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Commitments and Contingencies - Additional Information (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Commitments and Contingencies Disclosure [Line Items]    
Rental expense $ 5.4 $ 3.6
General and Administrative Expense    
Commitments and Contingencies Disclosure [Line Items]    
Accrued expenses on settlement of case 1.0  
Rental expense 2.2 1.9
Fulfilment Expense    
Commitments and Contingencies Disclosure [Line Items]    
Rental expense $ 3.2 $ 1.7