Note 11 - Stock-based Compensation - Stock Option Valuation Assumptions (Details) - $ / shares	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020
Total stock options granted (in shares)	4,670,324	0
Weighted-average exercise price (in dollars per share)	$ 4.98
Weighted-average expected term (Year)	5 years 9 months
Weighted average volatility	144.00%
Weighted-average risk-free interest rate	0.87%
Expected dividends	0.00%
Weighted-average grant date fair value (in dollars per share)	$ 4.57

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

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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.

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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

Rate of weighted-average expected volatility for award under share-based payment arrangement.

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- Definition

Gross number of share options (or share units) granted during the period.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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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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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)
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