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Stock-Based Compensation - Summary of Restricted Common Stock Activity (Details) - Restricted Common Stock - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Number of Shares    
Number of Shares, Unvested at January 1, 2020 4,403,148  
Number of Shares, Granted 315,023 2,434,515
Number of Shares, Forfeited (22,316)  
Number of Shares, Vested (1,284,876)  
Number of Shares, Unvested at December 31, 2020 3,410,979 4,403,148
Weighted Average Grant Date Fair Value    
Weighted Average Grant Date Fair Value, Unvested at January 1, 2020 $ 1.87  
Weighted Average Grant Date Fair Value, Granted 21.07 $ 2.93
Weighted Average Grant Date Fair Value, Forfeited 19.25  
Weighted Average Grant Date Fair Value, Vested 1.84 1.80
Weighted Average Grant Date Fair Value, Unvested at December 31, 2020 $ 3.55 $ 1.87