Change in accounting principle, Effect of Change on Statements of Cash Flows (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 Cash Flows [Abstract]
Net loss	$ (2,376)	$ (4,348)	$ (2,030)	$ (6,724)	$ (4,119)
Deferred income taxes		(1,355)		(2,227)	(1,153)
Inventories		(916)		$ (3,250)	2,334
Previously Reported [Member]
Condensed Consolidated Statements of Cash Flows [Abstract]
Net loss		(4,013)	(2,114)		(4,320)
Deferred income taxes		(1,262)			(1,209)
Inventories		(1,344)			2,591
Effect of Change [Member] | Change in Method of Inventory Valuation to Average Costing [Member]
Condensed Consolidated Statements of Cash Flows [Abstract]
Net loss		(335)	$ 84		201
Deferred income taxes		(93)			56
Inventories		$ 428			$ (257)