Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (USD $) In Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss), net of taxes	Treasury stock, at cost
Beginning balance at Dec. 31, 2010		$ 61	$ 367,448	$ 823,579	$ 96,582	$ (407,663)
Options exercised, 2012, 190,897 shares; 2011, 136,290 shares		1
Options exercised and conversion of common stock units and restricted stock units			4,247
Share-based compensation expense			819
Cumulative effect of change in accounting principle, net of taxes				(34,447)	1,531
Net income	13,956			13,953
Cash dividends, 2012, $0.26 per share; 2011, $0.22 per share				(9,094)
Change in net unrealized gains and losses on fixed maturities and equity securities	43,540				43,540
Acquisition of shares, 2012, 705,057 shares; 2011, 60,126 shares						(1,007)
Total shareholders' equity	899,553	62	372,514	793,994	141,653	(408,670)
Ending balance at Jun. 30, 2011	899,553	62	372,514	793,994	141,653	(408,670)
Beginning balance at Dec. 31, 2011	1,055,353	62	373,384	840,644	251,980	(410,717)
Options exercised, 2012, 190,897 shares; 2011, 136,290 shares
Conversion of common stock units, 2012, 10,696 shares; 2011, 15,715 shares
Conversion of restricted stock units, 2012, 85,641 shares; 2011, 170,876 shares
Options exercised and conversion of common stock units and restricted stock units			3,773
Share-based compensation expense			860
Cumulative effect of change in accounting principle, net of taxes
Net income	39,774			39,774
Cash dividends, 2012, $0.26 per share; 2011, $0.22 per share				(10,689)
Change in net unrealized gains and losses on fixed maturities and equity securities	66,422				66,422
Change in net funded status of pension and other postretirement benefit obligations	0
Acquisition of shares, 2012, 705,057 shares; 2011, 60,126 shares						(11,955)
Total shareholders' equity	1,143,538	62	378,017	869,729	318,402	(422,672)
Ending balance at Jun. 30, 2012	$ 1,143,538	$ 62	$ 378,017	$ 869,729	$ 318,402	$ (422,672)