Preferred Stock, Common Stock and Stockholders' Equity - Summary of Estimated Fair Value of Stock Option Award (Detail) - Stock Options [Member] |
12 Months Ended | |
|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Stock-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Expected dividend yield | 0.00% | 0.00% |
| Minimum [Member] | ||
| Stock-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Risk free interest rate | 1.50% | 1.66% |
| Expected option term | 5 years 6 months | 5 years 6 months |
| Expected volatility of common stock | 71.99% | 71.06% |
| Maximum [Member] | ||
| Stock-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Risk free interest rate | 1.87% | 1.77% |
| Expected option term | 6 years | 6 years |
| Expected volatility of common stock | 76.74% | 73.21% |