Shareholders' Equity - Summary of common shareholders' equity (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Shareholders' Equity
Beginning balance	$ 33,619	$ 35,113	$ 35,738	$ 35,366	$ 35,113	$ 35,366
Retirement benefits adjustment	12	13	22	22
Stock based compensation	33	41	42	25
Net Income (Loss)	(9,500)	(1,547)	(810)	325	(11,048)	(485)
Ending balance	24,164	33,619	34,992	35,738	24,164	34,992
Retained earnings
Shareholders' Equity
Beginning balance	22,194	23,741	26,183	25,858	23,741	25,858
Retirement benefits adjustment	0	0	0	0
Stock based compensation	0	0	0	0
Net Income (Loss)	(9,500)	(1,547)	(810)	325
Ending balance	12,694	22,194	25,373	26,183	12,694	25,373
Accumulated Other Comprehensive Loss
Shareholders' Equity
Beginning balance	(2,324)	(2,337)	(3,886)	(3,908)	(2,337)	(3,908)
Retirement benefits adjustment	12	13	22	22
Stock based compensation	0	0	0	0
Net Income (Loss)	0	0	0	0
Ending balance	(2,312)	(2,324)	(3,864)	(3,886)	(2,312)	(3,864)
Common Stock
Shareholders' Equity
Beginning balance	523	523	523	523	523	523
Retirement benefits adjustment	0	0	0	0
Stock based compensation	1	0	0	0
Net Income (Loss)	0	0	0	0
Ending balance	524	523	523	523	524	523
Capital in excess of par value
Shareholders' Equity
Beginning balance	14,573	14,556	14,502	14,500	14,556	14,500
Retirement benefits adjustment	0	0	0	0
Stock based compensation	14	17	7	2
Net Income (Loss)	0	0	0	0
Ending balance	14,587	14,573	14,509	14,502	14,587	14,509
ESOT
Shareholders' Equity
Beginning balance	(157)	(157)	(258)	(258)	(157)	(258)
Retirement benefits adjustment	0	0	0	0
Stock based compensation	0	0	0	0
Net Income (Loss)	0	0	0	0
Ending balance	(157)	(157)	(258)	(258)	(157)	(258)
Treasury stock
Shareholders' Equity
Beginning balance	(1,190)	(1,214)	(1,326)	(1,349)	(1,214)	(1,349)
Retirement benefits adjustment	0	0	0	0
Stock based compensation	18	24	35	23
Net Income (Loss)	0	0	0	0
Ending balance	$ (1,172)	$ (1,190)	$ (1,291)	$ (1,326)	$ (1,172)	$ (1,291)