Note 10 - Stock Compensation Plans - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Options outstanding, beginning of year (in shares)	59,000	126,500
Options cancelled (in shares)	0	0
Stock options exercised (in shares)	0	67,500
Options granted (in shares)	0	0
Options outstanding, end of year (in shares)	59,000	59,000
Options available for grant (in shares)	932,369	881,177
Options exercisable (in shares)	59,000	49,000
Exercised, exercise price range (in dollars per share)	$ 0	$ 1.59
Outstanding, exercise price range (in dollars per share)	17.35	17.35
Granted, weighted average exercise price (in dollars per share)	0	0
Exercisable, weighted average exercise price (in dollars per share)	17.35	16.81
Minimum [Member]
Exercised, exercise price range (in dollars per share)		1.52
Outstanding, exercise price range (in dollars per share)	3.50	3.50
Maximum [Member]
Exercised, exercise price range (in dollars per share)		1.72
Outstanding, exercise price range (in dollars per share)	$ 39.11	$ 39.11