Commitments and Contingent Liabilities - Summary of Off-Balance Sheet Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Loss Contingencies [Line Items]
ONE YEAR AND LESS	$ 235,892.4	$ 162,025.4
OVER ONE YEAR	18,829.2	17,732.6
TOTAL	254,721.6	179,758.0
Undrawn Commitments
Loss Contingencies [Line Items]
Commitments, participated to others	222.5	266.6
Securities Lent with Indemnification
Loss Contingencies [Line Items]
ONE YEAR AND LESS	141,392.4	130,311.0
OVER ONE YEAR	0.0	0.0
TOTAL	141,392.4	130,311.0
Secured by Cash Deposits or Participated to Others | Standby Letters of Credit
Loss Contingencies [Line Items]
TOTAL	33.4	35.1
Standby Letter of Credit and Financial Guarantee
Loss Contingencies [Line Items]
Guarantor obligations, current carrying value	61,400.0	16,300.0
Undrawn Commitments
Loss Contingencies [Line Items]
ONE YEAR AND LESS	12,409.2	13,639.2
OVER ONE YEAR	18,452.1	17,321.4
TOTAL	30,861.3	30,960.6
Standby Letters of Credit
Loss Contingencies [Line Items]
ONE YEAR AND LESS	62,939.0	17,553.0
OVER ONE YEAR	375.8	409.9
TOTAL	63,314.8	17,962.9
Commercial Letters of Credit
Loss Contingencies [Line Items]
ONE YEAR AND LESS	24.5	25.4
OVER ONE YEAR	1.3	1.3
TOTAL	25.8	26.7
Reverse repurchase agreements
Loss Contingencies [Line Items]
ONE YEAR AND LESS	19,127.3	496.8
OVER ONE YEAR	0.0	0.0
TOTAL	$ 19,127.3	$ 496.8