Financial Instruments - Summary of Derivative Instruments Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Summary Of Derivative Instruments By Hedge Designation [Abstract]
Net Derivative Asset (Liability)	$ 2	$ (22)
Assets [Member]
Summary Of Derivative Instruments By Hedge Designation [Abstract]
Total Derivative Assets	12	3
Liabilities [Member]
Summary Of Derivative Instruments By Hedge Designation [Abstract]
Total Derivative Liabilities	(10)	(25)
Derivatives Designated as Hedging Instruments [Member]
Summary Of Derivative Instruments By Hedge Designation [Abstract]
Net Derivative Asset (Liability)	(4)	14
Derivatives Designated as Hedging Instruments [Member] | Liabilities [Member]
Summary Of Derivative Instruments By Hedge Designation [Abstract]
Net Derivative Asset (Liability)	0	(13)
Derivatives Designated as Hedging Instruments [Member] | Foreign exchange contracts - forwards [Member] | Other current assets
Summary Of Derivative Instruments By Hedge Designation [Abstract]
Total Derivative Assets	5	1
Derivatives Designated as Hedging Instruments [Member] | Foreign exchange contracts - forwards [Member] | Other current liabilities
Summary Of Derivative Instruments By Hedge Designation [Abstract]
Total Derivative Liabilities	(4)	(15)
Derivatives Designated as Hedging Instruments [Member] | Options Held [Member] | Other current assets
Summary Of Derivative Instruments By Hedge Designation [Abstract]
Total Derivative Assets	3	0
Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swap [Member] | Other long-term assets
Summary Of Derivative Instruments By Hedge Designation [Abstract]
Total Derivative Assets	0	1
Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swap [Member] | Other long-term liabilities
Summary Of Derivative Instruments By Hedge Designation [Abstract]
Total Derivative Liabilities	(4)	0
Not Designated as Hedging Instrument [Member] | Foreign exchange contracts - forwards [Member]
Summary Of Derivative Instruments By Hedge Designation [Abstract]
Net Derivative Asset (Liability)	2	(9)
Not Designated as Hedging Instrument [Member] | Foreign exchange contracts - forwards [Member] | Other current assets
Summary Of Derivative Instruments By Hedge Designation [Abstract]
Total Derivative Assets	4	1
Not Designated as Hedging Instrument [Member] | Foreign exchange contracts - forwards [Member] | Other current liabilities
Summary Of Derivative Instruments By Hedge Designation [Abstract]
Total Derivative Liabilities	$ (2)	$ (10)