XML 90 R56.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Regulatory Matters (Assets Retired Early) (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Regulatory Assets [Line Items] |  |
Regulatory assets | $ 2,274 | $ 2,261
Assets retired early [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 180 | 273
IPL [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 1,586 | 1,577
IPL [Member] | Assets retired early [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 168 | 259
IPL [Member] | Assets retired early [Member] | Lansing [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 131 |
IPL [Member] | Assets retired early [Member] | Analog Electric Meters [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 15 |
IPL [Member] | Assets retired early [Member] | Sutherland Units 1 and 3 [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 15 |
IPL [Member] | Assets retired early [Member] | M.L. Kapp Unit 2 [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 7 |
WPL [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 688 | 684
WPL [Member] | Assets retired early [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | 12 | $ 14
WPL [Member] | Assets retired early [Member] | Edgewater Unit 4 [Member] |  |
Regulatory Assets [Line Items] |  |
Regulatory assets | $ 12 |

X
- 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
Name: | us-gaap_RegulatoryAssetLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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/1943274/2147478742/980-340-50-1 + Details
Name: | us-gaap_RegulatoryAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=lnt_ElectricGeneratingUnitsRetiredEarlyMemberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=lnt_IplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=lnt_LansingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=lnt_AnalogElectricMetersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=lnt_SutherlandUnitsOneAndThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=lnt_MLKappMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=lnt_WplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=lnt_EdgewaterUnit4Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |