FAIR VALUE ELECTIONS - Changes in Fair Value Gains (Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Total assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	$ 1,229	$ 2,413
Securities borrowed and purchased under agreements to resell
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	77	267
Trading account assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	(28)	97
Total loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	1,127	2,044
Corporate
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	1,137	2,038
Consumer loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	(10)	6
Total other assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	53	5
MSRs
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	37	28
Certain mortgage loans (HFS)
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	16	(23)
Total liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	(6,991)	(13,192)
Deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	(38)	(97)
Securities loaned and sold under agreements to repurchase
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	46	(217)
Trading account liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	(190)	138
Short-term borrowings
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	(524)	(18)
Long-term debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gains (losses) from changes in fair value	$ (6,285)	$ (12,998)