Note I - Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Finite-Lived Intangible Assets [Table Text Block]

	December 31, 2019
	Gross		Accumulated			Intangible
	Amount		amortization			assets, net
Patents	$	7,638	$	(3,560	)	$	4,078
Trademarks		17		(14	)	$	3
Total intangible assets	$	7,655	$	(3,574	)	$	4,081

	December 31, 2018
	Gross		Accumulated			Intangible
	Amount		amortization			assets, net
Patents	$	6,983	$	(3,008	)	$	3,975
Trademarks		15		(13	)		2
Total intangible assets	$	6,998	$	(3,021	)	$	3,977

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

2020	$	537
2021		537
2022		537
2023		537
2024		537
thereafter		1,396
	$	4,081