BORROWED FUNDS - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Principal balance	$ 12,500	$ 13,600
Unamortized deferred issuance costs and or discounts	85	74
Cumulative amount of fair value hedging adjustments included in the carrying amount of the hedged items	(8)	(17)
Short-term borrowed funds	0	505
Available borrowing capacity	74,000
FHLB advances and letters of credit | Secured Debt
Debt Instrument [Line Items]
Short-term borrowed funds	4,600	9,200
Pledged as collateral for FHLB borrowing capacity
Debt Instrument [Line Items]
Available borrowing capacity	$ 21,100	$ 15,900