Preferred Stock, Common Stock and Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Detail) - shares	Dec. 31, 2015	Dec. 31, 2014
Common Stock Reserved for Future Issuance [Line Items]
Stock options issued and outstanding	1,037,500	683,500
Authorized for future option grants	78,854	188,370
Warrants to purchase common stock	118,881	118,881
Total common stock reserved for future issuance	1,276,765	1,043,457
Authorized for Employee Stock Purchase Plan [Member]
Common Stock Reserved for Future Issuance [Line Items]
Total common stock reserved for future issuance	41,530	52,706