Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Operating activities
Net earnings	$ 176,077	$ 116,468
Adjustments to reconcile net earnings to net cash provided by operating activities
Change in premium, claims and other receivables	(68,083)	(103,245)
Change in reinsurance recoverables	2,921	(84,728)
Change in ceded unearned premium	(32,951)	36,870
Change in loss and loss adjustments expense payable	84,925	147,870
Change in unearned premium	116,448	63,015
Change in reinsurance, premium and claims payable, excluding restricted cash	3,290	(30,413)
Change in accounts payable and accrued liabilities	(44,867)	(19,426)
Stock-based compensation expense	6,168	7,137
Depreciation and amortization expense	9,133	8,769
Other, net	(8,510)	(20,533)
Cash provided by operating activities	244,551	121,784
Investing activities
Proceeds from sales of available for sale fixed maturity securities	218,572	246,331
Proceeds from sale of equity securities	1,739
Maturity or call of available for sale fixed maturity securities	325,046	285,637
Maturity or call of held to maturity fixed maturity securities	28,579	24,932
Cost of available for sale fixed maturity securities acquired	(628,278)	(835,368)
Cost of equity securities acquired	94,706
Cost of other investments acquired	0	(27,784)
Change in short-term investments	(62,621)	292,365
Payments for purchase of businesses, net of cash received	(32,143)	(1,892)
Other, net	(6,982)	(10,942)
Cash used by investing activities	(250,794)	(26,721)
Financing activities
Advances on line of credit	140,000	95,000
Payments on line of credit	(28,000)
Sale of common stock	13,644	35,236
Purchase of common stock	(126,442)	(200,302)
Dividends paid	(32,002)	(33,305)
Other, net	(2,323)	(2,307)
Cash used by financing activities	(35,123)	(105,678)
Net decrease in cash	(41,366)	(10,615)
Cash at beginning of year	104,550	97,857
Cash at end of period	$ 63,184	$ 87,242