Unaudited Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
CASH FLOWS PROVIDED BY OPERATING ACTIVITIES:
Net income	$ 176,972	$ 158,992
Adjustments to reconcile net income to cash provided by operating activities:
Net realized gains on sales of investments	(49,756)	(38,533)
Mark to market adjustments	(13,956)	(46,112)
Stock compensation expense	4,240	3,995
Undistributed income of equity method investments	(2,292)	0
Changes in:
Reserve for losses and loss expenses, net of reinsurance recoverables	44,248	5,278
Unearned premiums, net of prepaid reinsurance	241,329	231,824
Insurance balances receivable	(174,899)	(156,967)
Funds held	184,629	(34,212)
Reinsurance balances payable	(12,982)	(17,803)
Net deferred acquisition costs	(40,443)	(34,141)
Net deferred tax assets	521	(2,157)
Accounts payable and accrued liabilities	(83,745)	(70,780)
Other items, net	29,230	14,185
Net cash provided by operating activities	303,096	13,569
CASH FLOWS (USED IN) PROVIDED BY INVESTING ACTIVITIES:
Purchases of trading securities	(1,568,993)	(1,330,735)
Purchases of other invested assets	(779,934)	(54,026)
Sales of trading securities	1,494,648	1,188,307
Sales of other invested assets	663,237	97,989
Purchases of fixed assets	(2,336)	(2,378)
Change in restricted cash	4,823	116,785
Net cash (used in) provided by investing activities	(188,555)	15,942
CASH FLOWS USED IN FINANCING ACTIVITIES:
Dividends paid - partial par value reduction	0	(12,981)
Dividends paid	(16,732)	0
Proceeds from the exercise of stock options	3,030	2,472
Share repurchases	(68,659)	(36,245)
Net cash used in financing activities	(82,361)	(46,754)
Effect of exchange rate changes on foreign currency cash	1,686	(2,055)
NET INCREASE IN CASH AND CASH EQUIVALENTS	33,866	(19,298)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	531,936	681,879
CASH AND CASH EQUIVALENTS, END OF PERIOD	565,802	662,581
Supplemental disclosure of cash flow information:
Cash paid for income taxes	529	6,953
Cash paid for interest expense	$ 18,750	$ 18,750