Note 14 - 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, 2018	Dec. 31, 2017
Net sales by geographic region
Consolidated sales	$ 46,624,000	$ 44,025,000
Long-lived assets by geographic region
Consolidated long-lived assets	3,244,000	3,158,000
UNITED STATES
Net sales by geographic region
Consolidated sales	45,595,000	43,169,000
Long-lived assets by geographic region
Consolidated long-lived assets	2,528,000	2,593,000
International Member
Net sales by geographic region
Consolidated sales	1,029,000	856,000
Long-lived assets by geographic region
Consolidated long-lived assets	$ 716,000	$ 565,000