EARNINGS PER SHARE - Computation of earnings per share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income	$ 6,256	$ 6,685	$ 8,457
Less: Preferred stock dividends declared			(158)
Net income applicable to common shareholders	6,256	6,685	8,299
Less: Undistributed earnings allocated to participating securities	(55)	(52)	(72)
Net income allocated to common stock	6,201	6,633	8,227
Weighted average common shares issued	2,779	2,755	2,730
Less: Unvested restricted stock awards	(24)	(22)	(24)
Weighted average common shares outstanding used to calculate basic earnings per common share	2,755	2,733	2,706
Add: Dilutive effect of stock options	19	16	17
Weighted average common shares outstanding used to calculate diluted earnings per common share	$ 2,774	$ 2,749	$ 2,723
Earnings per common share (basic)	$ 2.25	$ 2.43	$ 3.04
Earnings per common share (diluted)	$ 2.24	$ 2.41	$ 3.02