Notes Receivable (Schedule Of Allowance For Loan Losses) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 EnerBank [Member]	Dec. 31, 2013 EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses, at beginning of period	$ 5	$ 5
Charge-offs	(2)	(1)
Provision for loan losses	2	1
Allowance for loan losses, at end of period	5	5
Delinquent loans			3	4
Loans modified as troubled debt restructurings			$ 1	$ 1