LOANS - Total Loans Outstanding (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Jun. 30, 2023	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 4,874,496	$ 4,713,465
Percentage of loans receivable	100.00%	100.00%
Less: Allowance for credit losses	$ (72,105)	$ (72,606)	$ (72,058)	$ (67,239)	$ (67,523)	$ (67,773)
Net deferred loan fees	(3,531)	(3,069)
Loans, net	4,798,860	4,637,790
Total commercial loans | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 4,331,146	$ 4,217,824
Percentage of loans receivable	88.80%	89.50%
Total consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 543,350	$ 495,641
Percentage of loans receivable	11.20%	10.50%
Other consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 93,737	$ 88,075
Percentage of loans receivable	1.90%	1.90%
Commercial and industrial loans:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 1,402,220	$ 1,493,049
Percentage of loans receivable	28.80%	31.70%
Commercial and industrial loans: | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: Allowance for credit losses	$ (30,639)	$ (35,290)	(30,978)	(32,348)	(31,195)	(30,595)
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	$ 589,345	$ 650,948
Percentage of loans receivable	12.10%	13.80%
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	$ 812,875	$ 842,101
Percentage of loans receivable	16.70%	17.90%
Commercial real estate and multi-family residential loans:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 2,422,459	$ 2,179,094
Percentage of loans receivable	49.60%	46.20%
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	$ 633,920	$ 517,664
Percentage of loans receivable	13.00%	11.00%
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	$ 811,175	$ 758,091
Percentage of loans receivable	16.60%	16.00%
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	$ 740,783	$ 706,107
Percentage of loans receivable	15.20%	15.00%
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	$ 236,581	$ 197,232
Percentage of loans receivable	4.80%	4.20%
Agri-business and agricultural loans:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 380,528	$ 432,088
Percentage of loans receivable	7.80%	9.20%
Agri-business and agricultural loans: | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: Allowance for credit losses	$ (4,263)	$ (4,429)	$ (4,402)	$ (4,206)	$ (4,753)	$ (5,034)
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	$ 183,241	$ 201,200
Percentage of loans receivable	3.80%	4.30%
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	$ 197,287	$ 230,888
Percentage of loans receivable	4.00%	4.90%
Other commercial loans:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 125,939	$ 113,593
Percentage of loans receivable	2.60%	2.40%
Consumer 1-4 family mortgage loans:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable before allowance for credit loss	$ 449,613	$ 407,566
Percentage of loans receivable	9.30%	8.60%
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	$ 247,114	$ 212,742
Percentage of loans receivable	5.10%	4.50%
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	$ 189,611	$ 175,575
Percentage of loans receivable	3.90%	3.70%
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	$ 12,888	$ 19,249
Percentage of loans receivable	0.30%	0.40%