VARIABLE INTEREST ENTITIES - Schedule of Affordable Housing Tax Credit Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Variable Interest Entity
Income tax expense	$ (95)	$ (96)
Noninterest income	544	517
Net income	373	334
Variable Interest Entity, Not Primary Beneficiary | Net Income (Loss) Attributable To Parent, Net Benefit
Variable Interest Entity
Net income	26	19
Variable Interest Entity, Not Primary Beneficiary | Net benefit (expense) included in income tax expense
Variable Interest Entity
Income tax expense	27	21
Variable Interest Entity, Not Primary Beneficiary | Tax credits recognized
Variable Interest Entity
Income tax expense	106	97
Variable Interest Entity, Not Primary Beneficiary | Other tax benefits recognized
Variable Interest Entity
Income tax expense	23	23
Variable Interest Entity, Not Primary Beneficiary | Amortization
Variable Interest Entity
Income tax expense	(102)	(99)
Variable Interest Entity, Not Primary Beneficiary | Net benefit (expense) included in noninterest income
Variable Interest Entity
Noninterest income	(1)	(2)
Variable Interest Entity, Not Primary Beneficiary | Other income
Variable Interest Entity
Noninterest income	2	1
Variable Interest Entity, Not Primary Beneficiary | Allocated income (loss) on investments
Variable Interest Entity
Noninterest income	$ (3)	$ (3)