FAIR VALUE - Schedule of Fair Value, Assets Measured on Nonrecurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 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	$ 131	$ 799
Loans - collateral dependent loans	153,283	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	48	781
Loans - collateral dependent loans	1,560	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	83	18
Loans - collateral dependent loans	151,723	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	226	186
Other real estate owned	19	104
Fair Value Measurements	270	295
Fair Value, Nonrecurring \| Changes Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets held for sale - loans	(3)	(7)
Loans - collateral dependent loans	(82)	(157)
Other real estate owned	0	0
Fair Value Measurements	(85)	(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	226	186
Other real estate owned	19	104
Fair Value Measurements	$ 270	$ 295