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Employee Compensation and Benefit Plans - Schedule of Assumptions used to Value Stock Awards Granted (Details) - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Monte Carlo [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate, minimum (percentage) 0.08% 1.16% 1.15%
Risk-free interest rate, maximum (percentage) 0.29% 2.40% 1.18%
Expected stock price volatility, minimum (percentage) 88.70% 72.50% 71.00%
Expected stock price volatility, maximum (percentage) 94.10% 75.90% 74.00%
Black Scholes [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate (percentage) 2.60%    
Risk-free interest rate, minimum (percentage)   2.79%  
Risk-free interest rate, maximum (percentage)   3.14%  
Expected stock price volatility (percentage) 68.00% 67.00%  
Expected option life (in years)   8 years 6 months 8 years 6 months
Minimum | Monte Carlo [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Fair value (USD per share) $ 24.36 $ 26.25 $ 27.60
Minimum | Black Scholes [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Fair value (USD per share)   20.55 22.95
Maximum | Monte Carlo [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Fair value (USD per share) $ 38.75 33.75 72.00
Maximum | Black Scholes [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Fair value (USD per share)   $ 23.25 $ 44.40