LOANS AND ALLOWANCE FOR LOAN LOSSES - Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Unpaid Principal Balance [Abstract]
Unpaid principal balance, total	$ 20,748		$ 20,748		$ 8,819
Recorded Investment [Abstract]
Recorded investment, total	20,617		20,617		8,731
Allowance for loan losses allocated	8,660		8,660		2,189
Average Recorded Investment [Abstract]
Average recorded investment, total	18,645	$ 9,280	14,111	$ 11,533
Interest Income, Accrual Method [Abstract]
Interest income, accrual method, total	44	14	61	49
Commercial Mortgages | Construction
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	262		262		307
Recorded Investment [Abstract]
With no related allowance, recorded investment	263		263		308
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	270	330	285	344
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	2	3	7	8
Commercial Mortgages | Commercial mortgages, other
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	3,305		3,305		4,007
With related allowance, Unpaid Principal Balance	10,221		10,221		1,902
Recorded Investment [Abstract]
With no related allowance, recorded investment	3,306		3,306		3,935
With related allowance, recorded investment	10,139		10,139		1,903
Allowance for loan losses allocated	2,519		2,519		446
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	3,372	4,339	3,630	4,257
With related allowance, average recorded investment	10,240	2,040	6,881	2,419
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	3	5	9	16
With related allowance, interest income, accrual method	0	1	0	4
Residential mortgages
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	436		436		424
Recorded Investment [Abstract]
With no related allowance, recorded investment	407		407		402
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	396	413	396	420
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	36	2	40	6
Consumer Loans | Home equity lines and loans
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	176		176		54
Recorded Investment [Abstract]
With no related allowance, recorded investment	153		153		55
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	156	59	134	61
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	3	1	4	2
Commercial and industrial | Commercial and agricultural
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	184		184		345
With related allowance, Unpaid Principal Balance	6,164		6,164		1,780
Recorded Investment [Abstract]
With no related allowance, recorded investment	184		184		346
With related allowance, recorded investment	6,165		6,165		1,782
Allowance for loan losses allocated	6,141		6,141		$ 1,743
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	228	526	277	673
With related allowance, average recorded investment	3,983	1,573	2,508	3,359
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	0	1	1	11
With related allowance, interest income, accrual method	$ 0	$ 1	$ 0	$ 2