COMPREHENSIVE INCOME - Components (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
COMPREHENSIVE INCOME
Unrealized holding gains (losses) on available-for-sale debt securities, Before-Tax Amount	$ 13,829	$ (14,865)	$ 10,243	$ (12,535)
Unrealized holding (losses) gains on available-for-sale debt securities, Income Tax Effect	(2,515)	3,123	(1,761)	2,632
Unrealized holding (losses) gains on available-for-sale debt securities, Net of Tax Amount	11,314	(11,742)	8,482	(9,903)
Reclassification adjustment for (gains) losses realized in income, Before-Tax Amount	0	0	0	(6)
Reclassification adjustment for gains (losses) realized in income, Income Tax Effect	0	0	0	1
Reclassification adjustment for (gains) losses realized in income. Net of Tax Amount	0	0	0	(5)
Other comprehensive (loss) income from available-for-sale debt securities, Before-Tax Amount	13,829	(14,865)	10,243	(12,541)
Other comprehensive loss (income) from available-for-sale debt securities, Income tax effect	(2,515)	3,123	(1,761)	2,633
Other comprehensive (loss) income from available-for-sale debt securities, Net-of-Tax Amount	11,314	(11,742)	8,482	(9,908)
Changes from plan amendments and actuarial gains and losses, Before-Tax Amount	0	0	394	(8)
Changes from plan amendments and actuarial gains and losses, Income Tax Effect			(83)	1
Changes from plan amendments and actuarial gains and losses, Net-of-Tax Amount			311	(7)
Amortization of prior service cost and net actuarial loss and curtailment gain included in net periodic benefit cost, Before-Tax Amount	(22)	(14)	(532)	(42)
Amortization of prior service cost and net actuarial loss and curtailment gain included in net periodic benefit cost, Income Tax Effect	5	3	112	9
Amortization of prior service cost and net actuarial loss and curtailment gain included in net periodic benefit cost, Net-of-Tax Amount	(17)	(11)	(420)	(33)
Other comprehensive loss on unfunded retirement obligations, Before-Tax Amount	(22)	(14)	(138)	(50)
Other comprehensive loss on unfunded retirement obligations, Income Tax Effect	5	3	29	10
Other comprehensive loss on unfunded retirement obligations, Net-of-Tax Amount	(17)	(11)	(109)	(40)
Total other comprehensive (income) loss, Before-Tax Amount	13,807	(14,879)	10,105	(12,591)
Total other comprehensive income (loss), Income Tax Effect	(2,510)	3,126	(1,732)	2,643
Total other comprehensive income (loss), Net-of-Tax Amount	$ 11,297	$ (11,753)	$ 8,373	$ (9,948)