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Summary of Significant Accounting Policies - Narrative (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Jun. 30, 2021
Jun. 30, 2020
Accounting Policies [Abstract]        
Amortization of contract costs $ 167.7 $ 162.3 $ 328.6 $ 320.7