LOANS (Total Loans Outstanding) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	100.00%	100.00%
Total Commercial And Consumer Loans	$ 3,940,652	$ 3,916,326
Less: Allowance for loan losses	(49,562)	(48,453)	$ (45,627)	$ (47,121)
Net deferred loan fees	(1,642)	(1,581)
Loans, net	$ 3,889,448	$ 3,866,292
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	88.10%	87.90%
Total Commercial And Consumer Loans	$ 3,471,292	$ 3,441,184
Multifamily Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Commercial And Consumer Loans	$ 240,939	$ 195,604
Other consumer loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	2.10%	2.20%
Total Commercial And Consumer Loans	$ 84,650	$ 86,064
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	11.90%	12.10%
Total Commercial And Consumer Loans	$ 469,360	$ 475,142
Commercial and Industrial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: Allowance for loan losses	$ (24,030)	$ (22,518)	(20,725)	(21,097)
Commercial and Industrial Loans [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	36.20%	35.90%
Total Commercial And Consumer Loans	$ 1,427,342	$ 1,405,379
Commercial and Industrial Loans [Member] | Working Capital Lines Of Credit Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	18.40%	17.60%
Total Commercial And Consumer Loans	$ 726,895	$ 690,620
Commercial and Industrial Loans [Member] | Non-working Capital Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	17.80%	18.30%
Total Commercial And Consumer Loans	$ 700,447	$ 714,759
Commercial Real Estate and Multi-family Residential Loans [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	41.40%	40.10%
Total Commercial And Consumer Loans	$ 1,629,622	$ 1,569,635
Commercial Real Estate and Multi-family Residential Loans [Member] | Construction and Land Development Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	7.50%	6.80%
Total Commercial And Consumer Loans	$ 293,818	$ 266,805
Commercial Real Estate and Multi-family Residential Loans [Member] | Owner Occupied Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	14.10%	15.00%
Total Commercial And Consumer Loans	$ 557,296	$ 586,325
Commercial Real Estate and Multi-family Residential Loans [Member] | Nonowner Occupied Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	13.70%	13.30%
Total Commercial And Consumer Loans	$ 537,569	$ 520,901
Commercial Real Estate and Multi-family Residential Loans [Member] | Multifamily Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	6.10%	5.00%
Agri-business and Agricultural Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Less: Allowance for loan losses	$ (4,146)	$ (4,305)	$ (4,848)	$ (4,920)
Agri-business and Agricultural Loans [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	7.70%	9.50%
Total Commercial And Consumer Loans	$ 302,307	$ 370,513
Agri-business and Agricultural Loans [Member] | Loans Secured By Farmland [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	3.60%	4.60%
Total Commercial And Consumer Loans	$ 139,645	$ 177,503
Agri-business and Agricultural Loans [Member] | Loans For Agricultural Production [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	4.10%	4.90%
Total Commercial And Consumer Loans	$ 162,662	$ 193,010
Other Commercial Loans [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	2.80%	2.40%
Total Commercial And Consumer Loans	$ 112,021	$ 95,657
Total Consumer 1 To 4 Family Mortgage Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	9.80%	9.90%
Total Commercial And Consumer Loans	$ 384,710	$ 389,078
Total Consumer 1 To 4 Family Mortgage Loans [Member] | Closed End First Mortgage Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	4.80%	4.70%
Total Commercial And Consumer Loans	$ 188,777	$ 185,822
Total Consumer 1 To 4 Family Mortgage Loans [Member] | Open End And Junior Lien Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	4.70%	4.80%
Total Commercial And Consumer Loans	$ 182,791	$ 187,030
Total Consumer 1 To 4 Family Mortgage Loans [Member] | Residential Construction and Land Development Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Total commercial loans	0.30%	0.40%
Total Commercial And Consumer Loans	$ 13,142	$ 16,226