ALLOWANCE FOR CREDIT LOSSES AND CREDIT QUALITY - Aging Of The Amortized Cost In Past Due Loans (Details) $ in Thousands	Sep. 30, 2021 USD ($)
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	$ 4,239,453
Total Nonaccrual	30,978
Nonaccrual With No Allowance For Credit Loss	1,373
Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	4,208,475
Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	4,238,195
30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	1,240
Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	18
Commercial and industrial loans | Working capital lines of credit loans
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	659,274
Total Nonaccrual	14,181
Nonaccrual With No Allowance For Credit Loss	1
Commercial and industrial loans | Working capital lines of credit loans | Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	645,093
Commercial and industrial loans | Working capital lines of credit loans | Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	659,160
Commercial and industrial loans | Working capital lines of credit loans | 30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	114
Commercial and industrial loans | Working capital lines of credit loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	0
Commercial and industrial loans | Non-working capital loans
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	779,665
Total Nonaccrual	8,956
Nonaccrual With No Allowance For Credit Loss	232
Commercial and industrial loans | Non-working capital loans | Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	770,709
Commercial and industrial loans | Non-working capital loans | Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	779,551
Commercial and industrial loans | Non-working capital loans | 30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	114
Commercial and industrial loans | Non-working capital loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	0
Commercial real estate and multi-family residential loans | Construction and land development loans
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	377,371
Total Nonaccrual	0
Nonaccrual With No Allowance For Credit Loss	0
Commercial real estate and multi-family residential loans | Construction and land development loans | Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	377,371
Commercial real estate and multi-family residential loans | Construction and land development loans | Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	377,371
Commercial real estate and multi-family residential loans | Construction and land development loans | 30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	0
Commercial real estate and multi-family residential loans | Construction and land development loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	0
Commercial real estate and multi-family residential loans | Owner occupied loans
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	740,245
Total Nonaccrual	3,822
Nonaccrual With No Allowance For Credit Loss	986
Commercial real estate and multi-family residential loans | Owner occupied loans | Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	736,423
Commercial real estate and multi-family residential loans | Owner occupied loans | Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	740,245
Commercial real estate and multi-family residential loans | Owner occupied loans | 30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	0
Commercial real estate and multi-family residential loans | Owner occupied loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	0
Commercial real estate and multi-family residential loans | Nonowner occupied loans
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	581,618
Total Nonaccrual	3,358
Nonaccrual With No Allowance For Credit Loss	0
Commercial real estate and multi-family residential loans | Nonowner occupied loans | Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	578,260
Commercial real estate and multi-family residential loans | Nonowner occupied loans | Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	581,618
Commercial real estate and multi-family residential loans | Nonowner occupied loans | 30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	0
Commercial real estate and multi-family residential loans | Nonowner occupied loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	0
Commercial real estate and multi-family residential loans | Multifamily loans
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	252,549
Total Nonaccrual	0
Nonaccrual With No Allowance For Credit Loss	0
Commercial real estate and multi-family residential loans | Multifamily loans | Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	252,549
Commercial real estate and multi-family residential loans | Multifamily loans | Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	252,549
Commercial real estate and multi-family residential loans | Multifamily loans | 30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	0
Commercial real estate and multi-family residential loans | Multifamily loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	0
Agri-business and agricultural loans | Loans secured by farmland
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	152,060
Total Nonaccrual	145
Nonaccrual With No Allowance For Credit Loss	0
Agri-business and agricultural loans | Loans secured by farmland | Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	151,915
Agri-business and agricultural loans | Loans secured by farmland | Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	152,060
Agri-business and agricultural loans | Loans secured by farmland | 30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	0
Agri-business and agricultural loans | Loans secured by farmland | Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	0
Agri-business and agricultural loans | Loans for agricultural production
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	172,054
Total Nonaccrual	0
Nonaccrual With No Allowance For Credit Loss	0
Agri-business and agricultural loans | Loans for agricultural production | Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	172,054
Agri-business and agricultural loans | Loans for agricultural production | Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	172,054
Agri-business and agricultural loans | Loans for agricultural production | 30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	0
Agri-business and agricultural loans | Loans for agricultural production | Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	0
Agri-business and agricultural loans | Other commercial loans
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	83,263
Total Nonaccrual	0
Nonaccrual With No Allowance For Credit Loss	0
Agri-business and agricultural loans | Other commercial loans | Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	83,263
Agri-business and agricultural loans | Other commercial loans | Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	83,263
Agri-business and agricultural loans | Other commercial loans | 30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	0
Agri-business and agricultural loans | Other commercial loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	0
Consumer 1-4 family loans | Closed end first mortgage loans
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	173,393
Total Nonaccrual	100
Nonaccrual With No Allowance For Credit Loss	56
Consumer 1-4 family loans | Closed end first mortgage loans | Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	173,293
Consumer 1-4 family loans | Closed end first mortgage loans | Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	172,515
Consumer 1-4 family loans | Closed end first mortgage loans | 30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	860
Consumer 1-4 family loans | Closed end first mortgage loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	18
Consumer 1-4 family loans | Open end and junior lien loans
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	163,523
Total Nonaccrual	98
Nonaccrual With No Allowance For Credit Loss	98
Consumer 1-4 family loans | Open end and junior lien loans | Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	163,425
Consumer 1-4 family loans | Open end and junior lien loans | Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	163,489
Consumer 1-4 family loans | Open end and junior lien loans | 30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	34
Consumer 1-4 family loans | Open end and junior lien loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	0
Consumer 1-4 family loans | Residential construction loans
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	12,491
Total Nonaccrual	0
Nonaccrual With No Allowance For Credit Loss	0
Consumer 1-4 family loans | Residential construction loans | Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	12,491
Consumer 1-4 family loans | Residential construction loans | Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	12,491
Consumer 1-4 family loans | Residential construction loans | 30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	0
Consumer 1-4 family loans | Residential construction loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	0
Consumer 1-4 family loans | Other consumer loans
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	91,947
Total Nonaccrual	318
Nonaccrual With No Allowance For Credit Loss	0
Consumer 1-4 family loans | Other consumer loans | Total Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	91,629
Consumer 1-4 family loans | Other consumer loans | Loans Not Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	91,829
Consumer 1-4 family loans | Other consumer loans | 30-89 Days Past Due
Financing Receivable, Amortized Cost, Aging [Abstract]
Financing receivable, before allowance for credit loss, amortized cost	118
Consumer 1-4 family loans | Other consumer loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Amortized Cost, Aging [Abstract]
Greater than 89 Days Past Due and Accruing	$ 0