Derivative Financial Instruments - Gain or Loss Recorded on Our Non-Qualifying Hedges (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Derivative Related Income (Expense)	$ (4)	$ (49)	$ 259	$ (265)
Interest Rate Contracts [Member] | Derivative related income (expense) [Member]
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Derivative Related Income (Expense)	(4)	(48)	260	(260)
Currency contracts [Member] | Derivative related income (expense) [Member]
Derivatives, Fair Value [Line Items]
Amount of Gain (Loss) Recognized in Derivative Related Income (Expense)	$ 0	$ (1)	$ (1)	$ (5)