Net Loss per Share - Anti-dilution (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from the calculation of diluted net loss per share attributable to common stockholders	2,921,964	1,792,324	9,184,719
Employee, director and consultant stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from the calculation of diluted net loss per share attributable to common stockholders	2,702,350	1,738,524	500,262
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from the calculation of diluted net loss per share attributable to common stockholders	219,614	53,800
Restricted common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from the calculation of diluted net loss per share attributable to common stockholders			759,538
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from the calculation of diluted net loss per share attributable to common stockholders			7,924,919