Revenue - Accounts Receivable, Unbilled Services, and Deferred Revenue (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($)
Accounts receivable
Accounts receivable, beginning balance	$ 262,012
Additions	1,601,385
Deductions	(1,788,114)
Accounts receivable, ending balance	75,283
Unbilled receivable
Unbilled Receivables, beginning balance	0
Additions	635,975
Deductions	(601,297)
Unbilled receivables, ending balance	34,678
Deferred revenue
Deferred revenue beginning balance	273,228
Additions	1,277,247
Deductions	(288,115)
Deferred revenue, ending balance	$ 1,262,360