LOANS (Allowance for credit losses on financing receivables) (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans individually evaluated for impairment, nonaccrual threshold	$ 500,000
Allowance For Credit Losses
Individually Evaluated for Credit Losses	23,090,000	$ 20,413,000
Collectively Evaluated for Credit Losses	100,844,000	102,153,000
Total	123,934,000	122,566,000	$ 112,707,000	$ 109,483,000
Gross Loans Receivable Held to Maturity
Loans Individually Evaluated for Credit Losses	81,503,000	80,385,000
Loans Collectively Evaluated for Credit Losses	11,563,138,000	11,988,260,000
Total	11,644,641,000	12,068,645,000
Paycheck Protection Program ("PPP")
Allowance For Credit Losses
Total	0
Commercial and industrial | Commercial and industrial
Allowance For Credit Losses
Individually Evaluated for Credit Losses	20,555,000	18,425,000
Collectively Evaluated for Credit Losses	20,550,000	22,254,000
Total	41,105,000	40,679,000	31,823,000	29,071,000
Gross Loans Receivable Held to Maturity
Loans Individually Evaluated for Credit Losses	42,847,000	41,847,000
Loans Collectively Evaluated for Credit Losses	3,502,204,000	3,610,200,000
Total	3,545,051,000	3,652,047,000
Commercial and industrial | Paycheck Protection Program ("PPP")
Allowance For Credit Losses
Individually Evaluated for Credit Losses	0	0
Collectively Evaluated for Credit Losses	0	0
Total	0	0
Gross Loans Receivable Held to Maturity
Loans Individually Evaluated for Credit Losses	0	0
Loans Collectively Evaluated for Credit Losses	2,172,000	2,777,000
Total	2,172,000	2,777,000
Commercial and industrial | Owner occupied commercial real estate
Allowance For Credit Losses
Individually Evaluated for Credit Losses	0	0
Collectively Evaluated for Credit Losses	14,395,000	17,156,000
Total	14,395,000	17,156,000	14,151,000	13,948,000
Gross Loans Receivable Held to Maturity
Loans Individually Evaluated for Credit Losses	30,089,000	30,400,000
Loans Collectively Evaluated for Credit Losses	2,514,944,000	2,607,775,000
Total	2,545,033,000	2,638,175,000
Commercial and industrial | Non-owner occupied commercial real estate
Allowance For Credit Losses
Individually Evaluated for Credit Losses	0	0
Collectively Evaluated for Credit Losses	15,770,000	17,249,000
Total	15,770,000	17,249,000	17,062,000	16,539,000
Gross Loans Receivable Held to Maturity
Loans Individually Evaluated for Credit Losses	0	0
Loans Collectively Evaluated for Credit Losses	2,495,068,000	2,553,711,000
Total	2,495,068,000	2,553,711,000
Commercial and industrial | Real estate construction
Allowance For Credit Losses
Individually Evaluated for Credit Losses	56,000	56,000
Collectively Evaluated for Credit Losses	34,869,000	28,717,000
Total	34,925,000	28,773,000	30,138,000	29,998,000
Gross Loans Receivable Held to Maturity
Loans Individually Evaluated for Credit Losses	697,000	697,000
Loans Collectively Evaluated for Credit Losses	1,040,886,000	1,011,019,000
Total	1,041,583,000	1,011,716,000
Agricultural and agricultural real estate
Allowance For Credit Losses
Individually Evaluated for Credit Losses	2,479,000	1,932,000
Collectively Evaluated for Credit Losses	2,629,000	2,360,000
Total	5,108,000	4,292,000	2,546,000	2,634,000
Gross Loans Receivable Held to Maturity
Loans Individually Evaluated for Credit Losses	7,143,000	6,700,000
Loans Collectively Evaluated for Credit Losses	802,733,000	912,484,000
Total	809,876,000	919,184,000
Residential real estate
Allowance For Credit Losses
Individually Evaluated for Credit Losses	0	0
Collectively Evaluated for Credit Losses	5,155,000	5,845,000
Total	5,155,000	5,845,000	7,564,000	7,711,000
Gross Loans Receivable Held to Maturity
Loans Individually Evaluated for Credit Losses	727,000	741,000
Loans Collectively Evaluated for Credit Losses	755,294,000	797,088,000
Total	756,021,000	797,829,000
Consumer
Allowance For Credit Losses
Individually Evaluated for Credit Losses	0	0
Collectively Evaluated for Credit Losses	7,476,000	8,572,000
Total	7,476,000	8,572,000	$ 9,423,000	$ 9,582,000
Gross Loans Receivable Held to Maturity
Loans Individually Evaluated for Credit Losses	0	0
Loans Collectively Evaluated for Credit Losses	449,837,000	493,206,000
Total	$ 449,837,000	$ 493,206,000