Note 5 - Stock-based Compensation - Fair Value of Stock-based Award on the Date of Grant (Details)	Jun. 15, 2020	May 12, 2020
May 2020 SARs [Member]
Risk-free interest rates		0.44%
Expected life (in years) (Year)		2 years 9 months 18 days
Dividend yield		0.63%
Expected volatility (weighted average)		28.14%
June 2020 SARs [Member]
Dividend yield	0.64%
June 2020 SARs [Member] \| Minimum [Member]
Risk-free interest rates	0.44%
Expected life (in years) (Year)	2 years
Expected volatility (weighted average)	28.50%
June 2020 SARs [Member] \| Maximum [Member]
Risk-free interest rates	0.28%
Expected life (in years) (Year)	2 years 9 months 18 days
Expected volatility (weighted average)	35.20%

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.

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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.

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

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- 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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

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