Net Gains (Losses) on Sales of Fixed Assets Net Gains (Losses) on Sales of Fixed Assets Table (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Property, Plant and Equipment [Line Items]
Net (gains) losses on sales of fixed assets	$ (132)	$ 7	$ (290)	$ 5
Gas Gathering and Processing Equipment [Member]
Property, Plant and Equipment [Line Items]
Net (gains) losses on sales of fixed assets	(132)	(7)	(311)	(8)
Exploration and Production Equipment [Member]
Property, Plant and Equipment [Line Items]
Net (gains) losses on sales of fixed assets	0	10	1	12
Land and Building [Member]
Property, Plant and Equipment [Line Items]
Net (gains) losses on sales of fixed assets	1	0	24	0
Other Assets
Property, Plant and Equipment [Line Items]
Net (gains) losses on sales of fixed assets	$ (1)	$ 4	$ (4)	$ 1