CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Shares	Total
Balance at Dec. 31, 2013	$ 281	$ 104,932	$ 230,478	$ (15,862)	$ 319,829
Balance (in shares) at Dec. 31, 2013	28,056			(1,856)
Issuance of common stock under stock incentive plans		356			356
Issuance of common stock under stock incentive plans (in shares)	49
Issuance of common stock under Employee Stock Purchase Plan		753			753
Issuance of common stock under Employee Stock Purchase Plan (in shares)	35
Stock-based compensation expense		929			929
Nonvested stock awards	$ 1	(1)
Nonvested stock awards (in shares)	59
Shares withheld for taxes paid on stock awards		(578)			(578)
Tax benefit from stock-based compensation		565			565
Dividend payment			(10,527)		(10,527)
Net income			42,681		42,681
Balance at Dec. 31, 2014	$ 282	106,956	262,632	$ (15,862)	354,008
Balance (in shares) at Dec. 31, 2014	28,199			(1,856)
Issuance of common stock under stock incentive plans	$ 1	436			437
Issuance of common stock under stock incentive plans (in shares)	41
Issuance of common stock under Employee Stock Purchase Plan		875			875
Issuance of common stock under Employee Stock Purchase Plan (in shares)	39
Stock-based compensation expense		994			994
Nonvested stock awards	$ 1	(1)
Nonvested stock awards (in shares)	74
Shares withheld for taxes paid on stock awards		(660)			(660)
Tax benefit from stock-based compensation		561			561
Dividend payment			(10,591)		(10,591)
Net income			46,827		46,827
Balance at Dec. 31, 2015	$ 284	109,161	298,868	$ (15,862)	$ 392,451
Balance (in shares) at Dec. 31, 2015	28,353			(1,856)	28,353
Issuance of common stock under stock incentive plans		135			$ 135
Issuance of common stock under stock incentive plans (in shares)	11
Issuance of common stock under Employee Stock Purchase Plan		961			961
Issuance of common stock under Employee Stock Purchase Plan (in shares)	39
Stock-based compensation expense		1,049			1,049
Nonvested stock awards	$ 1	(1)
Nonvested stock awards (in shares)	62
Shares withheld for taxes paid on stock awards		(737)			(737)
Tax benefit from stock-based compensation		513			513
Dividend payment			(9,041)		(9,041)
Net income			48,111		48,111
Balance at Dec. 31, 2016	$ 285	$ 111,081	$ 337,938	$ (15,862)	$ 433,442
Balance (in shares) at Dec. 31, 2016	28,465			(1,856)	28,465