Note 8 - Stock Based Awards - Activity Under Stock Option Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2023
Balances, number of shares (in shares)	4,570,432
Balances, weighted average exercise price (in dollars per share)	$ 2.50
Options granted, number of shares (in shares)	3,207,654
Options granted, weighted average exercise price (in dollars per share)	$ 1.69
Options expired, number of shares (in shares)	(43,838)
Options expired, weighted average exercise price (in dollars per share)	$ 6.18
Options forfeited, number of shares (in shares)	(20,000)
Options forfeited, weighted average exercise price (in dollars per share)	$ 4.15
Balances, number of shares (in shares)	7,714,248
Balances, weighted average exercise price (in dollars per share)	$ 2.14
Balances, weighted average remaining contractual life (Year)	8 years
Balances, aggregate intrinsic value	$ 1,108
Outstanding and expected to vest, number of shares (in shares)	6,794,867
Outstanding and expected to vest, weighted average exercise price (in dollars per share)	$ 2.19
Outstanding and expected to vest, weighted average remaining contractual life (Year)	7 years 9 months 18 days
Outstanding and expected to vest, aggregate intrinsic value	$ 1,083
Exercisable, number of shares (in shares)	2,970,492
Exercisable, weighted average exercise price (in dollars per share)	$ 2.63
Exercisable, weighted average remaining contractual life (Year)	5 years 9 months 18 days
Exercisable, aggregate intrinsic value	$ 933