Energy Services Accounts Receivable Securitization Facility (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Energy services accounts receivable securitization facility (Textual) [Abstract]
Receivables facility	$ 0
Energy Services [Member]
Energy services accounts receivable securitization facility (Textual) [Abstract]
Sale of trade receivables	524.3	510.8
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	179.0	209.5
Outstanding balance of trade receivables	82.6	59.8
Outstanding balance of trade receivables sold	11.0	27.0
Former receivables facility capacity [Member]
Energy services accounts receivable securitization facility (Textual) [Abstract]
Receivables facility	$ 200