Financial Instruments - Schedule of Interest Rate Swap Agreements Designated as Cash Flow Hedges (Detail) - Jun. 30, 2015 - Pay-Fixed Interest Rate Swaps [Member] - USD ($)	Total
Maturity Date, 2016 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	$ 3,000,000,000
Fair Value	$ (134,000,000)
Maturity Date	Dec. 31, 2016
Maturity Date, 2017 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	$ 1,000,000,000
Fair Value	$ (33,000,000)
Maturity Date	Dec. 31, 2017