Net Loss Per Common Share - Schedule of Potentially Dilutive Securities Excluded from Diluted Net Loss Per Common Share (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities
Potentially dilutive securities excluded from diluted net loss per common share	1,653,958	3,902,602	3,809,605
Redeemable Convertible Preferred Stock
Antidilutive Securities
Potentially dilutive securities excluded from diluted net loss per common share		2,486,199	2,486,199
Options to purchase common stock
Antidilutive Securities
Potentially dilutive securities excluded from diluted net loss per common share	1,414,730	927,175	852,639
Common stock subject to repurchase
Antidilutive Securities
Potentially dilutive securities excluded from diluted net loss per common share	211,538	461,538	461,538
Redeemable Convertible Preferred Stock Warrants
Antidilutive Securities
Potentially dilutive securities excluded from diluted net loss per common share		27,690	9,229
Common Stock Warrants
Antidilutive Securities
Potentially dilutive securities excluded from diluted net loss per common share	27,690