Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
CASH FROM (USED IN) OPERATING ACTIVITIES:
Net income to common stockholders	$ 169,673	$ 116,615
Adjustments to reconcile net income to net cash from operating activities:
Net investment gains	(52,754)	(19,969)
Depreciation and amortization	25,236	20,910
Noncontrolling interests	11	(17)
Investment funds	(58,906)	(10,934)
Stock incentive plans	6,187	4,989
Change in:
Arbitrage trading account	42	4,485
Premiums and fees receivable	(99,306)	(76,268)
Reinsurance accounts	(49,583)	(34,039)
Deferred policy acquisition costs	(24,066)	(23,608)
Income taxes	70,070	22,471
Reserves for losses and loss expenses	148,204	84,569
Unearned premiums	198,933	174,229
Other	(190,577)	(148,321)
Net cash from operating activities	143,164	115,112
CASH FROM (USED IN) INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	328,371	463,388
Proceeds from sale of equity securities	6,457	38,248
Distributions from (contributions to) investment funds	158,808	(22,072)
Proceeds from maturities and prepayments of fixed maturity securities	546,838	667,711
Purchase of fixed maturity securities	(1,131,612)	(896,378)
Purchase of equity securities	(19,274)	(35,486)
Real estate purchased	(35,613)	(10,301)
Change in loans receivable	(29,568)	(53,405)
Net additions to property, furniture and equipment	(9,862)	(13,042)
Change in balances due to security brokers	51,557	43,325
Payment for business purchased, net of cash acquired	(97)	(38,556)
Net cash from (used in) investing activities	(133,995)	143,432
CASH USED IN FINANCING ACTIVITIES:
Repayment of senior notes and other debt	(125)	(206,280)
Net proceeds from options exercised	53	0
Cash dividends to common stockholders	(12,775)	0
Purchase of common treasury shares	(192,668)	0
Other, net	1,624	7,638
Net cash used in financing activities	(203,891)	(198,642)
Net impact on cash due to change in foreign exchange rates	(1,441)	(20,080)
Net change in cash and cash equivalents	(196,163)	39,822
Cash and cash equivalents at beginning of year	839,738	905,670
Cash and cash equivalents at end of period	$ 643,575	$ 945,492