CREDIT QUALITY ASSESSMENT - Allowance for Credit Loss Activity (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 120,865	$ 136,242	$ 136,242
Provision/ (credit) for credit losses - loans	3,331	(18,945)	(13,894)
Loan charge-offs	(1,620)	(171)	(2,614)
Loan recoveries	520	487	1,131
Net (charge-offs)/ recoveries	(1,100)	316	(1,483)
Balance at period end	123,096	117,613	$ 120,865
Provision/ (credit) for credit losses	2,388	(21,536)
Unfunded commitments
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision/ (credit) for credit losses	$ (900)	$ (2,600)