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	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Loss Recognized on Swap	$ (1.2)	$ (1.3)	$ (3.3)	$ (3.2)
Gain Recognized on Long-Term Debt	$ 1.2	$ 1.3	$ 3.3	$ 3.2