Note 6 - Warrants - Assumptions Used to Determine Fair Value of Warrants (Details)	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Risk free interest rate	0.23%	2.54%
Expected volatility	112.00%	252.00%
Expected life (Year)	2 years
Minimum [Member]
Risk free interest rate		2.18%
Expected volatility		86.00%
Expected life (Year)		2 years
Maximum [Member]
Risk free interest rate		2.62%
Expected volatility		110.00%
Expected life (Year)		5 years

Period an equity-based award is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

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- Definition

The estimated measure of the percentage amount by which a share price is expected to fluctuate during the expected term of a nonvested share or option award issued to other than an employee.

+ 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)(ii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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- Definition

The risk-free interest rate assumption that is used in valuing a nonvested share or option award issued to other than an employee.

+ 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)(iv)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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