Summary of Significant Accounting Policies - PAC - Schedule of Allowance for Credit Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Charged to operating costs and expenses, net	$ 81	$ 56	$ 47
Write-offs, net	(50)	(28)	(45)
PAC
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	17	8	8
Charged to operating costs and expenses, net	13	18	13
Write-offs, net	(12)	(9)	(13)
Ending balance	$ 18	$ 17	$ 8