Accounts Receivable, Net - Summary (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended		12 Months Ended
		Sep. 30, 2020		Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2020		Dec. 31, 2019		Sep. 30, 2020		Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for doubtful accounts		$ (63)	[1]	$ (60)	$ (60)	$ (63)	[1]	$ (55)	[1]	$ (63)	[1]	$ (55)	[1]
Accounts receivable, net	[1]									895		1,236
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance		63	[1]	60	60	$ 63	[1]	$ 55	[1]
Provision for receivables		7		9	8
Charge-offs		(6)		(8)	(2)
Recoveries and other		2		$ (1)	$ (1)
Credit Concentration Risk | Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Concentration risk (percentage)						6.60%		4.30%
Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Invoiced										731		980
Accrued										227		311
Allowance for doubtful accounts		(63)				$ (63)		$ (55)		(63)		(55)
Accounts receivable, net										$ 895		$ 1,236
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance		$ 63				$ 63		$ 55

[1] Allowances at September 30, 2020 determined in accordance with ASU 2016-13 adopted effective January 1, 2020 - refer to Notes 2, 8 and 9 for additional information.