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Stock Incentive and Employee Benefit Plans - Fair Value of Employee and Director Stock Options (Details) - Employee Stock Option - $ / shares
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted-average grant date fair value $ 7.49 $ 4.54 $ 3.40
Dividend yield 0.00% 0.00% 0.00%
Volatility 110.00% 105.00% 96.00%
Risk-free interest rate 0.96% 0.46% 2.02%
Expected life of options (years) 5 years 8 months 12 days 5 years 8 months 12 days 6 years