Derivatives (Effect Of Derivative Instruments Recognized In Statement Of Operations, Not Designated As Hedging Instruments) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2015		Jun. 30, 2014		Jun. 30, 2015		Jun. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Cash (payments) receipts on derivatives settled	$ 10,100		$ (9,100)		$ 21,082		$ (17,955)
Gain (loss) on derivatives not designated as hedges	(1,919)		(10,709)		4,667		(29,075)
Not Designated as Hedging Instrument [Member] | Commodity Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives not designated as hedges	(1,919)		(10,709)		4,667		(29,075)
Gain (Loss) on Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member] | Commodity Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives not designated as hedges	$ (1,919)	[1]	$ (10,709)	[1]	$ 4,667	[2]	$ (29,075)	[2]

[1] Amounts settled during the 2015 and 2014 periods include a gain of $10.1 million and a loss of $9.1 million, respectively.

[2] (1)Amounts settled during the 2015 and 2014 periods include a gain of $21.1 million and a loss of $18.0 million, respectively.