Exploratory Costs (Capitalized Exploratory Well And Project Activity) (Details) (USD $) In Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2011	Dec. 31, 2010
Beginning capitalized exploratory costs	$ 80,530	$ 96,193
Additions to exploratory costs pending the determination of proved reserves	140,081	214,345
Reclassification due to determination of proved reserves	(135,338)	(195,682)
Disposition of assets sold		(28,938)
Exploratory well costs charged to exploration expense	(162)	(807)
Ending capitalized exploratory costs	85,111	85,111
Suspended well costs recorded	7,982	7,982	25,558
Etzler Gas [Member]
Suspended well costs recorded	$ 8,000	$ 8,000