Note 3 - Revenue - Timing of Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues	$ 7,559	$ 8,155	$ 17,810	$ 16,334
Transferred at Point in Time [Member]
Revenues	6,387	5,108	16,042	11,089
Transferred over Time [Member]
Revenues	$ 1,172	$ 3,047	$ 1,768	$ 5,245