ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Summary of Accumulated Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 585,364	$ 508,955
Current Period Change	9,814	15,721
Income Tax Effect	(2,682)	(4,331)
Ending balance	616,938	519,158
Accumulated Other Comprehensive Loss, net of income taxes
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(86,004)	(108,707)
Current Period Change	9,814	15,721
Income Tax Effect	(2,682)	(4,331)
Ending balance	(78,872)	(97,317)
Unrealized gains (losses) on benefits plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(1,481)	(1,652)
Current Period Change	43	48
Income Tax Effect	(11)	(13)
Ending balance	(1,449)	(1,617)
Unrealized gains (losses) on available for sale securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(74,348)	(95,539)
Current Period Change	9,176	15,185
Income Tax Effect	(2,508)	(4,184)
Ending balance	(67,680)	(84,538)
Unaccreted unrealized loss on securities transferred to held-to-maturity
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(10,175)	(11,516)
Current Period Change	595	488
Income Tax Effect	(163)	(134)
Ending balance	$ (9,743)	$ (11,162)