Net Loss per Share - Anti-Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share (Details) - shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	5,272,647	3,301,354
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	509,611
Outstanding Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	3,857,607	2,706,718
Unvested Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	43,041	189,273
Unvested Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	862,388	405,363