Note 11 - Subsequent Events (Details Textual)				3 Months Ended	12 Months Ended
	Jan. 24, 2020 USD ($) $ / shares shares	Jan. 21, 2020	Apr. 30, 2019	Mar. 23, 2020 shares	Dec. 31, 2019 shares	Dec. 31, 2018 shares
Conversion of Stock, Shares Issued					296,390	95
Conversion of Series H Preferred Stock Into Common Stock [Member]
Conversion of Stock, Shares Converted					1,570
Conversion of Stock, Shares Issued					296,160
Subsequent Event [Member] | Series J Convertible Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues	300
Proceeds from Issuance of Preferred Stock and Preference Stock | $	$ 300,000
Convertible Preferred Stock, Conversion Price1 | $ / shares	$ 2
Subsequent Event [Member] | Conversion of Series H Preferred Stock Into Common Stock [Member]
Conversion of Stock, Shares Converted				1,686
Subsequent Event [Member] | Conversion of Series I Preferred Stock Into Common Stock [Member]
Conversion of Stock, Shares Converted				700
Subsequent Event [Member] | Conversion of Series H and Series I Preferred Stock Into Common Stock [Member]
Conversion of Stock, Shares Issued				13,481,349
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio			500
Reverse Stock Split [Member] | Subsequent Event [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio		2,000