Accounts Receivable, Net (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for doubtful accounts		$ (60)	$ (55)	$ (60)	$ (55)
Accounts receivable, net	[1]			1,060	1,236
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at December 31, 2019		55
Provision for receivables		8
Charge-offs		2
Recoveries and other		(1)
Balance at March 31, 2020		$ 60	$ 55
Credit Concentration Risk | Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Concentration risk (percentage)		5.40%	4.30%
Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Invoiced				861	980
Accrued				259	311
Allowance for doubtful accounts		$ (55)	$ (55)	(60)	(55)
Accounts receivable, net				$ 1,060	$ 1,236
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at December 31, 2019		55
Balance at March 31, 2020		$ 60	$ 55

[1] Allowances at March 31, 2020 determined in accordance with ASU 2016-13 adopted effective January 1, 2020 - refer to Notes 2, 8 and 9 for additional information.