Warrants (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Class of Warrant or Right [Line Items]
Warrants exercised via cashless exercises	179,296	419,244	192,570
Warrants exercised for cash		313,756
Cash proceeds generated from exercise of warrants		$ 2.1
Shares of common stock issued from exercise of warrants	139,503	603,545.000	148,818.000
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