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Stock Compensation - Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions (Detail)
3 Months Ended 9 Months Ended
Sep. 30, 2021
Sep. 30, 2021
Sep. 30, 2020
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Line Items]      
Expected term (in years) 6 years 1 month 6 days    
Expected volatility, Minimum 75.40% 75.40% 74.00%
Expected volatility, Maximum 75.80% 76.60% 75.70%
Risk-free rate, Minimum 0.90% 0.60% 0.40%
Risk-free rate, Maximum 1.00% 1.10% 1.70%
Minimum [Member]      
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Line Items]      
Expected term (in years)   5 years 6 months 5 years 6 months
Maximum [Member]      
Schedule Of Share Based Payment Award Stock Options Valuation Assumptions [Line Items]      
Expected term (in years)   6 years 1 month 6 days 6 years 1 month 6 days