LOANS - Total Loans Outstanding (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 5,000,757	$ 4,919,997
Percentage of loans receivable	100.00%	100.00%
Less: Allowance for credit losses	$ (73,180)	$ (71,972)	$ (71,215)	$ (72,606)
Net deferred loan fees	(3,198)	(3,463)
Loans, net	4,924,379	4,844,562
Total commercial loans | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 4,442,872	$ 4,367,788
Percentage of loans receivable	88.80%	88.80%
Total consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 557,885	$ 552,209
Percentage of loans receivable	11.20%	11.20%
Other consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 97,369	$ 96,022
Percentage of loans receivable	2.00%	1.90%
Commercial and industrial loans:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 1,477,276	$ 1,420,764
Percentage of loans receivable	29.50%	28.90%
Commercial and industrial loans: | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: Allowance for credit losses	$ (30,720)	$ (30,338)	(31,190)	(35,290)
Commercial and industrial loans: | Working capital lines of credit loans | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 646,459	$ 604,893
Percentage of loans receivable	12.90%	12.30%
Commercial and industrial loans: | Non-working capital loans | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 830,817	$ 815,871
Percentage of loans receivable	16.60%	16.60%
Commercial real estate and multi-family residential loans:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 2,477,442	$ 2,437,534
Percentage of loans receivable	49.60%	49.50%
Commercial real estate and multi-family residential loans: | Construction and land development loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 659,712	$ 634,435
Percentage of loans receivable	13.20%	12.90%
Commercial real estate and multi-family residential loans: | Owner occupied loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 833,410	$ 825,464
Percentage of loans receivable	16.70%	16.80%
Commercial real estate and multi-family residential loans: | Nonowner occupied loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 744,346	$ 724,101
Percentage of loans receivable	14.90%	14.70%
Commercial real estate and multi-family residential loans: | Multifamily loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 239,974	$ 253,534
Percentage of loans receivable	4.80%	5.10%
Agri-business and agricultural loans:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 367,852	$ 388,764
Percentage of loans receivable	7.30%	7.90%
Agri-business and agricultural loans: | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: Allowance for credit losses	$ (4,112)	$ (4,150)	$ (4,621)	$ (4,429)
Agri-business and agricultural loans: | Loans secured by farmland | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 167,271	$ 162,890
Percentage of loans receivable	3.30%	3.30%
Agri-business and agricultural loans: | Loans for agricultural production | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 200,581	$ 225,874
Percentage of loans receivable	4.00%	4.60%
Other commercial loans:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 120,302	$ 120,726
Percentage of loans receivable	2.40%	2.50%
Consumer 1-4 family mortgage loans:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 460,516	$ 456,187
Percentage of loans receivable	9.20%	9.30%
Consumer 1-4 family mortgage loans: | Closed end first mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 260,633	$ 258,103
Percentage of loans receivable	5.20%	5.20%
Consumer 1-4 family mortgage loans: | Open end and junior lien loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 188,927	$ 189,663
Percentage of loans receivable	3.80%	3.90%
Consumer 1-4 family mortgage loans: | Residential construction and land development loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 10,956	$ 8,421
Percentage of loans receivable	0.20%	0.20%