Note 10 - Financial Information about Geographic Areas - Consolidated Net Sales and Long-lived Asset Information by Geographic Area (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Consolidated sales	$ 17,373,000	$ 17,806,000	$ 35,034,000	$ 40,967,000
Reportable Geographical Components [Member]
Consolidated long-lived assets	5,848,000		5,848,000		$ 6,064,000
UNITED STATES | Reportable Geographical Components [Member]
Consolidated sales	16,740,000	17,694,000	33,815,000	38,592,000
Consolidated long-lived assets	4,466,000		4,466,000		4,623,000
International Member | Reportable Geographical Components [Member]
Consolidated sales	633,000	$ 112,000	1,219,000	$ 2,375,000
Consolidated long-lived assets	$ 1,382,000		$ 1,382,000		$ 1,441,000