Stockholders' Deficit and Redeemable Convertible Preferred Stock - Preferred Stock Warrants (Details) - $ / shares		12 Months Ended
	Oct. 12, 2016	Dec. 31, 2016	Dec. 31, 2015	Oct. 04, 2016	Oct. 03, 2016	Dec. 31, 2014	Apr. 30, 2014
Preferred stock warrants
Warrants
Warrants issued (in shares)		0	0
Preferred Stock Warrant One | Series A-1 redeemable convertible preferred stock
Warrants
Number of Warrants			250,000
Exercise Price (in dollars per share)			$ 0.800
Term (in years)			10 years
Preferred Stock Warrant Two | Series A-1 redeemable convertible preferred stock
Warrants
Number of Warrants			62,500
Exercise Price (in dollars per share)			$ 0.800
Term (in years)			10 years
Preferred Stock Warrant Three | Series A-1 redeemable convertible preferred stock
Warrants
Exercise Price (in dollars per share)							$ 2.86
Number of shares called by warrant issued							105,005
Preferred Stock Warrant Three | Series B redeemable convertible preferred stock
Warrants
Number of Warrants			105,005
Exercise Price (in dollars per share)			$ 2.860
Term (in years)			10 years
Preferred Stock Warrant Four | Series A-1 redeemable convertible preferred stock
Warrants
Exercise Price (in dollars per share)						$ 2.99
Number of shares called by warrant issued						481,863
Preferred Stock Warrant Four | Series B redeemable convertible preferred stock
Warrants
Number of Warrants			481,863
Exercise Price (in dollars per share)			$ 2.990
Term (in years)			10 years
Common stock warrants
Warrants
Number of Warrants		32,216
Exercise Price (in dollars per share)		$ 1.56
Number of shares called by warrant issued				463,589	232,787
Warrants issued (in shares)		0
Number of warrants exercised (in shares)	431,373