Financial Instruments - Schedule of Interest Rate Swap Agreements Designated as Cash Flow Hedges (Detail) (Pay-Fixed Interest Rate Swaps [Member], USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Maturity Date, 2014 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	$ 500
Fair Value	(1)
Maturity Date	Dec. 31, 2014
Maturity Date, 2016 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	3,000
Fair Value	(183)
Maturity Date	Dec. 31, 2016
Maturity Date, 2017 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	1,000
Fair Value	$ (33)
Maturity Date	Dec. 31, 2017