GOODWILL AND INTANGIBLE ASSETS - Intangible assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Finite-lived intangible assets
Gross carrying amount	$ 74,832	$ 74,832
Accumulated amortization	(58,724)	(53,966)
Total	16,108	20,866
Amortization of intangible assets	4,758	5,410	$ 5,855
Core deposit intangibles
Finite-lived intangible assets
Gross carrying amount	58,914	58,913
Accumulated amortization	(48,287)	(44,723)
Total	10,627	14,190
Customer relationship intangibles
Finite-lived intangible assets
Gross carrying amount	15,918	15,919
Accumulated amortization	(10,437)	(9,243)
Total	$ 5,481	$ 6,676