Derivatives (Effect Of Derivative Instruments Recognized In Statement Of Income, Not Designated As Hedging Instruments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedges Loss Amount Settled During Period	$ (8,872)		$ (5,615)
Amount of Loss Recognized in Income on Derivative	(18,366)		(4,575)
Commodity Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Loss Recognized in Income on Derivative	$ (18,366)	[1]	$ (4,575)	[1]

[1] Amount settled during the period are losses of $(8.9) million and $(5.6) million, respectively.