Note 10 - Business Segment and Geographic Financial Data - Geographic Segment Financial Data (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenues	$ 8,155	$ 6,452	$ 16,334	$ 25,555
Assets	31,525		31,525		$ 31,606
UNITED STATES
Revenues	6,473	5,727	12,880	22,104
Assets	25,008		25,008		23,460
Non-US [Member]
Revenues	1,682	$ 725	3,454	$ 3,451
Assets	$ 6,517		$ 6,517		$ 8,146