Derivative Financial Instruments - Gains and Losses on Derivative Instruments Designated and Qualifying As Hedging Instruments in Cash Flow Hedges (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in AOCI on Derivative (Effective Portion)	$ (10)	$ 34	$ (70)	$ 153
Gain (Loss) Recognized in AOCI on Derivative (Effective Portion)	(2)	(2)	(4)	(9)
Gain (Loss) Recognized in Income on the Derivative (Ineffective Portion)	0	0	0	0
Foreign exchange contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in AOCI on Derivative (Effective Portion)	1	2	2	3
Foreign exchange contracts [Member] | Interest Income (Expense), Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in AOCI on Derivative (Effective Portion)	0	0	0	0
Foreign exchange contracts [Member] | Other Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on the Derivative (Ineffective Portion)	0	0	0	0
Interest rate contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in AOCI on Derivative (Effective Portion)	(11)	32	(72)	150
Interest rate contracts [Member] | Interest Income (Expense), Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in AOCI on Derivative (Effective Portion)	(2)	(2)	(4)	(9)
Interest rate contracts [Member] | Other Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on the Derivative (Ineffective Portion)	$ 0	$ 0	$ 0	$ 0