Note 8 - Stock-based Compensation - Summary of Restricted Stock Activity (Details) - Restricted Stock [Member] shares in Thousands	6 Months Ended
	Jun. 30, 2022 $ / shares shares
Unvested, shares (in shares) | shares	471
Granted, shares (in shares) | shares	0
Vested, shares (in shares) | shares	(136)
Forfeited or canceled, shares (in shares) | shares	(20)
Unvested, shares (in shares) | shares	315
Unvested, weighted average price per share (in dollars per share) | $ / shares	$ 1.76
Granted, weighted average price per share (in dollars per share) | $ / shares	0
Vested, weighted average price per share (in dollars per share) | $ / shares	1.82
Forfeited or canceled, weighted average price per share (in dollars per share) | $ / shares	1.77
Unvested, weighted average price per share (in dollars per share) | $ / shares	$ 1.74