Note 11 - Preferred Stock and Common Stock (Details Textual) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	6 Months Ended
	Feb. 28, 2015	Jun. 30, 2016	Dec. 31, 2015
ATM Program [Member]
Common Stock, Par or Stated Value Per Share	$ 0.01
Maximum Aggregate Sales Price	$ 500.0
Stock Issued During Period, Shares, New Issues		4,961,395
Proceeds from Issuance of Common Stock		$ 138.5
Payments of Stock Issuance Costs		$ 1.4
Common Stock, Par or Stated Value Per Share		$ 0.01	$ 0.01