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, 2017	Dec. 31, 2016
Net sales by geographic region
Consolidated sales	$ 44,025,000	$ 46,176,000
Long-lived assets by geographic region
Consolidated long-lived assets	3,158,000	2,646,000
UNITED STATES
Net sales by geographic region
Consolidated sales	43,169,000	45,068,000
Long-lived assets by geographic region
Consolidated long-lived assets	2,593,000	2,338,000
International Member
Net sales by geographic region
Consolidated sales	856,000	1,108,000
Long-lived assets by geographic region
Consolidated long-lived assets	$ 565,000	$ 308,000