LOANS AND ALLOWANCE FOR LOAN LOSSES - Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Unpaid Principal Balance
Unpaid principal balance, total	$ 19,782		$ 19,782		$ 16,546
Recorded Investment
Recorded investment, total	13,128		13,128		10,589
Allowance for Loan Losses Allocated	3,244		3,244		1,527
Average Recorded Investment
Average recorded investment, total	11,525	$ 15,420	11,213	$ 15,501
Interest Income Recognized
Interest income, accrual method, total	35	19	67	27
Commercial and agricultural: | Commercial and industrial
Average Recorded Investment
With no related allowance, average recorded investment			1,869	442
With related allowance, average recorded investment			1,478	5,781
Commercial and agricultural: | Commercial and industrial
Unpaid Principal Balance
With no related allowance, unpaid principal balance	1,785		1,785		1,960
With related allowance, unpaid principal balance	5,357		5,357		5,228
Recorded Investment
With no related allowance, recorded investment	1,785		1,785		1,963
With related allowance, recorded investment	1,478		1,478		1,437
Allowance for Loan Losses Allocated	1,389		1,389		1,401
Average Recorded Investment
With no related allowance, average recorded investment	1,823	597
With related allowance, average recorded investment	1,498	5,665
Interest Income Recognized
With no related allowance, interest income, accrual method	13	0	26	0
With related allowance, interest income, accrual method	0	2	2	2
Commercial mortgages: | Construction
Unpaid Principal Balance
With no related allowance, unpaid principal balance	159		159		188
Recorded Investment
With no related allowance, recorded investment	160		160		189
Average Recorded Investment
With no related allowance, average recorded investment	168	226	175	233
Interest Income Recognized
With no related allowance, interest income, accrual method	2	2	3	4
Commercial mortgages: | Commercial mortgages, other
Unpaid Principal Balance
With no related allowance, unpaid principal balance	7,340		7,340		6,814
With related allowance, unpaid principal balance	3,808		3,808		258
Recorded Investment
With no related allowance, recorded investment	4,679		4,679		4,760
With related allowance, recorded investment	3,726		3,726		168
Allowance for Loan Losses Allocated	1,781		1,781		74
Average Recorded Investment
With no related allowance, average recorded investment	4,780	3,982	4,774	3,822
With related allowance, average recorded investment	1,946	3,613	1,353	4,107
Interest Income Recognized
With no related allowance, interest income, accrual method	8	0	15	0
With related allowance, interest income, accrual method	0	8	0	8
Residential mortgages
Unpaid Principal Balance
With no related allowance, unpaid principal balance	970		970		1,283
Recorded Investment
With no related allowance, recorded investment	954		954		1,271
Average Recorded Investment
With no related allowance, average recorded investment	959	844	1,063	738
Interest Income Recognized
With no related allowance, interest income, accrual method	10	5	18	10
Consumer loans: | Home equity lines and loans
Unpaid Principal Balance
With no related allowance, unpaid principal balance	207		207		645
With related allowance, unpaid principal balance	156		156		170
Recorded Investment
With no related allowance, recorded investment	190		190		631
With related allowance, recorded investment	156		156		170
Allowance for Loan Losses Allocated	74		74		$ 52
Average Recorded Investment
With no related allowance, average recorded investment	193	403	339	318
With related allowance, average recorded investment	158	90	162	60
Interest Income Recognized
With no related allowance, interest income, accrual method	2	2	3	3
With related allowance, interest income, accrual method	$ 0	$ 0	$ 0	$ 0