LOANS AND ALLOWANCE FOR LOAN LOSSES - Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Unpaid Principal Balance [Abstract]
Unpaid principal balance, total	$ 14,364		$ 12,852
Recorded Investment [Abstract]
Recorded investment, total	13,440		11,926
Allowance for loan losses allocated	998		876
Average Recorded Investment [Abstract]
Average recorded investment, total	12,684	$ 14,607
Interest Income, Accrual Method [Abstract]
Interest income, accrual method, total	75	87
Commercial mortgages: | Construction
Unpaid Principal Balance [Abstract]
With no related allowance, Unpaid Principal Balance	1,558		277
Recorded Investment [Abstract]
With no related allowance, Recorded Investment	1,559		278
Average Recorded Investment [Abstract]
With no related allowance, Average Recorded Investment	919	348
Interest Income, Accrual Method [Abstract]
With no related allowance, Interest Income, Accrual Method	3	4
Commercial mortgages: | Commercial mortgages
Unpaid Principal Balance [Abstract]
With no related allowance, Unpaid Principal Balance	6,133		8,792
With related allowance, Unpaid Principal Balance	5,206		2,245
Recorded Investment [Abstract]
With no related allowance, Recorded Investment	6,144		7,857
With related allowance, Recorded Investment	4,266		2,247
Allowance for loan losses allocated	845		735
Average Recorded Investment [Abstract]
With no related allowance, Average Recorded Investment	7,000	7,395
With related allowance, Average Recorded Investment	3,257	4,845
Interest Income, Accrual Method [Abstract]
With no related allowance, Interest Income, Accrual Method	59	68
With related allowance, Interest Income, Accrual Method	1	1
Residential mortgages
Unpaid Principal Balance [Abstract]
With no related allowance, Unpaid Principal Balance	389		395
Recorded Investment [Abstract]
With no related allowance, Recorded Investment	390		396
Average Recorded Investment [Abstract]
With no related allowance, Average Recorded Investment	393	273
Interest Income, Accrual Method [Abstract]
With no related allowance, Interest Income, Accrual Method	2	0
Consumer Loans | Home equity lines and loans
Unpaid Principal Balance [Abstract]
With no related allowance, Unpaid Principal Balance	72		93
With related allowance, Unpaid Principal Balance	360		360
Recorded Investment [Abstract]
With no related allowance, Recorded Investment	72		95
With related allowance, Recorded Investment	360		360
Allowance for loan losses allocated	153		141
Average Recorded Investment [Abstract]
With no related allowance, Average Recorded Investment	84	107
With related allowance, Average Recorded Investment	360	364
Interest Income, Accrual Method [Abstract]
With no related allowance, Interest Income, Accrual Method	1	1
With related allowance, Interest Income, Accrual Method	0	0
Commercial and industrial | Commercial and agricultural:
Unpaid Principal Balance [Abstract]
With no related allowance, Unpaid Principal Balance	646		690
Recorded Investment [Abstract]
With no related allowance, Recorded Investment	649		$ 693
Average Recorded Investment [Abstract]
With no related allowance, Average Recorded Investment	671	1,266
With related allowance, Average Recorded Investment	0	9
Interest Income, Accrual Method [Abstract]
With no related allowance, Interest Income, Accrual Method	9	13
With related allowance, Interest Income, Accrual Method	$ 0	$ 0