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		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income	$ 2,144.3	$ 2,530.2	$ 6,498.0	$ 7,482.3
Interest Expense	1,553.5	1,967.9	4,728.6	5,869.0
INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized on fair value hedges	9.7	29.3	27.9	79.9
Gains (Losses) on cash flow hedges recognized on	0.2	0.6	14.1	7.1
INTEREST EXPENSE
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized on fair value hedges	(15.2)	(20.1)	(44.6)	(59.9)
Gains (Losses) on cash flow hedges recognized on	0.0	0.0	0.0	0.0
Interest Rate Contracts | INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	(2.1)	(251.6)	(149.7)	(94.1)
Recognized on hedged items	2.1	251.6	149.7	94.1
Amounts related to interest settlements on derivatives	9.7	29.3	27.9	79.9
Interest Rate Contracts | INTEREST EXPENSE
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	11.6	76.5	76.3	46.5
Recognized on hedged items	(11.6)	(76.5)	(76.3)	(46.5)
Amounts related to interest settlements on derivatives	(15.2)	(20.1)	(44.6)	(59.9)
Foreign Exchange Contracts | INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) on cash flow hedges recognized on	0.2	0.6	14.1	7.1
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