Consolidated Statements of Changes in Stockholders’ Equity (USD $) In Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member] Purchase of Common Shares Outstanding [Member]	Treasury Stock [Member] Restricted Stock Awards Repurchased To Satisfy Tax Obligations [Member]	Treasury Stock [Member] Shares Purchased To Fund Options Exercised [Member]	Treasury Stock [Member]	Unearned Compensation [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance at Dec. 31, 2009	$ 311	$ 185,842				$ (36)	$ (575)	$ 181,181	$ (6,579)
Value of shares purchased for the Treasury				(347)	(370)
Amortization of prior service credits, net of taxes of $20 for each of the years ended December 31, 2012, 2011 and 2010, respectively									(25)	25
Amortization of net actuarial losses, net of taxes of ($456), ($243)and ($140) for the years ended December 31, 2012, 2011 and 2010, respectively									175	175
Unrecognized actuarial losses, net of taxes $340, $1,932 and $513 for years ended December 31, 2012, 2011 and 2010, respectively									(715)	(715)
Change in net unrealized gains on securities available for sale, net of taxes of approximately ($5,259), ($7,706) and ($1,810) for the years ended December 31, 2012, 2011 and 2010, respectively									2,249	2,249
Reclassification adjustment for losses included in net income, net of taxes of approximately ($318), ($692)and ($904) for the years ended December 31, 2012, 2011 and 2010, respectively									1,151	6
Net income								38,835		38,835
Value of release of shares from Employee Benefit Trust		1,167					575
Value of stock options exercised	1	446				515		(92)		370
Stock-based compensation activity, net		487
Stock-based income tax (provision) benefit		12
Value of shares issued upon vesting of restricted stock unit awards	1	1,394				238		(8)
Cash dividends declared and paid on common shares ($0.52 per share for each of the years ended December 31, 2012, 2011 and 2010, respectively)								(15,788)
Balance at Dec. 31, 2010	313	189,348						204,128	(3,744)	390,045
Value of shares purchased for the Treasury			(7,316)	(406)	(54)
Amortization of prior service credits, net of taxes of $20 for each of the years ended December 31, 2012, 2011 and 2010, respectively									(25)	25
Amortization of net actuarial losses, net of taxes of ($456), ($243)and ($140) for the years ended December 31, 2012, 2011 and 2010, respectively									311	311
Unrecognized actuarial losses, net of taxes $340, $1,932 and $513 for years ended December 31, 2012, 2011 and 2010, respectively									(2,505)	(2,505)
Change in net unrealized gains on securities available for sale, net of taxes of approximately ($5,259), ($7,706) and ($1,810) for the years ended December 31, 2012, 2011 and 2010, respectively									9,890	9,890
Reclassification adjustment for losses included in net income, net of taxes of approximately ($318), ($692)and ($904) for the years ended December 31, 2012, 2011 and 2010, respectively									886
Net income								35,348		35,348
Value of release of shares from Employee Benefit Trust		1,541
Value of stock options exercised	1	1,825				326		(50)		54
Stock-based compensation activity, net		954
Stock-based income tax (provision) benefit		292
Value of shares issued upon vesting of restricted stock unit awards	1	1,668				95		(6)
Cash dividends declared and paid on common shares ($0.52 per share for each of the years ended December 31, 2012, 2011 and 2010, respectively)								(15,910)
Balance at Dec. 31, 2011	315	195,628				(7,355)		223,510	4,813	416,911
Value of shares purchased for the Treasury			(5,019)	(532)	(906)
Amortization of prior service credits, net of taxes of $20 for each of the years ended December 31, 2012, 2011 and 2010, respectively									(26)	26
Amortization of net actuarial losses, net of taxes of ($456), ($243)and ($140) for the years ended December 31, 2012, 2011 and 2010, respectively									587	587
Unrecognized actuarial losses, net of taxes $340, $1,932 and $513 for years ended December 31, 2012, 2011 and 2010, respectively									(479)	(479)
Change in net unrealized gains on securities available for sale, net of taxes of approximately ($5,259), ($7,706) and ($1,810) for the years ended December 31, 2012, 2011 and 2010, respectively									6,831	6,831
Reclassification adjustment for losses included in net income, net of taxes of approximately ($318), ($692)and ($904) for the years ended December 31, 2012, 2011 and 2010, respectively									411	(26)
Net income								34,331		34,331
Value of release of shares from Employee Benefit Trust		1,480
Value of stock options exercised		164				1,818		(63)		905
Stock-based compensation activity, net		1,028
Stock-based income tax (provision) benefit		(303)
Value of shares issued upon vesting of restricted stock unit awards		317				1,737		(105)
Cash dividends declared and paid on common shares ($0.52 per share for each of the years ended December 31, 2012, 2011 and 2010, respectively)								(15,817)
Balance at Dec. 31, 2012	$ 315	$ 198,314				$ (10,257)		$ 241,856	$ 12,137	$ 442,365