Derivative Financial Instruments - Notional Amount of Interest Rate Swap Agreements Outstanding Maturity (Detail) - Interest Rate Swap Agreements [Member]	Dec. 31, 2015 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
2016	$ 500,000,000
2017	400,000,000
2018	500,000,000
Total	$ 1,400,000,000