Note 11 - Subsequent Event	12 Months Ended
Dec. 31, 2019
Notes to Financial Statements
Subsequent Events [Text Block]	11. Subsequent Event Through March 17, 2020, 1,124,071 warrants were exercised at $0.35 per warrant resulting in proceeds received of $0.4 million.

The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-URI http://asc.fasb.org/topic&trid=2122774

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