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Regulatory Matters (Tables) | 12 Months Ended
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Dec. 31, 2022
Regulatory Assets [Line Items] |
Schedule of Regulatory Assets | At December 31, regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Tax-related | $929 |  |  | $934 |  |  | $848 |  |  | $884 |  |  | $81 |  |  | $50 |
Pension and OPEB costs | 392 |  |  | 462 |  |  | 197 |  |  | 228 |  |  | 195 |  |  | 234 |
Commodity cost recovery | 160 |  |  | 42 |  |  | 1 |  |  | 2 |  |  | 159 |  |  | 40 |
AROs | 151 |  |  | 128 |  |  | 110 |  |  | 89 |  |  | 41 |  |  | 39 |
Derivatives | 84 |  |  | 8 |  |  | 48 |  |  | 4 |  |  | 36 |  |  | 4 |
Assets retired early | 70 |  |  | 92 |  |  | 53 |  |  | 66 |  |  | 17 |  |  | 26 |
IPL’s DAEC PPA amendment | 66 |  |  | 90 |  |  | 66 |  |  | 90 |  |  | — |  |  | — |
WPL’s Western Wisconsin gas distribution expansion investments | 48 |  |  | 52 |  |  | — |  |  | — |  |  | 48 |  |  | 52 |
Other | 146 |  |  | 132 |  |  | 63 |  |  | 80 |  |  | 83 |  |  | 52 |
| $2,046 |  |  | $1,940 |  |  | $1,386 |  |  | $1,443 |  |  | $660 |  |  | $497 |
Assets Retired Early | Details regarding the recovery of the remaining net book value of these assets from IPL’s and WPL’s customers are as follows (dollars in millions):
Entity |  | Asset |  | Retirement Date |  | Regulatory Asset Balance as of Dec. 31, 2022 |  | Recovery |  | Regulatory Approval
IPL |  | Sutherland Units 1 and 3 |  | 2017 |  | $16 |  | Return of and return on remaining net book value through 2027 |  | IUB and FERC
IPL |  | M.L. Kapp Unit 2 |  | 2018 |  | 13 |  | Return of and return on remaining net book value through 2029 |  | IUB and FERC
IPL |  | Analog electric meters |  | 2019 |  | 24 |  | Return of remaining net book value through 2028 |  | IUB and FERC
WPL |  | Edgewater Unit 4 |  | 2018 |  | 17 |  | Return of and return on remaining net book value through 2028 |  | PSCW and FERC
Schedule of Regulatory Liabilities | At December 31, regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Tax-related | $579 |  | $585 |  | $303 |  | $312 |  | $276 |  | $273
Cost of removal obligations | 398 |  | 384 |  | 259 |  | 252 |  | 139 |  | 132
Derivatives | 210 |  | 166 |  | 115 |  | 77 |  | 95 |  | 89
Commodity cost recovery | 40 |  | 17 |  | 38 |  | 15 |  | 2 |  | 2
WPL’s West Riverside liquidated damages | 32 |  | 36 |  | — |  | — |  | 32 |  | 36
Electric transmission cost recovery | 20 |  | 51 |  | 10 |  | 27 |  | 10 |  | 24
Other | 45 |  | 32 |  | 29 |  | 8 |  | 16 |  | 24
| $1,324 |  | $1,271 |  | $754 |  | $691 |  | $570 |  | $580
IPL [Member] |
Regulatory Assets [Line Items] |
Schedule of Regulatory Assets | At December 31, regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Tax-related | $929 |  |  | $934 |  |  | $848 |  |  | $884 |  |  | $81 |  |  | $50 |
Pension and OPEB costs | 392 |  |  | 462 |  |  | 197 |  |  | 228 |  |  | 195 |  |  | 234 |
Commodity cost recovery | 160 |  |  | 42 |  |  | 1 |  |  | 2 |  |  | 159 |  |  | 40 |
AROs | 151 |  |  | 128 |  |  | 110 |  |  | 89 |  |  | 41 |  |  | 39 |
Derivatives | 84 |  |  | 8 |  |  | 48 |  |  | 4 |  |  | 36 |  |  | 4 |
Assets retired early | 70 |  |  | 92 |  |  | 53 |  |  | 66 |  |  | 17 |  |  | 26 |
IPL’s DAEC PPA amendment | 66 |  |  | 90 |  |  | 66 |  |  | 90 |  |  | — |  |  | — |
WPL’s Western Wisconsin gas distribution expansion investments | 48 |  |  | 52 |  |  | — |  |  | — |  |  | 48 |  |  | 52 |
Other | 146 |  |  | 132 |  |  | 63 |  |  | 80 |  |  | 83 |  |  | 52 |
| $2,046 |  |  | $1,940 |  |  | $1,386 |  |  | $1,443 |  |  | $660 |  |  | $497 |
Assets Retired Early | Details regarding the recovery of the remaining net book value of these assets from IPL’s and WPL’s customers are as follows (dollars in millions):
Entity |  | Asset |  | Retirement Date |  | Regulatory Asset Balance as of Dec. 31, 2022 |  | Recovery |  | Regulatory Approval
IPL |  | Sutherland Units 1 and 3 |  | 2017 |  | $16 |  | Return of and return on remaining net book value through 2027 |  | IUB and FERC
IPL |  | M.L. Kapp Unit 2 |  | 2018 |  | 13 |  | Return of and return on remaining net book value through 2029 |  | IUB and FERC
IPL |  | Analog electric meters |  | 2019 |  | 24 |  | Return of remaining net book value through 2028 |  | IUB and FERC
WPL |  | Edgewater Unit 4 |  | 2018 |  | 17 |  | Return of and return on remaining net book value through 2028 |  | PSCW and FERC
Schedule of Regulatory Liabilities | At December 31, regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Tax-related | $579 |  | $585 |  | $303 |  | $312 |  | $276 |  | $273
Cost of removal obligations | 398 |  | 384 |  | 259 |  | 252 |  | 139 |  | 132
Derivatives | 210 |  | 166 |  | 115 |  | 77 |  | 95 |  | 89
Commodity cost recovery | 40 |  | 17 |  | 38 |  | 15 |  | 2 |  | 2
WPL’s West Riverside liquidated damages | 32 |  | 36 |  | — |  | — |  | 32 |  | 36
Electric transmission cost recovery | 20 |  | 51 |  | 10 |  | 27 |  | 10 |  | 24
Other | 45 |  | 32 |  | 29 |  | 8 |  | 16 |  | 24
| $1,324 |  | $1,271 |  | $754 |  | $691 |  | $570 |  | $580
WPL [Member] |
Regulatory Assets [Line Items] |
Schedule of Regulatory Assets | At December 31, regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Tax-related | $929 |  |  | $934 |  |  | $848 |  |  | $884 |  |  | $81 |  |  | $50 |
Pension and OPEB costs | 392 |  |  | 462 |  |  | 197 |  |  | 228 |  |  | 195 |  |  | 234 |
Commodity cost recovery | 160 |  |  | 42 |  |  | 1 |  |  | 2 |  |  | 159 |  |  | 40 |
AROs | 151 |  |  | 128 |  |  | 110 |  |  | 89 |  |  | 41 |  |  | 39 |
Derivatives | 84 |  |  | 8 |  |  | 48 |  |  | 4 |  |  | 36 |  |  | 4 |
Assets retired early | 70 |  |  | 92 |  |  | 53 |  |  | 66 |  |  | 17 |  |  | 26 |
IPL’s DAEC PPA amendment | 66 |  |  | 90 |  |  | 66 |  |  | 90 |  |  | — |  |  | — |
WPL’s Western Wisconsin gas distribution expansion investments | 48 |  |  | 52 |  |  | — |  |  | — |  |  | 48 |  |  | 52 |
Other | 146 |  |  | 132 |  |  | 63 |  |  | 80 |  |  | 83 |  |  | 52 |
| $2,046 |  |  | $1,940 |  |  | $1,386 |  |  | $1,443 |  |  | $660 |  |  | $497 |
Assets Retired Early | Details regarding the recovery of the remaining net book value of these assets from IPL’s and WPL’s customers are as follows (dollars in millions):
Entity |  | Asset |  | Retirement Date |  | Regulatory Asset Balance as of Dec. 31, 2022 |  | Recovery |  | Regulatory Approval
IPL |  | Sutherland Units 1 and 3 |  | 2017 |  | $16 |  | Return of and return on remaining net book value through 2027 |  | IUB and FERC
IPL |  | M.L. Kapp Unit 2 |  | 2018 |  | 13 |  | Return of and return on remaining net book value through 2029 |  | IUB and FERC
IPL |  | Analog electric meters |  | 2019 |  | 24 |  | Return of remaining net book value through 2028 |  | IUB and FERC
WPL |  | Edgewater Unit 4 |  | 2018 |  | 17 |  | Return of and return on remaining net book value through 2028 |  | PSCW and FERC
Schedule of Regulatory Liabilities | At December 31, regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Tax-related | $579 |  | $585 |  | $303 |  | $312 |  | $276 |  | $273
Cost of removal obligations | 398 |  | 384 |  | 259 |  | 252 |  | 139 |  | 132
Derivatives | 210 |  | 166 |  | 115 |  | 77 |  | 95 |  | 89
Commodity cost recovery | 40 |  | 17 |  | 38 |  | 15 |  | 2 |  | 2
WPL’s West Riverside liquidated damages | 32 |  | 36 |  | — |  | — |  | 32 |  | 36
Electric transmission cost recovery | 20 |  | 51 |  | 10 |  | 27 |  | 10 |  | 24
Other | 45 |  | 32 |  | 29 |  | 8 |  | 16 |  | 24
| $1,324 |  | $1,271 |  | $754 |  | $691 |  | $570 |  | $580

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