DERIVATIVES - Schedule of Derivatives Designated as Accounting Hedge (Details) - Designated as hedging instrument - USD ($) $ in Millions	9 Months Ended	12 Months Ended
Sep. 30, 2026	Dec. 31, 2025
Derivative [Line Items]
Notional Amount	$ 27,805	$ 18,668
Asset, total	82	80
Liability, total	$ 296	$ 27
Weighted Average Receive Rate	3.54%	3.06%
Weighted Average Pay Rate	1.38%	1.41%
Weighted Average
Derivative [Line Items]
Weighted Average Life (Years)	1 year 9 months 18 days	1 year 6 months 7 days
Fair value hedges \| Interest rate swaps - AFS
Derivative [Line Items]
Notional Amount	$ 6,250	$ 3,750
Asset	81	17
Liability	$ 99	$ 4
Weighted Average Receive Rate	2.83%	1.60%
Weighted Average Pay Rate	1.94%	3.01%
Fair value hedges \| Interest rate swaps - AFS \| Weighted Average
Derivative [Line Items]
Weighted Average Life (Years)	3 years 4 months 24 days	2 years 4 months 9 days
Cash flow hedges \| Pay fixed - receive variable interest rate swaps
Derivative [Line Items]
Notional Amount	$ 55	$ 618
Asset	0	0
Liability	$ 0	$ 0
Weighted Average Receive Rate	3.47%	3.87%
Weighted Average Pay Rate	3.86%	3.49%
Cash flow hedges \| Pay fixed - receive variable interest rate swaps \| Weighted Average
Derivative [Line Items]
Weighted Average Life (Years)	3 years 9 months 7 days	3 years 3 months 18 days
Cash flow hedges \| Pay variable - receive fixed interest rate swaps
Derivative [Line Items]
Notional Amount	$ 21,500	$ 14,300
Asset	1	63
Liability	$ 197	$ 23
Weighted Average Receive Rate	3.75%	3.41%
Weighted Average Pay Rate	1.22%	0.90%
Cash flow hedges \| Pay variable - receive fixed interest rate swaps \| Weighted Average
Derivative [Line Items]
Weighted Average Life (Years)	1 year 3 months 29 days	1 year 2 months 19 days

Average fixed interest rate related to the group of interest rate derivatives.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-5

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Average period remaining until maturity of derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

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Average variable interest rate related to the group of interest rate derivatives.

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Aggregate fair value of all derivative assets designated as hedging instruments. Includes instruments designated as cash flow hedges, fair value hedges, and hedges of net investments in foreign operations.

+ References

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Aggregate fair value of all derivative liabilities designated as hedging instruments. Includes instruments designated as cash flow hedges, fair value hedges, and hedges of net investments in foreign operations.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Nominal or face amount used to calculate payment on derivative.

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Fair value as of the balance sheet date of all interest rate derivative assets designated as cash flow hedging instruments.

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Fair value as of the balance sheet date of all interest rate derivative liabilities designated as cash flow hedging instruments.

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