Note 9 - Stock Based Awards - Activity Under Stock Option Plan (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) $ / shares shares
Balances, number of shares (in shares) | shares	2,439,253
Balances, weighted average exercise price (in dollars per share) | $ / shares	$ 3.96
Options granted, number of shares (in shares) | shares	2,888,641
Options granted, weighted average exercise price (in dollars per share) | $ / shares	$ 1.61
Options cancelled, number of shares (in shares) | shares	(757,462)
Options cancelled, weighted average exercise price (in dollars per share) | $ / shares	$ 3.81
Options exercised, number of shares (in shares) | shares	0
Options exercised, weighted average exercise price (in dollars per share) | $ / shares	$ 0
Balances, number of shares (in shares) | shares	4,570,432
Balances, weighted average exercise price (in dollars per share) | $ / shares	$ 2.50
Balances, weighted average remaining contractual life (Year)	7 years 2 months 12 days
Balances, aggregate intrinsic value | $	$ 1,239
Outstanding and expected to vest, number of shares (in shares) | shares	4,100,681
Outstanding and expected to vest, weighted average exercise price (in dollars per share) | $ / shares	$ 2.54
Outstanding and expected to vest, weighted average remaining contractual life (Year)	7 years 1 month 6 days
Outstanding and expected to vest, aggregate intrinsic value | $	$ 1,184
Exercisable, number of shares (in shares) | shares	2,348,015
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 2.89
Exercisable, weighted average remaining contractual life (Year)	5 years 3 months 18 days
Exercisable, aggregate intrinsic value | $	$ 877