Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues:
Net premiums earned	$ 678,913	$ 646,084	$ 2,017,295	$ 1,919,143
Net investment income	30,857	33,410	93,706	96,569
Net realized investment (losses) gains	16,212	49,752	(7,153)	78,656
Other	2,685	2,532	7,539	7,790
Total revenues	728,667	731,778	2,111,387	2,102,158
Expenses:
Losses and loss adjustment expenses	492,558	467,929	1,446,524	1,415,096
Policy acquisition costs	126,891	121,906	377,006	357,062
Other operating expenses	54,087	50,225	166,165	154,353
Interest	338	388	864	1,176
Total expenses	673,874	640,448	1,990,559	1,927,687
(Loss) income before income taxes	54,793	91,330	120,828	174,471
Income tax (benefit) expense	15,223	25,129	24,061	40,178
Net (loss) income	$ 39,570	$ 66,201	$ 96,767	$ 134,293
Net income per share:
Basic (in dollars per share)	$ 0.72	$ 1.21	$ 1.76	$ 2.45
Diluted (in dollars per share)	$ 0.72	$ 1.21	$ 1.76	$ 2.45
Weighted average shares outstanding:
Basic (in shares)	54,959	54,911	54,941	54,895
Diluted (in shares)	54,973	54,925	54,957	54,918
Dividends paid per share (in dollars per share)	$ 0.6125	$ 0.61	$ 1.8375	$ 1.83