Schedule Of Effect Of Derivatives Recognized (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Cost-method Investments [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 11	$ 15
Derivatives not designated as hedging instruments	91	(58)	$ (79)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	8	13
Interest Expense [Member]
Schedule of Cost-method Investments [Line Items]
Derivatives not designated as hedging instruments	23	(68)	(32)
Operating Expense [Member]
Schedule of Cost-method Investments [Line Items]
Derivatives not designated as hedging instruments	19	26	(16)
Designated as Hedging Instrument \| Interest Rate Swap [Member]
Schedule of Cost-method Investments [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	8	7
Interest rate swaps	3	4	(1)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	0	4
Designated as Hedging Instrument \| Foreign Exchange Forward [Member]
Schedule of Cost-method Investments [Line Items]
Interest rate swaps	(50)	14	34
Not Designated as Hedging Instrument \| Foreign Exchange Forward [Member]
Schedule of Cost-method Investments [Line Items]
Derivatives not designated as hedging instruments	42	(42)	(48)
Not Designated as Hedging Instrument \| Currency Swap [Member]
Schedule of Cost-method Investments [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	3	7
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	7	2
Not Designated as Hedging Instrument \| Interest Rate Contract
Schedule of Cost-method Investments [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	0	1
Derivatives not designated as hedging instruments	1	2	2
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	1	7
Not Designated as Hedging Instrument \| Commodity Contract
Schedule of Cost-method Investments [Line Items]
Derivatives not designated as hedging instruments	$ 1	$ 0	$ 0

Fair value, after offset of derivative liability, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226008-175313

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-Publisher FASB
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-Publisher FASB
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

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