ALLOWANCE FOR CREDIT LOSSES AND CREDIT QUALITY - Credit Quality Indicators (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	$ 4,649,156
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	3,997,245
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	251,891
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	34,264
Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	365,756
Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	1,784,926
Commercial Real Estate and Multi-family Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	1,892,572
Agri-business and Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	429,662
Consumer 1-4 Family Mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	344,699
Working capital lines of credit loans | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	626,099
Working capital lines of credit loans | Commercial and Industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	535,071
Working capital lines of credit loans | Commercial and Industrial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	81,095
Working capital lines of credit loans | Commercial and Industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	9,718
Working capital lines of credit loans | Commercial and Industrial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Working capital lines of credit loans | Commercial and Industrial | Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	215
Non-working capital loans | Commercial and Industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	1,158,827
Non-working capital loans | Commercial and Industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	1,111,989
Non-working capital loans | Commercial and Industrial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	26,523
Non-working capital loans | Commercial and Industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	14,820
Non-working capital loans | Commercial and Industrial | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Non-working capital loans | Commercial and Industrial | Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	5,495
Construction and land development loans | Commercial Real Estate and Multi-family Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	361,664
Construction and land development loans | Commercial Real Estate and Multi-family Residential | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	361,664
Construction and land development loans | Commercial Real Estate and Multi-family Residential | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Construction and land development loans | Commercial Real Estate and Multi-family Residential | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Construction and land development loans | Commercial Real Estate and Multi-family Residential | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Construction and land development loans | Commercial Real Estate and Multi-family Residential | Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Owner occupied loans | Commercial Real Estate and Multi-family Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	647,574
Owner occupied loans | Commercial Real Estate and Multi-family Residential | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	608,845
Owner occupied loans | Commercial Real Estate and Multi-family Residential | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	31,355
Owner occupied loans | Commercial Real Estate and Multi-family Residential | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	7,374
Owner occupied loans | Commercial Real Estate and Multi-family Residential | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Owner occupied loans | Commercial Real Estate and Multi-family Residential | Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Nonowner occupied loans | Commercial Real Estate and Multi-family Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	579,050
Nonowner occupied loans | Commercial Real Estate and Multi-family Residential | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	547,790
Nonowner occupied loans | Commercial Real Estate and Multi-family Residential | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	31,260
Nonowner occupied loans | Commercial Real Estate and Multi-family Residential | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Nonowner occupied loans | Commercial Real Estate and Multi-family Residential | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Nonowner occupied loans | Commercial Real Estate and Multi-family Residential | Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Multi-family loans | Commercial Real Estate and Multi-family Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	304,284
Multi-family loans | Commercial Real Estate and Multi-family Residential | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	282,031
Multi-family loans | Commercial Real Estate and Multi-family Residential | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	22,253
Multi-family loans | Commercial Real Estate and Multi-family Residential | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Multi-family loans | Commercial Real Estate and Multi-family Residential | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Multi-family loans | Commercial Real Estate and Multi-family Residential | Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Loans secured by farmland | Agri-business and Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	195,363
Loans secured by farmland | Agri-business and Agricultural | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	183,983
Loans secured by farmland | Agri-business and Agricultural | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	10,728
Loans secured by farmland | Agri-business and Agricultural | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	652
Loans secured by farmland | Agri-business and Agricultural | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Loans secured by farmland | Agri-business and Agricultural | Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Loans for agricultural production | Agri-business and Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	234,299
Loans for agricultural production | Agri-business and Agricultural | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	185,875
Loans for agricultural production | Agri-business and Agricultural | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	48,424
Loans for agricultural production | Agri-business and Agricultural | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Loans for agricultural production | Agri-business and Agricultural | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Loans for agricultural production | Agri-business and Agricultural | Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Other commercial loans | Agri-business and Agricultural
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	93,912
Other commercial loans | Agri-business and Agricultural | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	93,912
Other commercial loans | Agri-business and Agricultural | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Other commercial loans | Agri-business and Agricultural | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Other commercial loans | Agri-business and Agricultural | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Other commercial loans | Agri-business and Agricultural | Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Closed end first mortgage loans | Consumer 1-4 Family Mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	167,501
Closed end first mortgage loans | Consumer 1-4 Family Mortgage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	40,682
Closed end first mortgage loans | Consumer 1-4 Family Mortgage | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Closed end first mortgage loans | Consumer 1-4 Family Mortgage | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	1,695
Closed end first mortgage loans | Consumer 1-4 Family Mortgage | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Closed end first mortgage loans | Consumer 1-4 Family Mortgage | Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	125,124
Open end and junior lien loans | Consumer 1-4 Family Mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	165,236
Open end and junior lien loans | Consumer 1-4 Family Mortgage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	8,424
Open end and junior lien loans | Consumer 1-4 Family Mortgage | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Open end and junior lien loans | Consumer 1-4 Family Mortgage | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	5
Open end and junior lien loans | Consumer 1-4 Family Mortgage | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Open end and junior lien loans | Consumer 1-4 Family Mortgage | Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	156,807
Residential construction loans | Consumer 1-4 Family Mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	11,962
Residential construction loans | Consumer 1-4 Family Mortgage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Residential construction loans | Consumer 1-4 Family Mortgage | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Residential construction loans | Consumer 1-4 Family Mortgage | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Residential construction loans | Consumer 1-4 Family Mortgage | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Residential construction loans | Consumer 1-4 Family Mortgage | Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	11,962
Total consumer loans | Consumer 1-4 Family Mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	103,385
Total consumer loans | Consumer 1-4 Family Mortgage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	36,979
Total consumer loans | Consumer 1-4 Family Mortgage | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	253
Total consumer loans | Consumer 1-4 Family Mortgage | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Total consumer loans | Consumer 1-4 Family Mortgage | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	0
Total consumer loans | Consumer 1-4 Family Mortgage | Not Rated
Financing Receivable, Credit Quality Indicator [Line Items]
Total ending loans balance	$ 66,153