Exploratory Costs (Schedule Of Capitalized Exploratory Well And Project Activity) (Details) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2014
Beginning capitalized exploratory costs	$ 310,000	$ 305,000		$ 305,000
Additions to exploratory costs pending the determination of proved reserves	235,000			461,000
Reclassification due to determination of proved reserves	(265,000)			(481,000)
Impairment of oil and gas properties	0		$ 0	138,000	$ 0
Exploratory well costs charged to exploration expense	(10,000)			(15,000)
Ending capitalized exploratory costs	$ 270,000	$ 310,000		$ 270,000
Number of projects with exploratory costs that have been suspended for a period greater than one year	0			0		0