Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities
Net income	$ 215,626	$ 248,099
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of net premium on investments	22,522	29,911
Amortization of intangible assets	6,588	6,768
Net realized and unrealized investment gains	(167,193)	(115,645)
Changes in:
Reinsurance balances, net	(480,517)	(572,301)
Reinsurance recoverable on paid and unpaid losses, net of ceded premiums payable	50,856	45,691
Funds held by reinsured companies and funds held – directly managed	(49,124)	71,350
Deferred acquisition costs	(56,386)	(76,800)
Net tax assets and liabilities	(4,072)	37,445
Unpaid losses and loss expenses including life policy benefits	187,614	80,728
Unearned premiums	359,002	418,493
Other net changes in operating assets and liabilities	6,741	(34,992)
Net cash provided by operating activities	91,657	138,747
Redemptions of fixed maturities	160,065	161,229
Sales and redemptions of short-term investments	44,496	12,692
Purchases of short-term investments	(31,425)	(7,391)
Other, net	(49,036)	(573)
Net cash provided by investing activities	337,791	114,775
Cash flows from financing activities
Dividends paid to common and preferred shareholders	(200,614)	(47,369)
Settlement of share-based awards upon change in control	(75,311)	0
Reissuance of treasury shares, net of taxes	12,938	(4,084)
Repurchase of common shares	0	(71,376)
Net cash used in financing activities	(262,987)	(122,829)
Effect of foreign exchange rate changes on cash	6,293	(30,362)
Increase in cash and cash equivalents	172,754	100,331
Cash and cash equivalents—beginning of period	1,577,097	1,313,468
Cash and cash equivalents—end of period	1,749,851	1,413,799
Supplemental cash flow information:
Taxes paid	16,019	42,257
Interest paid	0	0
Fixed maturities [Member]
Sales of fixed maturities and sales of equities	1,959,793	2,495,633
Purchases of fixed maturities and purchases of equities	(1,851,309)	(2,293,577)
Equities [Member]
Sales of fixed maturities and sales of equities	108,333	120,973
Purchases of fixed maturities and purchases of equities	$ (3,126)	$ (374,211)