DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of Derivative Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Asset Fair Value
Asset Fair Value	$ 660	$ 640
Less: gross amounts offset in the Consolidated Balance Sheets, Asset Fair Value	0	0
Derivative assets	660	640
Less: amounts subject to master netting agreements, Asset Fair Value	(48)	(97)
Less: cash collateral pledged (received) subject to master netting agreements	(539)	(405)
Total net derivative fair value, Asset Fair Value	73	138
Liability Fair Value
Liability Fair Value	(625)	(636)
Less: gross amounts offset in the Consolidated Balance Sheets, Liability Fair Value	0	0
Derivative liability	(625)	(636)
Less: amounts subject to master netting agreements, Asset Liability Value	48	97
Less: cash collateral pledged (received) subject to master netting agreements	2	39
Total net derivative fair value, Liability Fair Value	(575)	(500)
Variation margin, amount reducing derivative asset	83	66
Variation margin, amount reducing derivative liability	22	37
Qualifying Hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	4,584	815
Asset Fair Value
Asset Fair Value	1	0
Liability Fair Value
Liability Fair Value	0	0
Derivative instruments and hedges, assets	14	4
Derivative instruments and hedges, liabilities	0	0
Qualifying Hedges | Fair Value Hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	1,084	815
Asset Fair Value
Asset Fair Value	0	0
Liability Fair Value
Liability Fair Value	0	0
Qualifying Hedges | Interest rate contracts | Fair Value Hedges | Time deposits
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	334	0
Asset Fair Value
Asset Fair Value	0	0
Liability Fair Value
Liability Fair Value	0	0
Qualifying Hedges | Interest rate contracts | Fair Value Hedges | Long-term borrowings
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	750	815
Asset Fair Value
Asset Fair Value	0	0
Liability Fair Value
Liability Fair Value	0	0
Qualifying Hedges | Interest rate contracts | Cash Flow Hedges | Loans
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	3,500	0
Asset Fair Value
Asset Fair Value	1	0
Liability Fair Value
Liability Fair Value	0	0
Non-qualifying Hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	35,394	34,673
Asset Fair Value
Asset Fair Value	659	640
Liability Fair Value
Liability Fair Value	(625)	(636)
Non-qualifying Hedges | Interest rate contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	26,235	24,548
Asset Fair Value
Asset Fair Value	491	530
Liability Fair Value
Liability Fair Value	(516)	(518)
Non-qualifying Hedges | Foreign currency forward contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	7,843	9,142
Asset Fair Value
Asset Fair Value	152	104
Liability Fair Value
Liability Fair Value	(108)	(117)
Non-qualifying Hedges | Foreign exchange spot contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	177	179
Liability Fair Value
Net fair value	0	0
Non-qualifying Hedges | Other contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount	1,316	983
Asset Fair Value
Asset Fair Value	16	6
Liability Fair Value
Liability Fair Value	$ (1)	$ (1)