Commitments and Contingencies, Environmental Liabilities (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2012	Dec. 31, 2011
Environmental Exit Cost
Accruals for environmental expenditures	$ 91	$ 93
Cost-share arrangement percentage responsible	.75
Martinez refinery
Environmental Exit Cost
Accruals for environmental expenditures	55	55
Environmental accrual cost-share arrangment	45
Environmental insurance coverage ceiling	190
Self insurance deductible	$ 50
Number of previous owners (owners)	2

Nature and terms of cost-sharing arrangements with other potentially responsible parties for an individual site.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 30

-Section 50

-Paragraph 10

-Subparagraph (d)(3)

-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13237-110859

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 5.Y.Q2)

-URI http://asc.fasb.org/extlink&oid=6572457&loc=d3e149879-122751

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 5

-Section Y

-Paragraph Question 2

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 96-1

-Paragraph 163

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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