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Note 10 - Share-based Compensation - Fair Value Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Payment Arrangement, Option [Member]
Fair value of ordinary share (in dollars per share)			$ 13.96
Expected volatility			70.00%
Expected dividend yield	0.00%	0.00%	0.00%
Contractual life (years) (Year)	10 years	10 years	10 years
Share-based Payment Arrangement, Option [Member] | Minimum [Member]
Fair value of ordinary share (in dollars per share)	$ 9.48	$ 10.37
Risk-free interest rate	0.37%	0.11%	1.62%
Expected term (years) (Year)	5 years	5 years	5 years
Expected volatility	75.00%	70.00%
Share-based Payment Arrangement, Option [Member] | Maximum [Member]
Fair value of ordinary share (in dollars per share)	$ 31.31	$ 17.94
Risk-free interest rate	1.47%	1.64%	1.68%
Expected term (years) (Year)	7 years 5 months 26 days	10 years	7 years 1 month 6 days
Expected volatility	90.00%	75.00%
Options Granted in May 2021 [Member]
Fair value of ordinary share (in dollars per share)	$ 10.71
Risk-free interest rate	1.63%
Expected term (years) (Year)	10 years
Expected volatility	75.00%
Expected dividend yield	0.00%
Exercise price (in dollars per share)	$ 10.18

X

- Definition

Agreed-upon price for the exchange of the underlying asset relating to the share-based payment award.

+ References

No definition available.

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- 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.

+ 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)(iii)
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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.

+ References

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

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

+ References

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

Price of a single share of a number of saleable stocks of a company.

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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 718
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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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
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-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=122041274&loc=d3e301413-122809

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