Note 10 - Stock-based Compensation - Stock Option Activity (Details)	6 Months Ended
	Jun. 30, 2021 $ / shares shares
Options outstanding, number of shares (in shares) | shares	438,200
Options outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 6.25
Granted, number of shares (in shares) | shares	282,404
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 11.77
Exercised, number of shares (in shares) | shares	(145,575)
Exercised, weighted average exercise price (in dollars per share) | $ / shares	$ 6.89
Forfeited, number of shares (in shares) | shares	(80,550)
Forfeited, weighted average exercise price (in dollars per share) | $ / shares	$ 9.55
Options outstanding, number of shares (in shares) | shares	494,479
Options outstanding, weighted average exercise price (in dollars per share) | $ / shares	$ 8.67