Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2014		53,000,867		18,139,958
Beginning balance at Dec. 31, 2014	$ 129,106	$ 1	$ 162,641	$ (114,645)	$ 64	$ 81,045
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised and RSUs vested, net of withholdings, Shares		983,525
Stock options exercised and RSUs vested, net of withholdings	1,303		1,303
Stock-based compensation	7,263		7,263
Excess tax benefit from stock-based compensation	6,936		6,936
Purchase of treasury stock (in shares)		(292,200)		(292,200)
Purchase of treasury stock	(7,556)			$ (7,556)
Net income	19,933					19,933
Foreign currency translation adjustments	19				19
Ending balance (in shares) at Dec. 31, 2015		53,692,192		18,432,158
Ending balance at Dec. 31, 2015	157,004	$ 1	178,143	$ (122,201)	83	100,978
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised and RSUs vested, net of withholdings, Shares		421,128
Stock options exercised and RSUs vested, net of withholdings	(1,294)		(1,294)
Stock-based compensation	9,369		9,369
Excess tax benefit from stock-based compensation	1,438		1,438
Purchase of treasury stock (in shares)		(1,788,069)		(1,788,069)
Purchase of treasury stock	(33,746)			$ (33,746)
Net income	17,297					17,297
Foreign currency translation adjustments	820				820
Ending balance (in shares) at Dec. 31, 2016		52,325,251		20,220,227
Ending balance at Dec. 31, 2016	150,888	$ 1	187,656	$ (155,947)	903	118,275
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of applying a change in accounting principle	178		475			(297)
Stock options exercised and RSUs vested, net of withholdings, Shares		644,618
Stock options exercised and RSUs vested, net of withholdings	(2,069)		(2,069)
Stock-based compensation	15,610		15,610
Net income	5,207					5,207
Foreign currency translation adjustments	(2,370)				(2,370)
Ending balance (in shares) at Dec. 31, 2017		52,969,869		20,220,227
Ending balance at Dec. 31, 2017	$ 167,444	$ 1	$ 201,672	$ (155,947)	$ (1,467)	$ 123,185