Derivative Instruments (GainLoss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Derivatives not designated as hedging contracts | Commodity swap contracts | Cost of sales
Derivative Instruments
Amount of Gain/(Loss) Recognized in Income on Derivatives	$ (601)	$ (1,254)	$ (736)	$ (1,119)
Derivatives not designated as hedging contracts | Interest rate swap contracts | Interest expense
Derivative Instruments
Amount of Gain/(Loss) Recognized in Income on Derivatives	$ (509)	(4)	(1,311)	(26)
Discontinued Operations. | Mid-Continent Business
Derivative Instruments
Amount of Gain/(Loss) Recognized in Income on Derivatives		$ (4,437)	$ 361	$ (3,801)