Derivatives (Effect Of Derivative Instruments Recognized In Statement Of Income, Not Designated As Hedging Instruments) (Details) (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedges Gain (Loss) Amount Settled During Period	$ (9,100,000)		$ (200,000)		$ (18,000,000)		$ 900,000
Amount of Gain or (Loss) Recognized in Income on Derivative	(10,709,000)		14,627,000		(29,075,000)		10,052,000
Commodity Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ (10,709,000)	[1]	$ 14,627,000	[1]	$ (29,075,000)	[2]	$ 10,052,000	[2]

[1] Amounts settled during the 2014 and 2013 periods include losses of $(9.1) million and $(0.2) million, respectively.

[2] Amounts settled during the 2014 and 2013 periods include a loss of $(18.0) million and a gain of $0.9 million, respectively.