INCOME TAXES - Schedule of Deferred Tax Assets and Liabilities from Tax Effects of Temporary Differences (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Deferred tax assets:
Allowance for credit losses	$ 95	$ 91
Discounts on loans acquired in a business combination	8	10
Net operating loss/tax credit carryforwards	44	45
Deferred compensation	17	16
Securities impairment	2	2
Lease liability	68	60
Net unrealized securities losses	39	56
Other	22	34
Total	295	314
Valuation allowance	(34)	(32)
Total deferred tax assets	261	282
Total deferred tax assets
Loan costs	(13)	(10)
Depreciation	(16)	(8)
Prepaid expenses	(2)	(1)
Amortizable intangibles	(16)	(20)
Pension and other defined benefit plans	(13)	(10)
Lease financing	(68)	(40)
Mortgage servicing rights	(16)	(13)
Lease ROU asset	(58)	(57)
Other	(1)	(2)
Total deferred tax liabilities	(203)	(161)
Net deferred tax assets	$ 58	$ 121