Note 17 - Loss Per Common Share (Details Textual) - $ / shares	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Share-based Payment Arrangement, Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	18,191,859	27,531,332
Share-based Payment Arrangement, Option [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance (in dollars per share)	$ 0.07
Share-based Payment Arrangement, Option [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance (in dollars per share)	$ 0.38
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	10,066,809	10,066,809
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 0.07
Warrant [Member] \| Minimum [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		0.07
Warrant [Member] \| Maximum [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 0.38

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

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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 (c)(1)(i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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