Derivatives (Schedule Of Effect On Operating Results) (Details) - Total Commodity Derivatives [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income, Supply & Logistics Product Costs	$ 6,432	$ (12,543)	$ 13,811	$ (13,433)
Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income, Supply & Logistics Product Costs	5,546	(9,398)	11,832	(9,951)
Not Designated As Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income, Supply & Logistics Product Costs	$ 886	$ (3,145)	$ 1,979	$ (3,482)