Derivatives (Effect Of Derivative Instruments Recognized In Statement Of Operations, Not Designated As Hedging Instruments) (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Cash receipts (payments) on derivatives settled	$ 11,100		$ (1,000)		$ 32,156		$ (18,984)
Gain (loss) on derivatives not designated as hedges	8,250		19,841		12,917		(9,234)
Not Designated as Hedging Instrument [Member] | Commodity Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives not designated as hedges	8,250		19,841		12,917		(9,234)
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	$ 8,250	[1]	$ 19,841	[1]	$ 12,917	[2]	$ (9,234)	[2]

[1] )Amounts settled during the 2015 and 2014 periods include a gain of $11.1 million and a loss of $1.0 million, respectivel

[2] Amounts settled during the 2015 and 2014 periods include a gain of $32.2 million and a loss of $19.0 million, respectively.