Note 18 - Equity Incentive Plan - Schedule of Weighted-average Black-Scholes Fair Value Assumptions (Details)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Expected dividends	1.60%	1.22%	1.27%
Expected term (in years) (Year)	7 years 1 month 20 days	9 years 4 months 6 days	7 years 9 months 14 days
Expected stock price volatility	25.00%	24.00%	26.00%
Risk-free rate	1.90%	2.83%	2.23%

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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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.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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-Name Accounting Standards Codification
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