Note 12 - Summary of Stock Options - Valuation Assumptions for Stock Options (Details) |
3 Months Ended | 6 Months Ended | |
|---|---|---|---|
Jun. 30, 2021 |
Jun. 30, 2021 |
Jun. 30, 2020 |
|
| Expected term (Year) | 6 years | 6 years | 5 years |
| Average volatility | 83.00% | 83.00% | 73.00% |
| Risk-free interest rate | 0.98% | 0.98% | 0.45% |
| Dividend yield | 0.00% | 0.00% | 0.00% |
| X | ||||||||||
- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Rate of weighted-average expected volatility for award under share-based payment arrangement. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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