VARIABLE INTEREST ENTITIES - Schedule of Affordable Housing Tax Credit Investments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Variable Interest Entity
Income tax expense	$ (134)	$ (114)	$ (287)	$ (230)
Noninterest income	506	494	991	992
Net income	478	364	989	784
Variable Interest Entity, Not Primary Beneficiary | Net Income (Loss) Attributable To Parent, Net Benefit
Variable Interest Entity
Net income	21	11	43	23
Variable Interest Entity, Not Primary Beneficiary | Net benefit (expense) included in income tax expense
Variable Interest Entity
Income tax expense	22	11	46	23
Variable Interest Entity, Not Primary Beneficiary | Tax credits recognized
Variable Interest Entity
Income tax expense	87	60	174	121
Variable Interest Entity, Not Primary Beneficiary | Other tax benefits recognized
Variable Interest Entity
Income tax expense	20	16	38	31
Variable Interest Entity, Not Primary Beneficiary | Amortization
Variable Interest Entity
Income tax expense	(85)	(65)	(166)	(129)
Variable Interest Entity, Not Primary Beneficiary | Net benefit (expense) included in noninterest income
Variable Interest Entity
Noninterest income	(1)	0	(3)	0
Variable Interest Entity, Not Primary Beneficiary | Other income
Variable Interest Entity
Noninterest income	2	0	3	0
Variable Interest Entity, Not Primary Beneficiary | Allocated income (loss) on investments
Variable Interest Entity
Noninterest income	$ (3)	$ 0	$ (6)	$ 0