Note 2 - Revenue Recognition - Significant Changes in Contract Assets and Deferred Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Receivables	$ 4,914	$ 6,177
Short-term contract assets	46	456
Long-term contract assets	0	0
Short-term contract liabilities (deferred revenue)	944	2,088
Long-term contract liabilities (deferred revenue)	194	28
Transferred to receivables from contract assets outstanding at the beginning of the period	0	47
Revenue recognized that was included in contract liabilities at the beginning of the period	$ 1,273	$ 1,633