Derivative Financial Instruments (Derivatives And Hedging-Overall-Subsequent Measurement) (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (30,074)	$ 13,030	$ (41,393)	$ 42,947
Commodity Contract [Member] | Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(38,411)	14,214	(45,786)	42,894
Commodity Contract [Member] | Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 8,337	$ (1,184)	$ 4,393	$ 53