Note 11 - Business Segments and Significant Customers (Details Textual) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Number of Reportable Segments	4
Derivative, Gain on Derivative	$ 14.2	$ 6.2	$ 1.5