Segment Disclosures (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011
Segment Reporting [Abstract]
Revenues from former exploration and production business now shown as external	$ 310
Costs attributable to former exploration and production business now shown as external	$ 845

For a disposal group that is a component of the entity (discontinued operation), in the period in which the operations are initially classified as discontinued, the amounts of intercompany revenue that were previously eliminated in consolidation for periods before the disposal transaction (in situations where revenue and cost producing activities with the disposed component will continue after disposal).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1518-107760

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