Note 2 - Revenue Recognition - Significant Changes in Contract Assets and Deferred Revenue (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2022
Balance at beginning of period	$ 17	$ 46
Revenue recognized	34	50
Amounts collected or invoiced	0	(45)
Balance at end of period	51	51
Balance at beginning of period	1,164	1,138
Revenue recognized	(652)	(920)
Amounts collected or invoiced	65	359
Balance at end of period	$ 577	$ 577