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Commitments And Contingencies (Operating Expense Purchase Obligations) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2014
Long-term Purchase Commitment [Line Items]  
Individual commitments incurred $ 1
Scenario, Forecast [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 2,518
Scenario, Forecast [Member] | IPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 1,955
Scenario, Forecast [Member] | WPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 560
Scenario, Forecast [Member] | Other [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 33 [1]
Scenario, Forecast [Member] | Other [Member] | IPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 21 [1]
Scenario, Forecast [Member] | Other [Member] | WPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 9 [1]
Scenario, Forecast [Member] | Natural Gas [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 276
Scenario, Forecast [Member] | Natural Gas [Member] | IPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 146
Scenario, Forecast [Member] | Natural Gas [Member] | WPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 130
Scenario, Forecast [Member] | Coal [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 309 [2]
Scenario, Forecast [Member] | Coal [Member] | IPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 134 [2]
Scenario, Forecast [Member] | Coal [Member] | WPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 175 [2]
Scenario, Forecast [Member] | SO2 emission allowances [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 34
Scenario, Forecast [Member] | SO2 emission allowances [Member] | IPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 34
Scenario, Forecast [Member] | SO2 emission allowances [Member] | WPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 0
Scenario, Forecast [Member] | Purchased Power [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 1,866 [3]
Scenario, Forecast [Member] | Purchased Power [Member] | IPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 1,620 [3]
Scenario, Forecast [Member] | Purchased Power [Member] | WPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 246 [3]
Scenario, Forecast [Member] | Purchased Power [Member] | DAEC (IPL) [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 1,619 [3]
Scenario, Forecast [Member] | Purchased Power [Member] | DAEC (IPL) [Member] | IPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 1,619 [3]
Scenario, Forecast [Member] | Purchased Power [Member] | DAEC (IPL) [Member] | WPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 0 [3]
Scenario, Forecast [Member] | Purchased Power [Member] | Other [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 247 [3]
Scenario, Forecast [Member] | Purchased Power [Member] | Other [Member] | IPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments 1 [3]
Scenario, Forecast [Member] | Purchased Power [Member] | Other [Member] | WPL [Member]
  
Long-term Purchase Commitment [Line Items]  
Minimum future commitments $ 246 [3]
[1] Includes individual commitments incurred during the normal course of business that exceeded $1 million at March 31, 2014.
[2] Corporate Services entered into system-wide coal contracts on behalf of IPL and WPL that include minimum future commitments. These commitments were assigned to IPL and WPL based on information available as of March 31, 2014 regarding expected future usage, which is subject to change.
[3] Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased.