Note 3 - Revenue Recognition - Revenues Disaggregated by Geography (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
Revenues	$ 6,216	$ 8,155	$ 4,401	$ 3,778	$ 4,912	$ 6,452	$ 8,948	$ 10,155	$ 22,550	$ 30,467
UNITED STATES
Revenues									18,622	25,882
Americas, Excluding United States [Member]
Revenues									549	777
Europe [Member]
Revenues									1,656	2,322
Asia [Member]
Revenues									1,723	1,486
Non-US [Member]
Revenues									$ 3,928	$ 4,585