Warrants (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Jan. 31, 2017
Class of Warrant or Right [Line Items]
Exercise price of warrants (in dollars per share)			$ 0.001
Warrants exercised via cashless exercises	0	419,244
Warrants exercised for cash		313,756
Cash proceeds generated from exercise of warrants		$ 2.1
Shares of common stock issued from exercise of warrants		603,545.000
Class of Warrants Issued April 4, 2011
Class of Warrant or Right [Line Items]
Exercise price of warrants (in dollars per share)	$ 0.001
Number of warrants outstanding	7,258,263
November 21, 2012 Warrants
Class of Warrant or Right [Line Items]
Exercise price of warrants (in dollars per share)	$ 7.86
Number of warrants outstanding	695,383