QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly financial data
Interest Income	$ 9,980	$ 9,719	$ 9,584	$ 9,376	$ 9,164	$ 9,206	$ 9,086	$ 9,098	$ 38,659	$ 36,554	$ 33,185
Net Interest Income	8,682	8,424	8,361	8,178	8,068	8,066	7,985	8,009	33,645	32,128	29,135
Net Income	$ 2,578	$ 2,592	$ 2,410	$ 3,137	$ 2,285	$ 2,365	$ 2,082	$ 1,837	$ 10,717	$ 8,569	$ 6,832
Basic earnings per share (in dollars per share)	$ 0.87	$ 0.87	$ 0.81	$ 1.06	$ 0.77	$ 0.79	$ 0.70	$ 0.61	$ 3.61	$ 2.87	$ 2.40
Diluted earnings per share (in dollars per share)	$ 0.87	$ 0.87	$ 0.81	$ 1.06	$ 0.77	$ 0.79	$ 0.70	$ 0.61	$ 3.61	$ 2.87	$ 2.40
Gain bank premises				$ 1,200					$ 1,200
Increase in income due to sale of property				$ 789