Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Retained Earnings (Accumulated Deficit) [Member]
Beginning balance at Dec. 31, 2015	$ 160,001	$ 51	$ (113,949)	$ 293,003	$ (322)	$ (18,782)
Beginning balance, shares at Dec. 31, 2015		50,927,426	18,887,573
Issuance of common stock from stock options and restricted stock units	4,192	$ 1		4,191
Issuance of common stock from stock options and restricted stock units, shares		1,673,858
Purchase of common stock through stock repurchase program	(7,988)		$ (7,988)
Purchase of common stock through stock repurchase program, shares			980,329
Purchase of common stock through tender offer	(40,794)		$ (40,794)
Purchase of common stock through tender offer, shares			5,237,843
Excess tax benefit and shortfalls — stock options	(2,747)			(2,747)
Stock-based compensation expense	6,852			6,852
Tax withholdings related to net share settlement of RSU’s	(4,446)			(4,446)
Unrealized gain (loss) on investments	(10)				(10)
Unrealized gain (loss) on foreign currency translation	84				84
Net income	2,419					2,419
Ending balance at Dec. 31, 2016	117,563	$ 52	$ (162,731)	296,853	(248)	(16,363)
Ending balance, shares at Dec. 31, 2016		52,601,284	25,105,745
Issuance of common stock from stock options and restricted stock units	942	$ 1		941
Issuance of common stock from stock options and restricted stock units, shares		737,013
Purchase of common stock through stock repurchase program	(8,085)		$ (8,085)
Purchase of common stock through stock repurchase program, shares			749,437
Shelf registration and other fees	(3)			(3)
Stock-based compensation expense	6,912			6,912
Tax withholdings related to net share settlement of RSU’s	(3,940)			(3,940)
Unrealized gain (loss) on investments	13				13
Unrealized gain (loss) on foreign currency translation	300				300
Reclassification for adoption of ASU 2016-09	242					242
Net income	6,803					6,803
Ending balance at Dec. 31, 2017	120,747	$ 53	$ (170,816)	300,763	65	(9,318)
Ending balance, shares at Dec. 31, 2017		53,338,297	25,855,182
Issuance of common stock from stock options and restricted stock units	1,005	$ 1		1,004
Issuance of common stock from stock options and restricted stock units, shares		779,028
Purchase of common stock through stock repurchase program	(7,089)		$ (7,089)
Purchase of common stock through stock repurchase program, shares			471,098
Stock-based compensation expense	8,397			8,397
Tax withholdings related to net share settlement of RSU’s	(3,150)			(3,150)
Unrealized gain (loss) on investments	15				15
Unrealized gain (loss) on foreign currency translation	(295)				(295)
Net income	12,955					12,955
Ending balance at Dec. 31, 2018	$ 132,585	$ 54	$ (177,905)	$ 307,014	$ (215)	$ 3,637
Ending balance, shares at Dec. 31, 2018		54,117,325	26,326,280