Note 11 - Share-based Compensation - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Outstanding, shares, beginning balance (in shares)	2,738,107	2,395,663
Outstanding, weighted average exercise price (in dollars per share)	$ 5.84	$ 5.38
Granted, shares (in shares)	765,138	777,310
Granted, weighted average exercise price (in dollars per share)	$ 5.51	$ 5.93
Exercised / Released (in shares)	(116,616)	(407,225)
Exercised / Released, weighted average exercise price (in dollars per share)	$ 2.57	$ 3.43
Cancelled / Forfeited (in shares)	(841,667)	(10,000)
Cancelled / Forfeited, weighted average exercise price (in dollars per share)	$ 5.64	$ 6.43
Expired, shares (in shares)	(12,100)	(17,641)
Expired, weighted average exercise price (in dollars per share)	$ 2.90	$ 2.85
Outstanding, shares, ending balance (in shares)	2,532,862	2,738,107
Outstanding, weighted average exercise price (in dollars per share)	$ 5.97	$ 5.84
Outstanding, weighted-average remaining contractual term (Year)	6 years	6 years 4 months 28 days
Vested and exercisable, shares (in shares)	1,753,486	1,834,355
Vested and exercisable, weighted average exercise price (in dollars per share)	$ 6.06	$ 5.90
Vested and exercisable, weighted-average remaining contractual term (Year)	4 years 8 months 1 day	4 years 11 months 1 day