XML 181 R81.htm IDEA: XBRL DOCUMENT v2.4.0.8
Commitments And Contingencies (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
 1 Months Ended 6 Months Ended 1 Months Ended 6 Months Ended 12 Months Ended 1 Months Ended 6 Months Ended
Jul. 31, 2012
subclass
Dec. 31, 2010
Jun. 30, 2013
Jun. 30, 2013
IPL [Member]
site
Jun. 30, 2013
WPL [Member]
site
Jun. 30, 2013
Manufactured Gas Plant Sites [Member]
Jun. 30, 2013
Manufactured Gas Plant Sites [Member]
IPL [Member]
Jun. 30, 2013
Manufactured Gas Plant Sites [Member]
WPL [Member]
Jun. 30, 2013
Indemnifications [Member]
RMT [Member]
Sep. 30, 2012
Defined benefit pension plans [Member]
Jun. 30, 2013
Defined benefit pension plans [Member]
Dec. 31, 2011
Defined benefit pension plans [Member]
Feb. 28, 2013
Defined benefit pension plans [Member]
Cash Balance Plan [Member]
Sep. 30, 2012
Defined benefit pension plans [Member]
Cash Balance Plan [Member]
Jun. 30, 2013
Performance guarantees outstanding, 2013 [Member]
Jun. 30, 2013
Performance guarantees outstanding, 2014 [Member]
Jun. 30, 2013
Performance guarantees outstanding, 2015 [Member]
Jun. 30, 2013
Scenario, Forecast [Member]
Jun. 30, 2013
Scenario, Forecast [Member]
IPL [Member]
Jun. 30, 2013
Scenario, Forecast [Member]
WPL [Member]
Jun. 30, 2013
Scenario, Forecast [Member]
Capital Purchase Obligation [Member]
Jun. 30, 2013
Scenario, Forecast [Member]
Capital Purchase Obligation [Member]
IPL [Member]
Jun. 30, 2013
Scenario, Forecast [Member]
Capital Purchase Obligation [Member]
WPL [Member]
Jun. 30, 2013
Civil Penalty [Member]
WPL [Member]
Jun. 30, 2013
Environmental Issue [Member]
WPL [Member]
Jun. 30, 2013
Minimum [Member]
Jun. 30, 2013
Maximum [Member]
Long-term Purchase Commitment [Line Items]                                                      
Minimum future commitments                                   $ 2,728 $ 2,164 $ 559 $ 65 $ 21 $ 44        
Loss contingency, damages awarded, value                         6.4                     2.0 7.0    
Interest crediting rate   8.20%                                                  
Aggregate additional payments to certain plan participants                       10                              
Number of new subclasses certified as a result of court opinion and order 2                                                    
Loss contingency, damages sought, value                           9.6                          
Damages to be paid out of common fund                   4.3                                  
Estimated damages from court opinion and order                     18.7                                
Loss contingency, estimate of possible loss                 3                                    
Warranty period                                                   12 months 60 months
Performance guarantees outstanding     546                       199 294 53                    
Present value abandonment obligation     31                                                
Number of sites monitoring and remediating (in sites)       27 5                                            
Minimum remaining estimated cost incurred for investigation, remediation and monitoring                                   16 14 2              
Maximum remaining estimated cost incurred for investigation, remediation and monitoring                                   30 26 4              
Current and non-current environmental liabilities           $ 26 $ 23 $ 3