Note 15 - Income Taxes (Details Textual) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Schedule of Income Taxes [Line Items]
Operating loss carryforwards limitations minimum ownership change percentage	50.00%		50.00%
Operating loss carryforwards limitations ownership change period			3 years
Tax asset protection plan limiting transfer of common stock affecting ownership percentage			10.00%
Protective amendment limiting transfer of common stock affecting ownership percentage			10.00%
U.S. corporate income tax rate	21.00%	21.00%	21.00%	21.00%
Minimum [Member]
Schedule of Income Taxes [Line Items]
Tax asset protection plan limiting transfer of common stock additional shares acquired	1,000,000		1,000,000
Protective amendment limiting transfer of common stock additional shares acquired	1,000,000		1,000,000