Note 9 - Intangible Assets, Net - Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Intangible assets, gross amount	$ 8,051	$ 7,655
Intangible assets, accumulated amortization	(4,020)	(3,574)
Intangible assets, net	4,031	4,081
Patents [Member]
Intangible assets, gross amount	8,029	7,638
Intangible assets, accumulated amortization	(4,005)	(3,560)
Intangible assets, net	4,024	4,078
Trademarks [Member]
Intangible assets, gross amount	22	17
Intangible assets, accumulated amortization	(15)	(14)
Intangible assets, net	$ 7	$ 3