Accounts Receivable, Net (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net	$ 1,188	$ 1,276
Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Invoiced	939	999
Accrued	305	333
Allowance for doubtful accounts	(56)	(56)
Accounts receivable, net	$ 1,188	$ 1,276