Note 15 - Stock-based Compensation - Fair Value of Stock-based Award Using Exercise Multiple-based Lattice SAR Pricing Model Assumptions (Details)		12 Months Ended
Nov. 07, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Risk-free interest rate		0.70%	0.40%	1.80%
Expected life (in years) (Year)		3 years 9 months 18 days	5 years 9 months 18 days	3 years 6 months
Expected volatility		36.70%	28.80%	25.10%
Director [Member] \| The 2018 Incentive Plan [Member] \| Stock Appreciation Rights (SARs) [Member]
Risk-free interest rate	1.79%
Expected volatility	24.80%
Director [Member] \| The 2018 Incentive Plan [Member] \| Stock Appreciation Rights (SARs) [Member] \| Minimum [Member]
Expected life (in years) (Year)	1 year
Director [Member] \| The 2018 Incentive Plan [Member] \| Stock Appreciation Rights (SARs) [Member] \| Maximum [Member]
Expected life (in years) (Year)	6 years

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=122041274&loc=d3e301413-122809

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