Note 11 - Business Segment and Geographic Financial Data - Geographic Segment Financial Data (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Revenues	$ 5,033	$ 3,778
Assets	51,043		$ 30,088
UNITED STATES
Revenues	4,463	3,097
Assets	45,379		24,524
Non-US [Member]
Revenues	570	$ 681
Assets	$ 5,664		$ 5,564