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Investments (Tables) | 12 Months Ended
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Dec. 31, 2024
Schedule of Equity Method Investments [Line Items] |
Unconsolidated Equity Investments | Alliant Energy’s unconsolidated investments accounted for under the equity method of accounting are as follows (in millions):
| Ownership Interest at |  | Carrying Value at December 31, |  | Equity (Income) / Loss
| December 31, 2024 |  | 2024 |  | 2023 |  | 2024 |  | 2023 |  | 2022
ATC Holdings | 16%, 20% |  | $415 |  | $386 |  | ($57) |  | ($49) |  | ($41)
Non-utility wind farm in Oklahoma | 50% |  | 107 |  | 104 |  | (6) |  | (7) |  | (5)
Corporate venture investments | Various |  | 78 |  | 74 |  | 3 |  | (2) |  | (3)
Other | Various |  | 23 |  | 21 |  | (1) |  | (3) |  | (2)
|  |  | $623 |  | $585 |  | ($61) |  | ($61) |  | ($51)
Summary Financial Information | Summary aggregate financial information from the financial statements of these holdings is as follows (in millions):
| Alliant Energy |  |
| 2024 |  | 2023 |  | 2022 |  |  |  |  |  |
Revenues | $1,005 |  | $898 |  | $813 |  |  |  |  |  |
Operating income | 433 |  | 384 |  | 350 |  |  |  |  |  |
Net income | 434 |  | 370 |  | 675 |  |  |  |  |  |
As of December 31: |  |  |  |  |  |  |  |  |  |  |
Current assets | 223 |  | 221 |  |  |  |  |  |  |  |
Non-current assets | 9,930 |  | 9,032 |  |  |  |  |  |  |  |
Current liabilities | 524 |  | 528 |  |  |  |  |  |  |  |
Non-current liabilities | 3,933 |  | 3,584 |  |  |  |  |  |  |  |
Noncontrolling interest | 221 |  | 259 |  |  |  |  |  |  |  |

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