Note 8 - Share-based Compensation - Summary of Non-vested RSUs (Details) - Restricted Stock Units (RSUs) [Member]	6 Months Ended
	Jun. 30, 2022 $ / shares shares
Balance, shares (in shares) | shares	200,271
Balance, weighted average grant date fair value per share (in dollars per share) | $ / shares	$ 4.13
RSUs granted, shares (in shares) | shares	269,204
RSUs granted, weighted average grant date fair value per share (in dollars per share) | $ / shares	$ 1.49
RSUs released, shares (in shares) | shares	(311,929)
RSUs released, weighted average grant date fair value per share (in dollars per share) | $ / shares	$ 2.74
RSUs forfeited, shares (in shares) | shares	(87,718)
RSUs forfeited, weighted average grant date fair value per share (in dollars per share) | $ / shares	$ 1.49
Balance, shares (in shares) | shares	69,828
Balance, weighted average grant date fair value per share (in dollars per share) | $ / shares	$ 3.44