Stockholders' Deficit - Schedule of Common Stock Reserved for Issuance (Details) - shares	Dec. 31, 2016	Dec. 31, 2015
Class Of Stock [Line Items]
Shares reserved for future issuance, shares	3,064,876	3,070,718
Options Issued and Outstanding
Class Of Stock [Line Items]
Shares reserved for future issuance, shares	2,141,868	1,318,647
2015 Stock Option and Incentive Plan
Class Of Stock [Line Items]
Shares reserved for future issuance, shares	720,921	1,497,071
2015 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Shares reserved for future issuance, shares	202,087	255,000