Derivative Financial Instruments - Fair Value Hedging Information Including Gain Loss Recorded on Derivative (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Income on Derivative, Total	$ (20)	$ 5	$ 4
Gain (Loss) on Fair Value Hedge Item, Net, Total	17	4	19
Fixed rate borrowings [Member] | Derivative related income (expense) [Member] | Interest rate swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Rate Derivative Fair value Gain (Loss)	(3)	34	17
Interest Rate Fair Value Gain (Loss) on Hedge Item	(2)	(40)	7
Fixed rate borrowings [Member] | Derivative related income (expense) [Member] | Currency swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Foreign Currency Derivative Fair Value Gain (Loss)	(17)	(29)	(13)
Foreign Currency Fair Value Gain (Loss) on Hedge Item	$ 19	$ 44	$ 12