Accounts Receivable, Net (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, net		$ 1,297		$ 1,297		$ 1,357
Accounts Receivable Sales Arrangements [Abstract]
Uncollected accounts receivable sold and derecognized		131		131		161
Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Invoiced		1,001		1,001		1,048
Accrued		353		353		368
Allowance for doubtful accounts		(57)		(57)		$ (59)
Accounts receivable sales(1)	[1]	128	$ 567	231	$ 1,078
Deferred proceeds		0	56	0	108
Loss on sales of accounts receivable		0	3	1	6
Estimated increase (decrease) to operating cash flows(2)	[2]	$ 26	$ 54	$ (25)	$ (11)

[1] Customers may also enter into structured-payable arrangements that require us to sell our receivables from that customer to a third-party financial institution, which then makes payments to us to settle the customer's receivable. In these instances, we ensure the sale of the receivables are bankruptcy remote and the payment made to us is without recourse. The activity associated with these arrangements is not reflected in this disclosure as payments under these arrangements have not been material and these are customer directed arrangements.

[2] Represents the difference between current and prior period receivable sales adjusted for the effects of: (i) the deferred proceeds, (ii) collections prior to the end of the quarter and, (iii) currency.