VARIABLE INTEREST ENTITIES - Schedule of Affordable Housing Tax Credit Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Variable Interest Entity
Income tax expense	$ (133)	$ (95)
Noninterest income	606	544
Net income	517	373
Variable Interest Entity, Not Primary Beneficiary | Net Income (Loss) Attributable To Parent, Net Benefit
Variable Interest Entity
Net income	24	26
Variable Interest Entity, Not Primary Beneficiary | Net benefit (expense) included in Income tax expense
Variable Interest Entity
Income tax expense	28	27
Variable Interest Entity, Not Primary Beneficiary | Tax credits recognized
Variable Interest Entity
Income tax expense	110	106
Variable Interest Entity, Not Primary Beneficiary | Other tax benefits recognized
Variable Interest Entity
Income tax expense	25	23
Variable Interest Entity, Not Primary Beneficiary | Amortization
Variable Interest Entity
Income tax expense	(107)	(102)
Variable Interest Entity, Not Primary Beneficiary | Net benefit (expense) included in Noninterest income
Variable Interest Entity
Noninterest income	(4)	(1)
Variable Interest Entity, Not Primary Beneficiary | Other income
Variable Interest Entity
Noninterest income	0	2
Variable Interest Entity, Not Primary Beneficiary | Allocated income (loss) on investments
Variable Interest Entity
Noninterest income	$ (4)	$ (3)