Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (loss) [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2015	$ 16	$ 122,932	$ (23,326)	$ (765)	$ 11,087	$ 109,944
Balance, shares at Dec. 31, 2015	11,915,000
Stock option exercises, RSUs vested and related income tax benefit		2,884				2,884
Stock option exercises, RSUs vested and related income tax benefit, shares	458,000
Stock-based compensation expense		1,961				1,961
Purchases of common stock under a stock repurchase program			(3,608)			(3,608)
Purchases of common stock under a stock repurchase program, shares	(406,000)
Net income					17,660	17,660
Other comprehensive income (loss)				126		126
Balance at Dec. 31, 2016	$ 16	127,777	(26,934)	(639)	28,747	128,967
Balance, shares at Dec. 31, 2016	11,967,000
Stock option exercises, RSUs vested and related income tax benefit	$ 1	4,170				4,171
Stock option exercises, RSUs vested and related income tax benefit, shares	705,000
Stock-based compensation expense		2,605				2,605
Purchases of common stock under a stock repurchase program			(11,602)			(11,602)
Purchases of common stock under a stock repurchase program, shares	(892,000)
Forfeiture rate election related to stock-based compensation		94			(94)
Net income					2,595	2,595
Other comprehensive income (loss)				890		890
Balance at Dec. 31, 2017	$ 17	134,646	(38,536)	251	31,248	$ 127,626
Balance, shares at Dec. 31, 2017	11,780,000					11,779,621
Stock option exercises, RSUs vested and related income tax benefit	$ 1	998				$ 999
Stock option exercises, RSUs vested and related income tax benefit, shares	403,000
Stock-based compensation expense		3,059				3,059
Net income					22,773	22,773
Other comprehensive income (loss)				(1,564)		(1,564)
Balance at Dec. 31, 2018	$ 18	$ 138,703	$ (38,536)	$ (1,313)	$ 54,021	$ 152,893
Balance, shares at Dec. 31, 2018	12,183,000					12,183,048