Note 4 - Stock-based Compensation - Assumptions (Details) |
3 Months Ended | 9 Months Ended | |
|---|---|---|---|
Sep. 30, 2018 |
Sep. 30, 2019 |
Sep. 30, 2018 |
|
| Risk-free interest rate | 2.75% | 2.31% | |
| Dividend yield | 0.00% | 0.00% | |
| Expected term (Year) | 5 years | 5 years | 5 years |
| Expected volatility | 53.40% | 57.90% | |
| Minimum [Member] | |||
| Risk-free interest rate | 2.65% | ||
| Expected volatility | 49.00% | ||
| Maximum [Member] | |||
| Risk-free interest rate | 2.92% | ||
| Expected volatility | 53.40% | ||
| 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
|