Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 100,141	$ 243,753	$ 344,781	$ 614,666
Adjustments to reconcile net income to net cash provided by operating activities:
Decrease (increase) in premiums receivable	(154,853)	(185,115)	(237,390)	(382,658)
Decrease (increase) in funds held by reinsureds, net	361	285	762	(12,201)
Decrease (increase) in reinsurance receivables	(409,980)	(91,047)	(778,374)	(177,199)
Decrease (increase) in income taxes	(24,615)	129,344	12,264	252,746
Decrease (increase) in prepaid reinsurance premiums	(98,231)	(78,068)	(198,306)	(132,217)
Increase (decrease) in reserve for losses and loss adjustment expenses	142,529	(136,110)	150,411	(390,402)
Increase (decrease) in unearned premiums	140,386	140,204	241,650	263,018
Increase (decrease) in other net payable to reinsurers	270,262	147,164	353,468	264,061
Increase (decrease) in losses in course of payment	12,569	182,448	164,072	417,982
Change in equity adjustments in limited partnerships	(18,804)	(6,337)	(17,643)	(31,159)
Distribution of limited partnership income	23,391	2,683	32,548	18,868
Change in other assets and liabilities, net	49,157	19,626	(2,744)	7,875
Non-cash compensation expense	2,002	2,257	5,700	6,230
Amortization of bond premium (accrual of bond discount)	2,921	5,999	14,502	19,696
Amortization of underwriting discount on senior notes	15	14	43	41
Net realized capital (gains) losses	160	(208,426)	(120,904)	(533,758)
Net cash provided by (used in) operating activities	37,411	168,674	(35,160)	205,589
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from fixed maturities matured/called - available for sale, at market value	309,630	258,451	829,363	885,835
Proceeds from fixed maturities matured/called - available for sale, at fair value			875	7,213
Proceeds from fixed maturities sold - available for sale, at market value	219,823	124,460	547,682	465,084
Proceeds from fixed maturities sold - available for sale, at fair value	3,092	1,056	23,855	18,398
Proceeds from equity securities sold - available for sale, at fair value	111,684	95,174	404,627	450,020
Distributions from other invested assets	26,583	3,973	41,854	47,576
Cost of fixed maturities acquired - available for sale, at market value	(509,564)	(313,538)	(2,008,937)	(1,314,440)
Cost of fixed maturities acquired - available for sale, at fair value	(22,375)	(2,092)	(23,684)	(4,798)
Cost of equity securities acquired - available for sale, at fair value	(74,297)	(98,760)	(237,749)	(332,434)
Cost of other invested assets acquired	(43,953)	(3,320)	(76,717)	(11,828)
Net change in short-term investments	13,327	(86,361)	97,262	10,316
Net change in unsettled securities transactions	(16,427)	16,401	(9,474)	(15,982)
Net cash provided by (used in) investing activities	17,523	(4,556)	(411,043)	204,960
CASH FLOWS FROM FINANCING ACTIVITIES:
Tax benefit from share-based compensation	451	363	3,239	2,446
Revolving credit borrowings		(40,000)
Net cost of junior subordinated debt securities redemption				(329,897)
Net proceeds from issuance of senior notes			400,000
Net cash provided by (used in) financing activities	451	(39,637)	403,239	(327,451)
EFFECT OF EXCHANGE RATE CHANGES ON CASH	(7,000)	(9,240)	1,575	(23,945)
Net increase (decrease) in cash	48,385	115,241	(41,389)	59,153
Cash, beginning of period	227,033	291,632	316,807	347,720
Cash, end of period	275,418	406,873	275,418	406,873
SUPPLEMENTAL CASH FLOW INFORMATION:
Income taxes paid (recovered)	45,202	(4,345)	129,608	49,050
Interest paid		$ 72	$ 14,719	$ 23,054