Summary of Significant Accounting Policies - Net earnings per common share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Summary of Significant Accounting Policies
Net earnings	$ 7,482	$ 5,500	$ 6,889
Allocation to nonvested restricted stock awards	(115)	(87)	(111)
Net earnings available to common stockholders	$ 7,367	$ 5,413	$ 6,778
Weighted-average shares outstanding - basic and diluted	35,836,000	35,946,000	36,130,000
Net earnings per common share - basic and diluted	$ 0.21	$ 0.15	$ 0.19
Options outstanding (in shares)	0	0	0

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The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or 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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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities, and addition from assumption of issuance of common shares for dilutive potential common shares; of income (loss) available to common shareholders.

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Number of options outstanding, including both vested and non-vested options.

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Average number of shares or units issued and outstanding that are used in calculating basic and diluted earnings per share (EPS).

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