Note 6 - Embedded Derivatives and Derivative Warrant Liabilities - Schedule of Inputs to Lattice Model Used to Value Embedded Derivatives (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2018 $ / shares shares	Dec. 31, 2017 $ / shares shares	[1]
Stock price (in dollars per share)	$ 0.46	$ 0.59
Conversion Rate per $1,000 (in shares) | shares	1,358.9	1,358.9
Conversion Price (in dollars per share)	$ 0.74	$ 0.74
Maturity date	Mar. 15, 2020	Mar. 15, 2020
Measurement Input, Risk Free Interest Rate [Member]
Risk-free interest rate	2.24	1.89
Measurement Input, Price Volatility [Member]
Risk-free interest rate	75	75
Measurement Input, Entity Credit Risk [Member]
Risk-free interest rate	28	28

[1] The June 20, 2017 inputs represent the initial valuation of the 2020 Notes Embedded Derivative instrument that arose due to the exchange of the 2017 Notes for the 2020 Notes.