Commitments And Contingencies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 2,438
Performance guarantees outstanding	313
Present value abandonment obligation	31
IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	1,922
Number of sites monitoring and remediating (in sites)	26
WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	514
Number of sites monitoring and remediating (in sites)	5
Capital Purchase Obligation [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	45
Capital Purchase Obligation [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	26
Capital Purchase Obligation [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	19
Performance guarantees outstanding, 2014 [Member]
Commitments and Contingencies [Line Items]
Performance guarantees outstanding	137
Performance guarantees outstanding, 2015 [Member]
Commitments and Contingencies [Line Items]
Performance guarantees outstanding	53
Performance guarantees outstanding, 2016 [Member]
Commitments and Contingencies [Line Items]
Performance guarantees outstanding	123
Environmental Issue [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Environmental mitigation projects to be completed, value	$ 7
Minimum [Member]
Commitments and Contingencies [Line Items]
Warranty period	12 months
Maximum [Member]
Commitments and Contingencies [Line Items]
Warranty period	60 months