Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (USD $) In Thousands, except Share data	Total USD ($)		Common Shares Outstanding	Accumulated Other Comprehensive (Loss) Income USD ($)	Common Stock USD ($)	Additional Paid-in Capital USD ($)	Retained Earnings USD ($)	Treasury Stock USD ($)
Beginning balance at Dec. 31, 2010	$ 266,224			$ (6,766)	$ 91,332	$ 59,080	$ 151,978	$ (29,400)
Beginning balance, shares at Dec. 31, 2010			16,648,303
Net income	13,622						13,622
Other comprehensive income, net of taxes	4,515			4,515
Cash dividends declared ($0.60 per share)	(10,043)						(10,043)
Stock issued under dividend reinvestment and employee stock purchase plans and other employee benefit programs	1,787					62	13	1,712
Stock issued under dividend reinvestment and employee stock purchase plans and other employee benefit programs, shares			105,345
Purchases of treasury stock, shares			(85,285)
Purchases of treasury stock	(1,209)							(1,209)
Restricted stock awards granted, shares			58,736
Restricted stock awards granted						(1,019)	47	972
Vesting of restricted stock awards	203					203
Ending balance at Sep. 30, 2011	275,099			(2,251)	91,332	58,326	155,617	(27,925)
Ending balance, shares at Sep. 30, 2011			16,727,099
Beginning balance at Dec. 31, 2011	272,979	[1]		(6,101)	91,332	58,495	157,566	(28,313)
Beginning balance, shares at Dec. 31, 2011			16,702,376
Net income	15,796						15,796
Other comprehensive income, net of taxes	1,966			1,966
Cash dividends declared ($0.60 per share)	(10,058)						(10,058)
Stock issued under dividend reinvestment and employee stock purchase plans and other employee benefit programs	1,987						(64)	2,051
Stock issued under dividend reinvestment and employee stock purchase plans and other employee benefit programs, shares			121,012
Cancelled stock options and awards, shares			(13,125)
Cancelled stock options and awards	33					300	(54)	(213)
Tax expense on stock based compensation	(84)					(84)
Purchases of treasury stock, shares			(116,294)
Purchases of treasury stock	(1,877)							(1,877)
Restricted stock awards granted, shares			71,157
Restricted stock awards granted						(1,154)	(134)	1,288
Vesting of restricted stock awards	847					847
Ending balance at Sep. 30, 2012	$ 281,589			$ (4,135)	$ 91,332	$ 58,404	$ 163,052	$ (27,064)
Ending balance, shares at Sep. 30, 2012			16,765,126

[1] Note: The consolidated balance sheet at December 31, 2011 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by U. S. generally accepted accounting principles for complete financial statements. Certain amounts have been reclassified to conform to the current-year presentation. See accompanying notes to the unaudited consolidated financial statements.