Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive loss
Balance at Dec. 31, 2013	$ 84,852	$ 46	$ 194,930	$ (110,124)
Balances (in shares) at Dec. 31, 2013		46,486,372
Increase (Decrease) in Stockholders' Equity
Issuance of common stock from option exercises	1,190	$ 2	1,188
Issuance of common stock from option exercises (in shares)		593,173
Issuance of restricted stock awards (in shares)		404,749
Vesting of restricted stock units (in shares)		129,856
Stock-based compensation	6,021		6,021
Other comprehensive loss	(37)				$ (37)
Net loss	(21,761)			(21,761)
Balance at Dec. 31, 2014	70,265	$ 48	202,139	(131,885)	(37)
Balances (in shares) at Dec. 31, 2014		47,614,150
Increase (Decrease) in Stockholders' Equity
Issuance of common stock from option exercises	1,161	$ 1	1,160
Issuance of common stock from option exercises (in shares)		1,126,795
Forfeiture of restricted stock awards, net (in shares)		(136,444)
Vesting of restricted stock units (in shares)		487,759
Stock-based compensation	5,673		5,673
Other comprehensive loss	13				13
Net loss	(21,013)			(21,013)
Balance at Dec. 31, 2015	56,099	$ 49	208,972	(152,898)	(24)
Balances (in shares) at Dec. 31, 2015		49,092,260
Increase (Decrease) in Stockholders' Equity
Issuance of common stock from option exercises	715	$ 1	714
Issuance of common stock from option exercises (in shares)		369,173
Forfeiture of restricted stock awards, net (in shares)		(62,500)
Vesting of restricted stock units (in shares)		114,595
Stock-based compensation	3,627		3,627
Other comprehensive loss	(8)				(8)
Net loss	(15,437)			(15,437)
Balance at Dec. 31, 2016	$ 44,996	$ 50	$ 213,313	$ (168,335)	$ (32)
Balances (in shares) at Dec. 31, 2016		49,513,528