Stockholders' Equity - Schedule of Number of Shares of Common Stock Reserved for Future Issuance (Detail) - shares	Jun. 30, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Common stock shares reserved for future issuance	6,495,550	5,750,917
Unvested Restricted Stock [Member]
Class of Stock [Line Items]
Common stock shares reserved for future issuance	1,524,058	1,297,054
Common Stock Options Outstanding [Member]
Class of Stock [Line Items]
Common stock shares reserved for future issuance	1,012,833	1,267,329
Shares Available for Issuance Under the 2013 Stock Option and Incentive Plan [Member]
Class of Stock [Line Items]
Common stock shares reserved for future issuance	3,170,156	2,398,031
Shares Available for Issuance Under the 2013 Employee Stock Purchase Plan [Member]
Class of Stock [Line Items]
Common stock shares reserved for future issuance	788,503	788,503