Revenue related to the upstream oil and gas activities, such as exploration, development, and production of crude petroleum.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 932

-SubTopic 235

-Section 50

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62246-109447

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 932

-SubTopic 605

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6475351&loc=d3e68354-109478

Name:	us-gaap_ExplorationAndProductionRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Segment Information Narrative (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
Segment Reporting Information [Line Items]
Number of reportable segments			3
Marketing, Gathering And Compression
Segment Reporting Information [Line Items]
Exploration and Production Revenue	$ (1,933)	$ (1,161)	$ (3,678)	$ (2,336)