Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Cash and cash equivalents attributable to VIEs	$ 438	$ 351
Accounts receivable	2,596	2,505
Evaluated natural gas and oil properties attributable to VIEs	43,589	41,723
Natural gas gathering systems and treating plants ($48 and $0 attributable to our VIEs)	2,034	1,763
Less: accumulated depreciation, depletion and amortization attributable to VIEs	(28,888)	(28,290)
Short-term derivative liabilities attributable to VIEs	253	191
Other current liabilities attributable to VIEs	3,420	3,397
Long-term derivative liabilities attributable to VIEs	1,605	1,541
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares outstanding	7,251,515	7,251,515
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	664,181,137	660,888,159
Treasury stock, shares	1,682,354	1,552,533
Variable Interest Entities [Member]
Cash and cash equivalents attributable to VIEs	47	1
Accounts receivable	11	0
Evaluated natural gas and oil properties attributable to VIEs	488	498
Natural gas gathering systems and treating plants ($48 and $0 attributable to our VIEs)	48	0
Less: accumulated depreciation, depletion and amortization attributable to VIEs	(18)	(6)
Short-term derivative liabilities attributable to VIEs	13	9
Other current liabilities attributable to VIEs	37	23
Long-term derivative liabilities attributable to VIEs	$ 19	$ 10