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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative [Line Items]
Hedging Instrument Gain/(Loss) Recognized in AOCI (Before Tax)	$ 4.1	$ 49.1	$ 87.6	$ 84.6
Foreign Exchange Contracts
Derivative [Line Items]
Hedging Instrument Gain/(Loss) Recognized in AOCI (Before Tax)	4.1	49.1	87.6	79.6
Sterling Denominated Subordinated Debt
Derivative [Line Items]
Hedging Instrument Gain/(Loss) Recognized in AOCI (Before Tax)	$ 0.0	$ 0.0	$ 0.0	$ 5.0