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Stock-Based Compensation - Assumptions Used to Estimate Fair Value of Stock Options (Details)
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate, minimum 0.47% 0.31% 1.42%
Risk-free interest rate, maximum 1.18% 1.70% 2.57%
Volatility, minimum 64.40% 69.80% 70.60%
Volatility, maximum 80.80% 82.70% 99.20%
Dividend yield 0.00% 0.00% 0.00%
Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected life (years) 3 years 6 months 5 years 3 months 18 days 5 years 2 months 12 days
Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected life (years) 6 years 1 month 6 days 6 years 3 months 18 days 6 years 2 months 12 days