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Income Taxes (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2022 | Sep. 30, 2021 | Dec. 31, 2024 | Dec. 31, 2023
Income Taxes [Line Items] |  |  |  |  |  |
State income tax rate, percent |  |  | 9.80% |  |  |
Regulatory assets |  |  | $ (102) | $ (21) |  |
Income tax expense (benefit) | $ 14 | $ (21) | 26 | (66) |  |
Tax-related [Member] |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |
Regulatory assets | 76 |  |  |  |  |
Income tax expense (benefit) | 8 |  |  |  |  |
Forecast [Member] |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |
State income tax rate, percent |  |  |  |  | 5.50% | 8.40%
IPL [Member] |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |
Regulatory assets |  |  | 18 | (33) |  |
Income tax expense (benefit) | (16) | (12) | (39) | (34) |  |
IPL [Member] | Tax-related [Member] |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |
Regulatory assets | 76 |  |  |  |  |
WPL [Member] |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |
Regulatory assets |  |  | (120) | 11 |  |
Income tax expense (benefit) | $ 16 | $ (15) | $ 50 | $ (41) |  |

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- Definition Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 6.I.Fact.4) -URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32687-109319 + Details
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