Note 8 - Shareholders' Equity - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Options outstanding, December 31, 2020 (in shares)	427,580	568,740
Options outstanding, December 31, 2020 (in dollars per share)	$ 3.50	$ 3.42
Exercised (in shares)	(21,665)	(134,494)
Exercised (in dollars per share)	$ 3.70	$ 3.17
Canceled/expired/forfeited (in shares)	(14,900)	(6,666)
Canceled/expired/forfeited (in dollars per share)	$ 3.93	$ 0
Options outstanding, December 31, 2021 (in shares)	410,615	427,580
Options outstanding, December 31, 2021 (in dollars per share)	$ 3.50	$ 3.50
Options exercisable, December 31, 2022 (in shares)	395,915
Options exercisable, December 31, 2022 (in dollars per share)	$ 3.48
Employees and Directors [Member]
Granted to employees and directors (in shares)	19,600	0
Granted to employees and directors (in dollars per share)	$ 3.99	$ 0