Note 13 - Subsequent Events (Details Textual) - USD ($)					1 Months Ended		2 Months Ended	12 Months Ended
	May 25, 2019	Feb. 26, 2019	Feb. 25, 2019	Feb. 18, 2019	Mar. 31, 2019	Mar. 31, 2018	Feb. 28, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Feb. 28, 2015
Preferred Stock, Par or Stated Value Per Share								$ 0.01	$ 0.01
Class of Warrant or Right, Exercise Price of Warrants or Rights								$ 0.03
Series C Convertible Preferred Stock [Member]
Conversion of Stock, Shares Converted								420	298	132
Conversion of Stock, Shares Issued								28,000,000	19,862,000	1,400,000
Preferred Stock, Par or Stated Value Per Share								$ 1,000	$ 1,000		$ 1,000
Convertible Preferred Stock, Conversion Price1									$ 0.015
Preferred Stock, Shares Outstanding, Ending Balance								2,150	2,570
Series E Convertible Preferred Stock [Member]
Conversion of Stock, Shares Converted						600
Preferred Stock, Par or Stated Value Per Share						$ 1,000		$ 1,000	$ 1,000
Convertible Preferred Stock, Conversion Price1								$ 0.02544
Preferred Stock, Shares Outstanding, Ending Balance								1,200	0
Subsequent Event [Member]
Number of Series C and Series E Preferred Stock Exchanged for Series F Convertible Preferred Stock				2,763
Subsequent Event [Member] | Term Notes [Member]
Debt Instrument, Face Amount, Canceled		$ 250,000
Subsequent Event [Member] | First Closing [Member] | Series I Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			16,666,666
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 0.015
Warrants and Rights Outstanding, Term			5 years
Subsequent Event [Member] | Second Closing [Member] | Series I Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			33,333,332
Subsequent Event [Member] | Third Closing [Member] | Series I Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			33,333,332
Subsequent Event [Member] | Series G Convertible Preferred Stock and Related Warrants [Member]
Convertible Preferred Stock and Related Warrants, Authorized	1,000
Proceeds from Issuance of Convertible Preferred Stock and Related Warrants, Maximum	$ 1,000,000
Convertible Preferred Stock and Related Warrants Issued		500
Subsequent Event [Member] | Series G Convertible Preferred Stock and Related Warrants [Member] | First Closing [Member]
Proceeds from Issuance of Convertible Preferred Stock and Related Warrants, Maximum		$ 250,000
Subsequent Event [Member] | Series G Convertible Preferred Stock and Related Warrants [Member] | Second Closing [Member]
Proceeds from Issuance of Convertible Preferred Stock and Related Warrants, Maximum			$ 250,000
Subsequent Event [Member] | Series G Convertible Preferred Stock and Related Warrants [Member] | Third Closing [Member]
Proceeds from Issuance of Convertible Preferred Stock and Related Warrants, Maximum			$ 250,000
Subsequent Event [Member] | Series F Convertible Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share				$ 1,000
Convertible Preferred Stock, Conversion Price1				$ 0.015
Convertible Preferred Stock, Conversion Price, Percentage of Volume Weighted Average Price of the Common Stock				90.00%
Subsequent Event [Member] | Series C Convertible Preferred Stock [Member]
Preferred Stock, Shares Outstanding, Ending Balance				0
Subsequent Event [Member] | Series G Convertible Preferred Stock [Member]
Convertible Preferred Stock, Conversion Price1			$ 0.015
Convertible Preferred Stock, Conversion Price, Percentage of Volume Weighted Average Price of the Common Stock			90.00%
Subsequent Event [Member] | Series E Convertible Preferred Stock [Member]
Preferred Stock, Shares Outstanding, Ending Balance				0
Conversion of Series C Preferred Stock Into Common Stock [Member] | Subsequent Event [Member]
Conversion of Stock, Shares Converted							587
Conversion of Stock, Shares Issued							39,140,000
Conversion of Series F Preferred Stock Into Common Stock [Member] | Subsequent Event [Member]
Conversion of Stock, Shares Converted					180
Conversion of Stock, Shares Issued					20,000,000