ALLOWANCE FOR LOAN LOSSES AND CREDIT QUALITY - Credit Quality Indicators (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment
Total ending loans balance	$ 4,589,924	$ 4,065,828
Closed End First Mortgage Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance		176,873
Commercial and Industrial Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	1,837,747	1,426,826
Commercial and Industrial Loans [Member] | Working Capital Lines of Credit Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	592,640	709,983
Commercial and Industrial Loans [Member] | Non-working Capital Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	1,245,107	716,843
Commercial Real Estate and Multi-family Residential Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	1,857,820	1,670,840
Commercial Real Estate and Multi-family Residential Loans [Member] | Construction and Land Development Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	392,078	286,534
Commercial Real Estate and Multi-family Residential Loans [Member] | Owner Occupied Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	619,407	573,359
Commercial Real Estate and Multi-family Residential Loans [Member] | Nonowner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	567,027	570,687
Commercial Real Estate and Multi-family Residential Loans [Member] | Multifamily Loans
Financing Receivable, Recorded Investment
Total ending loans balance	279,308	240,260
Agri-business and Agricultural Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	338,164	379,631
Agri-business and Agricultural Loans [Member] | Loans Secured By Farmland
Financing Receivable, Recorded Investment
Total ending loans balance	150,448	174,389
Agri-business and Agricultural Loans [Member] | Loans For Agricultural Production
Financing Receivable, Recorded Investment
Total ending loans balance	187,716	205,242
Agri-business and Agricultural Loans [Member] | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	97,428	112,166
Consumer 1-4 Family Mortgage Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	353,724	377,999
Consumer 1-4 Family Mortgage Loans [Member] | Closed End First Mortgage Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	170,307	176,873
Consumer 1-4 Family Mortgage Loans [Member] | Open End And Junior Lien Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	172,452	188,204
Consumer 1-4 Family Mortgage Loans [Member] | Residential Construction and Land Development Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	10,965	12,922
Consumer 1-4 Family Mortgage Loans [Member] | Other Consumer Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	105,041	98,366
Pass
Financing Receivable, Recorded Investment
Total ending loans balance	3,995,113	3,490,863
Pass | Commercial and Industrial Loans [Member] | Working Capital Lines of Credit Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	526,206	631,728
Pass | Commercial and Industrial Loans [Member] | Non-working Capital Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	1,195,861	673,370
Pass | Commercial Real Estate and Multi-family Residential Loans [Member] | Construction and Land Development Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	392,078	286,534
Pass | Commercial Real Estate and Multi-family Residential Loans [Member] | Owner Occupied Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	579,800	535,496
Pass | Commercial Real Estate and Multi-family Residential Loans [Member] | Nonowner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	560,424	569,315
Pass | Commercial Real Estate and Multi-family Residential Loans [Member] | Multifamily Loans
Financing Receivable, Recorded Investment
Total ending loans balance	279,308	240,260
Pass | Agri-business and Agricultural Loans [Member] | Loans Secured By Farmland
Financing Receivable, Recorded Investment
Total ending loans balance	139,013	165,005
Pass | Agri-business and Agricultural Loans [Member] | Loans For Agricultural Production
Financing Receivable, Recorded Investment
Total ending loans balance	136,682	191,489
Pass | Agri-business and Agricultural Loans [Member] | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	97,428	112,166
Pass | Consumer 1-4 Family Mortgage Loans [Member] | Closed End First Mortgage Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	42,213	47,405
Pass | Consumer 1-4 Family Mortgage Loans [Member] | Open End And Junior Lien Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	9,058	10,845
Pass | Consumer 1-4 Family Mortgage Loans [Member] | Residential Construction and Land Development Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Pass | Consumer 1-4 Family Mortgage Loans [Member] | Other Consumer Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	37,042	27,250
Special Mention
Financing Receivable, Recorded Investment
Total ending loans balance	168,670	96,608
Special Mention | Commercial and Industrial Loans [Member] | Working Capital Lines of Credit Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	47,016	40,551
Special Mention | Commercial and Industrial Loans [Member] | Non-working Capital Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	25,294	18,782
Special Mention | Commercial Real Estate and Multi-family Residential Loans [Member] | Construction and Land Development Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Special Mention | Commercial Real Estate and Multi-family Residential Loans [Member] | Owner Occupied Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	27,945	14,804
Special Mention | Commercial Real Estate and Multi-family Residential Loans [Member] | Nonowner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	6,603	781
Special Mention | Commercial Real Estate and Multi-family Residential Loans [Member] | Multifamily Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Special Mention | Agri-business and Agricultural Loans [Member] | Loans Secured By Farmland
Financing Receivable, Recorded Investment
Total ending loans balance	10,778	7,952
Special Mention | Agri-business and Agricultural Loans [Member] | Loans For Agricultural Production
Financing Receivable, Recorded Investment
Total ending loans balance	51,034	13,738
Special Mention | Agri-business and Agricultural Loans [Member] | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Special Mention | Consumer 1-4 Family Mortgage Loans [Member] | Closed End First Mortgage Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Special Mention | Consumer 1-4 Family Mortgage Loans [Member] | Open End And Junior Lien Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Special Mention | Consumer 1-4 Family Mortgage Loans [Member] | Residential Construction and Land Development Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Special Mention | Consumer 1-4 Family Mortgage Loans [Member] | Other Consumer Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Substandard
Financing Receivable, Recorded Investment
Total ending loans balance	52,662	84,562
Substandard | Commercial and Industrial Loans [Member] | Working Capital Lines of Credit Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	19,159	37,278
Substandard | Commercial and Industrial Loans [Member] | Non-working Capital Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	18,747	19,381
Substandard | Commercial Real Estate and Multi-family Residential Loans [Member] | Construction and Land Development Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Substandard | Commercial Real Estate and Multi-family Residential Loans [Member] | Owner Occupied Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	11,662	23,059
Substandard | Commercial Real Estate and Multi-family Residential Loans [Member] | Nonowner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	591
Substandard | Commercial Real Estate and Multi-family Residential Loans [Member] | Multifamily Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Substandard | Agri-business and Agricultural Loans [Member] | Loans Secured By Farmland
Financing Receivable, Recorded Investment
Total ending loans balance	657	1,432
Substandard | Agri-business and Agricultural Loans [Member] | Loans For Agricultural Production
Financing Receivable, Recorded Investment
Total ending loans balance	0	15
Substandard | Agri-business and Agricultural Loans [Member] | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Substandard | Consumer 1-4 Family Mortgage Loans [Member] | Closed End First Mortgage Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	1,728	1,976
Substandard | Consumer 1-4 Family Mortgage Loans [Member] | Open End And Junior Lien Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	684	762
Substandard | Consumer 1-4 Family Mortgage Loans [Member] | Residential Construction and Land Development Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	25	51
Substandard | Consumer 1-4 Family Mortgage Loans [Member] | Other Consumer Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	17
Doubtful
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Commercial and Industrial Loans [Member] | Working Capital Lines of Credit Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Commercial and Industrial Loans [Member] | Non-working Capital Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Commercial Real Estate and Multi-family Residential Loans [Member] | Construction and Land Development Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Commercial Real Estate and Multi-family Residential Loans [Member] | Owner Occupied Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Commercial Real Estate and Multi-family Residential Loans [Member] | Nonowner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Commercial Real Estate and Multi-family Residential Loans [Member] | Multifamily Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Agri-business and Agricultural Loans [Member] | Loans Secured By Farmland
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Agri-business and Agricultural Loans [Member] | Loans For Agricultural Production
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Agri-business and Agricultural Loans [Member] | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Consumer 1-4 Family Mortgage Loans [Member] | Closed End First Mortgage Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Consumer 1-4 Family Mortgage Loans [Member] | Open End And Junior Lien Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Consumer 1-4 Family Mortgage Loans [Member] | Residential Construction and Land Development Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Consumer 1-4 Family Mortgage Loans [Member] | Other Consumer Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated
Financing Receivable, Recorded Investment
Total ending loans balance	373,479	393,795
Not Rated | Commercial and Industrial Loans [Member] | Working Capital Lines of Credit Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	259	426
Not Rated | Commercial and Industrial Loans [Member] | Non-working Capital Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	5,205	5,310
Not Rated | Commercial Real Estate and Multi-family Residential Loans [Member] | Construction and Land Development Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated | Commercial Real Estate and Multi-family Residential Loans [Member] | Owner Occupied Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated | Commercial Real Estate and Multi-family Residential Loans [Member] | Nonowner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated | Commercial Real Estate and Multi-family Residential Loans [Member] | Multifamily Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated | Agri-business and Agricultural Loans [Member] | Loans Secured By Farmland
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated | Agri-business and Agricultural Loans [Member] | Loans For Agricultural Production
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated | Agri-business and Agricultural Loans [Member] | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated | Consumer 1-4 Family Mortgage Loans [Member] | Closed End First Mortgage Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	126,366	127,492
Not Rated | Consumer 1-4 Family Mortgage Loans [Member] | Open End And Junior Lien Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	162,710	176,597
Not Rated | Consumer 1-4 Family Mortgage Loans [Member] | Residential Construction and Land Development Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	10,940	12,871
Not Rated | Consumer 1-4 Family Mortgage Loans [Member] | Other Consumer Loans [Member]
Financing Receivable, Recorded Investment
Total ending loans balance	$ 67,999	$ 71,099