Stock-Based Compensation - Summary of Weighted-Average Assumptions Used in the Black-Scholes Option Pricing Model to Determine the Fair Value of the Non-Employee Stock Option Grants (Detail) |
12 Months Ended | |
|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Share-based Goods and Nonemployee Services Transaction [Abstract] | ||
| Risk-free interest rate | 1.79% | 0.89% |
| Expected volatility | 63.20% | 99.40% |
| Expected term (in years) | 6 years 1 month 28 days | 2 years 5 months 19 days |
| Expected dividend yield | 0.00% | 0.00% |