SHAREHOLDERS’ EQUITY AND COMPENSATION PLANS - Pre-tax and After-tax Changes in the Components of Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Reclassification Adjustments, after Tax [Abstract]
Change in unrealized gain on available-for-sale debt securities, before tax	$ (10,479)	$ 125	$ (21,226)	$ 28,741
Change in unrealized gain on available-for-sale debt securities, tax	(2,609)	31	(5,285)	7,099
Change in unrealized gain on available-for-sale debt securities, after tax	(7,870)	94	(15,941)	21,642
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax [Abstract]
Reclassification adjustment for realized (gain) loss on sale of available-for-sale debt securities, before tax	0	(417)	0	(421)
Reclassification adjustment for realized (gain) loss on sale of available-for-sale debt securities, tax	0	(103)	0	(104)
Reclassification adjustment for realized (gain) loss on sale of available-for-sale debt securities, after tax	0	314	0	317
Other Comprehensive Loss, Held-to-maturity Security, OTTI, after Tax and Adjustments [Abstract]
Reclassification of (gain) loss on held-to-maturity securities, before tax	(1,072)	(936)	(3,716)	(1,580)
Reclassification of (gain) loss on held-to-maturity securities, tax	(267)	(231)	(925)	(390)
Reclassification of (gain) loss on held-to-maturity securities, after tax	(805)	(705)	(2,791)	(1,190)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax, Parent [Abstract]
Change in unrealized loss on cash flow hedges arising during the period, before tax	12	146	867	(8,296)
Change in unrealized loss on cash flow hedges arising during the period, tax	3	36	216	(2,049)
Change in unrealized loss on cash flow hedges arising during the period, after tax	9	110	651	(6,247)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract]
Reclassification of loss on cash flow hedges, before tax	395	683	1,149	1,157
Reclassification of loss on cash flow hedges, tax	99	169	286	286
Reclassification of loss on cash flow hedges, after tax	(296)	(514)	(863)	(871)
OCI, Net of Tax [Abstract]
Total other comprehensive income, before tax	(11,144)	(399)	(22,926)	19,601
Total other comprehensive income, tax	(2,774)	(98)	(5,708)	4,842
Total other comprehensive income (loss), after-tax	$ (8,370)	$ (301)	$ (17,218)	$ 14,759