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, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income	$ 2,189.3	$ 2,212.8	$ 4,423.4	$ 4,353.7
Interest Expense	1,513.8	1,602.3	3,093.9	3,175.1
Income Statement Location [Axis]: us-gaap:InterestAndDividendIncomeOperating
Derivative Instruments, Gain (Loss) [Line Items]
Interest Income	2,189.3	2,212.8	4,423.4	4,353.7
Total gains (losses) recognized on fair value hedges	(4.4)	9.2	(8.1)	18.2
Gains (Losses) on cash flow hedges reclassified from AOCI to net income	8.5	3.4	21.9	13.9
Income Statement Location [Axis]: us-gaap:InterestExpenseOperating
Derivative Instruments, Gain (Loss) [Line Items]
Interest Expense	1,513.8	1,602.3	3,093.9	3,175.1
Total gains (losses) recognized on fair value hedges	(11.8)	(14.8)	(23.4)	(29.4)
Gains (Losses) on cash flow hedges reclassified from AOCI to net income	0.0	0.0	0.0	0.0
Interest Rate Contracts | Income Statement Location [Axis]: us-gaap:InterestAndDividendIncomeOperating
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	46.9	(48.0)	99.7	(147.6)
Recognized on hedged items	(46.9)	48.0	(99.7)	147.6
Amounts related to interest settlements on derivatives	(4.4)	9.2	(8.1)	18.2
Gains (Losses) on cash flow hedges reclassified from AOCI to net income	(2.0)	0.0	(2.4)	0.0
Interest Rate Contracts | Income Statement Location [Axis]: us-gaap:InterestExpenseOperating
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	(23.3)	25.5	(32.9)	64.7
Recognized on hedged items	23.3	(25.5)	32.9	(64.7)
Amounts related to interest settlements on derivatives	(11.8)	(14.8)	(23.4)	(29.4)
Gains (Losses) on cash flow hedges reclassified from AOCI to net income	0.0	0.0	0.0	0.0
Foreign Exchange Contracts | Income Statement Location [Axis]: us-gaap:InterestAndDividendIncomeOperating
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) on cash flow hedges reclassified from AOCI to net income	10.5	3.4	24.3	13.9
Foreign Exchange Contracts | Income Statement Location [Axis]: us-gaap:InterestExpenseOperating
Derivative Instruments, Gain (Loss) [Line Items]
Gains (Losses) on cash flow hedges reclassified from AOCI to net income	$ 0.0	$ 0.0	$ 0.0	$ 0.0