Commitments and Contingencies, Environmental Liabilities (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of year	$ 108	$ 106
Additions, Net	11	37
Expenditures	(26)	(35)
Balance at end of year	93	108
Cost-share agreement percentage responsible	.75
Environmental accrual under cost-share agreement	46
Martinez Refinery [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Accruals for environmental expenditures	55	62
Environmental insurance coverage ceiling	190
Self insurance deductible	$ 50
Number of previous owners	2

maximum amount covered by insurance policy

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number of previous owners

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only expenditures in excess of this amount will be covered under insurance policy

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Total costs accrued as of the balance sheet date for environmental loss contingencies.

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The aggregate amount disbursed during the reporting period to settle environmental loss contingencies.

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The amount added to the accrual for newly incurred environmental loss contingencies. These additions include remediation expense and interest accretion. These additions do not relate to changes in the environmental accrual related to a business acquisition or divestiture, to currency movements, or revisions in previously existing estimates.

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Carrying amount as of the balance sheet date of the liability for remediation, site restoration, postclosure, monitoring commitments, or other exit costs associated with the sale, disposal or abandonment of a particular property resulting from unanticipated contamination of the assets.

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Estimated undiscounted amount of the accrual for the environmental loss contingencies at an individual site as of the balance sheet date.

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

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