Consolidated Statements of Shareholders' Equity (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shareholders' equity at beginning of year	$ 319,061	$ 368,735	$ 372,943
Comprehensive income:
Net income (loss)	31,919	(28,175)	25,015
Other comprehensive income (loss)	9,092	(7,532)	2,449
Other changes affecting shareholders' equity:
Cash dividends paid to shareholders	(14,886)	(14,846)	(33,212)
Issuance of common stock	1,526	879	1,540
Shareholders' equity at end of year:	$ 346,712	$ 319,061	$ 368,735