Note 12 - Subsequent Events (Details Textual) - shares	1 Months Ended	6 Months Ended
	Jul. 31, 2018	Jun. 30, 2018	Jun. 30, 2017
Conversion of Stock, Shares Converted		795	58
Subsequent Event [Member] | Conversion From Series D Convertible Preferred Stock To Common Stock [Member]
Stock Issued During Period, Shares, New Issues	5,000,000
Conversion of Stock, Shares Converted	75