Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues:
Net premiums earned	$ 2,574,920	$ 2,566,057	$ 2,566,685
Net investment income	131,896	140,947	143,814
Net realized investment gains	66,380	58,397	57,089
Other	10,174	11,884	8,297
Total revenues	2,783,370	2,777,285	2,775,885
Expenses:
Losses and loss adjustment expenses	1,961,448	1,829,205	1,825,766
Policy acquisition costs	477,788	481,721	505,565
Other operating expenses	207,281	215,711	255,358
Other operating expenses	1,543	5,549	6,806
Total expenses	2,648,060	2,532,186	2,593,495
Income before income taxes	135,310	245,099	182,390
Income tax expense	18,399	53,935	30,192
Net income	$ 116,911	$ 191,164	$ 152,198
Net income per share:
Basic (in dollars per share)	$ 2.13	$ 3.49	$ 2.78
Diluted (in dollars per share)	$ 2.13	$ 3.49	$ 2.78