XML 80 R91.htm IDEA: XBRL DOCUMENT v2.4.0.6
Related Parties (Net Intercompany Payables) (Details) (USD $)
In Millions, unless otherwise specified
Sep. 30, 2012
Dec. 31, 2011
IPL [Member]
   
Related Party Transaction [Line Items]    
Net payables to Corporate Services $ 80 $ 82
WPL [Member]
   
Related Party Transaction [Line Items]    
Net payables to Corporate Services $ 49 $ 48