Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues:
Net premiums earned	$ 2,796,195	$ 2,698,187	$ 2,574,920
Net investment income	125,723	124,538	131,896
Net realized investment gains (losses)	81,184	(11,422)	66,380
Other	8,671	9,738	10,174
Total revenues	3,011,773	2,821,041	2,783,370
Expenses:
Losses and loss adjustment expenses	1,986,122	1,962,690	1,961,448
Policy acquisition costs	526,208	505,517	477,788
Other operating expenses	249,381	219,478	207,281
Other operating expenses	2,637	1,260	1,543
Total expenses	2,764,348	2,688,945	2,648,060
Income before income taxes	247,425	132,096	135,310
Income tax expense	69,476	19,953	18,399
Net income	$ 177,949	$ 112,143	$ 116,911
Net income per share:
Basic (in dollars per share)	$ 3.23	$ 2.04	$ 2.13
Diluted (in dollars per share)	$ 3.23	$ 2.04	$ 2.13