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Revenues (Tables) | 12 Months Ended
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Dec. 31, 2024
Disaggregation of Revenue [Line Items] |
Disaggregation of Revenues | Disaggregation of revenues from contracts with customers is provided for each reportable segment (IPL and WPL), as well as by customer class within electric and gas sales, as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2024 |  | 2023 |  | 2022 |  | 2024 |  | 2023 |  | 2022 |  | 2024 |  | 2023 |  | 2022
Electric Utility: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retail - residential | $1,236 |  |  | $1,220 |  |  | $1,233 |  |  | $640 |  |  | $641 |  |  | $673 |  |  | $596 |  |  | $579 |  |  | $560 |
Retail - commercial | 821 |  |  | 820 |  |  | 821 |  |  | 525 |  |  | 519 |  |  | 536 |  |  | 296 |  |  | 301 |  |  | 285 |
Retail - industrial | 952 |  |  | 968 |  |  | 965 |  |  | 497 |  |  | 501 |  |  | 538 |  |  | 455 |  |  | 467 |  |  | 427 |
Wholesale | 200 |  |  | 213 |  |  | 233 |  |  | 61 |  |  | 62 |  |  | 64 |  |  | 139 |  |  | 151 |  |  | 169 |
Bulk power and other | 163 |  |  | 124 |  |  | 169 |  |  | 24 |  |  | 38 |  |  | 48 |  |  | 139 |  |  | 86 |  |  | 121 |
Total Electric Utility | 3,372 |  |  | 3,345 |  |  | 3,421 |  |  | 1,747 |  |  | 1,761 |  |  | 1,859 |  |  | 1,625 |  |  | 1,584 |  |  | 1,562 |
Gas Utility: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retail - residential | 275 |  |  | 316 |  |  | 371 |  |  | 148 |  |  | 176 |  |  | 202 |  |  | 127 |  |  | 140 |  |  | 169 |
Retail - commercial | 133 |  |  | 163 |  |  | 197 |  |  | 68 |  |  | 86 |  |  | 101 |  |  | 65 |  |  | 77 |  |  | 96 |
Retail - industrial | 11 |  |  | 16 |  |  | 20 |  |  | 7 |  |  | 11 |  |  | 14 |  |  | 4 |  |  | 5 |  |  | 6 |
Transportation/other | 46 |  |  | 45 |  |  | 54 |  |  | 27 |  |  | 27 |  |  | 34 |  |  | 19 |  |  | 18 |  |  | 20 |
Total Gas Utility | 465 |  |  | 540 |  |  | 642 |  |  | 250 |  |  | 300 |  |  | 351 |  |  | 215 |  |  | 240 |  |  | 291 |
Other Utility: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Steam | 40 |  |  | 45 |  |  | 39 |  |  | 40 |  |  | 45 |  |  | 39 |  |  | — |  |  | — |  |  | — |
Other utility | 14 |  |  | 7 |  |  | 10 |  |  | 9 |  |  | 4 |  |  | 7 |  |  | 5 |  |  | 3 |  |  | 3 |
Total Other Utility | 54 |  |  | 52 |  |  | 49 |  |  | 49 |  |  | 49 |  |  | 46 |  |  | 5 |  |  | 3 |  |  | 3 |
Non-Utility and Other: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Travero and other | 90 |  |  | 90 |  |  | 93 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Total Non-Utility and Other | 90 |  |  | 90 |  |  | 93 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Total revenues | $3,981 |  |  | $4,027 |  |  | $4,205 |  |  | $2,046 |  |  | $2,110 |  |  | $2,256 |  |  | $1,845 |  |  | $1,827 |  |  | $1,856 |
IPL [Member] |
Disaggregation of Revenue [Line Items] |
Disaggregation of Revenues | Disaggregation of revenues from contracts with customers is provided for each reportable segment (IPL and WPL), as well as by customer class within electric and gas sales, as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2024 |  | 2023 |  | 2022 |  | 2024 |  | 2023 |  | 2022 |  | 2024 |  | 2023 |  | 2022
Electric Utility: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retail - residential | $1,236 |  |  | $1,220 |  |  | $1,233 |  |  | $640 |  |  | $641 |  |  | $673 |  |  | $596 |  |  | $579 |  |  | $560 |
Retail - commercial | 821 |  |  | 820 |  |  | 821 |  |  | 525 |  |  | 519 |  |  | 536 |  |  | 296 |  |  | 301 |  |  | 285 |
Retail - industrial | 952 |  |  | 968 |  |  | 965 |  |  | 497 |  |  | 501 |  |  | 538 |  |  | 455 |  |  | 467 |  |  | 427 |
Wholesale | 200 |  |  | 213 |  |  | 233 |  |  | 61 |  |  | 62 |  |  | 64 |  |  | 139 |  |  | 151 |  |  | 169 |
Bulk power and other | 163 |  |  | 124 |  |  | 169 |  |  | 24 |  |  | 38 |  |  | 48 |  |  | 139 |  |  | 86 |  |  | 121 |
Total Electric Utility | 3,372 |  |  | 3,345 |  |  | 3,421 |  |  | 1,747 |  |  | 1,761 |  |  | 1,859 |  |  | 1,625 |  |  | 1,584 |  |  | 1,562 |
Gas Utility: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retail - residential | 275 |  |  | 316 |  |  | 371 |  |  | 148 |  |  | 176 |  |  | 202 |  |  | 127 |  |  | 140 |  |  | 169 |
Retail - commercial | 133 |  |  | 163 |  |  | 197 |  |  | 68 |  |  | 86 |  |  | 101 |  |  | 65 |  |  | 77 |  |  | 96 |
Retail - industrial | 11 |  |  | 16 |  |  | 20 |  |  | 7 |  |  | 11 |  |  | 14 |  |  | 4 |  |  | 5 |  |  | 6 |
Transportation/other | 46 |  |  | 45 |  |  | 54 |  |  | 27 |  |  | 27 |  |  | 34 |  |  | 19 |  |  | 18 |  |  | 20 |
Total Gas Utility | 465 |  |  | 540 |  |  | 642 |  |  | 250 |  |  | 300 |  |  | 351 |  |  | 215 |  |  | 240 |  |  | 291 |
Other Utility: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Steam | 40 |  |  | 45 |  |  | 39 |  |  | 40 |  |  | 45 |  |  | 39 |  |  | — |  |  | — |  |  | — |
Other utility | 14 |  |  | 7 |  |  | 10 |  |  | 9 |  |  | 4 |  |  | 7 |  |  | 5 |  |  | 3 |  |  | 3 |
Total Other Utility | 54 |  |  | 52 |  |  | 49 |  |  | 49 |  |  | 49 |  |  | 46 |  |  | 5 |  |  | 3 |  |  | 3 |
Non-Utility and Other: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Travero and other | 90 |  |  | 90 |  |  | 93 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Total Non-Utility and Other | 90 |  |  | 90 |  |  | 93 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Total revenues | $3,981 |  |  | $4,027 |  |  | $4,205 |  |  | $2,046 |  |  | $2,110 |  |  | $2,256 |  |  | $1,845 |  |  | $1,827 |  |  | $1,856 |
WPL [Member] |
Disaggregation of Revenue [Line Items] |
Disaggregation of Revenues | Disaggregation of revenues from contracts with customers is provided for each reportable segment (IPL and WPL), as well as by customer class within electric and gas sales, as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2024 |  | 2023 |  | 2022 |  | 2024 |  | 2023 |  | 2022 |  | 2024 |  | 2023 |  | 2022
Electric Utility: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retail - residential | $1,236 |  |  | $1,220 |  |  | $1,233 |  |  | $640 |  |  | $641 |  |  | $673 |  |  | $596 |  |  | $579 |  |  | $560 |
Retail - commercial | 821 |  |  | 820 |  |  | 821 |  |  | 525 |  |  | 519 |  |  | 536 |  |  | 296 |  |  | 301 |  |  | 285 |
Retail - industrial | 952 |  |  | 968 |  |  | 965 |  |  | 497 |  |  | 501 |  |  | 538 |  |  | 455 |  |  | 467 |  |  | 427 |
Wholesale | 200 |  |  | 213 |  |  | 233 |  |  | 61 |  |  | 62 |  |  | 64 |  |  | 139 |  |  | 151 |  |  | 169 |
Bulk power and other | 163 |  |  | 124 |  |  | 169 |  |  | 24 |  |  | 38 |  |  | 48 |  |  | 139 |  |  | 86 |  |  | 121 |
Total Electric Utility | 3,372 |  |  | 3,345 |  |  | 3,421 |  |  | 1,747 |  |  | 1,761 |  |  | 1,859 |  |  | 1,625 |  |  | 1,584 |  |  | 1,562 |
Gas Utility: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Retail - residential | 275 |  |  | 316 |  |  | 371 |  |  | 148 |  |  | 176 |  |  | 202 |  |  | 127 |  |  | 140 |  |  | 169 |
Retail - commercial | 133 |  |  | 163 |  |  | 197 |  |  | 68 |  |  | 86 |  |  | 101 |  |  | 65 |  |  | 77 |  |  | 96 |
Retail - industrial | 11 |  |  | 16 |  |  | 20 |  |  | 7 |  |  | 11 |  |  | 14 |  |  | 4 |  |  | 5 |  |  | 6 |
Transportation/other | 46 |  |  | 45 |  |  | 54 |  |  | 27 |  |  | 27 |  |  | 34 |  |  | 19 |  |  | 18 |  |  | 20 |
Total Gas Utility | 465 |  |  | 540 |  |  | 642 |  |  | 250 |  |  | 300 |  |  | 351 |  |  | 215 |  |  | 240 |  |  | 291 |
Other Utility: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Steam | 40 |  |  | 45 |  |  | 39 |  |  | 40 |  |  | 45 |  |  | 39 |  |  | — |  |  | — |  |  | — |
Other utility | 14 |  |  | 7 |  |  | 10 |  |  | 9 |  |  | 4 |  |  | 7 |  |  | 5 |  |  | 3 |  |  | 3 |
Total Other Utility | 54 |  |  | 52 |  |  | 49 |  |  | 49 |  |  | 49 |  |  | 46 |  |  | 5 |  |  | 3 |  |  | 3 |
Non-Utility and Other: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Travero and other | 90 |  |  | 90 |  |  | 93 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Total Non-Utility and Other | 90 |  |  | 90 |  |  | 93 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Total revenues | $3,981 |  |  | $4,027 |  |  | $4,205 |  |  | $2,046 |  |  | $2,110 |  |  | $2,256 |  |  | $1,845 |  |  | $1,827 |  |  | $1,856 |

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