Stockholders' Equity - Schedule of Shares of Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	5,711,913	4,925,986
Employee Stock Option
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	4,094,532	3,590,393
Restricted stock units
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	195,172	107,250
Future Stock Grants
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	947,199	724,723
2014 Employee Stock Purchase Plan | Employee Stock
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	475,010	503,620