Note 10 - Stock Compensation Plans - Stock Options Outstanding and Exercisable (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
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)	59,000	126,500	126,000
Outstanding Weighted Average Contractual Life Remaining (Year)	6 years 7 months 6 days
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 17.35
Outstanding Aggregate Intrinsic Value	$ 1,267,960
Exercisable Options (in shares)	49,000
Weighted-Average Contractual Life Remaining - Exercisable (Year)	6 years 6 months
Weighted-Average Exercise Price - Exercisable (in dollars per share)	$ 16.81
Aggregate Intrinsic Value - Exercisable	$ 1,079,860
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)	13,000
Outstanding Weighted Average Contractual Life Remaining (Year)	6 years
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 3.75
Outstanding Aggregate Intrinsic Value	$ 528,960
Options Exercisable Exercise Price Range 1 [Member]
Lower Range of Exercise Price (in dollars per share)	$ 3.50
Upper Range of Exercise Price (in dollars per share)	$ 3.86
Exercisable Options (in shares)	13,000
Weighted-Average Contractual Life Remaining - Exercisable (Year)	5 years 2 months 12 days
Weighted-Average Exercise Price - Exercisable (in dollars per share)	$ 3.75
Aggregate Intrinsic Value - Exercisable	$ 528,960
Options Outstanding Exercise Price Range2 [Member]
Lower Range of Exercise Price (in dollars per share)	$ 7.80
Number Outstanding (in shares)	8,000
Outstanding Weighted Average Contractual Life Remaining (Year)	5 years 9 months 18 days
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 7.80
Outstanding Aggregate Intrinsic Value	$ 174,700
Options Exercisable Exercise Price Range 2 [Member]
Lower Range of Exercise Price (in dollars per share)	$ 7.80
Exercisable Options (in shares)	8,000
Weighted-Average Contractual Life Remaining - Exercisable (Year)	6 years 6 months
Weighted-Average Exercise Price - Exercisable (in dollars per share)	$ 7.80
Aggregate Intrinsic Value - Exercisable	$ 174,700
Options Outstanding Exercise Price Range 3 [Member]
Lower Range of Exercise Price (in dollars per share)	$ 19.99
Number Outstanding (in shares)	30,000
Outstanding Weighted Average Contractual Life Remaining (Year)	6 years 4 months 24 days
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 19.99
Outstanding Aggregate Intrinsic Value	$ 564,300
Options Exercisable Exercise Price Range3 [Member]
Lower Range of Exercise Price (in dollars per share)	$ 19.99
Exercisable Options (in shares)	20,000
Weighted-Average Contractual Life Remaining - Exercisable (Year)	6 years 6 months
Weighted-Average Exercise Price - Exercisable (in dollars per share)	$ 19.99
Aggregate Intrinsic Value - Exercisable	$ 376,200
Options Outstanding Exercise Price Range 4 [Member]
Lower Range of Exercise Price (in dollars per share)	$ 39.11
Number Outstanding (in shares)	8,000
Outstanding Weighted Average Contractual Life Remaining (Year)	7 years 4 months 24 days
Outstanding Weighted Average Exercise Price (in dollars per share)	$ 39.11
Outstanding Aggregate Intrinsic Value	$ 0
Options Exercisable Exercise Price Range 4 [Member]
Lower Range of Exercise Price (in dollars per share)	$ 39.11
Exercisable Options (in shares)	8,000
Weighted-Average Contractual Life Remaining - Exercisable (Year)	6 years 6 months
Weighted-Average Exercise Price - Exercisable (in dollars per share)	$ 39.11
Aggregate Intrinsic Value - Exercisable	$ 0