Consolidated Statements of Changes in Stockholders' Equity (USD $) In Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Gain (Loss) [Member]	Employee Stock Ownership Plan [Member]	Treasury Stock [Member]	Common Stock Acquired by Deferred Compensation Plan [Member]	Deferred Compensation Plan Liability [Member]
Beginning Balance at Dec. 31, 2011	$ 216,849		$ 336	$ 262,812	$ 186,666	$ (2,468)	$ (4,193)	$ (226,304)	$ (871)	$ 871
Net income	15,979				15,979
Unrealized gain (loss) on securities (net of tax expense (benefit) $1,949 in 2012 and $(4,876) in 2013)	2,822					2,822
Tax expense of stock plans	(482)			(482)
Stock awards	396			396
Treasury stock allocated to restricted stock plan				(282)	42			240
Purchased shares of common stock (718,253 in 2012 and 533,018 in 2013)	(10,196)							(10,196)
Allocation of ESOP stock	363			146			217
Cash dividend $0.36 in 2012 and $0.36 in 2013 per share	(6,463)				(6,463)
Exercise of stock options	419				(40)			459
Sale of stock for the deferred compensation plan									182	(182)
Ending Balance at Sep. 30, 2012	219,687		336	262,590	196,184	354	(3,976)	(235,801)	(689)	689
Beginning Balance at Dec. 31, 2012	219,792		336	262,704	198,109	49	(3,904)	(237,502)	(647)	647
Net income	14,392				14,392
Unrealized gain (loss) on securities (net of tax expense (benefit) $1,949 in 2012 and $(4,876) in 2013)	(7,060)					(7,060)
Stock awards	509			509
Treasury stock allocated to restricted stock plan				(259)	4			255
Purchased shares of common stock (718,253 in 2012 and 533,018 in 2013)	(8,107)							(8,107)
Allocation of ESOP stock	387			171			216
Cash dividend $0.36 in 2012 and $0.36 in 2013 per share	(6,208)				(6,208)
Exercise of stock options	64				(6)			70
Purchase of stock for the deferred compensation plan									(13)	13
Ending Balance at Sep. 30, 2013	$ 213,769		$ 336	$ 263,125	$ 206,291	$ (7,011)	$ (3,688)	$ (245,284)	$ (660)	$ 660