Stockholders' Equity - Summary of Reserved Shares of Common Stock for Future Issuance (Details) - shares	Dec. 31, 2017	Dec. 31, 2016	Feb. 28, 2014
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	7,341,253	5,523,127
Warrant To Purchase Common Stock
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	509,611
Stock Options and Restricted Stock Units
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	4,388,752	3,579,694
2014 Plans
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	1,790,600	1,140,328	1,785,000
Employee Stock Purchase Plan
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	652,290	803,105