LOANS AND ALLOWANCE FOR CREDIT LOSSES - Impaired loans (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Modifications [Line Items]
Financing Receivable, Recorded Investment						$ 7,480,000
Unpaid principal balance	$ 871,239,000	$ 804,820,000	$ 871,239,000	$ 804,820,000		858,469,000
Related allowance	7,157,000	9,160,000	7,157,000	9,160,000	$ 7,142,000	8,274,000	$ 8,937,000	$ 8,680,000
Recorded Investment
Total	5,398,000		5,398,000			11,207,000
Unpaid Principal Balance
With an allowance recorded	7,419,000		7,419,000			14,174,000
Total	7,419,000		7,419,000			14,174,000
Average Recorded Investment
Total	5,329,000		5,358,000
Total		12,646,000		13,100,000
Interest Income Recognized
Total	6,000		12,000
Total	6,000	73,000	12,000	147,000
Real Estate
Financing Receivable, Modifications [Line Items]
Unpaid principal balance	774,688,000		774,688,000			764,880,000
Related allowance	6,754,000		6,754,000		6,735,000	7,483,000
Recorded Investment
With no related allowance recorded	4,445,000		4,445,000
Total	4,445,000		4,445,000
Unpaid Principal Balance
With no related allowance recorded	6,466,000		6,466,000
With an allowance recorded	6,466,000		6,466,000
Total	6,466,000		6,466,000
Average Recorded Investment
With no related allowance recorded	4,367,000		4,390,000
Total	4,367,000
Total			4,390,000
Agricultural
Financing Receivable, Modifications [Line Items]
Unpaid principal balance	862,000		862,000			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		12,000
Total	6,000		12,000
Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Unpaid principal balance	61,313,000		61,313,000			56,077,000
Related allowance	268,000		268,000		$ 265,000	504,000
Recorded Investment
With no related allowance recorded	644,000		644,000
Total	644,000		644,000
Unpaid Principal Balance
With no related allowance recorded	644,000		644,000
With an allowance recorded	644,000		644,000
Total	644,000		644,000
Average Recorded Investment
With no related allowance recorded	653,000		659,000
Total	$ 653,000		$ 659,000
Commercial and industrial
Financing Receivable, Modifications [Line Items]
Unpaid principal balance		82,539,000		82,539,000		86,999,000
Related allowance		675,000		675,000		704,000	665,000	681,000
Recorded Investment
With no related allowance recorded						973,000
Total						973,000
Unpaid Principal Balance
With no related allowance recorded						973,000
With an allowance recorded						973,000
Total						973,000
Average Recorded Investment
With no related allowance recorded		998,000		1,004,000
Total		998,000		1,004,000
Interest Income Recognized
With no related allowance recorded		3,000		5,000
Total		3,000		5,000
Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Unpaid principal balance		568,258,000		568,258,000		611,549,000
Related allowance		5,954,000		5,954,000		5,932,000	5,759,000	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		10,801,000		11,247,000
Total		10,801,000		11,247,000
Interest Income Recognized
With no related allowance recorded		70,000		142,000
Total		70,000		142,000
Residential Real Estate
Financing Receivable, Modifications [Line Items]
Unpaid principal balance		148,621,000		148,621,000		154,506,000
Related allowance		1,609,000		1,609,000		1,557,000	$ 1,538,000	$ 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		847,000		849,000
Total		$ 847,000		$ 849,000