Calculation of earnings per share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net income applicable to common shareholders	$ 16,473	$ 11,940	$ 11,136
Less: Undistributed earnings allocated to participating securities	(248)	(165)	(160)
Net income allocated to common shareholders	16,225	11,775	10,976
Weighted average common shares issued	2,855	2,837	2,817
Less: Unvested restricted stock awards	(43)	(39)	(35)
Weighted average common shares outstanding used to calculate basic earnings per common share	2,812	2,798	2,782
Add: Dilutive effect of performance based restricted stock awards and stock options	24	8	12
Weighted average common shares outstanding used to calculate diluted earnings per common share	$ 2,836	$ 2,806	$ 2,794
Earnings per common share (basic)	$ 5.77	$ 4.21	$ 3.95
Earnings per common share (diluted)	$ 5.72	$ 4.20	$ 3.93