Derivative Financial Instruments (Notional Amount and Fair Values of Derivative Financial Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	$ 21,589.5	$ 21,212.0
Asset Fair Value	546.5	190.7
Liability Fair Value	(95.1)	(32.0)
Less: Gross amounts offset in the Consolidated Balance Sheets, Asset Fair Value	0.0	0.0
Less: Gross amounts offset in the Consolidated Balance Sheets, Liability Fair Value	0.0	0.0
Less: Amounts subject to master netting agreements, Asset Fair Value	(17.2)	(11.8)
Less: Amounts subject to master netting agreements, Liability Fair Value	17.2	11.8
Cash collateral pledged (received) subject to master netting agreements, Asset Fair Value	(2.2)	(1.2)
Cash collateral pledged (received) subject to master netting agreements Liability Fair Value	47.5	14.3
Total net derivative fair values, Asset Fair Value	527.1	177.7
Total net derivative fair values, Liability Fair Value	(30.4)	(5.9)
Net amount presented in the Consolidated Balance Sheets, Derivative assets	546.5	190.7
Net amount presented in the Consolidated Balance Sheets, Derivative liabilities	(95.1)	(32.0)
Derivatives designated as hedging instruments (Qualifying Hedges)
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	539.6	1,926.3
Asset Fair Value	0.7	0.0
Liability Fair Value	0.0	(10.6)
Derivatives designated as hedging instruments (Qualifying Hedges) \| Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	39.6	676.3
Asset Fair Value	0.7	0.0
Liability Fair Value	0.0	(10.6)
Derivatives designated as hedging instruments (Qualifying Hedges) \| Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	500.0	1,250.0
Asset Fair Value	0.0	0.0
Liability Fair Value	0.0	0.0
Derivatives not designated as hedging instruments (Non-qualifying Hedges)
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	21,049.9	19,285.7
Asset Fair Value	545.8	190.7
Liability Fair Value	(95.1)	(21.4)
Derivatives not designated as hedging instruments (Non-qualifying Hedges) \| Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	524.4	982.9
Asset Fair Value	20.2	13.7
Liability Fair Value	(12.4)	(6.1)
Derivatives not designated as hedging instruments (Non-qualifying Hedges) \| Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	19,740.1	17,588.1
Asset Fair Value	524.8	176.9
Liability Fair Value	(80.1)	(14.5)
Derivatives not designated as hedging instruments (Non-qualifying Hedges) \| Other contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	785.4	714.7
Asset Fair Value	0.8	0.1
Liability Fair Value	$ (2.6)	$ (0.8)

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Nominal or face amount used to calculate payment on derivative.

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