Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
REVENUES:
Net premiums written	$ 1,376,966	$ 1,203,526
Change in net unearned premiums	(144,847)	(103,875)
Net premiums earned	1,232,119	1,099,651
Net investment income	135,929	157,619
Insurance service fees	26,736	23,877
Net investment gains:
Net realized gains on investment sales	19,969	43,477
Change in valuation allowance, net of other-than-temporary impairments	0	4,014
Net investment gains	19,969	47,491
Revenues from wholly-owned investees	91,735	49,675
Other income	281	392
Total revenues	1,506,769	1,378,705
OPERATING COSTS AND EXPENSES:
Losses and loss expenses	744,679	679,472
Other operating costs and expenses	481,604	431,779
Expenses from wholly-owned investees	89,152	51,330
Interest expense	31,111	28,821
Total operating costs and expenses	1,346,546	1,191,402
Income before income taxes	160,223	187,303
Income tax expense	(43,625)	(52,071)
Net income before noncontrolling interests	116,598	135,232
Noncontrolling interests	17	86
Net income to common stockholders	$ 116,615	$ 135,318
NET INCOME PER SHARE:
Basic	$ 0.86	$ 0.98
Diluted	$ 0.83	$ 0.94