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)	$ 171,686	$ 322,978
Adjustments to reconcile net income to net cash provided by operating activities:
Decrease (increase) in premiums receivable	7,604	(101,728)
Decrease (increase) in funds held by reinsureds, net	60,592	(12,027)
Decrease (increase) in reinsurance receivables	(32,865)	(90,028)
Decrease (increase) in income taxes	(3,883)	14,214
Decrease (increase) in prepaid reinsurance premiums	(10,219)	(12,868)
Increase (decrease) in reserve for losses and loss adjustment expenses	50,497	55,334
Increase (decrease) in future policy benefit reserve	(473)	(127)
Increase (decrease) in unearned premiums	(26,116)	(40,934)
Increase (decrease) in other net payable to reinsurers	5,254	81,172
Increase (decrease) in losses in course of payment	24,473	71,568
Change in equity adjustments in limited partnerships	6,181	(6,762)
Distribution of limited partnership income	15,915	8,600
Change in other assets and liabilities, net	3,844	32,168
Non-cash compensation expense	8,041	5,170
Amortization of bond premium (accrual of bond discount)	12,354	13,333
Amortization of underwriting discount on senior notes	1	1
Net realized capital (gains) losses	74,259	10,505
Net cash provided by (used in) operating activities	367,145	350,569
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from fixed maturities matured/called - available for sale, at market value	503,428	594,807
Proceeds from fixed maturities sold - available for sale, at market value	324,118	355,812
Proceeds from fixed maturities sold - available for sale, at fair value		1,236
Proceeds from equity securities sold - available for sale, at market value	203	83
Proceeds from equity securities sold - available for sale, at fair value	92,245	137,966
Distributions from other invested assets	1,111,710	10,797
Cost of fixed maturities acquired - available for sale, at market value	(1,078,990)	(1,370,458)
Cost of equity securities acquired - available for sale, at market value	(1,105)	(4,464)
Cost of equity securities acquired - available for sale, at fair value	(96,297)	(171,411)
Cost of other invested assets acquired	(1,454,123)	(41,961)
Net change in short-term investments	360,238	222,952
Net change in unsettled securities transactions	30,390	(505)
Net cash provided by (used in) investing activities	(208,183)	(265,146)
CASH FLOWS FROM FINANCING ACTIVITIES:
Common shares issued during the period, net	151	2
Purchase of treasury shares	(85,914)	(75,040)
Dividends paid to shareholders	(48,706)	(42,252)
Net cash provided by (used in) financing activities	(134,469)	(117,290)
EFFECT OF EXCHANGE RATE CHANGES ON CASH	20,792	(7,032)
Net increase (decrease) in cash	45,285	(38,899)
Cash, beginning of period	283,658	437,474
Cash, end of period	328,943	398,575
SUPPLEMENTAL CASH FLOW INFORMATION:
Income taxes paid (recovered)	5,000	24,266
Interest paid	$ 370	$ 132