Stockholders' Equity - Schedule of Number of Shares of Common Stock Reserved for Future Issuance (Detail) - shares	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2013
Class of Stock [Line Items]
Common stock shares reserved for future issuance	5,750,917	5,137,121
Unvested Restricted Stock [Member]
Class of Stock [Line Items]
Common stock shares reserved for future issuance	1,297,054	969,758
Common Stock Options Outstanding [Member]
Class of Stock [Line Items]
Common stock shares reserved for future issuance	1,267,329	1,684,783
Shares Available for Issuance Under the 2013 Stock Plan [Member]
Class of Stock [Line Items]
Common stock shares reserved for future issuance	2,398,031	1,694,077
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
Shares Available for Issuance Under the 2013 Employee Stock Purchase Plan [Member] | Common Stock Options Outstanding [Member]
Class of Stock [Line Items]
Common stock shares reserved for future issuance			788,503