Financial Instruments (Fair Values Of Derivatives Instruments) (Detail) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Fair Value, Asset Derivatives	$ 26	$ 17
Fair Value, Liability Derivatives	19	22
Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Fair Value, Asset Derivatives	7	12
Fair Value, Liability Derivatives	15	8
Not Designated As Hedging Instruments [Member] | Foreign Exchange Contract [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Fair Value, Asset Derivatives	16	5
Fair Value, Liability Derivatives	4	11
Not Designated As Hedging Instruments [Member] | Interest Rate Contracts [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Fair Value, Asset Derivatives	0	0
Fair Value, Liability Derivatives	0	2
Not Designated As Hedging Instruments [Member] | Commodity Contracts [Member]
Schedule of Cost-method Investments [Line Items] (Deprecated 2018-01-31)
Fair Value, Asset Derivatives	3	0
Fair Value, Liability Derivatives	$ 0	$ 1