FAIR VALUE (Estimated fair value financial instruments incl. carrying amounts) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Securities:
Held to maturity	$ 86,486	$ 94,139
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets:
Cash and cash equivalents	604,902	435,599
Time deposits in other financial institutions	2,894	2,894
Securities:
Carried at fair value	1,001	1,008
Held to maturity	0	0
Other investments	0	0
Loans held for sale	0	0
Loans, net	0	0
Cash surrender value on life insurance	0	0
Derivative instruments	0	0
Financial liabilities:
Short term borrowings	0	0
Other borrowings	0	0
Derivative liabilities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate lock commitments
Securities:
Derivative instruments	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Demand deposits
Financial liabilities:
Deposits	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Savings deposits
Financial liabilities:
Deposits	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Time deposits
Financial liabilities:
Deposits	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Forward commitments
Securities:
Derivative instruments	0	0
Financial liabilities:
Derivative liabilities	0	0
Level 2
Financial assets:
Cash and cash equivalents	0	0
Time deposits in other financial institutions	0	0
Securities:
Carried at fair value	7,024,242	7,529,366
Held to maturity	86,486	94,139
Other investments	82,751	82,567
Loans held for sale	22,685	21,640
Loans, net	9,990,082	9,809,915
Cash surrender value on life insurance	192,267	191,722
Derivative instruments	11,657	23,891
Financial liabilities:
Short term borrowings	107,372	131,597
Other borrowings	373,288	373,194
Derivative liabilities	11,682	25,099
Level 2 | Interest rate lock commitments
Securities:
Derivative instruments	0	0
Level 2 | Demand deposits
Financial liabilities:
Deposits	6,376,249	6,495,326
Level 2 | Savings deposits
Financial liabilities:
Deposits	9,236,427	8,897,909
Level 2 | Time deposits
Financial liabilities:
Deposits	1,054,008	1,024,020
Level 2 | Forward commitments
Securities:
Derivative instruments	1,008	32
Financial liabilities:
Derivative liabilities	35	95
Significant Unobservable Inputs (Level 3)
Financial assets:
Cash and cash equivalents	0	0
Time deposits in other financial institutions	0	0
Securities:
Carried at fair value	0	0
Held to maturity	0	0
Other investments	0	0
Loans held for sale	0	0
Loans, net	43,893	41,641
Cash surrender value on life insurance	0	0
Derivative instruments	0	0
Financial liabilities:
Short term borrowings	0	0
Other borrowings	0	0
Derivative liabilities	0	0
Significant Unobservable Inputs (Level 3) | Interest rate lock commitments
Securities:
Derivative instruments	696	1,306
Significant Unobservable Inputs (Level 3) | Demand deposits
Financial liabilities:
Deposits	0	0
Significant Unobservable Inputs (Level 3) | Savings deposits
Financial liabilities:
Deposits	0	0
Significant Unobservable Inputs (Level 3) | Time deposits
Financial liabilities:
Deposits	0	0
Significant Unobservable Inputs (Level 3) | Forward commitments
Securities:
Derivative instruments	0	0
Financial liabilities:
Derivative liabilities	0	0
Commercial and industrial | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial and industrial
Securities:
Loans, net	0	0
Commercial and industrial | Quoted Prices in Active Markets for Identical Assets (Level 1) | Paycheck Protection Program ("PPP")
Securities:
Loans, net	0	0
Commercial and industrial | Quoted Prices in Active Markets for Identical Assets (Level 1) | Owner occupied commercial real estate
Securities:
Loans, net	0	0
Commercial and industrial | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-owner occupied commercial real estate
Securities:
Loans, net	0	0
Commercial and industrial | Quoted Prices in Active Markets for Identical Assets (Level 1) | Real estate construction
Securities:
Loans, net	0	0
Commercial and industrial | Level 2 | Commercial and industrial
Securities:
Loans, net	2,749,557	2,594,012
Commercial and industrial | Level 2 | Paycheck Protection Program ("PPP")
Securities:
Loans, net	74,065	199,883
Commercial and industrial | Level 2 | Owner occupied commercial real estate
Securities:
Loans, net	2,227,237	2,213,583
Commercial and industrial | Level 2 | Non-owner occupied commercial real estate
Securities:
Loans, net	2,126,690	1,986,215
Commercial and industrial | Level 2 | Real estate construction
Securities:
Loans, net	827,481	844,578
Commercial and industrial | Significant Unobservable Inputs (Level 3) | Commercial and industrial
Securities:
Loans, net	10,547	8,989
Commercial and industrial | Significant Unobservable Inputs (Level 3) | Paycheck Protection Program ("PPP")
Securities:
Loans, net	0	0
Commercial and industrial | Significant Unobservable Inputs (Level 3) | Owner occupied commercial real estate
Securities:
Loans, net	9,247	8,447
Commercial and industrial | Significant Unobservable Inputs (Level 3) | Non-owner occupied commercial real estate
Securities:
Loans, net	11,738	11,946
Commercial and industrial | Significant Unobservable Inputs (Level 3) | Real estate construction
Securities:
Loans, net	1,984	0
Agricultural and agricultural real estate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Securities:
Loans, net	0	0
Agricultural and agricultural real estate | Level 2
Securities:
Loans, net	747,072	737,834
Agricultural and agricultural real estate | Significant Unobservable Inputs (Level 3)
Securities:
Loans, net	9,514	11,404
Residential real estate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Securities:
Loans, net	0	0
Residential real estate | Level 2
Securities:
Loans, net	816,899	818,323
Residential real estate | Significant Unobservable Inputs (Level 3)
Securities:
Loans, net	863	855
Consumer | Quoted Prices in Active Markets for Identical Assets (Level 1)
Securities:
Loans, net	0	0
Consumer | Level 2
Securities:
Loans, net	421,081	415,487
Consumer | Significant Unobservable Inputs (Level 3)
Securities:
Loans, net	0	0
Carrying Amount
Financial assets:
Cash and cash equivalents	604,902	435,599
Time deposits in other financial institutions	2,894	2,894
Securities:
Carried at fair value	7,025,243	7,530,374
Held to maturity	81,785	84,709
Other investments	82,751	82,567
Loans held for sale	22,685	21,640
Loans, net	10,076,863	9,844,484
Cash surrender value on life insurance	192,267	191,722
Derivative instruments	11,657	23,891
Financial liabilities:
Short term borrowings	107,372	131,597
Other borrowings	372,290	372,072
Derivative liabilities	11,682	25,099
Carrying Amount | Interest rate lock commitments
Securities:
Derivative instruments	696	1,306
Carrying Amount | Demand deposits
Financial liabilities:
Deposits	6,376,249	6,495,326
Carrying Amount | Savings deposits
Financial liabilities:
Deposits	9,236,427	8,897,909
Carrying Amount | Time deposits
Financial liabilities:
Deposits	1,054,008	1,024,020
Carrying Amount | Forward commitments
Securities:
Derivative instruments	1,008	32
Financial liabilities:
Derivative liabilities	35	95
Carrying Amount | Commercial and industrial | Commercial and industrial
Securities:
Loans, net	2,788,713	2,617,347
Carrying Amount | Commercial and industrial | Paycheck Protection Program ("PPP")
Securities:
Loans, net	74,065	199,883
Carrying Amount | Commercial and industrial | Owner occupied commercial real estate
Securities:
Loans, net	2,248,101	2,221,120
Carrying Amount | Commercial and industrial | Non-owner occupied commercial real estate
Securities:
Loans, net	2,145,748	1,992,683
Carrying Amount | Commercial and industrial | Real estate construction
Securities:
Loans, net	821,086	833,581
Carrying Amount | Agricultural and agricultural real estate
Securities:
Loans, net	763,776	748,540
Carrying Amount | Residential real estate
Securities:
Loans, net	817,367	820,856
Carrying Amount | Consumer
Securities:
Loans, net	418,007	410,474
Estimated Fair Value
Financial assets:
Cash and cash equivalents	604,902	435,599
Time deposits in other financial institutions	2,894	2,894
Securities:
Carried at fair value	7,025,243	7,530,374
Held to maturity	86,486	94,139
Other investments	82,751	82,567
Loans held for sale	22,685	21,640
Loans, net	10,033,975	9,851,556
Cash surrender value on life insurance	192,267	191,722
Derivative instruments	11,657	23,891
Financial liabilities:
Short term borrowings	107,372	131,597
Other borrowings	373,288	373,194
Derivative liabilities	11,682	25,099
Estimated Fair Value | Interest rate lock commitments
Securities:
Derivative instruments	696	1,306
Estimated Fair Value | Demand deposits
Financial liabilities:
Deposits	6,376,249	6,495,326
Estimated Fair Value | Savings deposits
Financial liabilities:
Deposits	9,236,427	8,897,909
Estimated Fair Value | Time deposits
Financial liabilities:
Deposits	1,054,008	1,024,020
Estimated Fair Value | Forward commitments
Securities:
Derivative instruments	1,008	32
Financial liabilities:
Derivative liabilities	35	95
Estimated Fair Value | Commercial and industrial | Commercial and industrial
Securities:
Loans, net	2,760,104	2,603,001
Estimated Fair Value | Commercial and industrial | Paycheck Protection Program ("PPP")
Securities:
Loans, net	74,065	199,883
Estimated Fair Value | Commercial and industrial | Owner occupied commercial real estate
Securities:
Loans, net	2,236,484	2,222,030
Estimated Fair Value | Commercial and industrial | Non-owner occupied commercial real estate
Securities:
Loans, net	2,138,428	1,998,161
Estimated Fair Value | Commercial and industrial | Real estate construction
Securities:
Loans, net	829,465	844,578
Estimated Fair Value | Agricultural and agricultural real estate
Securities:
Loans, net	756,586	749,238
Estimated Fair Value | Residential real estate
Securities:
Loans, net	817,762	819,178
Estimated Fair Value | Consumer
Securities:
Loans, net	$ 421,081	$ 415,487