Landfill and Environmental Remediation Liabilities (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010	Dec. 31, 2009
Liabilities for landfill and environmental remediation costs
Current (in accrued liabilities)	$ 150	$ 148
Long-term	1,447	1,402
Total	1,597	1,550
Landfill Liabilities [Member]
Liabilities for landfill and environmental remediation costs
Current (in accrued liabilities)	105	105
Long-term	1,207	1,161
Total	1,312	1,266	1,267
Environmental Remediation Liabilities [Member]
Liabilities for landfill and environmental remediation costs
Current (in accrued liabilities)	45	43
Long-term	240	241
Total	$ 285	$ 284