Derivative Instruments and Hedging Activities - Derivative Instruments Designated as Fair Value Hedges (Detail) (Interest rate swaps [Member], Interest expense [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Interest rate swaps [Member] | Interest expense [Member]
Derivatives And Hedging Activities [Line Items]
Gain / (Loss) on Instrument	$ (24.6)	$ 6.1	$ 26.3
Gain / (Loss) on Hedged Item	$ 24.6	$ (6.1)	$ (26.3)