Energy Services Accounts Receivable Securitization Facility (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Energy services accounts receivable securitization facility (Additional Textual) [Abstract]
Receivables facility	$ 200
Energy Services Funding Corporation [Member]
Energy services accounts receivable securitization facility (Textual) [Abstract]
Sale of undivided interests in its trade receivables to the commercial paper conduit	209.5	68.0
Outstanding balance of trade receivables	59.8	86.7
Outstanding balance of trade receivables sold	27
Energy Services [Member]
Energy services accounts receivable securitization facility (Textual) [Abstract]
Sale of trade receivables	$ 510.8	$ 687.0