Derivative Financial Instruments (Cash Flow Hedge Derivative Gains and Losses Recognized in AOCI and Reclassified to Earnings) (Details) - Asset And Liability Management - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Foreign Exchange Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Net Gain/(Loss) Recognized in AOCI	$ 3.1	$ (0.5)	$ 19.4	$ 1.7
Net Gain/(Loss) Reclassified from AOCI to Net Income
Net Gain/(Loss) Reclassified from AOCI to Net Income	6.0	(5.4)	16.2	(7.6)
Interest Rate Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Net Gain/(Loss) Recognized in AOCI	(0.2)	(5.9)	1.2	1.9
Net Gain/(Loss) Reclassified from AOCI to Net Income
Net Gain/(Loss) Reclassified from AOCI to Net Income	0.1	0.7	0.2	2.5
Net Gain/(Loss) Reclassified from AOCI to Net Income | Foreign Exchange Contracts
Net Gain/(Loss) Reclassified from AOCI to Net Income
Other Operating Income	1.7	(6.8)	4.2	(8.5)
Interest Income	4.2	1.6	12.1	1.6
Other Operating Expense	0.1	(0.2)	(0.1)	(0.7)
Net Gain/(Loss) Reclassified from AOCI to Net Income | Interest Rate Contracts
Net Gain/(Loss) Reclassified from AOCI to Net Income
Other Operating Income	0.0	0.0	0.0	0.0
Interest Income	0.1	0.7	0.2	2.5
Other Operating Expense	$ 0.0	$ 0.0	$ 0.0	$ 0.0