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
	Mar. 31, 2025	Mar. 31, 2024
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income	$ 2,140.9	$ 2,445.6
Interest Expense	1,572.8	1,917.5
Other Operating Income	50.7	61.0
INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized on fair value hedges	9.0	22.3
Gains (Losses) on cash flow hedges recognized on	10.5	5.5
INTEREST EXPENSE
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized on fair value hedges	(14.6)	(19.9)
Gains (Losses) on cash flow hedges recognized on	0.0	0.0
Interest Rate Contracts | INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	(99.6)	123.0
Recognized on hedged items	99.6	(123.0)
Amounts related to interest settlements on derivatives	9.0	22.3
Interest Rate Contracts | INTEREST EXPENSE
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	39.2	(30.1)
Recognized on hedged items	(39.2)	30.1
Amounts related to interest settlements on derivatives	(14.6)	(19.9)
Foreign Exchange Contracts | INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) on cash flow hedges recognized on	10.5	5.5
Foreign Exchange Contracts | INTEREST EXPENSE
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) on cash flow hedges recognized on	$ 0.0	$ 0.0