Impairment of Fixed Assets and Other Table (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments of fixed assets and other	$ 231	$ 243	$ 258	$ 243
Natural Gas Gathering Systems And Treating Plants [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments of fixed assets and other	213	219	239	219
Drilling Rigs And Equipment [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments of fixed assets and other	4	24	4	24
Other Assets
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments of fixed assets and other	$ 14	$ 0	$ 15	$ 0