Note 14 - Stock Based Compensation - Valuation Assumptions (Details) - $ / shares		12 Months Ended
Jan. 13, 2019	Dec. 31, 2019	Dec. 31, 2018
Dividend yield		0.00%
Share-based Payment Arrangement, Option [Member]
Dividend yield		0.00%	0.00%
Share-based Payment Arrangement, Option [Member] \| Minimum [Member]
Risk free interest rate		2.16%	2.47%
Expected term (in years) (Year)		5 years	5 years 87 days
Expected volatility		106.88%	108.81%
Share-based Payment Arrangement, Option [Member] \| Maximum [Member]
Risk free interest rate		2.20%	2.71%
Expected term (in years) (Year)		5 years 343 days	5 years 208 days
Expected volatility		126.16%	126.43%
Liability Options [Member]
Risk free interest rate	2.53%
Dividend yield
Stock price (in dollars per share)	$ 1.36
Liability Options [Member] \| Minimum [Member]
Expected term (in years) (Year)	4 years 182 days
Expected volatility	121.00%
Liability Options [Member] \| Maximum [Member]
Expected term (in years) (Year)	5 years
Expected volatility	123.00%

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.

+ References

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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

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

+ References

No definition available.

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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=116856206&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=115993241&loc=d3e301413-122809

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