Supplemental Financial Information - Components of Accounts Receivable (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Accounts Receivable, after Allowance for Credit Loss, Current [Abstract]
Accounts Receivable, before Allowance for Credit Loss, Current	$ 1,303	$ 1,534
Accounts Receivable, Allowance for Credit Loss, Current	(55)	(44)
Accounts Receivable, after Allowance for Credit Loss, Current, Total	1,248	1,490
Trade Accounts Receivable [Member]
Accounts Receivable, after Allowance for Credit Loss, Current [Abstract]
Accounts Receivable, before Allowance for Credit Loss, Current	1,260	1,482
Other Receivables [Member]
Accounts Receivable, after Allowance for Credit Loss, Current [Abstract]
Accounts Receivable, before Allowance for Credit Loss, Current	$ 43	$ 52