Commitments And Contingencies (Schedule Of Environmental Liabilities) (Details) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($)
Minimum range of estimated future cost incurred for investigation, remediation and monitoring	$ 11
Maximum remaining estimated cost incurred for investigation, remediation and monitoring	30
IPL [Member]
Minimum range of estimated future cost incurred for investigation, remediation and monitoring	9
Maximum remaining estimated cost incurred for investigation, remediation and monitoring	27
Manufactured Gas Plant [Member]
Total environmental liabilities	15
Manufactured Gas Plant [Member] \| IPL [Member]
Total environmental liabilities	$ 13

Total costs accrued as of the balance sheet date for environmental loss contingencies.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346

Name:	us-gaap_AccrualForEnvironmentalLossContingencies
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant