Note 12 - Share-based Compensation - Stock Option Assumptions (Details) - $ / shares |
12 Months Ended | |
|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| Expected dividend yield | 0.00% | 0.00% |
| Minimum [Member] | ||
| Common share fair value (in dollars per share) | $ 4.08 | $ 2.07 |
| Risk-free interest rate | 0.30% | 1.50% |
| Expected option life (years) (Year) | 5 years | 4 years 73 days |
| Expected stock price volatility | 94.40% | 88.70% |
| Maximum [Member] | ||
| Common share fair value (in dollars per share) | $ 6.91 | $ 4.60 |
| Risk-free interest rate | 1.30% | 2.40% |
| Expected option life (years) (Year) | 5 years 73 days | 5 years 36 days |
| Expected stock price volatility | 102.20% | 103.50% |
| X | ||||||||||
- Definition Agreed-upon price for the exchange of the underlying asset relating to the share-based payment award. No definition available.
|
| 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
|
| X | ||||||||||
- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| 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
|
| 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
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|