Note 5 - Stock Split (Details Textual) - $ / shares	Jul. 07, 2017	Jun. 30, 2018	Dec. 31, 2017	Apr. 30, 2015
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01	$ 0.01	$ 0.01
Stock Issued During Period, Percentage of Shares, Stock Split	66.67%
Stock Split from [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	5
Stock Split To [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	3