Commitments And Contingencies (Schedule Of Environmental Liabilities) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Minimum range of estimated future cost incurred for investigation, remediation and monitoring	$ 14
Maximum remaining estimated cost incurred for investigation, remediation and monitoring	27
IPL [Member]
Minimum range of estimated future cost incurred for investigation, remediation and monitoring	12
Maximum remaining estimated cost incurred for investigation, remediation and monitoring	24
Manufactured Gas Plant [Member]
Total environmental liabilities	16
Manufactured Gas Plant [Member] | IPL [Member]
Total environmental liabilities	$ 13