Net Investment Hedge Gains and Losses Recognized in Aoci (Detail) (Net Investment Hedges, USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivative [Line Items]
Hedging Instrument Gain/(Loss) Recognized in AOCI (Before Tax)	$ (3.3)	$ 72.6	$ 79.5	$ 27.4
Foreign Exchange Contracts
Derivative [Line Items]
Hedging Instrument Gain/(Loss) Recognized in AOCI (Before Tax)	(2.0)	63.7	64.3	27.4
Sterling Denominated Subordinated Debt
Derivative [Line Items]
Hedging Instrument Gain/(Loss) Recognized in AOCI (Before Tax)	$ (1.3)	$ 8.9	$ 15.2