ACCUMULATED OTHER COMPREHENSIVE INCOME - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net securities gains	$ 0	$ 753
Other expense	3,239	2,244
Income tax expense	4,539	5,030
Net income	23,642	22,983
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income	(27)	550
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains and Losses on Available- for-Sales Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net securities gains		753
Income tax expense		(158)
Net income		595
Reclassification out of Accumulated Other Comprehensive Income | Defined Benefit Pension Items
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense	(36)	(60)
Income tax expense	9	15
Net income	$ (27)	$ (45)