Note 6 - Stock Compensation Plans - Stock Options Outstanding and Exercisable (Details)	6 Months Ended
	Jun. 30, 2022 USD ($) $ / shares shares
Lower Range of Exercise Price (in dollars per share)	$ 3.50
Upper Range of Exercise Price (in dollars per share)	$ 39.11
Number Outstanding (in shares) | shares	59,000
Wgt. Avg. Contractual Life Remaining (Year)	6 years 1 month 6 days
Wgt. Avg. Exercise Price (in dollars per share)	$ 17.35
Aggregate Intrinsic Value | $	$ 534,070
Options Outstanding Exercise Price Range1 [Member]
Lower Range of Exercise Price (in dollars per share)	$ 3.50
Upper Range of Exercise Price (in dollars per share)	$ 3.86
Number Outstanding (in shares) | shares	13,000
Wgt. Avg. Contractual Life Remaining (Year)	4 years 8 months 12 days
Wgt. Avg. Exercise Price (in dollars per share)	$ 3.75
Aggregate Intrinsic Value | $	$ 298,720
Options Outstanding Exercise Price Range2 [Member]
Lower Range of Exercise Price (in dollars per share)	$ 7.80
Number Outstanding (in shares) | shares	8,000
Wgt. Avg. Contractual Life Remaining (Year)	5 years 10 months 24 days
Wgt. Avg. Exercise Price (in dollars per share)	$ 7.80
Aggregate Intrinsic Value | $	$ 102,750
Options Outstanding Exercise Price Range 3 [Member]
Lower Range of Exercise Price (in dollars per share)	$ 19.99
Number Outstanding (in shares) | shares	30,000
Wgt. Avg. Contractual Life Remaining (Year)	6 years 7 months 6 days
Wgt. Avg. Exercise Price (in dollars per share)	$ 19.99
Aggregate Intrinsic Value | $	$ 132,600
Options Outstanding Exercise Price Range 4 [Member]
Lower Range of Exercise Price (in dollars per share)	$ 39.11
Number Outstanding (in shares) | shares	8,000
Wgt. Avg. Contractual Life Remaining (Year)	6 years 10 months 24 days
Wgt. Avg. Exercise Price (in dollars per share)	$ 39.11