GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of Core Deposit Intangibles, Customer Renewal Lists and Mortgage Servicing Rights (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 276	$ 276
Accumulated amortization	(225)	(207)
Net carrying amount	51	69
Core Deposit Intangibles
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	258	258
Accumulated amortization	(209)	(192)
Net carrying amount	49	66
Customer Renewal Lists
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	18	18
Accumulated amortization	(16)	(15)
Net carrying amount	$ 2	$ 3