Note 2 - Equity Offerings (Details Textual) - USD ($) $ / shares in Units, shares in Millions		6 Months Ended
	Jan. 20, 2017	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Common Stock, Par or Stated Value Per Share		$ 0.01		$ 0.01
Proceeds from Issuance of Common Stock		$ 96,030,003
December Private Placement [Member]
Stock Issued During Period, Shares, New Issues	22.2
Common Stock, Par or Stated Value Per Share	$ 0.01
Shares Issued, Price Per Share	$ 4.50
Proceeds from Issuance of Common Stock, Gross	$ 100,000,000
Proceeds from Issuance of Common Stock	$ 96,000,000