Notes Receivable (Schedule Of Current And Non-Current Notes Receivable) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	$ 114	$ 98
Total notes receivable	991	939
EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	113	138
Noncurrent notes receivable	877	800
Receivables, Excluding Held For Sale [Member] | EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	113	97
Receivables Held For Sale [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable		41
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	$ 1	$ 1