Derivative Financial Instruments (Net Investment Hedge Gains and Losses Recognized in AOCI) (Details) - Net Investment Hedges - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative [Line Items]
Hedging Instrument Gain/(Loss) Recognized in AOCI (Before Tax)	$ 49.1	$ 119.9	$ 84.6	$ 79.7
Foreign Exchange Contracts
Derivative [Line Items]
Hedging Instrument Gain/(Loss) Recognized in AOCI (Before Tax)	49.1	106.2	79.6	74.3
Sterling Denominated Subordinated Debt
Derivative [Line Items]
Hedging Instrument Gain/(Loss) Recognized in AOCI (Before Tax)	$ 0.0	$ 13.7	$ 5.0	$ 5.4