Preferred Stock, Common Stock and Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Detail) - shares	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock options issued and outstanding	1,275,624	1,037,500
Authorized for future option grants	628,801	78,854
Warrants to purchase common stock	3,323,876	118,881
Authorized for employee stock purchase plan	37,463	41,530
Total common stock reserved for future issuance	5,265,764	1,276,765