Accounts Receivable, Net (Allowance for Credit Loss) (Details) $ in Millions	6 Months Ended
	Jun. 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)	225
Write-offs charged against the allowance for expected credit losses	(3)
Other(2)	18
Balance as of June 30, 2020	494
ASU 2016-13 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other(2)	34
COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current period provision for expected credit losses(1)	$ 194