Note 9 - Common Stock (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Common Stock, Shares Authorized	300,000,000
Common Stock, Par or Stated Value Per Share	$ 0.001
Dividends, Common Stock, Total	$ 0	$ 0
Common Class A [Member]
Common Stock, Shares Authorized	200,000,000	200,000,000
Common Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Common Stock, Shares, Issued, Total	95,943,408	95,943,408
Common Stock, Shares, Outstanding, Ending Balance	95,943,408	95,943,408
Common Class B [Member]
Common Stock, Shares Authorized	100,000,000	100,000,000
Common Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Common Stock, Shares, Issued, Total	0	0
Common Stock, Shares, Outstanding, Ending Balance	0	0