Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 38,926	$ 115,944
Adjustments to reconcile net income to net cash provided by operating activities:
Decrease (increase) in premiums receivable	38,549	(78,969)
Decrease (increase) in funds held by reinsureds, net	3,817	(4,707)
Decrease (increase) in reinsurance receivables	(56,106)	(68,311)
Decrease (increase) in income taxes	6,546	31,408
Decrease (increase) in prepaid reinsurance premiums	15,994	15,016
Increase (decrease) in reserve for losses and loss adjustment expenses	29,962	20,927
Increase (decrease) in unearned premiums	(33,573)	(28,224)
Increase (decrease) in other net payable to reinsurers	(106,588)	(52,400)
Increase (decrease) in losses in course of payment	17,456	60,419
Change in equity adjustments in limited partnerships	2,514	(7,173)
Distribution of limited partnership income	9,859	7,369
Change in other assets and liabilities, net	24,496	35,494
Non-cash compensation expense	3,117	1,946
Amortization of bond premium (accrual of bond discount)	4,541	4,955
Amortization of underwriting discount on senior notes	1	1
Net realized capital (gains) losses	66,377	(21,296)
Net cash provided by (used in) operating activities	65,888	32,399
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from fixed maturities matured/called - available for sale, at market value	154,378	188,815
Proceeds from fixed maturities sold - available for sale, at market value	188,046	112,846
Proceeds from fixed maturities sold - available for sale, at fair value		1,236
Proceeds from equity securities sold - available for sale, at fair value	86,149	133,960
Distributions from other invested assets	255,889	10,797
Cost of fixed maturities acquired - available for sale, at market value	(506,085)	(293,848)
Cost of equity securities acquired - available for sale, at fair value	(92,019)	(164,112)
Cost of other invested assets acquired	(413,223)	(16,600)
Net change in short-term investments	235,895	(860)
Net change in unsettled securities transactions	5,870	(31,296)
Net cash provided by (used in) investing activities	(85,100)	(59,062)
CASH FLOWS FROM FINANCING ACTIVITIES:
Tax benefit from share-based compensation	1,676	2,020
Net cash provided by (used in) financing activities	1,676	2,020
EFFECT OF EXCHANGE RATE CHANGES ON CASH	10,546	(31,845)
Net increase (decrease) in cash	(6,990)	(56,488)
Cash, beginning of period	155,429	323,975
Cash, end of period	148,439	267,487
SUPPLEMENTAL CASH FLOW INFORMATION:
Income taxes paid (recovered)	$ 4,558	$ 18,077