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Related Parties (Tables) | 9 Months Ended
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Sep. 30, 2015
Related Party Transactions [Line Items] |
Services Provided, Sales Credited And Purchases | The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions):
| IPL |  | WPL
| Three Months |  | Nine Months |  | Three Months |  | Nine Months
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
Corporate Services billings |  | $38 |  |  |  | $37 |  |  |  | $114 |  |  |  | $111 |  |  |  | $30 |  |  |  | $30 |  |  |  | $90 |  |  |  | $89 |
Sales credited | 2 |  |  | 2 |  |  | 8 |  |  | 6 |  |  | 9 |  |  | 2 |  |  | 21 |  |  | 4 |
Purchases billed | 110 |  |  | 106 |  |  | 278 |  |  | 313 |  |  | 16 |  |  | 34 |  |  | 49 |  |  | 92 |
Net Intercompany Payables | Net intercompany payables to Corporate Services were as follows (in millions):
| IPL |  | WPL
| September 30, 2015 |  | December 31, 2014 |  | September 30, 2015 |  | December 31, 2014
Net payables to Corporate Services | $101 |  | $84 |  | $55 |  | $58
Related Amounts Billed Between Parties | The related amounts billed between the parties for the three and nine months ended September 30 were as follows (in millions):
| Three Months |  | Nine Months
| 2015 |  | 2014 |  | 2015 |  | 2014
ATC billings to WPL |  | $25 |  |  |  | $24 |  |  |  | $75 |  |  |  | $72 |
WPL billings to ATC | 4 |  |  | 3 |  |  | 9 |  |  | 7 |
IPL [Member] |
Related Party Transactions [Line Items] |
Services Provided, Sales Credited And Purchases | The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions):
| IPL |  | WPL
| Three Months |  | Nine Months |  | Three Months |  | Nine Months
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
Corporate Services billings |  | $38 |  |  |  | $37 |  |  |  | $114 |  |  |  | $111 |  |  |  | $30 |  |  |  | $30 |  |  |  | $90 |  |  |  | $89 |
Sales credited | 2 |  |  | 2 |  |  | 8 |  |  | 6 |  |  | 9 |  |  | 2 |  |  | 21 |  |  | 4 |
Purchases billed | 110 |  |  | 106 |  |  | 278 |  |  | 313 |  |  | 16 |  |  | 34 |  |  | 49 |  |  | 92 |
Net Intercompany Payables | Net intercompany payables to Corporate Services were as follows (in millions):
| IPL |  | WPL
| September 30, 2015 |  | December 31, 2014 |  | September 30, 2015 |  | December 31, 2014
Net payables to Corporate Services | $101 |  | $84 |  | $55 |  | $58
WPL [Member] |
Related Party Transactions [Line Items] |
Services Provided, Sales Credited And Purchases | The amounts billed for services provided, sales credited and purchases for the three and nine months ended September 30 were as follows (in millions):
| IPL |  | WPL
| Three Months |  | Nine Months |  | Three Months |  | Nine Months
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
Corporate Services billings |  | $38 |  |  |  | $37 |  |  |  | $114 |  |  |  | $111 |  |  |  | $30 |  |  |  | $30 |  |  |  | $90 |  |  |  | $89 |
Sales credited | 2 |  |  | 2 |  |  | 8 |  |  | 6 |  |  | 9 |  |  | 2 |  |  | 21 |  |  | 4 |
Purchases billed | 110 |  |  | 106 |  |  | 278 |  |  | 313 |  |  | 16 |  |  | 34 |  |  | 49 |  |  | 92 |
Net Intercompany Payables | Net intercompany payables to Corporate Services were as follows (in millions):
| IPL |  | WPL
| September 30, 2015 |  | December 31, 2014 |  | September 30, 2015 |  | December 31, 2014
Net payables to Corporate Services | $101 |  | $84 |  | $55 |  | $58
Related Amounts Billed Between Parties | The related amounts billed between the parties for the three and nine months ended September 30 were as follows (in millions):
| Three Months |  | Nine Months
| 2015 |  | 2014 |  | 2015 |  | 2014
ATC billings to WPL |  | $25 |  |  |  | $24 |  |  |  | $75 |  |  |  | $72 |
WPL billings to ATC | 4 |  |  | 3 |  |  | 9 |  |  | 7 |

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