Note 4 - Summary of Significant Accounting Policies - Calculation of Net Loss Per Common Share (Details) - USD ($)	12 Months Ended		84 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017
Net loss	$ (10,374,000)	$ (5,112,000)	$ (29,200,000)
Weighted average shares outstanding—basic and diluted (in shares)	3,566,098	3,106,846
Basic and diluted net loss per share (in dollars per share)	$ (2.91)	$ (1.65)