Note 12 - Share-based Compensation - Stock Option Assumptions (Details) - $ / shares |
12 Months Ended | |
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Dec. 31, 2018 |
Dec. 31, 2017 |
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| Risk-free interest rate | 1.10% | |
| Expected dividend yield | 0.00% | 0.00% |
| Expected option life (Year) | 4 years 182 days | |
| Minimum [Member] | ||
| Common share fair value (in dollars per share) | $ 8.84 | $ 5.20 |
| Risk-free interest rate | 2.10% | |
| Expected option life (Year) | 4 years 292 days | |
| Expected stock price volatility | 123.50% | 84.70% |
| Maximum [Member] | ||
| Common share fair value (in dollars per share) | $ 9.33 | $ 8.40 |
| Risk-free interest rate | 2.20% | |
| Expected option life (Year) | 5 years | |
| Expected stock price volatility | 135.70% | 156.80% |
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- Definition Agreed-upon price for the exchange of the underlying asset relating to the share-based payment award. No definition available.
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- 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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- 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
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- 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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- Definition Expected term of share-based compensation awards, 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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