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Regulatory Matters (Tables) | 6 Months Ended
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Jun. 30, 2024
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2024 |  | December 31, 2023 |  | June 30, 2024 |  | December 31, 2023 |  | June 30, 2024 |  | December 31, 2023
Tax-related | $958 |  | $934 |  | $848 |  | $831 |  | $110 |  | $103
AROs | 408 |  | 194 |  | 218 |  | 160 |  | 190 |  | 34
Pension and OPEB costs | 334 |  | 347 |  | 165 |  | 171 |  | 169 |  | 176
Assets retired early | 197 |  | 273 |  | 184 |  | 259 |  | 13 |  | 14
Derivatives | 95 |  | 102 |  | 33 |  | 34 |  | 62 |  | 68
Commodity cost recovery | 89 |  | 120 |  | 2 |  | 12 |  | 87 |  | 108
WPL’s Western Wisconsin gas distribution expansion investments | 43 |  | 44 |  | — |  | — |  | 43 |  | 44
IPL’s Duane Arnold Energy Center PPA amendment | 30 |  | 42 |  | 30 |  | 42 |  | — |  | —
Other | 191 |  | 205 |  | 68 |  | 68 |  | 123 |  | 137
| $2,345 |  | $2,261 |  | $1,548 |  | $1,577 |  | $797 |  | $684
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2024 |  | December 31, 2023 |  | June 30, 2024 |  | December 31, 2023 |  | June 30, 2024 |  | December 31, 2023
Tax-related | $601 |  | $566 |  | $296 |  | $299 |  | $305 |  | $267
Cost of removal obligations | 374 |  | 366 |  | 232 |  | 242 |  | 142 |  | 124
Derivatives | 50 |  | 65 |  | 30 |  | 34 |  | 20 |  | 31
Commodity cost recovery | 51 |  | 48 |  | 16 |  | 13 |  | 35 |  | 35
Other | 60 |  | 85 |  | 44 |  | 56 |  | 16 |  | 29
| $1,136 |  | $1,130 |  | $618 |  | $644 |  | $518 |  | $486
IPL [Member] |
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2024 |  | December 31, 2023 |  | June 30, 2024 |  | December 31, 2023 |  | June 30, 2024 |  | December 31, 2023
Tax-related | $958 |  | $934 |  | $848 |  | $831 |  | $110 |  | $103
AROs | 408 |  | 194 |  | 218 |  | 160 |  | 190 |  | 34
Pension and OPEB costs | 334 |  | 347 |  | 165 |  | 171 |  | 169 |  | 176
Assets retired early | 197 |  | 273 |  | 184 |  | 259 |  | 13 |  | 14
Derivatives | 95 |  | 102 |  | 33 |  | 34 |  | 62 |  | 68
Commodity cost recovery | 89 |  | 120 |  | 2 |  | 12 |  | 87 |  | 108
WPL’s Western Wisconsin gas distribution expansion investments | 43 |  | 44 |  | — |  | — |  | 43 |  | 44
IPL’s Duane Arnold Energy Center PPA amendment | 30 |  | 42 |  | 30 |  | 42 |  | — |  | —
Other | 191 |  | 205 |  | 68 |  | 68 |  | 123 |  | 137
| $2,345 |  | $2,261 |  | $1,548 |  | $1,577 |  | $797 |  | $684
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2024 |  | December 31, 2023 |  | June 30, 2024 |  | December 31, 2023 |  | June 30, 2024 |  | December 31, 2023
Tax-related | $601 |  | $566 |  | $296 |  | $299 |  | $305 |  | $267
Cost of removal obligations | 374 |  | 366 |  | 232 |  | 242 |  | 142 |  | 124
Derivatives | 50 |  | 65 |  | 30 |  | 34 |  | 20 |  | 31
Commodity cost recovery | 51 |  | 48 |  | 16 |  | 13 |  | 35 |  | 35
Other | 60 |  | 85 |  | 44 |  | 56 |  | 16 |  | 29
| $1,136 |  | $1,130 |  | $618 |  | $644 |  | $518 |  | $486
WPL [Member] |
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2024 |  | December 31, 2023 |  | June 30, 2024 |  | December 31, 2023 |  | June 30, 2024 |  | December 31, 2023
Tax-related | $958 |  | $934 |  | $848 |  | $831 |  | $110 |  | $103
AROs | 408 |  | 194 |  | 218 |  | 160 |  | 190 |  | 34
Pension and OPEB costs | 334 |  | 347 |  | 165 |  | 171 |  | 169 |  | 176
Assets retired early | 197 |  | 273 |  | 184 |  | 259 |  | 13 |  | 14
Derivatives | 95 |  | 102 |  | 33 |  | 34 |  | 62 |  | 68
Commodity cost recovery | 89 |  | 120 |  | 2 |  | 12 |  | 87 |  | 108
WPL’s Western Wisconsin gas distribution expansion investments | 43 |  | 44 |  | — |  | — |  | 43 |  | 44
IPL’s Duane Arnold Energy Center PPA amendment | 30 |  | 42 |  | 30 |  | 42 |  | — |  | —
Other | 191 |  | 205 |  | 68 |  | 68 |  | 123 |  | 137
| $2,345 |  | $2,261 |  | $1,548 |  | $1,577 |  | $797 |  | $684
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2024 |  | December 31, 2023 |  | June 30, 2024 |  | December 31, 2023 |  | June 30, 2024 |  | December 31, 2023
Tax-related | $601 |  | $566 |  | $296 |  | $299 |  | $305 |  | $267
Cost of removal obligations | 374 |  | 366 |  | 232 |  | 242 |  | 142 |  | 124
Derivatives | 50 |  | 65 |  | 30 |  | 34 |  | 20 |  | 31
Commodity cost recovery | 51 |  | 48 |  | 16 |  | 13 |  | 35 |  | 35
Other | 60 |  | 85 |  | 44 |  | 56 |  | 16 |  | 29
| $1,136 |  | $1,130 |  | $618 |  | $644 |  | $518 |  | $486

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