Note 9 - Stock-based Compensation - Summary of RSU Activity (Details) - Restricted Stock Units (RSUs) [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Unvested, shares (in shares)	900	1,200
Unvested, estimated fair value per share (in dollars per share)	$ 3.83	$ 3.83
Granted, shares (in shares)	900	0
Granted, estimated fair value per share (in dollars per share)	$ 3.93	$ 0
Granted, weighted average fair value	$ 3,537	$ 0
Vested, shares (in shares)	(300)	(300)
Vested, estimated fair value per share (in dollars per share)	$ 3.83	$ 3.83
Vested, weighted average fair value	$ (1,149)	$ (1,149)
Forfeited or canceled, shares (in shares)	0	0
Forfeited or canceled, estimated fair value per share (in dollars per share)	$ 0	$ 0
Unvested, weighted average fair value	$ 5,745	$ 3,447
Unvested, shares (in shares)	1,500	900
Unvested, estimated fair value per share (in dollars per share)	$ 3.83	$ 3.83