Change in accounting principle, Effect of Change on Statements of Operations (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Condensed Consolidated Statements of Operations [Abstract]
Cost of sales	$ 9,663	$ 6,332	$ 23,988	$ 17,187
Gross profit	8,193	4,305	16,193	11,076
Operating loss	387	(1,616)	(8,171)	(6,780)
Income (loss) before income taxes	466	459	(8,483)	(4,847)
Income tax benefit	62	442	2,287	1,629
Net income (loss)	$ 528	$ 901	$ (6,196)	$ (3,218)
Net income (loss) per common share [Abstract]
Basic (in dollars per share)	$ 0.05	$ 0.1	$ (0.63)	$ (0.35)
Diluted (in dollars per share)	$ 0.05	$ 0.09	$ (0.63)	$ (0.35)
Shares used in per-share calculation [Abstract]
Basic (in shares)	9,911	9,408	9,902	9,112
Diluted (in shares)	9,911	9,846	9,902	9,112
Previously Reported [Member]
Condensed Consolidated Statements of Operations [Abstract]
Cost of sales		$ 6,320		$ 17,432
Gross profit		4,317		10,831
Operating loss		(1,604)		(7,025)
Income (loss) before income taxes		471		(5,092)
Income tax benefit		439		1,682
Net income (loss)		$ 910		$ (3,410)
Net income (loss) per common share [Abstract]
Basic (in dollars per share)		$ 0.1		$ (0.37)
Diluted (in dollars per share)		$ 0.09		$ (0.37)
Shares used in per-share calculation [Abstract]
Basic (in shares)		9,408		9,112
Diluted (in shares)		9,846		9,112
Effect of Change [Member] | Change in Method of Inventory Valuation to Average Costing [Member]
Condensed Consolidated Statements of Operations [Abstract]
Cost of sales		$ 12		$ (245)
Gross profit		(12)		245
Operating loss		(12)		245
Income (loss) before income taxes		(12)		245
Income tax benefit		3		(53)
Net income (loss)		$ (9)		$ 192
Net income (loss) per common share [Abstract]
Basic (in dollars per share)		$ 0		$ 0.02
Diluted (in dollars per share)		$ 0		$ 0.02