Consolidated Statements of Changes in Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Shares Outstanding	Accumulated Other Comprehensive (Loss) Income	Additional Paid-in Capital	Retained Earnings	Treasury Stock
Beginning balance at Dec. 31, 2008	$ 203,207	$ 74,370	$ (8,619)	$ 22,459	$ 151,816	$ (36,819)
Beginning balance, shares at Dec. 31, 2008		12,938,514
comprehensive income:
Net income	10,780				10,780
Other comprehensive income (loss), net of income tax (benefit)
Unrealized gain on investment securities available-for-sale	3,092		3,092
Unrealized gain (loss) on swap	1,299		1,299
Unrecognized pension benefits and costs	3,704		3,704
Total comprehensive income	18,875
Cash dividends declared ($0.80 per share)	(11,786)				(11,786)
Stock issued under dividend reinvestment and employee stock purchase plans and other employee benefit programs, shares		95,973
Stock issued under dividend reinvestment and employee stock purchase plans and other employee benefit programs	2,058			27	(344)	2,375
Issuance of common stock, shares		3,392,500
Issuance of common stock	55,597	16,962		38,635
Exercise of stock options, shares		2,547
Exercise of stock options	47			(10)	(3)	60
Cancelled stock options and awards	46				46
Purchases of treasury stock, shares		(11,642)
Purchases of treasury stock	(370)					(370)
Restricted stock awards granted, shares		47,191
Restricted stock awards granted				(1,118)	(2)	1,120
Vesting of restricted stock awards	133			133
Ending balance at Dec. 31, 2009	267,807	91,332	(524)	60,126	150,507	(33,634)
Ending balance, shares at Dec. 31, 2009		16,465,083
comprehensive income:
Net income	15,756				15,756
Other comprehensive income (loss), net of income tax (benefit)
Unrealized gain on investment securities available-for-sale	(4,489)		(4,489)
Unrealized gain (loss) on swap	(830)		(830)
Unrecognized pension benefits and costs	(923)		(923)
Total comprehensive income	9,514
Cash dividends declared ($0.80 per share)	(13,284)				(13,284)
Stock issued under dividend reinvestment and employee stock purchase plans and other employee benefit programs, shares		123,750
Stock issued under dividend reinvestment and employee stock purchase plans and other employee benefit programs	2,189				(605)	2,794
Purchases of treasury stock, shares		(8,512)
Purchases of treasury stock	(153)					(153)
Restricted stock awards granted, shares		67,982
Restricted stock awards granted	(9)			(1,206)	(396)	1,593
Vesting of restricted stock awards	160			160
Ending balance at Dec. 31, 2010	266,224	91,332	(6,766)	59,080	151,978	(29,400)
Ending balance, shares at Dec. 31, 2010		16,648,303
comprehensive income:
Net income	18,882				18,882
Other comprehensive income (loss), net of income tax (benefit)
Unrealized gain on investment securities available-for-sale	6,422		6,422
Unrealized gain (loss) on swap	(1,252)		(1,252)
Unrecognized pension benefits and costs	(4,505)		(4,505)
Total comprehensive income	19,547
Cash dividends declared ($0.80 per share)	(13,382)				(13,382)
Stock issued under dividend reinvestment and employee stock purchase plans and other employee benefit programs, shares		141,485
Stock issued under dividend reinvestment and employee stock purchase plans and other employee benefit programs	2,287			65	13	2,209
Cancelled stock options and awards	28			166	28	(166)
Cancelled stock options and awards, shares		(8,654)
Purchases of treasury stock, shares		(137,494)
Purchases of treasury stock	(1,928)					(1,928)
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 Dec. 31, 2011	$ 272,979	$ 91,332	$ (6,101)	$ 58,495	$ 157,566	$ (28,313)
Ending balance, shares at Dec. 31, 2011		16,702,376