LOANS AND ALLOWANCE FOR LOAN LOSSES - Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Unpaid Principal Balance [Abstract]
Unpaid principal balance, total	$ 12,068		$ 8,819
Recorded Investment [Abstract]
Recorded investment, total	11,973		8,731
Allowance for loan losses allocated	3,976		2,189
Average Recorded Investment [Abstract]
Average recorded investment, total	10,353	$ 13,784
Interest Income, Accrual Method [Abstract]
Interest income, accrual method, total	11	21
Commercial Mortgages | Construction
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	292		307
Recorded Investment [Abstract]
With no related allowance, recorded investment	293		308
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	301	359
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	2	3
Commercial Mortgages | Commercial mortgages, other
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	3,915		4,007
With related allowance, Unpaid Principal Balance	5,141		1,902
Recorded Investment [Abstract]
With no related allowance, recorded investment	3,843		3,935
With related allowance, recorded investment	5,142		1,903
Allowance for loan losses allocated	2,228		446
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	3,889	4,175
With related allowance, average recorded investment	3,523	2,797
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	5	5
With related allowance, interest income, accrual method	0	1
Residential mortgages
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	420		424
Recorded Investment [Abstract]
With no related allowance, recorded investment	392		402
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	397	426
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	2	2
Consumer Loans | Home equity lines and loans
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	164		54
Recorded Investment [Abstract]
With no related allowance, recorded investment	167		55
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	111	63
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	1	1
Commercial and industrial | Commercial and agricultural
Unpaid Principal Balance [Abstract]
With no related allowance, unpaid principal balance	304		345
With related allowance, Unpaid Principal Balance	1,832		1,780
Recorded Investment [Abstract]
With no related allowance, recorded investment	304		346
With related allowance, recorded investment	1,832		1,782
Allowance for loan losses allocated	1,748		$ 1,743
Average Recorded Investment [Abstract]
With no related allowance, average recorded investment	325	820
With related allowance, average recorded investment	1,807	5,144
Interest Income, Accrual Method [Abstract]
With no related allowance, interest income, accrual method	1	9
With related allowance, interest income, accrual method	$ 0	$ 0