Commitments And Contingencies Commitments And Contingencies (MPG Site Estimated Future Costs And Recorded Liabilities) (Details) (Manufactured Gas Plant Sites [Member], USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies [Line Items]
Minimum range of estimated future costs	$ 13
Maximum range of estimated future costs	32
Current and non-current environmental liabilities	19
IPL [Member]
Commitments and Contingencies [Line Items]
Minimum range of estimated future costs	12
Maximum range of estimated future costs	30
Current and non-current environmental liabilities	17
WPL [Member]
Commitments and Contingencies [Line Items]
Minimum range of estimated future costs	1
Maximum range of estimated future costs	2
Current and non-current environmental liabilities	$ 2