Net Investment Hedge Gains and Losses Recognized in AOCI (Detail) (Net Investment Hedges, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Derivative [Line Items]
Hedging Instrument Gain/(Loss) Recognized in AOCI (Before Tax)	$ 116.6	$ (10.6)
Foreign Exchange Contracts
Derivative [Line Items]
Hedging Instrument Gain/(Loss) Recognized in AOCI (Before Tax)	111.6	(9.0)
Sterling Denominated Subordinated Debt
Derivative [Line Items]
Hedging Instrument Gain/(Loss) Recognized in AOCI (Before Tax)	$ 5.0	$ (1.6)