Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2012		55,486,651
Balance at Dec. 31, 2012	$ 322,052	$ 55	$ 419,618	$ (97,436)	$ (185)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in foreign currency translation adjustment, net of tax	(605)				(605)
Net loss	(15,278)			(15,278)
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of witholding taxes (in shares)		405,328
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes	1,106	$ 1	1,105
Issuance of common stock in connection with employee stock purchase plan (in shares)		86,338
Issuance of common stock in connection with employee stock purchase plan	$ 540		540
Issuance of restricted common stock (in shares)	76,167
Issuance of restricted common stock	$ 0
Stock-based compensation expense	8,286		8,286
Balance (in shares) at Dec. 31, 2013		56,054,484
Balance at Dec. 31, 2013	316,101	$ 56	429,549	(112,714)	(790)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in foreign currency translation adjustment, net of tax	(714)				(714)
Net loss	(26,496)			(26,496)
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of witholding taxes (in shares)		817,634
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes	721	$ 1	720
Issuance of common stock in connection with employee stock purchase plan (in shares)		126,017
Issuance of common stock in connection with employee stock purchase plan	$ 943		943
Issuance of restricted common stock (in shares)	86,205
Issuance of restricted common stock	$ 0
Stock-based compensation expense	10,384		10,384
Balance (in shares) at Dec. 31, 2014		57,084,340
Balance at Dec. 31, 2014	300,939	$ 57	441,596	(139,210)	(1,504)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in foreign currency translation adjustment, net of tax	(2,950)				(2,950)
Net loss	(30,384)			(30,384)
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of witholding taxes (in shares)		1,152,797
Issuance of common stock upon exercise of stock options, vesting of restricted stock units and other, net of withholding taxes	2,020	$ 1	2,019
Issuance of common stock in connection with employee stock purchase plan (in shares)		118,879
Issuance of common stock in connection with employee stock purchase plan	$ 934		934
Issuance of restricted common stock (in shares)	78,448
Issuance of restricted common stock	$ 0
Excess tax benefits from employee stock plans	32		32
Stock-based compensation expense	11,560		11,560
Balance (in shares) at Dec. 31, 2015		58,434,464
Balance at Dec. 31, 2015	$ 282,151	$ 58	$ 456,141	$ (169,594)	$ (4,454)