COMPREHENSIVE (LOSS) INCOME - Components (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
COMPREHENSIVE (LOSS) INCOME
Unrealized holding losses on available-for-sale debt securities	$ (25,880)	$ (3,608)	$ (77,923)	$ (6,781)
Unrealized holding losses on available-for-sale debt securities, Income Tax Effect	5,437	759	16,365	1,425
Unrealized holding losses on available-for-sale debt securities, Net of Tax Amount	(20,443)	(2,849)	(61,558)	(5,356)
Reclassification adjustment for (gains) realized in income	(20)	(23)	(21)	(25)
Reclassification adjustment for (gains) losses realized in income, Income Tax Effect	4	5	4	5
Reclassification adjustment for (gains) losses realized in income. Net of Tax Amount	(16)	(18)	(17)	(20)
Other comprehensive loss from available-for-sale debt securities, Before-Tax Amount	(25,900)	(3,631)	(77,944)	(6,806)
Other comprehensive loss on available-for-sale debt securities, income tax effect	5,441	764	16,369	1,430
Other comprehensive loss from available-for-sale debt securities, Net-of-Tax Amount	(20,459)	(2,867)	(61,575)	(5,376)
Changes from plan amendments and actuarial gains and losses, Before-Tax Amount	0	0	133	(5)
Changes from plan amendments and actuarial gains and losses, Income Tax Effect			(27)	1
Changes from plan amendments and actuarial gains and losses, Net-of-Tax Amount			106	(4)
Amortization of prior service cost and net actuarial loss included in net periodic benefit cost, Before-Tax Amount	(9)	(5)	(31)	(13)
Amortization of prior service cost and net actuarial loss included in net periodic benefit cost, Income Tax Effect	1	1	5	3
Amortization of prior service cost and net actuarial loss included in net periodic benefit cost, Net-of-Tax Amount	(8)	(4)	(26)	(10)
Other comprehensive (loss) income on pension and postretirement obligations	(9)	(5)	102	(18)
Other comprehensive income (loss) on unfunded retirement obligations, Income Tax Effect			(22)	4
Other comprehensive income (loss) on unfunded retirement obligations, Net-of-Tax Amount			80	(14)
Other comprehensive loss before income tax	(25,909)	(3,636)	(77,842)	(6,824)
Total other comprehensive income (loss), Income Tax Effect	5,442	765	16,347	1,434
Total other comprehensive income (loss), Net-of-Tax Amount	$ (20,467)	$ (2,871)	$ (61,495)	$ (5,390)