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Related Parties (Tables) | 12 Months Ended
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Dec. 31, 2015
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
| 2015 |  | 2014 |  | 2013 |  | 2015 |  | 2014 |  | 2013
Corporate Services billings |  | $150 |  |  |  | $148 |  |  |  | $140 |  |  |  | $121 |  |  |  | $116 |  |  |  | $103 |
Sales credited | 10 |  |  | 8 |  | 7 |  | 24 |  |  | 6 |  | 12
Purchases billed | 366 |  |  | 422 |  | 365 |  | 66 |  |  | 125 |  | 68
Net Intercompany Payables | As of December 31, net intercompany payables to Corporate Services were as follows (in millions):
| 2015 |  | 2014
IPL |  | $93 |  |  |  | $84 |
WPL | 54 |  |  | 58 |
Related Amounts Billed Between Parties | The related amounts billed between the parties were as follows (in millions):
| 2015 |  | 2014 |  | 2013
ATC billings to WPL |  | $101 |  |  |  | $96 |  |  |  | $96 |
WPL billings to ATC | 13 |  |  | 9 |  |  | 12 |
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
| 2015 |  | 2014 |  | 2013 |  | 2015 |  | 2014 |  | 2013
Corporate Services billings |  | $150 |  |  |  | $148 |  |  |  | $140 |  |  |  | $121 |  |  |  | $116 |  |  |  | $103 |
Sales credited | 10 |  |  | 8 |  | 7 |  | 24 |  |  | 6 |  | 12
Purchases billed | 366 |  |  | 422 |  | 365 |  | 66 |  |  | 125 |  | 68
Net Intercompany Payables | As of December 31, net intercompany payables to Corporate Services were as follows (in millions):
| 2015 |  | 2014
IPL |  | $93 |  |  |  | $84 |
WPL | 54 |  |  | 58 |
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
| 2015 |  | 2014 |  | 2013 |  | 2015 |  | 2014 |  | 2013
Corporate Services billings |  | $150 |  |  |  | $148 |  |  |  | $140 |  |  |  | $121 |  |  |  | $116 |  |  |  | $103 |
Sales credited | 10 |  |  | 8 |  | 7 |  | 24 |  |  | 6 |  | 12
Purchases billed | 366 |  |  | 422 |  | 365 |  | 66 |  |  | 125 |  | 68
Net Intercompany Payables | As of December 31, net intercompany payables to Corporate Services were as follows (in millions):
| 2015 |  | 2014
IPL |  | $93 |  |  |  | $84 |
WPL | 54 |  |  | 58 |
Related Amounts Billed Between Parties | The related amounts billed between the parties were as follows (in millions):
| 2015 |  | 2014 |  | 2013
ATC billings to WPL |  | $101 |  |  |  | $96 |  |  |  | $96 |
WPL billings to ATC | 13 |  |  | 9 |  |  | 12 |

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