Note 8 - Stock-based Compensation - Summary of RSU Activity (Details) - Restricted Stock Units (RSUs) [Member] $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2022 USD ($) $ / shares shares
Unvested, shares (in shares) | shares	1,200
Unvested, weighted average price per share (in dollars per share) | $ / shares	$ 3.83
Unvested, weighted average fair value | $	$ 4,596
Granted, shares (in shares) | shares	0
Granted, weighted average price per share (in dollars per share) | $ / shares	$ 0
Vested, shares (in shares) | shares	0
Vested, weighted average price per share (in dollars per share) | $ / shares	$ 0
Forfeited or canceled, shares (in shares) | shares	0
Forfeited or canceled, weighted average price per share (in dollars per share) | $ / shares	$ 0
Unvested, shares (in shares) | shares	1,200
Unvested, weighted average price per share (in dollars per share) | $ / shares	$ 3.83