Note 6 - Stock-based Compensation - Stock Option Activity (Details) - USD ($) |
3 Months Ended | 9 Months Ended | ||||||
|---|---|---|---|---|---|---|---|---|
Sep. 30, 2021 |
Jun. 30, 2021 |
Mar. 31, 2021 |
Sep. 30, 2020 |
Jun. 30, 2020 |
Mar. 31, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
|
| Outstanding, shares (in shares) | 1,262,500 | 1,515,000 | 1,395,000 | 1,220,000 | 1,220,000 | 1,349,000 | 1,395,000 | 1,349,000 |
| Outstanding, weighted average exercise price (in dollars per share) | $ 0.86 | $ 0.53 | $ 0.31 | $ 0.24 | $ 0.24 | $ 0.23 | $ 0.31 | $ 0.23 |
| Options granted, shares (in shares) | 30,000 | 127,500 | 145,000 | 210,000 | 10,000 | 0 | 302,500 | 220,000 |
| Options granted, weighted average exercise price (in dollars per share) | $ 2.80 | $ 2.85 | $ 2.62 | $ 0.66 | $ 0.15 | |||
| Options exercised, shares (in shares) | (65,000) | (360,000) | (25,000) | 0 | (450,000) | 0 | ||
| Options exercised, weighted average exercise price (in dollars per share) | $ 0.18 | $ 0.22 | $ 0.14 | |||||
| Options expired, shares (in shares) | (20,000) | (10,000) | (129,000) | |||||
| Options expired (in dollars per share) | $ 0.17 | $ 0.19 | $ 0.17 | |||||
| Outstanding, shares (in shares) | 1,227,500 | 1,262,500 | 1,515,000 | 1,430,000 | 1,220,000 | 1,220,000 | 1,227,500 | 1,430,000 |
| Outstanding, weighted average exercise price (in dollars per share) | $ 0.94 | $ 0.86 | $ 0.53 | $ 0.30 | $ 0.24 | $ 0.24 | $ 0.94 | $ 0.30 |
| Outstanding, weighted average remaining contractual term (Month) | 61 months | 53 months | ||||||
| Outstanding, aggregate intrinsic value | $ 2,450,068 | $ 487,773 | $ 2,450,068 | $ 487,773 | ||||
| Exercisable, shares (in shares) | 930,000 | 1,208,500 | 930,000 | 1,208,500 | ||||
| Exercisable, weighted average exercise price (in dollars per share) | $ 0.44 | $ 0.24 | $ 0.44 | $ 0.24 | ||||
| Exercisable, weighted average remaining contractual term (Month) | 53 months | 41 months | ||||||
| Exercisable, aggregate intrinsic value | $ 2,326,943 | $ 482,268 | $ 2,326,943 | $ 482,268 | ||||
| X | ||||||||||
- Definition Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements. 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 Number of fully vested and expected to vest exercisable options that may be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Weighted average price at which option holders acquired shares when converting their stock options into shares. No definition available.
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| X | ||||||||||
- Definition Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired. No definition available.
|
| 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 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
|
| X | ||||||||||
- Definition Weighted average remaining contractual term for fully vested and expected to vest exercisable or convertible options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Number of share options (or share units) exercised during the current period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|