Receivables (Maximum And Average Outstanding Cash Proceeds) (Details) - IPL [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding aggregate cash proceeds (based on daily outstanding balances)	$ 180.0	$ 180.0	$ 180.0
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding aggregate cash proceeds (based on daily outstanding balances)	172.0	137.0	150.0
Average [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding aggregate cash proceeds (based on daily outstanding balances)	$ 73.2	$ 46.7	$ 46.4