LOANS AND ALLOWANCE FOR CREDIT LOSSES - Past due (Details) - USD ($)	Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024
Financing Receivable, Allowance for Credit Loss [Line Items]
Current - 29 Days Past Due	$ 938,471,000	$ 936,997,000
Total	957,012,000	946,826,000	$ 934,599,000
90 Days or Greater Past Due and Still Accruing Interest	2,415,000	756,000
Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	4,532,000	4,636,000
Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	7,429,000	223,000
Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	6,580,000	4,970,000
Financial Asset, Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	18,541,000	9,829,000
Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Current - 29 Days Past Due	847,708,000	841,218,000
Total	866,145,000	850,656,000	836,213,000
90 Days or Greater Past Due and Still Accruing Interest	2,415,000	756,000
Real Estate | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	4,428,000	4,247,000
Real Estate | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	7,429,000	221,000
Real Estate | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	6,580,000	4,970,000
Real Estate | Financial Asset, Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	18,437,000	9,438,000
Agricultural
Financing Receivable, Allowance for Credit Loss [Line Items]
Current - 29 Days Past Due	1,071,000	936,000
Total	1,071,000	936,000	1,008,000
Commercial and Industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Current - 29 Days Past Due	63,890,000	66,328,000
Total	63,988,000	66,706,000	66,804,000
Commercial and Industrial | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	98,000	378,000
Commercial and Industrial | Financial Asset, Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	98,000	378,000
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Current - 29 Days Past Due	5,440,000	6,377,000
Total	5,446,000	6,390,000	6,166,000
Consumer | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	6,000	11,000
Consumer | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total		2,000
Consumer | Financial Asset, Past Due
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	6,000	13,000
State and Political Subdivisions
Financing Receivable, Allowance for Credit Loss [Line Items]
Current - 29 Days Past Due	20,362,000	22,138,000
Total	$ 20,362,000	$ 22,138,000	$ 24,408,000