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Share-based Compensation - Weighted-Average Fair Value Assumptions (Details) - Stock Options
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected dividend yield 0.00% 0.00%
Risk-free interest rate 0.90% 1.80%
Volatility rate 95.00% 81.00%
Expected term (in years) 5 years 9 months 18 days 5 years 9 months 18 days