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	$ 237,461	$ 244,570	$ 214,738
Net investment income	9,930	10,729	11,335
Commissions and other income	5,722	6,098	6,911
Net realized gains (losses) on investments, excluding impairment losses	9,899	(15,897)	16,527
Total other-than-temporary impairment losses on investments	(894)	(1,987)	(42)
Portion of other-than-temporary impairment losses recognized in other comprehensive income	6	81	0
Net realized gains (losses) on investments	9,011	(17,803)	16,485
Total revenue	262,124	243,594	249,469
Expenses
Losses and loss expenses incurred	138,088	215,555	145,952
Other operating expenses	77,430	73,328	68,704
Total expenses	215,518	288,883	214,656
Income (loss) before federal income taxes	46,606	(45,289)	34,813
Federal income taxes (benefits)	14,687	(17,114)	9,798
Net income (loss)	$ 31,919	$ (28,175)	$ 25,015
Per share data [Abstract]
Basic and diluted earnings (losses) (in dollars per share)	$ 2.15	$ (1.9)	$ 1.69
Cash dividends paid (in dollars per share)	$ 1.00	$ 1.00	$ 2.25