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Regulatory Matters (Regulatory Assets) (Details) - USD ($) $ in Millions | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Regulatory Assets [Line Items] |  |
Regulatory assets | $ 2,046 | $ 1,940
Tax-related [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 929 | 934
Pension and OPEB costs [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 392 | 462
Commodity cost recovery [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 160 | 42
AROs [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 151 | 128
Derivatives [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 84 | 8
Assets retired early [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 70 | 92
IPL's DAEC PPA amendment [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 66 | 90
WPL's Western Wisconsin gas distribution expansion investments [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 48 | 52
Other [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 146 | 132
IPL [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 1,386 | 1,443
IPL [Member] | Tax-related [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 848 | 884
IPL [Member] | Pension and OPEB costs [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 197 | 228
IPL [Member] | Commodity cost recovery [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 1 | 2
IPL [Member] | AROs [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 110 | 89
IPL [Member] | Derivatives [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 48 | 4
IPL [Member] | Assets retired early [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 53 | 66
IPL [Member] | IPL's DAEC PPA amendment [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 66 | 90
IPL [Member] | Other [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 63 | 80
WPL [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 660 | 497
WPL [Member] | Tax-related [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 81 | 50
WPL [Member] | Pension and OPEB costs [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 195 | 234
WPL [Member] | Commodity cost recovery [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 159 | 40
WPL [Member] | AROs [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 41 | 39
WPL [Member] | Derivatives [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 36 | 4
WPL [Member] | Assets retired early [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 17 | 26
WPL [Member] | WPL's Western Wisconsin gas distribution expansion investments [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 48 | 52
WPL [Member] | Other [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | $ 83 | $ 52

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