Note 3 - Stocked-based Compensation - Stock Option Activity (Details)	3 Months Ended
	Mar. 31, 2022 $ / shares shares
Options outstanding (in shares) | shares	427,580
Options outstanding (in dollars per share) | $ / shares	$ 3.50
Granted to employees and non-employee directors (in shares) | shares	0
Granted to employees and non-employee directors (in dollars per share) | $ / shares	$ 0
Exercised (in shares) | shares	0
Exercised (in dollars per share) | $ / shares	$ 0
Canceled/expired/forfeited (in shares) | shares	0
Canceled/expired/forfeited (in dollars per share) | $ / shares	$ 0
Options outstanding (in shares) | shares	427,580
Options outstanding (in dollars per share) | $ / shares	$ 3.50
Options exercisable (in shares) | shares	322,580
Options exercisable (in dollars per share) | $ / shares	$ 3.47