Derivatives (Schedule Of Effect On Operating Results) (Details) - Total Commodity Derivatives [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income, Supply & Logistics Product Costs	$ 7,379	$ (890)
Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income, Supply & Logistics Product Costs	6,286	(553)
Not Designated As Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income, Supply & Logistics Product Costs	$ 1,093	$ (337)