Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
REVENUES:
Net premiums written	$ 1,341,898	$ 1,190,991	$ 2,718,864	$ 2,394,517
Change in net unearned premiums	(59,383)	(43,634)	(204,230)	(147,509)
Net premiums earned	1,282,515	1,147,357	2,514,634	2,247,008
Net investment income	143,737	161,250	279,666	318,869
Insurance service fees	27,652	27,036	54,388	50,913
Net investment gains	33,058	24,286	53,027	67,763
Change in valuation allowance, net of other-than-temporary impairments	0	0	0	4,014
Revenues from wholly-owned investees	83,775	55,434	175,510	105,109
Other income	225	384	506	776
Total revenues	1,570,962	1,415,747	3,077,731	2,794,452
OPERATING COSTS AND EXPENSES:
Losses and loss expenses	805,470	731,202	1,550,149	1,410,674
Other operating costs and expenses	494,286	448,758	975,890	880,537
Expenses from wholly-owned investees	81,293	54,931	170,445	106,261
Interest expense	31,207	32,417	62,318	61,238
Total operating costs and expenses	1,412,256	1,267,308	2,758,802	2,458,710
Income before income taxes	158,706	148,439	318,929	335,742
Income tax expense	(43,579)	(39,535)	(87,204)	(91,606)
Net income before noncontrolling interests	115,127	108,904	231,725	244,136
Noncontrolling interests	830	(66)	847	20
Net income to common stockholders	$ 115,957	$ 108,838	$ 232,572	$ 244,156
NET INCOME PER SHARE:
Basic	$ 0.85	$ 0.79	$ 1.71	$ 1.77
Diluted	$ 0.82	$ 0.76	$ 1.65	$ 1.7