Other Liabilities (Details 2) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Non-ARO environmental liabilities
Environmental Loss
Accrual for environmental loss contingencies	$ 229	$ 262
ARO liabilities
Environmental Loss
Accrual for environmental loss contingencies	$ 171	$ 187

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

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

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

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