Note 6 - Equity - Stock Option Activity (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jul. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Outstanding, number of shares (in shares)		639,353
Outstanding, weighted average grant date fair value (in dollars per share)		$ 9.53
Outstanding, weighted average exercise price (in dollars per share)		$ 13.55
Outstanding, weighted average remaining contractual term (Year)		7 years 10 months 24 days	8 years 3 months 18 days
Outstanding, aggregate intrinsic value		$ 0	$ 0
Granted, number of shares (in shares)	224,964	267,468
Granted, weighted average grant date fair value (in dollars per share)		$ 4.96
Granted, weighted average exercise price (in dollars per share)		$ 5.66
Exercised, number of shares (in shares)		0
Exercised, weighted average grant date fair value (in dollars per share)		$ 0
Exercised, weighted average exercise price (in dollars per share)		$ 0
Forfeited, number of shares (in shares)		(3,334)
Forfeited, weighted average grant date fair value (in dollars per share)		$ 5.34
Forfeited, weighted average exercise price (in dollars per share)		$ 6.36
Outstanding, number of shares (in shares)		903,487	639,353
Outstanding, weighted average grant date fair value (in dollars per share)		$ 8.19	$ 9.53
Outstanding, weighted average exercise price (in dollars per share)		$ 11.24	$ 13.55
Exercisable, number of shares (in shares)		364,852
Exercisable, weighted average grant date fair value (in dollars per share)		$ 11.23
Exercisable, weighted average exercise price (in dollars per share)		$ 16.39
Exercisable, weighted average remaining contractual term (Year)		6 years 10 months 24 days
Exercisable, aggregate intrinsic value		$ 0