CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2014	$ 361,296	$ 96,121	$ 263,345	$ 3,830	$ (2,000)
Balance (in shares) at Dec. 31, 2014		24,698,432
Comprehensive income:
Net income	22,516		22,516
Other comprehensive income (loss), net of tax	(1,108)			(1,108)
Cash dividends declared	(7,560)		(7,560)
Treasury shares purchased under deferred directors' plan	0	$ 213			(213)
Treasury shares purchased under deferred directors' plan (in shares)		(7,932)
Stock activity under equity compensation plans	(390)	$ (390)
Stock activity under equity compensation plans (in shares)		101,796
Stock based compensation expense	921	$ 921
Balance at Jun. 30, 2015	375,675	$ 96,865	278,301	2,722	(2,213)
Balance (in shares) at Jun. 30, 2015		24,792,296
Balance at Dec. 31, 2015	392,812	$ 99,123	294,002	2,142	(2,455)
Balance (in shares) at Dec. 31, 2015		24,819,066
Comprehensive income:
Net income	25,082		25,082
Other comprehensive income (loss), net of tax	8,024			8,024
Cash dividends declared	(8,767)		(8,767)
Treasury shares purchased under deferred directors' plan	0	$ 226			(226)
Treasury shares purchased under deferred directors' plan (in shares)		(7,613)
Stock activity under equity compensation plans	(143)	$ (143)
Stock activity under equity compensation plans (in shares)		82,775
Stock based compensation expense	1,796	$ 1,796
Balance at Jun. 30, 2016	$ 418,804	$ 101,002	$ 310,317	$ 10,166	$ (2,681)
Balance (in shares) at Jun. 30, 2016		24,894,228