FAIR VALUE ELECTIONS - Changes in Fair Value Gains (Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Securities borrowed and purchased under agreements to resell
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	$ (95)	$ (21)	$ (10)	$ (83)
Trading account assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	18	(177)	79	(238)
Certain corporate loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	635	(1,523)	326	(1,855)
Certain consumer loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	(4)	0	1	(1)
Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	631	(1,523)	327	(1,856)
MSRs
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	22	60	19	158
Certain mortgage loans HFS
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	(18)	(144)	(10)	(330)
Total other assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	4	(84)	9	(172)
Total assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	558	(1,805)	405	(2,349)
Interest-bearing deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	82	(168)	(52)	(123)
Securities loaned and sold under agreements to repurchase
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	49	19	(19)	96
Trading account liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	77	191	152	(449)
Short-term borrowings
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	230	1,064	88	1,196
Long-term debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	(2,147)	9,642	(6,496)	15,713
Total liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	$ (1,709)	$ 10,748	$ (6,327)	$ 16,433