Commitments and Contingencies (Details) (USD $) In Millions	Jun. 30, 2011	Sep. 30, 2010	Jun. 30, 2010
Commitments and Contingencies (Textuals)
Reserves for environmental costs	$ 42	$ 47	$ 38
Conditional asset retirement obligations	$ 95	$ 84	$ 81

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 143
-Paragraph 3, 10, 22

Name:	us-gaap_AssetRetirementObligation
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant