Note 10 - Business Segment Reporting - Revenue by Major Source (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues	$ 3,314	$ 9,289	$ 10,851	$ 19,111
UNITED STATES
Revenues	3,125	6,807	9,466	13,867
BRAZIL
Revenues	164	2,358	1,145	5,001
Other Foreign Countries [Member]
Revenues	$ 25	$ 124	$ 240	$ 243