Note 10 - Stock Compensation Plans - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Options outstanding, beginning of year (in shares)	126,500	126,000
Options cancelled (in shares)	0	0
Options exercised (in shares)	67,500
Options granted (in shares)	0	0
Options outstanding, end of year (in shares)	59,000	126,500
Options available for grant (in shares)	881,177	885,620
Options exercisable (in shares)	49,000	102,500
Exercised, exercise price range (in dollars per share)	$ 1.59	$ 0
Outstanding, exercise price range (in dollars per share)	17.35	8.94
Granted, weighted average exercise price (in dollars per share)	0	0
Exercisable, weighted average exercise price (in dollars per share)	16.81	5.61
Minimum [Member]
Exercised, exercise price range (in dollars per share)	1.52
Outstanding, exercise price range (in dollars per share)	3.50	1.52
Maximum [Member]
Exercised, exercise price range (in dollars per share)	1.72
Outstanding, exercise price range (in dollars per share)	$ 39.11	$ 39.11