Asset Impairments (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Impaired Long-Lived Assets Held and Used [Line Items]
Total - Impairment of Oil and Gas Properties	$ 131,000	$ 0	$ 139,000	$ 0
East Texas [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Total - Impairment of Oil and Gas Properties	116,000	0	116,000	0
Other (Primarily Onshore US) [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Total - Impairment of Oil and Gas Properties	$ 15,000	$ 0	$ 23,000	$ 0