LOANS AND ALLOWANCE FOR CREDIT LOSSES - Impaired loans (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Modifications [Line Items]
Financing Receivable, Recorded Investment						$ 7,480,000
Unpaid principal balance	$ 881,038,000	$ 845,675,000	$ 881,038,000	$ 845,675,000		858,469,000
Related allowance	6,817,000	9,211,000	6,817,000	9,211,000	$ 7,157,000	8,274,000	$ 9,211,000	$ 9,160,000	$ 8,680,000
Recorded Investment
With no related allowance recorded	5,318,000		5,318,000			11,207,000
Total	5,318,000		5,318,000			11,207,000
Unpaid Principal Balance
With no related allowance recorded	7,307,000		7,307,000			14,174,000
With an allowance recorded	7,307,000		7,307,000			14,174,000
Total	7,307,000		7,307,000			14,174,000
Average Recorded Investment
With no related allowance recorded	5,367,000		5,362,000
Total	5,367,000		5,362,000
With no related allowance recorded		12,230,000		12,806,000
Total		12,230,000		12,806,000
Interest Income Recognized
With no related allowance recorded	6,000		18,000
Total	6,000		18,000
With no related allowance recorded		75,000		222,000
Total	6,000	75,000	18,000	222,000
Real Estate
Financing Receivable, Modifications [Line Items]
Unpaid principal balance	784,126,000		784,126,000			764,880,000
Related allowance	6,473,000		6,473,000		6,754,000	7,483,000
Recorded Investment
With no related allowance recorded	4,385,000		4,385,000
Total	4,385,000		4,385,000
Unpaid Principal Balance
With no related allowance recorded	6,374,000		6,374,000
With an allowance recorded	6,374,000		6,374,000
Total	6,374,000		6,374,000
Average Recorded Investment
With no related allowance recorded	4,423,000		4,402,000
Total	4,423,000		4,402,000
Agricultural
Financing Receivable, Modifications [Line Items]
Unpaid principal balance	708,000		708,000			860,000
Related allowance	1,000		1,000		1,000	6,000
Recorded Investment
With no related allowance recorded	309,000		309,000
Total	309,000		309,000
Unpaid Principal Balance
With no related allowance recorded	309,000		309,000
With an allowance recorded	309,000		309,000
Total	309,000		309,000
Average Recorded Investment
With no related allowance recorded	309,000		309,000
Total	309,000		309,000
Interest Income Recognized
With no related allowance recorded	6,000		18,000
Total	6,000		18,000
Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Unpaid principal balance	62,866,000		62,866,000			56,077,000
Related allowance	226,000		226,000		$ 268,000	504,000
Recorded Investment
With no related allowance recorded	624,000		624,000			973,000
Total	624,000		624,000			973,000
Unpaid Principal Balance
With no related allowance recorded	624,000		624,000			973,000
With an allowance recorded	624,000		624,000			973,000
Total	624,000		624,000			973,000
Average Recorded Investment
With no related allowance recorded	635,000		651,000
Total	$ 635,000		$ 651,000
With no related allowance recorded		987,000		997,000
Total		987,000		997,000
Interest Income Recognized
With no related allowance recorded		4,000		9,000
Total		4,000		9,000
Commercial and industrial
Financing Receivable, Modifications [Line Items]
Unpaid principal balance		85,855,000		85,855,000		86,999,000
Related allowance		718,000		718,000		704,000	718,000	675,000	681,000
Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Unpaid principal balance		600,068,000		600,068,000		611,549,000
Related allowance		6,047,000		6,047,000		5,932,000	6,047,000	5,954,000	5,408,000
Recorded Investment
With no related allowance recorded						9,495,000
Total						9,495,000
Unpaid Principal Balance
With no related allowance recorded						12,430,000
With an allowance recorded						12,430,000
Total						12,430,000
Average Recorded Investment
With no related allowance recorded		10,400,000		10,962,000
Total		10,400,000		10,962,000
Interest Income Recognized
With no related allowance recorded		71,000		213,000
Total		71,000		213,000
Residential Real Estate
Financing Receivable, Modifications [Line Items]
Unpaid principal balance		154,324,000		154,324,000		154,506,000
Related allowance		1,610,000		1,610,000		1,557,000	$ 1,610,000	$ 1,609,000	$ 1,539,000
Recorded Investment
With no related allowance recorded						739,000
Total						739,000
Unpaid Principal Balance
With no related allowance recorded						771,000
With an allowance recorded						771,000
Total						$ 771,000
Average Recorded Investment
With no related allowance recorded		843,000		847,000
Total		$ 843,000		$ 847,000