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			19,445			19,445
Other comprehensive income					659	659
Cash dividends declared			(10,319)			(10,319)
Stock-based compensation expense, net		(119)		784		665
Exercise of stock options				153		153
Purchase of treasury shares				(15,085)		(15,085)
Ending balance at Jun. 30, 2011	46,249	102,938	280,031	(117,001)	(1,838)	310,379
Beginning balance at Dec. 31, 2011	46,249	103,335	291,050	(125,593)	(3,907)	311,134
Net income			17,442			17,442
Other comprehensive income					1,430	1,430
Acquisition of Virginia Savings Bancorp		276		7,447		7,723
Cash dividends declared			(10,337)			(10,337)
Stock-based compensation expense, net		(49)		706		657
Exercise of stock options		(113)		601		488
Purchase of treasury shares				(7,915)		(7,915)
Ending balance at Jun. 30, 2012	$ 46,249	$ 103,449	$ 298,155	$ (124,754)	$ (2,477)	$ 320,622