Note 10 - Segment Reporting - Revenue by Country (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues from external customers	$ 7,775	$ 6,261	$ 13,463	$ 11,720
Revenues, percent	100.00%	100.00%	100.00%	100.00%
UNITED STATES
Revenues from external customers	$ 5,575	$ 1,970	$ 8,817	$ 3,795
Revenues, percent	72.00%	32.00%	66.00%	33.00%
UNITED KINGDOM
Revenues from external customers	$ 1,978	$ 4,206	$ 4,199	$ 7,644
Revenues, percent	25.00%	67.00%	31.00%	65.00%
All Others [Member]
Revenues from external customers	$ 222	$ 85	$ 447	$ 281
Revenues, percent	3.00%	1.00%	3.00%	2.00%