ALLOWANCE FOR LOAN LOSSES AND CREDIT QUALITY - Aging Of The Recorded Investment In Past Due Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	$ 4,003,052	$ 3,897,455
30 to 89 Days Past Due	1,204	10,025
Nonaccrual	18,658	7,265
Total Past Due and Nonaccural	20,169	17,290
Total	4,023,221	3,914,745
Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	307	0
Other Commercial Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	99,969	95,520
30 to 89 Days Past Due	0	0
Nonaccrual	0	0
Total Past Due and Nonaccural	0	0
Total	99,969	95,520
Other Commercial Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	0	0
Other consumer loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	90,236	85,654
30 to 89 Days Past Due	138	168
Nonaccrual	0	0
Total Past Due and Nonaccural	138	168
Total	90,374	85,822
Other consumer loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	0	0
Commercial and Industrial Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total	1,432,397	1,405,338
Commercial and Industrial Loans | Working Capital Lines of Credit Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	724,404	684,191
30 to 89 Days Past Due	0	4,328
Nonaccrual	6,309	2,245
Total Past Due and Nonaccural	6,309	6,573
Total	730,713	690,764
Commercial and Industrial Loans | Working Capital Lines of Credit Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	0	0
Commercial and Industrial Loans | Non-working Capital Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	695,127	709,629
30 to 89 Days Past Due	42	3,368
Nonaccrual	6,515	1,577
Total Past Due and Nonaccural	6,557	4,945
Total	701,684	714,574
Commercial and Industrial Loans | Non-working Capital Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	0	0
Commercial Real Estate and Multi-family Residential Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total	1,678,386	1,567,165
Commercial Real Estate and Multi-family Residential Loans | Construction and Land Development Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	318,369	265,544
30 to 89 Days Past Due	0	0
Nonaccrual	0	0
Total Past Due and Nonaccural	0	0
Total	318,369	265,544
Commercial Real Estate and Multi-family Residential Loans | Construction and Land Development Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	0	0
Commercial Real Estate and Multi-family Residential Loans | Owner Occupied Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	552,276	583,214
30 to 89 Days Past Due	0	486
Nonaccrual	3,952	2,269
Total Past Due and Nonaccural	3,952	2,755
Total	556,228	585,969
Commercial Real Estate and Multi-family Residential Loans | Owner Occupied Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	0	0
Commercial Real Estate and Multi-family Residential Loans | Nonowner Occupied Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	544,778	520,431
30 to 89 Days Past Due	0	57
Nonaccrual	0	0
Total Past Due and Nonaccural	0	57
Total	544,778	520,488
Commercial Real Estate and Multi-family Residential Loans | Nonowner Occupied Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	0	0
Commercial Real Estate and Multi-family Residential Loans | Multifamily Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	259,011	195,164
30 to 89 Days Past Due	0	0
Nonaccrual	0	0
Total Past Due and Nonaccural	0	0
Total	259,011	195,164
Commercial Real Estate and Multi-family Residential Loans | Multifamily Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	0	0
Commercial Real Estate and Multi-family Residential Loans | Other Commercial Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total		585,969
Agri-business and Agricultural Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total	330,072	370,607
Agri-business and Agricultural Loans | Loans Secured By Farmland
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	175,604	177,080
30 to 89 Days Past Due	6	150
Nonaccrual	430	283
Total Past Due and Nonaccural	436	433
Total	176,040	177,513
Agri-business and Agricultural Loans | Loans Secured By Farmland | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	0	0
Agri-business and Agricultural Loans | Loans For Agricultural Production
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	154,017	193,094
30 to 89 Days Past Due	15	0
Nonaccrual	0	0
Total Past Due and Nonaccural	15	0
Total	154,032	193,094
Agri-business and Agricultural Loans | Loans For Agricultural Production | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	0	0
Agri-business and Agricultural Loans | Other Commercial Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total	99,969	95,520
Consumer 1-4 Family Mortgage Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total	392,023	390,293
Consumer 1-4 Family Mortgage Loans | Other Commercial Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total	90,374	85,822
Consumer 1-4 Family Mortgage Loans | Closed End First Mortgage Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	185,219	183,420
30 to 89 Days Past Due	850	1,370
Nonaccrual	675	671
Total Past Due and Nonaccural	1,832	2,041
Total	187,051	185,461
Consumer 1-4 Family Mortgage Loans | Closed End First Mortgage Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	307	0
Consumer 1-4 Family Mortgage Loans | Home Equity Mortgage Open Ended Revolving Lines
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	192,365	188,320
30 to 89 Days Past Due	101	98
Nonaccrual	777	220
Total Past Due and Nonaccural	878	318
Total	193,243	188,638
Consumer 1-4 Family Mortgage Loans | Home Equity Mortgage Open Ended Revolving Lines | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	0	0
Consumer 1-4 Family Mortgage Loans | Residential Construction and Land Development Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	11,677	16,194
30 to 89 Days Past Due	52	0
Nonaccrual	0	0
Total Past Due and Nonaccural	52	0
Total	11,729	16,194
Consumer 1-4 Family Mortgage Loans | Residential Construction and Land Development Loans | Greater than 90 Days Past Due
Financing Receivable, Recorded Investment, Aging [Abstract]
Total Past Due	$ 0	$ 0