LOANS AND ALLOWANCE FOR CREDIT LOSSES - Additional Information (Details)	3 Months Ended								9 Months Ended								12 Months Ended
	Sep. 30, 2025 USD ($) contract	Sep. 30, 2025 USD ($)	Sep. 30, 2025 USD ($) loan	Sep. 30, 2024 USD ($)	Sep. 30, 2024 USD ($) contract	Sep. 30, 2024 USD ($)	Sep. 30, 2024 USD ($) loan	Mar. 31, 2024 USD ($) contract	Sep. 30, 2025 USD ($)	Sep. 30, 2025 USD ($) contract	Sep. 30, 2025 USD ($)	Sep. 30, 2025 USD ($) loan	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($) contract	Sep. 30, 2024 USD ($)	Sep. 30, 2024 USD ($) loan	Dec. 31, 2024 USD ($) loan
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans Receivable Held-for-sale, Amount	$ 103,000	$ 103,000	$ 103,000						$ 103,000	$ 103,000	$ 103,000	$ 103,000	$ 103,000				$ 737,000
Unpaid principal balance	957,012,000	957,012,000	957,012,000	$ 934,599,000	$ 934,599,000	$ 934,599,000	$ 934,599,000		$ 957,012,000	957,012,000	957,012,000	957,012,000	957,012,000	$ 934,599,000	$ 934,599,000	$ 934,599,000	946,826,000
Loan payments of delinquency period									10 days
Delinquency notice is automatically generated									10 or 15
Loan Payments, Delinquency Period, Beyond Which Loans are Considered Non-Accrual									90 days
Reserve for unfunded lending commitments	90,000	90,000	90,000	173,000	$ 173,000	173,000	$ 173,000		$ 90,000	90,000	90,000	90,000	90,000	$ 173,000	173,000	$ 173,000
Accrued interest exclude from the amortized cost basis of loans	$ 2,638,000	2,638,000	$ 2,638,000						$ 2,638,000	$ 2,638,000	2,638,000	$ 2,638,000	2,638,000				$ 2,575,000
Number of contracts	1		1		1		1	1		1		1		2		2	0
Modified value of TDR		107,000				120,000		$ 9,455,000			107,000				9,575,000
Period of interest only payments									11 months
Recorded Investment		107,000				120,000					107,000				9,547,000		$ 10,193,000
Financing receivable modifications unfunded commitments											0						0
Financing Receivable, Modifications, Recorded Investment	$ 107,000	107,000	$ 107,000						$ 107,000	$ 107,000	107,000	$ 107,000	107,000				10,193,000
Loan carrying a post modification recorded investment, paid current	421,000	421,000	$ 421,000	$ 9,427,000	$ 9,427,000	9,427,000	$ 9,427,000		421,000	421,000	421,000	$ 421,000	421,000	$ 9,427,000	$ 9,427,000	$ 9,427,000
Number of loans modified as troubled debt restructuring within previous 12 months, with subsequent payment default			0									2			1
Number of financing receivable contracts modified | loan			1									1
Foreclosed Assets Held For Resale	0	0	$ 0						0	0	0	$ 0	0				0
Consumer mortgage loans	0	0	0						0	0	0	0	0				0
GGLs
Financing Receivable, Allowance for Credit Loss [Line Items]
Unpaid principal balance	3,939,000	3,939,000	3,939,000						3,939,000	3,939,000	3,939,000	3,939,000	3,939,000				4,306,000
Unfunded Loan Commitment
Financing Receivable, Allowance for Credit Loss [Line Items]
Reserve for unfunded lending commitments	90,000	90,000	$ 90,000						90,000	90,000	90,000	$ 90,000	90,000				102,000
Term Modification
Financing Receivable, Allowance for Credit Loss [Line Items]
Number of contracts | loan							1									1
Period of maturity date extension				10 months
Payment Modification
Financing Receivable, Allowance for Credit Loss [Line Items]
Number of contracts | loan			1									1				1
Commercial and Industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Unpaid principal balance	63,988,000	63,988,000	$ 63,988,000	$ 66,804,000	66,804,000	66,804,000	$ 66,804,000		63,988,000	63,988,000	63,988,000	$ 63,988,000	63,988,000	66,804,000	$ 66,804,000	$ 66,804,000	66,706,000
Reserve for unfunded lending commitments	27,000	27,000	27,000	23,000	23,000	23,000	23,000		27,000	27,000	27,000	27,000	27,000	23,000	23,000	23,000
Financing Receivable, Modifications, Recorded Investment																	174,000
Commercial and Industrial | GGLs
Financing Receivable, Allowance for Credit Loss [Line Items]
Government Guaranteed Loans.	3,939,000	3,939,000	3,939,000						3,939,000	3,939,000	3,939,000	3,939,000	3,939,000				4,306,000
Commercial and Industrial | Unfunded Loan Commitment
Financing Receivable, Allowance for Credit Loss [Line Items]
Reserve for unfunded lending commitments																	17,000
State and Political Subdivisions
Financing Receivable, Allowance for Credit Loss [Line Items]
Unpaid principal balance	20,362,000	20,362,000	20,362,000	24,408,000	24,408,000	24,408,000	24,408,000		20,362,000	20,362,000	20,362,000	20,362,000	20,362,000	24,408,000	24,408,000	24,408,000	22,138,000
Reserve for unfunded lending commitments				1,000	1,000	1,000	1,000							1,000	1,000	1,000
Tax free loans	$ 20,362,000	$ 20,362,000	$ 20,362,000						$ 20,362,000	$ 20,362,000	$ 20,362,000	$ 20,362,000	$ 20,362,000				22,138,000
Commercial Real Estate | Maximum
Financing Receivable, Allowance for Credit Loss [Line Items]
Term of loan offering									20 years
Maximum loan to value ratio													80.00%
Residential Real Estate | Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Maximum loan to value ratio													80.00%
Loans held for sale term	30 years	30 years	30 years						30 years	30 years	30 years	30 years	30 years
Maximum loan to value ratio with PMI	95.00%	95.00%	95.00%						95.00%	95.00%	95.00%	95.00%	95.00%
Residential Real Estate | Residential Mortgage | Maximum
Financing Receivable, Allowance for Credit Loss [Line Items]
Term of loan offering									20 years
Loans held for sale term	30 years	30 years	30 years						30 years	30 years	30 years	30 years	30 years
Residential Real Estate | Home Equity Loan
Financing Receivable, Allowance for Credit Loss [Line Items]
Maximum loan to value ratio													80.00%
Residential Real Estate | Home Equity Loan | Maximum
Financing Receivable, Allowance for Credit Loss [Line Items]
Term of loan offering									15 years
Residential Real Estate | Home Equity Line of Credit
Financing Receivable, Allowance for Credit Loss [Line Items]
Maximum loan to value ratio													80.00%
Residential Real Estate | Home Equity Line of Credit | Maximum
Financing Receivable, Allowance for Credit Loss [Line Items]
Term of loan offering									20 years
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Unpaid principal balance	$ 5,446,000	$ 5,446,000	$ 5,446,000	6,166,000	6,166,000	6,166,000	6,166,000		$ 5,446,000	$ 5,446,000	$ 5,446,000	$ 5,446,000	$ 5,446,000	6,166,000	6,166,000	6,166,000	6,390,000
Agricultural
Financing Receivable, Allowance for Credit Loss [Line Items]
Unpaid principal balance	1,071,000	1,071,000	1,071,000	1,008,000	1,008,000	1,008,000	1,008,000		$ 1,071,000	1,071,000	1,071,000	1,071,000	$ 1,071,000	1,008,000	1,008,000	1,008,000	936,000
Agricultural | Maximum
Financing Receivable, Allowance for Credit Loss [Line Items]
Term of loan offering									10 years
Maximum loan to value ratio													70.00%
Real Estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans Receivable Held-for-sale, Amount	103,000	103,000	103,000						$ 103,000	103,000	103,000	103,000	$ 103,000				737,000
Unpaid principal balance	866,145,000	866,145,000	866,145,000	836,213,000	836,213,000	836,213,000	836,213,000		866,145,000	866,145,000	866,145,000	866,145,000	866,145,000	836,213,000	836,213,000	836,213,000	850,656,000
Reserve for unfunded lending commitments	$ 63,000	63,000	$ 63,000	$ 149,000	$ 149,000	149,000	$ 149,000		63,000	$ 63,000	63,000	$ 63,000	63,000	$ 149,000	149,000	$ 149,000
Number of contracts	1		1		1		1			1		1		2		2
Modified value of TDR		107,000				120,000					107,000				9,575,000
Recorded Investment		107,000				$ 120,000					107,000				$ 9,547,000
Financing Receivable, Modifications, Recorded Investment	$ 107,000	$ 107,000	$ 107,000						$ 107,000	$ 107,000	$ 107,000	$ 107,000	$ 107,000				10,019,000
Number of loans modified as troubled debt restructuring within previous 12 months, with subsequent payment default | loan			0
Real Estate | Unfunded Loan Commitment
Financing Receivable, Allowance for Credit Loss [Line Items]
Reserve for unfunded lending commitments																	$ 85,000
Real Estate | Term Modification
Financing Receivable, Allowance for Credit Loss [Line Items]
Number of contracts | loan							1									1
Real Estate | Payment Modification
Financing Receivable, Allowance for Credit Loss [Line Items]
Number of contracts | loan			1									1				1