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		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Interest rate swap contract | Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
(Loss)/Gain Recognized on Swap	$ (1.3)	$ (0.3)	$ (3.2)	$ (3.5)
Gain/(Loss) Recognized on Long-Term Debt	$ 1.3	$ 0.3	$ 3.2	$ 3.5