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Stockholders' Equity - Estimates Utilized (Details) - Stock Option - $ / shares
3 Months Ended
Mar. 31, 2022
Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Fair value of options issued (in dollars per share) $ 1.17 $ 4.26
Exercise price (USD per share) $ 1.48 $ 5.51
Expected life of options (in years) 6 years 1 month 6 days 6 years 2 months 12 days
Risk-free interest rate 1.90% 0.80%
Expected volatility 99.20% 96.30%
Dividend yield 0.00% 0.00%