Revenues And Accounts Receivable - Allowance for Credit Loss (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($)
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 54
Provisions for credit losses	15
Write-offs	(12)
Ending balance	55
Distribution customers
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	19
Provisions for credit losses	1
Write-offs	(6)
Ending balance	15
Advertising and other customers
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	35
Provisions for credit losses	14
Write-offs	(6)
Ending balance	40
Cumulative Effect, Period Of Adoption, Adjustment
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	(2)
Cumulative Effect, Period Of Adoption, Adjustment | Distribution customers
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1
Cumulative Effect, Period Of Adoption, Adjustment | Advertising and other customers
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ (3)