Debt - Assumptions Used in Estimation of Initial Fair Value of Warrants (Detail) - Square 1 Bank [Member] |
12 Months Ended |
|---|---|
Dec. 31, 2015 | |
| Debt Instrument [Line Items] | |
| Risk free interest rate | 2.17% |
| Expected warrant term | 10 years |
| Expected volatility of common stock | 77.19% |
| Expected dividend yield | 0.00% |