Note 10 - Stock-based Compensation - Stock Option Activity (Details)	9 Months Ended
	Sep. 30, 2022 $ / shares shares
Options outstanding (in shares) | shares	233,384
Options outstanding, weighted-average exercise price (in dollars per share) | $ / shares	$ 97.78
Granted (in shares) | shares	118,434
Granted, weighted-average exercise price (in dollars per share) | $ / shares	$ 48.24
Exercised (in shares) | shares	(3,114)
Exercised, weighted-average exercise price (in dollars per share) | $ / shares	$ 30.58
Forfeited (in shares) | shares	(38,618)
Forfeited, weighted-average exercise price (in dollars per share) | $ / shares	$ 91.27
Expired (in shares) | shares	(34,201)
Expired (in dollars per share) | $ / shares	$ 89.71
Options outstanding (in shares) | shares	275,885
Options outstanding, weighted-average exercise price (in dollars per share) | $ / shares	$ 79.19
Options exercisable (in shares) | shares	108,659
Options exercisable, weighted-average exercise price (in dollars per share) | $ / shares	$ 91.50