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Stock-based Compensation - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Feb. 06, 2019
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
2019 Equity Incentive Plan        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period 4 years      
Expected weighted average period   2 years 7 months 6 days    
Common stock reserved for issuance   15,628,217    
Percentage of stock owned by Individual 10.00%      
Percentage of exercise price per share from fair market value 110.00%      
Stock options, term 5 years      
Cliff vesting percentage 25.00%      
Cliff vesting period 1 year      
Common stock, shares available for issuance 2,973,219      
Aggregate intrinsic value of option exercised   $ 11.1 $ 1.8 $ 0.0
Unrecognized stock-based compensation   $ 82.9    
Weighted-average grant-date fair value per share of options granted   $ 10.14 $ 12.06 $ 6.27
2019 Employee Stock Purchase Plan        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Purchase price of common stock, percentage 85.00%      
Subsequent offering period 6 months      
Un-recognized compensation expense   $ 0.4    
Minimum | 2019 Equity Incentive Plan        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Stock options, term 10 years      
Restricted Common Stock        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period   4 years    
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   25.00%    
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount   $ 0.9    
Expected weighted average period   9 months 18 days