DERIVATIVE FINANCIAL INSTRUMENTS - Gain (Loss) (Details) - Derivatives not designated as Hedging Instruments - Fair Value Hedges - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ 36	$ 38	$ 80	$ 38
Interest rate contracts | Capital markets and advisory fees
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	13	17	34	28
Interest rate contracts | Mortgage banking income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	9	28	9	5
Foreign exchange contracts | Capital markets and advisory fees
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	13	11	37	33
Credit contracts | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	(2)	(6)	(6)	(14)
Commodities contracts | Capital markets and advisory fees
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	0	1	2	3
Equity contracts | Other noninterest income and other noninterest expense
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ 3	$ (13)	$ 4	$ (17)