v2.4.0.6

Related Parties (Tables) | 12 Months Ended
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Dec. 31, 2012
Related Party Transaction [Line Items] |
Sales Credited and Purchases Billed | The sales credited to and purchases billed to IPL and WPL were as follows (in millions):
| IPL |  | WPL
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Sales credited |  | $10 |  |  |  | $31 |  |  |  | $28 |  |  |  | $14 |  |  |  | $28 |  |  |  | $24 |
Purchases billed | 301 |  |  | 307 |  |  | 341 |  |  | 61 |  |  | 77 |  |  | 73 |
Corporate Services Billings | The amounts billed to IPL and WPL were as follows (in millions):
| IPL |  | WPL
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Corporate Services billings |  | $129 |  |  |  | $153 |  |  |  | $170 |  |  |  | $102 |  |  |  | $119 |  |  |  | $127 |
Net Intercompany Payables | As of December 31, net intercompany payables to Corporate Services were as follows (in millions):
| 2012 |  | 2011
IPL |  | $72 |  |  |  | $82 |
WPL | 40 |  |  | 48 |
Related Amounts Billed Between Parties | The related amounts billed between the parties were as follows (in millions):
| 2012 |  | 2011 |  | 2010
ATC billings to WPL |  | $90 |  |  |  | $90 |  |  |  | $92 |
WPL billings to ATC | 11 |  |  | 12 |  |  | 11 |
IPL [Member] |
Related Party Transaction [Line Items] |
Sales Credited and Purchases Billed | The sales credited to and purchases billed to IPL and WPL were as follows (in millions):
| IPL |  | WPL
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Sales credited |  | $10 |  |  |  | $31 |  |  |  | $28 |  |  |  | $14 |  |  |  | $28 |  |  |  | $24 |
Purchases billed | 301 |  |  | 307 |  |  | 341 |  |  | 61 |  |  | 77 |  |  | 73 |
Corporate Services Billings | The amounts billed to IPL and WPL were as follows (in millions):
| IPL |  | WPL
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Corporate Services billings |  | $129 |  |  |  | $153 |  |  |  | $170 |  |  |  | $102 |  |  |  | $119 |  |  |  | $127 |
Net Intercompany Payables | As of December 31, net intercompany payables to Corporate Services were as follows (in millions):
| 2012 |  | 2011
IPL |  | $72 |  |  |  | $82 |
WPL | 40 |  |  | 48 |
WPL [Member] |
Related Party Transaction [Line Items] |
Sales Credited and Purchases Billed | The sales credited to and purchases billed to IPL and WPL were as follows (in millions):
| IPL |  | WPL
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Sales credited |  | $10 |  |  |  | $31 |  |  |  | $28 |  |  |  | $14 |  |  |  | $28 |  |  |  | $24 |
Purchases billed | 301 |  |  | 307 |  |  | 341 |  |  | 61 |  |  | 77 |  |  | 73 |
Corporate Services Billings | The amounts billed to IPL and WPL were as follows (in millions):
| IPL |  | WPL
| 2012 |  | 2011 |  | 2010 |  | 2012 |  | 2011 |  | 2010
Corporate Services billings |  | $129 |  |  |  | $153 |  |  |  | $170 |  |  |  | $102 |  |  |  | $119 |  |  |  | $127 |
Net Intercompany Payables | As of December 31, net intercompany payables to Corporate Services were as follows (in millions):
| 2012 |  | 2011
IPL |  | $72 |  |  |  | $82 |
WPL | 40 |  |  | 48 |
Related Amounts Billed Between Parties | The related amounts billed between the parties were as follows (in millions):
| 2012 |  | 2011 |  | 2010
ATC billings to WPL |  | $90 |  |  |  | $90 |  |  |  | $92 |
WPL billings to ATC | 11 |  |  | 12 |  |  | 11 |

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