Consolidated Statements of Changes in Stockholders’ Equity (Unaudited) (USD $) In Thousands	Shares Repurchased To Satisfy Tax Obligations [Member] Treasury Stock [Member]	Shares Repurchased To Pay For Option Exercise [Member] Treasury Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Unearned Compensation [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance, beginning of period at Dec. 31, 2009			$ 311	$ 185,842	$ (36)	$ (575)	$ 181,181	$ (6,579)
Repurchase of shares	(347)	(370)
Change in net unrealized gains on securities available for sale, net of taxes of approximately ($8,707) and ($8,548) for the nine months ended September 30, 2011 and 2010, respectively								10,710	10,710
Amortization of actuarial losses, net of taxes of approximately ($183) and ($103) for the nine months ended September 30, 2011 and 2010, respectively								129	129
Amortization of prior service credits, net of taxes of approximately $15 and $13 for the nine months ended September 30, 2011 and 2010, respectively								(16)	(16)
OTTI charges included in income, net of taxes of approximately ($693) and ($683)for the nine months ended September 30, 2011 and 2010, respectively								855	855
Reclassification adjustment for gains included in net income, net of taxes of approximately $28 for the nine months ended September 30, 2010								(34)	(34)
Net income							30,286		30,286
Cash dividends declared and paid on common shares ($0.39 per common share for the nine months ended September 30, 2011 and 2010, respectively)							(11,840)
Award of common shares released from Employee Benefit Trust				1,131		491
Issuance upon exercise of stock options				208	515		(92)
Stock-based compensation activity, net				112
Stock-based income tax benefit (expense)				(14)
Shares issued upon vesting of restricted stock unit awards			1	1,394	238		(8)
Balance, end of period at Sep. 30, 2010			312	188,673		(84)	199,527	5,065	379,617
Balance, beginning of period at Dec. 31, 2010			313	189,348			204,128	(3,744)	390,045
Repurchase of shares	(376)	(54)			(4,132)
Change in net unrealized gains on securities available for sale, net of taxes of approximately ($8,707) and ($8,548) for the nine months ended September 30, 2011 and 2010, respectively								11,137	11,137
Amortization of actuarial losses, net of taxes of approximately ($183) and ($103) for the nine months ended September 30, 2011 and 2010, respectively								233	233
Amortization of prior service credits, net of taxes of approximately $15 and $13 for the nine months ended September 30, 2011 and 2010, respectively								(19)	(19)
OTTI charges included in income, net of taxes of approximately ($693) and ($683)for the nine months ended September 30, 2011 and 2010, respectively								885	885
Net income							27,177		27,177
Cash dividends declared and paid on common shares ($0.39 per common share for the nine months ended September 30, 2011 and 2010, respectively)							(11,973)
Award of common shares released from Employee Benefit Trust				1,505
Issuance upon exercise of stock options			1	1,825	324		(50)
Stock-based compensation activity, net				532
Stock-based income tax benefit (expense)				260
Shares issued upon vesting of restricted stock unit awards			1	1,668	3
Balance, end of period at Sep. 30, 2011			$ 315	$ 195,138	$ (4,235)		$ 219,282	$ 8,492	$ 418,992