Financial Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Total foreign currency forward-exchange contracts	$ (25)	$ (10)
Foreign Exchange Forward \| Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Total foreign currency forward-exchange contracts	(2)	1
Gain (loss) on derivative contracts not designated as hedging instruments	0	6
Foreign Exchange Forward \| Derivatives Not Designated as Hedging Instruments \| Other current assets
Derivatives, Fair Value [Line Items]
Foreign currency forward-exchange contracts	(7)	(6)
Foreign Exchange Forward \| Derivatives Not Designated as Hedging Instruments \| Other current liabilities
Derivatives, Fair Value [Line Items]
Foreign currency forward-exchange contracts	(5)	(7)
Forward Starting Interest Rate Swap Contract [Member] \| Derivatives Designated as Hedging Instruments \| Other non-current assets
Derivatives, Fair Value [Line Items]
Total foreign currency forward-exchange contracts	(5)	0
Forward Starting Interest Rate Swap Contract [Member] \| Derivatives Designated as Hedging Instruments \| Other non-current liabilities
Derivatives, Fair Value [Line Items]
Foreign currency forward-exchange contracts	(1)	0
Cross-currency interest rate swap contracts \| Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Unrecognized net gains/(losses) on derivative instruments	12	9
Gains/(losses) on derivative instruments	19	6
Collateral received	12
Cross-currency interest rate swap contracts \| Derivatives Designated as Hedging Instruments \| Other current assets
Derivatives, Fair Value [Line Items]
Total foreign currency forward-exchange contracts	(4)	(3)
Cross-currency interest rate swap contracts \| Derivatives Designated as Hedging Instruments \| Other current liabilities
Derivatives, Fair Value [Line Items]
Total foreign currency forward-exchange contracts	(3)	0
Cross-currency interest rate swap contracts \| Derivatives Designated as Hedging Instruments \| Other non-current assets
Derivatives, Fair Value [Line Items]
Foreign currency forward-exchange contracts	(20)	(8)
Fixed to Floating Interest Rate Swap [Member] \| Derivatives Designated as Hedging Instruments \| Other non-current liabilities
Derivatives, Fair Value [Line Items]
Foreign currency forward-exchange contracts	(2)	0
Forward starting interest rate swap contracts \| Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Foreign currency forward-exchange contracts	23	11
Unrecognized net gains/(losses) on derivative instruments	$ 3	$ 0

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

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Fair value of the assets less the liabilities of a derivative or group of derivatives.

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