ALLOWANCE FOR LOAN LOSSES (Allowance for Credit Losses by Loan Category) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	$ 70,395	$ 61,963	$ 55,686
Purchased Credit Deteriorated Allowance	12,313
Loans charged-off	(32,722)	(13,590)	(21,285)
Recoveries	3,804	5,365	3,549
Provision	65,745	16,657	24,013
Balance at end of year	131,606	70,395	61,963
Impact of ASU 2016-13 adoption on January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	12,071
Balance at end of year		12,071
Adjusted balance at January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	82,466
Loans charged-off		(13,590)
Recoveries		5,365
Provision		16,657
Balance at end of year		82,466
Commercial and industrial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	34,207	29,958
Balance at end of year	38,818	34,207	29,958
Commercial and industrial | Commercial and industrial | Impact of ASU 2016-13 adoption on January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	(272)
Balance at end of year		(272)
Commercial and industrial | Commercial and industrial | Adjusted balance at January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	33,935
Purchased Credit Deteriorated Allowance	1,707
Loans charged-off	(14,974)	(7,129)
Recoveries	1,277	2,462
Provision	16,873	8,916
Balance at end of year		33,935
Commercial and industrial | Paycheck Protection Program ("PPP")
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	0	0
Balance at end of year	0	0	0
Commercial and industrial | Paycheck Protection Program ("PPP") | Impact of ASU 2016-13 adoption on January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	0
Balance at end of year		0
Commercial and industrial | Paycheck Protection Program ("PPP") | Adjusted balance at January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	0
Purchased Credit Deteriorated Allowance	0
Loans charged-off	0	0
Recoveries	0	0
Provision	0	0
Balance at end of year		0
Commercial and industrial | Owner occupied commercial real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	7,921	6,247
Balance at end of year	20,001	7,921	6,247
Commercial and industrial | Owner occupied commercial real estate | Impact of ASU 2016-13 adoption on January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	(114)
Balance at end of year		(114)
Commercial and industrial | Owner occupied commercial real estate | Adjusted balance at January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	7,807
Purchased Credit Deteriorated Allowance	1,205
Loans charged-off	(13,671)	(119)
Recoveries	205	178
Provision	24,455	1,615
Balance at end of year		7,807
Commercial and industrial | Non-owner occupied commercial real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	7,584	7,182
Balance at end of year	20,873	7,584	7,182
Commercial and industrial | Non-owner occupied commercial real estate | Impact of ASU 2016-13 adoption on January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	(2,617)
Balance at end of year		(2,617)
Commercial and industrial | Non-owner occupied commercial real estate | Adjusted balance at January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	4,967
Purchased Credit Deteriorated Allowance	6,465
Loans charged-off	(45)	(21)
Recoveries	30	201
Provision	9,456	222
Balance at end of year		4,967
Commercial and industrial | Real estate construction
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	8,677	6,707
Balance at end of year	20,080	8,677	6,707
Commercial and industrial | Real estate construction | Impact of ASU 2016-13 adoption on January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	6,335
Balance at end of year		6,335
Commercial and industrial | Real estate construction | Adjusted balance at January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	15,012
Purchased Credit Deteriorated Allowance	603
Loans charged-off	(105)	(156)
Recoveries	220	255
Provision	4,350	1,871
Balance at end of year		15,012
Agricultural and agricultural real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	5,680	4,916
Balance at end of year	7,129	5,680	4,916
Agricultural and agricultural real estate | Impact of ASU 2016-13 adoption on January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	(387)
Balance at end of year		(387)
Agricultural and agricultural real estate | Adjusted balance at January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	5,293
Purchased Credit Deteriorated Allowance	1,848
Loans charged-off	(1,201)	(2,633)
Recoveries	971	529
Provision	218	2,868
Balance at end of year		5,293
Residential real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	1,504	1,813
Balance at end of year	11,935	1,504	1,813
Residential real estate | Impact of ASU 2016-13 adoption on January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	4,817
Balance at end of year		4,817
Residential real estate | Adjusted balance at January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	6,321
Purchased Credit Deteriorated Allowance	410
Loans charged-off	(515)	(458)
Recoveries	108	139
Provision	5,611	10
Balance at end of year		6,321
Consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	4,822	5,140
Balance at end of year	12,770	4,822	$ 5,140
Consumer | Impact of ASU 2016-13 adoption on January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	4,309
Balance at end of year		4,309
Consumer | Adjusted balance at January 1, 2020
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	9,131
Purchased Credit Deteriorated Allowance	75
Loans charged-off	(2,211)	(3,074)
Recoveries	993	1,601
Provision	$ 4,782	1,155
Balance at end of year		$ 9,131