Shareholders' Equity - Summary of common shareholders' equity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ 33,737	$ 33,532
Retirement obligation, net of taxes	2,451	134
Purchase of treasury shares	(81)	(100)
Stock based compensation	106	339
Net Income	4,055	100
Net income	4,055	100
Balance	35,366	33,737
Retained earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	21,803	21,703
Net income	4,055	100
Balance	25,858	21,803
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	(1,356)	(1,121)
Retirement obligation, net of taxes	2,552	235
Balance	(3,908)	(1,356)
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	523	523
Balance	523	523
Capital in excess of par value
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	14,481	14,358
Stock based compensation	19	123
Balance	14,500	14,481
ESOT
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	(359)	(460)
Retirement obligation, net of taxes	(101)	(101)
Balance	(258)	(359)
Treasury stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	(1,355)	(1,471)
Purchase of treasury shares	(81)	(100)
Stock based compensation	87	216
Balance	$ (1,349)	$ (1,355)