Common Stock - Summary of Reserved Shares of Common Stock for Future Issuances (Detail) - shares	Dec. 31, 2015	Dec. 31, 2014
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	4,845,579	3,900,281
Stock Compensation Plan [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	1,350,543	991,401
Options to purchase common stock [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	3,240,969	2,723,366
Restricted stock units [Member]
Class Of Stock [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	254,067	185,514