Stock-based Compensation - Schedule of Assumptions Used to Determine Fair Value of Option Grants (Detail) |
12 Months Ended | |
---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
|
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
Risk-free interest rate, Minimum | 1.18% | 1.47% |
Risk-free interest rate, Maximum | 2.02% | 2.43% |
Expected volatility, Minimum | 79.42% | 84.93% |
Expected volatility, Maximum | 116.88% | 116.81% |
Weighted average expected volatility | 89.12% | 89.26% |
Expected dividend yield | 0.00% | 0.00% |
Minimum [Member] | ||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
Expected lives (in years) | 5 years 2 months 12 days | 5 years 2 months 12 days |
Maximum [Member] | ||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
Expected lives (in years) | 10 years | 10 years |