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, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income	$ 2,212.8	$ 2,506.5	$ 4,353.7	$ 4,952.1
Interest Expense	1,602.3	1,983.6	3,175.1	3,901.1
Other Operating Income	56.4	924.7	107.1	985.7
INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized on fair value hedges	9.2	28.3	18.2	50.6
Gains (Losses) on cash flow hedges recognized on	3.4	1.0	13.9	6.5
INTEREST EXPENSE
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized on fair value hedges	(14.8)	(19.9)	(29.4)	(39.8)
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	(48.0)	34.5	(147.6)	157.5
Recognized on hedged items	48.0	(34.5)	147.6	(157.5)
Amounts related to interest settlements on derivatives	9.2	28.3	18.2	50.6
Interest Rate Contracts \| INTEREST EXPENSE
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	25.5	0.1	64.7	(30.0)
Recognized on hedged items	(25.5)	(0.1)	(64.7)	30.0
Amounts related to interest settlements on derivatives	(14.8)	(19.9)	(29.4)	(39.8)
Foreign Exchange Contracts \| INTEREST INCOME
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) on cash flow hedges recognized on	3.4	1.0	13.9	6.5
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

Change in Unrealized Gain (Loss) on Amounts Related to Settlement

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Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

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Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period.

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Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein.

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Amount, after tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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