Significant Accounting Policies - Property and Equipment (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Property and equipment      
Depreciation expenses $ 32.8 $ 26.5 $ 22.4
Computers and equipment | Minimum      
Property and equipment      
Estimated useful lives of assets 3 years    
Computers and equipment | Maximum      
Property and equipment      
Estimated useful lives of assets 4 years    
Furniture and fixtures      
Property and equipment      
Estimated useful lives of assets 5 years