DERIVATIVE FINANCIAL INSTRUMENTS - Hedging Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Derivatives, Fair Value [Line Items]
Notional Value	$ 42,311	$ 45,809
Asset derivatives included in accrued income and other assets
Total contracts	502	610
Liability derivatives included in accrued expenses and other liabilities
Total contracts	508	668
Accrued income and other assets
Asset derivatives included in accrued income and other assets
Total contracts	502	610
Accrued expenses and other liabilities
Liability derivatives included in accrued expenses and other liabilities
Total contracts	508	668
Interest rate contracts | Accrued income and other assets
Asset derivatives included in accrued income and other assets
Interest rate contracts designated as hedging instruments	122	24
Interest rate contracts | Accrued expenses and other liabilities
Liability derivatives included in accrued expenses and other liabilities
Interest rate contracts designated as hedging instruments	38	0
Foreign exchange contracts | Accrued income and other assets
Asset derivatives included in accrued income and other assets
Interest rate contracts designated as hedging instruments	0	0
Foreign exchange contracts | Accrued expenses and other liabilities
Liability derivatives included in accrued expenses and other liabilities
Interest rate contracts designated as hedging instruments	2	5
Credit contracts | Accrued income and other assets
Asset derivatives included in accrued income and other assets
Derivative instruments not designated as hedging instruments, asset	3	2
Credit contracts | Accrued expenses and other liabilities
Liability derivatives included in accrued expenses and other liabilities
Derivative credit and equity contracts not designated as hedging instruments, liability	0	0
Derivatives designated as Hedging Instruments | Interest rate contracts | Accrued income and other assets
Derivatives, Fair Value [Line Items]
Notional Value	42,136	45,634
Derivatives designated as Hedging Instruments | Foreign exchange contracts | Accrued income and other assets
Derivatives, Fair Value [Line Items]
Notional Value	266	250
Derivatives not designated as Hedging Instruments | Accrued income and other assets
Derivatives, Fair Value [Line Items]
Notional Value	97,988	95,461
Derivatives not designated as Hedging Instruments | Interest rate contracts | Accrued income and other assets
Derivatives, Fair Value [Line Items]
Notional Value	47,557	42,359
Asset derivatives included in accrued income and other assets
Interest rate contracts not designated as hedging instruments	261	456
Derivatives not designated as Hedging Instruments | Interest rate contracts | Accrued expenses and other liabilities
Liability derivatives included in accrued expenses and other liabilities
Interest rate contracts not designated as hedging instruments	389	580
Derivatives not designated as Hedging Instruments | Foreign exchange contracts | Accrued income and other assets
Derivatives, Fair Value [Line Items]
Notional Value	6,287	5,465
Asset derivatives included in accrued income and other assets
Foreign exchange contracts not designated as hedging instruments	61	79
Derivatives not designated as Hedging Instruments | Foreign exchange contracts | Accrued expenses and other liabilities
Liability derivatives included in accrued expenses and other liabilities
Foreign exchange contracts not designated as hedging instruments	52	54
Derivatives not designated as Hedging Instruments | Equity contracts | Accrued income and other assets
Derivatives, Fair Value [Line Items]
Notional Value	897	823
Asset derivatives included in accrued income and other assets
Commodities contracts not designated as hedging instruments	32	20
Derivatives not designated as Hedging Instruments | Equity contracts | Accrued expenses and other liabilities
Liability derivatives included in accrued expenses and other liabilities
Commodities contracts not designated as hedging instruments	6	2
Derivatives not designated as Hedging Instruments | Commodities contracts | Accrued income and other assets
Derivatives, Fair Value [Line Items]
Notional Value	685	683
Asset derivatives included in accrued income and other assets
Derivative instruments not designated as hedging instruments, asset	23	29
Derivatives not designated as Hedging Instruments | Commodities contracts | Accrued expenses and other liabilities
Liability derivatives included in accrued expenses and other liabilities
Derivative credit and equity contracts not designated as hedging instruments, liability	21	27
Derivatives not designated as Hedging Instruments | Credit contracts | Accrued income and other assets
Derivatives, Fair Value [Line Items]
Notional Value	$ 160	$ 247