Note 12 - Subsequent Events (Details Textual) - USD ($)	1 Months Ended	2 Months Ended	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 21, 2018
Proceeds from Convertible Debt			$ 1,329,000	$ 3,059,000
The 2018 Notes [Member]
Proceeds from Convertible Debt			1,300,000
Class of Warrant or Right, Principal Amount of Every Amount Of Notes Purchased			$ 3.50
Warrants in Connection with Securities Purchase Agreement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights					1,243,498
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 5
Subsequent Event [Member]
Proceeds from Convertible Debt	$ 800,000	$ 2,200,000
Subsequent Event [Member] | The 2018 Notes [Member]
Debt Instrument, Convertible, Conversion Price	$ 3.50	$ 3.50
Class of Warrant or Right, Principal Amount of Every Amount Of Notes Purchased	$ 3.50	$ 3.50
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4.50	$ 4.50
Subsequent Event [Member] | Warrants in Connection with Securities Purchase Agreement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	481,422	481,422
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right	2	2
Warrants and Rights Outstanding, Term	5 years	5 years