Stock-Based Compensation - Summary of Assumptions that Used to Determine Grant-Date Fair Value of Stock Options Granted to Employees and Members of Board (Detail) |
12 Months Ended | |
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Dec. 31, 2020 |
Dec. 31, 2019 |
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Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract] | ||
Expected option life (years) | 6 years | 5 years 7 months 13 days |
Risk-free interest rate | 0.76% | 2.09% |
Expected volatility | 76.02% | 76.83% |