GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of Core Deposit Intangibles, Customer Renewal Lists and Mortgage Servicing Rights (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 277	$ 276
Accumulated amortization	(241)	(225)
Net carrying amount	36	51
Core Deposit Intangibles
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	258	258
Accumulated amortization	(224)	(209)
Net carrying amount	34	49
Customer Renewal Lists
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	19	18
Accumulated amortization	(17)	(16)
Net carrying amount	$ 2	$ 2