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Fair value of all derivative assets designated as fair value hedging instruments.

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Derivative Financial Instruments - Location of Derivative Fair Values in Consolidated Balance Sheet (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Derivative related assets at fair value		$ 64
Interest Rate Liability Derivatives Fair Value	(8)	7
Derivative Related Liabilities [Member] \| Interest rate swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative related liabilities at fair value	(8)	7
Derivative Related Liabilities [Member] \| Currency swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Foreign Currency Liability Derivatives Fair Value
Derivative financial assets [Member] \| Interest rate swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Rate Asset Derivatives Fair Value		11
Derivative financial assets [Member] \| Currency swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Foreign Currency Asset Derivatives Fair Value		$ 53