Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Employee Stock Ownership Plan [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Gain (Loss) [Member]	Treasury Stock [Member]	Common Stock Acquired by Deferred Compensation Plan [Member]	Deferred Compensation Plan Liability [Member]
Beginning Balance at Dec. 31, 2014	$ 218,259	$ (3,330)	$ 336	$ 265,260	$ 217,714	$ (7,109)	$ (254,612)	$ (304)	$ 304
Net income	10,395				10,395
Other comprehensive income, net of tax	522					522
Tax benefit (expense) of stock plans	8			8
Stock awards	638			638
Treasury stock allocated to restricted stock plan				1,197	(139)		(1,058)
Purchased 259,940 shares of common stock	(4,452)						(4,452)
Allocation of ESOP stock	288	143		145
Cash dividend	(4,288)				(4,288)
Exercise of stock options	165				(38)		203
Sale/Purchase of stock for the deferred compensation plan								(5)	5
Ending Balance at Jun. 30, 2015	221,535	(3,187)	336	267,248	223,644	(6,587)	(259,919)	(309)	309
Beginning Balance at Dec. 31, 2015	238,446	(3,045)	336	269,757	229,140	(6,241)	(251,501)	(314)	314
Net income	7,866				7,866
Other comprehensive income, net of tax	443					443
Tax benefit (expense) of stock plans	(260)			(260)
Stock awards	756			756
Treasury stock allocated to restricted stock plan				1,108	(114)		(994)
Issued 8,282,296 treasury shares to finance acquisition	165,901			36,940			128,961
Allocation of ESOP stock	301	142		159
Cash dividend	(5,481)				(5,481)
Exercise of stock options	1,286				(516)		1,802
Sale/Purchase of stock for the deferred compensation plan								6	(6)
Ending Balance at Jun. 30, 2016	$ 409,258	$ (2,903)	$ 336	$ 308,460	$ 230,895	$ (5,798)	$ (121,732)	$ (308)	$ 308