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	6 Months Ended
	Jun. 30, 2014
Long-term Purchase Commitment [Line Items]
Minimum range of estimated future costs	$ 13
Maximum range of estimated future costs	32
Current and non-current environmental liabilities	20
IPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum range of estimated future costs	12
Maximum range of estimated future costs	30
Current and non-current environmental liabilities	18
WPL [Member]
Long-term Purchase Commitment [Line Items]
Minimum range of estimated future costs	1
Maximum range of estimated future costs	2
Current and non-current environmental liabilities	$ 2