Commitments and Contingent Liabilities (Summary of Off-Balance Sheet Financial Instruments) (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Loss Contingencies [Line Items]
ONE YEAR AND LESS	$ 265,117.5	$ 265,837.5
OVER ONE YEAR	23,015.9	19,549.9
TOTAL	288,133.4	285,387.4
Undrawn Commitments
Loss Contingencies [Line Items]
Commitments, participated to others	288.4	222.2
Securities Lent with Indemnification
Loss Contingencies [Line Items]
ONE YEAR AND LESS	135,526.6	140,539.1
OVER ONE YEAR	0.0	0.0
TOTAL	135,526.6	140,539.1
Secured by Cash Deposits or Participated to Others | Standby Letters of Credit
Loss Contingencies [Line Items]
TOTAL	99.1	39.1
Standby Letter of Credit and Financial Guarantee
Loss Contingencies [Line Items]
Guarantor obligations, current carrying value	100,100.0	84,600.0
Undrawn Commitments
Loss Contingencies [Line Items]
ONE YEAR AND LESS	7,481.8	11,849.5
OVER ONE YEAR	22,691.9	18,909.6
TOTAL	30,173.7	30,759.1
Standby Letters of Credit
Loss Contingencies [Line Items]
ONE YEAR AND LESS	101,508.9	85,752.0
OVER ONE YEAR	323.9	639.0
TOTAL	101,832.8	86,391.0
Commercial Letters of Credit
Loss Contingencies [Line Items]
ONE YEAR AND LESS	29.3	29.2
OVER ONE YEAR	0.1	1.3
TOTAL	29.4	30.5
Reverse repurchase agreements
Loss Contingencies [Line Items]
ONE YEAR AND LESS	20,570.9	27,667.7
OVER ONE YEAR	0.0	0.0
TOTAL	$ 20,570.9	$ 27,667.7