Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Computation of basic earnings per common share
Net income	$ 4,350	$ 4,871	$ 4,378
Weighted average common shares outstanding	4,407,254	4,406,005	4,497,825
Net effect of dilutive common share equivalents	4,220	1,264
Adjusted average shares outstanding - dilutive	4,411,474	4,407,269	4,497,825
Basic earnings per share	$ 0.99	$ 1.11	$ 0.97
Dilutive earnings per share	$ 0.99	$ 1.11	$ 0.97

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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