Condensed Consolidated Statements of Stockholders' Equity - 9 months ended Sep. 30, 2015 - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Accumulated deficit
Balance at Dec. 31, 2014	$ 30,409	$ 41	$ 143,086	$ (112,718)
Balance (shares) at Dec. 31, 2014	40,856,815	40,856,815
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from common stock offering, net	$ 15,872	$ 3	15,869
Proceeds from equity financing, net (shares)		2,974,136
Stock-based compensation expense	1,550		1,550
Exercise of stock options	$ 255		255
Exercise of stock options (shares)	56,250	56,250
Exercise of warrants	$ 82		82
Exercise of warrants (shares)		11,584
Net loss	(16,802)			(16,802)
Balance at Sep. 30, 2015	$ 31,366	$ 44	$ 160,842	$ (129,520)
Balance (shares) at Sep. 30, 2015	43,898,785	43,898,785