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Regulatory Matters (Tables) | 6 Months Ended
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Jun. 30, 2022
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2022 |  | December 31, 2021 |  | June 30, 2022 |  | December 31, 2021 |  | June 30, 2022 |  | December 31, 2021
Tax-related | $954 |  | $934 |  | $903 |  | $884 |  | $51 |  | $50
Pension and OPEB costs | 445 |  | 462 |  | 220 |  | 228 |  | 225 |  | 234
Asset retirement obligations | 140 |  | 128 |  | 99 |  | 89 |  | 41 |  | 39
Derivatives | 101 |  | 8 |  | 69 |  | 4 |  | 32 |  | 4
Commodity cost recovery | 88 |  | 42 |  | 2 |  | 2 |  | 86 |  | 40
Assets retired early | 82 |  | 92 |  | 61 |  | 66 |  | 21 |  | 26
IPL’s DAEC PPA amendment | 78 |  | 90 |  | 78 |  | 90 |  | — |  | —
WPL’s Western Wisconsin gas distribution expansion investments | 50 |  | 52 |  | — |  | — |  | 50 |  | 52
Other | 113 |  | 132 |  | 58 |  | 80 |  | 55 |  | 52
| $2,051 |  | $1,940 |  | $1,490 |  | $1,443 |  | $561 |  | $497
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2022 |  | December 31, 2021 |  | June 30, 2022 |  | December 31, 2021 |  | June 30, 2022 |  | December 31, 2021
Tax-related | $573 |  | $585 |  | $308 |  | $312 |  | $265 |  | $273
Cost of removal obligations | 396 |  | 384 |  | 258 |  | 252 |  | 138 |  | 132
Derivatives | 288 |  | 166 |  | 153 |  | 77 |  | 135 |  | 89
WPL’s West Riverside liquidated damages | 34 |  | 36 |  | — |  | — |  | 34 |  | 36
Electric transmission cost recovery | 31 |  | 51 |  | 11 |  | 27 |  | 20 |  | 24
Other | 41 |  | 49 |  | 21 |  | 23 |  | 20 |  | 26
| $1,363 |  | $1,271 |  | $751 |  | $691 |  | $612 |  | $580
IPL [Member] |
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2022 |  | December 31, 2021 |  | June 30, 2022 |  | December 31, 2021 |  | June 30, 2022 |  | December 31, 2021
Tax-related | $954 |  | $934 |  | $903 |  | $884 |  | $51 |  | $50
Pension and OPEB costs | 445 |  | 462 |  | 220 |  | 228 |  | 225 |  | 234
Asset retirement obligations | 140 |  | 128 |  | 99 |  | 89 |  | 41 |  | 39
Derivatives | 101 |  | 8 |  | 69 |  | 4 |  | 32 |  | 4
Commodity cost recovery | 88 |  | 42 |  | 2 |  | 2 |  | 86 |  | 40
Assets retired early | 82 |  | 92 |  | 61 |  | 66 |  | 21 |  | 26
IPL’s DAEC PPA amendment | 78 |  | 90 |  | 78 |  | 90 |  | — |  | —
WPL’s Western Wisconsin gas distribution expansion investments | 50 |  | 52 |  | — |  | — |  | 50 |  | 52
Other | 113 |  | 132 |  | 58 |  | 80 |  | 55 |  | 52
| $2,051 |  | $1,940 |  | $1,490 |  | $1,443 |  | $561 |  | $497
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2022 |  | December 31, 2021 |  | June 30, 2022 |  | December 31, 2021 |  | June 30, 2022 |  | December 31, 2021
Tax-related | $573 |  | $585 |  | $308 |  | $312 |  | $265 |  | $273
Cost of removal obligations | 396 |  | 384 |  | 258 |  | 252 |  | 138 |  | 132
Derivatives | 288 |  | 166 |  | 153 |  | 77 |  | 135 |  | 89
WPL’s West Riverside liquidated damages | 34 |  | 36 |  | — |  | — |  | 34 |  | 36
Electric transmission cost recovery | 31 |  | 51 |  | 11 |  | 27 |  | 20 |  | 24
Other | 41 |  | 49 |  | 21 |  | 23 |  | 20 |  | 26
| $1,363 |  | $1,271 |  | $751 |  | $691 |  | $612 |  | $580
WPL [Member] |
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2022 |  | December 31, 2021 |  | June 30, 2022 |  | December 31, 2021 |  | June 30, 2022 |  | December 31, 2021
Tax-related | $954 |  | $934 |  | $903 |  | $884 |  | $51 |  | $50
Pension and OPEB costs | 445 |  | 462 |  | 220 |  | 228 |  | 225 |  | 234
Asset retirement obligations | 140 |  | 128 |  | 99 |  | 89 |  | 41 |  | 39
Derivatives | 101 |  | 8 |  | 69 |  | 4 |  | 32 |  | 4
Commodity cost recovery | 88 |  | 42 |  | 2 |  | 2 |  | 86 |  | 40
Assets retired early | 82 |  | 92 |  | 61 |  | 66 |  | 21 |  | 26
IPL’s DAEC PPA amendment | 78 |  | 90 |  | 78 |  | 90 |  | — |  | —
WPL’s Western Wisconsin gas distribution expansion investments | 50 |  | 52 |  | — |  | — |  | 50 |  | 52
Other | 113 |  | 132 |  | 58 |  | 80 |  | 55 |  | 52
| $2,051 |  | $1,940 |  | $1,490 |  | $1,443 |  | $561 |  | $497
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| June 30, 2022 |  | December 31, 2021 |  | June 30, 2022 |  | December 31, 2021 |  | June 30, 2022 |  | December 31, 2021
Tax-related | $573 |  | $585 |  | $308 |  | $312 |  | $265 |  | $273
Cost of removal obligations | 396 |  | 384 |  | 258 |  | 252 |  | 138 |  | 132
Derivatives | 288 |  | 166 |  | 153 |  | 77 |  | 135 |  | 89
WPL’s West Riverside liquidated damages | 34 |  | 36 |  | — |  | — |  | 34 |  | 36
Electric transmission cost recovery | 31 |  | 51 |  | 11 |  | 27 |  | 20 |  | 24
Other | 41 |  | 49 |  | 21 |  | 23 |  | 20 |  | 26
| $1,363 |  | $1,271 |  | $751 |  | $691 |  | $612 |  | $580

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