Energy Services Accounts Receivable Securitization Facility (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		5 Months Ended	7 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Oct. 31, 2015	May 31, 2015
Energy Services
Accounts, Notes, Loans and Financing Receivable
Sale of trade receivables	$ 286.4	$ 269.0
Energy Services Funding Corporation
Accounts, Notes, Loans and Financing Receivable
Sale of undivided interests in its trade receivables to the commercial paper conduit	105.0	92.0
Outstanding balance of trade receivables	96.5	88.5
Outstanding balance of trade receivables sold	43.0	35.5
Forecast | Maximum
Accounts, Notes, Loans and Financing Receivable
Receivables facility			$ 75	$ 150