Note 4 - Segment Information - Geographical Segment Revenue (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenue		$ 9,443	$ 8,994	$ 29,760	$ 25,567
UNITED STATES
Revenue		2,004	2,921	8,349	8,541
Non-US [Member]
Revenue	[1]	$ 7,439	$ 6,073	$ 21,411	$ 17,026

[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.