VARIABLE INTEREST ENTITIES - Schedule of Affordable Housing Tax Credit Investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
Income tax expense	$ (422)	$ (582)	$ (658)
Noninterest income	1,983	2,009	2,135
Net income	1,608	2,073	2,319
Variable Interest Entity, Not Primary Beneficiary | Net Income (Loss) Attributable To Parent, Net Benefit
Variable Interest Entity [Line Items]
Net income	80	48	42
Variable Interest Entity, Not Primary Beneficiary | Net benefit (expense) included in income tax expense
Variable Interest Entity [Line Items]
Income tax expense	85	48	42
Variable Interest Entity, Not Primary Beneficiary | Tax credits recognized
Variable Interest Entity [Line Items]
Income tax expense	334	236	202
Variable Interest Entity, Not Primary Beneficiary | Other tax benefits recognized
Variable Interest Entity [Line Items]
Income tax expense	71	59	48
Variable Interest Entity, Not Primary Beneficiary | Amortization
Variable Interest Entity [Line Items]
Income tax expense	(320)	(247)	(208)
Variable Interest Entity, Not Primary Beneficiary | Net benefit (expense) included in noninterest income
Variable Interest Entity [Line Items]
Noninterest income	(5)	0	0
Variable Interest Entity, Not Primary Beneficiary | Other income
Variable Interest Entity [Line Items]
Noninterest income	5	0	0
Variable Interest Entity, Not Primary Beneficiary | Allocated income (loss) on investments
Variable Interest Entity [Line Items]
Noninterest income	$ (10)	$ 0	$ 0