Note 15 - Activity of Business Segments - Consolidated Net Sales and Long-lived Asset Information by Geographic Area (Details) - Reportable Geographical Components [Member] - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Net sales by geographic region
Consolidated sales	$ 46,665,000	$ 46,624,000
Long-lived assets by geographic region
Consolidated long-lived assets	3,943,000	3,244,000
UNITED STATES
Net sales by geographic region
Consolidated sales	45,748,000	45,595,000
Long-lived assets by geographic region
Consolidated long-lived assets	2,450,000	2,528,000
International Member
Net sales by geographic region
Consolidated sales	917,000	1,029,000
Long-lived assets by geographic region
Consolidated long-lived assets	$ 1,493,000	$ 716,000