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Stockholders' Equity - Summary of Black-Scholes Option Valuation Assumptions (Details) - Stock Options
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Black-Scholes option valuation assumptions      
Risk-free interest rate, minimum 0.63% 0.30% 1.40%
Risk-free interest rate, maximum 1.47% 1.70% 2.70%
Volatility, minimum 89.00% 67.00% 87.00%
Volatility, maximum 93.00% 99.00% 91.00%
Minimum      
Black-Scholes option valuation assumptions      
Weighted average expected term 5 years 3 years 6 months 3 days 5 years
Maximum      
Black-Scholes option valuation assumptions      
Weighted average expected term 6 years 2 months 1 day 6 years 1 month 20 days 6 years 1 month 17 days