Shareholders' Equity - Summary of common shareholders' equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ 35,366	$ 33,737
Retirement obligation, net of taxes	22	15
Purchase of treasury shares		(81)
Stock based compensation	25	31
Net Income	325	541
Balance	35,738	34,243
Retained earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	25,858	21,803
Retirement obligation, net of taxes	0	0
Purchase of treasury shares		0
Stock based compensation	0	0
Net Income	325	541
Balance	26,183	22,344
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	(3,908)	(1,356)
Retirement obligation, net of taxes	22	15
Purchase of treasury shares		0
Stock based compensation	0	0
Net Income	0	0
Balance	(3,886)	(1,341)
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	523	523
Retirement obligation, net of taxes	0	0
Purchase of treasury shares		0
Stock based compensation	0	0
Net Income	0	0
Balance	523	523
Capital in excess of par value
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	14,500	14,481
Retirement obligation, net of taxes	0	0
Purchase of treasury shares		0
Stock based compensation	2	11
Net Income	0	0
Balance	14,502	14,492
ESOT
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	(258)	(359)
Retirement obligation, net of taxes	0	0
Purchase of treasury shares		0
Stock based compensation	0	0
Net Income	0	0
Balance	(258)	(359)
Treasury stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	(1,349)	(1,355)
Retirement obligation, net of taxes	0	0
Purchase of treasury shares		(81)
Stock based compensation	23	20
Net Income	0	0
Balance	$ (1,326)	$ (1,416)