VARIABLE INTEREST ENTITIES - Schedule of Affordable Housing Tax Credit Investments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Variable Interest Entity
Income tax expense	$ (119)	$ (177)	$ (406)	$ (407)
Noninterest income	492	512	1,483	1,504
Net income	430	636	1,419	1,420
Variable Interest Entity, Not Primary Beneficiary | Net Income (Loss) Attributable To Parent, Net Benefit
Variable Interest Entity
Net income	22	13	65	36
Variable Interest Entity, Not Primary Beneficiary | Net benefit (expense) included in income tax expense
Variable Interest Entity
Income tax expense	22	13	68	36
Variable Interest Entity, Not Primary Beneficiary | Tax credits recognized
Variable Interest Entity
Income tax expense	76	59	250	180
Variable Interest Entity, Not Primary Beneficiary | Other tax benefits recognized
Variable Interest Entity
Income tax expense	17	15	55	46
Variable Interest Entity, Not Primary Beneficiary | Amortization
Variable Interest Entity
Income tax expense	(71)	(61)	(237)	(190)
Variable Interest Entity, Not Primary Beneficiary | Net benefit (expense) included in noninterest income
Variable Interest Entity
Noninterest income	0	0	(3)	0
Variable Interest Entity, Not Primary Beneficiary | Other income
Variable Interest Entity
Noninterest income	1	0	4	0
Variable Interest Entity, Not Primary Beneficiary | Allocated income (loss) on investments
Variable Interest Entity
Noninterest income	$ (1)	$ 0	$ (7)	$ 0