BORROWED FUNDS - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Principal balance	$ 11,300	$ 12,500
Unamortized deferred issuance costs and or discounts	71	85
Cumulative amount of fair value hedging adjustments included in the carrying amount of the hedged items		(8)
Short-term borrowed funds	58	0
Available borrowing capacity	75,200
FHLB advances and letters of credit | Secured Debt
Debt Instrument [Line Items]
Short-term borrowed funds	7,100	4,600
Federal Home Loan Bank Advances
Debt Instrument [Line Items]
Available borrowing capacity	$ 22,100	$ 21,100