Note 8 - Fair Value Measurements (Details Textual) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Fair Value Measurements [Line Items]
Percentage of equity investment acquired	19.90%
Fair value of the Company’s shares increased	$ 5,146	$ 5,146
Initial Public Offering
Fair Value Measurements [Line Items]
Percentage of equity investment acquired	16.30%