Note 12 - Stockholders' Equity - Option Activity for Stock Option Plans (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Outstanding, options (in shares)	889,636
Outstanding, weighted average exercise price, options (in dollars per share)	$ 8.57
Outstanding, weighted average remaining contractual life, options (Year)	6 years 9 months 18 days	8 years 8 months 12 days
Expired, options (in shares)	(766)
Expired, weighted average exercise price, options (in dollars per share)	$ 272.21
Forfeited/cancelled, options (in shares)	(535,450)
Forfeited/cancelled, weighted average exercise price, options (in dollars per share)	$ 5.89
Outstanding, options (in shares)	353,420	889,636
Outstanding, weighted average exercise price, options (in dollars per share)	$ 12.04	$ 8.57
Vested and expected to vest, options (in shares)	326,596
Vested and expected to vest, weighted average exercise price, options (in dollars per share)	$ 12.46
Vested and expected to vest, weighted average remaining contractual life, options (Year)	6 years 8 months 12 days
Exercisable, options (in shares)	279,520
Exercisable, weighted average exercise price, options (in dollars per share)	$ 13.29
Exercisable, weighted average remaining contractual life, options (Year)	6 years 7 months 6 days