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Accounting for Stock-Based Compensation - Schedule of Share-based Payment Awards, Stock Options, Valuation Assumptions (Details) - Employee Stock Option
3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility   73.50%
Expected volatility, minimum 84.30%  
Expected volatility, maximum 88.90%  
Expected term   6 years
Risk-free interest rate   1.00%
Risk-free interest rate, minimum 0.30%  
Risk-free interest rate, maximum 0.90%  
Minimum    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term 3 years  
Maximum    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term 6 years