Note 4 - Segment Information - Geographical Segment Revenue (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2023	Mar. 31, 2022
Revenue		$ 7,843	$ 7,411
UNITED STATES
Revenue		2,767	2,363
Non-US [Member]
Revenue	[1]	$ 5,076	$ 5,048

[1] Revenue from the Central Banks, consisting of a consortium of central banks around the world, is classified as international revenue. Reporting revenue by country for this customer is not practicable.