CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - TEMPORARY EQUITY - USD ($) shares in Thousands, $ in Thousands	Convertible Preferred Stock Series C convertible preferred stock	Convertible Preferred Stock Series D convertible preferred stock	Convertible Preferred Stock	Series C convertible preferred stock	Series D convertible preferred stock	Total
Balance at Dec. 31, 2013			$ 156,210
Balance (in shares) at Dec. 31, 2013			21,508
Convertible Preferred Stock
Issuance of convertible preferred stock in connection with exercises of preferred stock warrants	$ 836	$ 333
Issuance of convertible preferred stock in connection with exercises of preferred stock warrants (in shares)	105	29
Balance at Dec. 31, 2014			$ 157,379	$ 40,836	$ 41,496	$ 157,379
Balance (in shares) at Dec. 31, 2014			21,642	5,819	5,410
Convertible Preferred Stock
Issuance of convertible preferred stock in connection with exercises of preferred stock warrants		$ 1,698
Issuance of convertible preferred stock in connection with exercises of preferred stock warrants (in shares)		94
Conversion of preferred stock into common stock			$ (159,077)
Conversion of preferred stock into common stock (in shares)			(21,736)
Balance at Dec. 31, 2015
Balance (in shares) at Dec. 31, 2015