Note 5 - Accounts Receivable and Revenues - Revenues by Product Line (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Revenues	$ 10,190	$ 7,574	$ 20,749	$ 16,179
UNITED STATES
Revenues	9,912	7,221	20,158	15,417
Other Countries [Member]
Revenues	$ 278	$ 353	$ 591	$ 762