Common Stock - Summary of Reserved Shares of Common Stock for Future Issuances (Detail) - shares	Dec. 31, 2016	Dec. 31, 2015
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	5,998,840	4,845,579
Stock Compensation Plan [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	1,044,113	1,350,543
Options to purchase common stock [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	4,452,700	3,240,969
Restricted stock units [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	502,027	254,067