Receivables (Maximum And Average Outstanding Cash Proceeds) (Details) - IPL [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Receivables [Line Items]
Outstanding aggregate cash proceeds (based on daily outstanding balances)	$ 36.4	$ 66.2	$ 49.8	$ 58.7
Maximum [Member]
Receivables [Line Items]
Outstanding aggregate cash proceeds (based on daily outstanding balances)	$ 110.0	$ 112.0	$ 116.0	$ 112.0