INCOME TAXES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Examination [Line Items]
Unrealized losses on investments in debt and equity	$ 186,775,000	$ 212,222,000
Postretirement benefit obligations	1,500,000	1,500,000
Unrealized gains on available-for-sale securities		212,200,000
Deferred income tax (benefit) expense	0
Deferred tax asset	230,262,000	250,756,000
Alternative minimum tax credits	500,000
Proceeds from bank-owned life insurance surrender, including non-cash income	65,500,000
Proceeds from Bank-Owned Life Insurance, surrender, taxable gain	22,600,000
Income tax charge on BOLI	7,100,000
Unrecognized tax benefits	0
Amortization of low-income housing credit investments reflected as income tax expense	3,900,000	4,800,000	$ 3,600,000
Affordable housing tax benefits	1,900,000
Carrying value of investment in affordable housing credits	87,100,000	$ 69,000,000
General Business Tax Credit Carryforward
Income Tax Examination [Line Items]
Tax credit	4,700,000
Federal
Income Tax Examination [Line Items]
Net operating loss carryforwards	13,000,000
Federal net operating loss	$ 2,800,000