Note 4 - Stock-based Compensation - Summary of Stock Option Activity (Details) - USD ($) |
3 Months Ended | 12 Months Ended |
|---|---|---|
Mar. 31, 2021 |
Dec. 31, 2020 |
|
| Outstanding at beginning of period (in shares) | 549,970 | |
| Outstanding at beginning of period, weighted average exercise price (in dollars per share) | $ 8.81 | |
| Outstanding, weighted average remaining contractual life (Year) | 8 years 146 days | 8 years |
| Outstanding, aggregate intrinsic value | $ 184,320 | $ 209,280 |
| Granted (in shares) | 229,500 | |
| Granted, weighted average exercise price (in dollars per share) | $ 2.54 | |
| Outstanding at end of period (in shares) | 779,470 | 549,970 |
| Outstanding at end of period, weighted average exercise price (in dollars per share) | $ 6.97 | $ 8.81 |
| Exercisable at end of period (in shares) | 201,438 | |
| Exercisable at end of period, weighted average exercise price (in dollars per share) | $ 15.21 | |
| Exercisable, weighted average remaining contractual life (Year) | 6 years 146 days | |
| Exercisable, aggregate intrinsic value | $ 67,841 |
| X | ||||||||||
- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Gross number of share options (or share units) granted during the period. No definition available.
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| X | ||||||||||
- Definition 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
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| X | ||||||||||
- Definition Number of options outstanding, including both vested and non-vested options. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options. No definition available.
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| X | ||||||||||
- Definition Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition 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. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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