ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance	$ 1,192,620	$ 701,096
Total other comprehensive (loss) income, net of tax	(43,199)	6,455
Balance	1,155,287	1,172,824
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance	(6,181)	(5,924)
Other comprehensive (loss) income before reclassifications	(42,695)	7,565
Amounts reclassified from accumulated other comprehensive loss	(504)	(1,110)
Total other comprehensive (loss) income, net of tax	(43,199)	6,455
Balance	(49,380)	531
Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance	(7,864)	12,694
Other comprehensive (loss) income before reclassifications	(48,075)	(10,570)
Amounts reclassified from accumulated other comprehensive loss	116	(822)
Total other comprehensive (loss) income, net of tax	(47,959)	(11,392)
Balance	(55,823)	1,302
Defined Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance	(1,306)	(6,086)
Other comprehensive (loss) income before reclassifications	683	1,659
Amounts reclassified from accumulated other comprehensive loss	(641)	(288)
Total other comprehensive (loss) income, net of tax	42	1,371
Balance	(1,264)	(4,715)
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance	2,989	(12,532)
Other comprehensive (loss) income before reclassifications	4,697	16,476
Amounts reclassified from accumulated other comprehensive loss	21
Total other comprehensive (loss) income, net of tax	4,718	16,476
Balance	$ 7,707	$ 3,944