Property, Plant and Equipment (Components of Property, Plant and Equipment) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	$ 13,564	$ 13,618
Pipeline Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	6,671	6,749
Offshore Drilling Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	3,920	4,119
Natural Gas And Oil Proved And Unproved Properties [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	965	1,330
Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	973	799
Construction In Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	$ 1,035	$ 621