Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2013	14,609
Balance at Dec. 31, 2013	$ 9,581	$ 33,255	$ 188,825	$ (2,217)	$ 229,444
Net income			34,822		34,822
Other comprehensive income, net of tax				4,302	4,302
Stock compensation expense		2,016			2,016
Stock issued for exercise of stock options, net of withholdings to satisfy employee tax obligations (in shares)	108
Stock issued for exercise of stock options, net of withholdings to satisfy employee tax obligations	$ 359	2,426	(114)		2,671
Shares issued for non-vested restricted stock (in shares)	40
Shares issued for non-vested restricted stock	$ 133	1,022	(1,155)
Stock issued for share-based awards, net of withholdings to satisfy employee employee tax obligations (in shares)	5
Stock issued for share-based awards, net of withholdings to satisfy employee employee tax obligations	$ 18	(112)			(94)
Cash dividends declared, $0.59 per share			(12,924)		(12,924)
Shares repurchased and cancelled (in shares)	(17)
Shares repurchased and cancelled	$ (56)	(416)	130		(342)
Balance (in shares) at Dec. 31, 2014	14,745
Balance at Dec. 31, 2014	$ 10,035	38,191	209,584	2,085	259,895
Net income			37,187		37,187
Other comprehensive income, net of tax				(1,453)	(1,453)
Stock compensation expense		2,134			2,134
Stock issued for exercise of stock options, net of withholdings to satisfy employee tax obligations (in shares)	126
Stock issued for exercise of stock options, net of withholdings to satisfy employee tax obligations	$ 418	3,129	(220)		3,327
Shares issued for non-vested restricted stock (in shares)	35
Shares issued for non-vested restricted stock	$ 117	1,099	(1,216)
Stock issued for share-based awards, net of withholdings to satisfy employee employee tax obligations (in shares)	18
Stock issued for share-based awards, net of withholdings to satisfy employee employee tax obligations	$ 61	(256)	(128)		(323)
Cash dividends declared, $0.59 per share			(14,248)		(14,248)
Shares repurchased and cancelled (in shares)	(5)
Shares repurchased and cancelled	$ (15)	(117)	132
Balance (in shares) at Dec. 31, 2015	14,919
Balance at Dec. 31, 2015	$ 10,616	44,180	231,091	632	286,519
Net income			41,027		41,027
Other comprehensive income, net of tax				(2,131)	(2,131)
Stock compensation expense		2,473			2,473
Stock issued for exercise of stock options, net of withholdings to satisfy employee tax obligations (in shares)	157
Stock issued for exercise of stock options, net of withholdings to satisfy employee tax obligations	$ 521	4,623	(2,286)		2,858
Shares issued for non-vested restricted stock (in shares)	34
Shares issued for non-vested restricted stock	$ 114	1,204	(1,318)
Stock issued for share-based awards, net of withholdings to satisfy employee employee tax obligations (in shares)	23
Stock issued for share-based awards, net of withholdings to satisfy employee employee tax obligations	$ 76	(610)	(200)		(734)
Cash dividends declared, $0.59 per share			(16,140)		(16,140)
Shares repurchased and cancelled (in shares)	(10)
Shares repurchased and cancelled	$ (33)	(232)	265
Balance (in shares) at Dec. 31, 2016	22,617
Balance at Dec. 31, 2016	$ 36,250	26,682	252,439	(1,499)	313,872
3 for 2 stock split (in shares)	7,494
3 for 2 stock split	$ 24,956	$ (24,956)