Derivatives And Fair Value Measurements (Carrying Value Of Derivatives) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012		Sep. 30, 2013	Sep. 30, 2012
Derivatives, Fair Value [Line Items]
Settlements in production revenue	$ (11,139)	$ (34,145)	[1]	$ (37,181)	$ (99,726)	[1]
Cash Flow Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative fair value at beginning of period		176,726			342,799
Ineffectiveness reported in net derivative gains		(547)			1,022
Unrealized gains (losses) reported in OCI		(15,543)			93,103
Derecognition of hedges					(180,732)
Derivative fair value at end of period		114,955			114,955
Production Revenue [Member] | Cash Flow Derivatives [Member]
Derivatives, Fair Value [Line Items]
Settlements in production revenue		(45,681)			137,417
Derivative gains (losses) [Member] | Cash Flow Derivatives [Member]
Derivatives, Fair Value [Line Items]
Settlements in net derivative (gains) losses					$ 3,820

[1] Note 1 contains additional information