Nature of the Business and Basis of Presentation (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 18, 2021
Jul. 20, 2018
Mar. 31, 2021
Mar. 31, 2020
Dec. 31, 2020
Sale of Equity          
Net proceeds after deducting underwriting discounts and commissions     $ 188,000    
Estimated offering cost     800    
Net Loss     (42,330) $ (48,486) $ (167,700)
Accumulated deficit     $ (522,801)   $ (480,471)
Common stock          
Sale of Equity          
Shares issued (in shares)     6,896,552    
Conversion of redeemable convertible preferred stock to common stock (in shares)   51,845,438      
IPO          
Sale of Equity          
Shares issued (in shares)   12,055,450      
Net proceeds after deducting underwriting discounts and commissions   $ 254,300      
Offering          
Sale of Equity          
Shares issued (in shares) 6,896,552        
Net proceeds after deducting underwriting discounts and commissions $ 188,000        
Estimated offering cost $ 800        
Overallotment          
Sale of Equity          
Shares issued (in shares)   1,572,450