Derivative Financial Instruments (Location and Amount of Fair Value And Cash Flow Hedge Derivative Gains And Losses Recorded In Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income	$ 343.1	$ 406.3	$ 693.0	$ 935.5
Interest Expense	7.5	34.2	17.3	155.3
Other Operating Income	54.4	56.5	109.3	90.9
INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized on fair value hedges	(2.0)	3.1	(3.6)	2.6
Gains (Losses) on cash flow hedges recognized on	2.7	2.6	8.2	6.7
INTEREST EXPENSE
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized on fair value hedges	24.5	11.5	31.5	8.6
Gains (Losses) on cash flow hedges recognized on	0.0	0.0	0.0	0.0
OTHER OPERATING INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized on fair value hedges	0.0	0.0	0.0	0.0
Gains (Losses) on cash flow hedges recognized on	(2.5)	(0.1)	(3.5)	(0.2)
Interest Rate Contracts | INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	(0.5)	(14.7)	17.9	(90.7)
Recognized on hedged items	0.5	14.7	(17.9)	90.7
Amounts related to interest settlements on derivatives	(2.0)	3.1	(3.6)	2.6
Gains (Losses) on cash flow hedges recognized on	0.0	0.1	0.0	0.1
Interest Rate Contracts | INTEREST EXPENSE
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	31.9	4.6	(111.0)	155.0
Recognized on hedged items	(31.9)	(4.6)	111.0	(155.0)
Amounts related to interest settlements on derivatives	24.5	11.5	31.5	8.6
Gains (Losses) on cash flow hedges recognized on	0.0	0.0	0.0	0.0
Interest Rate Contracts | OTHER OPERATING INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	0.0	0.0	0.0	0.0
Recognized on hedged items	0.0	0.0	0.0	0.0
Amounts related to interest settlements on derivatives	0.0	0.0	0.0	0.0
Gains (Losses) on cash flow hedges recognized on	0.0	0.0	0.0	0.0
Foreign Exchange Contracts | INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) on cash flow hedges recognized on	2.7	2.5	8.2	6.6
Foreign Exchange Contracts | INTEREST EXPENSE
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) on cash flow hedges recognized on	0.0	0.0	0.0	0.0
Foreign Exchange Contracts | OTHER OPERATING INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) on cash flow hedges recognized on	$ (2.5)	$ (0.1)	$ (3.5)	$ (0.2)