W. R. Berkley (WRB) 10-Q 7 Nov 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Oct. 31, 2014
Document and Entity Information [Abstract]	'	'
Entity Registrant Name	'BERKLEY W R CORP	'
Entity Central Index Key	'0000011544	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	126,909,538

Consolidated_Balance_Sheet_Con

Consolidated Balance Sheet Consolidated Balance Sheet (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets [Abstract]	'	'
Fixed maturity securities	$12,397,756	$11,616,844
Equity securities	222,024	283,338
Arbitrage trading account	918,223	522,128
Investment funds	1,020,132	1,067,495
Loans receivable	343,300	343,583
Real estate	703,994	715,242
Total investments	15,605,429	14,548,630
Cash and cash equivalents	1,342,285	839,738
Premiums and fees receivable	1,681,674	1,557,480
Due from reinsurers	1,452,393	1,533,103
Accrued investment income	138,904	118,329
Prepaid reinsurance premiums	418,081	367,803
Deferred policy acquisition costs	492,500	452,101
Property, furniture and equipment	333,938	339,448
Federal and foreign income taxes	0	44,857
Goodwill	103,337	110,146
Trading account receivables from brokers and clearing organizations	0	304,936
Other assets	529,056	335,225
Total assets	22,097,597	20,551,796
Liabilities:	'	'
Reserves for losses and loss expenses	10,314,265	10,080,941
Unearned premiums	3,111,013	2,781,437
Due to reinsurers	255,430	276,755
Trading account securities sold but not yet purchased	159,537	162,278
Payables to Broker-Dealers and Clearing Organizations	95,681	0
Federal and foreign income taxes	17,618	0
Other liabilities	938,554	848,749
Junior subordinated debentures	339,995	339,800
Senior notes and other debt	2,122,030	1,692,442
Total liabilities	17,354,123	16,182,402
Equity:	'	'
Authorized 5,000,000 shares; issued and outstanding - none	0	0
Authorized 500,000,000 shares, issued and outstanding, net of treasury shares, 126,907,538 and 132,233,167 shares, respectively	47,024	47,024
Additional paid-in capital	982,104	967,440
Retained earnings	5,762,406	5,265,015
Accumulated other comprehensive income	273,545	189,391
Treasury stock, at cost, 108,210,380 and 102,884,751 shares, respectively	2,356,176	2,132,835
Total stockholders’ equity	4,708,903	4,336,035
Noncontrolling interests	34,571	33,359
Total equity	4,743,474	4,369,394
Total liabilities and equity	$22,097,597	$20,551,796

Consolidated_Balance_Sheet_Con1

Consolidated Balance Sheet Consolidated Balance Sheet (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]	'	'
Preferred stock, par value $.10 per share:	$0.10	$0.10
Preferred shares authorized	5,000,000	5,000,000
Preferred shares issued	0	0
Preferred shares outstanding	0	0
Common stock, par value $.20 per share:	$0.20	$0.20
Common shares authorized	500,000,000	500,000,000
Common shares issued	127,613,325	132,233,167
Common shares outstanding	127,613,325	132,233,167
Treasury stock issued at cost	107,504,593	102,884,751

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
REVENUES:	'	'	'	'
Net premiums written	$1,525,382	$1,423,625	$4,541,038	$4,142,489
Change in net unearned premiums	-64,578	-94,763	-298,977	-298,993
Net premiums earned	1,460,804	1,328,862	4,242,061	3,843,496
Net investment income	179,225	125,634	486,665	405,300
Insurance service fees	26,345	26,121	81,970	80,509
Net investment gains	72,258	43,869	234,180	96,896
Revenues from wholly-owned investees	101,568	109,390	298,693	284,900
Other income	405	248	931	754
Total revenues	1,840,605	1,634,124	5,344,500	4,711,855
OPERATING COSTS AND EXPENSES:	'	'	'	'
Losses and loss expenses	887,123	798,276	2,576,996	2,348,425
Other operating costs and expenses	544,303	504,096	1,593,619	1,479,986
Expenses from wholly-owned investees	97,797	103,170	290,823	273,615
Interest expense	32,929	30,349	93,570	92,667
Total operating costs and expenses	1,562,152	1,435,891	4,555,008	4,194,693
Income before income taxes	278,453	198,233	789,492	517,162
Income tax expense	-89,662	-60,045	-250,840	-147,249
Net income before noncontrolling interests	188,791	138,188	538,652	369,913
Noncontrolling interests	-252	-1,214	-479	-367
Net income to common stockholders	$188,539	$136,974	$538,173	$369,546
NET INCOME PER SHARE:	'	'	'	'
Basic	$1.48	$1.01	$4.20	$2.72
Diluted	$1.42	$0.97	$4.02	$2.62

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income Statement (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net income before noncontrolling interests	$188,791	$138,188	$538,652	$369,913
Other comprehensive income (loss):	'	'	'	'
Change in unrealized currency translation adjustments	-49,380	44,328	-28,590	-25,451
Change in unrealized investment gains (losses), net of taxes	-12,912	-38,879	108,232	-228,129
Change in net pension asset, net of taxes	2,020	1,814	4,631	5,442
Other comprehensive income (loss)	-60,272	7,263	84,273	-248,138
Comprehensive income	128,519	145,451	622,925	121,775
Comprehensive (income) to the noncontrolling interest	-334	-1,223	-598	-381
Comprehensive income to common stockholders	$128,185	$144,228	$622,327	$121,394

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity Statement (USD $)	Total	Common stocks	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	Accumulated Translation Adjustment [Member]	Accumulated Defined Benefit Plans Adjustment [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
In Thousands, unless otherwise specified
Beginning and end of period at Dec. 31, 2012	'	$47,024	$945,166	$4,817,807	$517,658	($36,676)	($15,351)	'	($1,969,411)	$29,249
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'	'	'	'
Options exercised and restricted stock units issued, net of tax	'	'	-1,428	'	'	'	'	'	'	'
Restricted stock units expensed	'	'	17,031	'	'	'	'	'	'	'
Stock issued to directors	'	'	535	'	'	'	'	'	597	'
Net income before noncontrolling interests	369,913	'	'	369,546	'	'	'	'	'	367
Dividends	'	'	'	-39,336	'	'	'	'	'	'
Change in unrealized investment gains (losses), net of taxes	-228,129	'	'	'	-228,677	'	'	'	'	'
Unrealized gains on other-than-temporarily impaired securities	'	'	'	'	534	'	'	'	'	'
Change in unrealized currency translation adjustments	-25,451	'	'	'	'	-25,451	'	'	'	'
Change in net pension asset, net of taxes	5,442	'	'	'	'	'	5,442	'	'	'
Stock exercised/vested	'	'	'	'	'	'	'	'	1,434	'
Stock repurchased	'	'	'	'	'	'	'	'	-39,370	'
Stock issued to directors	'	'	535	'	'	'	'	'	597	'
Contributions	'	'	'	'	'	'	'	'	'	-1,406
Other comprehensive income (loss)	-248,138	'	'	'	'	-25,451	5,442	-248,138	'	14
End of period at Sep. 30, 2013	'	'	961,304	5,148,017	289,515	-62,127	-9,909	217,479	-2,006,750	28,224
Beginning and end of period at Jun. 30, 2013	'	'	'	'	'	'	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'	'	'	'
Net income before noncontrolling interests	138,188	'	'	'	'	'	'	'	'	'
Change in unrealized investment gains (losses), net of taxes	-38,879	'	'	'	'	'	'	'	'	'
Change in unrealized currency translation adjustments	44,328	'	'	'	'	'	'	'	'	'
Change in net pension asset, net of taxes	1,814	'	'	'	'	'	'	'	'	'
Other comprehensive income (loss)	7,263	'	'	'	'	44,328	1,814	7,263	'	'
End of period at Sep. 30, 2013	'	'	'	'	'	-62,127	-9,909	217,479	'	'
Beginning and end of period at Dec. 31, 2013	4,369,394	47,024	967,440	5,265,015	256,566	-60,524	-6,651	'	-2,132,835	33,359
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'	'	'	'
Options exercised and restricted stock units issued, net of tax	'	'	-6,383	'	'	'	'	'	'	'
Restricted stock units expensed	'	'	20,456	'	'	'	'	'	'	'
Stock issued to directors	'	'	591	'	'	'	'	'	594	'
Net income before noncontrolling interests	538,652	'	'	538,173	'	'	'	'	'	479
Dividends	'	'	'	-40,782	'	'	'	'	'	'
Change in unrealized investment gains (losses), net of taxes	108,232	'	'	'	107,501	'	'	'	'	'
Unrealized gains on other-than-temporarily impaired securities	'	'	'	'	612	'	'	'	'	'
Change in unrealized currency translation adjustments	-28,590	'	'	'	'	-28,590	'	'	'	'
Change in net pension asset, net of taxes	4,631	'	'	'	'	'	4,631	'	'	'
Stock exercised/vested	'	'	'	'	'	'	'	'	6,384	'
Stock repurchased	'	'	'	'	'	'	'	'	-230,319	'
Stock issued to directors	'	'	591	'	'	'	'	'	594	'
Contributions	'	'	'	'	'	'	'	'	'	614
Other comprehensive income (loss)	84,273	'	'	'	'	-28,590	4,631	84,273	'	119
End of period at Sep. 30, 2014	4,743,474	'	982,104	5,762,406	364,679	-89,114	-2,020	273,545	-2,356,176	34,571
Beginning and end of period at Jun. 30, 2014	'	'	'	'	'	'	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'	'	'	'
Net income before noncontrolling interests	188,791	'	'	'	'	'	'	'	'	'
Change in unrealized investment gains (losses), net of taxes	-12,912	'	'	'	'	'	'	'	'	'
Change in unrealized currency translation adjustments	-49,380	'	'	'	'	'	'	'	'	'
Change in net pension asset, net of taxes	2,020	'	'	'	'	'	'	'	'	'
Other comprehensive income (loss)	-60,272	'	'	'	'	-49,380	2,020	-60,272	'	'
End of period at Sep. 30, 2014	$4,743,474	'	'	'	'	($89,114)	($2,020)	$273,545	'	'

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
CASH FROM (USED IN) OPERATING ACTIVITIES:	'	'
Net income to common stockholders	$538,173	$369,546
Adjustments to reconcile net income to net cash from operating activities:	'	'
Net investment gains	-234,180	-96,896
Depreciation and amortization	63,415	80,049
Noncontrolling interests	479	367
Investment funds	-150,502	-48,299
Stock incentive plans	21,549	18,163
Change in:	'	'
Arbitrage trading account	1,781	-249
Premiums and fees receivable	-125,319	-161,660
Reinsurance accounts	12,967	-168,863
Deferred policy acquisition costs	-44,087	-51,629
Income taxes	11,092	-25,396
Reserves for losses and loss expenses	277,542	341,266
Unearned premiums	345,521	363,354
Other	-143,645	6,942
Net cash from operating activities	574,786	626,695
CASH USED IN INVESTING ACTIVITIES:	'	'
Proceeds from sale of fixed maturity securities	546,970	891,357
Proceeds from sale of equity securities	109,928	222,396
Distributions from (contributions to) investment funds	285,233	-57,812
Proceeds from maturities and prepayments of fixed maturity securities	1,887,252	2,244,665
Purchase of fixed maturity securities	-3,098,477	-3,198,204
Purchase of equity securities	-28,606	-184,829
Additions to real estate	-253,007	-47,279
SEC Schedule III, Real Estate, Cost of Real Estate Sold	343,723	0
Change in loans receivable	320	-99,356
Net additions to property, furniture and equipment	-30,797	-49,425
Change in balances due to security brokers	68,411	-37,554
Gain (Loss) on Disposition of Business	15,612	-21,408
Payment for business purchased, net of cash acquired	-65,423	-38,556
Net cash used in investing activities	-218,861	-376,005
CASH USED IN (FROM) FINANCING ACTIVITIES:	'	'
Repayment of senior notes and other debt	-1,829	-463,600
Proceeds from Issuance of Debt	431,409	349,423
Cash dividends to common stockholders	-40,784	-39,336
Purchase of common treasury shares	-236,703	-39,370
Other, net	915	7,341
Net cash used in (from) financing activities	153,008	-185,542
Net impact on cash due to change in foreign exchange rates	-6,386	-4,492
Net change in cash and cash equivalents	502,547	60,656
Cash and cash equivalents at beginning of year	839,738	905,670
Cash and cash equivalents at end of period	$1,342,285	$966,326

General_General

General General	9 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	'
	General
	The accompanying unaudited consolidated financial statements of W. R. Berkley Corporation and its subsidiaries (the “Company”) have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all the information and notes required by GAAP for annual financial statements. The unaudited consolidated financial statements reflect all adjustments, consisting only of normal recurring items, which are necessary to present fairly the Company’s financial position and results of operations on a basis consistent with the prior audited consolidated financial statements. Operating results for interim periods are not necessarily indicative of the results that may be expected for the year. All significant intercompany accounts and transactions have been eliminated. The preparation of financial statements requires the use of management estimates. For further information related to a description of areas of judgment and estimates and other information necessary to understand the Company’s financial position and results of operations, refer to the audited consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013. Reclassifications have been made in the 2013 financial statements as originally reported to conform to the presentation of the 2014 financial statements.
	The income tax provision has been computed based on the Company’s estimated annual effective tax rate. The effective tax rate for the quarter differs from the federal income tax rate of 35% principally because of tax-exempt investment income.

Per_Share_Data_Per_Share_Data

Per Share Data Per Share Data	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	Per Share Data
	The Company presents both basic and diluted net income per share (“EPS”) amounts. Basic EPS is calculated by dividing net income by the weighted average number of common shares outstanding during the period. Diluted EPS is based upon the weighted average number of common and common equivalent shares outstanding during the period and is calculated using the treasury stock method for stock incentive plans. Common equivalent shares are excluded from the computation in periods in which they have an anti-dilutive effect.
	The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows:
		For the Three Months		For the Nine Months
		Ended September 30,		Ended September 30,
	(In thousands)	2014	2013	2014	2013
	Basic	127,165	135,268	128,225	135,726
	Diluted	133,001	140,758	133,886	141,095

Recent_Accounting_Pronouncemen

Recent Accounting Pronouncements Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	In January 2014, the Financial Accounting Standards Board issued guidance relating to Accounting for Investments in Qualified Affordable Housing Projects. This guidance modified the amortization method on these investments and the statement of operations classification as pre-adoption amounts were presented in both pre-tax income and income tax expense while post adoption all impacts are recorded in income tax expense. The Company adopted this guidance effective January 1, 2014, and the impact of applying this guidance was immaterial.
	All recently issued but not yet effective accounting and reporting standards are either not applicable to the Company or are not expected to have a material impact on the Company.

Acquistions_Acquisitions

Acquistions Acquisitions	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Business Combination Disclosure	'
	Acquisitions/Dispositions
	In 2014, the Company acquired a specialty property and casualty insurance distribution company for $83 million. The fair values of the assets acquired and liabilities assumed have been estimated based on a preliminary valuation. The fair values of the assets and liabilities will be adjusted, as needed, following completion of a final valuation.
	In 2012, the Company acquired a 49% interest in a worldwide supplier of after-market original equipment manufacturer (OEM) parts, systems and custom logistic support services for military aircraft operations for $43 million. In 2013, the Company acquired the remaining 51% of this business for $43 million. The estimated useful lives of the intangible assets acquired range from 2 years to 15 years, with approximately $3 million having an indefinite life.
	In 2014, the Company sold an aviation-related business for $16 million. The business had a net carrying value of $15 million.
	The following table summarizes the estimated fair value of net assets acquired and liabilities assumed for business combinations completed in 2014 and 2013:
		September 30,			December 31,
	(In thousands)	2014			2013
	Cash and cash equivalents	$	17,456		$	3,911
	Real estate, furniture and equipment	669			898
	Goodwill and other intangibles assets	77,967			64,464
	Premium and service fee receivable	20,178			—
	Other assets	—			60,661
	Total assets acquired	116,270			129,934
	Debt	—			(27,612		)
	Other liabilities assumed	(33,391		)	(17,076		)
	Net assets acquired	$	82,879		$	85,246

Statements_of_Comprehensive_In

Statements of Comprehensive Income (Loss) Statements of Comprehensive Income (Loss) (Notes)	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Comprehensive Income (Loss)	'
	Statement of Comprehensive Income (Loss)
	The following table presents the components of the changes in accumulated other comprehensive income (loss) ("AOCI"):
	(In thousands)	Unrealized Investment Gains (Losses)				Currency Translation Adjustments			Net Pension Asset				Accumulated Other Comprehensive Income (Loss)
	As of and for the nine months ended September 30, 2014:
	Changes in AOCI
	Beginning of period	$	256,566			$	(60,524	)	$	(6,651	)		$	189,391
	Other comprehensive income (loss) before reclassifications	143,388				(28,590		)	—				114,798
	Amounts reclassified from AOCI	(35,156		)		—			4,631				(30,525		)
	Other comprehensive income (loss)	108,232				(28,590		)	4,631				84,273
	Unrealized investment gain (loss) related to non-controlling interest	(119		)		—			—				(119		)
	End of period	$	364,679			$	(89,114	)	$	(2,020	)		$	273,545
	Amounts reclassified from AOCI
	Pre-tax	$	(54,086	)	-1	$	—		$	7,125		-2	$	(46,961	)
	Tax effect (3)	18,930				—			(2,494		)		16,436
	After-tax amounts reclassified	$	(35,156	)		$	—		$	4,631			$	(30,525	)
	Other comprehensive income (loss)
	Pre-tax	$	163,651			$	(28,590	)	$	7,125			$	142,186
	Tax effect	(55,419		)		—			(2,494		)		(57,913		)
	Other comprehensive income (loss)	$	108,232			$	(28,590	)	$	4,631			$	84,273
	As of and for the three months ended September 30, 2014:
	Changes in AOCI
	Beginning of period	$	377,673			$	(39,734	)	$	(4,040	)		$	333,899
	Other comprehensive income (loss) before reclassifications	3,099				(49,380		)	—				(46,281		)
	Amounts reclassified from AOCI	(16,011		)		—			2,020				(13,991		)
	Other comprehensive income (loss)	(12,912		)		(49,380		)	2,020				(60,272		)
	Unrealized investment gain (loss) related to non-controlling interest	(82		)		—			—				(82		)
	End of period	$	364,679			$	(89,114	)	$	(2,020	)		$	273,545
	Amounts reclassified from AOCI
	Pre-tax	$	(24,632	)	-1	$	—		$	3,108		-2	$	(21,524	)
	Tax effect (3)	8,621				—			(1,088		)		7,533
	After-tax amounts reclassified	$	(16,011	)		$	—		$	2,020			$	(13,991	)
	Other comprehensive income (loss)
	Pre-tax	$	(25,029	)		$	(49,380	)	$	3,108			$	(71,301	)
	Tax effect	12,117				—			(1,088		)		11,029
	Other comprehensive income (loss)	$	(12,912	)		$	(49,380	)	$	2,020			$	(60,272	)
		Unrealized Investment Gains (Losses)				Currency Translation Adjustments			Net Pension Asset				Accumulated Other Comprehensive Income (Loss)
	(In thousands)
	As of and for the nine months ended September 30, 2013:
	Changes in AOCI
	Beginning of period	$	517,658			$	(36,676	)	$	(15,351	)		$	465,631
	Other comprehensive income (loss) before reclassifications	(172,276		)		(25,451		)	—				(197,727		)
	Amounts reclassified from AOCI	(55,853		)		—			5,442				(50,411		)
	Other comprehensive income (loss)	(228,129		)		(25,451		)	5,442				(248,138		)
	Unrealized investment gain related to non-controlling interest	(14		)		—			—				(14		)
	End of period	$	289,515			$	(62,127	)	$	(9,909	)		$	217,479
	Amounts reclassified from AOCI
	Pre-tax	$	(85,928	)	-1	$	—		$	8,372		-2	$	(77,556	)
	Tax effect (3)	30,075				—			(2,930		)		27,145
	After-tax amounts reclassified	$	(55,853	)		$	—		$	5,442			$	(50,411	)
	Other comprehensive income (loss)
	Pre-tax	$	(350,968	)		$	(25,451	)	$	8,372			$	(368,047	)
	Tax effect	122,839				—			(2,930		)		119,909
	Other comprehensive income (loss)	$	(228,129	)		$	(25,451	)	$	5,442			$	(248,138	)
	As of and for the three months ended September 30, 2013:
	Changes in AOCI
	Beginning of period	$	328,403			$	(106,455	)	$	(11,723	)		$	210,225
	Other comprehensive income (loss) before reclassifications	(10,331		)		44,328			—				33,997
	Amounts reclassified from AOCI	(28,548		)		—			1,814				(26,734		)
	Other comprehensive income (loss)	(38,879		)		44,328			1,814				7,263
	Unrealized investment gain related to non-controlling interest	(9		)		—			—				(9		)
	End of period	$	289,515			$	(62,127	)	$	(9,909	)		$	217,479
	Amounts reclassified from AOCI
	Pre-tax	$	(43,920	)	-1	$	—		$	2,790		-2	$	(41,130	)
Tax effect (3)	15,372				—			(976		)		14,396
After-tax amounts reclassified	$	(28,548	)		$	—		$	1,814			$	(26,734	)
Other comprehensive income (loss)
Pre-tax	$	(59,814	)		$	44,328		$	2,790			$	(12,696	)
Tax effect	20,935				—			(976		)		19,959
Other comprehensive income (loss)	$	(38,879	)		$	44,328		$	1,814			$	7,263
_______________
(1) Net investment gains in the consolidated statements of income.
(2) Other operating costs and expenses in the consolidated statements of income.
(3) Income tax expense in the consolidated statements of income.

Statements_of_Cash_Flow_Statem

Statements of Cash Flow Statements of Cash Flow	9 Months Ended
	Sep. 30, 2014
Supplemental Cash Flow Elements [Abstract]	'
Cash Flow, Supplemental Disclosures	'
	Statements of Cash Flow
	Interest payments were $108,688,000 and $114,026,000 and income taxes paid were $238,030,000 and $176,632,000 in the nine months ended September 30, 2014 and 2013, respectively.

Investments_In_Fixed_Maturity_

Investments In Fixed Maturity Securities (Debt Securities [Member])	9 Months Ended
	Sep. 30, 2014
Debt Securities [Member]	'
Schedule of Marketable Securities [Line Items]	'
Investments In Fixed Maturity Securities	'
	Investments in Fixed Maturity Securities
	At September 30, 2014 and December 31, 2013, investments in fixed maturity securities were as follows:
	(In thousands)	Amortized		Gross Unrealized					Fair		Carrying
		Cost		Gains		Losses			Value		Value
	September 30, 2014
	Held to maturity:
	State and municipal	$	71,897	$	16,991	$	—		$	88,888	$	71,897
	Residential mortgage-backed	24,300		2,901		—			27,201		24,300
	Corporate	4,999		368		—			5,367		4,999
	Total held to maturity	101,196		20,260		—			121,456		101,196
	Available for sale:
	U.S. government and government agency	787,967		30,296		(5,229		)	813,034		813,034
	State and municipal	3,958,141		226,746		(4,819		)	4,180,068		4,180,068
	Mortgage-backed securities:
	Residential (1)	1,209,068		26,100		(14,209		)	1,220,959		1,220,959
	Commercial	76,993		976		(83		)	77,886		77,886
	Corporate	4,866,983		191,727		(17,008		)	5,041,702		5,041,702
	Foreign	880,959		95,159		(13,207		)	962,911		962,911
	Total available for sale	11,780,111		571,004		(54,555		)	12,296,560		12,296,560
	Total investments in fixed maturity securities	$	11,881,307	$	591,264	$	(54,555	)	$	12,418,016	$	12,397,756
	December 31, 2013
	Held to maturity:
	State and municipal	$	68,929	$	11,172	$	—		$	80,101	$	68,929
	Residential mortgage-backed	27,393		3,311		—			30,704		27,393
	Corporate	4,998		417		—			5,415		4,998
	Total held to maturity	101,320		14,900		—			116,220		101,320
	Available for sale:
	U.S. government and government agency	858,319		34,522		(7,982		)	884,859		884,859
	State and municipal	4,085,791		162,330		(29,837		)	4,218,284		4,218,284
	Mortgage-backed securities:
	Residential (1)	1,248,693		25,895		(25,941		)	1,248,647		1,248,647
	Commercial	76,454		5,670		(988		)	81,136		81,136
	Corporate	4,076,585		156,256		(30,100		)	4,202,741		4,202,741
	Foreign	844,469		51,674		(16,286		)	879,857		879,857
	Total available for sale	11,190,311		436,347		(111,134		)	11,515,524		11,515,524
	Total investments in fixed maturity securities	$	11,291,631	$	451,247	$	(111,134	)	$	11,631,744	$	11,616,844
	________________
	-1	Gross unrealized losses for residential mortgage-backed securities include $1,020,000 and $1,961,000 as of September 30, 2014 and December 31, 2013, respectively, related to the non-credit portion of other-than-temporary impairments (“OTTI”) recognized in accumulated other comprehensive income.
	The amortized cost and fair value of fixed maturity securities at September 30, 2014, by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because certain issuers may have the right to call or prepay obligations.
	(In thousands)	Amortized		Fair Value
		Cost
	Due in one year or less	$	889,062	$	900,273
	Due after one year through five years	4,052,836		4,268,705
	Due after five years through ten years	3,105,077		3,288,731
	Due after ten years	2,523,971		2,634,261
	Mortgage-backed securities	1,310,361		1,326,046
	Total	$	11,881,307	$	12,418,016
	At September 30, 2014, there were no investments, other than investments in United States government and government agency securities, which exceeded 10% of common stockholders’ equity.

Investments_in_Equity_Securiti

Investments in Equity Securities (Equity securities available for sale)	9 Months Ended
	Sep. 30, 2014
Equity securities available for sale	'
Schedule of Available-for-sale Securities [Line Items]	'
Investments in Equity Securities	'
	Investments in Equity Securities
	At September 30, 2014 and December 31, 2013, investments in equity securities were as follows:
	(In thousands)	Cost		Gross Unrealized					Fair		Carrying
				Gains		Losses			Value		Value
	September 30, 2014
	Common stocks	$	68,762	$	11,742	$	(531	)	$	79,973	$	79,973
	Preferred stocks	92,767		52,463		(3,179		)	142,051		142,051
	Total	$	161,529	$	64,205	$	(3,710	)	$	222,024	$	222,024
	December 31, 2013
	Common stocks	$	118,536	$	42,239	$	—		$	160,775	$	160,775
	Preferred stocks	85,091		43,791		(6,319		)	122,563		122,563
	Total	$	203,627	$	86,030	$	(6,319	)	$	283,338	$	283,338

Arbitrage_Trading_Account_Arbi

Arbitrage Trading Account Arbitrage Trading Account	9 Months Ended
	Sep. 30, 2014
Investments, Debt and Equity Securities [Abstract]	'
Arbitrage Trading Account	'
	Arbitrage Trading Account
	At September 30, 2014 and December 31, 2013, the carrying value of the arbitrage trading account was $918 million and $522 million, respectively. The primary focus of the trading account is merger arbitrage. Merger arbitrage is the business of investing in the securities of publicly held companies which are the targets in announced tender offers and mergers. Arbitrage investing differs from other types of investing in its focus on transactions and events believed likely to bring about a change in value over a relatively short time period (usually four months or less). The Company believes that this makes merger arbitrage investments less vulnerable to changes in general financial market conditions.

Net_Investment_Income_Net_Inve

Net Investment Income Net Investment Income	9 Months Ended
	Sep. 30, 2014
Income Statement [Abstract]	'
Net Investment Income	'
	Net Investment Income
	Net investment income consists of the following:
		For the Three Months						For the Nine Months
		Ended September 30,						Ended September 30,
	(In thousands)	2014			2013			2014			2013
	Investment income earned on:
	Fixed maturity securities, including cash and cash equivalents and loans receivable	$	117,289		$	104,033		$	331,947		$	333,072
	Investment funds	59,077			5,492			135,232			45,248
	Arbitrage trading account	47			11,738			12,508			14,265
	Equity securities available for sale	1,369			3,192			5,418			9,073
	Real estate	3,042			3,086			9,207			9,343
	Gross investment income	180,824			127,541			494,312			411,001
	Investment expense	(1,599		)	(1,907		)	(7,647		)	(5,701		)
	Net investment income	$	179,225		$	125,634		$	486,665		$	405,300

Investment_Funds_Investment_Fu

Investment Funds Investment Funds	9 Months Ended
	Sep. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
Net Investment Income	'
	Investment Funds
	Investment funds consist of the following:
		Carrying Value as of				Income from Investment Funds
		September 30,		December 31,		For the Nine Months Ended September 30,
	(In thousands)	2014		2013		2014		2013
	Real estate	$	282,431	$	378,435	$	24,341	$	5,777
	Energy	159,857		155,026		18,136		25,959
	Arbitrage	286,845		271,575		15,270		3,050
	Other	290,999		262,459		77,485		10,462
	Total	$	1,020,132	$	1,067,495	$	135,232	$	45,248
	The Company's share of the earnings or losses of investment funds is generally reported on a one-quarter lag in order to facilitate the timely completion of the Company's consolidated financial statements.

Real_Estate_Real_Estate

Real Estate Real Estate	9 Months Ended
	Sep. 30, 2014
Real Estate [Abstract]	'
Real Estate	'
	Real Estate
	Investment in real estate represents directly owned property held for investment, as follows:
		Carrying Value
		September 30,		December 31,
	(In thousands)	2014		2013
	Properties in operation	$	196,884	$	283,393
	Properties under development	507,110		431,849
	Total	$	703,994	$	715,242
	Included in properties in operation are a long-term ground lease in Washington, D.C. and an office building in West Palm Beach, Florida. Properties in operation are net of accumulated depreciation and amortization of $68,000 and $17,827,000 as of September 30, 2014 and December 31, 2013, respectively. Related depreciation expense was $3,228,000 and $5,111,000 for the nine months ended September 30, 2014 and 2013, respectively. Future minimum rental income expected on operating leases relating to properties in operation is $2,820,000 in 2014, $11,360,000 in 2015, $11,379,000 in 2016, $11,420,000 in 2017, $10,750,000 in 2018 and $343,903,000 thereafter.
	The properties under development are an office building in London, a mixed-use project in Washington, D.C. and an office complex in New York City.

Loans_Receivable_Loans_Receiva

Loans Receivable Loans Receivable	9 Months Ended
	Sep. 30, 2014
Receivables [Abstract]	'
Loans Receivable	'
	Loans Receivable
	Loans receivable are as follows:
	(In thousands)	September 30, 2014			31-Dec-13
	Amortized cost:
	Real estate loans	$	259,522		$	282,357
	Commercial loans	83,778			61,226
	Total	$	343,300		$	343,583
	Fair value:
	Real estate loans	$	261,342		$	284,017
	Commercial loans	85,280			62,729
	Total	$	346,622		$	346,746
	Valuation allowance:
	Specific	$	115		$	—
	General	2,427			2,087
	Total	$	2,542		$	2,087
		For the Three Months
		Ended September 30,
		2014			2013
	Increase (decrease) in valuation allowance	$	(24	)	$	72
	Loans receivable charged off	—			—
		For the Nine Months
		Ended September 30,
		2014			2013
	Increase in valuation allowance	$	455		$	137
	Loans receivable charged off	—			—
	Loans receivable in non-accrual status as of September 30, 2014 were $15.2 million resulting from the transfer of such loans to held-for-sale. There were no loans receivable in non-accrual status as of December 31, 2013.
	The Company monitors the performance of its loans receivable and assesses the ability of the borrower to pay principal and interest based upon loan structure, underlying property values, cash flow and related financial and operating performance of the property and market conditions. Loans receivable with a potential for default are further assessed using discounted cash flow analysis and comparable cost and sales methodologies, if appropriate.
	Real estate loans are secured by commercial real estate primarily located in Arizona, California, Hawaii, Illinois, New York, North Carolina, Texas and Virginia. Real estate loans generally earn interest at floating LIBOR-based interest rates and have maturities (inclusive of extension options) through August 2025. Commercial loans are with small business owners who have secured the related financing with the assets of the business. Commercial loans generally earn interest on a fixed basis and have varying maturities not exceeding 10 years.
	The Company utilizes an internal risk rating system to assign a risk to each of its real estate loans. The loan rating system takes into consideration credit quality indicators including loan to value ratios, which compare the outstanding loan amount to the estimated value of the property, the borrower’s financial condition and performance with respect to loan terms, the Company’s position in the capital structure, and the overall leverage in the capital structure. Based on this rating system, none of the real estate loans were considered to be impaired at September 30, 2014, and accordingly, the Company determined that a specific valuation allowance was not required.

Realized_And_Unrealized_Invest

Realized And Unrealized Investment Gains (Losses)	9 Months Ended
	Sep. 30, 2014
Realized and Unrealized Investment Gains (Losses) [Abstract]	'
Realized and Unrealized Investment Gains (Losses)	'
	Realized and Unrealized Investment Gains (Losses)
	Realized and unrealized investment gains (losses) are as follows:
		For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	(In thousands)	2014			2013			2014			2013
	Realized investment gains (losses):
	Fixed maturity securities:
	Gains	$	13,803		$	19,500		$	17,263		$	39,643
	Losses	(2,208		)	(739		)	(3,727		)	(12,205		)
	Equity securities available for sale	9,729			25,158			39,310			58,489
	Investment funds	50,919			(34		)	95,675			11,003
	Real estate	15			—			85,659			—
	Other	—			(16		)	—			(34		)
	Total	72,258			43,869			234,180			96,896
	Income tax expense	(25,290		)	(15,355		)	(81,963		)	(33,914		)
	Total after-tax realized investment gains	$	46,968		$	28,514		$	152,217		$	62,982
	Change in unrealized investment gains (losses):
	Fixed maturity securities	$	10,722		$	(46,004	)	$	190,242		$	(339,384	)
	Previously impaired fixed maturity securities	188			299			941			821
	Equity securities available for sale	(27,548		)	(13,984		)	(19,215		)	(5,614		)
	Investment funds	(8,391		)	3,926			(8,317		)	(5,248		)
	Total change in unrealized investment gains (losses)	(25,029		)	(55,763		)	163,651			(349,425		)
	Income tax benefit (expense)	12,117			16,884			(55,419		)	121,296
	Noncontrolling interests	(82		)	(9		)	(119		)	(14		)
	Total after-tax unrealized gains (losses)	$	(12,994	)	$	(38,888	)	$	108,113		$	(228,143	)

Securities_In_An_Unrealized_Lo

Securities In An Unrealized Loss Position	9 Months Ended
	Sep. 30, 2014
Investments [Abstract]	'
Securities in Unrealized Loss Position	'
	Securities in an Unrealized Loss Position
	The following tables summarize all securities in an unrealized loss position at September 30, 2014 and December 31, 2013 by the length of time those securities have been continuously in an unrealized loss position:
		Less Than 12 Months						12 Months or Greater				Total
	(In thousands)	Fair Value			Gross			Fair Value		Gross		Fair Value		Gross
					Unrealized					Unrealized				Unrealized
					Losses					Losses				Losses
	September 30, 2014
	U.S. government and government agency	$	131,471		$	1,411		$	85,253	$	3,818	$	216,724	$	5,229
	State and municipal	111,019			743			175,757		4,076		286,776		4,819
	Mortgage-backed securities	182,774			1,481			295,503		12,811		478,277		14,292
	Corporate	1,068,868			3,983			269,171		13,025		1,338,039		17,008
	Foreign	82,459			3,154			120,708		10,053		203,167		13,207
	Fixed maturity securities	1,576,591			10,772			946,392		43,783		2,522,983		54,555
	Common stocks	10,813			531			—		—		10,813		531
	Preferred stocks	3,005			40			22,535		3,139		25,540		3,179
	Equity securities	13,818			571			22,535		3,139		36,353		3,710
	Total	$	1,590,409		$	11,343		$	968,927	$	46,922	$	2,559,336	$	58,265
	December 31, 2013
	U.S. government and government agency	$	260,882		$	7,927		$	2,163	$	55	$	263,045	$	7,982
	State and municipal	899,613			24,503			87,345		5,334		986,958		29,837
	Mortgage-backed securities	578,603			17,964			140,648		8,965		719,251		26,929
	Corporate	1,013,373			17,066			105,074		13,034		1,118,447		30,100
	Foreign	320,215			16,286			—		—		320,215		16,286
	Fixed maturity securities	3,072,686			83,746			335,230		27,388		3,407,916		111,134
	Common stocks	—			—			—		—		—		—
	Preferred stocks	13,291			513			19,868		5,806		33,159		6,319
	Equity securities	13,291			513			19,868		5,806		33,159		6,319
	Total	$	3,085,977		$	84,259		$	355,098	$	33,194	$	3,441,075	$	117,453
	Fixed Maturity Securities – A summary of the Company’s non-investment grade fixed maturity securities that were in an unrealized loss position at September 30, 2014 is presented in the table below.
	($ in thousands)	Number of		Aggregate			Gross
		Securities		Fair Value			Unrealized
							Loss
	Mortgage-backed securities	9		$	42,230		$	1,611
	Corporate	9		27,494			647
	Foreign	—		—			—
	Total	18		$	69,724		$	2,258
	For OTTI of fixed maturity securities that management does not intend to sell or, more likely than not, would not be required to sell, the portion of the decline in value considered to be due to credit factors is recognized in earnings and the portion of the decline in value considered to be due to non-credit factors is recognized in other comprehensive income. For the nine months ended September 30, 2014 and 2013, there were no changes in the portion of impairments recognized in earnings for those securities that have been impaired due to both credit factors and non-credit factors.
	The Company has evaluated its fixed maturity securities in an unrealized loss position and believes the unrealized losses are due primarily to temporary market and sector-related factors rather than to issuer-specific factors. None of these securities are delinquent or in default under financial covenants. Based on its assessment of these issuers, the Company expects them to continue to meet their contractual payment obligations as they become due and does not consider any of these securities to be OTTI.
	Preferred Stocks – At September 30, 2014, there were two preferred stocks in an unrealized loss position, with an aggregate fair value of $26 million and a gross unrealized loss of $3 million. Based upon management’s view of the underlying value of these securities, the Company does not consider these preferred stocks to be OTTI.

Fair_Value_Measurements_Fair_V

Fair Value Measurements Fair Value Measurements	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Disclosures	'
	Fair Value Measurements
	The Company’s fixed maturity and equity securities available for sale and its arbitrage trading account securities are carried at fair value. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for similar assets in active markets. Level 3 inputs are unobservable inputs for the asset or liability. Unobservable inputs may only be used to measure fair value to the extent that observable inputs are not available.
	Because many fixed maturity securities do not trade on a daily basis, the Company utilizes pricing models and processes, which may include benchmark curves, benchmarking of like securities, sector groupings and matrix pricing. Market inputs used to evaluate securities include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data. Quoted prices are often unavailable for recently issued securities, securities that are infrequently traded or securities that are only traded in private transactions. For publicly traded securities for which quoted prices are unavailable, the Company determines fair value based on independent broker quotations and other observable market data. For securities traded only in private negotiations, the Company determines fair value based primarily on the cost of such securities, which is adjusted to reflect prices of recent placements of securities of the same issuer, financial projections, credit quality and business developments of the issuer and other relevant information.
	The following tables present the assets and liabilities measured at fair value, on a recurring basis, as of September 30, 2014 and December 31, 2013 by level:
	(In thousands)	Total		Level 1			Level 2			Level 3
	September 30, 2014
	Assets:
	Fixed maturity securities available for sale:
	U.S. government and government agency	$	813,034	$	—		$	813,034		$	—
	State and municipal	4,180,068		—			4,180,068			—
	Mortgage-backed securities	1,298,845		—			1,298,845			—
	Corporate	5,041,702		—			5,017,702			24,000
	Foreign government	962,911		—			962,911			—
	Total fixed maturity securities available for sale	12,296,560		—			12,272,560			24,000
	Equity securities available for sale:
	Common stocks	79,973		68,852			—			11,121
	Preferred stocks	142,051		—			138,313			3,738
	Total equity securities available for sale	222,024		68,852			138,313			14,859
	Arbitrage trading account	918,223		237,310			676,896			4,017
	Total	$	13,436,807	$	306,162		$	13,087,769		$	42,876
	Liabilities:
	Securities sold but not yet purchased	$	159,537	$	159,501		$	5		$	31
	December 31, 2013
	Assets:
	Fixed maturity securities available for sale:
	U.S. government and government agency	$	884,859	$	—		$	884,859		$	—
	State and municipal	4,218,284		—			4,218,284			—
	Mortgage-backed securities	1,329,783		—			1,329,783			—
	Corporate	4,202,741		—			4,159,877			42,864
	Foreign government	879,857		—			879,857			—
	Total fixed maturity securities available for sale	11,515,524		—			11,472,660			42,864
	Equity securities available for sale:
	Common stocks	160,775		159,537			—			1,238
	Preferred stocks	122,563		—			118,811			3,752
	Total equity securities available for sale	283,338		159,537			118,811			4,990
	Arbitrage trading account	522,128		192,281			328,067			1,780
	Total	$	12,320,990	$	351,818		$	11,919,538		$	49,634
	Liabilities:
	Securities sold but not yet purchased	$	162,278	$	162,126		$	152		$	—
	There were no significant transfers between Levels 1 and 2 during the nine months ended September 30, 2014 or during the year ended December 31, 2013.
	The following tables summarize changes in Level 3 assets and liabilities for the nine months ended September 30, 2014 and for the year ended December 31, 2013:
				Gains (Losses) Included in
	(In thousands)	Beginning		Earnings			Other			Purchases		(Sales)			Maturities			Transfer in (out)			Ending
		Balance					Comprehensive														Balance
							Income
	Nine months ended September 30, 2014:
	Assets:
	Fixed maturities available for sale:
	Corporate	$	42,864	$	49		$	(1,146	)	$	84	$	(15,244	)	$	(2,607	)	$	—		$	24,000
	Total	42,864		49			(1,146		)	84		(15,244		)	(2,607		)	—			24,000
	Equity securities available for sale:
	Common stocks	1,238		—			(531		)	11,343		(929		)	—			—			11,121
	Preferred stocks	3,752		8			—			3,430		(3,452		)	—			—			3,738
	Total	4,990		8			(531		)	14,773		(4,381		)	—			—			14,859
	Arbitrage trading account	1,780		2,294			—			4,942		(14,063		)	—			9,064			4,017
	Total	$	49,634	$	2,351		$	(1,677	)	$	19,799	$	(33,688	)	$	(2,607	)	$	9,064		$	42,876
	Liabilities:
	Securities sold but not yet purchased	$	—	$	—		$	—		$	31	$	—		$	—		$	—		$	31
	Year ended December 31, 2013:
	Assets:
	Fixed maturities available for sale:
	Corporate	$	59,065	$	677		$	309		$	170	$	(4,753	)	$	(12,604	)	$	—		$	42,864
	Total	59,065		677			309			170		(4,753		)	(12,604		)	—			42,864
Equity securities available for sale:
Common stocks	1,408		—			—			—		(170		)	—			—			1,238
Preferred stocks	621		(299		)	—			3,430		—			—			—			3,752
Total	2,029		(299		)	—			3,430		(170		)	—			—			4,990
Arbitrage trading account	928		1,458			730			824		(853		)	—			(1,307		)	1,780
Total	$	62,022	$	1,836		$	1,039		$	4,424	$	(5,776	)	$	(12,604	)	$	(1,307	)	$	49,634
Liabilities:
Securities sold but not yet purchased	$	20	$	(4	)	$	—		$	4	$	(20	)	$	—		$	—		$	—
During the nine months ended September 30, 2014, two securities were transferred into Level 3 where the quoted prices were no longer available. One of these securities was sold during the second quarter of 2014. There were no significant transfers in or out of Level 3 during the year ended December 31, 2013.
Fair Value of Financial Instruments
The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments:
	September 30, 2014					December 31, 2013
(In thousands)	Carrying Value		Fair Value			Carrying Value			Fair Value
Assets:
Fixed maturity securities	$	12,397,756	$	12,418,016		$	11,616,844		$	11,631,744
Equity securities available for sale	222,024		222,024			283,338			283,338
Arbitrage trading account	918,223		918,223			522,128			522,128
Loans receivable	343,300		346,622			343,583			346,746
Cash and cash equivalents	1,342,285		1,342,285			839,738			839,738
Trading account receivables from brokers and clearing organizations	—		—			304,936			304,936
Due from broker	—		—			17,735			17,735
Liabilities:
Due to broker	58,926		58,926			8,273			8,273
Trading account payable to brokers and clearing organizations	95,681		95,681			—			—
Trading account securities sold but not yet purchased	159,537		159,537			162,278			162,278
Junior subordinated debentures	339,995		326,480			339,800			288,540
Senior notes and other debt	2,122,030		2,341,816			1,692,442			1,861,898
The estimated fair values of the Company’s fixed maturity securities, equity securities available for sale and arbitrage trading account securities are based on various valuation techniques that rely on fair value measurements as described in Note 16 above. The fair value of loans receivable are estimated by using current institutional purchaser yield requirements for loans with similar credit characteristics, which is considered a Level 2 input. The fair value of the senior notes and other debt and the junior subordinated debentures is based on spreads for similar securities, which is considered a Level 2 input.

Reinsurance_Reinsurance

Reinsurance Reinsurance	9 Months Ended
	Sep. 30, 2014
Insurance [Abstract]	'
Reinsurance [Text Block]	'
	Reinsurance
	The following is a summary of reinsurance financial information:
		For the Three Months						For the Nine Months
		Ended September 30,						Ended September 30,
	(In thousands)	2014			2013			2014			2013
	Written premiums:
	Direct	$	1,553,493		$	1,415,775		$	4,699,319		$	4,221,370
	Assumed	225,863			251,331			657,704			695,293
	Ceded	(253,974		)	(243,481		)	(815,985		)	(774,174		)
	Total net premiums written	$	1,525,382		$	1,423,625		$	4,541,038		$	4,142,489
	Earned premiums:
	Direct	$	1,505,738		$	1,351,542		$	4,336,463		$	3,893,806
	Assumed	216,889			226,530			667,566			658,063
	Ceded	(261,823		)	(249,210		)	(761,968		)	(708,373		)
	Total net premiums earned	$	1,460,804		$	1,328,862		$	4,242,061		$	3,843,496
	Ceded losses incurred	$	128,903		$	186,504		$	319,156		$	439,415
	The Company reinsures a portion of its insurance exposures in order to reduce its net liability on individual risks and catastrophe losses. The Company also cedes premiums to state assigned risk plans and captive insurance companies. Estimated amounts due from reinsurers are reported net of reserves for uncollectible reinsurance of $2 million as of September 30, 2014 and $1 million as of December 31, 2013.

Fair_Value_Of_Financial_Instru

Fair Value Of Financial Instruments Fair Value of Financial Instruments (Notes)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Disclosures	'
	Fair Value Measurements
	The Company’s fixed maturity and equity securities available for sale and its arbitrage trading account securities are carried at fair value. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” The Company utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for similar assets in active markets. Level 3 inputs are unobservable inputs for the asset or liability. Unobservable inputs may only be used to measure fair value to the extent that observable inputs are not available.
	Because many fixed maturity securities do not trade on a daily basis, the Company utilizes pricing models and processes, which may include benchmark curves, benchmarking of like securities, sector groupings and matrix pricing. Market inputs used to evaluate securities include benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data. Quoted prices are often unavailable for recently issued securities, securities that are infrequently traded or securities that are only traded in private transactions. For publicly traded securities for which quoted prices are unavailable, the Company determines fair value based on independent broker quotations and other observable market data. For securities traded only in private negotiations, the Company determines fair value based primarily on the cost of such securities, which is adjusted to reflect prices of recent placements of securities of the same issuer, financial projections, credit quality and business developments of the issuer and other relevant information.
	The following tables present the assets and liabilities measured at fair value, on a recurring basis, as of September 30, 2014 and December 31, 2013 by level:
	(In thousands)	Total		Level 1			Level 2			Level 3
	September 30, 2014
	Assets:
	Fixed maturity securities available for sale:
	U.S. government and government agency	$	813,034	$	—		$	813,034		$	—
	State and municipal	4,180,068		—			4,180,068			—
	Mortgage-backed securities	1,298,845		—			1,298,845			—
	Corporate	5,041,702		—			5,017,702			24,000
	Foreign government	962,911		—			962,911			—
	Total fixed maturity securities available for sale	12,296,560		—			12,272,560			24,000
	Equity securities available for sale:
	Common stocks	79,973		68,852			—			11,121
	Preferred stocks	142,051		—			138,313			3,738
	Total equity securities available for sale	222,024		68,852			138,313			14,859
	Arbitrage trading account	918,223		237,310			676,896			4,017
	Total	$	13,436,807	$	306,162		$	13,087,769		$	42,876
	Liabilities:
	Securities sold but not yet purchased	$	159,537	$	159,501		$	5		$	31
	December 31, 2013
	Assets:
	Fixed maturity securities available for sale:
	U.S. government and government agency	$	884,859	$	—		$	884,859		$	—
	State and municipal	4,218,284		—			4,218,284			—
	Mortgage-backed securities	1,329,783		—			1,329,783			—
	Corporate	4,202,741		—			4,159,877			42,864
	Foreign government	879,857		—			879,857			—
	Total fixed maturity securities available for sale	11,515,524		—			11,472,660			42,864
	Equity securities available for sale:
	Common stocks	160,775		159,537			—			1,238
	Preferred stocks	122,563		—			118,811			3,752
	Total equity securities available for sale	283,338		159,537			118,811			4,990
	Arbitrage trading account	522,128		192,281			328,067			1,780
	Total	$	12,320,990	$	351,818		$	11,919,538		$	49,634
	Liabilities:
	Securities sold but not yet purchased	$	162,278	$	162,126		$	152		$	—
	There were no significant transfers between Levels 1 and 2 during the nine months ended September 30, 2014 or during the year ended December 31, 2013.
	The following tables summarize changes in Level 3 assets and liabilities for the nine months ended September 30, 2014 and for the year ended December 31, 2013:
				Gains (Losses) Included in
	(In thousands)	Beginning		Earnings			Other			Purchases		(Sales)			Maturities			Transfer in (out)			Ending
		Balance					Comprehensive														Balance
							Income
	Nine months ended September 30, 2014:
	Assets:
	Fixed maturities available for sale:
	Corporate	$	42,864	$	49		$	(1,146	)	$	84	$	(15,244	)	$	(2,607	)	$	—		$	24,000
	Total	42,864		49			(1,146		)	84		(15,244		)	(2,607		)	—			24,000
	Equity securities available for sale:
	Common stocks	1,238		—			(531		)	11,343		(929		)	—			—			11,121
	Preferred stocks	3,752		8			—			3,430		(3,452		)	—			—			3,738
	Total	4,990		8			(531		)	14,773		(4,381		)	—			—			14,859
	Arbitrage trading account	1,780		2,294			—			4,942		(14,063		)	—			9,064			4,017
	Total	$	49,634	$	2,351		$	(1,677	)	$	19,799	$	(33,688	)	$	(2,607	)	$	9,064		$	42,876
	Liabilities:
	Securities sold but not yet purchased	$	—	$	—		$	—		$	31	$	—		$	—		$	—		$	31
	Year ended December 31, 2013:
	Assets:
	Fixed maturities available for sale:
	Corporate	$	59,065	$	677		$	309		$	170	$	(4,753	)	$	(12,604	)	$	—		$	42,864
	Total	59,065		677			309			170		(4,753		)	(12,604		)	—			42,864
Equity securities available for sale:
Common stocks	1,408		—			—			—		(170		)	—			—			1,238
Preferred stocks	621		(299		)	—			3,430		—			—			—			3,752
Total	2,029		(299		)	—			3,430		(170		)	—			—			4,990
Arbitrage trading account	928		1,458			730			824		(853		)	—			(1,307		)	1,780
Total	$	62,022	$	1,836		$	1,039		$	4,424	$	(5,776	)	$	(12,604	)	$	(1,307	)	$	49,634
Liabilities:
Securities sold but not yet purchased	$	20	$	(4	)	$	—		$	4	$	(20	)	$	—		$	—		$	—
During the nine months ended September 30, 2014, two securities were transferred into Level 3 where the quoted prices were no longer available. One of these securities was sold during the second quarter of 2014. There were no significant transfers in or out of Level 3 during the year ended December 31, 2013.
Fair Value of Financial Instruments
The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments:
	September 30, 2014					December 31, 2013
(In thousands)	Carrying Value		Fair Value			Carrying Value			Fair Value
Assets:
Fixed maturity securities	$	12,397,756	$	12,418,016		$	11,616,844		$	11,631,744
Equity securities available for sale	222,024		222,024			283,338			283,338
Arbitrage trading account	918,223		918,223			522,128			522,128
Loans receivable	343,300		346,622			343,583			346,746
Cash and cash equivalents	1,342,285		1,342,285			839,738			839,738
Trading account receivables from brokers and clearing organizations	—		—			304,936			304,936
Due from broker	—		—			17,735			17,735
Liabilities:
Due to broker	58,926		58,926			8,273			8,273
Trading account payable to brokers and clearing organizations	95,681		95,681			—			—
Trading account securities sold but not yet purchased	159,537		159,537			162,278			162,278
Junior subordinated debentures	339,995		326,480			339,800			288,540
Senior notes and other debt	2,122,030		2,341,816			1,692,442			1,861,898
The estimated fair values of the Company’s fixed maturity securities, equity securities available for sale and arbitrage trading account securities are based on various valuation techniques that rely on fair value measurements as described in Note 16 above. The fair value of loans receivable are estimated by using current institutional purchaser yield requirements for loans with similar credit characteristics, which is considered a Level 2 input. The fair value of the senior notes and other debt and the junior subordinated debentures is based on spreads for similar securities, which is considered a Level 2 input.

Restricted_Stock_Units_Restric

Restricted Stock Units Restricted Stock Units (Notes)	9 Months Ended
	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Restricted Stock Units	'
	Restricted Stock Units
	Pursuant to its stock incentive plan, the Company may issue restricted stock units (RSUs) to employees of the Company and its subsidiaries. The RSUs generally vest five years from the award date and are subject to other vesting and forfeiture provisions contained in the award agreement. RSUs are expensed pro-ratably over the vesting period. RSU expenses were $20 million and $16 million for the nine months ended September 30, 2014 and 2013, respectively. A summary of RSUs issued in the nine months ended September 30, 2014 and 2013 follows:
	($ in thousands)	Units	Fair Value
	Nine months ended September 30,
	2014	1,135,900	$	50,791
	2013	93,150	$	3,957

Litigation_and_Contingent_Liab

Litigation and Contingent Liabilities Litigation and Contingent Liabilities	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies Disclosure [Text Block]	'
	Litigation and Contingent Liabilities
	In the ordinary course of business, the Company is subject to disputes, litigation and arbitration arising from its insurance and reinsurance businesses. These matters are generally related to insurance and reinsurance claims and are considered in the establishment of loss and loss expense reserves. In addition, the Company may also become involved in legal actions which seek extra-contractual damages, punitive damages or penalties, including claims alleging bad faith in handling of insurance claims. The Company expects its ultimate liability with respect to such matters will not be material to its financial condition. However, adverse outcomes on such matters are possible, from time to time, and could be material to the Company’s results of operations in any particular financial reporting period.

Industry_Segments

Industry Segments	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Industry Segments	'
	Business Segments
	The Company’s financial results are presented for the following reportable business segments, plus a corporate segment:
	•	Insurance-Domestic - commercial insurance business, including excess and surplus lines and admitted lines, primarily throughout the United States;
	•	Insurance-International - insurance business primarily in the United Kingdom, Continental Europe, South America, Canada, Scandinavia, and Australia; and
	•	Reinsurance-Global - reinsurance business on a facultative and treaty basis, primarily in the United States, United Kingdom, Continental Europe, Australia, and the Asia-Pacific Region.
	The accounting policies of the segments are the same as those described in the summary of significant accounting policies. Income tax expense and benefits are calculated based upon the Company’s overall effective tax rate.
	Summary financial information about the Company's business segments is presented in the following tables:
		Revenues
	(In thousands)	Earned		Investment		Other		Total		Pre-Tax			Net
		Premiums		Income						Income			Income
										(Loss)			(Loss) to Common Stockholders
	Three months ended September 30, 2014:
	Insurance-Domestic	$	1,093,554	$	125,792	$	26,408	$	1,245,754	$	228,359		$	154,718
	Insurance-International	205,529		19,957		—		225,486		12,603			9,217
	Reinsurance-Global	161,721		26,916		—		188,637		29,005			20,207
	Corporate and eliminations (1)	—		6,560		101,910		108,470		(63,772		)	(42,571		)
	Net investment gains	—		—		72,258		72,258		72,258			46,968
	Total	$	1,460,804	$	179,225	$	200,576	$	1,840,605	$	278,453		$	188,539
	Three months ended September 30, 2013:
	Insurance-Domestic	$	958,994	$	94,071	$	26,125	$	1,079,190	$	172,177		$	118,183
	Insurance-International	189,054		11,151		—		200,205		16,129			11,225
	Reinsurance-Global	180,814		20,121		—		200,935		24,559			17,300
	Corporate and eliminations (1)	—		291		109,634		109,925		(58,501		)	(38,248		)
	Net investment gains	—		—		43,869		43,869		43,869			28,514
	Total	$	1,328,862	$	125,634	$	179,628	$	1,634,124	$	198,233		$	136,974
	Nine months ended September 30, 2014:
	Insurance-Domestic	$	3,138,806	$	347,002	$	82,159	$	3,567,967	$	607,399		$	414,588
	Insurance-International	592,721		47,885		—		640,606		41,860			29,938
	Reinsurance-Global	510,534		72,102		—		582,636		86,945			60,624
	Corporate and eliminations (1)	—		19,676		299,435		319,111		(180,892		)	(119,194		)
	Net investment gains	—		—		234,180		234,180		234,180			152,217
	Total	$	4,242,061	$	486,665	$	615,774	$	5,344,500	$	789,492		$	538,173
	Nine months ended September 30, 2013:
	Insurance-Domestic	$	2,769,369	$	299,430	$	80,513	$	3,149,312	$	465,861		$	324,069
	Insurance-International	540,365		36,383		—		576,748		51,094			35,794
	Reinsurance-Global	533,762		65,656		—		599,418		87,252			61,375
	Corporate and eliminations (1)	—		3,831		285,650		289,481		(183,941		)	(114,674		)
	Net investment gains	—		—		96,896		96,896		96,896			62,982
	Total	$	3,843,496	$	405,300	$	463,059	$	4,711,855	$	517,162		$	369,546
	(1) Corporate and eliminations represent corporate revenues and expenses that are not allocated to business segments.
	Identifiable assets by segment are as follows:
	(In thousands)	September 30, 2014		31-Dec-13
	Insurance-Domestic	$	16,074,387	$	15,247,807
	Insurance-International	1,915,322		1,516,310
	Reinsurance-Global	2,801,268		3,103,193
	Corporate and eliminations	1,306,620		684,486
	Total	$	22,097,597	$	20,551,796
	Net premiums earned by major line of business are as follows:
		For the Three Months				For the Nine Months
		Ended September 30,				Ended September 30,
	(In thousands)	2014		2013		2014		2013
	Insurance-Domestic:
	Other liability	$	368,818	$	314,878	$	1,070,525	$	917,910
	Workers’ compensation	291,297		252,220		824,541		722,422
	Short-tail lines	222,561		199,181		642,833		570,868
	Commercial automobile	134,197		125,942		385,667		361,964
	Professional liability	76,681		66,773		215,240		196,205
	Total	1,093,554		958,994		3,138,806		2,769,369
	Insurance-International:
	Other liability	27,705		18,457		70,036		48,745
	Workers’ compensation	18,012		20,847		52,578		65,482
	Short-tail lines	100,417		92,213		303,119		248,637
	Commercial automobile	29,076		30,898		86,318		97,929
Professional liability	30,319		26,639		80,670		79,572
Total	205,529		189,054		592,721		540,365
Reinsurance-Global:
Casualty	122,741		128,127		372,894		371,571
Property	38,980		52,687		137,640		162,191
Total	161,721		180,814		510,534		533,762
Total	$	1,460,804	$	1,328,862	$	4,242,061	$	3,843,496

Per_Share_Data_Tables

Per Share Data (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Schedule of Weighted Average Number of Shares [Table Text Block]	'
	The weighted average number of common shares used in the computation of basic and diluted earnings per share was as follows:
		For the Three Months		For the Nine Months
		Ended September 30,		Ended September 30,
	(In thousands)	2014	2013	2014	2013
	Basic	127,165	135,268	128,225	135,726
	Diluted	133,001	140,758	133,886	141,095

Acquistions_Acquisitions_Table

Acquistions Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Summary of fair value of net assets acquired and liabilities assumed	'
	The following table summarizes the estimated fair value of net assets acquired and liabilities assumed for business combinations completed in 2014 and 2013:
		September 30,			December 31,
	(In thousands)	2014			2013
	Cash and cash equivalents	$	17,456		$	3,911
	Real estate, furniture and equipment	669			898
	Goodwill and other intangibles assets	77,967			64,464
	Premium and service fee receivable	20,178			—
	Other assets	—			60,661
	Total assets acquired	116,270			129,934
	Debt	—			(27,612		)
	Other liabilities assumed	(33,391		)	(17,076		)
	Net assets acquired	$	82,879		$	85,246

Statements_of_Comprehensive_In1

Statements of Comprehensive Income (Loss) Statements of Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Components of changes in accumulated other comprehensive income (loss)	'
	The following table presents the components of the changes in accumulated other comprehensive income (loss) ("AOCI"):
	(In thousands)	Unrealized Investment Gains (Losses)				Currency Translation Adjustments			Net Pension Asset				Accumulated Other Comprehensive Income (Loss)
	As of and for the nine months ended September 30, 2014:
	Changes in AOCI
	Beginning of period	$	256,566			$	(60,524	)	$	(6,651	)		$	189,391
	Other comprehensive income (loss) before reclassifications	143,388				(28,590		)	—				114,798
	Amounts reclassified from AOCI	(35,156		)		—			4,631				(30,525		)
	Other comprehensive income (loss)	108,232				(28,590		)	4,631				84,273
	Unrealized investment gain (loss) related to non-controlling interest	(119		)		—			—				(119		)
	End of period	$	364,679			$	(89,114	)	$	(2,020	)		$	273,545
	Amounts reclassified from AOCI
	Pre-tax	$	(54,086	)	-1	$	—		$	7,125		-2	$	(46,961	)
	Tax effect (3)	18,930				—			(2,494		)		16,436
	After-tax amounts reclassified	$	(35,156	)		$	—		$	4,631			$	(30,525	)
	Other comprehensive income (loss)
	Pre-tax	$	163,651			$	(28,590	)	$	7,125			$	142,186
	Tax effect	(55,419		)		—			(2,494		)		(57,913		)
	Other comprehensive income (loss)	$	108,232			$	(28,590	)	$	4,631			$	84,273
	As of and for the three months ended September 30, 2014:
	Changes in AOCI
	Beginning of period	$	377,673			$	(39,734	)	$	(4,040	)		$	333,899
	Other comprehensive income (loss) before reclassifications	3,099				(49,380		)	—				(46,281		)
	Amounts reclassified from AOCI	(16,011		)		—			2,020				(13,991		)
	Other comprehensive income (loss)	(12,912		)		(49,380		)	2,020				(60,272		)
	Unrealized investment gain (loss) related to non-controlling interest	(82		)		—			—				(82		)
	End of period	$	364,679			$	(89,114	)	$	(2,020	)		$	273,545
	Amounts reclassified from AOCI
	Pre-tax	$	(24,632	)	-1	$	—		$	3,108		-2	$	(21,524	)
	Tax effect (3)	8,621				—			(1,088		)		7,533
	After-tax amounts reclassified	$	(16,011	)		$	—		$	2,020			$	(13,991	)
	Other comprehensive income (loss)
	Pre-tax	$	(25,029	)		$	(49,380	)	$	3,108			$	(71,301	)
	Tax effect	12,117				—			(1,088		)		11,029
	Other comprehensive income (loss)	$	(12,912	)		$	(49,380	)	$	2,020			$	(60,272	)
		Unrealized Investment Gains (Losses)				Currency Translation Adjustments			Net Pension Asset				Accumulated Other Comprehensive Income (Loss)
	(In thousands)
	As of and for the nine months ended September 30, 2013:
	Changes in AOCI
	Beginning of period	$	517,658			$	(36,676	)	$	(15,351	)		$	465,631
	Other comprehensive income (loss) before reclassifications	(172,276		)		(25,451		)	—				(197,727		)
	Amounts reclassified from AOCI	(55,853		)		—			5,442				(50,411		)
	Other comprehensive income (loss)	(228,129		)		(25,451		)	5,442				(248,138		)
	Unrealized investment gain related to non-controlling interest	(14		)		—			—				(14		)
	End of period	$	289,515			$	(62,127	)	$	(9,909	)		$	217,479
	Amounts reclassified from AOCI
	Pre-tax	$	(85,928	)	-1	$	—		$	8,372		-2	$	(77,556	)
	Tax effect (3)	30,075				—			(2,930		)		27,145
	After-tax amounts reclassified	$	(55,853	)		$	—		$	5,442			$	(50,411	)
	Other comprehensive income (loss)
	Pre-tax	$	(350,968	)		$	(25,451	)	$	8,372			$	(368,047	)
	Tax effect	122,839				—			(2,930		)		119,909
	Other comprehensive income (loss)	$	(228,129	)		$	(25,451	)	$	5,442			$	(248,138	)
	As of and for the three months ended September 30, 2013:
	Changes in AOCI
	Beginning of period	$	328,403			$	(106,455	)	$	(11,723	)		$	210,225
	Other comprehensive income (loss) before reclassifications	(10,331		)		44,328			—				33,997
	Amounts reclassified from AOCI	(28,548		)		—			1,814				(26,734		)
	Other comprehensive income (loss)	(38,879		)		44,328			1,814				7,263
	Unrealized investment gain related to non-controlling interest	(9		)		—			—				(9		)
	End of period	$	289,515			$	(62,127	)	$	(9,909	)		$	217,479
	Amounts reclassified from AOCI
	Pre-tax	$	(43,920	)	-1	$	—		$	2,790		-2	$	(41,130	)
	Tax effect (3)	15,372				—			(976		)		14,396
After-tax amounts reclassified	$	(28,548	)		$	—		$	1,814			$	(26,734	)
Other comprehensive income (loss)
Pre-tax	$	(59,814	)		$	44,328		$	2,790			$	(12,696	)
Tax effect	20,935				—			(976		)		19,959
Other comprehensive income (loss)	$	(38,879	)		$	44,328		$	1,814			$	7,263
_______________
(1) Net investment gains in the consolidated statements of income.
(2) Other operating costs and expenses in the consolidated statements of income.
(3) Income tax expense in the consolidated statements of income.

Investments_In_Fixed_Maturity_1

Investments In Fixed Maturity Securities Investments in Fixed Maturity Securities (Tables)	9 Months Ended
	Sep. 30, 2014
Schedule of Marketable Securities [Line Items]	'
Amortized cost and fair value of fixed maturity securities by contractual maturity	'
	The amortized cost and fair value of fixed maturity securities at September 30, 2014, by contractual maturity, are shown below. Actual maturities may differ from contractual maturities because certain issuers may have the right to call or prepay obligations.
	(In thousands)	Amortized		Fair Value
		Cost
	Due in one year or less	$	889,062	$	900,273
	Due after one year through five years	4,052,836		4,268,705
	Due after five years through ten years	3,105,077		3,288,731
	Due after ten years	2,523,971		2,634,261
	Mortgage-backed securities	1,310,361		1,326,046
	Total	$	11,881,307	$	12,418,016
Debt Securities [Member]	'
Schedule of Marketable Securities [Line Items]	'
Schedule of investments in fixed maturity securities	'
	At September 30, 2014 and December 31, 2013, investments in fixed maturity securities were as follows:
	(In thousands)	Amortized		Gross Unrealized					Fair		Carrying
		Cost		Gains		Losses			Value		Value
	September 30, 2014
	Held to maturity:
	State and municipal	$	71,897	$	16,991	$	—		$	88,888	$	71,897
	Residential mortgage-backed	24,300		2,901		—			27,201		24,300
	Corporate	4,999		368		—			5,367		4,999
	Total held to maturity	101,196		20,260		—			121,456		101,196
	Available for sale:
	U.S. government and government agency	787,967		30,296		(5,229		)	813,034		813,034
	State and municipal	3,958,141		226,746		(4,819		)	4,180,068		4,180,068
	Mortgage-backed securities:
	Residential (1)	1,209,068		26,100		(14,209		)	1,220,959		1,220,959
	Commercial	76,993		976		(83		)	77,886		77,886
	Corporate	4,866,983		191,727		(17,008		)	5,041,702		5,041,702
	Foreign	880,959		95,159		(13,207		)	962,911		962,911
	Total available for sale	11,780,111		571,004		(54,555		)	12,296,560		12,296,560
	Total investments in fixed maturity securities	$	11,881,307	$	591,264	$	(54,555	)	$	12,418,016	$	12,397,756
	December 31, 2013
	Held to maturity:
	State and municipal	$	68,929	$	11,172	$	—		$	80,101	$	68,929
	Residential mortgage-backed	27,393		3,311		—			30,704		27,393
	Corporate	4,998		417		—			5,415		4,998
	Total held to maturity	101,320		14,900		—			116,220		101,320
	Available for sale:
	U.S. government and government agency	858,319		34,522		(7,982		)	884,859		884,859
	State and municipal	4,085,791		162,330		(29,837		)	4,218,284		4,218,284
	Mortgage-backed securities:
	Residential (1)	1,248,693		25,895		(25,941		)	1,248,647		1,248,647
	Commercial	76,454		5,670		(988		)	81,136		81,136
	Corporate	4,076,585		156,256		(30,100		)	4,202,741		4,202,741
	Foreign	844,469		51,674		(16,286		)	879,857		879,857
	Total available for sale	11,190,311		436,347		(111,134		)	11,515,524		11,515,524
	Total investments in fixed maturity securities	$	11,291,631	$	451,247	$	(111,134	)	$	11,631,744	$	11,616,844
	________________
	-1	Gross unrealized losses for residential mortgage-backed securities include $1,020,000 and $1,961,000 as of September 30, 2014 and December 31, 2013, respectively, related to the non-credit portion of other-than-temporary impairments (“OTTI”) recognized in accumulated other comprehensive income.

Investments_in_Equity_Securiti1

Investments in Equity Securities Investments in Equity Securities (Tables) (Equity securities available for sale)	9 Months Ended
	Sep. 30, 2014
Equity securities available for sale	'
Schedule of Available-for-sale Securities [Line Items]	'
Schedule of Investments in Equity Securities	'
	At September 30, 2014 and December 31, 2013, investments in equity securities were as follows:
	(In thousands)	Cost		Gross Unrealized					Fair		Carrying
				Gains		Losses			Value		Value
	September 30, 2014
	Common stocks	$	68,762	$	11,742	$	(531	)	$	79,973	$	79,973
	Preferred stocks	92,767		52,463		(3,179		)	142,051		142,051
	Total	$	161,529	$	64,205	$	(3,710	)	$	222,024	$	222,024
	December 31, 2013
	Common stocks	$	118,536	$	42,239	$	—		$	160,775	$	160,775
	Preferred stocks	85,091		43,791		(6,319		)	122,563		122,563
	Total	$	203,627	$	86,030	$	(6,319	)	$	283,338	$	283,338

Net_Investment_Income_Tables

Net Investment Income (Tables)	9 Months Ended
	Sep. 30, 2014
Net Investment Income [Abstract]	'
Schedule of Net Investment Income	'
	Net investment income consists of the following:
		For the Three Months						For the Nine Months
		Ended September 30,						Ended September 30,
	(In thousands)	2014			2013			2014			2013
	Investment income earned on:
	Fixed maturity securities, including cash and cash equivalents and loans receivable	$	117,289		$	104,033		$	331,947		$	333,072
	Investment funds	59,077			5,492			135,232			45,248
	Arbitrage trading account	47			11,738			12,508			14,265
	Equity securities available for sale	1,369			3,192			5,418			9,073
	Real estate	3,042			3,086			9,207			9,343
	Gross investment income	180,824			127,541			494,312			411,001
	Investment expense	(1,599		)	(1,907		)	(7,647		)	(5,701		)
	Net investment income	$	179,225		$	125,634		$	486,665		$	405,300

Investment_Funds_Investment_Fu1

Investment Funds Investment Funds (Tables)	9 Months Ended
	Sep. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
Schedule of Net Investment Funds	'
	Investment funds consist of the following:
		Carrying Value as of				Income from Investment Funds
		September 30,		December 31,		For the Nine Months Ended September 30,
	(In thousands)	2014		2013		2014		2013
	Real estate	$	282,431	$	378,435	$	24,341	$	5,777
	Energy	159,857		155,026		18,136		25,959
	Arbitrage	286,845		271,575		15,270		3,050
	Other	290,999		262,459		77,485		10,462
	Total	$	1,020,132	$	1,067,495	$	135,232	$	45,248

Real_Estate_Real_Estate_Tables

Real Estate Real Estate (Tables)	9 Months Ended
	Sep. 30, 2014
Real Estate [Abstract]	'
Schedule of Real Estate Investments	'
	Investment in real estate represents directly owned property held for investment, as follows:
		Carrying Value
		September 30,		December 31,
	(In thousands)	2014		2013
	Properties in operation	$	196,884	$	283,393
	Properties under development	507,110		431,849
	Total	$	703,994	$	715,242

Loans_Receivable_Loans_Receiva1

Loans Receivable Loans Receivable (Tables)	9 Months Ended
	Sep. 30, 2014
Receivables [Abstract]	'
Schedule of Loans Receivable	'
	Loans receivable are as follows:
	(In thousands)	September 30, 2014			31-Dec-13
	Amortized cost:
	Real estate loans	$	259,522		$	282,357
	Commercial loans	83,778			61,226
	Total	$	343,300		$	343,583
	Fair value:
	Real estate loans	$	261,342		$	284,017
	Commercial loans	85,280			62,729
	Total	$	346,622		$	346,746
	Valuation allowance:
	Specific	$	115		$	—
	General	2,427			2,087
	Total	$	2,542		$	2,087
		For the Three Months
		Ended September 30,
		2014			2013
	Increase (decrease) in valuation allowance	$	(24	)	$	72
	Loans receivable charged off	—			—
		For the Nine Months
		Ended September 30,
		2014			2013
	Increase in valuation allowance	$	455		$	137
	Loans receivable charged off	—			—

Realized_And_Unrealized_Invest1

Realized And Unrealized Investment Gains (Losses) (Tables)	9 Months Ended
	Sep. 30, 2014
Realized and Unrealized Investment Gains (Losses) [Abstract]	'
Realized and Unrealized Investment Gains (Losses)	'
	Realized and unrealized investment gains (losses) are as follows:
		For the Three Months Ended September 30,						For the Nine Months Ended September 30,
	(In thousands)	2014			2013			2014			2013
	Realized investment gains (losses):
	Fixed maturity securities:
	Gains	$	13,803		$	19,500		$	17,263		$	39,643
	Losses	(2,208		)	(739		)	(3,727		)	(12,205		)
	Equity securities available for sale	9,729			25,158			39,310			58,489
	Investment funds	50,919			(34		)	95,675			11,003
	Real estate	15			—			85,659			—
	Other	—			(16		)	—			(34		)
	Total	72,258			43,869			234,180			96,896
	Income tax expense	(25,290		)	(15,355		)	(81,963		)	(33,914		)
	Total after-tax realized investment gains	$	46,968		$	28,514		$	152,217		$	62,982
Unrealized Gain (Loss) on Investments	'
	Change in unrealized investment gains (losses):
	Fixed maturity securities	$	10,722		$	(46,004	)	$	190,242		$	(339,384	)
	Previously impaired fixed maturity securities	188			299			941			821
	Equity securities available for sale	(27,548		)	(13,984		)	(19,215		)	(5,614		)
	Investment funds	(8,391		)	3,926			(8,317		)	(5,248		)
	Total change in unrealized investment gains (losses)	(25,029		)	(55,763		)	163,651			(349,425		)
	Income tax benefit (expense)	12,117			16,884			(55,419		)	121,296
	Noncontrolling interests	(82		)	(9		)	(119		)	(14		)
	Total after-tax unrealized gains (losses)	$	(12,994	)	$	(38,888	)	$	108,113		$	(228,143	)

Securities_In_An_Unrealized_Lo1

Securities In An Unrealized Loss Position Securities In An Unrealized Loss Position (Tables)	9 Months Ended
	Sep. 30, 2014
Statement of Financial Position [Abstract]	'
Securities in an unrealized loss position	'
	The following tables summarize all securities in an unrealized loss position at September 30, 2014 and December 31, 2013 by the length of time those securities have been continuously in an unrealized loss position:
		Less Than 12 Months						12 Months or Greater				Total
	(In thousands)	Fair Value			Gross			Fair Value		Gross		Fair Value		Gross
					Unrealized					Unrealized				Unrealized
					Losses					Losses				Losses
	September 30, 2014
	U.S. government and government agency	$	131,471		$	1,411		$	85,253	$	3,818	$	216,724	$	5,229
	State and municipal	111,019			743			175,757		4,076		286,776		4,819
	Mortgage-backed securities	182,774			1,481			295,503		12,811		478,277		14,292
	Corporate	1,068,868			3,983			269,171		13,025		1,338,039		17,008
	Foreign	82,459			3,154			120,708		10,053		203,167		13,207
	Fixed maturity securities	1,576,591			10,772			946,392		43,783		2,522,983		54,555
	Common stocks	10,813			531			—		—		10,813		531
	Preferred stocks	3,005			40			22,535		3,139		25,540		3,179
	Equity securities	13,818			571			22,535		3,139		36,353		3,710
	Total	$	1,590,409		$	11,343		$	968,927	$	46,922	$	2,559,336	$	58,265
	December 31, 2013
	U.S. government and government agency	$	260,882		$	7,927		$	2,163	$	55	$	263,045	$	7,982
	State and municipal	899,613			24,503			87,345		5,334		986,958		29,837
	Mortgage-backed securities	578,603			17,964			140,648		8,965		719,251		26,929
	Corporate	1,013,373			17,066			105,074		13,034		1,118,447		30,100
	Foreign	320,215			16,286			—		—		320,215		16,286
	Fixed maturity securities	3,072,686			83,746			335,230		27,388		3,407,916		111,134
	Common stocks	—			—			—		—		—		—
	Preferred stocks	13,291			513			19,868		5,806		33,159		6,319
	Equity securities	13,291			513			19,868		5,806		33,159		6,319
	Total	$	3,085,977		$	84,259		$	355,098	$	33,194	$	3,441,075	$	117,453
Non-Investment Grade Fixed Maturity Securities	'
	Fixed Maturity Securities – A summary of the Company’s non-investment grade fixed maturity securities that were in an unrealized loss position at September 30, 2014 is presented in the table below.
	($ in thousands)	Number of		Aggregate			Gross
		Securities		Fair Value			Unrealized
							Loss
	Mortgage-backed securities	9		$	42,230		$	1,611
	Corporate	9		27,494			647
	Foreign	—		—			—
	Total	18		$	69,724		$	2,258

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Assets And Liabilities Measured At Fair value, On A Recurring Basis	'
	The following tables present the assets and liabilities measured at fair value, on a recurring basis, as of September 30, 2014 and December 31, 2013 by level:
	(In thousands)	Total		Level 1			Level 2			Level 3
	September 30, 2014
	Assets:
	Fixed maturity securities available for sale:
	U.S. government and government agency	$	813,034	$	—		$	813,034		$	—
	State and municipal	4,180,068		—			4,180,068			—
	Mortgage-backed securities	1,298,845		—			1,298,845			—
	Corporate	5,041,702		—			5,017,702			24,000
	Foreign government	962,911		—			962,911			—
	Total fixed maturity securities available for sale	12,296,560		—			12,272,560			24,000
	Equity securities available for sale:
	Common stocks	79,973		68,852			—			11,121
	Preferred stocks	142,051		—			138,313			3,738
	Total equity securities available for sale	222,024		68,852			138,313			14,859
	Arbitrage trading account	918,223		237,310			676,896			4,017
	Total	$	13,436,807	$	306,162		$	13,087,769		$	42,876
	Liabilities:
	Securities sold but not yet purchased	$	159,537	$	159,501		$	5		$	31
	December 31, 2013
	Assets:
	Fixed maturity securities available for sale:
	U.S. government and government agency	$	884,859	$	—		$	884,859		$	—
	State and municipal	4,218,284		—			4,218,284			—
	Mortgage-backed securities	1,329,783		—			1,329,783			—
	Corporate	4,202,741		—			4,159,877			42,864
	Foreign government	879,857		—			879,857			—
	Total fixed maturity securities available for sale	11,515,524		—			11,472,660			42,864
	Equity securities available for sale:
	Common stocks	160,775		159,537			—			1,238
	Preferred stocks	122,563		—			118,811			3,752
	Total equity securities available for sale	283,338		159,537			118,811			4,990
	Arbitrage trading account	522,128		192,281			328,067			1,780
	Total	$	12,320,990	$	351,818		$	11,919,538		$	49,634
	Liabilities:
	Securities sold but not yet purchased	$	162,278	$	162,126		$	152		$	—
Summarize Changes In Level 3 Assets	'
	The following tables summarize changes in Level 3 assets and liabilities for the nine months ended September 30, 2014 and for the year ended December 31, 2013:
				Gains (Losses) Included in
	(In thousands)	Beginning		Earnings			Other			Purchases		(Sales)			Maturities			Transfer in (out)			Ending
		Balance					Comprehensive														Balance
							Income
	Nine months ended September 30, 2014:
	Assets:
	Fixed maturities available for sale:
	Corporate	$	42,864	$	49		$	(1,146	)	$	84	$	(15,244	)	$	(2,607	)	$	—		$	24,000
	Total	42,864		49			(1,146		)	84		(15,244		)	(2,607		)	—			24,000
	Equity securities available for sale:
	Common stocks	1,238		—			(531		)	11,343		(929		)	—			—			11,121
	Preferred stocks	3,752		8			—			3,430		(3,452		)	—			—			3,738
	Total	4,990		8			(531		)	14,773		(4,381		)	—			—			14,859
	Arbitrage trading account	1,780		2,294			—			4,942		(14,063		)	—			9,064			4,017
	Total	$	49,634	$	2,351		$	(1,677	)	$	19,799	$	(33,688	)	$	(2,607	)	$	9,064		$	42,876
	Liabilities:
	Securities sold but not yet purchased	$	—	$	—		$	—		$	31	$	—		$	—		$	—		$	31
	Year ended December 31, 2013:
	Assets:
	Fixed maturities available for sale:
	Corporate	$	59,065	$	677		$	309		$	170	$	(4,753	)	$	(12,604	)	$	—		$	42,864
	Total	59,065		677			309			170		(4,753		)	(12,604		)	—			42,864
	Equity securities available for sale:
	Common stocks	1,408		—			—			—		(170		)	—			—			1,238
	Preferred stocks	621		(299		)	—			3,430		—			—			—			3,752
	Total	2,029		(299		)	—			3,430		(170		)	—			—			4,990
	Arbitrage trading account	928		1,458			730			824		(853		)	—			(1,307		)	1,780
	Total	$	62,022	$	1,836		$	1,039		$	4,424	$	(5,776	)	$	(12,604	)	$	(1,307	)	$	49,634
	Liabilities:
	Securities sold but not yet purchased	$	20	$	(4	)	$	—		$	4	$	(20	)	$	—		$	—		$	—

Reinsurance_Tables

Reinsurance (Tables)	9 Months Ended
	Sep. 30, 2014
Reinsurance Disclosures [Abstract]	'
Reinsurance Financial Information	'
	The following is a summary of reinsurance financial information:
		For the Three Months						For the Nine Months
		Ended September 30,						Ended September 30,
	(In thousands)	2014			2013			2014			2013
	Written premiums:
	Direct	$	1,553,493		$	1,415,775		$	4,699,319		$	4,221,370
	Assumed	225,863			251,331			657,704			695,293
	Ceded	(253,974		)	(243,481		)	(815,985		)	(774,174		)
	Total net premiums written	$	1,525,382		$	1,423,625		$	4,541,038		$	4,142,489
	Earned premiums:
	Direct	$	1,505,738		$	1,351,542		$	4,336,463		$	3,893,806
	Assumed	216,889			226,530			667,566			658,063
	Ceded	(261,823		)	(249,210		)	(761,968		)	(708,373		)
	Total net premiums earned	$	1,460,804		$	1,328,862		$	4,242,061		$	3,843,496
	Ceded losses incurred	$	128,903		$	186,504		$	319,156		$	439,415

Recovered_Sheet1

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Carrying Amounts And Estimated Fair Values Of Financial Instruments	'
	The following table presents the carrying amounts and estimated fair values of the Company’s financial instruments:
		September 30, 2014				December 31, 2013
	(In thousands)	Carrying Value		Fair Value		Carrying Value		Fair Value
	Assets:
	Fixed maturity securities	$	12,397,756	$	12,418,016	$	11,616,844	$	11,631,744
	Equity securities available for sale	222,024		222,024		283,338		283,338
	Arbitrage trading account	918,223		918,223		522,128		522,128
	Loans receivable	343,300		346,622		343,583		346,746
	Cash and cash equivalents	1,342,285		1,342,285		839,738		839,738
	Trading account receivables from brokers and clearing organizations	—		—		304,936		304,936
	Due from broker	—		—		17,735		17,735
	Liabilities:
	Due to broker	58,926		58,926		8,273		8,273
	Trading account payable to brokers and clearing organizations	95,681		95,681		—		—
	Trading account securities sold but not yet purchased	159,537		159,537		162,278		162,278
	Junior subordinated debentures	339,995		326,480		339,800		288,540
	Senior notes and other debt	2,122,030		2,341,816		1,692,442		1,861,898

Restricted_Stock_Units_Tables

Restricted Stock Units (Tables)	9 Months Ended
	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Summary Of Restricted Stock Units Issued	'
	A summary of RSUs issued in the nine months ended September 30, 2014 and 2013 follows:
	($ in thousands)	Units	Fair Value
	Nine months ended September 30,
	2014	1,135,900	$	50,791
	2013	93,150	$	3,957

Industry_Segments_Tables

Industry Segments (Tables)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Financial Information Of Company Operating Segments	'
		Revenues
	(In thousands)	Earned		Investment		Other		Total		Pre-Tax			Net
		Premiums		Income						Income			Income
										(Loss)			(Loss) to Common Stockholders
	Three months ended September 30, 2014:
	Insurance-Domestic	$	1,093,554	$	125,792	$	26,408	$	1,245,754	$	228,359		$	154,718
	Insurance-International	205,529		19,957		—		225,486		12,603			9,217
	Reinsurance-Global	161,721		26,916		—		188,637		29,005			20,207
	Corporate and eliminations (1)	—		6,560		101,910		108,470		(63,772		)	(42,571		)
	Net investment gains	—		—		72,258		72,258		72,258			46,968
	Total	$	1,460,804	$	179,225	$	200,576	$	1,840,605	$	278,453		$	188,539
	Three months ended September 30, 2013:
	Insurance-Domestic	$	958,994	$	94,071	$	26,125	$	1,079,190	$	172,177		$	118,183
	Insurance-International	189,054		11,151		—		200,205		16,129			11,225
	Reinsurance-Global	180,814		20,121		—		200,935		24,559			17,300
	Corporate and eliminations (1)	—		291		109,634		109,925		(58,501		)	(38,248		)
	Net investment gains	—		—		43,869		43,869		43,869			28,514
	Total	$	1,328,862	$	125,634	$	179,628	$	1,634,124	$	198,233		$	136,974
	Nine months ended September 30, 2014:
	Insurance-Domestic	$	3,138,806	$	347,002	$	82,159	$	3,567,967	$	607,399		$	414,588
	Insurance-International	592,721		47,885		—		640,606		41,860			29,938
	Reinsurance-Global	510,534		72,102		—		582,636		86,945			60,624
	Corporate and eliminations (1)	—		19,676		299,435		319,111		(180,892		)	(119,194		)
	Net investment gains	—		—		234,180		234,180		234,180			152,217
	Total	$	4,242,061	$	486,665	$	615,774	$	5,344,500	$	789,492		$	538,173
	Nine months ended September 30, 2013:
	Insurance-Domestic	$	2,769,369	$	299,430	$	80,513	$	3,149,312	$	465,861		$	324,069
	Insurance-International	540,365		36,383		—		576,748		51,094			35,794
	Reinsurance-Global	533,762		65,656		—		599,418		87,252			61,375
	Corporate and eliminations (1)	—		3,831		285,650		289,481		(183,941		)	(114,674		)
	Net investment gains	—		—		96,896		96,896		96,896			62,982
	Total	$	3,843,496	$	405,300	$	463,059	$	4,711,855	$	517,162		$	369,546
	(1) Corporate and eliminations represent corporate revenues and expenses that are not allocated to business segments.
Identifiable Assets By Segment	'
	Identifiable assets by segment are as follows:
	(In thousands)	September 30, 2014		31-Dec-13
	Insurance-Domestic	$	16,074,387	$	15,247,807
	Insurance-International	1,915,322		1,516,310
	Reinsurance-Global	2,801,268		3,103,193
	Corporate and eliminations	1,306,620		684,486
	Total	$	22,097,597	$	20,551,796
Net Premiums Earned By Major Line Of Business	'
	Net premiums earned by major line of business are as follows:
		For the Three Months				For the Nine Months
		Ended September 30,				Ended September 30,
	(In thousands)	2014		2013		2014		2013
	Insurance-Domestic:
	Other liability	$	368,818	$	314,878	$	1,070,525	$	917,910
	Workers’ compensation	291,297		252,220		824,541		722,422
	Short-tail lines	222,561		199,181		642,833		570,868
	Commercial automobile	134,197		125,942		385,667		361,964
	Professional liability	76,681		66,773		215,240		196,205
	Total	1,093,554		958,994		3,138,806		2,769,369
	Insurance-International:
	Other liability	27,705		18,457		70,036		48,745
	Workers’ compensation	18,012		20,847		52,578		65,482
	Short-tail lines	100,417		92,213		303,119		248,637
	Commercial automobile	29,076		30,898		86,318		97,929
	Professional liability	30,319		26,639		80,670		79,572
	Total	205,529		189,054		592,721		540,365
	Reinsurance-Global:
	Casualty	122,741		128,127		372,894		371,571
	Property	38,980		52,687		137,640		162,191
	Total	161,721		180,814		510,534		533,762
	Total	$	1,460,804	$	1,328,862	$	4,242,061	$	3,843,496

General_General_Details

General General (Details)	9 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Federal Income Tax Rate	35.00%

Per_Share_Data_Weighted_Averag

Per Share Data (Weighted Average Number of Common Shares Used In the Computation of Basic and Diluted Earnings per Share) (Details)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]	'	'	'	'
Basic (shares)	127,165	135,268	128,225	135,726
Diluted (shares)	133,001	140,758	133,886	141,095

Acquistions_Acquisitions_Detai

Acquistions Acquisitions (Details) (USD $)	1 Months Ended	12 Months Ended
	Jan. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Dec. 31, 2013
Business Acquisition [Line Items]	'	'	'	'
Significant Acquisitions and Disposals, Acquisition Costs or Sale Proceeds	'	'	$16,000,000	'
Assets of Disposal Group, Including Discontinued Operation	'	'	15,000,000	'
Goodwill	'	'	103,337,000	110,146,000
Premiums and fees receivable	'	'	1,681,674,000	1,557,480,000
After Market Original Equipment Manufacturer	'	'	'	'
Business Acquisition [Line Items]	'	'	'	'
Business Acquisition, Transaction Costs	'	'	83,000,000	'
Cash and cash equivalents	'	'	17,456,000	3,911,000
Real estate, furniture and equipment	'	'	669,000	898,000
Goodwill and other intangibles assets	'	'	77,967,000	64,464,000
Premiums and fees receivable	'	'	20,178,000	0
Other assets	'	'	0	60,661,000
Total assets acquired	'	'	116,270,000	129,934,000
Debt	'	'	0	-27,612,000
Other liabilities assumed	'	'	-33,391,000	-17,076,000
Net assets acquired	'	'	82,879,000	85,246,000
Business Acquisition, Percentage of Voting Interests Acquired	51.00%	49.00%	'	'
Business Combination, Consideration Transferred	$43,000,000	$43,000,000	'	'

Acquistions_Intangibles_Detail

Acquistions Intangibles (Details) (After Market Original Equipment Manufacturer, USD $)	1 Months Ended	9 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Jan. 31, 2013	Sep. 30, 2014	Dec. 31, 2012
Business Acquisition [Line Items]	'	'	'
Percentage acquired	51.00%	'	49.00%
Purchase amount	$43	'	$43
Acquired Indefinite-lived Intangible Assets	'	$3	'
Minimum	'	'	'
Business Acquisition [Line Items]	'	'	'
Amortization of Acquired Intangible Assets	'	'2 years	'
Maximum	'	'	'
Business Acquisition [Line Items]	'	'	'
Amortization of Acquired Intangible Assets	'	'15 years	'

Statements_of_Comprehensive_In2

Statements of Comprehensive Income (Loss) Statements of Comprehensive Income (Loss) (Details) (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]	'		'		'		'		'	'
Accumulated Other Comprehensive Income (Loss), Beginning of Period	'		'		$189,391		'		'	'
Other comprehensive income (loss)	-60,272		7,263		84,273		-248,138		'	'
Accumulated Other Comprehensive Income (Loss), End of Period	273,545		'		273,545		'		'	'
Net investment gains	72,258		43,869		234,180		96,896		'	'
Income before income taxes	278,453		198,233		789,492		517,162		'	'
Income before taxes	544,303		504,096		1,593,619		1,479,986		'	'
Tax effect	-89,662		-60,045		-250,840		-147,249		'	'
After-tax amounts reclassified	188,791		138,188		538,652		369,913		'	'
Unrealized investment gains, pre-tax	-25,029		-59,814		163,651		-350,968		'	'
Unrealized investment gains, tax effect	12,117		20,935		-55,419		122,839		'	'
Unrealized investment gains, after-tax amounts	-12,912		-38,879		108,232		-228,129		'	'
Currency translation adjustment, pre-tax	-49,380		44,328		-28,590		-25,451		'	'
Currency translation adjustment, tax effect	0		0		0		0		'	'
Change in unrealized currency translation adjustments	-49,380		44,328		-28,590		-25,451		'	'
Net pension asset, pre-tax	3,108		2,790		7,125		8,372		'	'
Net pension asset, tax effect	-1,088		-976		-2,494		-2,930		'	'
Net pension asset, after-tax amounts	2,020		1,814		4,631		5,442		'	'
Other comprehensive income (loss), pre-tax	-71,301		-12,696		142,186		-368,047		'	'
Other comprehensive income (loss), tax effect	11,029		19,959		-57,913		119,909		'	'
Accumulated Net Unrealized Investment Gain (Loss) [Member]	'		'		'		'		'	'
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]	'		'		'		'		'	'
Accumulated Other Comprehensive Income (Loss), Beginning of Period	'		'		256,566		517,658		377,673	328,403
Other comprehensive income (loss) before reclassifications	3,099		-10,331		143,388		-172,276		'	'
Amounts reclassified from AOCI	-16,011		-28,548		-35,156		-55,853		'	'
Other comprehensive income (loss)	-12,912		-38,879		108,232		-228,129		'	'
Unrealized investment gain related to non-controlling interest	-82		-9		-119		-14		'	'
Accumulated Other Comprehensive Income (Loss), End of Period	364,679		289,515		364,679		289,515		377,673	328,403
Currency Translation Adjustments [Member]	'		'		'		'		'	'
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]	'		'		'		'		'	'
Accumulated Other Comprehensive Income (Loss), Beginning of Period	'		'		-60,524		-36,676		-39,734	-106,455
Other comprehensive income (loss) before reclassifications	-49,380		44,328		-28,590		-25,451		'	'
Amounts reclassified from AOCI	0		0		0		0		'	'
Other comprehensive income (loss)	-49,380		44,328		-28,590		-25,451		'	'
Unrealized investment gain related to non-controlling interest	0		0		0		0		'	'
Accumulated Other Comprehensive Income (Loss), End of Period	-89,114		-62,127		-89,114		-62,127		-39,734	-106,455
Change in unrealized currency translation adjustments	'		'		-28,590		-25,451		'	'
Net Pension Asset [Member]	'		'		'		'		'	'
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]	'		'		'		'		'	'
Accumulated Other Comprehensive Income (Loss), Beginning of Period	'		'		-6,651		-15,351		-4,040	-11,723
Other comprehensive income (loss) before reclassifications	0		0		0		0		'	'
Amounts reclassified from AOCI	2,020		1,814		4,631		5,442		'	'
Other comprehensive income (loss)	2,020		1,814		4,631		5,442		'	'
Unrealized investment gain related to non-controlling interest	0		0		0		0		'	'
Accumulated Other Comprehensive Income (Loss), End of Period	-2,020		-9,909		-2,020		-9,909		-4,040	-11,723
Accumulated Other Comprehensive Income (Loss) [Member]	'		'		'		'		'	'
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]	'		'		'		'		'	'
Accumulated Other Comprehensive Income (Loss), Beginning of Period	'		'		189,391		465,631		333,899	210,225
Other comprehensive income (loss) before reclassifications	-46,281		33,997		114,798		-197,727		'	'
Amounts reclassified from AOCI	-13,991		-26,734		-30,525		-50,411		'	'
Other comprehensive income (loss)	-60,272		7,263		84,273		-248,138		'	'
Unrealized investment gain related to non-controlling interest	-82		-9		-119		'		'	'
Accumulated Other Comprehensive Income (Loss), End of Period	273,545		217,479		273,545		217,479		333,899	210,225
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]	'		'		'		'		'	'
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]	'		'		'		'		'	'
Net investment gains	-24,632	[1]	-43,920		-54,086	[1]	-85,928	[1]	'	'
Tax effect	8,621	[2]	15,372	[2]	18,930	[2]	30,075	[2]	'	'
After-tax amounts reclassified	-16,011		-28,548		-35,156		-55,853		'	'
Reclassification out of Accumulated Other Comprehensive Income [Member] | Currency Translation Adjustments [Member]	'		'		'		'		'	'
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]	'		'		'		'		'	'
Income before income taxes	0		0		0		0		'	'
Tax effect	0	[2]	0	[2]	0	[2]	0	[2]	'	'
After-tax amounts reclassified	0		0		0		0		'	'
Reclassification out of Accumulated Other Comprehensive Income [Member] | Net Pension Asset [Member]	'		'		'		'		'	'
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]	'		'		'		'		'	'
Income before taxes	3,108	[3]	2,790		7,125	[3]	8,372	[3]	'	'
Tax effect	-1,088	[2]	-976	[2]	-2,494	[2]	-2,930	[2]	'	'
After-tax amounts reclassified	2,020		1,814		4,631		5,442		'	'
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Other Comprehensive Income (Loss) [Member]	'		'		'		'		'	'
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]	'		'		'		'		'	'
Income before income taxes	-21,524		-41,130		-46,961		-77,556		'	'
Tax effect	7,533	[2]	14,396	[2]	16,436	[2]	27,145	[2]	'	'
After-tax amounts reclassified	($13,991)		($26,734)		($30,525)		($50,411)		'	'
[1]	Net investment gains in the consolidated statements of
[2]	Income tax expense in the consolidated statements of income.
[3]	Other operating costs and expenses in the consolidated statements of income.

Statements_of_Cash_Flow_Detail

Statements of Cash Flow (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Supplemental Cash Flow Information [Abstract]	'	'
Interest payments	$108,688,000	$114,026,000
Income taxes paid	$238,030,000	$176,632,000

Investments_In_Fixed_Maturity_2

Investments In Fixed Maturity Securities Investments in Fixed Maturity Securities (Investments in fixed maturity securities) (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'		'
Total held to maturity, Amortized Cost	$101,196,000		$101,320,000
Held to Maturity Securities Accumulated Unrecognized Holding Gain	20,260,000		14,900,000
Held to Maturity Securities Accumulated Unrecognized Holding Loss	0		0
Total held to maturity, Fair Value	121,456,000		116,220,000
Total held to maturity, Carrying Value	101,196,000		101,320,000
Total available for sale, Amortized Cost	11,780,111,000		11,190,311,000
Total available for sale, Gross Unrealized Gains	571,004,000		436,347,000
Total available for sale, Gross Unrealized Losses	-54,555,000		-111,134,000
Total available for sale, Fair Value	12,296,560,000		11,515,524,000
Total available for sale, Carrying Value	12,296,560,000		11,515,524,000
Total investments in fixed maturity securities, Amortized Value	11,881,307,000		11,291,631,000
Total investments in fixed maturity securities, Gross Unrealized Gains	591,264,000		451,247,000
Total investments in fixed maturity securities, Gross Unrealized Losses	-54,555,000		-111,134,000
Total investments in fixed maturity securities, Fair Value	12,418,016,000		11,631,744,000
Total investments in fixed maturity securities, Carrying Value	12,397,756,000		11,616,844,000
Minimum ownership of Common stockholders equity	10.00%		'
Foreign government	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Total available for sale, Amortized Cost	880,959,000		844,469,000
Total available for sale, Gross Unrealized Gains	95,159,000		51,674,000
Total available for sale, Gross Unrealized Losses	-13,207,000		-16,286,000
Total available for sale, Fair Value	962,911,000		879,857,000
Total available for sale, Carrying Value	962,911,000		879,857,000
Commercial Mortgage Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Total available for sale, Amortized Cost	76,993,000		76,454,000
Total available for sale, Gross Unrealized Gains	976,000		5,670,000
Total available for sale, Gross Unrealized Losses	-83,000		-988,000
Total available for sale, Fair Value	77,886,000		81,136,000
Total available for sale, Carrying Value	77,886,000		81,136,000
U.S. government and government agency	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Total available for sale, Amortized Cost	787,967,000		858,319,000
Total available for sale, Gross Unrealized Gains	30,296,000		34,522,000
Total available for sale, Gross Unrealized Losses	-5,229,000		-7,982,000
Total available for sale, Fair Value	813,034,000		884,859,000
Total available for sale, Carrying Value	813,034,000		884,859,000
Residential Mortgage Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Total available for sale, Amortized Cost	1,209,068,000	[1]	1,248,693,000	[1]
Total available for sale, Gross Unrealized Gains	26,100,000	[1]	25,895,000	[1]
Total available for sale, Gross Unrealized Losses	-14,209,000	[1]	-25,941,000	[1]
Total available for sale, Fair Value	1,220,959,000	[1]	1,248,647,000	[1]
Total available for sale, Carrying Value	1,220,959,000	[1]	1,248,647,000	[1]
Non-credit portion of other-than-temporary impairments (OTTI)	1,020,000		1,961,000
Corporate Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Total available for sale, Amortized Cost	4,866,983,000		4,076,585,000
Total available for sale, Gross Unrealized Gains	191,727,000		156,256,000
Total available for sale, Gross Unrealized Losses	-17,008,000		-30,100,000
Total available for sale, Fair Value	5,041,702,000		4,202,741,000
Total available for sale, Carrying Value	5,041,702,000		4,202,741,000
State and municipal	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Total available for sale, Amortized Cost	3,958,141,000		4,085,791,000
Total available for sale, Gross Unrealized Gains	226,746,000		162,330,000
Total available for sale, Gross Unrealized Losses	-4,819,000		-29,837,000
Total available for sale, Fair Value	4,180,068,000		4,218,284,000
Total available for sale, Carrying Value	4,180,068,000		4,218,284,000
State and municipal	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Total held to maturity, Amortized Cost	71,897,000		68,929,000
Held to Maturity Securities Accumulated Unrecognized Holding Gain	16,991,000		11,172,000
Held to Maturity Securities Accumulated Unrecognized Holding Loss	0		0
Total held to maturity, Fair Value	88,888,000		80,101,000
Total held to maturity, Carrying Value	71,897,000		68,929,000
Residential Mortgage Backed Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Total held to maturity, Amortized Cost	24,300,000		27,393,000
Held to Maturity Securities Accumulated Unrecognized Holding Gain	2,901,000		3,311,000
Held to Maturity Securities Accumulated Unrecognized Holding Loss	0		0
Total held to maturity, Fair Value	27,201,000		30,704,000
Total held to maturity, Carrying Value	24,300,000		27,393,000
Corporate Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Total held to maturity, Amortized Cost	4,999,000		4,998,000
Held to Maturity Securities Accumulated Unrecognized Holding Gain	368,000		417,000
Held to Maturity Securities Accumulated Unrecognized Holding Loss	0		0
Total held to maturity, Fair Value	5,367,000		5,415,000
Total held to maturity, Carrying Value	$4,999,000		$4,998,000
[1]	Gross unrealized losses for residential mortgage-backed securities include $1,020,000 and $1,961,000 as of September 30, 2014 and December 31, 2013, respectively, related to the non-credit portion of other-than-temporary impairments (“OTTI”) recognized in accumulated other comprehensive income.

Investments_In_Fixed_Maturity_3

Investments In Fixed Maturity Securities Investments in Fixed Maturity Securities (Amortized cost and fair value of fixed maturity securities) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investments, Debt and Equity Securities [Abstract]	'	'
Amortized Cost, Due in one year or less	$889,062	'
Amortized Cost, Due after one year through five years	4,052,836	'
Amortized Cost, Due after five years through ten years	3,105,077	'
Amortized Cost, Due after ten years	2,523,971	'
Amortized Cost, Mortgaged-backed securities	1,310,361	'
Total investments in fixed maturity securities, Amortized Value	11,881,307	11,291,631
Fair Value, Due in one year or less	900,273	'
Fair Value, Due after one year through five years	4,268,705	'
Fair Value, Due after five years through ten years	3,288,731	'
Fair Value, Due after ten years	2,634,261	'
Fair Value, Mortgage-backed securities	1,326,046	'
Total investments in fixed maturity securities, Fair Value	$12,418,016	$11,631,744

Investments_in_Equity_Securiti2

Investments in Equity Securities (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	$161,529	$203,627
Gross Unrealized, Gains	64,205	86,030
Gross Unrealized, Losses	-3,710	-6,319
Carrying and fair value of equity securities	222,024	283,338
Common stocks	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	68,762	118,536
Gross Unrealized, Gains	11,742	42,239
Gross Unrealized, Losses	-531	0
Carrying and fair value of equity securities	79,973	160,775
Preferred stocks	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Cost	92,767	85,091
Gross Unrealized, Gains	52,463	43,791
Gross Unrealized, Losses	-3,179	-6,319
Carrying and fair value of equity securities	$142,051	$122,563

Arbitrage_Trading_Account_Deta

Arbitrage Trading Account (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Trading Securities [Abstract]	'	'
Arbitrage trading account	$918,223	$522,128

Net_Investment_Income_Net_Inve1

Net Investment Income Net Investment Income (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net Investment Income [Line Items]	'	'	'	'
Investment income	$180,824	$127,541	$494,312	$411,001
Investment expense	-1,599	-1,907	-7,647	-5,701
Net investment income	179,225	125,634	486,665	405,300
Fixed maturity securities, including cash and cash equivalents and loans receivable	'	'	'	'
Net Investment Income [Line Items]	'	'	'	'
Investment income	117,289	104,033	331,947	333,072
Investment funds	'	'	'	'
Net Investment Income [Line Items]	'	'	'	'
Investment income	59,077	5,492	135,232	45,248
Arbitrage trading account	'	'	'	'
Net Investment Income [Line Items]	'	'	'	'
Investment income	47	11,738	12,508	14,265
Equity securities available for sale	'	'	'	'
Net Investment Income [Line Items]	'	'	'	'
Investment income	1,369	3,192	5,418	9,073
Real estate	'	'	'	'
Net Investment Income [Line Items]	'	'	'	'
Investment income	$3,042	$3,086	$9,207	$9,343

Investment_Funds_Investment_Fu2

Investment Funds Investment Funds (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]	'	'	'
Investment funds	$1,020,132	'	$1,067,495
Income from Investment Funds	135,232	45,248	'
Real estate	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'
Investment funds	282,431	'	378,435
Income from Investment Funds	24,341	5,777	'
Energy	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'
Investment funds	159,857	'	155,026
Income from Investment Funds	18,136	25,959	'
Arbitrage	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'
Investment funds	286,845	'	271,575
Income from Investment Funds	15,270	3,050	'
Other	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'
Investment funds	290,999	'	262,459
Income from Investment Funds	$77,485	$10,462	'

Real_Estate_Real_Estate_Detail

Real Estate Real Estate (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Real Estate [Abstract]	'	'
Properties in operation	$196,884	$283,393
Properties under development	507,110	431,849
Total	703,994	715,242
Real Estate Investment Property, Accumulated Depreciation	$68	$17,827

Real_Estate_Real_Estate_Detail1

Real Estate Real Estate (Details 1) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Real Estate [Abstract]	'	'	'
Accumulated depreciation and amortization on properties	$68	'	$17,827
Real estate depreciation expense	3,228	5,111	'
Lease future minimum payments 2014	2,820	'	'
Lease future minimum payments 2015	11,360	'	'
Lease future minimum payments 2016	11,379	'	'
Lease future minimum payments 2016	11,420	'	'
Lease future minimum payments 2014	10,750	'	'
Lease future minimum payments after 2017	$343,903	'	'

Loans_Receivable_Details

Loans Receivable (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Financing Receivable, Recorded Investment, Nonaccrual Status	$15,200,000	'	$15,200,000	'	'
Loans and Leases Receivable, Gross	343,300,000	'	343,300,000	'	343,583,000
Loans receivable	346,622,000	'	346,622,000	'	346,746,000
Valuation allowance, specific	115,000	'	115,000	'	0
Valuation allowance, general	2,427,000	'	2,427,000	'	2,087,000
Valuation allowance of loans receivable	2,542,000	'	2,542,000	'	2,087,000
Decrease in valuation allowance	-24,000	72,000	455,000	137,000	'
Loans receivable charged off	0	0	0	0	'
Real Estate	'	'	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Loans and Leases Receivable, Gross	259,522,000	'	259,522,000	'	282,357,000
Loans receivable	261,342,000	'	261,342,000	'	284,017,000
Commercial	'	'	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Loans and Leases Receivable, Gross	83,778,000	'	83,778,000	'	61,226,000
Loans receivable	$85,280,000	'	$85,280,000	'	$62,729,000

Realized_And_Unrealized_Invest2

Realized And Unrealized Investment Gains Realized and Unrealized Investment Gains (Loss) (Realized and unrealized investmetns gains(losses)) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Investments, Debt and Equity Securities [Abstract]	'	'	'	'
Fixed maturity securities, gains	$13,803	$19,500	$17,263	$39,643
Fixed maturity securities, losses	-2,208	-739	-3,727	-12,205
Equity securities available for sale	9,729	25,158	39,310	58,489
Investment funds	50,919	-34	95,675	11,003
Real Estate Realized Gain (Loss) on Disposal	15	0	85,659	0
Other	0	-16	0	-34
Realized Gain (Loss) on Investments, Including Equity Method Investments, Excluding Other than Temporary Impairments and Allowances	72,258	43,869	234,180	96,896
Net investment gains	72,258	43,869	234,180	96,896
Income tax expense	-25,290	-15,355	-81,963	-33,914
Total after-tax realized investment gains	$46,968	$28,514	$152,217	$62,982

Recovered_Sheet2

Realized and Unrealized Investment Gains (Losses) (Change in Unrealized Gains (Losses) of Available For Sales Securities) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Realized and Unrealized Investment Gains Losses [Line Items]	'	'	'	'
Change in unrealized gains (losses) before income taxes and noncontrolling interests	($25,029)	($55,763)	$163,651	($349,425)
Income tax benefit (expense)	12,117	16,884	-55,419	121,296
Noncontrolling interests	-82	-9	-119	-14
Total change in unrealized gains	-12,994	-38,888	108,113	-228,143
Debt Securities [Member]	'	'	'	'
Realized and Unrealized Investment Gains Losses [Line Items]	'	'	'	'
Change in unrealized gains (losses) before income taxes and noncontrolling interests	10,722	-46,004	190,242	-339,384
Debt Securities Previously Impaired [Member]	'	'	'	'
Realized and Unrealized Investment Gains Losses [Line Items]	'	'	'	'
Change in unrealized gains (losses) before income taxes and noncontrolling interests	188	299	941	821
Equity securities available for sale	'	'	'	'
Realized and Unrealized Investment Gains Losses [Line Items]	'	'	'	'
Change in unrealized gains (losses) before income taxes and noncontrolling interests	-27,548	-13,984	-19,215	-5,614
Investment funds	'	'	'	'
Realized and Unrealized Investment Gains Losses [Line Items]	'	'	'	'
Change in unrealized gains (losses) before income taxes and noncontrolling interests	($8,391)	$3,926	($8,317)	($5,248)

Securities_In_An_Unrealized_Lo2

Securities In An Unrealized Loss Position Securities in an Unrealized Loss Position (Securities in an Unrealized Loss Position) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	$1,590,409	$3,085,977
Gross Unrealized Losses, Less than 12 Months	11,343	84,259
Fair Value, 12 Months or Greater	968,927	355,098
Gross Unrealized Losses, 12 Months or Greater	46,922	33,194
Fair Value, Total	2,559,336	3,441,075
Gross Unrealized Losses, Total	58,265	117,453
U.S. government and government agency	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	131,471	260,882
Gross Unrealized Losses, Less than 12 Months	1,411	7,927
Fair Value, 12 Months or Greater	85,253	2,163
Gross Unrealized Losses, 12 Months or Greater	3,818	55
Fair Value, Total	216,724	263,045
Gross Unrealized Losses, Total	5,229	7,982
State and municipal	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	111,019	899,613
Gross Unrealized Losses, Less than 12 Months	743	24,503
Fair Value, 12 Months or Greater	175,757	87,345
Gross Unrealized Losses, 12 Months or Greater	4,076	5,334
Fair Value, Total	286,776	986,958
Gross Unrealized Losses, Total	4,819	29,837
Mortgage-backed securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	182,774	578,603
Gross Unrealized Losses, Less than 12 Months	1,481	17,964
Fair Value, 12 Months or Greater	295,503	140,648
Gross Unrealized Losses, 12 Months or Greater	12,811	8,965
Fair Value, Total	478,277	719,251
Gross Unrealized Losses, Total	14,292	26,929
Corporate Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	1,068,868	1,013,373
Gross Unrealized Losses, Less than 12 Months	3,983	17,066
Fair Value, 12 Months or Greater	269,171	105,074
Gross Unrealized Losses, 12 Months or Greater	13,025	13,034
Fair Value, Total	1,338,039	1,118,447
Gross Unrealized Losses, Total	17,008	30,100
Foreign government	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	82,459	320,215
Gross Unrealized Losses, Less than 12 Months	3,154	16,286
Fair Value, 12 Months or Greater	120,708	0
Gross Unrealized Losses, 12 Months or Greater	10,053	0
Fair Value, Total	203,167	320,215
Gross Unrealized Losses, Total	13,207	16,286
Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	1,576,591	3,072,686
Gross Unrealized Losses, Less than 12 Months	10,772	83,746
Fair Value, 12 Months or Greater	946,392	335,230
Gross Unrealized Losses, 12 Months or Greater	43,783	27,388
Fair Value, Total	2,522,983	3,407,916
Gross Unrealized Losses, Total	54,555	111,134
Common stocks	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	10,813	0
Gross Unrealized Losses, Less than 12 Months	531	0
Fair Value, 12 Months or Greater	0	0
Gross Unrealized Losses, 12 Months or Greater	0	0
Fair Value, Total	10,813	0
Gross Unrealized Losses, Total	531	0
Preferred stocks	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	3,005	13,291
Gross Unrealized Losses, Less than 12 Months	40	513
Fair Value, 12 Months or Greater	22,535	19,868
Gross Unrealized Losses, 12 Months or Greater	3,139	5,806
Fair Value, Total	25,540	33,159
Gross Unrealized Losses, Total	3,179	6,319
Equity securities available for sale	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Fair Value, Less than 12 Months	13,818	13,291
Gross Unrealized Losses, Less than 12 Months	571	513
Fair Value, 12 Months or Greater	22,535	19,868
Gross Unrealized Losses, 12 Months or Greater	3,139	5,806
Fair Value, Total	36,353	33,159
Gross Unrealized Losses, Total	$3,710	$6,319

Securities_In_An_Unrealized_Lo3

Securities In An Unrealized Loss Position Non-Investment Grade Fixed Maturity Securities (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Aggregate fair value of securities in a continuous unrealized loss position	$2,559,336	$3,441,075
Mortgage-backed securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Aggregate fair value of securities in a continuous unrealized loss position	478,277	719,251
Corporate Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Aggregate fair value of securities in a continuous unrealized loss position	1,338,039	1,118,447
State and municipal	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Aggregate fair value of securities in a continuous unrealized loss position	286,776	986,958
Foreign government	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Aggregate fair value of securities in a continuous unrealized loss position	203,167	320,215
Noninvestment Grade Investments at Loss Less than 5 Million	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of Securities	18	'
Aggregate fair value of securities in a continuous unrealized loss position	69,724	'
Gross Unrealized Loss	2,258	'
Noninvestment Grade Investments at Loss Less than 5 Million | Mortgage-backed securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of Securities	9	'
Aggregate fair value of securities in a continuous unrealized loss position	42,230	'
Gross Unrealized Loss	1,611	'
Noninvestment Grade Investments at Loss Less than 5 Million | Corporate Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of Securities	9	'
Aggregate fair value of securities in a continuous unrealized loss position	27,494	'
Gross Unrealized Loss	647	'
Noninvestment Grade Investments at Loss Less than 5 Million | Foreign government	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of Securities	0	'
Aggregate fair value of securities in a continuous unrealized loss position	0	'
Gross Unrealized Loss	$0	'

Securities_In_An_Unrealized_Lo4

Securities In An Unrealized Loss Position Securities In An Unrealized Loss Position (Narrative) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Aggregate fair value of securities in a continuous unrealized loss position	$2,559,336	$3,441,075
Gross Unrealized Losses	58,265	117,453
Preferred stocks	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Aggregate fair value of securities in a continuous unrealized loss position	25,540	33,159
Gross Unrealized Losses	3,179	6,319
Preferred stocks | Noninvestment Grade Investments [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of Securities	2	'
Aggregate fair value of securities in a continuous unrealized loss position	26,000	'
Gross Unrealized Losses	3,000	'
Common stocks	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Aggregate fair value of securities in a continuous unrealized loss position	10,813	0
Gross Unrealized Losses	$531	$0

Fair_Value_Measurements_Assets

Fair Value Measurements (Assets and Liabilities Measured At Fair Value, On a Recurring Basis) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	$12,296,560	$11,515,524
Equity securities	222,024	283,338
Arbitrage trading account	918,223	522,128
Level 1 | Fair Value, Measurements, Recurring [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	0	0
Equity securities	68,852	159,537
Assets, fair value disclosure	306,162	351,818
Arbitrage trading account	237,310	192,281
Securities sold but not yet purchased	159,501	162,126
Level 1 | Fair Value, Measurements, Recurring [Member] | U.S. government and government agency	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	0	0
Level 1 | Fair Value, Measurements, Recurring [Member] | State and municipal	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	0	0
Level 1 | Fair Value, Measurements, Recurring [Member] | Mortgage-backed securities	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	0	0
Level 1 | Fair Value, Measurements, Recurring [Member] | Corporate	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	0	0
Level 1 | Fair Value, Measurements, Recurring [Member] | Foreign government	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	0	0
Level 1 | Fair Value, Measurements, Recurring [Member] | Common stocks	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities	68,852	159,537
Level 1 | Fair Value, Measurements, Recurring [Member] | Preferred stocks	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities	0	0
Level 2 | Fair Value, Measurements, Recurring [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	12,272,560	11,472,660
Equity securities	138,313	118,811
Assets, fair value disclosure	13,087,769	11,919,538
Arbitrage trading account	676,896	328,067
Securities sold but not yet purchased	5	152
Level 2 | Fair Value, Measurements, Recurring [Member] | U.S. government and government agency	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	813,034	884,859
Level 2 | Fair Value, Measurements, Recurring [Member] | State and municipal	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	4,180,068	4,218,284
Level 2 | Fair Value, Measurements, Recurring [Member] | Mortgage-backed securities	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	1,298,845	1,329,783
Level 2 | Fair Value, Measurements, Recurring [Member] | Corporate	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	5,017,702	4,159,877
Level 2 | Fair Value, Measurements, Recurring [Member] | Foreign government	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	962,911	879,857
Level 2 | Fair Value, Measurements, Recurring [Member] | Common stocks	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities	0	0
Level 2 | Fair Value, Measurements, Recurring [Member] | Preferred stocks	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities	138,313	118,811
Level 3 | Fair Value, Measurements, Recurring [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	24,000	42,864
Equity securities	14,859	4,990
Assets, fair value disclosure	42,876	49,634
Arbitrage trading account	4,017	1,780
Securities sold but not yet purchased	31	0
Level 3 | Fair Value, Measurements, Recurring [Member] | U.S. government and government agency	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	0	0
Level 3 | Fair Value, Measurements, Recurring [Member] | State and municipal	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	0	0
Level 3 | Fair Value, Measurements, Recurring [Member] | Mortgage-backed securities	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	0	0
Level 3 | Fair Value, Measurements, Recurring [Member] | Corporate	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	24,000	42,864
Level 3 | Fair Value, Measurements, Recurring [Member] | Foreign government	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	0	0
Level 3 | Fair Value, Measurements, Recurring [Member] | Common stocks	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities	11,121	1,238
Level 3 | Fair Value, Measurements, Recurring [Member] | Preferred stocks	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities	3,738	3,752
Fair Value | Fair Value, Measurements, Recurring [Member]	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	12,296,560	11,515,524
Equity securities	222,024	283,338
Assets, fair value disclosure	13,436,807	12,320,990
Arbitrage trading account	918,223	522,128
Securities sold but not yet purchased	159,537	162,278
Fair Value | Fair Value, Measurements, Recurring [Member] | U.S. government and government agency	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	813,034	884,859
Fair Value | Fair Value, Measurements, Recurring [Member] | State and municipal	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	4,180,068	4,218,284
Fair Value | Fair Value, Measurements, Recurring [Member] | Mortgage-backed securities	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	1,298,845	1,329,783
Fair Value | Fair Value, Measurements, Recurring [Member] | Corporate	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	5,041,702	4,202,741
Fair Value | Fair Value, Measurements, Recurring [Member] | Foreign government	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Fixed maturity securities	962,911	879,857
Fair Value | Fair Value, Measurements, Recurring [Member] | Common stocks	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities	79,973	160,775
Fair Value | Fair Value, Measurements, Recurring [Member] | Preferred stocks	'	'
Fair Value Measurements, Recurring and Nonrecurring Basis [Line Items]	'	'
Equity securities	$142,051	$122,563

Fair_Value_Measurements_Fair_V1

Fair Value Measurements Fair Value Measurements (Summarize Changes in Level 3 Assets) (Details) (Level 3, USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Assets, beginning balance	$49,634	$62,022
Assets, earnings	2,351	1,836
Assets, other comprehensive income	-1,677	1,039
Assets, purchases	19,799	4,424
Assets, (sales)	-33,688	-5,776
Assets, maturities	2,607	12,604
Assets, transfers in	9,064	-1,307
Assets, ending balance	42,876	49,634
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Liabilities, beginning balance	0	20
Liabilities, earnings	0	-4
Liabilities, other comprehensive income	0	0
Liabilities, purchases	31	4
Liabilities, (sales)	0	-20
Liabilities, maturities	0	0
Liabilities, transfers in	0	0
Liabilities, ending balance	31	0
Equity securities available for sale	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Assets, beginning balance	4,990	2,029
Assets, earnings	8	-299
Assets, other comprehensive income	-531	0
Assets, purchases	14,773	3,430
Assets, (sales)	-4,381	-170
Assets, maturities	'	'
Assets, transfers in	0	0
Assets, ending balance	14,859	4,990
Preferred stocks	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Assets, beginning balance	3,752	621
Assets, earnings	8	-299
Assets, other comprehensive income	0	0
Assets, purchases	3,430	3,430
Assets, (sales)	-3,452	0
Assets, maturities	'	'
Assets, transfers in	0	0
Assets, ending balance	3,738	3,752
Common stocks	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Assets, beginning balance	1,238	1,408
Assets, earnings	0	0
Assets, other comprehensive income	-531	0
Assets, purchases	11,343	0
Assets, (sales)	-929	-170
Assets, maturities	'	'
Assets, transfers in	0	0
Assets, ending balance	11,121	1,238
Debt Securities [Member]	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Assets, beginning balance	42,864	59,065
Assets, earnings	49	677
Assets, other comprehensive income	-1,146	309
Assets, purchases	84	170
Assets, (sales)	-15,244	-4,753
Assets, maturities	2,607	12,604
Assets, transfers in	0	0
Assets, ending balance	24,000	42,864
Corporate Debt Securities [Member]	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Assets, beginning balance	42,864	59,065
Assets, earnings	49	677
Assets, other comprehensive income	-1,146	309
Assets, purchases	84	170
Assets, (sales)	-15,244	-4,753
Assets, maturities	2,607	12,604
Assets, transfers in	0	0
Assets, ending balance	24,000	42,864
Trading Assets, Excluding Debt and Equity Securities [Member]	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Assets, beginning balance	1,780	928
Assets, earnings	2,294	1,458
Assets, other comprehensive income	0	730
Assets, purchases	4,942	824
Assets, (sales)	-14,063	-853
Assets, maturities	'	'
Assets, transfers in	9,064	-1,307
Assets, ending balance	$4,017	$1,780

Reinsurance_Reinsurance_Detail

Reinsurance Reinsurance (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Premiums Written	'	'	'	'	'
Written premiums, direct	$1,553,493,000	$1,415,775,000	$4,699,319,000	$4,221,370,000	'
Written premiums, assumed	225,863,000	251,331,000	657,704,000	695,293,000	'
Written premiums, ceded	-253,974,000	-243,481,000	-815,985,000	-774,174,000	'
Total net premiums written	1,525,382,000	1,423,625,000	4,541,038,000	4,142,489,000	'
Premiums Earned	'	'	'	'	'
Earned premiums, direct	1,505,738,000	1,351,542,000	4,336,463,000	3,893,806,000	'
Earned premiums, assumed	216,889,000	226,530,000	667,566,000	658,063,000	'
Earned premiums, ceded	-261,823,000	-249,210,000	-761,968,000	-708,373,000	'
Net premiums earned	1,460,804,000	1,328,862,000	4,242,061,000	3,843,496,000	'
Ceded losses incurred	128,903,000	186,504,000	319,156,000	439,415,000	'
Uncollectible reinsurance	$2,000,000	'	$2,000,000	'	$1,000,000

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Carrying Amounts and Estimated Fair Values of Financial Instruments) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets:	'	'
Arbitrage trading account	$918,223	$522,128
Loans receivable	346,622	346,746
Payables to Broker-Dealers and Clearing Organizations	95,681	0
Carrying Value	'	'
Assets:	'	'
Fixed maturity securities	12,397,756	11,616,844
Equity securities available for sale	222,024	283,338
Arbitrage trading account	918,223	522,128
Loans receivable	343,300	343,583
Cash and cash equivalents	1,342,285	839,738
Trading account receivables from brokers and clearing organizations	0	304,936
Due from broker	0	17,735
Due from broker fair value	58,926	8,273
Liabilities:	'	'
Trading account securities sold but not yet purchased	159,537	162,278
Junior subordinated debentures	339,995	339,800
Senior notes and other debt	2,122,030	1,692,442
Fair Value	'	'
Assets:	'	'
Fixed maturity securities	12,418,016	11,631,744
Equity securities available for sale	222,024	283,338
Arbitrage trading account	918,223	522,128
Loans receivable	346,622	346,746
Cash and cash equivalents	1,342,285	839,738
Trading account receivables from brokers and clearing organizations	0	304,936
Due from broker	0	17,735
Liabilities:	'	'
Trading account securities sold but not yet purchased	159,537	162,278
Junior subordinated debentures	326,480	288,540
Senior notes and other debt	$2,341,816	$1,861,898

Restricted_Stock_Units_Summary

Restricted Stock Units (Summary of Restricted Stock Units Issued) (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]	'	'
Share based compensation expense	$20,000,000	$16,000,000
Restricted Stock [Member]	'	'
Share-Based Compensation Arrangement by Share-based Payment Award [Line Item]	'	'
Award vesting period	'5 years	'
Restricted Stock Units	1,135,900	93,150
Restricted Stock Units, Fair Value	$50,791,000	$3,957,000

Industry_Segments_Financial_In

Industry Segments (Financial Information of Company Operating Segments) (Details) (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Segment Reporting Information [Line Items]	'		'		'		'
Earned Premiums	$1,460,804		$1,328,862		$4,242,061		$3,843,496
Investment Income and Funds	179,225		125,634		486,665		405,300
Other Revenues	200,576		179,628		615,774		463,059
Total revenues	1,840,605		1,634,124		5,344,500		4,711,855
Pre-Tax Income (Loss)	278,453		198,233		789,492		517,162
Net Income (Loss)	188,539		136,974		538,173		369,546
Net investment gains	72,258		43,869		234,180		96,896
Net investment gains, net of tax	46,968		28,514		152,217		62,982
Intersegment Eliminations and Corporate, Non-Segment [Member]	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Earned Premiums	0	[1]	0	[1]	0	[1]	0	[1]
Investment Income and Funds	6,560	[1]	291	[1]	19,676	[1]	3,831	[1]
Other Revenues	101,910	[1]	109,634	[1]	299,435	[1]	285,650	[1]
Total revenues	108,470	[1]	109,925	[1]	319,111	[1]	289,481	[1]
Pre-Tax Income (Loss)	-63,772	[1]	-58,501	[1]	-180,892	[1]	-183,941	[1]
Net Income (Loss)	-42,571	[1]	-38,248	[1]	-119,194	[1]	-114,674	[1]
Insurance-Domestic Segment [Member]	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Earned Premiums	1,093,554		958,994		3,138,806		2,769,369
Insurance-Domestic Segment [Member] | Operating Segments [Member]	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Earned Premiums	1,093,554		958,994		3,138,806		2,769,369
Investment Income and Funds	125,792		94,071		347,002		299,430
Other Revenues	26,408		26,125		82,159		80,513
Total revenues	1,245,754		1,079,190		3,567,967		3,149,312
Pre-Tax Income (Loss)	228,359		172,177		607,399		465,861
Net Income (Loss)	154,718		118,183		414,588		324,069
Insurance-International Segment [Member]	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Earned Premiums	205,529		189,054		592,721		540,365
Insurance-International Segment [Member] | Operating Segments [Member]	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Earned Premiums	205,529		189,054		592,721		540,365
Investment Income and Funds	19,957		11,151		47,885		36,383
Other Revenues	0		0		0		0
Total revenues	225,486		200,205		640,606		576,748
Pre-Tax Income (Loss)	12,603		16,129		41,860		51,094
Net Income (Loss)	9,217		11,225		29,938		35,794
Reinsurance-Global Segment [Member]	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Earned Premiums	161,721		180,814		510,534		533,762
Reinsurance-Global Segment [Member] | Operating Segments [Member]	'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'
Earned Premiums	161,721		180,814		510,534		533,762
Investment Income and Funds	26,916		20,121		72,102		65,656
Other Revenues	0		0		0		0
Total revenues	188,637		200,935		582,636		599,418
Pre-Tax Income (Loss)	29,005		24,559		86,945		87,252
Net Income (Loss)	$20,207		$17,300		$60,624		$61,375
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Industry_Segments_Identifiable

Industry Segments (Identifiable Assets by Segment) (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Segment Reporting, Asset Reconciling Item [Line Items]	'		'
Consolidated Assets	$22,097,597		$20,551,796
Operating Segments [Member] | Reinsurance-Global Segment [Member]	'		'
Segment Reporting, Asset Reconciling Item [Line Items]	'		'
Consolidated Assets	2,801,268		3,103,193
Operating Segments [Member] | Insurance-International Segment [Member]	'		'
Segment Reporting, Asset Reconciling Item [Line Items]	'		'
Consolidated Assets	1,915,322		1,516,310
Operating Segments [Member] | Insurance-Domestic Segment [Member]	'		'
Segment Reporting, Asset Reconciling Item [Line Items]	'		'
Consolidated Assets	16,074,387		15,247,807
Intersegment Eliminations and Corporate, Non-Segment [Member]	'		'
Segment Reporting, Asset Reconciling Item [Line Items]	'		'
Consolidated Assets	$1,306,620	[1]	$684,486	[1]
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Industry_Segments_Industry_Seg

Industry Segments Industry Segments (Net Premiums Earned By Major Line of Business) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	$1,460,804	$1,328,862	$4,242,061		$3,843,496
Insurance-Domestic Segment [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	1,093,554	958,994	3,138,806		2,769,369
Insurance-Domestic Segment [Member] | Other Insurance Liabilities [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	368,818	314,878	1,070,525		917,910
Insurance-Domestic Segment [Member] | Workers' Compensation [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	291,297	252,220	824,541		722,422
Insurance-Domestic Segment [Member] | Property [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	222,561	199,181	642,833	[1]	570,868	[1]
Insurance-Domestic Segment [Member] | Commercial Automobile [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	134,197	125,942	385,667		361,964
Insurance-Domestic Segment [Member] | Products Liability [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	76,681	66,773	215,240		196,205
Insurance-International Segment [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	205,529	189,054	592,721		540,365
Insurance-International Segment [Member] | Other Insurance Liabilities [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	27,705	18,457	70,036		48,745
Insurance-International Segment [Member] | Workers' Compensation [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	18,012	20,847	52,578		65,482
Insurance-International Segment [Member] | Property [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	100,417	92,213	303,119	[1]	248,637	[1]
Insurance-International Segment [Member] | Commercial Automobile [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	29,076	30,898	86,318		97,929
Insurance-International Segment [Member] | Products Liability [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	30,319	26,639	80,670		79,572
Reinsurance-Global Segment [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	161,721	180,814	510,534		533,762
Reinsurance-Global Segment [Member] | Property [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	38,980	52,687	137,640		162,191
Reinsurance-Global Segment [Member] | Casualty [Member]	'	'	'		'
Revenue from External Customer [Line Items]	'	'	'		'
Premiums Earned, Net	$122,741	$128,127	$372,894		$371,571
[1]	For the Three Months For the Nine Months Ended September 30, Ended September 30,(In thousands)2014 2013 2014 2013 Insurance-Domestic: Other liability$368,818 $314,878 $1,070,525 $917,910Workers’ compensation291,297 252,220 824,541 722,422Short-tail lines 222,561 199,181 642,833 570,868Commercial automobile134,197 125,942 385,667 361,964Professional liability76,681 66,773 215,240 196,205Total1,093,554 958,994 3,138,806 2,769,369 Insurance-International: Other liability27,705 18,457 70,036 48,745Workers’ compensation18,012 20,847 52,578 65,482Short-tail lines100,417 92,213 303,119 248,637Commercial automobile29,076 30,898 86,318 97,929Professional liability30,319 26,639 80,670 79,572Total205,529 189,054 592,721 540,365 Reinsurance-Global: Casualty122,741 128,127 372,894 371,571Property38,980 52,687 137,640 162,191Total161,721 180,814 510,534 533,762 Total$1,460,804 $1,328,862 $4,242,061 $3,843,496