Note 5 - Stock-based Compensation - Stock Options Outstanding and Exercisable (Details)	9 Months Ended
	Sep. 30, 2023 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
Outstanding Weighted Average Contractual Life Remaining (Year)	4 years 10 months 24 days
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 17.35
Outstanding Aggregate Intrinsic Value | $	$ 309,160
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
Outstanding Weighted Average Contractual Life Remaining (Year)	3 years 6 months
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 3.75
Outstanding Aggregate Intrinsic Value | $	$ 211,260
Options Outstanding Exercise Price Range2 [Member]
Upper Range of Exercise Price (in dollars per share)	$ 7.80
Number Outstanding (in shares) | shares	8,000
Outstanding Weighted Average Contractual Life Remaining (Year)	4 years 8 months 12 days
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 7.80
Outstanding Aggregate Intrinsic Value | $	$ 97,600
Options Outstanding Exercise Price Range 3 [Member]
Upper Range of Exercise Price (in dollars per share)	$ 19.99
Number Outstanding (in shares) | shares	30,000
Outstanding Weighted Average Contractual Life Remaining (Year)	5 years 3 months 18 days
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 19.99
Outstanding Aggregate Intrinsic Value | $	$ 300
Options Outstanding Exercise Price Range 4 [Member]
Upper Range of Exercise Price (in dollars per share)	$ 39.11
Number Outstanding (in shares) | shares	8,000
Outstanding Weighted Average Contractual Life Remaining (Year)	5 years 8 months 12 days
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 39.11