Note 16 - Revision of Prior Period Financial Statements - Error Correction and Prior Period Adjustments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Deferred revenue, current portion	$ 944				$ 2,088
Total current liabilities	7,076	$ 8,830	$ 8,082	$ 9,771	11,262
Accumulated deficit	(132,248)				(130,006)
Total shareholders' equity	$ 39,125	$ 39,836	$ 8,886	$ 7,963	8,728				$ 9,773
Previously Reported [Member]
Deferred revenue, current portion					2,165
Total current liabilities					11,339	$ 10,544	$ 11,422	$ 12,856
Accumulated deficit					(130,083)
Total shareholders' equity					8,651	$ 8,622	$ 8,432	$ 9,401
Revision of Prior Period, Error Correction, Adjustment [Member]
Deferred revenue, current portion					(77)
Total current liabilities					(77)
Accumulated deficit					77
Total shareholders' equity					$ 77