Property Acquisitions and Divestitures (Details) (USD $)	12 Months Ended
	Dec. 31, 2009	Dec. 31, 2011	Dec. 31, 2010
Notes To Financial Statements [Abstract]
Estimated Proceeds from Sales of Producing Properties and Acreage on Certain Midstream Assets		$ 1,400,000,000
Proceeds received on sale of Canadian shallow gas assets			344,000,000
Impairment recorded to adjust Canadian shallow gas assets to fair value, less cost to sell			280,000,000
Aggregate proceeds received on sales non-core producing properties and acreage			673,000,000
Interest in planned liquefied natural gas plant (in hundredths)			49.00%
Percentage of planned natural gas pipeline owned by operator (in hundredths)			51.00%
Percentage of planned LNG export terminal owned by operator (in hundredths)			25.50%
Purchase price to acquire common stock of Galveston LNG			210,000,000
Additional interest acquired in planned natural gas pipeline (in hundredths)			24.50%
Purchase price to acquire additional interest in planned natural gas pipeline		25,200,000
Portion of purchase price to acquire additional interest in planned natural gas pipeline paid at closing		15,300,000
Interest in planned natural gas pipeline after acquisition of additional ownership interest in first quarter of 2011 (in hundredths)		24.50%
Pretax gain realized on a natural gas property exchange	390,000,000
Consideration received for sale of California crude oil and natural gas related assets	202,000,000
Pretax gain recognized from sale of California assets	146,000,000
Haynesville asset acquisition total consideration recorded	134,000,000		18,000,000
Barnett Shale Combo Aggregate Purchase Price	197,000,000
Barnett Shale Combo cash consideration paid	107,000,000
Shares exchanged for Barnett Shale Combo purchase	1,450,000
Common stock exchanged for Barnett Shale Combo purchase on the closing date	$ 89,600,000
Operator Ownership Interest in Proposed LNG Terminal and Pipeline Project Subsequent to Sell-Down		40.00%
Company's Interest in Propesed LNG Terminal and Pipeline Subsequent to Sell-down		30.00%
Interest in LNG Terminal and Pipeline Project Acquired by Third-party-in Sell-down Transactions		30.00%