Receivables (Maximum And Average Outstanding Cash Proceeds) (Details) - IPL [Member] - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Receivables [Line Items]
Outstanding aggregate cash proceeds (based on daily outstanding balances)	$ 52.3	$ 71.1	$ 56.7	$ 54.8
Maximum [Member]
Receivables [Line Items]
Outstanding aggregate cash proceeds (based on daily outstanding balances)	$ 116.0	$ 97.0	$ 116.0	$ 97.0

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
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585

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