Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity Deficit (Unaudited) - 9 months ended Sep. 30, 2015 - USD ($) $ in Thousands	Total	IPO	Private Placement	Convertible Preferred Stock	Convertible Preferred Stock Series E Convertible Preferred Stock	Common Stock	Common Stock IPO	Common Stock Private Placement	Additional Paid-in Capital	Additional Paid-in Capital IPO	Additional Paid-in Capital Private Placement	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance at Dec. 31, 2014	$ (61,297)								$ 346				$ (61,643)
Beginning balance at Dec. 31, 2014	$ 139,963			$ 139,963
Beginning balance, Shares at Dec. 31, 2014	361,997					361,997
Beginning balance, Shares at Dec. 31, 2014	69,608,339			69,608,339
Issuance of stock		$ 124,193	$ 25,000		$ 24,992		$ 1			$ 124,192	$ 25,000
Issuance of stock , Shares					2,361,029		8,050,000	1,470,588
Issuance of convertible preferred stock upon exercise of preferred stock warrants				$ 9
Conversion of convertible preferred stock to common stock	$ 164,964			$ (164,964)		$ 5			164,959
Issuance of preferred stock upon exercise of preferred stock warrants , Shares				6,668
Conversion of convertible preferred stock to common stock, Shares				(71,976,036)		51,822,659
Reclassification of convertible preferred stock and common stock warrant liability to additional paid-in capital	27,066								27,066
Issuance of common stock upon exercise of stock options and grant of restricted stock	$ 300								300
Issuance of common stock upon exercise of stock options and grant of restricted stock, Shares	293,250					298,687
Issuance of common stock upon exercise of warrants	$ 116								116
Issuance of common stock upon exercise of warrants , Shares						258,684
Other comprehensive income	75											$ 75
Stock-based compensation expense	5,109								5,109
Net loss	(42,309)												(42,309)
Ending balance at Sep. 30, 2015	$ 243,217					$ 6			$ 347,088			$ 75	$ (103,952)
Ending balance at Sep. 30, 2015				$ 0
Ending balance, Shares at Sep. 30, 2015	62,290,683					62,290,683
Ending balance, Shares at Sep. 30, 2015	0			0