Summary of Significant Accounting Policies - MEC - 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)
MEC
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	12	5	7
Charged to operating costs and expenses, net	10	12	9
Write-offs, net	(10)	(5)	(11)
Ending balance	$ 12	$ 12	$ 5