Note 5 - Stock-based Compensation - Stock Options Outstanding and Exercisable (Details)	3 Months Ended
Mar. 31, 2024 USD ($) $ / shares shares
Share-Based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	$ 3.5
Share-Based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 39.11
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number \| shares	59,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	4 years 4 months 24 days
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 17.35
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value \| $	$ 120,910
Options Outstanding Exercise Price Range1 [Member]
Share-Based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	$ 3.5
Share-Based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 3.86
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number \| shares	13,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	3 years
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 3.75
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value \| $	$ 94,910
Options Outstanding Exercise Price Range2 [Member]
Share-Based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 7.8
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number \| shares	8,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	4 years 2 months 12 days
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 7.8
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value \| $	$ 26,000
Options Outstanding Exercise Price Range 3 [Member]
Share-Based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 19.99
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number \| shares	30,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	4 years 9 months 18 days
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 19.99
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value \| $	$ 0
Options Outstanding Exercise Price Range 4 [Member]
Share-Based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 39.11
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number \| shares	8,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	5 years 2 months 12 days
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 39.11
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value \| $	$ 0

Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

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Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
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-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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