LOANS (Allowance for credit losses on financing receivables) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	$ 18,237		$ 8,171
Collectively Evaluated for Credit Losses	101,700		62,224
Total	119,937	$ 97,350	70,395	$ 63,850	$ 62,639	$ 61,963
Loans Individually Evaluated for Credit Losses	62,663		87,052
Loans Collectively Evaluated for Credit Losses	9,184,167		8,280,865
Total	9,246,830		8,367,917
Commercial and industrial | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	2,068		6,276
Collectively Evaluated for Credit Losses	30,463		24,511
Total	32,531	32,463	30,787	27,680	27,250	26,306
Loans Individually Evaluated for Credit Losses	14,731		31,814
Loans Collectively Evaluated for Credit Losses	2,349,669		2,498,995
Total	2,364,400		2,530,809
Commercial and industrial | Paycheck Protection Program ("PPP")
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	0
Collectively Evaluated for Credit Losses	0
Total	0	0	0
Loans Individually Evaluated for Credit Losses	0
Loans Collectively Evaluated for Credit Losses	1,124,430
Total	1,124,430		0
Commercial and industrial | Owner occupied commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	13,446		351
Collectively Evaluated for Credit Losses	9,956		7,863
Total	23,402	10,336	8,214	6,182	6,330	6,525
Loans Individually Evaluated for Credit Losses	21,588		9,468
Loans Collectively Evaluated for Credit Losses	1,411,683		1,463,236
Total	1,433,271		1,472,704
Commercial and industrial | Non-owner occupied commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	29		33
Collectively Evaluated for Credit Losses	10,133		7,769
Total	10,162	8,321	7,802	7,482	7,126	7,430
Loans Individually Evaluated for Credit Losses	3,550		1,730
Loans Collectively Evaluated for Credit Losses	1,540,073		1,494,147
Total	1,543,623		1,495,877
Commercial and industrial | Real estate construction
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	51		0
Collectively Evaluated for Credit Losses	28,616		11,599
Total	28,667	22,951	11,599	10,010	9,994	9,679
Loans Individually Evaluated for Credit Losses	258		685
Loans Collectively Evaluated for Credit Losses	1,115,585		1,026,396
Total	1,115,843		1,027,081
Agricultural and agricultural real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	2,086		916
Collectively Evaluated for Credit Losses	3,615		4,757
Total	5,701	4,797	5,673	5,986	5,518	4,914
Loans Individually Evaluated for Credit Losses	17,065		18,554
Loans Collectively Evaluated for Credit Losses	503,708		547,283
Total	520,773		565,837
Residential real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	240		176
Collectively Evaluated for Credit Losses	9,064		1,328
Total	9,304	8,725	1,504	1,592	1,623	1,813
Loans Individually Evaluated for Credit Losses	4,783		20,678
Loans Collectively Evaluated for Credit Losses	730,979		811,599
Total	735,762		832,277
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	317		419
Collectively Evaluated for Credit Losses	9,853		4,397
Total	10,170	$ 9,757	4,816	$ 4,918	$ 4,798	$ 5,296
Loans Individually Evaluated for Credit Losses	688		4,123
Loans Collectively Evaluated for Credit Losses	408,040		439,209
Total	$ 408,728		$ 443,332