FAIR VALUE (Estimated fair value financial instruments incl. carrying amounts) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Securities:
Carried at fair value	$ 873,218
Held to maturity	842,980	$ 838,241
Deposits held for sale	538,308	0
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets:
Cash and cash equivalents	373,946	323,013
Time deposits in other financial institutions	1,340	1,240
Securities:
Carried at fair value	15,847	32,118
Held to maturity	0	0
Other investments	0	0
Loans held for sale	0	0
Loans, net	0	0
Deposits held for sale	0
Cash surrender value on life insurance	0	0
Derivative financial instrument	0	0
Financial liabilities:
Borrowings	0	0
Term Debt	0	0
Derivative financial instrument	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
Significant Other Observable Inputs (Level 2)
Financial assets:
Cash and cash equivalents	0	0
Time deposits in other financial institutions	0	0
Securities:
Carried at fair value	4,169,207	4,614,773
Held to maturity	809,516	816,399
Other investments	70,684	91,277
Loans held for sale	348,761	5,071
Loans, net	10,763,157	11,149,694
Deposits held for sale	569,298
Cash surrender value on life insurance	199,036	197,085
Derivative financial instrument	128,849	84,904
Financial liabilities:
Borrowings	694,909	622,255
Term Debt	374,830	374,017
Derivative financial instrument	64,905	84,249
Significant Other Observable Inputs (Level 2) | Demand deposits
Financial liabilities:
Deposits	4,244,169	4,500,304
Significant Other Observable Inputs (Level 2) | Savings deposits
Financial liabilities:
Deposits	8,470,416	8,805,597
Significant Other Observable Inputs (Level 2) | Time deposits
Financial liabilities:
Deposits	2,242,005	2,895,813
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	58,630	59,973
Deposits held for sale	0
Cash surrender value on life insurance	0	0
Derivative financial instrument	0	0
Financial liabilities:
Borrowings	0	0
Term Debt	0	0
Derivative financial instrument	0	0
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
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 | Significant Other Observable Inputs (Level 2) | Commercial and industrial
Securities:
Loans, net	3,285,535	3,373,206
Commercial and industrial | Significant Other Observable Inputs (Level 2) | Paycheck Protection Program ("PPP")
Securities:
Loans, net	1,864	2,777
Commercial and industrial | Significant Other Observable Inputs (Level 2) | Owner occupied commercial real estate
Securities:
Loans, net	2,362,693	2,414,140
Commercial and industrial | Significant Other Observable Inputs (Level 2) | Non-owner occupied commercial real estate
Securities:
Loans, net	2,297,208	2,393,931
Commercial and industrial | Significant Other Observable Inputs (Level 2) | Real estate construction
Securities:
Loans, net	1,042,588	978,463
Commercial and industrial | Significant Unobservable Inputs (Level 3) | Commercial and industrial
Securities:
Loans, net	19,938	23,422
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	12,579	30,400
Commercial and industrial | Significant Unobservable Inputs (Level 3) | Non-owner occupied commercial real estate
Securities:
Loans, net	0	0
Commercial and industrial | Significant Unobservable Inputs (Level 3) | Real estate construction
Securities:
Loans, net	675	642
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 | Significant Other Observable Inputs (Level 2)
Securities:
Loans, net	706,242	834,804
Agricultural and agricultural real estate | Significant Unobservable Inputs (Level 3)
Securities:
Loans, net	24,711	4,768
Residential real estate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Securities:
Loans, net	0	0
Residential real estate | Significant Other Observable Inputs (Level 2)
Securities:
Loans, net	636,118	686,687
Residential real estate | Significant Unobservable Inputs (Level 3)
Securities:
Loans, net	727	741
Consumer | Quoted Prices in Active Markets for Identical Assets (Level 1)
Securities:
Loans, net	0	0
Consumer | Significant Other Observable Inputs (Level 2)
Securities:
Loans, net	430,909	465,686
Consumer | Significant Unobservable Inputs (Level 3)
Securities:
Loans, net	0	0
Carrying Amount
Financial assets:
Cash and cash equivalents	373,946	323,013
Time deposits in other financial institutions	1,340	1,240
Securities:
Carried at fair value	4,185,054	4,646,891
Held to maturity	842,980	838,241
Other investments	70,684	91,277
Loans held for sale	348,761	5,071
Loans, net	11,481,448	11,946,079
Deposits held for sale	538,308
Cash surrender value on life insurance	199,036	197,085
Derivative financial instrument	128,849	84,904
Financial liabilities:
Borrowings	694,909	622,255
Term Debt	372,988	372,396
Derivative financial instrument	64,905	84,249
Carrying Amount | Demand deposits
Financial liabilities:
Deposits	4,244,169	4,500,304
Carrying Amount | Savings deposits
Financial liabilities:
Deposits	8,470,416	8,805,597
Carrying Amount | Time deposits
Financial liabilities:
Deposits	2,242,005	2,895,813
Carrying Amount | Commercial and industrial | Commercial and industrial
Securities:
Loans, net	3,496,439	3,611,368
Carrying Amount | Commercial and industrial | Paycheck Protection Program ("PPP")
Securities:
Loans, net	1,864	2,777
Carrying Amount | Commercial and industrial | Owner occupied commercial real estate
Securities:
Loans, net	2,541,250	2,621,019
Carrying Amount | Commercial and industrial | Non-owner occupied commercial real estate
Securities:
Loans, net	2,420,561	2,536,462
Carrying Amount | Commercial and industrial | Real estate construction
Securities:
Loans, net	1,050,516	982,943
Carrying Amount | Agricultural and agricultural real estate
Securities:
Loans, net	794,053	914,892
Carrying Amount | Residential real estate
Securities:
Loans, net	728,365	791,984
Carrying Amount | Consumer
Securities:
Loans, net	448,400	484,634
Estimated Fair Value
Financial assets:
Cash and cash equivalents	373,946	323,013
Time deposits in other financial institutions	1,340	1,240
Securities:
Carried at fair value	4,185,054	4,646,891
Held to maturity	809,516	816,399
Other investments	70,684	91,277
Loans held for sale	348,761	5,071
Loans, net	10,821,787	11,209,667
Deposits held for sale	569,298
Cash surrender value on life insurance	199,036	197,085
Derivative financial instrument	128,849	84,904
Financial liabilities:
Borrowings	694,909	622,255
Term Debt	374,830	374,017
Derivative financial instrument	64,905	84,249
Estimated Fair Value | Demand deposits
Financial liabilities:
Deposits	4,244,169	4,500,304
Estimated Fair Value | Savings deposits
Financial liabilities:
Deposits	8,470,416	8,805,597
Estimated Fair Value | Time deposits
Financial liabilities:
Deposits	2,242,005	2,895,813
Estimated Fair Value | Commercial and industrial | Commercial and industrial
Securities:
Loans, net	3,305,473	3,396,628
Estimated Fair Value | Commercial and industrial | Paycheck Protection Program ("PPP")
Securities:
Loans, net	1,864	2,777
Estimated Fair Value | Commercial and industrial | Owner occupied commercial real estate
Securities:
Loans, net	2,375,272	2,444,540
Estimated Fair Value | Commercial and industrial | Non-owner occupied commercial real estate
Securities:
Loans, net	2,297,208	2,393,931
Estimated Fair Value | Commercial and industrial | Real estate construction
Securities:
Loans, net	1,043,263	979,105
Estimated Fair Value | Agricultural and agricultural real estate
Securities:
Loans, net	730,953	839,572
Estimated Fair Value | Residential real estate
Securities:
Loans, net	636,845	687,428
Estimated Fair Value | Consumer
Securities:
Loans, net	$ 430,909	$ 465,686