Note 11 - 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, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Net sales by geographic region
Consolidated sales	$ 30,027,000	$ 30,027,000	$ 12,027,000	$ 73,681,000	$ 35,745,000
Long-lived assets by geographic region
Consolidated total long-lived assets	4,086,000	4,086,000		4,086,000		$ 3,943,000
Reportable Geographical Components [Member]
Net sales by geographic region
Consolidated sales	30,027,000
UNITED STATES
Long-lived assets by geographic region
Consolidated total long-lived assets	2,642,000	2,642,000		2,642,000		2,450,000
UNITED STATES | Reportable Geographical Components [Member]
Net sales by geographic region
Consolidated sales	24,295,000		11,806,000	62,461,000	35,004,000
International Member
Long-lived assets by geographic region
Consolidated total long-lived assets	1,444,000	$ 1,444,000		1,444,000		$ 1,493,000
International Member | Reportable Geographical Components [Member]
Net sales by geographic region
Consolidated sales	$ 5,732,000		$ 221,000	$ 11,220,000	$ 741,000