Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Thousands	Common Stock [Member]	Capital Surplus[Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Beginning balance at Dec. 31, 2010	$ 46,249	$ 103,057	$ 270,905	$ (102,853)	$ (2,497)	$ 314,861
Net income			9,614			9,614
Other comprehensive income					593	593
Cash dividends declared			(5,190)			(5,190)
Stock-based compensation expense, net		(320)		784		464
Exercise of stock options				153		153
Purchase of treasury shares				(9,373)		(9,373)
Ending balance at Mar. 31, 2011	46,249	102,737	275,329	(111,289)	(1,904)	311,122
Beginning balance at Dec. 31, 2011	46,249	103,335	291,050	(125,593)	(3,907)	311,134
Net income			10,031			10,031
Other comprehensive income					2,170	2,170
Cash dividends declared			(5,147)			(5,147)
Stock-based compensation expense, net		(263)		705		442
Exercise of stock options		(113)		601		488
Purchase of treasury shares				(3,072)		(3,072)
Ending balance at Mar. 31, 2012	$ 46,249	$ 102,959	$ 295,934	$ (127,359)	$ (1,737)	$ 316,046