Consolidated Statements of Changes in Stockholders’ Equity (Unaudited) (USD $) In Thousands	Outstanding Common Shares Repurchased [Member] Treasury Stock [Member]	Shares Repurchased To Fund Options Exercised [Member] Treasury Stock [Member]	Shares Repurchased To Satisfy Tax Obligations [Member] Treasury Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance, beginning of period at Dec. 31, 2010				$ 313	$ 189,348		$ 204,128	$ (3,744)
Repurchase of outstanding shares			(209)
Change in net unrealized gains (losses) on securities available for sale, net of taxes of approximately ($962) and $2,756 for the three months ended March 31, 2012 and 2011, respectively								(3,490)	(3,490)
Amortization of actuarial losses, net of taxes of approximately ($117) and ($61) for the three months ended March 31, 2012 and 2011, respectively								77	77
Amortization of prior service credits, net of taxes of approximately $5 for the three months ended March 31, 2012 and 2011								(6)	(6)
OTTI charges included in income, net of taxes of approximately ($408) for the three months ended March 31, 2011								518	518
Net income							7,953		7,953
Cash dividends declared and paid on common shares ($0.13 per common share for the three months ended March 31, 2012 and 2011)							(3,995)
Award of common shares released from Employee Benefit Trust (146,735 and 131,799 common shares for the three months ended March 31, 2012 and 2011, respectively)					1,429
Issuance upon exercise of stock options					348	209	(32)
Stock-based compensation activity, net					405
Stock-based income tax benefit					80
Shares issued upon vesting of restricted stock unit awards				1	724
Balance, end of period at Mar. 31, 2011				314	192,334		208,054	(6,645)	394,057
Balance, beginning of period at Dec. 31, 2011				315	195,628	(7,355)	223,510	4,813	416,911
Repurchase of outstanding shares	(1,282)	(548)	(370)
Change in net unrealized gains (losses) on securities available for sale, net of taxes of approximately ($962) and $2,756 for the three months ended March 31, 2012 and 2011, respectively								1,217	1,217
Amortization of actuarial losses, net of taxes of approximately ($117) and ($61) for the three months ended March 31, 2012 and 2011, respectively								149	149
Amortization of prior service credits, net of taxes of approximately $5 for the three months ended March 31, 2012 and 2011								(6)	(6)
Net income							7,129		7,129
Cash dividends declared and paid on common shares ($0.13 per common share for the three months ended March 31, 2012 and 2011)							(3,965)
Award of common shares released from Employee Benefit Trust (146,735 and 131,799 common shares for the three months ended March 31, 2012 and 2011, respectively)					1,363
Issuance upon exercise of stock options					73	802	(24)
Stock-based compensation activity, net					4
Stock-based income tax benefit					106
Shares issued upon vesting of restricted stock unit awards					151	1,343	(97)
Balance, end of period at Mar. 31, 2012				$ 315	$ 197,325	$ (7,410)	$ 226,553	$ 6,173	$ 422,956