Note 11 - Warrant Liability - The Key Assumptions Used to Value the Warrants (Details)	Dec. 31, 2019	Aug. 13, 2019	Dec. 31, 2018
Measurement Input, Price Volatility [Member] | The 2011 Warrants [Member]
Warrants assumptions	1.15		0.77
Measurement Input, Price Volatility [Member] | The 2019 Ladenburg Warrants [Member]
Warrants assumptions	1.5994	1.5519
Measurement Input, Price Volatility [Member] | October 2015 Warrants [Member]
Warrants assumptions	1.84		0.73
Measurement Input, Price Volatility [Member] | The 2019 Domestic Warrants [Member]
Warrants assumptions	1.541	1.4929
Measurement Input, Price Volatility [Member] | Short-term Warrants [Member]
Warrants assumptions			0.77
Measurement Input, Price Volatility [Member] | Long-term Warrants [Member]
Warrants assumptions			0.77
Measurement Input, Price Volatility [Member] | The 2019 Foreign Warrants [Member]
Warrants assumptions	1.541	1.4929
Measurement Input, Expected Term [Member] | The 2011 Warrants [Member]
Warrants assumptions	0.18		1.18
Measurement Input, Expected Term [Member] | The 2019 Ladenburg Warrants [Member]
Warrants assumptions	4.61	5
Measurement Input, Expected Term [Member] | October 2015 Warrants [Member]
Warrants assumptions	0.83		1.83
Measurement Input, Expected Term [Member] | The 2019 Domestic Warrants [Member]
Warrants assumptions	5.13	5.5
Measurement Input, Expected Term [Member] | Short-term Warrants [Member]
Warrants assumptions			1.18
Measurement Input, Expected Term [Member] | Long-term Warrants [Member]
Warrants assumptions			1.18
Measurement Input, Expected Term [Member] | The 2019 Foreign Warrants [Member]
Warrants assumptions	5.13	5.5
Measurement Input, Risk Free Interest Rate [Member] | The 2011 Warrants [Member]
Warrants assumptions	0.0152		0.026
Measurement Input, Risk Free Interest Rate [Member] | The 2019 Ladenburg Warrants [Member]
Warrants assumptions	0.0169	0.0157
Measurement Input, Risk Free Interest Rate [Member] | October 2015 Warrants [Member]
Warrants assumptions	0.0159		0.0251
Measurement Input, Risk Free Interest Rate [Member] | The 2019 Domestic Warrants [Member]
Warrants assumptions	0.017	0.0158
Measurement Input, Risk Free Interest Rate [Member] | Short-term Warrants [Member]
Warrants assumptions			0.026
Measurement Input, Risk Free Interest Rate [Member] | Long-term Warrants [Member]
Warrants assumptions			0.026
Measurement Input, Risk Free Interest Rate [Member] | The 2019 Foreign Warrants [Member]
Warrants assumptions	0.017	0.0158
Measurement Input, Expected Dividend Rate [Member] | The 2011 Warrants [Member]
Warrants assumptions	0		0
Measurement Input, Expected Dividend Rate [Member] | The 2019 Ladenburg Warrants [Member]
Warrants assumptions	0	0
Measurement Input, Expected Dividend Rate [Member] | October 2015 Warrants [Member]
Warrants assumptions	0		0
Measurement Input, Expected Dividend Rate [Member] | The 2019 Domestic Warrants [Member]
Warrants assumptions	0	0
Measurement Input, Expected Dividend Rate [Member] | Short-term Warrants [Member]
Warrants assumptions			0
Measurement Input, Expected Dividend Rate [Member] | Long-term Warrants [Member]
Warrants assumptions			0
Measurement Input, Expected Dividend Rate [Member] | The 2019 Foreign Warrants [Member]
Warrants assumptions	0	0
Measurement Input, Share Price [Member] | The 2011 Warrants [Member]
Warrants assumptions	0.0044		0.0029
Measurement Input, Share Price [Member] | The 2019 Ladenburg Warrants [Member]
Warrants assumptions	0.0057	0.0074
Measurement Input, Share Price [Member] | October 2015 Warrants [Member]
Warrants assumptions	0.0049		0.0038
Measurement Input, Share Price [Member] | The 2019 Domestic Warrants [Member]
Warrants assumptions	0.0057	0.0075
Measurement Input, Share Price [Member] | Short-term Warrants [Member]
Warrants assumptions			0.0024
Measurement Input, Share Price [Member] | Long-term Warrants [Member]
Warrants assumptions			0.0029
Measurement Input, Share Price [Member] | The 2019 Foreign Warrants [Member]
Warrants assumptions	0.0057	0.0075