Properties and Equipment (Detail) (USD $)	Dec. 31, 2013		Dec. 31, 2012
Property, Plant, and Equipment [Line Items]
Cost of properties and equipment	$ 71,244,000,000		$ 63,598,000,000
Oil and Gas Exploration and Production Reporting Segment [Member]
Property, Plant, and Equipment [Line Items]
Cost of properties and equipment	61,302,000,000	[1]	55,180,000,000	[1]
Table Text Block Supplement [Abstract]
Costs associated with unproved properties	6,900,000,000		7,100,000,000
Midstream Reporting Segment [Member]
Property, Plant, and Equipment [Line Items]
Cost of properties and equipment	7,285,000,000		6,032,000,000
Marketing Reporting Segment [Member]
Property, Plant, and Equipment [Line Items]
Cost of properties and equipment	9,000,000		9,000,000
Other and Intersegment Eliminations [Member]
Property, Plant, and Equipment [Line Items]
Cost of properties and equipment	$ 2,648,000,000		$ 2,377,000,000

[1] Includes costs associated with unproved properties of $6.9 billion at December 31, 2013, and $7.1 billion at December 31, 2012.