Note 6 - Employee and Director Benefits - Assumption Used to Estimate Fair Value of Stock Option Awards (Details) - Employee Stock Option [Member] |
9 Months Ended | |
|---|---|---|
Sep. 30, 2017 |
Sep. 30, 2016 |
|
| Expected volatility | 29.00% | 29.00% |
| Expected dividends | 0.44% | 0.64% |
| Expected term (in years) (Year) | 6 years 91 days | 6 years 91 days |
| Risk-free rate | 2.08% | 1.86% |
| 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://www.xbrl.org/2003/role/presentationRef
|
| 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://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- 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://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Details
|