ALLOWANCE FOR CREDIT LOSSES AND CREDIT QUALITY - Aging Of The Recorded Investment In Past Due Loans (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	$ 4,649,156
Nonaccrual	11,986
Total Past Due and Nonaccrual	13,369
Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	4,635,787
30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	1,267
Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	116
Commercial and industrial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	1,784,926
Commercial and industrial loans | Working capital lines of credit loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	626,099
Nonaccrual	606
Total Past Due and Nonaccrual	606
Commercial and industrial loans | Working capital lines of credit loans | Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	625,493
Commercial and industrial loans | Working capital lines of credit loans | 30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Commercial and industrial loans | Working capital lines of credit loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Commercial and industrial loans | Non-working capital loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	1,158,827
Nonaccrual	5,287
Total Past Due and Nonaccrual	5,287
Commercial and industrial loans | Non-working capital loans | Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	1,153,540
Commercial and industrial loans | Non-working capital loans | 30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Commercial and industrial loans | Non-working capital loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Commercial real estate and multi-family residential loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	1,892,572
Commercial real estate and multi-family residential loans | Construction and land development loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	361,664
Nonaccrual	0
Total Past Due and Nonaccrual	0
Commercial real estate and multi-family residential loans | Construction and land development loans | Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	361,664
Commercial real estate and multi-family residential loans | Construction and land development loans | 30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Commercial real estate and multi-family residential loans | Construction and land development loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Commercial real estate and multi-family residential loans | Owner occupied loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	647,574
Nonaccrual	5,047
Total Past Due and Nonaccrual	5,047
Commercial real estate and multi-family residential loans | Owner occupied loans | Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	642,527
Commercial real estate and multi-family residential loans | Owner occupied loans | 30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Commercial real estate and multi-family residential loans | Owner occupied loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Commercial real estate and multi-family residential loans | Nonowner occupied loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	579,050
Nonaccrual	0
Total Past Due and Nonaccrual	0
Commercial real estate and multi-family residential loans | Nonowner occupied loans | Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	579,050
Commercial real estate and multi-family residential loans | Nonowner occupied loans | 30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Commercial real estate and multi-family residential loans | Nonowner occupied loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Commercial real estate and multi-family residential loans | Multifamily loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	304,284
Nonaccrual	0
Total Past Due and Nonaccrual	0
Commercial real estate and multi-family residential loans | Multifamily loans | Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	304,284
Commercial real estate and multi-family residential loans | Multifamily loans | 30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Commercial real estate and multi-family residential loans | Multifamily loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Agri-business and agricultural loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	429,662
Agri-business and agricultural loans | Loans secured by farmland
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	195,363
Nonaccrual	428
Total Past Due and Nonaccrual	428
Agri-business and agricultural loans | Loans secured by farmland | Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	194,935
Agri-business and agricultural loans | Loans secured by farmland | 30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Agri-business and agricultural loans | Loans secured by farmland | Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Agri-business and agricultural loans | Loans for agricultural production
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	234,299
Nonaccrual	0
Total Past Due and Nonaccrual	108
Agri-business and agricultural loans | Loans for agricultural production | Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	234,191
Agri-business and agricultural loans | Loans for agricultural production | 30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	108
Agri-business and agricultural loans | Loans for agricultural production | Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Agri-business and agricultural loans | Other commercial loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	93,912
Nonaccrual	0
Total Past Due and Nonaccrual	0
Agri-business and agricultural loans | Other commercial loans | Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	93,912
Agri-business and agricultural loans | Other commercial loans | 30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Agri-business and agricultural loans | Other commercial loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Consumer 1-4 family loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	344,699
Consumer 1-4 family loans | Closed end first mortgage loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	167,501
Nonaccrual	613
Total Past Due and Nonaccrual	1,606
Consumer 1-4 family loans | Closed end first mortgage loans | Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	165,895
Consumer 1-4 family loans | Closed end first mortgage loans | 30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	877
Consumer 1-4 family loans | Closed end first mortgage loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	116
Consumer 1-4 family loans | Open end and junior lien loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	165,236
Nonaccrual	5
Total Past Due and Nonaccrual	142
Consumer 1-4 family loans | Open end and junior lien loans | Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	165,094
Consumer 1-4 family loans | Open end and junior lien loans | 30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	137
Consumer 1-4 family loans | Open end and junior lien loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Consumer 1-4 family loans | Residential construction loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	11,962
Nonaccrual	0
Total Past Due and Nonaccrual	0
Consumer 1-4 family loans | Residential construction loans | Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	11,962
Consumer 1-4 family loans | Residential construction loans | 30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Consumer 1-4 family loans | Residential construction loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Consumer 1-4 family loans | Other consumer loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	103,385
Nonaccrual	0
Total Past Due and Nonaccrual	145
Consumer 1-4 family loans | Other consumer loans | Loans Not Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	103,240
Consumer 1-4 family loans | Other consumer loans | 30-89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	145
Consumer 1-4 family loans | Other consumer loans | Greater than 89 Days Past Due and Accruing
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	0
Consumer 1-4 family loans | Other consumer loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans past due	$ 103,385