BORROWED FUNDS - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Short-term borrowed funds	$ 3	$ 74
Hedging basis adjustments	1,839	1,509
Available borrowing capacity	63,300
FHLB advances and letters of credit | Secured Debt
Debt Instrument [Line Items]
Short-term borrowed funds	15,700	2,300
Pledged as collateral for FHLB borrowing capacity
Debt Instrument [Line Items]
Available borrowing capacity	11,500	15,900
Parent company
Debt Instrument [Line Items]
Principal balance	3,400	3,200
Unamortized deferred issuance costs and or discounts	75	80
CBNA and Other Subsidiaries
Debt Instrument [Line Items]
Principal balance	12,600	3,800
Unamortized deferred issuance costs and or discounts	10	7
Hedging basis adjustments	$ (27)	$ 42