CHANGE IN ACCUMULATED OTHER COMPREHENSIVE LOSS - Schedule of Components of Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income taxes	$ (21,202)	$ (20,941)
Income before taxes	86,925	83,603
Reclassification out of Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	3,620	4,079
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Net change in investment securities available-for-sale
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of net unrealized losses to income during the period	4,827	5,481
Income taxes	(1,158)	(1,315)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	3,669	4,166
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Prior service credits
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service credits	(19)	(19)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Actuarial gains
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Actuarial gains	(45)	(43)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Amortization of defined benefit pension plan-related items:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income taxes	15	15
Income before taxes	(64)	(62)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(49)	(47)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Net unrealized gains on terminated cash flow hedges:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of net unrealized losses to income during the period	0	(52)
Income taxes	0	12
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 0	$ (40)