LOANS (Allowance for credit losses on financing receivables) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	$ 10,729		$ 9,426
Collectively Evaluated for Credit Losses	106,804		122,180
Total	117,533	$ 120,726	131,606	$ 103,377	$ 119,937	$ 70,395
Loans Individually Evaluated for Credit Losses	58,921		57,230
Loans Collectively Evaluated for Credit Losses	9,795,986		9,965,821
Total	9,854,907		10,023,051
Commercial and industrial | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	4,710		4,077
Collectively Evaluated for Credit Losses	23,198		34,741
Total	27,908	31,332	38,818	34,581	32,518	34,207
Loans Individually Evaluated for Credit Losses	15,524		16,578
Loans Collectively Evaluated for Credit Losses	2,522,845		2,518,221
Total	2,538,369		2,534,799
Commercial and industrial | Paycheck Protection Program ("PPP")
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	0		0
Collectively Evaluated for Credit Losses	0		0
Total	0	0	0	0	0	0
Loans Individually Evaluated for Credit Losses	0		0
Loans Collectively Evaluated for Credit Losses	409,247		957,785
Total	409,247		957,785
Commercial and industrial | Owner occupied commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	110		111
Collectively Evaluated for Credit Losses	19,018		19,890
Total	19,128	19,990	20,001	11,229	23,402	7,921
Loans Individually Evaluated for Credit Losses	10,166		11,174
Loans Collectively Evaluated for Credit Losses	2,125,061		1,765,232
Total	2,135,227		1,776,406
Commercial and industrial | Non-owner occupied commercial real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	2,847		3,250
Collectively Evaluated for Credit Losses	19,268		17,623
Total	22,115	22,828	20,873	12,127	10,161	7,584
Loans Individually Evaluated for Credit Losses	19,314		13,490
Loans Collectively Evaluated for Credit Losses	2,001,173		1,907,991
Total	2,020,487		1,921,481
Commercial and industrial | Real estate construction
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	0		0
Collectively Evaluated for Credit Losses	23,698		20,080
Total	23,698	19,580	20,080	20,787	28,667	8,677
Loans Individually Evaluated for Credit Losses	0		0
Loans Collectively Evaluated for Credit Losses	814,001		863,220
Total	814,001		863,220
Agricultural and agricultural real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	3,062		1,988
Collectively Evaluated for Credit Losses	3,264		5,141
Total	6,326	7,160	7,129	5,342	5,701	5,680
Loans Individually Evaluated for Credit Losses	13,917		15,453
Loans Collectively Evaluated for Credit Losses	670,753		699,073
Total	684,670		714,526
Residential real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	0		0
Collectively Evaluated for Credit Losses	9,238		11,935
Total	9,238	9,741	11,935	9,671	9,304	1,504
Loans Individually Evaluated for Credit Losses	0		535
Loans Collectively Evaluated for Credit Losses	840,356		839,907
Total	840,356		840,442
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually Evaluated for Credit Losses	0		0
Collectively Evaluated for Credit Losses	9,120		12,770
Total	9,120	$ 10,095	12,770	$ 9,640	$ 10,184	$ 4,822
Loans Individually Evaluated for Credit Losses	0		0
Loans Collectively Evaluated for Credit Losses	412,550		414,392
Total	$ 412,550		$ 414,392