Note 6 - Derivative Obligations (Details Textual) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Jun. 30, 2016
Class of Warrant or Right, Outstanding	5,133,541		4,828,723
Derivative, Gain (Loss) on Derivative, Net, Total	$ 259,000	$ 69,000
Series A Warrant [Member]
Class of Warrant or Right, Outstanding				404,412