GUARANTEES, LEASES AND COMMITMENTS - Credit Commitments and Lines of Credit (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Guarantor Obligations
Credit commitments	$ 1,068,138	$ 1,062,781
Unsettled reverse repurchase and securities borrowing agreements	153,000	126,600
Unsettled repurchase and securities lending agreements	48,600	41,100
Commercial and similar letters of credit
Guarantor Obligations
Credit commitments	6,818	5,910
One- to four-family residential mortgages
Guarantor Obligations
Credit commitments	4,430	4,351
Revolving open-end loans secured by one- to four-family residential properties
Guarantor Obligations
Credit commitments	7,676	7,913
Commercial real estate, construction and land development
Guarantor Obligations
Credit commitments	15,013	17,843
Credit card lines
Guarantor Obligations
Credit commitments	707,087	700,559
Commercial and other consumer loan commitments
Guarantor Obligations
Credit commitments	321,244	320,556
Other commitments and contingencies
Guarantor Obligations
Credit commitments	5,870	$ 5,649
U.S.
Guarantor Obligations
Credit commitments	845,856
U.S. | Commercial and similar letters of credit
Guarantor Obligations
Credit commitments	830
U.S. | One- to four-family residential mortgages
Guarantor Obligations
Credit commitments	1,855
U.S. | Revolving open-end loans secured by one- to four-family residential properties
Guarantor Obligations
Credit commitments	6,564
U.S. | Commercial real estate, construction and land development
Guarantor Obligations
Credit commitments	13,073
U.S. | Credit card lines
Guarantor Obligations
Credit commitments	606,384
U.S. | Commercial and other consumer loan commitments
Guarantor Obligations
Credit commitments	211,495
U.S. | Other commitments and contingencies
Guarantor Obligations
Credit commitments	5,655
Outside of  U.S.
Guarantor Obligations
Credit commitments	222,282
Outside of  U.S. | Commercial and similar letters of credit
Guarantor Obligations
Credit commitments	5,988
Outside of  U.S. | One- to four-family residential mortgages
Guarantor Obligations
Credit commitments	2,575
Outside of  U.S. | Revolving open-end loans secured by one- to four-family residential properties
Guarantor Obligations
Credit commitments	1,112
Outside of  U.S. | Commercial real estate, construction and land development
Guarantor Obligations
Credit commitments	1,940
Outside of  U.S. | Credit card lines
Guarantor Obligations
Credit commitments	100,703
Outside of  U.S. | Commercial and other consumer loan commitments
Guarantor Obligations
Credit commitments	109,749
Outside of  U.S. | Other commitments and contingencies
Guarantor Obligations
Credit commitments	$ 215