Schedule Of Effect Of Derivatives Recognized (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Cost-method Investments [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ 6	$ 7
Derivatives not designated as hedging instruments	0	33	(30)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	16	19
Interest Expense [Member]
Schedule of Cost-method Investments [Line Items]
Derivatives not designated as hedging instruments	10	20	32
Operating Expense [Member]
Schedule of Cost-method Investments [Line Items]
Derivatives not designated as hedging instruments	2		1
Derivative Instruments Gain Loss Recognized In Operations		7
Vehicle Interest [Member]
Schedule of Cost-method Investments [Line Items]
Derivatives not designated as hedging instruments		1
Interest Rate Contract \| Interest Expense [Member]
Schedule of Cost-method Investments [Line Items]
Derivatives not designated as hedging instruments		5
Designated as Hedging Instrument \| Interest Rate Swap [Member]
Schedule of Cost-method Investments [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	1	2
Interest rate swaps	(2)	1	13
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	3	1
Not Designated as Hedging Instrument \| Interest Rate Swap [Member]
Schedule of Cost-method Investments [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	0	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	0	0
Not Designated as Hedging Instrument \| Foreign Exchange Forward [Member]
Schedule of Cost-method Investments [Line Items]
Derivatives not designated as hedging instruments	8	27	(31)
Not Designated as Hedging Instrument \| Currency Swap [Member]
Schedule of Cost-method Investments [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	5	3
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	2	5
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	2
Derivatives not designated as hedging instruments	(3)	4	(15)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	10	13
Not Designated as Hedging Instrument \| Commodity Contract
Schedule of Cost-method Investments [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	0	0
Derivatives not designated as hedging instruments	(3)	1	3
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	$ 1	$ 0

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (c)

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-Name Accounting Standards Codification

-Topic 210

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-Section 55

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-Name Accounting Standards Codification

-Topic 815

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Fair value, after offset of derivative asset, of financial liability or 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, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

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