FAIR VALUE - Schedule of Fair Value, Assets Measured on Nonrecurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale - loans	$ 1,118	$ 799
Loans - collateral dependent loans	146,194	145,362
Level 1 \| Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale - loans	0	0
Loans - collateral dependent loans	0	0
Level 2 \| Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale - loans	733	781
Loans - collateral dependent loans	1,487	1,580
Level 3 \| Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale - loans	385	18
Loans - collateral dependent loans	144,707	143,782
Fair Value, Nonrecurring \| Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale - loans	25	5
Loans - collateral dependent loans	192	186
Other real estate owned	55	104
Fair Value Measurements	272	295
Fair Value, Nonrecurring \| Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale - loans	(4)	(7)
Loans - collateral dependent loans	(44)	(157)
Other real estate owned	(1)	0
Fair Value Measurements	(49)	(164)
Fair Value, Nonrecurring \| Level 1 \| Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale - loans	0	0
Loans - collateral dependent loans	0	0
Other real estate owned	0	0
Fair Value Measurements	0	0
Fair Value, Nonrecurring \| Level 2 \| Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale - loans	0	0
Loans - collateral dependent loans	0	0
Other real estate owned	0	0
Fair Value Measurements	0	0
Fair Value, Nonrecurring \| Level 3 \| Estimated Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale - loans	25	5
Loans - collateral dependent loans	192	186
Other real estate owned	55	104
Fair Value Measurements	$ 272	$ 295