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Related Parties (Tables) | 12 Months Ended
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Dec. 31, 2014
Related Party Transaction [Line Items] |
Services Provided, Sales Credited And Purchases Billed | The amounts billed for services provided, sales credited and purchases were as follows (in millions):
| IPL |  | WPL
| 2014 |  | 2013 |  | 2012 |  | 2014 |  | 2013 |  | 2012
Corporate Services billings |  | $148 |  |  |  | $140 |  |  |  | $129 |  |  |  | $116 |  |  |  | $103 |  |  |  | $102 |
Sales credited | 8 |  |  | 7 |  | 10 |  | 6 |  |  | 12 |  | 14
Purchases billed | 422 |  |  | 365 |  | 301 |  | 125 |  |  | 68 |  | 61
Net Intercompany Payables | As of December 31, net intercompany payables to Corporate Services were as follows (in millions):
| 2014 |  | 2013
IPL |  | $84 |  |  |  | $62 |
WPL | 58 |  |  | 46 |
Related Amounts Billed Between Parties | The related amounts billed between the parties were as follows (in millions):
| 2014 |  | 2013 |  | 2012
ATC billings to WPL |  | $96 |  |  |  | $96 |  |  |  | $90 |
WPL billings to ATC | 9 |  |  | 12 |  |  | 11 |
IPL [Member] |
Related Party Transaction [Line Items] |
Services Provided, Sales Credited And Purchases Billed | The amounts billed for services provided, sales credited and purchases were as follows (in millions):
| IPL |  | WPL
| 2014 |  | 2013 |  | 2012 |  | 2014 |  | 2013 |  | 2012
Corporate Services billings |  | $148 |  |  |  | $140 |  |  |  | $129 |  |  |  | $116 |  |  |  | $103 |  |  |  | $102 |
Sales credited | 8 |  |  | 7 |  | 10 |  | 6 |  |  | 12 |  | 14
Purchases billed | 422 |  |  | 365 |  | 301 |  | 125 |  |  | 68 |  | 61
Net Intercompany Payables | As of December 31, net intercompany payables to Corporate Services were as follows (in millions):
| 2014 |  | 2013
IPL |  | $84 |  |  |  | $62 |
WPL | 58 |  |  | 46 |
WPL [Member] |
Related Party Transaction [Line Items] |
Services Provided, Sales Credited And Purchases Billed | The amounts billed for services provided, sales credited and purchases were as follows (in millions):
| IPL |  | WPL
| 2014 |  | 2013 |  | 2012 |  | 2014 |  | 2013 |  | 2012
Corporate Services billings |  | $148 |  |  |  | $140 |  |  |  | $129 |  |  |  | $116 |  |  |  | $103 |  |  |  | $102 |
Sales credited | 8 |  |  | 7 |  | 10 |  | 6 |  |  | 12 |  | 14
Purchases billed | 422 |  |  | 365 |  | 301 |  | 125 |  |  | 68 |  | 61
Net Intercompany Payables | As of December 31, net intercompany payables to Corporate Services were as follows (in millions):
| 2014 |  | 2013
IPL |  | $84 |  |  |  | $62 |
WPL | 58 |  |  | 46 |
Related Amounts Billed Between Parties | The related amounts billed between the parties were as follows (in millions):
| 2014 |  | 2013 |  | 2012
ATC billings to WPL |  | $96 |  |  |  | $96 |  |  |  | $90 |
WPL billings to ATC | 9 |  |  | 12 |  |  | 11 |

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