Location and Amounts of Gains and Losses on Derivative Instrument Designated as Fair Value Hedge (Detail) (Interest rate swap contract, Interest Expense, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Interest rate swap contract | Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Loss Recognized on Swap	$ (1.0)	$ (1.0)
Gain Recognized on Debt	$ 1.0	$ 1.0