Note 14 - Stock Based Compensation - Valuation Assumptions (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Expected term (in years) (Year)	10 years
Employee Stock Option [Member] | Minimum [Member]
Risk free interest rate	2.47%	1.86%
Expected term (in years) (Year)	5 years 87 days	5 years 116 days
Expected volatility	108.81%	112.86%
Employee Stock Option [Member] | Maximum [Member]
Risk free interest rate	2.71%	2.04%
Expected term (in years) (Year)	5 years 208 days	6 years 131 days
Expected volatility	126.43%	114.19%