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Investments | 9 Months Ended
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Sep. 30, 2013
Schedule of Equity Method Investments [Line Items] |
Investments | INVESTMENTS Unconsolidated Equity Investments - Equity (income) loss from Alliant Energy’s and WPL’s unconsolidated investments accounted for under the equity method of accounting for the three and nine months ended September 30 was as follows (in millions):
| Alliant Energy |  | WPL
| Three Months |  | Nine Months |  | Three Months |  | Nine Months
| 2013 |  | 2012 |  | 2013 |  | 2012 |  | 2013 |  | 2012 |  | 2013 |  | 2012
ATC |  | ($10.8 | ) |  |  | ($10.4 | ) |  |  | ($31.7 | ) |  |  | ($30.6 | ) |  |  | ($10.8 | ) |  |  | ($10.4 | ) |  |  | ($31.7 | ) |  |  | ($30.6 | )
Other | (0.3 | ) |  | — |  |  | (1.0 | ) |  | 0.2 |  |  | (0.3 | ) |  | (0.1 | ) |  | (1.0 | ) |  | (0.6 | )
|  | ($11.1 | ) |  |  | ($10.4 | ) |  |  | ($32.7 | ) |  |  | ($30.4 | ) |  |  | ($11.1 | ) |  |  | ($10.5 | ) |  |  | ($32.7 | ) |  |  | ($31.2 | )
Summary financial information from the unaudited financial statements of ATC for the three and nine months ended September 30 was as follows (in millions):
| Three Months |  | Nine Months
| 2013 |  | 2012 |  | 2013 |  | 2012
Operating revenues |  | $160.4 |  |  |  | $150.3 |  |  |  | $464.3 |  |  |  | $450.1 |
Operating income | 82.9 |  |  | 81.5 |  |  | 247.1 |  |  | 240.0 |
Net income | 62.7 |  |  | 60.5 |  |  | 184.5 |  |  | 177.9 |
WPL [Member] |
Schedule of Equity Method Investments [Line Items] |
Investments | INVESTMENTS Unconsolidated Equity Investments - Equity (income) loss from Alliant Energy’s and WPL’s unconsolidated investments accounted for under the equity method of accounting for the three and nine months ended September 30 was as follows (in millions):
| Alliant Energy |  | WPL
| Three Months |  | Nine Months |  | Three Months |  | Nine Months
| 2013 |  | 2012 |  | 2013 |  | 2012 |  | 2013 |  | 2012 |  | 2013 |  | 2012
ATC |  | ($10.8 | ) |  |  | ($10.4 | ) |  |  | ($31.7 | ) |  |  | ($30.6 | ) |  |  | ($10.8 | ) |  |  | ($10.4 | ) |  |  | ($31.7 | ) |  |  | ($30.6 | )
Other | (0.3 | ) |  | — |  |  | (1.0 | ) |  | 0.2 |  |  | (0.3 | ) |  | (0.1 | ) |  | (1.0 | ) |  | (0.6 | )
|  | ($11.1 | ) |  |  | ($10.4 | ) |  |  | ($32.7 | ) |  |  | ($30.4 | ) |  |  | ($11.1 | ) |  |  | ($10.5 | ) |  |  | ($32.7 | ) |  |  | ($31.2 | )
Summary financial information from the unaudited financial statements of ATC for the three and nine months ended September 30 was as follows (in millions):
| Three Months |  | Nine Months
| 2013 |  | 2012 |  | 2013 |  | 2012
Operating revenues |  | $160.4 |  |  |  | $150.3 |  |  |  | $464.3 |  |  |  | $450.1 |
Operating income | 82.9 |  |  | 81.5 |  |  | 247.1 |  |  | 240.0 |
Net income | 62.7 |  |  | 60.5 |  |  | 184.5 |  |  | 177.9 |

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