Accounts Receivable, Net (Allowance for Credit Loss) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance as of December 31, 2019	$ 254
Current period provision for expected credit losses(1)	263
Write-offs charged against the allowance for expected credit losses	(5)
Other, net(2)	18
Balance as of September 30, 2020	530
ASU 2016-13 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other, net(2)	34
COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses(1)	$ 223