GUARANTEES AND COMMITMENTS - Credit Commitments and Lines of Credit (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Guarantor Obligations
Credit commitments	$ 1,048,847	$ 1,021,802
Unsettled reverse repurchase and securities borrowing agreements	128,600	120,900
Unsettled repurchase and securities lending agreements	135,300	96,400
Commercial and similar letters of credit
Guarantor Obligations
Credit commitments	4,128	5,345
One- to four-family residential mortgages
Guarantor Obligations
Credit commitments	1,091	1,245
Revolving open-end loans secured by one- to four-family residential properties
Guarantor Obligations
Credit commitments	5,303	5,495
Commercial real estate, construction and land development
Guarantor Obligations
Credit commitments	13,087	15,266
Credit card lines
Guarantor Obligations
Credit commitments	682,382	677,005
Commercial and other consumer loan commitments
Guarantor Obligations
Credit commitments	337,744	312,300
Other commitments and contingencies
Guarantor Obligations
Credit commitments	5,112	5,146
U.S.
Guarantor Obligations
Credit commitments	869,691
U.S. | Commercial and similar letters of credit
Guarantor Obligations
Credit commitments	779
U.S. | One- to four-family residential mortgages
Guarantor Obligations
Credit commitments	592
U.S. | Revolving open-end loans secured by one- to four-family residential properties
Guarantor Obligations
Credit commitments	5,287
U.S. | Commercial real estate, construction and land development
Guarantor Obligations
Credit commitments	11,458
U.S. | Credit card lines
Guarantor Obligations
Credit commitments	621,106
U.S. | Commercial and other consumer loan commitments
Guarantor Obligations
Credit commitments	225,558
U.S. | Other commitments and contingencies
Guarantor Obligations
Credit commitments	4,911
U.S. | Other commitments and contingencies | Federal Reserve Bank Stock
Guarantor Obligations
Credit commitments	4,500	$ 4,500
In offices outside North America
Guarantor Obligations
Credit commitments	179,156
In offices outside North America | Commercial and similar letters of credit
Guarantor Obligations
Credit commitments	3,349
In offices outside North America | One- to four-family residential mortgages
Guarantor Obligations
Credit commitments	499
In offices outside North America | Revolving open-end loans secured by one- to four-family residential properties
Guarantor Obligations
Credit commitments	16
In offices outside North America | Commercial real estate, construction and land development
Guarantor Obligations
Credit commitments	1,629
In offices outside North America | Credit card lines
Guarantor Obligations
Credit commitments	61,276
In offices outside North America | Commercial and other consumer loan commitments
Guarantor Obligations
Credit commitments	112,186
In offices outside North America | Other commitments and contingencies
Guarantor Obligations
Credit commitments	$ 201