ALLOWANCE FOR LOAN LOSSES AND CREDIT QUALITY - Credit Quality Indicators (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment
Total ending loans balance	$ 4,023,221	$ 3,914,745
Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	99,969	95,520
Commercial and Industrial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	1,432,397	1,405,338
Commercial and Industrial Loans | Working Capital Lines of Credit Loans
Financing Receivable, Recorded Investment
Total ending loans balance	730,713	690,764
Commercial and Industrial Loans | Non-working Capital Loans
Financing Receivable, Recorded Investment
Total ending loans balance	701,684	714,574
Commercial Real Estate and Multi-family Residential Loans
Financing Receivable, Recorded Investment
Total ending loans balance	1,678,386	1,567,165
Commercial Real Estate and Multi-family Residential Loans | Construction and Land Development Loans
Financing Receivable, Recorded Investment
Total ending loans balance	318,369	265,544
Commercial Real Estate and Multi-family Residential Loans | Owner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	556,228	585,969
Commercial Real Estate and Multi-family Residential Loans | Nonowner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	544,778	520,488
Commercial Real Estate and Multi-family Residential Loans | Multifamily Loans
Financing Receivable, Recorded Investment
Total ending loans balance	259,011	195,164
Commercial Real Estate and Multi-family Residential Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance		585,969
Agri-business and Agricultural Loans
Financing Receivable, Recorded Investment
Total ending loans balance	330,072	370,607
Agri-business and Agricultural Loans | Loans Secured By Farmland
Financing Receivable, Recorded Investment
Total ending loans balance	176,040	177,513
Agri-business and Agricultural Loans | Loans For Agricultural Production
Financing Receivable, Recorded Investment
Total ending loans balance	154,032	193,094
Agri-business and Agricultural Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	99,969	95,520
Consumer 1-4 Family Mortgage Loans
Financing Receivable, Recorded Investment
Total ending loans balance	392,023	390,293
Consumer 1-4 Family Mortgage Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	90,374	85,822
Consumer 1-4 Family Mortgage Loans | Closed End First Mortgage Loans
Financing Receivable, Recorded Investment
Total ending loans balance	187,051	185,461
Consumer 1-4 Family Mortgage Loans | Open End And Junior Lien Loans
Financing Receivable, Recorded Investment
Total ending loans balance	193,243	188,638
Consumer 1-4 Family Mortgage Loans | Residential Construction and Land Development Loans
Financing Receivable, Recorded Investment
Total ending loans balance	11,729	16,194
Pass
Financing Receivable, Recorded Investment
Total ending loans balance	3,411,196	3,324,054
Pass | Commercial and Industrial Loans | Working Capital Lines of Credit Loans
Financing Receivable, Recorded Investment
Total ending loans balance	635,786	618,612
Pass | Commercial and Industrial Loans | Non-working Capital Loans
Financing Receivable, Recorded Investment
Total ending loans balance	655,100	664,787
Pass | Commercial Real Estate and Multi-family Residential Loans | Construction and Land Development Loans
Financing Receivable, Recorded Investment
Total ending loans balance	318,369	264,900
Pass | Commercial Real Estate and Multi-family Residential Loans | Owner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	516,448
Pass | Commercial Real Estate and Multi-family Residential Loans | Nonowner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	542,717	517,356
Pass | Commercial Real Estate and Multi-family Residential Loans | Multifamily Loans
Financing Receivable, Recorded Investment
Total ending loans balance	259,011	194,948
Pass | Commercial Real Estate and Multi-family Residential Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance		541,734
Pass | Agri-business and Agricultural Loans | Loans Secured By Farmland
Financing Receivable, Recorded Investment
Total ending loans balance	163,731	166,623
Pass | Agri-business and Agricultural Loans | Loans For Agricultural Production
Financing Receivable, Recorded Investment
Total ending loans balance	143,123	183,189
Pass | Agri-business and Agricultural Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	99,969	95,516
Pass | Consumer 1-4 Family Mortgage Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	16,036	12,700
Pass | Consumer 1-4 Family Mortgage Loans | Closed End First Mortgage Loans
Financing Receivable, Recorded Investment
Total ending loans balance	49,839	54,879
Pass | Consumer 1-4 Family Mortgage Loans | Open End And Junior Lien Loans
Financing Receivable, Recorded Investment
Total ending loans balance	11,067	8,810
Pass | Consumer 1-4 Family Mortgage Loans | Residential Construction and Land Development Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Special Mention
Financing Receivable, Recorded Investment
Total ending loans balance	114,781	101,418
Special Mention | Commercial and Industrial Loans | Working Capital Lines of Credit Loans
Financing Receivable, Recorded Investment
Total ending loans balance	56,133	43,240
Special Mention | Commercial and Industrial Loans | Non-working Capital Loans
Financing Receivable, Recorded Investment
Total ending loans balance	19,066	15,992
Special Mention | Commercial Real Estate and Multi-family Residential Loans | Construction and Land Development Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	353
Special Mention | Commercial Real Estate and Multi-family Residential Loans | Owner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	16,162
Special Mention | Commercial Real Estate and Multi-family Residential Loans | Nonowner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	1,456	2,491
Special Mention | Commercial Real Estate and Multi-family Residential Loans | Multifamily Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	216
Special Mention | Commercial Real Estate and Multi-family Residential Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance		21,864
Special Mention | Agri-business and Agricultural Loans | Loans Secured By Farmland
Financing Receivable, Recorded Investment
Total ending loans balance	11,055	9,107
Special Mention | Agri-business and Agricultural Loans | Loans For Agricultural Production
Financing Receivable, Recorded Investment
Total ending loans balance	10,909	8,155
Special Mention | Agri-business and Agricultural Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Special Mention | Consumer 1-4 Family Mortgage Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Special Mention | Consumer 1-4 Family Mortgage Loans | Closed End First Mortgage Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Special Mention | Consumer 1-4 Family Mortgage Loans | Open End And Junior Lien Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Special Mention | Consumer 1-4 Family Mortgage Loans | Residential Construction and Land Development Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Substandard
Financing Receivable, Recorded Investment
Total ending loans balance	88,986	85,232
Substandard | Commercial and Industrial Loans | Working Capital Lines of Credit Loans
Financing Receivable, Recorded Investment
Total ending loans balance	38,538	28,563
Substandard | Commercial and Industrial Loans | Non-working Capital Loans
Financing Receivable, Recorded Investment
Total ending loans balance	22,364	27,548
Substandard | Commercial Real Estate and Multi-family Residential Loans | Construction and Land Development Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	291
Substandard | Commercial Real Estate and Multi-family Residential Loans | Owner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	23,618
Substandard | Commercial Real Estate and Multi-family Residential Loans | Nonowner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	605	641
Substandard | Commercial Real Estate and Multi-family Residential Loans | Multifamily Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Substandard | Commercial Real Estate and Multi-family Residential Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance		22,371
Substandard | Agri-business and Agricultural Loans | Loans Secured By Farmland
Financing Receivable, Recorded Investment
Total ending loans balance	1,254	1,783
Substandard | Agri-business and Agricultural Loans | Loans For Agricultural Production
Financing Receivable, Recorded Investment
Total ending loans balance	0	1,750
Substandard | Agri-business and Agricultural Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Substandard | Consumer 1-4 Family Mortgage Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	44
Substandard | Consumer 1-4 Family Mortgage Loans | Closed End First Mortgage Loans
Financing Receivable, Recorded Investment
Total ending loans balance	1,830	2,021
Substandard | Consumer 1-4 Family Mortgage Loans | Open End And Junior Lien Loans
Financing Receivable, Recorded Investment
Total ending loans balance	777	220
Substandard | Consumer 1-4 Family Mortgage Loans | Residential Construction and Land Development Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Commercial and Industrial Loans | Working Capital Lines of Credit Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Commercial and Industrial Loans | Non-working Capital Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Commercial Real Estate and Multi-family Residential Loans | Construction and Land Development Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Commercial Real Estate and Multi-family Residential Loans | Owner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0
Doubtful | Commercial Real Estate and Multi-family Residential Loans | Nonowner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Commercial Real Estate and Multi-family Residential Loans | Multifamily Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Commercial Real Estate and Multi-family Residential Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance		0
Doubtful | Agri-business and Agricultural Loans | Loans Secured By Farmland
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Agri-business and Agricultural Loans | Loans For Agricultural Production
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Agri-business and Agricultural Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Consumer 1-4 Family Mortgage Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Consumer 1-4 Family Mortgage Loans | Closed End First Mortgage Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Consumer 1-4 Family Mortgage Loans | Open End And Junior Lien Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Doubtful | Consumer 1-4 Family Mortgage Loans | Residential Construction and Land Development Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated
Financing Receivable, Recorded Investment
Total ending loans balance	408,258	404,041
Not Rated | Commercial and Industrial Loans | Working Capital Lines of Credit Loans
Financing Receivable, Recorded Investment
Total ending loans balance	256	349
Not Rated | Commercial and Industrial Loans | Non-working Capital Loans
Financing Receivable, Recorded Investment
Total ending loans balance	5,154	6,247
Not Rated | Commercial Real Estate and Multi-family Residential Loans | Construction and Land Development Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated | Commercial Real Estate and Multi-family Residential Loans | Owner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0
Not Rated | Commercial Real Estate and Multi-family Residential Loans | Nonowner Occupied Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated | Commercial Real Estate and Multi-family Residential Loans | Multifamily Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated | Commercial Real Estate and Multi-family Residential Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance		0
Not Rated | Agri-business and Agricultural Loans | Loans Secured By Farmland
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated | Agri-business and Agricultural Loans | Loans For Agricultural Production
Financing Receivable, Recorded Investment
Total ending loans balance	0	0
Not Rated | Agri-business and Agricultural Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	0	4
Not Rated | Consumer 1-4 Family Mortgage Loans | Other Commercial Loans
Financing Receivable, Recorded Investment
Total ending loans balance	74,338	73,078
Not Rated | Consumer 1-4 Family Mortgage Loans | Closed End First Mortgage Loans
Financing Receivable, Recorded Investment
Total ending loans balance	135,382	128,561
Not Rated | Consumer 1-4 Family Mortgage Loans | Open End And Junior Lien Loans
Financing Receivable, Recorded Investment
Total ending loans balance	181,399	179,608
Not Rated | Consumer 1-4 Family Mortgage Loans | Residential Construction and Land Development Loans
Financing Receivable, Recorded Investment
Total ending loans balance	$ 11,729	$ 16,194