Commitments And Contingencies (MPG Site Estimated Future Costs And Recorded Liabilities) (Details) - Jun. 30, 2015 - Manufactured Gas Plant Sites [Member] - USD ($) $ in Millions	Total
Commitments and Contingencies [Line Items]
Minimum range of estimated future costs	$ 12
Maximum range of estimated future costs	29
Current and non-current environmental liabilities	16
IPL [Member]
Commitments and Contingencies [Line Items]
Minimum range of estimated future costs	10
Maximum range of estimated future costs	26
Current and non-current environmental liabilities	14
WPL [Member]
Commitments and Contingencies [Line Items]
Minimum range of estimated future costs	2
Maximum range of estimated future costs	3
Current and non-current environmental liabilities	$ 2