Commitments and Contingencies (Details) (USD $) In Millions | 9 Months Ended | |
|---|---|---|
Sep. 30, 2011 | Dec. 31, 2010 | |
| Beginning of period | $ 753 | |
| Accruals for environmental matters deemed probable and reasonably estimable | 177 | |
| Environmental liability payments | (156) | |
| Other | 3 | |
| End of period | 777 | |
| Loss Contingency Classification of Accrual [Abstract] | ||
| Accrued Liabilites | 306 | 328 |
| Other liabilities | 471 | 425 |
| Total environmental liabilities | $ 777 |