ALLOWANCE FOR LOAN LOSSES AND CREDIT QUALITY - Aging Of The Recorded Investment In Past Due Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	$ 4,045,634	$ 3,897,455
30 to 89 Days Past Due	1,474	10,025
90 Days Past Due and Still Accruing	45	0
Nonaccrual	18,675	7,265
Total Past Due and Nonaccural	20,194	17,290
Total	4,065,828	3,914,745
Other Commercial Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	112,166	95,520
30 to 89 Days Past Due	0	0
Nonaccrual	0	0
Total Past Due and Nonaccural	0	0
Total	112,166	95,520
Other Commercial Loans | Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
90 Days Past Due and Still Accruing	0	0
Commercial and Industrial Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total	1,426,826	1,405,338
Commercial and Industrial Loans | Working capital lines of credit loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	703,737	684,191
30 to 89 Days Past Due	10	4,328
Nonaccrual	6,236	2,245
Total Past Due and Nonaccural	6,246	6,573
Total	709,983	690,764
Commercial and Industrial Loans | Working capital lines of credit loans | Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
90 Days Past Due and Still Accruing	0	0
Commercial and Industrial Loans | Non-working capital loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	710,557	709,629
30 to 89 Days Past Due	4	3,368
Nonaccrual	6,282	1,577
Total Past Due and Nonaccural	6,286	4,945
Total	716,843	714,574
Commercial and Industrial Loans | Non-working capital loans | Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
90 Days Past Due and Still Accruing	0	0
Commercial Real Estate and Multi-family Residential Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total	1,670,840	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	286,534	265,544
30 to 89 Days Past Due	0	0
Nonaccrual	0	0
Total Past Due and Nonaccural	0	0
Total	286,534	265,544
Commercial Real Estate and Multi-family Residential Loans | Construction and land development loans | Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
90 Days Past Due and Still Accruing	0	0
Commercial Real Estate and Multi-family Residential Loans | Owner occupied loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	569,303	583,214
30 to 89 Days Past Due	0	486
Nonaccrual	4,056	2,269
Total Past Due and Nonaccural	4,056	2,755
Total	573,359	585,969
Commercial Real Estate and Multi-family Residential Loans | Owner occupied loans | Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
90 Days Past Due and Still Accruing	0	0
Commercial Real Estate and Multi-family Residential Loans | Nonowner occupied loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	570,687	520,431
30 to 89 Days Past Due	0	57
Nonaccrual	0	0
Total Past Due and Nonaccural	0	57
Total	570,687	520,488
Commercial Real Estate and Multi-family Residential Loans | Nonowner occupied loans | Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
90 Days Past Due and Still Accruing	0	0
Commercial Real Estate and Multi-family Residential Loans | Multi-family loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	240,260	195,164
30 to 89 Days Past Due	0	0
Nonaccrual	0	0
Total Past Due and Nonaccural	0	0
Total	240,260	195,164
Commercial Real Estate and Multi-family Residential Loans | Multi-family loans | Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
90 Days Past Due and Still Accruing	0	0
Agri-business and Agricultural Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total	379,631	370,607
Agri-business and Agricultural Loans | Loans secured by farmland
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	173,959	177,080
30 to 89 Days Past Due	0	150
Nonaccrual	430	283
Total Past Due and Nonaccural	430	433
Total	174,389	177,513
Agri-business and Agricultural Loans | Loans secured by farmland | Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
90 Days Past Due and Still Accruing	0	0
Agri-business and Agricultural Loans | Loans for agricultural production
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	205,228	193,094
30 to 89 Days Past Due	0	0
Nonaccrual	14	0
Total Past Due and Nonaccural	14	0
Total	205,242	193,094
Agri-business and Agricultural Loans | Loans for agricultural production | Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
90 Days Past Due and Still Accruing	0	0
Consumer 1-4 Family Mortgage Loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Total	377,999	390,293
Consumer 1-4 Family Mortgage Loans | Closed end first mortgage loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	174,902	183,420
30 to 89 Days Past Due	1,099	1,370
90 Days Past Due and Still Accruing	45	0
Nonaccrual	827	671
Total Past Due and Nonaccural	1,971	2,041
Total	176,873	185,461
Consumer 1-4 Family Mortgage Loans | Open end and junior lien loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	187,255	188,320
30 to 89 Days Past Due	188	98
Nonaccrual	761	220
Total Past Due and Nonaccural	949	318
Total	188,204	188,638
Consumer 1-4 Family Mortgage Loans | Open end and junior lien loans | Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
90 Days Past Due and Still Accruing	0	0
Consumer 1-4 Family Mortgage Loans | Residential construction loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	12,870	16,194
30 to 89 Days Past Due	0	0
Nonaccrual	52	0
Total Past Due and Nonaccural	52	0
Total	12,922	16,194
Consumer 1-4 Family Mortgage Loans | Residential construction loans | Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
90 Days Past Due and Still Accruing	0	0
Consumer 1-4 Family Mortgage Loans | Other consumer loans
Financing Receivable, Recorded Investment, Aging [Abstract]
Loans Not Past Due	98,176	85,654
30 to 89 Days Past Due	173	168
Nonaccrual	17	0
Total Past Due and Nonaccural	190	168
Total	98,366	85,822
Consumer 1-4 Family Mortgage Loans | Other consumer loans | Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Aging [Abstract]
90 Days Past Due and Still Accruing	$ 0	$ 0