Energy Services Accounts Receivable Securitization Facility (Details) (USD $) In Millions	9 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Energy services accounts receivable securitization facility (Textuals) [Abstract]
Outstanding balance of trade receivables sold	$ 0
Energy Services Accounts Receivable Securitization Facility Additional Textuals [Abstract]
Receivables facility	200
Energy Services Funding Corporation [Member]
Energy services accounts receivable securitization facility (Textuals) [Abstract]
Sale of undivided interests in its trade receivables to the commercial paper conduit	68.0	233.6
Outstanding balance of trade receivables	50.9	61.8
Outstanding balance of trade receivables sold	0
Energy Services [Member]
Energy services accounts receivable securitization facility (Textuals) [Abstract]
Sale of trade receivables	$ 923.5	$ 933.3