Note 7 - Preferred Stock (Details Textual) - $ / shares	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2011
Preferred Stock, Shares Authorized	3,000,000
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock Number Of Authorized Shares Remaining	2,445,598	2,445,598
Preferred Stock, Shares Outstanding, Ending Balance	0	0
Preferred Stock, Shares Issued, Total	0	0
Series A Preferred Stock [Member]
Preferred Stock, Shares Authorized	3,000,000
Preferred Stock, Dividend Rate, Percentage	10.00%
Preferred Stock, Conversion Basis	1
Common Stock For Conversion			554,402
Preferred Stock Number Of Authorized Shares Remaining			2,445,598
Preferred Stock, Shares Outstanding, Ending Balance	0
Preferred Stock, Shares Issued, Total	0