Note I - Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Intangible assets, gross amount	$ 7,655	$ 6,998
Intangible assets, accumulated amortization	(3,574)	(3,021)
Intangible assets, net	4,081	3,977
Patents [Member]
Intangible assets, gross amount	7,638	6,983
Intangible assets, accumulated amortization	(3,560)	(3,008)
Intangible assets, net	4,078	3,975
Trademarks [Member]
Intangible assets, gross amount	17	15
Intangible assets, accumulated amortization	(14)	(13)
Intangible assets, net	$ 3	$ 2