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, 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	12,279		12,279
Other comprehensive income (loss), net of tax	5,221			5,221
Cash dividends declared	(4,079)		(4,079)
Treasury shares purchased under deferred directors' plan	0	$ 198			(198)
Treasury shares purchased under deferred directors' plan (in shares)		(6,723)
Stock activity under equity compensation plans	(143)	$ (143)
Stock activity under equity compensation plans (in shares)		82,775
Stock based compensation expense	784	$ 784
Balance at Mar. 31, 2016	406,874	$ 99,962	302,202	7,363	(2,653)
Balance (in shares) at Mar. 31, 2016		24,895,118
Balance at Dec. 31, 2016	426,978	$ 104,405	327,873	(2,387)	(2,913)
Balance (in shares) at Dec. 31, 2016		24,937,865
Comprehensive income:
Net income	14,514		14,514
Other comprehensive income (loss), net of tax	485			485
Cash dividends declared	(4,771)		(4,771)
Treasury shares purchased under deferred directors' plan	0	$ 220			(220)
Treasury shares purchased under deferred directors' plan (in shares)		(4,846)
Stock activity under equity compensation plans	(1,652)	$ (1,652)
Stock activity under equity compensation plans (in shares)		84,672
Stock based compensation expense	1,559	$ 1,559
Balance at Mar. 31, 2017	$ 437,113	$ 104,532	$ 337,616	$ (1,902)	$ (3,133)
Balance (in shares) at Mar. 31, 2017		25,017,691