VARIABLE INTEREST ENTITIES - Schedule of Variable Interest Entities (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Variable Interest Entity [Line Items]
Total affordable housing tax credit and other unconsolidated investments (maximum loss exposure)	$ 228,822	$ 223,720
Liabilities	206,527	201,492
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Total affordable housing tax credit and other unconsolidated investments (maximum loss exposure)	2,578	2,516
Variable Interest Entity, Not Primary Beneficiary | Total tax credit equity investments
Variable Interest Entity [Line Items]
Total affordable housing tax credit and other unconsolidated investments (maximum loss exposure)	2,408	2,359
Variable Interest Entity, Not Primary Beneficiary | Affordable housing tax credit investments
Variable Interest Entity [Line Items]
Total affordable housing tax credit and other unconsolidated investments (maximum loss exposure)	2,406	2,357
Variable Interest Entity, Not Primary Beneficiary | Other tax credit equity investments
Variable Interest Entity [Line Items]
Total affordable housing tax credit and other unconsolidated investments (maximum loss exposure)	2	2
Variable Interest Entity, Not Primary Beneficiary | Other unconsolidated investments
Variable Interest Entity [Line Items]
Total affordable housing tax credit and other unconsolidated investments (maximum loss exposure)	170	157
Variable Interest Entity, Not Primary Beneficiary | Commitments to tax credit investments
Variable Interest Entity [Line Items]
Liabilities	$ 1,234	$ 1,214