Note 6 - Long-term Debt and Lease Obligation - Carrying Amount of the Company's Outstanding Debt (Details) (Parentheticals)	Dec. 31, 2018	Dec. 31, 2017
Senior Secured Debt, Due March 25, 2021 [Member]
Debt instrument, interest rate, stated percentage	8.00%	8.00%
Convertible Note Instrument, Due March 5, 2018 [Member]
Debt instrument, interest rate, stated percentage		7.00%
Convertible Note Instrument, Due March 5, 2020 [Member]
Debt instrument, interest rate, stated percentage	7.00%	7.00%