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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Interest rate swap contract | Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
(Loss)/Gain Recognized on Swap	$ (0.9)	$ (2.1)	$ (1.9)	$ (3.2)
Gain/(Loss) Recognized on Long-Term Debt	$ 0.9	$ 2.1	$ 1.9	$ 3.2