred shares – $1.00 par value each; aggregate liquidation preference $230,000 (2013 - $230,000)		9,200,000			9,200,000
			17,200,000			17,200,000
	Common shares
	Authorized - $1.00 par value each		120,000,000			120,000,000
	Issued, outstanding and fully paid:
	Ordinary common shares - $1.00 par value each		44,765,153			44,368,742
Schedule Of Accumulated Other Comprehensive Income	The following table presents the changes in accumulated other comprehensive income balances by component for the years ended December 31, 2014 and 2013:
			For the Year Ended December 31, 2014
			Losses on				Unrealized gains			Foreign currency translation			Total
			cash flow hedges				(losses) on available for sale			adjustments
							securities
	Beginning balance		$	(1,855	)		$	45,950		$	18,636		$	62,731
	Other comprehensive income (loss) before reclassifications		—				60,632			(26,264		)	34,368
	Amounts reclassified from accumulated other		89				(20,482		)	—			(20,393		)
	comprehensive income (1)
	Net current period other comprehensive income (loss)		89				40,150			(26,264		)	13,975
	Ending balance		$	(1,766	)		$	86,100		$	(7,628	)	$	76,706
	-1	All amounts are net of tax.
			For the Year Ended December 31, 2013
			Losses on				Unrealized gains			Foreign currency translation			Total
			cash flow hedges				(losses) on available for sale			adjustments
							securities
	Beginning balance		$	(1,944	)		$	141,731		$	12,676		$	152,463
	Other comprehensive income (loss) before reclassifications		—				(83,951		)	5,960			(77,991		)
	Amounts reclassified from accumulated other		89				(11,830		)	—			(11,741		)
	comprehensive income(1)
	Net current period other comprehensive income (loss)		89				(95,781		)	5,960			(89,732		)
	Ending balance		$	(1,855	)		$	45,950		$	18,636		$	62,731
	-1	All amounts are net of tax.
Reclassification Out Of Accumulated Other Comprehensive Income	The following tables present the significant items reclassified out of accumulated other comprehensive income during the years ended December 31, 2014 and 2013:
	For the Year Ended December 31, 2014
	Details about accumulated other		Amount reclassified				Affected line item in the Consolidated Statements
	comprehensive income components		from accumulated				of Income and Comprehensive Income
			other comprehensive
			income
	Losses on cash flow hedges - Debt		$	89			Interest expense
			89				Total before income taxes
			—				Income tax expense
			$	89			Total net of income taxes
	Unrealized (gains) losses on available for sale securities		$	(19,406	)		Net realized and unrealized gains
			625				Net impairment losses recognized in earnings
			(18,781		)		Total before income taxes
			(1,701		)		Income tax benefit
			$	(20,482	)		Total net of income taxes
	For the Year Ended December 31, 2013
	Details about accumulated other		Amount reclassified				Affected line item in the Consolidated Statements
	comprehensive income components		from accumulated				of Income and Comprehensive Income
			other comprehensive
			income
	Losses on cash flow hedges - Debt		$	89			Interest expense
			89				Total before income taxes
			—				Income tax expense
			$	89			Total net of income taxes
	Unrealized (gains) losses on available for sale securities		$	(14,497	)		Net realized and unrealized gains
			1,616				Net impairment losses recognized in earnings
			(12,881		)		Total before income taxes
			1,051				Income tax expense
			$	(11,830	)		Total net of income taxes

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Schedule Of Computation Of Basic And Diluted Earnings Per Share	The following table sets forth the computation of basic and diluted earnings per share for the years ended December 31, 2014, 2013 and 2012:
			2014			2013			2012
	Numerator:
	Net income available to common and participating common shareholders		$	315,700		$	279,165		$	129,766
	Less amount allocated to participating common shareholders (1)		(9,118		)	(6,444		)	(2,113		)
	Net income allocated to common shareholders		$	306,582		$	272,721		$	127,653
	Denominator:
	Weighted average shares - basic		43,368,062			42,817,624			42,567,736
	Share equivalents:
	Options		47,111			—			31,833
	Restricted share units		70			583			2,266
	Weighted average shares - diluted		43,415,243			42,818,207			42,601,835
	Basic earnings per common share		$	7.07		$	6.37		$	3
	Diluted earnings per common share		$	7.06		$	6.37		$	3
	-1	Represents earnings and dividends attributable to holders of unvested restricted shares issued under the Company’s stock compensation plans that are considered participating. In periods of loss, no losses are allocated to participating common shareholders (unvested restricted shares).
Schedule Of Dividends Declared	The following table sets forth dividends declared in the years ended December 31, 2014, 2013 and 2012, respectively:
			2014			2013			2012
	Dividends declared per Series A preferred share		$	1.9375		$	1.9375		$	1.9375
	Dividends declared per Series B preferred share		$	1.875		$	1.875		$	1.875
	Dividends declared per common share		$	1.36		$	1.28		$	1.24

StockBased_Employee_Compensati2

Stock-Based Employee Compensation And Other Stock Plans (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary Of Stock Option Activity	A summary of option activity, including options held by employees and non-employee directors, during the year ended December 31, 2014 is presented below:
		For the year ended December 31, 2014
	Options Outstanding	Number of		Weighted		Weighted	Aggregate
		Options		Average		Average	Intrinsic Value
				Exercise Price		Remaining
						Contractual Life
						(years)
	Beginning of year	815,000		$	47.94
	Granted	—		—
	Exercised	(15,000	)	33.91
	Forfeited	—		—
	Outstanding, end of year	800,000		$	48.2	8.41	$	9,312
	Exercisable and vested options, end of year	320,000		$	48.2	8.41	$	3,725
Restricted Share And Restricted Share Unit Activity	A summary of the restricted share and restricted share unit activity during the year ended December 31, 2014, is presented below:
		Number of		Aggregate
		Shares/Units		Intrinsic Value
	Unvested, beginning of year	1,261,260
	Granted	505,997
	Settled	(402,479	)
	Forfeited	(73,884	)
	Unvested, end of year	1,290,894
	Outstanding, end of year	1,290,894		$	77,247

Statutory_Requirements_And_Div1

Statutory Requirements And Dividend Restrictions (Tables)	12 Months Ended
	Dec. 31, 2014
Statutory Requirements And Dividend Restrictions [Abstract]
Statutory Capital	The combined statutory capital and combined statutory net income (loss) for our principal operating subsidiaries in their respective jurisdictions were as follows:
	Statutory capital		Bermuda(1)					United States					Other(2)
			2014		2013			2014			2013		2014		2013
	Required statutory capital		$	955,903	$	965,348		$	244,587		$	236,652	$	77,366	$	63,369
	Actual statutory capital		2,876,927		2,618,198			702,513			654,480		603,288		512,579
	-1	Bermuda statutory capital includes an investment in affiliate asset, which represents its interest in the remaining insurance and reinsurance operations of the Company included in the United States and Other columns above.
	-2	Includes Endurance U.K. and Endurance Bermuda’s Singapore branch.
Statutory Net Income (Loss)
	Statutory net income (loss)		Bermuda		United States			Other(2)
	Year ended December 31, 2014		$	453,127	$	28,450		$	14,103
	Year ended December 31, 2013		454,840		(48,035		)	(36,678		)
	Year ended December 31, 2012		355,118		(147,325		)	2,829
	-2	Includes Endurance U.K. and Endurance Bermuda’s Singapore branch.

Taxes_Tables

Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Tax Expense	The income tax expense was as follows for the years ended December 31, 2014, 2013 and 2012, respectively:
			2014			2013			2012
	Current income tax expense		$	(1,804	)	$	(3,089	)	$	(5,029	)
	Deferred income tax benefit (expense)		1,414			(2,764		)	1,683
	Income tax expense		$	(390	)	$	(5,853	)	$	(3,346	)
Schedule Of Effective Income Tax Rate Reconciliation	The actual income tax expense attributable to income for the years ended December 31, 2014, 2013 and 2012 differed from the amount computed by applying the combined effective rate of 0% under Bermuda law to income before income taxes, as a result of the following:
			2014			2013			2012
	Computed expected tax expense		$	—		$	—		$	—
	Tax (expense) benefit effect on foreign taxes		(1,661		)	31,054			51,059
	Change in valuation allowance		1,271			(36,907		)	(54,405		)
			$	(390	)	$	(5,853	)	$	(3,346	)
Schedule Of Net Deferred Tax Assets And Liabilities	Net deferred income tax assets and liabilities consisted of the following as of December 31, 2014 and 2013:
			2014			2013
	Deferred income tax assets:
	Unearned premiums		$	23,124		$	22,701
	Loss reserves		29,410			32,109
	Net operating loss carryforward		93,163			106,112
	Deferred compensation		19,588			14,943
	Deferred interest		44,951			43,341
	Realized investment losses		125			150
	Other		10,404			3,388
	Total deferred income tax assets		220,765			222,744
	Deferred income tax liabilities:
	Deferred acquisition costs		(10,843		)	(16,874		)
	Unrealized investment (gains) losses		(5,293		)	30
	Unrealized foreign exchange (gains) losses		(2,704		)	600
	Temporary differences related to acquisition		(20,344		)	(22,612		)
	Start up costs		(1,144		)	(720		)
	Other		(10,033		)	(8,785		)
	Total deferred income tax liabilities		(50,361		)	(48,361		)
	Valuation allowance		(121,409		)	(122,680		)
	Net deferred income tax asset		$	48,995		$	51,703
Schedule Of Distribution Of Income Before Income Taxes	The Company’s income before income taxes was distributed as follows for the years ended December 31, 2014, 2013 and 2012, respectively:
			2014			2013			2012
	U.S. (domestic)		$	60,112		$	13,103		$	(186,882	)
	Non-U.S. (foreign) (1)		288,728			304,665			352,744
	Income before income taxes		$	348,840		$	317,768		$	165,862
	-1	The Company’s non-U.S. (foreign) operating subsidiaries write business that is exposed to risks originating in the United States.

Condensed_Unaudited_Quarterly_1

Condensed Unaudited Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Summary Of The Unaudited Quarterly Data	The following is a summary of the unaudited quarterly data for the year ended December 31, 2014:
		Quarter Ended			Quarter Ended			Quarter Ended			Quarter Ended
		March 31, 2014			June 30, 2014			September 30, 2014			December 31, 2014
	Net premiums earned	$	396,266		$	481,538		$	514,895		$	471,279
	Net investment income	40,990			39,302			25,357			25,894
	Net realized and unrealized gains (losses)	4,872			3,411			9,788			(3,788		)
	Net impairment losses recognized in earnings	(111		)	(198		)	(102		)	(214		)
	Subtotal	$	442,017		$	524,053		$	549,938		$	493,171
	Net losses and loss expenses	$	176,896		$	259,196		$	290,269		$	243,801
	Acquisition and general and administrative expenses	$	145,363		$	165,056		$	174,307		$	148,374
	Net foreign exchange losses (gains)	$	2,964		$	319		$	783		$	(227	)
	Net income	$	104,480		$	83,163		$	76,234		$	84,573
	Preferred dividends	(8,188		)	(8,188		)	(8,188		)	(8,186		)
	Net income available to common and participating common shareholders	$	96,292		$	74,975		$	68,046		$	76,387
	Basic earnings per share	$	2.16		$	1.68		$	1.52		$	1.71
	Diluted earnings per share	$	2.16		$	1.68		$	1.52		$	1.7
	The following is a summary of the unaudited quarterly data for the year ended December 31, 2013:
		Quarter Ended			Quarter Ended			Quarter Ended			Quarter Ended
		March 31, 2013			June 30, 2013			September 30, 2013			December 31, 2013
	Net premiums earned	$	420,117		$	543,335		$	553,545		$	499,487
	Net investment income	49,305			32,468			38,097			46,346
	Net realized and unrealized gains (losses)	6,235			10,372			(6,640		)	5,197
	Net impairment losses recognized in earnings	(806		)	(579		)	(190		)	(41		)
	Subtotal	$	474,851		$	585,596		$	584,812		$	550,989
	Net losses and loss expenses	$	218,970		$	359,058		$	339,036		$	302,620
	Acquisition and general and administrative expenses	$	138,114		$	153,227		$	146,245		$	161,750
	Net foreign exchange losses	$	2,927		$	3,368		$	2,201		$	5,718
	Net income	$	100,299		$	61,019		$	83,416		$	67,181
	Preferred dividends	(8,188		)	(8,188		)	(8,188		)	(8,186		)
	Net income available to common and participating common shareholders	$	92,111		$	52,831		$	75,228		$	58,995
	Basic earnings per share	$	2.13		$	1.21		$	1.7		$	1.33
	Diluted earnings per share	$	2.13		$	1.21		$	1.7		$	1.33

Summary_Of_Significant_Account2

Summary Of Significant Accounting Policies (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Significant Accounting Policies [Line Items]
Premiums Earned LO Duration	12 months
Premiums Earned Risk Attaching Duration	24 months
Allowance for estimated uncollectible premiums receivable	$2.60	$2.30
Cash equivalents maturity, in days	90 days
Vesting period for employee awards	4 years
Restricted share awards to non-employee directors, vesting period	1 year
High
Significant Accounting Policies [Line Items]
Short-term investments maturity, in days	1 year
Low
Significant Accounting Policies [Line Items]
Short-term investments maturity, in days	90 days

Investments_Narrative_Details

Investments (Narrative) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Investments [Abstract]
Number of available for sale securities in an unrealized loss position	747				880				747	880
Number of securities in a continuous unrealized loss position for twelve months or greater	171				71				171	71
Unrealized losses	($19,900,000)				($49,600,000)				($19,900,000)	($49,600,000)
Unrealized losses, 12 months or greater	-7,100,000				-5,800,000				-7,100,000	-5,800,000
OTTI losses recognized	$214,000	$102,000	$198,000	$111,000	$41,000	$190,000	$579,000	$806,000	$625,000	$1,616,000	$847,000

Investments_Composition_Of_Net

Investments (Composition Of Net Investment Income) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Investments [Abstract]
Available for sale investments									$123,773	$113,074	$135,841
Other investments									19,609	64,321	49,059
Cash and cash equivalents									2,445	2,752	1,616
Gross investment income									145,827	180,147	186,516
Investment expenses									-14,284	-13,931	-13,190
Net investment income	$25,894	$25,357	$39,302	$40,990	$46,346	$38,097	$32,468	$49,305	$131,543	$166,216	$173,326

Investments_Summary_Of_Investm

Investments (Summary Of Investment Portfolio By Investment Type) (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Summary of Investment Holdings [Line Items]
Fair Value	$6,607,084		$6,500,650
Percentage	100.00%		100.00%
Fixed maturity securities
Summary of Investment Holdings [Line Items]
Fair Value	5,092,581		4,823,964
Percentage	77.10%		74.20%
Cash and cash equivalents
Summary of Investment Holdings [Line Items]
Fair Value	632,667		771,714
Percentage	9.60%	[1]	11.90%	[1]
Other investments
Summary of Investment Holdings [Line Items]
Fair Value	541,454		617,478
Percentage	8.20%	[2]	9.50%	[2]
Short-term investments
Summary of Investment Holdings [Line Items]
Fair Value	9,014		35,028
Percentage	0.10%		0.50%
Equity securities
Summary of Investment Holdings [Line Items]
Fair Value	$331,368		$252,466
Percentage	5.00%		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 $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
U.S. government and agencies securities
Investments By Rating [Line Items]
Fair Value	$587,411	[1]	$769,343	[1]
Percentage	11.50%	[1]	15.80%	[1]
AAA/Aaa
Investments By Rating [Line Items]
Fair Value	1,206,252	[1]	972,820	[1]
Percentage	23.60%	[1]	20.00%	[1]
AA/Aa
Investments By Rating [Line Items]
Fair Value	1,717,343	[1]	1,771,156	[1]
Percentage	33.70%	[1]	36.50%	[1]
A/A
Investments By Rating [Line Items]
Fair Value	1,045,301	[1]	895,549	[1]
Percentage	20.50%	[1]	18.40%	[1]
BBB
Investments By Rating [Line Items]
Fair Value	427,018	[1]	363,722	[1]
Percentage	8.40%	[1]	7.50%	[1]
Below BBB
Investments By Rating [Line Items]
Fair Value	96,244	[1]	66,791	[1]
Percentage	1.90%	[1]	1.40%	[1]
Not rated
Investments By Rating [Line Items]
Fair Value	22,026	[1]	19,611	[1]
Percentage	0.40%	[1]	0.40%	[1]
Total fixed income investments
Investments By Rating [Line Items]
Fair Value	$5,101,595	[1]	$4,858,992	[1]
Percentage	100.00%	[1]	100.00%	[1]
[1]	The credit rating for each security reflected above was determined based on the rating assigned to the individual security by StandardB & Poorbs Financial Services LLC (bS&Pb). If a rating is not supplied by S&P, the equivalent rating supplied by Moodybs Investors Service, Inc. (bMoodybsb), Fitch Ratings, Inc., or DBRS, Inc. is used.

Investments_Contractual_Maturi

Investments (Contractual Maturities Of Fixed Income Securities) (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Due within one year, amortized cost	$126,921		$144,814
Due within one year, fair value	127,821		145,653
Due after one year through five years, amortized cost	1,627,154		1,808,001
Due after one year through five years, fair value	1,632,259		1,815,240
Due after five years through ten years, amortized cost	474,959		290,391
Due after five years through ten years, fair value	479,138		288,486
Due after ten years, amortized cost	43,314		26,344
Due after ten years, fair value	46,720		26,937
Fixed income investments, amortized cost	5,032,506		4,802,580
Fixed income investments, fair value	5,092,581		4,823,964
Residential mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
No single maturity date, amortized cost	1,149,536		1,192,085
No single maturity date, fair value	1,175,006		1,187,191
Fixed income investments, amortized cost	1,149,536		1,192,085
Fixed income investments, fair value	1,175,006		1,187,191
Commercial mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
No single maturity date, amortized cost	960,598		932,263
No single maturity date, fair value	979,419		947,677
Fixed income investments, amortized cost	960,598		932,263
Fixed income investments, fair value	979,419		947,677
Collateralized loan and debt obligations
Schedule of Available-for-sale Securities [Line Items]
No single maturity date, amortized cost	247,510		92,519
No single maturity date, fair value	248,011		94,552
Fixed income investments, amortized cost	247,510	[1]	92,519	[2]
Fixed income investments, fair value	248,011	[1]	94,552	[2]
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
No single maturity date, amortized cost	411,529		351,192
No single maturity date, fair value	413,221		353,256
Fixed income investments, amortized cost	411,529		351,192
Fixed income investments, fair value	413,221		353,256
Total fixed income investments
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	5,041,521		4,837,609
Fixed income investments, fair value	$5,101,595		$4,858,992
[1]	Balances include amounts related to collateralized debt obligations held with total fair values of $15.2 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 $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Equity Method Investments [Line Items]
Market Value	$541,454	$617,478
Unfunded Commitments	70,542	57,997
Ineligible for Redemption	85,244	107,109
Alternative Funds [Member]
Schedule of Equity Method Investments [Line Items]
Market Value	485,944	461,141
Unfunded Commitments	70,542	57,997
Ineligible for Redemption	85,244	107,109
Hedge funds
Schedule of Equity Method Investments [Line Items]
Market Value	411,280	401,438
Unfunded Commitments	0	0
Ineligible for Redemption	10,580	47,406
Private investment funds
Schedule of Equity Method Investments [Line Items]
Market Value	74,664	59,703
Unfunded Commitments	70,542	57,997
Ineligible for Redemption	74,664	59,703
Specialty Funds [Member]
Schedule of Equity Method Investments [Line Items]
Market Value	55,510	156,337
Unfunded Commitments	0	0
Ineligible for Redemption	0	0
High yield loan funds
Schedule of Equity Method Investments [Line Items]
Market Value	55,510	111,254
Unfunded Commitments	0	0
Ineligible for Redemption	0	0
Convertible debt funds
Schedule of Equity Method Investments [Line Items]
Market Value		45,083
Unfunded Commitments		0
Ineligible for Redemption		$0

Investments_Other_Investments_1

Investments (Other Investments Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Other investments, invested amount	$387,200,000	$440,900,000
Market Value	541,454,000	617,478,000
Alternative Funds [Member]
Schedule of Equity Method Investments [Line Items]
Market Value	485,944,000	461,141,000
Hedge funds
Schedule of Equity Method Investments [Line Items]
Market Value	411,280,000	401,438,000
Estimated liquidation, percentage in next 12 months	97.40%
Hedge funds | Low
Schedule of Equity Method Investments [Line Items]
Estimated notice period, in days	30 days
Hedge funds | High
Schedule of Equity Method Investments [Line Items]
Estimated notice period, in days	90 days
Private investment funds
Schedule of Equity Method Investments [Line Items]
Market Value	74,664,000	59,703,000
Private investment funds | Low
Schedule of Equity Method Investments [Line Items]
Estimated liquidation period, in years	5 years
Private investment funds | High
Schedule of Equity Method Investments [Line Items]
Estimated liquidation period, in years	10 years
Specialty Funds [Member]
Schedule of Equity Method Investments [Line Items]
Market Value	55,510,000	156,337,000
High yield loan funds
Schedule of Equity Method Investments [Line Items]
Market Value	55,510,000	111,254,000
High yield loan funds | Low
Schedule of Equity Method Investments [Line Items]
Estimated notice period, in days	30 days
High yield loan funds | High
Schedule of Equity Method Investments [Line Items]
Estimated notice period, in days	90 days
Convertible debt funds
Schedule of Equity Method Investments [Line Items]
Market Value		$45,083,000
Estimated notice period, in days	5 days

Investments_Net_Realized_And_U

Investments (Net Realized And Unrealized Gains) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Investments [Abstract]
Gross realized gains on investment sales									$35,921		$40,018		$77,474
Gross realized losses on investment sales									-16,515		-25,521		-6,164
Intangible asset impairment loss									-5,450	[1]	0	[1]	0	[1]
Change in fair value of derivative financial instruments(2)									327	[2]	667	[2]	829	[2]
Net realized and unrealized gains	($3,788)	$9,788	$3,411	$4,872	$5,197	($6,640)	$10,372	$6,235	$14,283		$15,164		$72,139
[1]	For additional information on the Company's intangible assets, see Note 10.
[2]	For additional information on the Companybs derivative financial instruments, see Note 8.

Investments_Amortized_Cost_Fai

Investments (Amortized Cost, Fair Value And Unrealized Gains And Losses And Other-Than-Temporary Impairments) (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	$5,032,506,000		$4,802,580,000
Fixed income investments, fair value	5,092,581,000		4,823,964,000
Equity securities, cost	303,922,000		227,828,000
Equity securities, fair value	331,368,000		252,466,000
Gross unrealized loss related to securities, non-credit OTTI	0		100,000
U.S. government and agencies securities
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	582,970,000		771,227,000
Fixed income investments, gross unrealized gains	6,471,000		5,735,000
Fixed income investments, gross unrealized losses	-2,030,000		-7,619,000
Fixed income investments, fair value	587,411,000		769,343,000
Non-credit OTTI	0	[1]	0	[2]
U.S. state and municipal securities
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	39,340,000		27,138,000
Fixed income investments, gross unrealized gains	191,000		111,000
Fixed income investments, gross unrealized losses	-118,000		-395,000
Fixed income investments, fair value	39,413,000		26,854,000
Non-credit OTTI	0	[1]	0	[2]
Foreign government securities
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	239,217,000		183,650,000
Fixed income investments, gross unrealized gains	2,983,000		1,003,000
Fixed income investments, gross unrealized losses	-1,664,000		-2,006,000
Fixed income investments, fair value	240,536,000		182,647,000
Non-credit OTTI	0	[1]	0	[2]
Government guaranteed corporate securities
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	47,436,000		34,921,000
Fixed income investments, gross unrealized gains	675,000		274,000
Fixed income investments, gross unrealized losses	-9,000		-50,000
Fixed income investments, fair value	48,102,000		35,145,000
Non-credit OTTI	0	[1]	0	[2]
Corporate securities
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	1,354,370,000		1,217,585,000
Fixed income investments, gross unrealized gains	12,742,000		16,225,000
Fixed income investments, gross unrealized losses	-5,650,000		-6,511,000
Fixed income investments, fair value	1,361,462,000		1,227,299,000
Non-credit OTTI	0	[1]	0	[2]
Residential mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	1,149,536,000		1,192,085,000
Fixed income investments, gross unrealized gains	27,542,000		17,005,000
Fixed income investments, gross unrealized losses	-2,072,000		-21,899,000
Fixed income investments, fair value	1,175,006,000		1,187,191,000
Non-credit OTTI	-3,233,000	[1]	-4,257,000	[2]
Commercial mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	960,598,000		932,263,000
Fixed income investments, gross unrealized gains	21,374,000		23,423,000
Fixed income investments, gross unrealized losses	-2,553,000		-8,009,000
Fixed income investments, fair value	979,419,000		947,677,000
Non-credit OTTI	-5,000	[1]	-47,000	[2]
Collateralized loan and debt obligations
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	247,510,000	[3]	92,519,000	[4]
Fixed income investments, gross unrealized gains	1,449,000	[3]	2,233,000	[4]
Fixed income investments, gross unrealized losses	-948,000	[3]	-200,000	[4]
Fixed income investments, fair value	248,011,000	[3]	94,552,000	[4]
Non-credit OTTI	0	[1],[3]	0	[2],[4]
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	411,529,000		351,192,000
Fixed income investments, gross unrealized gains	2,265,000		2,919,000
Fixed income investments, gross unrealized losses	-573,000		-855,000
Fixed income investments, fair value	413,221,000		353,256,000
Non-credit OTTI	0	[1]	-163,000	[2]
Total fixed maturity investments
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	5,032,506,000		4,802,580,000
Fixed income investments, gross unrealized gains	75,692,000		68,928,000
Fixed income investments, gross unrealized losses	-15,617,000		-47,544,000
Fixed income investments, fair value	5,092,581,000		4,823,964,000
Non-credit OTTI	-3,238,000	[1]	-4,467,000	[2]
Short-term investments
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	9,015,000		35,029,000
Fixed income investments, gross unrealized gains	0		1,000
Fixed income investments, gross unrealized losses	-1,000		-2,000
Fixed income investments, fair value	9,014,000		35,028,000
Non-credit OTTI	0	[1]	0	[2]
Total fixed income investments
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, amortized cost	5,041,521,000		4,837,609,000
Fixed income investments, gross unrealized gains	75,692,000		68,929,000
Fixed income investments, gross unrealized losses	-15,618,000		-47,546,000
Fixed income investments, fair value	5,101,595,000		4,858,992,000
Non-credit OTTI	-3,238,000	[1]	-4,467,000	[2]
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Equity securities, cost	303,922,000		227,828,000
Equity securities, gross unrealized gains	31,682,000		26,712,000
Equity securities, gross unrealized loss	-4,236,000		-2,074,000
Equity securities, fair value	331,368,000		252,466,000
Non-credit OTTI	0	[1]	0	[2]
Equity investments
Schedule of Available-for-sale Securities [Line Items]
Equity securities, cost	176,167,000		152,525,000
Equity securities, gross unrealized gains	29,660,000		24,139,000
Equity securities, gross unrealized loss	-3,292,000		-1,995,000
Equity securities, fair value	202,535,000		174,669,000
Non-credit OTTI	0	[1]	0	[2]
Emerging market debt funds
Schedule of Available-for-sale Securities [Line Items]
Equity securities, cost	60,826,000		60,250,000
Equity securities, gross unrealized gains	0		594,000
Equity securities, gross unrealized loss	-676,000		0
Equity securities, fair value	60,150,000		60,844,000
Non-credit OTTI	0	[1]	0	[2]
Convertible funds
Schedule of Available-for-sale Securities [Line Items]
Equity securities, cost	46,331,000
Equity securities, gross unrealized gains	0
Equity securities, gross unrealized loss	-220,000
Equity securities, fair value	46,111,000
Non-credit OTTI	0	[1]
Preferred equity investments
Schedule of Available-for-sale Securities [Line Items]
Equity securities, cost	13,858,000		6,325,000
Equity securities, gross unrealized gains	2,022,000		1,977,000
Equity securities, gross unrealized loss	-44,000		-79,000
Equity securities, fair value	15,836,000		8,223,000
Non-credit OTTI	0	[1]	0	[2]
Short-term fixed income fund
Schedule of Available-for-sale Securities [Line Items]
Equity securities, cost	6,740,000		8,728,000
Equity securities, gross unrealized gains	0		2,000
Equity securities, gross unrealized loss	-4,000		0
Equity securities, fair value	6,736,000		8,730,000
Non-credit OTTI	0	[1]	0	[2]
Collateralized Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed income investments, fair value	$15,200,000		$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 DecemberB 31, 2014, the gross unrealized loss related to fixed income investments for which a non-credit OTTI was recognized in accumulated other comprehensive income was nil.
[2]	Represents total OTTI recognized in accumulated other comprehensive income. It does not include the change in fair value subsequent to the impairment measurement date. At DecemberB 31, 2013, the gross unrealized loss related to fixed income investments for which a non-credit OTTI was recognized in accumulated other comprehensive income was $0.1 million.
[3]	Balances include amounts related to collateralized debt obligations held with total fair values of $15.2 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 $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, 12 months or greater	($7,100)		($5,800)
Unrealized losses	-19,900		-49,600
U.S. government and agencies securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-481	[1]	-7,359	[2]
Fair value, less than 12 months	155,350		382,593
Unrealized losses, 12 months or greater	-1,549	[1]	-260	[2]
Fair value, 12 months or greater	45,993		6,050
Unrealized losses	-2,030	[1]	-7,619	[2]
Fair value	201,343		388,643
U.S. state and municipal securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-47	[1]	-395	[2]
Fair value, less than 12 months	3,295		20,452
Unrealized losses, 12 months or greater	-71	[1]	0	[2]
Fair value, 12 months or greater	6,841		0
Unrealized losses	-118	[1]	-395	[2]
Fair value	10,136		20,452
Foreign government securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-1,378	[1]	-1,981	[2]
Fair value, less than 12 months	37,904		139,503
Unrealized losses, 12 months or greater	-286	[1]	-25	[2]
Fair value, 12 months or greater	4,306		5,261
Unrealized losses	-1,664	[1]	-2,006	[2]
Fair value	42,210		144,764
Government guaranteed corporate securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-9	[1]	-50	[2]
Fair value, less than 12 months	4,598		13,326
Unrealized losses, 12 months or greater	0	[1]	0	[2]
Fair value, 12 months or greater	0		0
Unrealized losses	-9	[1]	-50	[2]
Fair value	4,598		13,326
Corporate securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-4,023	[1]	-5,959	[2]
Fair value, less than 12 months	533,139		478,287
Unrealized losses, 12 months or greater	-1,627	[1]	-552	[2]
Fair value, 12 months or greater	84,278		28,690
Unrealized losses	-5,650	[1]	-6,511	[2]
Fair value	617,417		506,977
Residential mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-260	[1]	-17,542	[2]
Fair value, less than 12 months	62,832		514,702
Unrealized losses, 12 months or greater	-1,812	[1]	-4,357	[2]
Fair value, 12 months or greater	108,899		102,446
Unrealized losses	-2,072	[1]	-21,899	[2]
Fair value	171,731		617,148
Commercial mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-1,068	[1]	-7,681	[2]
Fair value, less than 12 months	180,222		384,548
Unrealized losses, 12 months or greater	-1,485	[1]	-328	[2]
Fair value, 12 months or greater	78,412		16,804
Unrealized losses	-2,553	[1]	-8,009	[2]
Fair value	258,634		401,352
Collateralized loan and debt obligations
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-876	[1]	-48	[2]
Fair value, less than 12 months	176,439		20,733
Unrealized losses, 12 months or greater	-72	[1]	-152	[2]
Fair value, 12 months or greater	6,491		2,379
Unrealized losses	-948	[1]	-200	[2]
Fair value	182,930		23,112
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-415	[1]	-703	[2]
Fair value, less than 12 months	199,205		157,172
Unrealized losses, 12 months or greater	-158	[1]	-152	[2]
Fair value, 12 months or greater	19,095		7,011
Unrealized losses	-573	[1]	-855	[2]
Fair value	218,300		164,183
Total fixed maturity investments
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-8,557	[1]	-41,718	[2]
Fair value, less than 12 months	1,352,984		2,111,316
Unrealized losses, 12 months or greater	-7,060	[1]	-5,826	[2]
Fair value, 12 months or greater	354,315		168,641
Unrealized losses	-15,617	[1]	-47,544	[2]
Fair value	1,707,299		2,279,957
Short-term investments
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-1	[1]	-2	[2]
Fair value, less than 12 months	1,953		2,468
Unrealized losses, 12 months or greater	0	[1]	0	[2]
Fair value, 12 months or greater	0		0
Unrealized losses	-1	[1]	-2	[2]
Fair value	1,953		2,468
Total fixed income investments
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-8,558	[1]	-41,720	[2]
Fair value, less than 12 months	1,354,937		2,113,784
Unrealized losses, 12 months or greater	-7,060	[1]	-5,826	[2]
Fair value, 12 months or greater	354,315		168,641
Unrealized losses	-15,618	[1]	-47,546	[2]
Fair value	1,709,252		2,282,425
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-4,236	[1]	-2,074	[2]
Fair value, less than 12 months	171,037		39,738
Unrealized losses, 12 months or greater	0	[1]	0	[2]
Fair value, 12 months or greater	0		0
Unrealized losses	-4,236	[1]	-2,074	[2]
Fair value	171,037		39,738
Equity investments
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-3,292	[1]	-1,995	[2]
Fair value, less than 12 months	53,591		36,751
Unrealized losses, 12 months or greater	0	[1]	0	[2]
Fair value, 12 months or greater	0		0
Unrealized losses	-3,292	[1]	-1,995	[2]
Fair value	53,591		36,751
Emerging market debt funds
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-676	[1]
Fair value, less than 12 months	60,150
Unrealized losses, 12 months or greater	0	[1]
Fair value, 12 months or greater	0
Unrealized losses	-676	[1]
Fair value	60,150
Convertible funds
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-220	[1]
Fair value, less than 12 months	46,111
Unrealized losses, 12 months or greater	0	[1]
Fair value, 12 months or greater	0
Unrealized losses	-220	[1]
Fair value	46,111
Preferred equity investments
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-44	[1]	-79	[2]
Fair value, less than 12 months	4,449		2,987
Unrealized losses, 12 months or greater	0	[1]	0	[2]
Fair value, 12 months or greater	0		0
Unrealized losses	-44	[1]	-79	[2]
Fair value	4,449		2,987
Short-term fixed income fund
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses, less than 12 months	-4	[1]
Fair value, less than 12 months	6,736
Unrealized losses, 12 months or greater	0	[1]
Fair value, 12 months or greater	0
Unrealized losses	-4	[1]
Fair value	$6,736
[1]	Gross unrealized losses include unrealized losses on non-OTTI and non-credit OTTI securities recognized in accumulated other comprehensive income at DecemberB 31, 2014.
[2]	Gross unrealized losses include unrealized losses on non-OTTI and non-credit OTTI securities recognized in accumulated other comprehensive income at DecemberB 31, 2013.

Investments_Analysis_Of_OTTI_D

Investments (Analysis Of OTTI) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities [Abstract]
Total other-than-temporary impairment losses									($625)	($1,616)	($364)
Portion of loss recognized in other comprehensive income (loss)									0	0	-483
Net impairment losses recognized in earnings	($214)	($102)	($198)	($111)	($41)	($190)	($579)	($806)	($625)	($1,616)	($847)

Investments_Credit_Losses_On_A

Investments (Credit Losses On Available-for-sale Securities Recognized In Earnings, OTTI Loss Was Recognized In Accumulated Other Comprehensive Income) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Beginning balance	($1,553)	($2,000)	($2,225)
Addition for the amount related to the credit loss for which an other-than-temporary impairment was not previously recognized	0	0	-3
Addition for the amount related to the credit loss for which an other-than-temporary impairment was previously recognized	0	0	-502
Reductions for increases in cash flows expected to be collected that are recognized over the remaining life of the security	0	0	0
Reductions for securities sold during the year	715	447	730
Ending balance	($838)	($1,553)	($2,000)

Fair_Value_Measurement_Narrati

Fair Value Measurement (Narrative) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Transfers into Level 3									$13,311,000	$11,729,000
Transfers out of Level 3									-7,497,000	-8,463,000
Net impairment losses recognized in earnings	214,000	102,000	198,000	111,000	41,000	190,000	579,000	806,000	625,000	1,616,000	847,000
Amount of transfers from Level 1 to Level 2	6,600,000								6,600,000
Significant Unobservable Inputs (Level 3)
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Percentage of level 3 assets	9.50%				10.90%				9.50%	10.90%
Net impairment losses recognized in earnings									$0

Fair_Value_Measurement_Schedul

Fair Value Measurement (Schedule Of Available For Sale Investments, Other Investments, Other Assets And Liabilities, and Debt Measured On A Recurring Basis) (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	$5,092,581		$4,823,964
Short-term investments	9,014		35,028
Total equity securities	331,368		252,466
Other investments	541,454		617,478
Other assets (see Note 8)	99,504		108,272
Total assets	6,073,921		5,837,208
Other liabilities (see Note 8)	54,338		49,452
Debt	623,740		575,115
Total liabilities	678,078		624,567
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0		0
Other investments	0		0
Other assets (see Note 8)	0		0
Total assets	250,320		146,754
Other liabilities (see Note 8)	0		0
Debt	0		0
Total liabilities	0		0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	9,014		35,028
Other investments	0		0
Other assets (see Note 8)	73,889		94,234
Total assets	5,244,242		5,051,610
Other liabilities (see Note 8)	18,972		29,883
Debt	623,740		575,115
Total liabilities	642,712		604,998
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	0		0
Other investments	541,454		617,478
Other assets (see Note 8)	25,615		14,038
Total assets	579,359		638,844
Other liabilities (see Note 8)	35,366		19,569
Debt	0		0
Total liabilities	35,366		19,569
U.S. government and agencies securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	587,411		769,343
U.S. government and agencies securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	105,121		20,248
U.S. government and agencies securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	482,290		749,095
U.S. government and agencies securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	0		0
U.S. state and municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	39,413		26,854
U.S. state and municipal securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	0		0
U.S. state and municipal securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	39,413		26,854
U.S. state and municipal securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	0		0
Foreign government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	240,536		182,647
Foreign government securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	0		0
Foreign government securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	240,536		182,647
Foreign government securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	0		0
Government guaranteed corporate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	48,102		35,145
Government guaranteed corporate securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	0		0
Government guaranteed corporate securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	48,102		35,145
Government guaranteed corporate securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	0		0
Corporate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	1,361,462		1,227,299
Corporate securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	0		0
Corporate securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	1,358,960		1,226,553
Corporate securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	2,502		746
Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	1,175,006		1,187,191
Residential mortgage-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	0		0
Residential mortgage-backed securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	1,174,997		1,186,943
Residential mortgage-backed securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	9		248
Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	979,419		947,677
Commercial mortgage-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	0		0
Commercial mortgage-backed securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	974,602		946,794
Commercial mortgage-backed securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	4,817		883
Collateralized loan and debt obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	248,011	[1]	94,552	[2]
Collateralized loan and debt obligations | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	0		0
Collateralized loan and debt obligations | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	246,042		92,095
Collateralized loan and debt obligations | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	1,969		2,457
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	413,221		353,256
Asset-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	0		0
Asset-backed securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	410,228		350,262
Asset-backed securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	2,993		2,994
Total fixed maturity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	5,092,581		4,823,964
Total fixed maturity investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	105,121		20,248
Total fixed maturity investments | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	4,975,170		4,796,388
Total fixed maturity investments | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fixed maturity investments	12,290		7,328
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	331,368		252,466
Equity securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	145,199		126,506
Equity securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	186,169		125,960
Equity securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	0		0
Equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	202,535		174,669
Equity investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	138,463		117,776
Equity investments | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	64,072		56,893
Equity investments | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	0		0
Emerging market debt funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	60,150		60,844
Emerging market debt funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	0		0
Emerging market debt funds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	60,150		60,844
Emerging market debt funds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	0		0
Convertible funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	46,111
Convertible funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	0
Convertible funds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	46,111
Convertible funds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	0
Preferred equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	15,836		8,223
Preferred equity investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	0		0
Preferred equity investments | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	15,836		8,223
Preferred equity investments | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	0		0
Short-term fixed income fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	6,736		8,730
Short-term fixed income fund | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	6,736		8,730
Short-term fixed income fund | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	0		0
Short-term fixed income fund | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	$0		$0
[1]	Balances include amounts related to collateralized debt obligations held with total fair values of $15.2 million.
[2]	Balances include amounts related to collateralized debt obligations held with total fair values of $18.7 million.

Fair_Value_Measurement_Quantit

Fair Value Measurement (Quantitative Information Used As Level 3 Inputs) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Net weather and energy related derivative liabilities	$45,166,000	$58,820,000
Derivatives recorded in other assets, fair value	99,504,000	108,272,000
Derivatives recorded in other liabilities, fair value	54,338,000	49,452,000
Significant Unobservable Inputs (Level 3)
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Derivatives recorded in other assets, fair value	25,615,000	14,038,000
Derivatives recorded in other liabilities, fair value	35,366,000	19,569,000
Energy Related Derivative [Member]
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Derivatives recorded in other assets, fair value	25,615,000	14,038,000
Derivatives recorded in other liabilities, fair value	35,366,000	19,569,000
Energy Related Derivative [Member] | Significant Unobservable Inputs (Level 3)
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Net weather and energy related derivative liabilities	9,751,000	5,531,000
Energy Related Derivative [Member] | Significant Unobservable Inputs (Level 3) | Valuation Techniques | High
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Correlation	1	1
Weather curve	2,500,000	7,940,000
Commodity curve	0	10
Energy Related Derivative [Member] | Significant Unobservable Inputs (Level 3) | Valuation Techniques | Low
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Correlation	0	0
Weather curve	-828,000	0
Commodity curve	$0	$0.65

Fair_Value_Measurement_Reconci

Fair Value Measurement (Reconciliation Of The Beginning And Ending Balances For All Available For Sale Investments Measured At Fair Value On A Recurring Basis Using Level 3) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Level 3, beginning of year	$638,844	$526,925
Total equity income and realized gains included in earnings	58,699	86,732
Total equity losses and losses included in earnings	-39,032	-22,301
Total income included in other underwriting loss	32,642	10,452
Total loss included in other underwriting loss	-27,147	-6,927
Change in unrealized gains included in other comprehensive income (loss)	801	749
Change in unrealized losses included in other comprehensive income (loss)	-706	-305
Purchases	62,672	72,230
Issues	15,631	6,637
Sales	-156,503	-38,614
Settlements	-12,356
Transfers into Level 3	13,311	11,729
Transfers out of Level 3	-7,497	-8,463
Level 3, end of year	579,359	638,844
Fixed maturity investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Level 3, beginning of year	7,328	8,497
Total equity income and realized gains included in earnings	144	127
Total equity losses and losses included in earnings	-85	-17
Total income included in other underwriting loss	0	0
Total loss included in other underwriting loss	0	0
Change in unrealized gains included in other comprehensive income (loss)	801	749
Change in unrealized losses included in other comprehensive income (loss)	-706	-305
Purchases	842	1,665
Issues	0	0
Sales	-1,848	-6,654
Settlements	0
Transfers into Level 3	13,311	11,729
Transfers out of Level 3	-7,497	-8,463
Level 3, end of year	12,290	7,328
Other investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Level 3, beginning of year	617,478	517,546
Total equity income and realized gains included in earnings	58,555	86,605
Total equity losses and losses included in earnings	-38,947	-22,284
Total income included in other underwriting loss	0	0
Total loss included in other underwriting loss	0	0
Change in unrealized gains included in other comprehensive income (loss)	0	0
Change in unrealized losses included in other comprehensive income (loss)	0	0
Purchases	59,023	67,571
Issues	0	0
Sales	-154,655	-31,960
Settlements	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Level 3, end of year	541,454	617,478
Other assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Level 3, beginning of year	14,038	882
Total equity income and realized gains included in earnings	0	0
Total equity losses and losses included in earnings	0	0
Total income included in other underwriting loss	32,642	10,452
Total loss included in other underwriting loss	-27,147	-6,927
Change in unrealized gains included in other comprehensive income (loss)	0	0
Change in unrealized losses included in other comprehensive income (loss)	0	0
Purchases	2,807	2,994
Issues	15,631	6,637
Sales	0	0
Settlements	-12,356
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Level 3, end of year	25,615	14,038
Other liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Level 3, beginning of year	-19,569	-1,922
Total equity income and realized gains included in earnings	0	0
Total equity losses and losses included in earnings	0	0
Total income included in other underwriting loss	29,040	7,340
Total loss included in other underwriting loss	-37,617	-11,126
Change in unrealized gains included in other comprehensive income (loss)	0	0
Change in unrealized losses included in other comprehensive income (loss)	0	0
Purchases	-1,404	-587
Issues	-25,692	-13,274
Sales	0	0
Settlements	19,876
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Level 3, end of year	($35,366)	($19,569)

Reserve_For_Losses_And_Loss_Ex3

Reserve For Losses And Loss Expenses (Narrative) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior year development	($233,815)	($222,392)	($120,157)
Reinsurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior year development	153,200	188,500	74,000
Insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior year development	$80,600	$33,900	$46,200

Reserve_For_Losses_And_Loss_Ex4

Reserve For Losses And Loss Expenses (Reserve For Losses And Loss Expenses) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Insurance Loss Reserves [Abstract]
Gross reserve for losses and loss expenses, January 1	$4,002,259	$4,240,876	$3,824,224
Reinsurance recoverable on unpaid losses	593,755	691,783	467,934
Net reserve for losses and loss expenses, January 1	3,408,504	3,549,093	3,356,290
Incurred related to Current year	1,203,977	1,442,076	1,641,152
Incurred related to Prior years	233,815	222,392	120,157
Total incurred	970,162	1,219,684	1,520,995
Paid related to Current year	-439,169	-524,010	-608,228
Paid related to Prior years	-719,043	-838,082	-715,528
Total paid	-1,158,212	-1,362,092	-1,323,756
Foreign currency translation and other	-44,390	1,819	-4,436
Net reserve for losses and loss expenses, December 31	3,176,064	3,408,504	3,549,093
Reinsurance recoverable on unpaid losses	670,795	593,755	691,783
Gross reserve for losses and loss expenses, December 31	$3,846,859	$4,002,259	$4,240,876

Reinsurance_Narrative_Details

Reinsurance (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reinsurance Disclosures [Abstract]
Ceded losses	$575.70	$683.20	$737.80

Reinsurance_Effects_Of_Reinsur

Reinsurance (Effects Of Reinsurance On Premiums Earned And Written) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reinsurance Disclosures [Abstract]
Direct premiums earned									$1,521,648	$1,472,796	$1,428,765
Assumed premiums earned									1,132,370	1,139,487	1,087,702
Ceded premiums earned									-790,040	-595,799	-502,567
Net premiums earned	471,279	514,895	481,538	396,266	499,487	553,545	543,335	420,117	1,863,978	2,016,484	2,013,900
Direct premiums written									1,716,128	1,475,429	1,429,930
Assumed premiums written									1,177,948	1,189,815	1,119,096
Ceded premiums written									-959,870	-616,311	-519,531
Net premiums written									$1,934,206	$2,048,933	$2,029,495

Reinsurance_Losses_Recoverable

Reinsurance (Losses Recoverable On Paid And Unpaid Losses By Rating) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Ceded Credit Risk [Line Items]
Reinsurance Recoverables	$889,086	$757,975
Collateralized [Member]
Ceded Credit Risk [Line Items]
Reinsurance Recoverables	199,700	14,200
U.S. government sponsored program
Ceded Credit Risk [Line Items]
Reinsurance Recoverables	339,617	356,049
A-plus and above
Ceded Credit Risk [Line Items]
Reinsurance Recoverables	294,216	253,665
A
Ceded Credit Risk [Line Items]
Reinsurance Recoverables	248,297	135,949
A- and below
Ceded Credit Risk [Line Items]
Reinsurance Recoverables	4	2,046
Not rated
Ceded Credit Risk [Line Items]
Reinsurance Recoverables	$6,952	$10,266

Debt_And_Financing_Arrangement1

Debt And Financing Arrangements (Details) (USD $)	0 Months Ended	12 Months Ended			0 Months Ended
	Apr. 19, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 02, 2014	8-May-07	Oct. 17, 2005	Jan. 17, 2014
Line of Credit Facility [Line Items]
Term of facility	4 years 0 months 0 days
Maximum borrowing capacity	$700,000,000					$1,175,000,000
Amount outstanding under credit facility		0	0				143,500,000
Amount of letters of credit outstanding		209,900,000	260,300,000
Increase to credit facility		350,000,000
Consolidated tangible net worth required		1,800,000,000
Aggregate interest payments		40,400,000	35,700,000	35,700,000
High
Line of Credit Facility [Line Items]
Leverage ratio		35.00%
Tranche 1 [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity		560,000,000
Line of credit facility collateralized LOC fee		0.45%
Tranche 2 [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity		140,000,000
Interest rate spread on federal funds rate		0.50%
Tranche 2 [Member] | Low
Line of Credit Facility [Line Items]
Line of credit facility uncollateralized LOC fee		1.13%
Tranche 2 [Member] | High
Line of Credit Facility [Line Items]
Line of credit facility uncollateralized LOC fee		1.75%
Tranche 2 [Member] | Eurodollar [Member]
Line of Credit Facility [Line Items]
Increase in interest rate on revolving loans		1.00%
Tranche 2 [Member] | Eurodollar [Member] | Low
Line of Credit Facility [Line Items]
Increase in interest rate on revolving loans		0.13%
Tranche 2 [Member] | Eurodollar [Member] | High
Line of Credit Facility [Line Items]
Increase in interest rate on revolving loans		0.75%
Tranche 2 [Member] | LIBOR [Member] | Low
Line of Credit Facility [Line Items]
Increase in interest rate on revolving loans		1.13%
Tranche 2 [Member] | LIBOR [Member] | High
Line of Credit Facility [Line Items]
Increase in interest rate on revolving loans		1.75%
Bridge Facility [Member]
Line of Credit Facility [Line Items]
Term of facility					364 days
Maximum borrowing capacity		1,000,000,000
Aggregate interest payments		4,800,000
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity								50,000,000
Amount of letters of credit outstanding		5,900,000	0
Credit Facility [Member]
Line of Credit Facility [Line Items]
Amount of letters of credit outstanding		204,000,000	260,300,000
Canadian LOC Agreement [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity		30,000,000
Amount of letters of credit outstanding		$0

Debt_And_Financing_Arrangement2

Debt And Financing Arrangements (Senior Notes) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Oct. 17, 2005	Mar. 23, 2010	Jul. 15, 2004
Debt Instrument [Line Items]
Aggregate interest payments	$40,400,000	$35,700,000	$35,700,000
Amount outstanding under credit facility	0	0		143,500,000
Seven Percent Senior Notes [Member]
Debt Instrument [Line Items]
Senior Notes, principal amount	335,000,000				85,000,000	250,000,000
Senior Notes, stated interest rate						7.00%
Senior Notes, price at issuance						94.98%
Senior Notes, effective yield						7.45%
Six Point One Five Percent Senior Notes [Member]
Debt Instrument [Line Items]
Senior Notes, principal amount				$200,000,000
Senior Notes, stated interest rate				6.15%
Senior Notes, price at issuance				99.64%
Senior Notes, effective yield				6.20%

Derivatives_Narrative_Details

Derivatives (Narrative) (Details) (Cash Flow Hedging [Member], USD $)	12 Months Ended
	Dec. 31, 2004
Cash Flow Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Rate of senior notes	7.00%
Notional amount	$125,000,000
Percentage of protection	50.00%
U.S. Treasury benchmark in years	30 years
Payment for interest rate lock derivative	$2,700,000

Derivatives_Schedule_Of_The_Fa

Derivatives (Schedule Of The Fair Values And The Related Notional Values Of Derivatives Included In The Company's Consolidated Balance Sheet) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Derivatives recorded in other assets, fair value	99,504,000	$108,272,000
Derivatives recorded in other liabilities, fair value	54,338,000	49,452,000
Net derivative asset	45,166,000	58,820,000
Derivative assets traded under master netting agreements	99,500,000	14,500,000
Derivative liabilities traded under master netting agreements	54,300,000	21,200,000
High
Derivatives, Fair Value [Line Items]
Original term of credit default swap, in years	5 years
Foreign exchange forward contracts
Derivatives, Fair Value [Line Items]
Derivatives recorded in other assets, fair value	651,000	251,000
Derivatives recorded in other liabilities, fair value	123,000	172,000
Derivative recorded in other assets, notional principal amount	42,694,000	19,269,000
Derivative recorded in other liabilities, notional principal amount	20,945,000	15,861,000
Interest rate swaps
Derivatives, Fair Value [Line Items]
Derivatives recorded in other assets, fair value	0	124,000
Derivatives recorded in other liabilities, fair value	20,000	933,000
Derivative recorded in other assets, notional principal amount	0	16,100,000
Derivative recorded in other liabilities, notional principal amount	12,549,000	12,193,000
Interest rate swaptions
Derivatives, Fair Value [Line Items]
Derivatives recorded in other assets, fair value	0	39,000
Derivatives recorded in other liabilities, fair value	9,000	543,000
Derivative recorded in other assets, notional principal amount	0	24,338,000
Derivative recorded in other liabilities, notional principal amount	13,100,000	361,455,000
Interest rate futures
Derivatives, Fair Value [Line Items]
Derivatives recorded in other assets, fair value	7,000	0
Derivatives recorded in other liabilities, fair value	0	17,000
Derivative recorded in other assets, notional principal amount	7,595,000	0
Derivative recorded in other liabilities, notional principal amount	0	103,935,000
TBAs
Derivatives, Fair Value [Line Items]
Derivatives recorded in other assets, fair value	73,231,000	93,820,000
Derivatives recorded in other liabilities, fair value	18,820,000	28,218,000
Derivative recorded in other assets, notional principal amount	70,000,000	93,840,000
Derivative recorded in other liabilities, notional principal amount	18,000,000	28,000,000
Energy and weather contracts
Derivatives, Fair Value [Line Items]
Derivatives recorded in other assets, fair value	25,615,000	14,038,000
Derivatives recorded in other liabilities, fair value	35,366,000	19,569,000
Derivative recorded in other assets, notional principal amount	81,624,000	53,986,000
Derivative recorded in other liabilities, notional principal amount	135,050,000	$66,113,000

Derivatives_Schedule_Of_The_Ga

Derivatives (Schedule Of The Gains And Losses On Derivative Instruments) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Total included in net realized and unrealized gains	$327	$667	$829
Total included in other underwriting loss	-315	-261	-2,684
Total gains from derivatives	1,892	763	-1,757
Foreign exchange forward contracts
Derivative [Line Items]
Total included in net foreign exchange losses (gains) from foreign exchange forward contracts	1,880	357	98
Interest rate futures
Derivative [Line Items]
Total included in net realized and unrealized gains	121	44	87
Credit default swaps
Derivative [Line Items]
Total included in net realized and unrealized gains	30	49	48
Interest rate swaps
Derivative [Line Items]
Total included in net realized and unrealized gains	-4,239	1,241	85
Interest rate swaptions
Derivative [Line Items]
Total included in net realized and unrealized gains	477	291	29
TBAs
Derivative [Line Items]
Total included in net realized and unrealized gains	3,938	-958	580
Energy and weather contracts
Derivative [Line Items]
Total included in other underwriting loss	-315	-261	0
Commodity put options
Derivative [Line Items]
Total included in other underwriting loss	$0	$0	($2,684)

Segment_Reporting_Summary_Of_T

Segment Reporting (Summary Of The Segment Revenues, Results And Reserve For Losses And Loss Expenses And Carrying Value Of Goodwill) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Gross premiums written									$2,894,076	$2,665,244	$2,549,026
Ceded premiums written									-959,870	-616,311	-519,531
Net premiums written									1,934,206	2,048,933	2,029,495
Net premiums earned	471,279	514,895	481,538	396,266	499,487	553,545	543,335	420,117	1,863,978	2,016,484	2,013,900
Other underwriting loss									-5,786	-2,046	-2,183
Total revenue									1,858,192	2,014,438	2,011,717
Net losses and loss expenses	243,801	290,269	259,196	176,896	302,620	339,036	359,058	218,970	970,162	1,219,684	1,520,995
Acquisition expenses									319,513	304,430	303,179
General and administrative expenses									313,587	294,906	235,689
Total expenses									1,603,262	1,819,020	2,059,863
Underwriting (loss) income									254,930	195,418	-48,146
Net loss ratio									52.10%	60.50%	75.50%
Acquisition expense ratio									17.10%	15.10%	15.10%
General and administrative expense ratio									16.80%	14.60%	11.70%
Combined ratio									86.00%	90.20%	102.30%
Reserve for losses and loss expenses	3,846,859				4,002,259				3,846,859	4,002,259	4,240,876	3,824,224
Goodwill	91,238				91,293				91,238	91,293	90,939
Insurance
Segment Reporting Information [Line Items]
Gross premiums written									1,716,128	1,475,429	1,429,930
Ceded premiums written									-855,722	-542,919	-487,573
Net premiums written									860,406	932,510	942,357
Net premiums earned									833,912	946,474	955,089
Other underwriting loss									0	0	-2,684
Total revenue									833,912	946,474	952,405
Net losses and loss expenses									594,561	774,425	855,941
Acquisition expenses									65,368	64,778	75,597
General and administrative expenses									174,575	157,596	125,108
Total expenses									834,504	996,799	1,056,646
Underwriting (loss) income									-592	-50,325	-104,241
Net loss ratio									71.40%	81.80%	89.60%
Acquisition expense ratio									7.80%	6.80%	7.90%
General and administrative expense ratio									20.90%	16.70%	13.10%
Combined ratio									100.10%	105.30%	110.60%
Reserve for losses and loss expenses	2,123,772				2,158,890				2,123,772	2,158,890	2,287,052
Goodwill	47,925				47,925				47,925	47,925	47,925
Reinsurance
Segment Reporting Information [Line Items]
Gross premiums written									1,177,948	1,189,815	1,119,096
Ceded premiums written									-104,148	-73,392	-31,958
Net premiums written									1,073,800	1,116,423	1,087,138
Net premiums earned									1,030,066	1,070,010	1,058,811
Other underwriting loss									-5,786	-2,046	501
Total revenue									1,024,280	1,067,964	1,059,312
Net losses and loss expenses									375,601	445,259	665,054
Acquisition expenses									254,145	239,652	227,582
General and administrative expenses									139,012	137,310	110,581
Total expenses									768,758	822,221	1,003,217
Underwriting (loss) income									255,522	245,743	56,095
Net loss ratio									36.40%	41.60%	62.80%
Acquisition expense ratio									24.70%	22.40%	21.50%
General and administrative expense ratio									13.50%	12.80%	10.40%
Combined ratio									74.60%	76.80%	94.70%
Reserve for losses and loss expenses	1,723,087				1,843,369				1,723,087	1,843,369	1,953,824
Goodwill	$43,313				$43,368				$43,313	$43,368	$43,014

Segment_Reporting_Schedule_Of_

Segment Reporting (Schedule Of Segment Results To Income Before Income Taxes) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting [Abstract]
Total underwriting income (loss)									$254,930	$195,418	($48,146)
Net investment income	25,894	25,357	39,302	40,990	46,346	38,097	32,468	49,305	131,543	166,216	173,326
Net foreign exchange (losses) gains	227	-783	-319	-2,964	-5,718	-2,201	-3,368	-2,927	-3,839	-14,214	15,911
Net realized and unrealized gains	-3,788	9,788	3,411	4,872	5,197	-6,640	10,372	6,235	14,283	15,164	72,139
Net impairment losses recognized in earnings	-214	-102	-198	-111	-41	-190	-579	-806	-625	-1,616	-847
Amortization of intangibles									-6,484	-7,012	-10,347
Interest expense									-40,968	-36,188	-36,174
Income before income taxes									$348,840	$317,768	$165,862

Segment_Reporting_Schedule_Of_1

Segment Reporting (Schedule Of Gross Premiums Written By Line Of Business) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue, Major Customer [Line Items]
Gross premiums written	$2,894,076	$2,665,244	$2,549,026
Insurance
Revenue, Major Customer [Line Items]
Gross premiums written	1,716,128	1,475,429	1,429,930
Agriculture
Revenue, Major Customer [Line Items]
Gross premiums written	866,025	954,389	903,730
Casualty and other specialty
Revenue, Major Customer [Line Items]
Gross premiums written	396,113	303,803	296,325
Professional lines
Revenue, Major Customer [Line Items]
Gross premiums written	263,538	148,537	169,815
Property, marine and energy
Revenue, Major Customer [Line Items]
Gross premiums written	190,452	68,700	60,060
Reinsurance
Revenue, Major Customer [Line Items]
Gross premiums written	1,177,948	1,189,815	1,119,096
Catastrophe
Revenue, Major Customer [Line Items]
Gross premiums written	343,213	355,751	378,387
Property
Revenue, Major Customer [Line Items]
Gross premiums written	287,326	297,806	349,579
Casualty
Revenue, Major Customer [Line Items]
Gross premiums written	159,533	241,358	208,353
Professional lines
Revenue, Major Customer [Line Items]
Gross premiums written	174,656	163,594	59,076
Specialty
Revenue, Major Customer [Line Items]
Gross premiums written	$213,220	$131,306	$123,701

Segment_Reporting_Schedule_Of_2

Segment Reporting (Schedule Of Geographic Distribution Of Gross Premiums Written) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Geographic Distribution Of Gross Premiums Category [Line Items]
Gross premiums written	$2,894,076	$2,665,244	$2,549,026
United States
Geographic Distribution Of Gross Premiums Category [Line Items]
Gross premiums written	2,054,431	1,960,693	1,901,686
Worldwide
Geographic Distribution Of Gross Premiums Category [Line Items]
Gross premiums written	456,078	435,655	412,941
Europe
Geographic Distribution Of Gross Premiums Category [Line Items]
Gross premiums written	172,077	153,516	121,363
Australasia
Geographic Distribution Of Gross Premiums Category [Line Items]
Gross premiums written	61,994	25,191	22,497
Japan
Geographic Distribution Of Gross Premiums Category [Line Items]
Gross premiums written	45,618	33,879	36,392
Canada
Geographic Distribution Of Gross Premiums Category [Line Items]
Gross premiums written	19,622	15,403	17,248
Other
Geographic Distribution Of Gross Premiums Category [Line Items]
Gross premiums written	$84,256	$40,907	$36,899

Goodwill_And_Intangible_Assets2

Goodwill And Intangible Assets (Narrative) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible asset impairment loss	($5,450)	[1]	$0	[1]	$0	[1]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization of intangible assets with finite lives, 2015	6,300
Amortization of intangible assets with finite lives, 2016	6,300
Amortization of intangible assets with finite lives, 2017	6,300
Amortization of intangible assets with finite lives, 2018	6,200
Amortization of intangible assets with finite lives, 2019	6,200
Amortization of intangible assets with finite lives, after 2019	$19,100
[1]	For additional information on the Company's intangible assets, see Note 10.

Goodwill_And_Intangible_Assets3

Goodwill And Intangible Assets (Schedule Of Goodwill And Intangible Assets) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Schedule Of Goodwill And Intangible Assets [Line Items]
Net beginning balance	$165,378		$172,000
Additions	-39		390
Amortization	-6,484		-7,012		-10,347
Intangible asset impairment loss	-5,450	[1]	0	[1]	0	[1]
Gross balance	246,509
Accumulated amortization	-87,654
Accumulated impairment losses	-5,450
Net balance	153,405		165,378		172,000
Goodwill
Schedule Of Goodwill And Intangible Assets [Line Items]
Net beginning balance	91,293		90,939
Additions	-55		354
Amortization	0		0
Goodwill impairment loss	0
Gross balance	91,238
Accumulated amortization	0
Goodwill accumulated impairment loss	0
Net balance	91,238		91,293
Intangible assets with indefinite lives
Schedule Of Goodwill And Intangible Assets [Line Items]
Net beginning balance	17,229		17,229
Additions	0		0
Amortization	0		0
Intangible asset impairment loss	-5,450		0
Intangible assets with indefinite lives, Gross balance	17,229
Accumulated amortization	0
Accumulated impairment losses	-5,450
Net balance	11,779		17,229
Intangible assets with finite lives
Schedule Of Goodwill And Intangible Assets [Line Items]
Net beginning balance	56,856		63,832
Additions	16		36
Amortization	-6,484		-7,012
Finite-lived intangible assets, impairment loss	0
Intangible assets with finite lives, Gross balance	138,042
Accumulated amortization	-87,654
Intangible assets with finite lives, accumulated impairment losses	0
Net balance	$50,388		$56,856
[1]	For additional information on the Company's intangible assets, see Note 10.

Commitments_And_Contingencies_1

Commitments And Contingencies (Narrative) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Securities pledged as collateral obligation	$130,600,000	$146,100,000
Cash and investments pledged under letters of credit facility	240,000,000	302,700,000
Number of custodians	3
Ceded Credit Risk [Line Items]
Reinsurance Recoverables	889,086,000	757,975,000
Collateralized [Member]
Ceded Credit Risk [Line Items]
Reinsurance Recoverables	199,700,000	14,200,000
U.S. Government Sponsored Reinsurance Program [Member]
Ceded Credit Risk [Line Items]
Reinsurance Recoverables	339,600,000	356,000,000
A- or better by A.M. Best or Standard And Poors [Member]
Ceded Credit Risk [Line Items]
Reinsurance Recoverables	$542,500,000	$391,700,000

Commitments_And_Contingencies_2

Commitments And Contingencies (Schedule Of Percentage Of Net Premiums Written) (Details) (Sales [Member])	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue, Major Customer [Line Items]
Percentage of net premium written	50.20%	49.10%	50.10%
Marsh & McLennan Companies, Inc.
Revenue, Major Customer [Line Items]
Percentage of net premium written	21.90%	19.50%	16.90%
Aon Benfield
Revenue, Major Customer [Line Items]
Percentage of net premium written	15.10%	17.70%	17.40%
Willis Companies
Revenue, Major Customer [Line Items]
Percentage of net premium written	13.20%	11.90%	15.80%

Commitments_And_Contingencies_3

Commitments And Contingencies Commitments And Contingencies (LOC) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Line of Credit Facility [Line Items]
Amount of letters of credit outstanding	$209.90	$260.30
Credit Facility [Member]
Line of Credit Facility [Line Items]
Amount of letters of credit outstanding	204	260.3
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Amount of letters of credit outstanding	$5.90	$0

Commitments_And_Contingencies_4

Commitments And Contingencies (Deposits) (Details) (United States, USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
United States
Statutory Accounting Practices [Line Items]
Assets Held by Insurance Regulators	$205.20	$273.70

Commitments_And_Contingencies_5

Commitments And Contingencies (Schedule Of Future Minimum Lease Commitments) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Commitments and Contingencies Disclosure [Abstract]
2015	$15,923,000
2016	12,779,000
2017	11,976,000
2018	10,936,000
2019	11,386,000
2020 and thereafter	33,783,000
Total	96,783,000
Total lease expense under operating leases	14,700,000	14,700,000	15,200,000
Total sublease income under operating leases	$1,300,000	$800,000	$300,000

Shareholders_Equity_Narrative_

Shareholders' Equity (Narrative) (Details) (USD $)	12 Months Ended		0 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Oct. 10, 2005	Jun. 01, 2011	Feb. 27, 2014
Class of Stock [Line Items]
Number of restricted shares issued	1,290,894
Shares authorized to be repurchased					5,000,000
Shares repurchased	0	318,252
Repurchase price, average cost per share		$45.83
Total authorized repurchases remaining shares	5,000,000	0
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Issued	8,000,000	8,000,000	8,000,000
Preferred stock, dividend percentage			7.75%
Preferred stock price at issue			$25
Net proceeds on issuance of preferred shares			$193.50
Preferred stock redemption price per share			$25
Preferred stock redemption price per share before stated redemption date			$26
Preferred stock, liquidation price per share			$25
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Issued	9,200,000	9,200,000		9,200,000
Preferred stock, dividend percentage				7.50%
Preferred stock price at issue				$25
Net proceeds on issuance of preferred shares				$224
Preferred stock redemption price per share				$25
Preferred stock redemption price per share before stated redemption date				$26
Preferred stock, liquidation price per share				$25

Shareholders_Equity_Schedule_O

Shareholders' Equity (Schedule Of Company's Share Capital) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Capital Unit [Line Items]
Preferred Stock, Shares Authorized	17,200,000	17,200,000
Common Stock, Shares Authorized	120,000,000	120,000,000
Common shares, ordinary, number of shares issued	44,765,153	44,368,742
Common Stock, Shares, Outstanding	44,765,153	44,368,742
Preferred Stock, Par or Stated Value Per Share	$1
Common Stock, Par or Stated Value Per Share	$1
Preferred shares, Series A and B, total liquidation preference	$430,000	$430,000
Series A Preferred Stock [Member]
Capital Unit [Line Items]
Preferred Stock, Shares Issued	8,000,000	8,000,000
Preferred Stock, Shares Outstanding	8,000,000	8,000,000
Preferred Stock, Par or Stated Value Per Share	$1
Preferred shares, Series A and B, total liquidation preference	200,000	200,000
Series B Preferred Stock [Member]
Capital Unit [Line Items]
Preferred Stock, Shares Issued	9,200,000	9,200,000
Preferred Stock, Shares Outstanding	9,200,000	9,200,000
Preferred Stock, Par or Stated Value Per Share	$1
Preferred shares, Series A and B, total liquidation preference	$230,000	$230,000

Shareholders_Equity_Schedule_O1

Shareholders' Equity (Schedule Of Changes In Accumulated Other Comprehensive Income By Component) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Accumulated Other Comprehensive Income [Line Items]
Beginning balance	$62,731		$152,463
Other comprehensive income (loss) before reclassifications	34,368		-77,991
Amounts reclassified from accumulated other comprehensive income	-20,393	[1]	-11,741	[1]
Net current period other comprehensive income (loss)	13,975		-89,732		22,071
Ending balance	76,706		62,731		152,463
Losses on cash flow hedges
Accumulated Other Comprehensive Income [Line Items]
Beginning balance	-1,855		-1,944
Other comprehensive income (loss) before reclassifications	0		0
Amounts reclassified from accumulated other comprehensive income	89	[1]	89	[1]
Net current period other comprehensive income (loss)	89		89
Ending balance	-1,766		-1,855
Unrealized gains (losses) on available for sale securities
Accumulated Other Comprehensive Income [Line Items]
Beginning balance	45,950		141,731
Other comprehensive income (loss) before reclassifications	60,632		-83,951
Amounts reclassified from accumulated other comprehensive income	-20,482	[1]	-11,830	[1]
Net current period other comprehensive income (loss)	40,150		-95,781
Ending balance	86,100		45,950
Foreign currency translation adjustments
Accumulated Other Comprehensive Income [Line Items]
Beginning balance	18,636		12,676
Other comprehensive income (loss) before reclassifications	-26,264		5,960
Amounts reclassified from accumulated other comprehensive income	0	[1]	0	[1]
Net current period other comprehensive income (loss)	-26,264		5,960
Ending balance	($7,628)		$18,636
[1]	All amounts are net of tax.

Shareholders_Equity_Schedule_O2

Shareholders' Equity (Schedule Of Reclassifications Out Of Accumulated Other Comprehensive Income) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense									$40,968	$36,188	$36,174
Net realized and unrealized gains	3,788	-9,788	-3,411	-4,872	-5,197	6,640	-10,372	-6,235	-14,283	-15,164	-72,139
Net impairment losses recognized in earnings	214	102	198	111	41	190	579	806	625	1,616	847
Income before income taxes									-348,840	-317,768	-165,862
Income tax expense									-390	-5,853	-3,346
Total net of income taxes	-84,573	-76,234	-83,163	-104,480	-67,181	-83,416	-61,019	-100,299	-348,450	-311,915	-162,516
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Member] | Losses on cash flow hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense									89	89
Income before income taxes									89	89
Income tax expense									0	0
Total net of income taxes									89	89
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Member] | Unrealized (gains) losses on available for sale securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized and unrealized gains									-19,406	-14,497
Net impairment losses recognized in earnings									625	1,616
Income before income taxes									-18,781	-12,881
Income tax expense									1,701	-1,051
Total net of income taxes									($20,482)	($11,830)

Earnings_Per_Share_Schedule_Of

Earnings Per Share (Schedule Of Computation Of Basic And Diluted Earnings Per Share) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Net income available to common and participating common shareholders	$76,387	$68,046	$74,975	$96,292	$58,995	$75,228	$52,831	$92,111	$315,700		$279,165		$129,766
Less amount allocated to participating common shareholders									-9,118	[1]	-6,444	[1]	-2,113	[1]
Net income allocated to common shareholders									$306,582		$272,721		$127,653
Weighted average shares - basic									43,368,062		42,817,624		42,567,736
Weighted average shares - diluted									43,415,243		42,818,207		42,601,835
Basic earnings per common share	$1.71	$1.52	$1.68	$2.16	$1.33	$1.70	$1.21	$2.13	$7.07		$6.37		$3
Diluted earnings per common share	$1.70	$1.52	$1.68	$2.16	$1.33	$1.70	$1.21	$2.13	$7.06		$6.37		$3
Restricted Stock [Member]
Share equivalents:									70		583		2,266
Employee Stock Option [Member]
Share equivalents:									47,111		0		31,833
[1]	Represents earnings and dividends attributable to holders of unvested restricted shares issued under the Companybs stock compensation plans 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 $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Dividends Declared [Line Items]
Dividends declared per common share	$1.36	$1.28	$1.24
Series A Preferred Stock [Member]
Dividends Declared [Line Items]
Dividends declared per preferred share	$1.94	$1.94	$1.94
Series B Preferred Stock [Member]
Dividends Declared [Line Items]
Dividends declared per preferred share	$1.88	$1.88	$1.88

Related_Party_Transactions_Det

Related Party Transactions (Details) (USD $)	12 Months Ended
Share data in Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Investment expenses	$14,284,000	$13,931,000	$13,190,000
Pyramis Global Advisors [Member]
Related Party Transaction [Line Items]
Investment expenses	1,400,000	1,400,000	1,400,000
Accrued investment expenses	$300,000	$400,000
Percentage of ordinary shares owned by related parties	8.10%
Ordinary shares owned by related parties	3.6

StockBased_Employee_Compensati3

Stock-Based Employee Compensation And Other Stock Plans (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	11-May-11	Feb. 23, 2011	Oct. 26, 2005
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options granted	0	800,000	0
Number of options expired	0	0	0
Number of options vested	160,000	160,000	0
Number of options exercised	15,000
Total intrinsic value of options exercised	$300,000	$500,000	$1,400,000
Proceeds from stock options exercised	500,000
Unrecognized stock based compensation expenses related to unvested stock options	2,600,000
Vesting period for employee awards	4 years
Restricted share awards to non-employee directors, vesting period	1 year
Number of restricted shares granted	505,997	503,097	437,284
Restricted shares weighted average grant date, aggregate fair value	26,700,000	58,100,000	16,800,000
Options weighted average grant date fair value		10,200,000
Aggregate fair value of restricted shares and RSUs vested	18,700,000	17,100,000	11,700,000
Compensation costs not yet recognized related to unvested restricted shares and restricted share units	23,300,000	29,700,000
Employee Share Purchase Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period shares are restricted from sale, transfer, or certification	1 year
Shares reserved for issuance under ESPP				400,000	200,000	200,000
Percentage of employee share purchase plans discount closing market price	15.00%
Expenses related to employee stock purchase plan	234,000	167,000	165,000
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options vesting rate	20.00%
Contractual life of stock options	10 years
Vesting period for employee awards	5 years
Compensation costs recognized	3,100,000	4,500,000	0
Percentage of compensation expense to be expensed next year	61.60%
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for employee awards	4 years
Compensation costs recognized	$27,900,000	$23,500,000	$11,200,000
Percentage of compensation expense to be expensed next year	62.40%
Dividend Restricted Stock Units RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for employee awards	6 months

StockBased_Employee_Compensati4

Stock-Based Employee Compensation And Other Stock Plans (Narrative 2) (Details) (USD $)	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 11, 2010	28-May-13	13-May-10	Feb. 28, 2007
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Ordinary shares available for issuance under 2007 Plan	1,738,370	2,107,889
Number of options granted	0
Weighted average Exercise Price, Granted	$0
Number of restricted shares granted	505,997	503,097	437,284
Vesting period for employee awards	4 years
Stock Based Employee Compensation Plans Two Thousand Seven Plan [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Addition ordinary shares				1,795,000
Ordinary shares available for issuance under 2007 Plan						3,895,000	2,100,000
Chief Executive Officer [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of options granted					800,000
Weighted average Exercise Price, Granted					$48.20
Number of restricted shares granted					708,890
Contractual life of stock options					10 years
Employee Stock Option [Member] | Chief Executive Officer [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of tranches					5
Restricted Stock [Member] | Chief Executive Officer [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of tranches					5

StockBased_Employee_Compensati5

Stock-Based Employee Compensation And Other Stock Plans (Summary Of Stock Option Activity) (Details) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted average remaining contractual life in years, options outstanding, end of year	8 years 4 months 27 days
Number of options granted	0	800,000	0
Weighted Average Remaining Contractual Life (years), Exercisable and vested options, end of year	8 years 4 months 27 days
Aggregate Intrinsic Value, Outstanding, end of year	$9,312
Aggregate Intrinsic Value, Exercisable and vested options, end of year	$3,725
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of options, beginning of year	815,000
Number of options granted	0
Number of options exercised	-15,000
Number of options forfeited	0
Number of options outstanding, end of year	800,000	815,000
Number of options exercisable and vested, end of year	320,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Beginning of year	$47.94
Weighted average Exercise Price, Granted	$0
Weighted Average Exercise Price, Exercised	$33.91
Weighted Average Exercise Price, Forfeited	$0
Weighted Average Exercise Price, Outstanding, end of year	$48.20	$47.94
Weighted Average Exercise Price, Exercisable and vested options, end of year	$48.20

StockBased_Employee_Compensati6

Stock-Based Employee Compensation And Other Stock Plans (Restricted Share And Restricted Share Unit Activity) (Details) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested, beginning of year	1,261,260
Granted	505,997	503,097	437,284
Settled	-402,479
Forfeited	-73,884
Unvested, end of year	1,290,894	1,261,260
Number of Shares/Units, Outstanding, end of year	1,290,894	1,261,260
Aggregate Intrinsic Value, Outstanding, end of year	$77,247

Pension_Plan_Details

Pension Plan (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Contribution Plan Disclosure [Line Items]
Expenses related to contributions	$12.60	$10.80	$7.40
Low
Defined Contribution Plan Disclosure [Line Items]
Percentage of defined contributions per employee	4.00%
High
Defined Contribution Plan Disclosure [Line Items]
Percentage of defined contributions per employee	12.00%

Statutory_Requirements_And_Div2

Statutory Requirements And Dividend Restrictions (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statutory Requirements And Dividend Restrictions [Line Items]
Period to notify the PRA, days	28 days
Retained earnings	$2,448,285,000	$2,193,133,000
Accumulated other comprehensive income	76,706,000	62,731,000	152,463,000
Contributed surplus	598,226,000	569,116,000
Low
Statutory Requirements And Dividend Restrictions [Line Items]
Required statutory capital	100,000,000
Armtech [Member]
Statutory Requirements And Dividend Restrictions [Line Items]
Payable dividend without prior regulatory approval	3,700,000	3,900,000
Endurance Bermuda
Statutory Requirements And Dividend Restrictions [Line Items]
Payable dividend without prior regulatory approval	$719,200,000	$654,500,000
Endurance US Subsidiaries
Statutory Requirements And Dividend Restrictions [Line Items]
Dividend payable rate, maximum	10.00%

Statutory_Requirements_And_Div3

Statutory Requirements And Dividend Restrictions (Combined Statutory Capital and Statutory Net Income (Loss)) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Other
Statutory Accounting Practices [Line Items]
Required statutory capital	$77,366	[1]	$63,369	[1]
Actual statutory capital	603,288	[1]	512,579	[1]
Statutory net income (loss)	14,103	[1]	-36,678	[1]	2,829	[1]
Bermuda
Statutory Accounting Practices [Line Items]
Required statutory capital	955,903	[2]	965,348	[2]
Actual statutory capital	2,876,927	[2]	2,618,198	[2]
Statutory net income (loss)	453,127		454,840		355,118
United States
Statutory Accounting Practices [Line Items]
Required statutory capital	244,587		236,652
Actual statutory capital	702,513		654,480
Statutory net income (loss)	$28,450		($48,035)		($147,325)
[1]	Includes Endurance U.K. and Endurance Bermudabs Singapore branch.
[2]	Bermuda statutory capital includes an investment in affiliate asset, which represents its interest in the remaining insurance and reinsurance operations of the Company included in the United States and Other columns above.

Taxes_Narrative_Details

Taxes (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Expense Benefit [Line Items]
Current income tax expense	($1,804,000)	($3,089,000)	($5,029,000)
Deferred income tax benefit (expense)	1,414,000	-2,764,000	1,683,000
Combined effective tax rate (Bermuda)	0.00%
Total income tax paid	900,000		1,600,000
Income tax refunds received		8,400,000
Valuation allowance	-121,409,000	-122,680,000
United States
Income Tax Expense Benefit [Line Items]
Current income tax expense	1,800,000	3,100,000	4,600,000
Deferred income tax benefit (expense)	-1,400,000	2,800,000	-1,600,000
Net operating loss carryforwards	192,000,000
United Kingdom [Member]
Income Tax Expense Benefit [Line Items]
Net operating loss carryforwards	57,300,000
Switzerland [Member]
Income Tax Expense Benefit [Line Items]
Net operating loss carryforwards	45,800,000
Singapore [Member]
Income Tax Expense Benefit [Line Items]
Net operating loss carryforwards	$46,000,000

Taxes_Income_Tax_Expense_Detai

Taxes (Income Tax Expense) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Current income tax expense	($1,804)	($3,089)	($5,029)
Deferred income tax benefit (expense)	1,414	-2,764	1,683
Income tax expense	($390)	($5,853)	($3,346)

Taxes_Income_Tax_Rate_Reconcil

Taxes (Income Tax Rate Reconciliation) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Computed expected tax expense	$0	$0	$0
Tax (expense) benefit effect on foreign taxes	-1,661	31,054	51,059
Change in valuation allowance	1,271	-36,907	-54,405
Income tax expense	($390)	($5,853)	($3,346)

Taxes_Schedule_Of_Net_Deferred

Taxes (Schedule Of Net Deferred Tax Assets And Liabilities) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Income Tax Disclosure [Abstract]
Unearned premiums	$23,124	$22,701
Loss reserves	29,410	32,109
Net operating loss carryforward	93,163	106,112
Deferred compensation	19,588	14,943
Deferred interest	44,951	43,341
Realized investment losses	125	150
Other	10,404	3,388
Total deferred income tax assets	220,765	222,744
Deferred acquisition costs	-10,843	-16,874
Unrealized investment (gains) losses	-5,293	30
Unrealized foreign exchange (gains) losses	-2,704	600
Temporary differences related to acquisition	-20,344	-22,612
Start up costs	-1,144	-720
Other	-10,033	-8,785
Total deferred income tax liabilities	-50,361	-48,361
Valuation allowance	-121,409	-122,680
Net deferred income tax asset	$48,995	$51,703

Taxes_Schedule_Of_Distribution

Taxes (Schedule Of Distribution Of Income Before Income Taxes) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Income Tax Disclosure [Abstract]
U.S. (domestic)	$60,112		$13,103		($186,882)
Non-U.S. (foreign)	288,728	[1]	304,665	[1]	352,744	[1]
Income before income taxes	$348,840		$317,768		$165,862
[1]	The Companybs non-U.S. (foreign) operating subsidiaries write business that is exposed to risks originating in the United States.

Condensed_Unaudited_Quarterly_2

Condensed Unaudited Quarterly Financial Data (Summary Of The Unaudited Quarterly Data) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Net premiums earned	$471,279	$514,895	$481,538	$396,266	$499,487	$553,545	$543,335	$420,117	$1,863,978	$2,016,484	$2,013,900
Net investment income	25,894	25,357	39,302	40,990	46,346	38,097	32,468	49,305	131,543	166,216	173,326
Net realized and unrealized gains (losses)	-3,788	9,788	3,411	4,872	5,197	-6,640	10,372	6,235	14,283	15,164	72,139
Net impairment losses recognized in earnings	-214	-102	-198	-111	-41	-190	-579	-806	-625	-1,616	-847
Subtotal	493,171	549,938	524,053	442,017	550,989	584,812	585,596	474,851
Net losses and loss expenses	243,801	290,269	259,196	176,896	302,620	339,036	359,058	218,970	970,162	1,219,684	1,520,995
Acquisition and general and administrative expenses	148,374	174,307	165,056	145,363	161,750	146,245	153,227	138,114
Net foreign exchange losses (gains)	-227	783	319	2,964	5,718	2,201	3,368	2,927	3,839	14,214	-15,911
Net income	84,573	76,234	83,163	104,480	67,181	83,416	61,019	100,299	348,450	311,915	162,516
Preferred dividends	-8,186	-8,188	-8,188	-8,188	-8,186	-8,188	-8,188	-8,188	-32,750	-32,750	-32,750
Net income available to common and participating common shareholders	$76,387	$68,046	$74,975	$96,292	$58,995	$75,228	$52,831	$92,111	$315,700	$279,165	$129,766
Basic earnings per share	$1.71	$1.52	$1.68	$2.16	$1.33	$1.70	$1.21	$2.13	$7.07	$6.37	$3
Diluted earnings per share	$1.70	$1.52	$1.68	$2.16	$1.33	$1.70	$1.21	$2.13	$7.06	$6.37	$3

Schedule_I_Summary_Of_Investme1

Schedule I Summary Of Investments Other Than Investments In Related Parties (Summary Of Investments Other Than Investments In Related Parties) (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	$5,732,629	[1]
Market Value	5,974,417
Amount at Which Shown on the Balance Sheet	5,974,417
U.S. government and government agencies and authorities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	582,970	[1]
Market Value	587,411
Amount at Which Shown on the Balance Sheet	587,411
States, municipalities and political subdivisions
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	39,340	[1]
Market Value	39,413
Amount at Which Shown on the Balance Sheet	39,413
Foreign governments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	239,217	[1]
Market Value	240,536
Amount at Which Shown on the Balance Sheet	240,536
Corporate bonds
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,401,806	[1]
Market Value	1,409,564
Amount at Which Shown on the Balance Sheet	1,409,564
Agency mortgage-backed securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,107,086	[1]
Market Value	1,133,123
Amount at Which Shown on the Balance Sheet	1,133,123
Non-agency mortgage-backed securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	1,003,048	[1]
Market Value	1,021,302
Amount at Which Shown on the Balance Sheet	1,021,302
Collateralized loan and debt obligations
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	247,510	[1]
Market Value	248,011
Amount at Which Shown on the Balance Sheet	248,011
Asset-backed securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	411,529	[1]
Market Value	413,221
Amount at Which Shown on the Balance Sheet	413,221
Fixed maturity securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	5,032,506	[1]
Market Value	5,092,581
Amount at Which Shown on the Balance Sheet	5,092,581
Short-term investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	9,015	[1]
Market Value	9,014
Amount at Which Shown on the Balance Sheet	9,014
Equity securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	303,922	[1]
Market Value	331,368
Amount at Which Shown on the Balance Sheet	331,368
Other investments
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Cost	387,186	[1]
Market Value	541,454
Amount at Which Shown on the Balance Sheet	$541,454
[1]	Investments in fixed maturity investments and short-term investments are shown at amortized cost.

Schedule_II_Condensed_Financia1

Schedule II Condensed Financial Statement Information Of The Registrant (Balance Sheets) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, except Share data, unless otherwise specified
Condensed Financial Statements, Captions [Line Items]
Common shares, ordinary, number of shares issued	44,765,153	44,368,742
Common Stock, Shares, Outstanding	44,765,153	44,368,742
Assets [Abstract]
Cash and cash equivalents	$745,472	$845,851	$1,124,019	$890,914
Other assets	199,375	179,109
Total assets	9,644,782	8,978,122
Liabilities [Abstract]
Debt	527,715	527,478
Other liabilities	287,978	213,419
Total liabilities	6,459,600	6,091,573
Stockholders' Equity Attributable to Parent [Abstract]
Preferred shares Series A and Series B, non-cumulative - 17,200,000 issued and outstanding (2013 - 17,200,000)	17,200	17,200
Common shares Ordinary - 44,765,153 issued and outstanding (2013 - 44,368,742)	44,765	44,369
Additional paid-in capital	598,226	569,116
Accumulated other comprehensive income	76,706	62,731	152,463
Retained earnings	2,448,285	2,193,133
Total shareholdersb equity	3,185,182	2,886,549	2,710,597
Total liabilities and shareholdersb equity	9,644,782	8,978,122
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Preferred Stock, Shares Issued	17,200,000	17,200,000
Preferred Stock, Shares Outstanding	17,200,000	17,200,000
Common shares, ordinary, number of shares issued	44,765,153	44,368,742
Common Stock, Shares, Outstanding	44,765,153	44,368,742
Assets [Abstract]
Investment in subsidiary	3,518,589	3,211,570
Cash and cash equivalents	240	6,517	10,083	1,230
Amounts due from subsidiaries	201,600	200,530
Other assets	13,927	15,496
Total assets	3,734,356	3,434,113
Liabilities [Abstract]
Debt	527,616	527,398
Other liabilities	21,558	20,166
Total liabilities	549,174	547,564
Stockholders' Equity Attributable to Parent [Abstract]
Preferred shares Series A and Series B, non-cumulative - 17,200,000 issued and outstanding (2013 - 17,200,000)	17,200	17,200
Common shares Ordinary - 44,765,153 issued and outstanding (2013 - 44,368,742)	44,765	44,369
Additional paid-in capital	598,226	569,116
Accumulated other comprehensive income	76,706	62,731
Retained earnings	2,448,285	2,193,133
Total shareholdersb equity	3,185,182	2,886,549
Total liabilities and shareholdersb equity	$3,734,356	$3,434,113

Schedule_II_Condensed_Financia2

Schedule II Condensed Financial Statement Information Of The Registrant (Statements of Income) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues
Net investment income (loss)	$25,894	$25,357	$39,302	$40,990	$46,346	$38,097	$32,468	$49,305	$131,543	$166,216	$173,326
Net realized and unrealized gains (losses)	-3,788	9,788	3,411	4,872	5,197	-6,640	10,372	6,235	14,283	15,164	72,139
Total revenues									2,003,393	2,194,202	2,256,335
Expenses
General and administrative expenses									313,587	294,906	235,689
Net foreign exchange (gains) losses	-227	783	319	2,964	5,718	2,201	3,368	2,927	3,839	14,214	-15,911
Interest expense									40,968	36,188	36,174
Net income	84,573	76,234	83,163	104,480	67,181	83,416	61,019	100,299	348,450	311,915	162,516
Preferred dividends	-8,186	-8,188	-8,188	-8,188	-8,186	-8,188	-8,188	-8,188	-32,750	-32,750	-32,750
Net income available to common and participating common shareholders	76,387	68,046	74,975	96,292	58,995	75,228	52,831	92,111	315,700	279,165	129,766
Parent Company [Member]
Revenues
Net investment income (loss)									248	0	-2
Net realized and unrealized gains (losses)									1,957	-1,511	-74
Other income									10,200	10,200	11,083
Total revenues									12,405	8,689	11,007
Expenses
General and administrative expenses									61,325	48,017	17,923
Net foreign exchange (gains) losses									-1	0	2
Interest expense									40,968	36,188	36,174
Total expenses									102,292	84,205	54,099
Net loss before equity in net income of subsidiaries									-89,887	-75,516	-43,092
Equity in net income of subsidiaries									438,337	387,431	205,608
Net income									348,450	311,915	162,516
Preferred dividends									-32,750	-32,750	-32,750
Net income available to common and participating common shareholders									$315,700	$279,165	$129,766

Schedule_II_Condensed_Financia3

Schedule II Condensed Financial Statement Information Of The Registrant (Statements Of Cash Flows) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net cash used in operating activities
Net income	$348,450	$311,915	$162,516
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	27,234	21,250	22,678
Net realized and unrealized (gains) losses	-14,283	-15,164	-72,139
Stock-based compensation expense	31,006	27,988	11,211
Other assets	-17,132	-10,372	19,464
Other liabilities	127,036	54,376	-3,180
Net cash flows provided by operating activities	266,261	157,924	283,468
Net cash flows (used in) provided by investing activities
Proceeds from sales of available for sale investments	3,557,450	3,374,002	4,143,528
Purchases of available for sale investments	-4,449,225	-4,259,800	-4,964,345
Purchases of fixed assets	-40,932	-24,960	-23,855
Net cash flows (used in) provided by investing activities	-236,881	-347,777	46,302
Cash flows used in financing activities:
Repayment of long term debt	-686	-768	-2,017
Issuance of common shares	2,305	31,884	2,935
Bridge facility costs paid	-4,750	0	0
Repurchase of common shares	0	-14,584	-10,005
Settlement of restricted shares	-4,039	-3,001	-3,272
Dividends paid on preferred shares	-32,750	-32,750	-32,750
Dividends paid on common shares	-60,524	-55,906	-53,439
Net cash flows used in financing activities	-99,738	-74,422	-97,576
Net (decrease) increase in cash and cash equivalents	-100,379	-278,168	233,105
Cash and cash equivalents, beginning of year	845,851	1,124,019	890,914
Cash and cash equivalents, end of year	745,472	845,851	1,124,019
Parent Company [Member]
Net cash used in operating activities
Net income	348,450	311,915	162,516
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	6,785	1,504	1,095
Net realized and unrealized (gains) losses	-1,957	1,511	74
Stock-based compensation expense	15,093	20,708	4,819
Equity in net earnings of subsidiary	-438,337	-387,431	-205,608
Other assets	-177	2,112	-2,614
Other liabilities	1,626	2,942	-2,136
Net cash flows provided by operating activities	-68,517	-46,739	-41,854
Net cash flows (used in) provided by investing activities
Proceeds from sales of available for sale investments	26,094	0	0
Purchases of available for sale investments	-24,137	0	0
Contributions of capital made to subsidiaries	0	-10,389	0
Returns of capital received from subsidiaries	0	10,289	0
Dividends received from subsidiary	145,203	118,278	126,550
Net amounts received from subsidiaries	14,819	7,650	21,760
Purchases of fixed assets	0	-8,298	0
Proceeds from disposals of fixed assets	19	0	0
Net cash flows (used in) provided by investing activities	161,998	117,530	148,310
Cash flows used in financing activities:
Repayment of long term debt	0	0	-1,072
Issuance of common shares	2,305	31,884	2,935
Bridge facility costs paid	-4,750	0	0
Repurchase of common shares	0	-14,584	-10,005
Settlement of restricted shares	-4,039	-3,001	-3,272
Dividends paid on preferred shares	-32,750	-32,750	-32,750
Dividends paid on common shares	-60,524	-55,906	-53,439
Net cash flows used in financing activities	-99,758	-74,357	-97,603
Net (decrease) increase in cash and cash equivalents	-6,277	-3,566	8,853
Cash and cash equivalents, beginning of year	6,517	10,083	1,230
Cash and cash equivalents, end of year	$240	$6,517	$10,083

Schedule_III_Supplementary_Ins1

Schedule III Supplementary Insurance Information (Supplementary Insurance Information) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Supplementary Insurance Information, by Segment [Line Items]
Deferred Acquisition Costs	$207,368		$186,027		$168,252
Reserve for Losses and Loss Expenses	3,846,859		4,002,259		4,240,876
Unearned Premiums	1,254,519		1,018,851		965,244
Net Premiums Earned	1,863,978		2,016,484		2,013,900
Net Investment Income	131,543	[1]	166,216	[1]	173,326	[1]
Net Losses and Loss Expenses	970,162		1,219,684		1,520,995
Amortization of Deferred Acquisition Costs	319,513		304,430		303,179
Other Operating Expenses	313,587	[2]	294,906	[2]	235,689	[2]
Net Premiums Written	1,934,206		2,048,933		2,029,495
Reinsurance
Supplementary Insurance Information, by Segment [Line Items]
Deferred Acquisition Costs	172,787		155,932		136,632
Reserve for Losses and Loss Expenses	1,723,087		1,843,369		1,953,824
Unearned Premiums	611,740		566,738		515,769
Net Premiums Earned	1,030,066		1,070,010		1,058,811
Net Investment Income	0	[1]	0	[1]	0	[1]
Net Losses and Loss Expenses	375,601		445,259		665,054
Amortization of Deferred Acquisition Costs	254,145		239,652		227,582
Other Operating Expenses	139,012	[2]	137,310	[2]	110,581	[2]
Net Premiums Written	1,073,800		1,116,423		1,087,138
Insurance
Supplementary Insurance Information, by Segment [Line Items]
Deferred Acquisition Costs	34,581		30,095		31,620
Reserve for Losses and Loss Expenses	2,123,772		2,158,890		2,287,052
Unearned Premiums	642,779		452,113		449,475
Net Premiums Earned	833,912		946,474		955,089
Net Investment Income	0	[1]	0	[1]	0	[1]
Net Losses and Loss Expenses	594,561		774,425		855,941
Amortization of Deferred Acquisition Costs	65,368		64,778		75,597
Other Operating Expenses	174,575	[2]	157,596	[2]	125,108	[2]
Net Premiums Written	$860,406		$932,510		$942,357
[1]	Because the Company does not manage its assets by segment, investment income is not allocated to the individual segments.
[2]	General and administrative expenses incurred by segments are allocated directly. Remaining corporate overhead is allocated to segments primarily based on estimated consumption, headcount and other variables deemed relevant to the allocation of such expenses.

Schedule_IV_Reinsurance_Summar

Schedule IV Reinsurance (Summary Of Reinsurance) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross	$1,716,128	$1,475,429	$1,429,930
Ceded to Other Companies	959,870	616,311	519,531
Assumed from Other Companies	1,177,948	1,189,815	1,119,096
Net premiums written	1,934,206	2,048,933	2,029,495
Property and liability insurance
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross	1,716,128	1,475,429	1,429,930
Ceded to Other Companies	959,870	616,311	519,531
Assumed from Other Companies	1,177,948	1,189,815	1,119,096
Net premiums written	$1,934,206	$2,048,933	$2,029,495
Percentage of Amount Assumed to Net	61.00%	58.00%	55.00%

Schedule_VI_Underwriters_Sched

Schedule VI Underwriters (Schedule Of Underwriters) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred Acquisition Costs	$207,368		$186,027		$168,252
Reserve for Losses and Loss Expenses	3,846,859		4,002,259		4,240,876
Discount if any, Reserve for Losses and Loss Expenses	0		0		0
Unearned Premiums	1,254,519		1,018,851		965,244
Net Premiums Earned	1,863,978		2,016,484		2,013,900
Net Investment Income	131,543	[1]	166,216	[1]	173,326	[1]
Incurred related to Current year	1,203,977		1,442,076		1,641,152
Net Losses And Loss Expenses, Prior Year	233,815		222,392		120,157
Amortization of Deferred Acquisition Costs	319,513		304,430		303,179
Paid Losses and Loss Expenses	1,158,212		1,362,092		1,323,756
Net Premiums Written	1,934,206		2,048,933		2,029,495
Reinsurance
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred Acquisition Costs	172,787		155,932		136,632
Reserve for Losses and Loss Expenses	1,723,087		1,843,369		1,953,824
Discount if any, Reserve for Losses and Loss Expenses	0		0		0
Unearned Premiums	611,740		566,738		515,769
Net Premiums Earned	1,030,066		1,070,010		1,058,811
Net Investment Income	0	[1]	0	[1]	0	[1]
Incurred related to Current year	528,846		633,748		739,025
Net Losses And Loss Expenses, Prior Year	-153,245		-188,489		-73,971
Amortization of Deferred Acquisition Costs	254,145		239,652		227,582
Paid Losses and Loss Expenses	457,636		564,782		608,447
Net Premiums Written	1,073,800		1,116,423		1,087,138
Insurance
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred Acquisition Costs	34,581		30,095		31,620
Reserve for Losses and Loss Expenses	2,123,772		2,158,890		2,287,052
Discount if any, Reserve for Losses and Loss Expenses	0		0		0
Unearned Premiums	642,779		452,113		449,475
Net Premiums Earned	833,912		946,474		955,089
Net Investment Income	0	[1]	0	[1]	0	[1]
Incurred related to Current year	675,131		808,328		902,127
Net Losses And Loss Expenses, Prior Year	-80,570		-33,903		-46,186
Amortization of Deferred Acquisition Costs	65,368		64,778		75,597
Paid Losses and Loss Expenses	700,576		797,310		715,309
Net Premiums Written	$860,406		$932,510		$942,357
[1]	Because the Company does not manage its assets by segment, investment income is not allocated to the individual segments.