Note 2 - Summary of Significant Accounting Policies - Fair Value Derivative Assumptions (Details) - Warrant Liabilities [Member]	Mar. 31, 2018	Dec. 31, 2017
Measurement Input, Share Price [Member]
Fair value assumptions	0.67	0.65
Measurement Input, Expected Dividend Rate [Member]
Fair value assumptions
Measurement Input, Price Volatility [Member]
Fair value assumptions	0.9757	0.9374
Measurement Input, Risk Free Interest Rate [Member]
Fair value assumptions	0.0109	0.0166
Measurement Input, Expected Term in Days [Member]
Fair value assumptions	76
Measurement Input, Expected Term in Years [Member]
Fair value assumptions		0.5