Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Stockholders' Equity (Deficit)	Common stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive loss	Total
Balance at Dec. 31, 2012	$ 85,517	$ 44	$ 186,778	$ (101,305)
Balances (in shares) at Dec. 31, 2012		44,046,970
Increase (Decrease) in Stockholders' Equity
Issuance of common stock from option exercises	2,671	$ 2	2,669
Issuance of common stock from option exercises (in shares)		2,032,571				2,031,903
Issuance of restricted stock awards, net (in shares)		353,555
Vesting of restricted stock units (in shares)		53,276
Stock-based compensation	5,483		5,483
Net loss	(8,819)			(8,819)		$ (8,819)
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				593,173
Issuance of restricted stock awards, net (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)	$ (37)
Net loss	(21,761)			(21,761)		(21,761)
Balance at Dec. 31, 2014	70,265	$ 48	202,139	(131,885)	(37)	$ 70,265
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				1,126,788
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	$ 13
Net loss	(21,013)			(21,013)		(21,013)
Balance at Dec. 31, 2015	$ 56,099	$ 49	$ 208,972	$ (152,898)	$ (24)	$ 56,099
Balances (in shares) at Dec. 31, 2015		49,092,260