FAIR VALUE ELECTIONS - Changes in Fair Value Gains (Losses) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Securities borrowed and purchased under agreements to resell
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	$ (82)	$ (28)	$ (165)	$ (64)
Trading account assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	(69)	(2)	(307)	151
Certain corporate loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	(372)	(292)	(2,227)	376
Certain consumer loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	0	0	(1)	0
Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	(372)	(292)	(2,228)	376
MSRs
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	37	(3)	195	49
Certain mortgage loans HFS
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	(110)	25	(440)	69
Total other assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	(73)	22	(245)	118
Total assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	(596)	(300)	(2,945)	581
Interest-bearing deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	133	54	10	(39)
Securities loaned and sold under agreements to repurchase
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	63	19	159	37
Trading account liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	208	5	(241)	15
Short-term borrowings
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	61	140	1,257	332
Long-term debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	4,922	975	20,635	542
Total liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions.
Gain (loss) from changes in fair value	$ 5,387	$ 1,193	$ 21,820	$ 887