Warrants (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2016	Jun. 30, 2014	Jul. 31, 2013
Warrant
Warrants
Exercise price (in dollars per share)		$ 7.25
Warrants exercised	29,330
Number of shares of common stock to be purchased against outstanding warrants		256,590
Series A preferred stock warrant
Warrants
Warrants exercisable into stock (in shares)				1,940,000
Exercise price (in dollars per share)				$ 1.00
Number of shares of common stock to be purchased against outstanding warrants		248,360
Common stock
Warrants
Exercise price (in dollars per share)			$ 15.19
Common stock | Warrant
Warrants
Warrants exercisable into stock (in shares)	25,445		8,230	277,690
Fair value of warrants			$ 0.1
Share price of common stock (in dollars per share)				$ 6.99