Dispositions (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		1 Months Ended		1 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Apr. 30, 2013 DJ Basin [Member]	Jan. 31, 2013 Alaska EP [Member]	Feb. 28, 2013 Marcellus Shale [Member]	Feb. 28, 2013 Neptune Gas Plant [Member]	Jan. 31, 2012 GOM Pipelines [Member]
Dispositions Detail [Line Items]
Pretax gain/loss on sale			$ (115)	$ 46	$ (43)	$ 98	$ 166
Proceeds from Sale of Oil and Gas Property and Equipment	312	208		195		166	206
Proceeds from Sale of Oil and Gas Property and Equipment, Six Month Escrow	$ 50	$ 0		$ 50

The cash inflow to dispose of long-lived, physical assets and mineral interests in oil and gas properties used for normal oil and gas operations.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 16

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 15

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3179-108585

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Data Type:	xbrli:monetaryItemType
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