ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Schedule of Changes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 2,034,770	$ 1,912,571	$ 1,875,645
Other comprehensive income (loss) before reclassifications	57,629	(293,798)
Amounts reclassified from accumulated other comprehensive income (loss)	5,552	(466)
Period change	63,181	(294,264)	(19,723)
Ending balance	2,247,713	2,034,770	1,912,571
Total
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(239,151)	55,113	74,836
Period change	63,181	(294,264)	(19,723)
Ending balance	(175,970)	(239,151)	55,113
Unrealized Gains (Losses) on Securities Available for Sale
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(234,495)	59,774
Other comprehensive income (loss) before reclassifications	55,366	(293,326)
Amounts reclassified from accumulated other comprehensive income (loss)	5,475	(943)
Period change	60,841	(294,269)
Ending balance	(173,654)	(234,495)	59,774
Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	130	(660)
Other comprehensive income (loss) before reclassifications	(142)	378
Amounts reclassified from accumulated other comprehensive income (loss)	12	412
Period change	(130)	790
Ending balance	0	130	(660)
Unrealized Gains (Losses) on Defined Benefit Plans
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(4,786)	(4,001)
Other comprehensive income (loss) before reclassifications	2,405	(850)
Amounts reclassified from accumulated other comprehensive income (loss)	65	65
Period change	2,470	(785)
Ending balance	$ (2,316)	$ (4,786)	$ (4,001)