Derivative Instruments and Hedging Activities - Derivative Instruments Designated as Fair Value Hedges (Detail) - Interest Rate Swaps [Member] - Interest Expense [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) on Instrument	$ 10.8	$ (4.9)	$ 10.0	$ 7.0
Gain (Loss) on Hedged Item	$ (10.8)	$ 4.9	$ (10.0)	$ (7.0)