Receivables (Maximum And Average Outstanding Cash Proceeds) (Details) - IPL [Member] - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding aggregate cash proceeds (based on daily outstanding balances)	$ 112.0	$ 172.0	$ 137.0
Average [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding aggregate cash proceeds (based on daily outstanding balances)	$ 62.2	$ 73.2	$ 46.7

The cash inflow associated with the proceeds from sale and collection of receivables during the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3179-108585

Name:	us-gaap_ProceedsFromSaleAndCollectionOfReceivables
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration