COMPREHENSIVE INCOME (LOSS) - Components (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
COMPREHENSIVE INCOME (LOSS)
Unrealized holding gains (losses) on available-for-sale debt securities	$ (6,663)	$ (20,018)	$ 2,330	$ (52,043)
Unrealized holding gains (losses) on available-for-sale debt securities, Income Tax Effect	1,397	4,202	(491)	10,928
Unrealized holding gains (losses) on available-for-sale debt securities, Net of Tax Amount	(5,266)	(15,816)	1,839	(41,115)
Reclassification adjustment for (gains) realized in income	1	1	(6)	(1)
Reclassification adjustment for (gains) losses realized in income, Income Tax Effect	0	0	1	0
Reclassification adjustment for (gains) losses realized in income. Net of Tax Amount	1	1	(5)	(1)
Other comprehensive income (loss) from available-for-sale debt securities, Before-Tax Amount	(6,662)	(20,017)	2,324	(52,044)
Other comprehensive income (loss) on available-for-sale debt securities, Income tax effect	1,397	4,202	(490)	10,928
Other comprehensive income (loss) from available-for-sale debt securities, Net-of-Tax Amount	(5,265)	(15,815)	1,834	(41,116)
Changes from plan amendments and actuarial gains and losses, Before-Tax Amount	0	0	(8)	133
Changes from plan amendments and actuarial gains and losses, Income Tax Effect			1	(27)
Changes from plan amendments and actuarial gains and losses, Net-of-Tax Amount			(7)	106
Amortization of prior service cost and net actuarial loss included in net periodic benefit cost, Before-Tax Amount	(14)	(11)	(28)	(22)
Amortization of prior service cost and net actuarial loss included in net periodic benefit cost, Income Tax Effect	3	2	6	4
Amortization of prior service cost and net actuarial loss included in net periodic benefit cost, Net-of-Tax Amount	(11)	(9)	(22)	(18)
Other comprehensive (loss) income on pension and postretirement obligations	(14)	(11)	(36)	111
Other comprehensive income (loss) on unfunded retirement obligations, Income Tax Effect	3	2	7	(23)
Other comprehensive income (loss) on unfunded retirement obligations, Net-of-Tax Amount	(11)	(9)	(29)	88
Total Other comprehensive (loss) income before income tax	(6,676)	(20,028)	2,288	(51,933)
Total other comprehensive income (loss), Income Tax Effect	1,400	4,204	(483)	10,905
Total other comprehensive income (loss), Net-of-Tax Amount	$ (5,276)	$ (15,824)	$ 1,805	$ (41,028)