Note 10 - Financial Information about Geographic Areas - Consolidated Net Sales and Long-lived Asset Information by Geographic Area (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Consolidated sales	$ 14,722,000	$ 14,475,000	$ 49,756,000	$ 55,442,000
Reportable Geographical Components [Member]
Consolidated long-lived assets	5,773,000		5,773,000		$ 6,064,000
UNITED STATES | Reportable Geographical Components [Member]
Consolidated sales	14,569,000	14,244,000	48,385,000	52,836,000
Consolidated long-lived assets	4,428,000		4,428,000		4,623,000
International Member | Reportable Geographical Components [Member]
Consolidated sales	153,000	$ 231,000	1,371,000	$ 2,606,000
Consolidated long-lived assets	$ 1,345,000		$ 1,345,000		$ 1,441,000