FAIR VALUE ELECTIONS - Changes in Fair Value Gains (Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Total assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	$ 2,413	$ (2,423)
Securities borrowed and purchased under agreements to resell
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	267	(109)
Trading account assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	97	(296)
Total loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	2,044	(1,764)
Corporate
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	2,038	(1,763)
Consumer loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	6	(1)
Total other assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	5	(254)
MSRs
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	28	201
Certain mortgage loans (HFS)
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	(23)	(455)
Total liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	(13,192)	16,926
Interest-bearing deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	(97)	42
Securities loaned and sold under agreements to repurchase
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	(217)	110
Trading account liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	138	(239)
Short-term borrowings
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	(18)	1,424
Long-term debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	$ (12,998)	$ 15,589