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Regulatory Matters (Assets Retired Early) (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022
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Regulatory Assets [Line Items] |  |
Regulatory assets | $ 2,261 | $ 2,046
Assets retired early [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 273 | 70
IPL [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 1,577 | 1,386
IPL [Member] | Assets retired early [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 259 | 53
IPL [Member] | Assets retired early [Member] | Lansing [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 216 |
IPL [Member] | Assets retired early [Member] | Analog Electric Meters [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 20 |
IPL [Member] | Assets retired early [Member] | Sutherland Units 1 and 3 [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 12 |
IPL [Member] | Assets retired early [Member] | M.L. Kapp Unit 2 [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 11 |
WPL [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 684 | 660
WPL [Member] | Assets retired early [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 14 | $ 17
WPL [Member] | Assets retired early [Member] | Edgewater Unit 4 [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | $ 14 |

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- Definition The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 340 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481878/980-340-50-1 + Details
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