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