Notes Receivable (Schedule Of Current And Non-Current Notes Receivable) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	$ 119	$ 98
EnerBank notes receivable held for sale	17	41
Total notes receivable	1,077	939
EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	136	138
EnerBank notes receivable held for sale	17	41
Noncurrent notes receivable	941	800
Receivables, Excluding Held For Sale [Member] | EnerBank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable	$ 119	97
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current notes receivable		$ 1