XML 93 R59.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Property, Plant and Equipment (Property, Plant and Equipment) (Details) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2024 USD ($) MW | Dec. 31, 2023 USD ($)
Property, Plant and Equipment [Line Items] |  |
Electric plant anticipated to be retired early | $ 784,000,000 | $ 1,629,000,000
Total electric plant | 20,346,000,000 | 18,690,000,000
Gas plant in service | 1,863,000,000 | 1,791,000,000
Other plant in service | 734,000,000 | 653,000,000
Accumulated depreciation | (6,229,000,000) | (5,924,000,000)
Net plant | 16,714,000,000 | 15,210,000,000
Leased land for solar generation, net | 189,000,000 | 172,000,000
Construction work in progress | 1,215,000,000 | 1,245,000,000
Other, net | 5,000,000 | 7,000,000
Total utility | 18,123,000,000 | 16,634,000,000
Non-utility Generation, net | 103,000,000 | 68,000,000
Corporate Services and other, net | 475,000,000 | 455,000,000
Total non-utility and other | 578,000,000 | 523,000,000
Total property, plant and equipment | 18,701,000,000 | 17,157,000,000
Non-utility Generation, accumulated depreciation | 78,000,000 | 75,000,000
Corporate Services and other, accumulated depreciation | 289,000,000 | 275,000,000
Generation [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Electric plant in service | 11,156,000,000 | 9,180,000,000
Distribution [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Electric plant in service | 7,811,000,000 | 7,314,000,000
Other [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Electric plant in service | 595,000,000 | 567,000,000
IPL [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Electric plant anticipated to be retired early | 0 | 0
Total electric plant | 10,653,000,000 | 9,472,000,000
Gas plant in service | 981,000,000 | 951,000,000
Other plant in service | 456,000,000 | 411,000,000
Accumulated depreciation | (3,360,000,000) | (3,180,000,000)
Net plant | 8,730,000,000 | 7,654,000,000
Leased land for solar generation, net | 53,000,000 | 33,000,000
Construction work in progress | 548,000,000 | 605,000,000
Other, net | 5,000,000 | 6,000,000
Total utility | 9,336,000,000 | 8,298,000,000
Total property, plant and equipment | $ 9,336,000,000 | 8,298,000,000
Electric capacity of solar project | MW | 400 |
Construction project cost target exceedance | $ 1,837.5 |
Construction project cost target | $ 1,650 |
Base return on equity, percentage | 10.25% |
IPL [Member] | Generation [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Electric plant in service | $ 5,924,000,000 | 5,025,000,000
IPL [Member] | Distribution [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Electric plant in service | 4,344,000,000 | 4,091,000,000
IPL [Member] | Other [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Electric plant in service | 385,000,000 | 356,000,000
WPL [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Electric plant anticipated to be retired early | 784,000,000 | 1,629,000,000
Total electric plant | 9,693,000,000 | 9,218,000,000
Gas plant in service | 882,000,000 | 840,000,000
Other plant in service | 278,000,000 | 242,000,000
Accumulated depreciation | (2,869,000,000) | (2,744,000,000)
Net plant | 7,984,000,000 | 7,556,000,000
Leased Sheboygan Falls Energy Facility, net | 74,000,000 | 79,000,000
Leased land for solar generation, net | 136,000,000 | 139,000,000
Construction work in progress | 667,000,000 | 640,000,000
Other, net | 0 | 1,000,000
Total utility | 8,861,000,000 | 8,415,000,000
Total property, plant and equipment | $ 8,861,000,000 | 8,415,000,000
Electric capacity of solar project | MW | 1,100 |
Construction project cost target exceedance | $ 205,000,000 |
Leased Sheboygan Falls Energy Facility, accumulated depreciation | 116,000,000 | 112,000,000
WPL [Member] | Columbia Units 1-2 [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Electric plant anticipated to be retired early | 413,000,000 | 428,000,000
WPL [Member] | Generation [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Electric plant in service | 5,232,000,000 | 4,155,000,000
WPL [Member] | Distribution [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Electric plant in service | 3,467,000,000 | 3,223,000,000
WPL [Member] | Other [Member] |  |
Property, Plant and Equipment [Line Items] |  |
Electric plant in service | $ 210,000,000 | $ 211,000,000

X
- Definition Accumulated Amortization On Public Utilities Property Plant And Equipment Leased + References No definition available. + Details
Name: | lnt_AccumulatedAmortizationOnPublicUtilitiesPropertyPlantAndEquipmentLeased
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Accumulated Depreciation on Property Plant and Equipment Non-regulated Generation. + References No definition available. + Details
Name: | lnt_AccumulatedDepreciationOnPropertyPlantAndEquipmentNonRegulatedBusinessLine1
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Accumulated Depreciation on Property Plant and Equipment Alliant Energy Corporate Services, Inc. and other. + References No definition available. + Details
Name: | lnt_AccumulatedDepreciationOnPropertyPlantAndEquipmentNonRegulatedBusinessLine2
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Construction Project Cost Target + References No definition available. + Details
Name: | lnt_ConstructionProjectCostTarget
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Construction Project Cost Target Exceedance + References No definition available. + Details
Name: | lnt_ConstructionProjectCostTargetExceedance
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Electric Capacity of Solar Project + References No definition available. + Details
Name: | lnt_ElectricCapacityOfSolarProject
Namespace Prefix: | lnt_
Data Type: | dtr-types1:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Tangible assets that are held by an entity for use in the production or supply of utilities and that are expected to provide economic benefit for more than one year; net of accumulated depreciation. + References No definition available. + Details
Name: | lnt_NetUtilityPlant
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Carrying amount as of the balance sheet date of long-lived, depreciable Non-regulated Generation plant. + References No definition available. + Details
Name: | lnt_PropertyPlantAndEquipmentNonregulatedBusinessLine1
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Carrying amount as of the balance sheet date of long-lived, depreciable Alliant Energy Corporate Services, Inc. and other plant. + References No definition available. + Details
Name: | lnt_PropertyPlantAndEquipmentNonregulatedBusinessLine2
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Carrying amount as of the balance sheet date of long-lived, depreciable electric utility plant. + References No definition available. + Details
Name: | lnt_PublicUtilitiesPropertyPlantAndEquipmentElectric
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Carrying amount as of the balance sheet date of long-lived, depreciable gas utility plant. + References No definition available. + Details
Name: | lnt_PublicUtilitiesPropertyPlantAndEquipmentGas
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Carrying amount as of the balance sheet date of long-lived, depreciable general utility plant. + References No definition available. + Details
Name: | lnt_PublicUtilitiesPropertyPlantAndEquipmentGeneral
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Public Utilities, Property Plant And Equipment Leased + References No definition available. + Details
Name: | lnt_PublicUtilitiesPropertyPlantAndEquipmentLeased
Namespace Prefix: | lnt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, after accumulated depreciation and amortization, of property, plant, and equipment and finance lease right-of-use asset. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 360 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482099/360-10-50-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a) -SubTopic 20 -Topic 842 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-4 + Details
Name: | us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 7A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-7A + Details
Name: | us-gaap_PropertyPlantAndEquipmentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -SubTopic 10 -Topic 360 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482099/360-10-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 7A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-7A Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 852 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481372/852-10-55-10 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(8)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 360 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478451/942-360-50-1 + Details
Name: | us-gaap_PropertyPlantAndEquipmentNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before accumulated depreciation, depletion and amortization of other physical assets used in the normal conduct of business to produce goods and services and not intended for resale. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 1 -SubTopic 10 -Topic 360 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482099/360-10-50-1 + Details
Name: | us-gaap_PropertyPlantAndEquipmentOther
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Percentage of public utility's approved return on equity. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period end book value of accumulated depreciation on property, plant and equipment (PPE) that is owned by the regulated operations of the public utility. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Period end amount of construction work in progress in public utility. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Period end amount of total net PPE. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Period end book value of other property, plant and equipment (PPE) owned (but not classified elsewhere) by the public utility. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Period end amount of total gross PPE. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPlantInService
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The present value amount of future cost recoveries that are probable and estimable related to plant abandonment's for regulated industries. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section 35 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478654/980-360-35-3 + Details
Name: | us-gaap_PublicUtilitiesPropertyPlantAndEquipmentPresentValueOfRegulatedAssetForPlantAbandonment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

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

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=lnt_ColumbiaUnits1And2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |