Statement of Stockholders’ Equity - 9 months ended Sep. 30, 2015 - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Total
Balance at Dec. 31, 2014	$ 314	$ 302,969		$ (243,993)	$ 59,290
Balance (in shares) at Dec. 31, 2014	31,434,272
Increase (Decrease) in Stockholders' Equity
Sale of common stock, net of issuance cost of $7.7 million	$ 86	115,118			115,204
Sale of common stock, net of issuance cost of $7.7 million (in shares)	8,625,000
Issuance of common stock upon exercise and vesting of stock awards	$ 4	539			543
Issuance of common stock upon exercise and vesting of stock awards (in shares)	369,743
Issuance of common stock under the employee stock purchase plan	$ 1	246			247
Issuance of common stock under the employee stock purchase plan (in shares)	47,988
Comprehensive loss			$ (6)	(25,349)	(25,355)
Stock-based compensation expense		3,386			3,386
Balance at Sep. 30, 2015	$ 405	$ 422,258	$ (6)	$ (269,342)	$ 153,315
Balance (in shares) at Sep. 30, 2015	40,477,003