Supplemental Financial Information - Components of Accounts Receivable (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Accounts Receivable, after Allowance for Credit Loss, Current [Abstract]
Accounts receivable, gross	$ 1,403	$ 1,534
Less: allowance for credit losses	(50)	(44)
Total accounts receivable, net	1,353	1,490
Trade
Accounts Receivable, after Allowance for Credit Loss, Current [Abstract]
Accounts receivable, gross	1,359	1,482
Other
Accounts Receivable, after Allowance for Credit Loss, Current [Abstract]
Accounts receivable, gross	$ 44	$ 52