LOANS AND ALLOWANCE FOR LOAN LOSSES - Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Unpaid Principal Balance [Abstract]
Unpaid principal balance, total	$ 17,915		$ 17,915		$ 15,712
Recorded Investment [Abstract]
Recorded investment, total	15,741		15,741		15,665
Allowance for loan losses allocated	5,706		5,706		8,097
Average Recorded Investment [Abstract]
Average recorded investment, total	15,420	$ 14,323	15,501	$ 12,459
Interest Income, Accrual Method [Abstract]
Interest income, accrual method, total	19	8	27	17
Commercial Mortgages | Construction
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	219		219		247
Recorded Investment [Abstract]
With no related allowance, recorded investment	220		220		247
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	226	285	233	293
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	2	2	4	5
Commercial Mortgages | Commercial mortgages, other
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	6,887		6,887		3,501
With related allowance, Unpaid Principal Balance	2,197		2,197		5,093
Recorded Investment [Abstract]
With no related allowance, recorded investment	4,743		4,743		3,503
With related allowance, recorded investment	2,199		2,199		5,094
Allowance for loan losses allocated	213		213		2,097
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	3,982	3,640	3,822	3,738
With related allowance, average recorded investment	3,613	7,741	4,107	5,795
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	0	3	0	6
With related allowance, interest income, accrual method	8	0	8	0
Residential mortgages
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	1,190		1,190		554
Recorded Investment [Abstract]
With no related allowance, recorded investment	1,170		1,170		525
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	844	388	738	393
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	5	2	10	4
Consumer Loans | Home equity lines and loans
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	672		672		171
With related allowance, Unpaid Principal Balance	180		180		0
Recorded Investment [Abstract]
With no related allowance, recorded investment	657		657		149
With related allowance, recorded investment	180		180		0
Allowance for loan losses allocated	62		62		0
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	403	163	318	127
With related allowance, average recorded investment	90	0	60	0
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	2	1	3	1
With related allowance, interest income, accrual method	0	0	0	0
Commercial and industrial | Commercial and agricultural
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	1,089		1,089		133
With related allowance, Unpaid Principal Balance	5,481		5,481		6,013
Recorded Investment [Abstract]
With no related allowance, recorded investment	1,088		1,088		133
With related allowance, recorded investment	5,484		5,484		6,014
Allowance for loan losses allocated	5,431		5,431		$ 6,000
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	597	289	442	308
With related allowance, average recorded investment	5,665	1,817	5,781	1,805
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	0	0	0	1
With related allowance, interest income, accrual method	$ 2	$ 0	$ 2	$ 0