Derivatives (Gain Or Loss Of Reclassified Accumulated Other Comprehensive Income And Recognized In Income) (Details) (Commodity Derivatives [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain or (loss) reclassified from accumulated OCI into income	$ (3,210)		$ 14,243		$ (202)		$ 38,088
Derivative Instruments, Gain Recognized in Income	(252)		(4,015)		116		(4,621)
Oil and natural gas revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain or (loss) reclassified from accumulated OCI into income	(3,210)	[1]	14,243	[1]	(202)	[1]	38,088	[1]
Derivative Instruments, Gain Recognized in Income	0		0		0		0
Gain (loss) on derivatives not designated as hedges and hedge ineffectiveness, net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain or (loss) reclassified from accumulated OCI into income	0		0		0		0
Derivative Instruments, Gain Recognized in Income	$ (252)	[2]	$ (4,015)	[2]	$ 116	[2]	$ (4,621)	[2]

[1] Effective portion of gain (loss).

[2] Ineffective portion of gain (loss).