VARIABLE INTEREST ENTITIES - Schedule of Variable Interest Entities (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Variable Interest Entity [Line Items]
Total affordable housing tax credit and other unconsolidated investments (maximum loss exposure)	$ 236,842	$ 229,698
Liabilities for commitments to fund tax credit investments	214,942	207,460
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Total affordable housing tax credit and other unconsolidated investments (maximum loss exposure)	2,749	2,955
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)	2,513	2,761
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)	2,485	2,761
Variable Interest Entity, Not Primary Beneficiary \| Other tax credit investments
Variable Interest Entity [Line Items]
Total affordable housing tax credit and other unconsolidated investments (maximum loss exposure)	28	0
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)	218	194
Variable Interest Entity, Not Primary Beneficiary \| Tax credit and other unconsolidated VIE investments
Variable Interest Entity [Line Items]
Total affordable housing tax credit and other unconsolidated investments (maximum loss exposure)	2,731	2,955
Variable Interest Entity, Not Primary Beneficiary \| Investment Securities Available For Sale
Variable Interest Entity [Line Items]
Total affordable housing tax credit and other unconsolidated investments (maximum loss exposure)	18	0
Variable Interest Entity, Not Primary Beneficiary \| Commitments to tax credit investments
Variable Interest Entity [Line Items]
Liabilities for commitments to fund tax credit investments	$ 1,166	$ 1,321