Note 4 - Stock-based Compensation - Stock Options Outstanding and Exercisable (Details)	3 Months Ended
	Mar. 31, 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)	5 years 4 months 24 days
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 17.35
Outstanding Aggregate Intrinsic Value | $	$ 825,790
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)	4 years
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 3.75
Outstanding Aggregate Intrinsic Value | $	$ 342,950
Options Outstanding Exercise Price Range2 [Member]
Number Outstanding (in shares) | shares	8,000
Outstanding Weighted Average Contractual Life Remaining (Year)	5 years 2 months 12 days
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 7.80
Outstanding Aggregate Intrinsic Value | $	$ 178,640
Options Outstanding Exercise Price Range 3 [Member]
Number Outstanding (in shares) | shares	30,000
Outstanding Weighted Average Contractual Life Remaining (Year)	5 years 9 months 18 days
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 19.99
Outstanding Aggregate Intrinsic Value | $	$ 304,200
Options Outstanding Exercise Price Range 4 [Member]
Number Outstanding (in shares) | shares	8,000
Outstanding Weighted Average Contractual Life Remaining (Year)	6 years 2 months 12 days
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 39.11