FAIR VALUE (Estimated fair value financial instruments incl. carrying amounts) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Securities:
Carried at fair value	$ 1,733,121
Held to maturity	10,678,218	$ 9,954,572
Total	81,939	84,709
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets:
Cash and cash equivalents	384,794	435,599
Time deposits in other financial institutions	1,855	2,894
Securities:
Carried at fair value	13,890	1,008
Held to maturity		0
Other investments	0	0
Total	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	7,092,328	7,529,366
Held to maturity		94,139
Other investments	85,899	82,567
Total	85,212
Loans held for sale	18,803	21,640
Loans, net	10,293,018	9,809,915
Cash surrender value on life insurance	192,474	191,722
Derivative instruments	19,054	23,891
Financial liabilities:
Short term borrowings	97,749	131,597
Other borrowings	373,465	373,194
Derivative liabilities	19,037	25,099
Level 2 \| Interest rate lock commitments
Securities:
Derivative instruments	0	0
Level 2 \| Demand deposits
Financial liabilities:
Deposits	6,087,304	6,495,326
Level 2 \| Savings deposits
Financial liabilities:
Deposits	10,059,678	8,897,909
Level 2 \| Time deposits
Financial liabilities:
Deposits	1,078,568	1,024,020
Level 2 \| Forward commitments
Securities:
Derivative instruments	201	32
Financial liabilities:
Derivative liabilities	196	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
Other investments	0	0
Total	0
Loans held for sale	0	0
Loans, net	44,986	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	955	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 \| Commercial and industrial
Securities:
Held to maturity	3,059,519	2,645,085
Commercial and industrial \| Paycheck Protection Program ("PPP")
Securities:
Held to maturity	23,031	199,883
Commercial and industrial \| Owner occupied commercial real estate
Securities:
Held to maturity	2,282,833	2,240,334
Commercial and industrial \| Non-owner occupied commercial real estate
Securities:
Held to maturity	2,321,718	2,010,591
Commercial and industrial \| Real estate construction
Securities:
Held to maturity	845,045	856,119
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	2,941,788	2,594,012
Commercial and industrial \| Level 2 \| Paycheck Protection Program ("PPP")
Securities:
Loans, net	23,031	199,883
Commercial and industrial \| Level 2 \| Owner occupied commercial real estate
Securities:
Loans, net	2,192,853	2,213,583
Commercial and industrial \| Level 2 \| Non-owner occupied commercial real estate
Securities:
Loans, net	2,241,734	1,986,215
Commercial and industrial \| Level 2 \| Real estate construction
Securities:
Loans, net	826,234	844,578
Commercial and industrial \| Significant Unobservable Inputs (Level 3) \| Commercial and industrial
Securities:
Loans, net	12,545	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	10,885	8,447
Commercial and industrial \| Significant Unobservable Inputs (Level 3) \| Non-owner occupied commercial real estate
Securities:
Loans, net	11,959	11,946
Commercial and industrial \| Significant Unobservable Inputs (Level 3) \| Real estate construction
Securities:
Loans, net	1,575	0
Agricultural and agricultural real estate
Securities:
Held to maturity	836,703	753,753
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	793,807	737,834
Agricultural and agricultural real estate \| Significant Unobservable Inputs (Level 3)
Securities:
Loans, net	7,177	11,404
Residential real estate
Securities:
Held to maturity	845,270	829,283
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	819,735	818,323
Residential real estate \| Significant Unobservable Inputs (Level 3)
Securities:
Loans, net	845	855
Consumer
Securities:
Held to maturity	464,099	419,524
Consumer \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Securities:
Loans, net	0	0
Consumer \| Level 2
Securities:
Loans, net	453,836	415,487
Consumer \| Significant Unobservable Inputs (Level 3)
Securities:
Loans, net	0	0
Carrying Amount
Financial assets:
Cash and cash equivalents	384,794	435,599
Time deposits in other financial institutions	1,855	2,894
Securities:
Carried at fair value	7,106,218	7,530,374
Held to maturity		84,709
Other investments	85,899	82,567
Total	81,939
Loans held for sale	18,803	21,640
Loans, net	10,678,218	9,844,484
Cash surrender value on life insurance	192,474	191,722
Derivative instruments	19,054	23,891
Financial liabilities:
Short term borrowings	97,749	131,597
Other borrowings	372,538	372,072
Derivative liabilities	19,037	25,099
Carrying Amount \| Interest rate lock commitments
Securities:
Derivative instruments	955	1,306
Carrying Amount \| Demand deposits
Financial liabilities:
Deposits	6,087,304	6,495,326
Carrying Amount \| Savings deposits
Financial liabilities:
Deposits	10,059,678	8,897,909
Carrying Amount \| Time deposits
Financial liabilities:
Deposits	1,078,568	1,024,020
Carrying Amount \| Forward commitments
Securities:
Derivative instruments	201	32
Financial liabilities:
Derivative liabilities	196	95
Carrying Amount \| Commercial and industrial \| Commercial and industrial
Securities:
Loans, net	3,059,519	2,617,347
Carrying Amount \| Commercial and industrial \| Paycheck Protection Program ("PPP")
Securities:
Loans, net	23,031	199,883
Carrying Amount \| Commercial and industrial \| Owner occupied commercial real estate
Securities:
Loans, net	2,282,833	2,221,120
Carrying Amount \| Commercial and industrial \| Non-owner occupied commercial real estate
Securities:
Loans, net	2,321,718	1,992,683
Carrying Amount \| Commercial and industrial \| Real estate construction
Securities:
Loans, net	845,045	833,581
Carrying Amount \| Agricultural and agricultural real estate
Securities:
Loans, net	836,703	748,540
Carrying Amount \| Residential real estate
Securities:
Loans, net	845,270	820,856
Carrying Amount \| Consumer
Securities:
Loans, net	464,099	410,474
Estimated Fair Value
Financial assets:
Cash and cash equivalents	384,794	435,599
Time deposits in other financial institutions	1,855	2,894
Securities:
Carried at fair value	7,106,218	7,530,374
Held to maturity		94,139
Other investments	85,899	82,567
Total	85,212
Loans held for sale	18,803	21,640
Loans, net	10,338,004	9,851,556
Cash surrender value on life insurance	192,474	191,722
Derivative instruments	19,054	23,891
Financial liabilities:
Short term borrowings	97,749	131,597
Other borrowings	373,465	373,194
Derivative liabilities	19,037	25,099
Estimated Fair Value \| Interest rate lock commitments
Securities:
Derivative instruments	955	1,306
Estimated Fair Value \| Demand deposits
Financial liabilities:
Deposits	6,087,304	6,495,326
Estimated Fair Value \| Savings deposits
Financial liabilities:
Deposits	10,059,678	8,897,909
Estimated Fair Value \| Time deposits
Financial liabilities:
Deposits	1,078,568	1,024,020
Estimated Fair Value \| Forward commitments
Securities:
Derivative instruments	201	32
Financial liabilities:
Derivative liabilities	196	95
Estimated Fair Value \| Commercial and industrial \| Commercial and industrial
Securities:
Loans, net	2,954,333	2,603,001
Estimated Fair Value \| Commercial and industrial \| Paycheck Protection Program ("PPP")
Securities:
Loans, net	23,031	199,883
Estimated Fair Value \| Commercial and industrial \| Owner occupied commercial real estate
Securities:
Loans, net	2,203,738	2,222,030
Estimated Fair Value \| Commercial and industrial \| Non-owner occupied commercial real estate
Securities:
Loans, net	2,253,693	1,998,161
Estimated Fair Value \| Commercial and industrial \| Real estate construction
Securities:
Loans, net	827,809	844,578
Estimated Fair Value \| Agricultural and agricultural real estate
Securities:
Loans, net	800,984	749,238
Estimated Fair Value \| Residential real estate
Securities:
Loans, net	820,580	819,178
Estimated Fair Value \| Consumer
Securities:
Loans, net	$ 453,836	$ 415,487

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