Note 14 - Business Segment Reporting - Revenue by Major Source (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues	$ 5,335	$ 5,174	$ 3,314	$ 7,537	$ 8,715	$ 9,852	$ 9,289	$ 9,822	$ 21,360	$ 37,678	$ 42,674
UNITED STATES
Revenues									19,486	27,329	29,189
BRAZIL
Revenues									1,344	9,819	13,046
Other Foreign Countries [Member]
Revenues									$ 530	$ 530	$ 439