Earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Numerator
Net income - basic and diluted	$ 12,453	$ 8,554
Denominator
Weighted average shares outstanding - basic (in shares)	1,468	1,459
Dilutive effect of common stock options (in shares)	0	0
Weighted average shares outstanding - diluted (in shares)	1,468	1,459
Earnings per share - basic (in dollars per share)	$ 8.48	$ 5.86
Earnings per share - diluted (in dollars per share)	$ 8.48	$ 5.86