Note 5 - Summary of Significant Accounting Policies (Details Textual) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Percentage Of Income Tax Examination Likelihood Of Tax Benefits Being Realized Upon Settlement	50.00%
Unrecognized Tax Benefits, Ending Balance	$ 0
Preferred Stock, Dividend Rate, Percentage	10.00%
Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member]
Property, Plant and Equipment, Useful Life	7 years