ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Other Comprehensive Income (Loss), before Reclassification Adjustments and Tax [Abstract]
Unrealized gain (loss) on investment securities	$ (31,545)	$ (129,632)	$ 8,072	$ (312,111)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	(430)		(430)
Retirement obligation	0	0	0	0
Foreign currency translation	144	(27)	148	(16)
Total	(31,831)	(129,659)	7,790	(312,127)
Other Comprehensive Income (Loss) Reclassifications before Tax [Abstract]
Realized gain (loss) on securities available-for-sale	384	0	903	(3)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	0		0
Retirement obligation	(171)	(330)	(321)	(655)
Foreign currency translation	0	0	0	0
Total	213	(330)	582	(658)
Transactions Pre-tax
Unrealized gain (loss) on investment securities	(31,929)	(129,632)	7,169	(312,108)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax	(430)		(430)
Unfunded pension obligation	171	330	321	655
Foreign currency translation	144	(27)	148	(16)
Total	(32,044)	(129,329)	7,208	(311,469)
Transactions Tax-effect
Unrealized gain (loss) on investment securities	7,033	28,554	(1,580)	68,629
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax	(99)		(99)
Retirement obligation	(39)	(76)	(74)	(55)
Foreign currency translation	0	0	0	0
Total	7,093	28,478	(1,555)	68,574
Transactions Net of tax
Unrealized gain (loss) on investment securities	(24,896)	(101,078)	5,589	(243,479)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	(331)	0	(331)	0
Retirement obligation	132	254	247	600
Foreign currency translation	144	(27)	148	(16)
Total	(24,951)	(100,851)	5,653	(242,895)
Balances Net of tax
Unrealized gain (loss) on investment securities	(320,336)	(222,441)	(320,336)	(222,441)	$ (295,440)	$ (325,925)	$ (121,363)	$ 21,038
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax	(331)		(331)		0	0
Retirement obligation	(31,776)	(20,246)	(31,776)	(20,246)	(31,908)	(32,023)	(20,500)	(20,846)
Foreign currency translation	(567)	(641)	(567)	(641)	(711)	(715)	(614)	(625)
Accumulated other comprehensive loss	(353,010)	(243,328)	(353,010)	(243,328)	$ (328,059)	$ (358,663)	$ (142,477)	$ (433)
Accumulated other comprehensive income (loss)
Transactions Net of tax
Total	$ (24,951)	$ (100,851)	$ 5,653	$ (242,895)