VARIABLE INTEREST ENTITIES - Schedule of Affordable Housing Tax Credit Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Variable Interest Entity
Income tax expense	$ (153)	$ (116)
Noninterest income	485	498
Net income	511	420
Variable Interest Entity, Not Primary Beneficiary | Net Income (Loss) Attributable To Parent, Net Benefit
Variable Interest Entity
Net income	22	12
Variable Interest Entity, Not Primary Beneficiary | Net benefit included in income tax expense
Variable Interest Entity
Income tax expense	24	12
Variable Interest Entity, Not Primary Beneficiary | Tax credits recognized
Variable Interest Entity
Income tax expense	87	61
Variable Interest Entity, Not Primary Beneficiary | Other tax benefits recognized
Variable Interest Entity
Income tax expense	18	15
Variable Interest Entity, Not Primary Beneficiary | Amortization
Variable Interest Entity
Income tax expense	(81)	(64)
Variable Interest Entity, Not Primary Beneficiary | Net benefit included in noninterest income
Variable Interest Entity
Noninterest income	(2)	0
Variable Interest Entity, Not Primary Beneficiary | Other income
Variable Interest Entity
Noninterest income	1	0
Variable Interest Entity, Not Primary Beneficiary | Allocated income (loss) on investments
Variable Interest Entity
Noninterest income	$ (3)	$ 0