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Regulatory Matters (Regulatory Liabilities) (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | $ 1,130.0 | $ 1,324.0
Tax-related [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 566.0 | 579.0
Cost of removal obligations [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 366.0 | 398.0
Derivatives [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 65.0 | 210.0
Commodity cost recovery [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 48.0 | 40.0
West Riverside liquidated damages [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 1.0 | 32.0
Other [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 84.0 | 65.0
IPL [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 644.0 | 754.0
IPL [Member] | Tax-related [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 299.0 | 303.0
IPL [Member] | Cost of removal obligations [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 242.0 | 259.0
IPL [Member] | Derivatives [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 34.0 | 115.0
IPL [Member] | Commodity cost recovery [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 13.0 | 38.0
IPL [Member] | Other [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 56.0 | 39.0
WPL [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 486.0 | 570.0
WPL [Member] | Tax-related [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 267.0 | 276.0
WPL [Member] | Cost of removal obligations [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 124.0 | 139.0
WPL [Member] | Derivatives [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 31.0 | 95.0
WPL [Member] | Commodity cost recovery [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 35.0 | 2.0
WPL [Member] | West Riverside liquidated damages [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | 1.0 | 32.0
WPL [Member] | Other [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities | $ 28.0 | $ 26.0

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- Definition The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 405 -Name Accounting Standards Codification -Section 25 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481854/980-405-25-1 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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