ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Accumulated Other Comprehensive income (loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Accumulated other comprehensive income (loss), net of tax:
Balance	$ 1,226,225	$ 1,169,583
Total other comprehensive income (loss), net of tax	6,113	(4,259)
Balance	1,239,371	1,191,253
Total Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss), net of tax:
Balance	(91,579)	(94,379)
Other comprehensive income (loss) before reclassifications	4,178	(5,330)
Amounts reclassified from accumulated other comprehensive income (loss)	1,935	1,071
Total other comprehensive income (loss), net of tax	6,113	(4,259)
Balance	(85,466)	(98,638)
Securities
Accumulated other comprehensive income (loss), net of tax:
Balance	(90,242)	(100,870)
Other comprehensive income (loss) before reclassifications	2,360	(4,313)
Amounts reclassified from accumulated other comprehensive income (loss)	490	1,551
Total other comprehensive income (loss), net of tax	2,850	(2,762)
Balance	(87,392)	(103,632)
Defined Benefit Plans
Accumulated other comprehensive income (loss), net of tax:
Balance	(6,430)	(5,266)
Other comprehensive income (loss) before reclassifications	361	155
Amounts reclassified from accumulated other comprehensive income (loss)	(216)	(260)
Total other comprehensive income (loss), net of tax	145	(105)
Balance	(6,285)	(5,371)
Derivatives
Accumulated other comprehensive income (loss), net of tax:
Balance	5,093	11,757
Other comprehensive income (loss) before reclassifications	1,457	(1,172)
Amounts reclassified from accumulated other comprehensive income (loss)	1,661	(220)
Total other comprehensive income (loss), net of tax	3,118	(1,392)
Balance	$ 8,211	$ 10,365