Note 3 - Stocked-based Compensation - Stock Option Activity (Details)	3 Months Ended
	Mar. 31, 2023 $ / shares shares
Options outstanding, Options (in shares) | shares	410,615
Options outstanding, Weighted average price (in dollars per share) | $ / shares	$ 3.50
Granted, Options (in shares) | shares	0
Granted, Weighted average price (in dollars per share) | $ / shares	$ 0
Exercised, Options (in shares) | shares	(109,250)
Exercised, Weighted average price (in dollars per share) | $ / shares	$ 3.20
Canceled/expired/forfeited, Options (in shares) | shares	0
Canceled/expired/forfeited, Weighted average price (in dollars per share) | $ / shares	$ 0
Options, Options (in shares) | shares	301,365
Options outstanding, Weighted average price (in dollars per share) | $ / shares	$ 3.61
Options exercisable, Options (in shares) | shares	286,665
Options exercisable, Weighted average price (in dollars per share) | $ / shares	$ 3.59