Change in accounting principle, Effect of Change on Statements of Changes in Shareholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Condensed Consolidated Statements of Changes in Shareholders' Equity [Abstract]
Beginning balance	$ 34,771	$ 38,984	$ 28,369	$ 38,984	$ 30,125
Net loss	(2,376)	(4,348)	(2,030)	(6,724)	(4,119)
Ending balance	32,672	34,771	26,963	32,672	26,963
Retained Earnings [Member]
Condensed Consolidated Statements of Changes in Shareholders' Equity [Abstract]
Beginning balance	11,218	15,566	17,518	15,566	19,607
Net loss	(2,376)		(2,030)	(6,724)	(4,119)
Ending balance	8,842	11,218	15,488	8,842	15,488
Previously Reported [Member]
Condensed Consolidated Statements of Changes in Shareholders' Equity [Abstract]
Beginning balance	35,113	38,991	28,363	38,991	30,236
Net loss		(4,013)	(2,114)		(4,320)
Ending balance		35,113	26,873		26,873
Previously Reported [Member] | Retained Earnings [Member]
Condensed Consolidated Statements of Changes in Shareholders' Equity [Abstract]
Beginning balance	11,560	15,573	17,512	15,573	19,718
Ending balance		11,560	15,398		15,398
Effect of Change [Member] | Change in Method of Inventory Valuation to Average Costing [Member]
Condensed Consolidated Statements of Changes in Shareholders' Equity [Abstract]
Beginning balance	(342)	(7)	6	(7)	(111)
Net loss		(335)	84		201
Ending balance		(342)	90		90
Effect of Change [Member] | Retained Earnings [Member] | Change in Method of Inventory Valuation to Average Costing [Member]
Condensed Consolidated Statements of Changes in Shareholders' Equity [Abstract]
Beginning balance	$ (342)	(7)	6	$ (7)	(111)
Ending balance		$ (342)	$ 90		$ 90