Receivables (Additional Attributes Of Receivables Sold Under The Agreement) (Details) - IPL [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collections reinvested in receivables	$ 1,647.1	$ 1,818.1	$ 1,812.9
Write-offs, net of recoveries	$ 17.7	$ 4.8	$ 8.8