Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
CASH FROM (USED IN) OPERATING ACTIVITIES:
Net income to common stockholders	$ 116,615	$ 135,318
Adjustments to reconcile net income to net cash from operating activities:
Net investment gains	(19,969)	(47,491)
Depreciation and amortization	20,910	22,212
Noncontrolling interests	(17)	(86)
Investment funds	(10,934)	(27,624)
Stock incentive plans	4,989	7,447
Change in:
Arbitrage trading account	4,485	(2,946)
Premiums and fees receivable	(76,268)	(97,077)
Reinsurance accounts	(34,039)	(16,857)
Deferred policy acquisition costs	(23,608)	(11,483)
Deferred income taxes	22,471	48,160
Reserves for losses and loss expenses	84,569	47,443
Unearned premiums	174,229	115,434
Other liabilities	(148,321)	(98,688)
Net cash from (used in) operating activities	115,112	73,762
CASH FROM (USED IN) INVESTING ACTIVITIES:
Proceeds from sale of fixed matuirty securities	463,388	295,134
Proceeds from sale of equity securities	38,248	32,575
Distributions from (contributions to) investment funds	(22,072)	24,744
Proceeds from maturities and prepayments of fixed maturity securities	667,711	408,647
Purchase of fixed maturity securities	(896,378)	(872,588)
Purchase of equity securities	(35,486)	(68,652)
Real estate purchased	(10,301)	(5,611)
Change in loans receivable	(53,405)	(93,934)
Net additions to real estate, furniture and equipment	(13,042)	(15,055)
Change in balances due to security brokers	43,325	16,146
Payment for business purchased, net of cash acquired	(38,556)	0
Net cash from (used in) investing activities	143,432	(278,594)
CASH FROM (USED IN) FINANCING ACTIVITIES:
Net proceeds from issuance of debt	0	354,315
Net proceeds from stock options exercised	0	3,428
Repayment of debt	(206,280)	(1,684)
Other, net	7,638	10,446
Net cash from (used in) financing activities	(198,642)	366,505
Net impact on cash due to change in foreign exchange rates	(20,080)	8,992
Net change in cash and cash equivalents	39,822	170,665
Cash and cash equivalents at beginning of year	905,670	911,742
Cash and cash equivalents at end of period	$ 945,492	$ 1,082,407