XML 114 R80.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Leases (Finance Lease) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | $ 189 | $ 172 |
Finance lease liabilities, Other current liabilities | 0 | 0 |
Finance lease liabilities, Other liabilities | 189 | 172 |
Finance lease liabilities, Total | $ 189 | $ 172 |
Finance lease, Remaining lease term | 31 years | 33 years |
Finance lease, Discount rate, percent | 5.00% | 5.00% |
Finance lease, Depreciation expense | $ 0 | $ 1 | $ 0
Finance lease, Interest expense | 8 | 6 | 3
Finance lease, Total expense | $ 8 | $ 7 | 3
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] | Property, plant and equipment, net | Property, plant and equipment, net |
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] | Other | Other |
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] | Other | Other |
Sheboygan Falls Energy Facility [Member] |  |  |
Leases [Line Items] |  |  |
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] | Property, plant and equipment, net | Property, plant and equipment, net |
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] | Other | Other |
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] | Other | Other |
Leased land for solar generation [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | $ 189 | $ 172 |
Finance lease liabilities, Other current liabilities | 0 | 0 |
Finance lease liabilities, Other liabilities | $ 189 | $ 172 |
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] | Property, plant and equipment, net | Property, plant and equipment, net |
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] | Other | Other |
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] | Other | Other |
IPL [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | $ 53 | $ 33 |
Finance lease liabilities, Other current liabilities | 0 | 0 |
Finance lease liabilities, Other liabilities | 53 | 33 |
Finance lease liabilities, Total | $ 53 | $ 33 |
Finance lease, Remaining lease term | 28 years | 29 years |
Finance lease, Discount rate, percent | 5.00% | 5.00% |
Finance lease, Depreciation expense | $ 0 | $ 0 | 0
Finance lease, Interest expense | 2 | 1 | 0
Finance lease, Total expense | 2 | 1 | 0
IPL [Member] | Leased land for solar generation [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | 53 | 33 |
Finance lease liabilities, Other current liabilities | 0 | 0 |
Finance lease liabilities, Other liabilities | 53 | 33 |
WPL [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | 210 | 218 |
Finance lease liabilities, Other current liabilities | 7 | 11 |
Finance lease liabilities, Other liabilities | 207 | 217 |
Finance lease liabilities, Total | $ 214 | $ 228 |
Finance lease, Remaining lease term | 28 years | 27 years |
Finance lease, Discount rate, percent | 5.00% | 5.00% |
Finance lease, Depreciation expense | $ 4 | $ 6 | 6
Finance lease, Interest expense | 10 | 8 | 7
Finance lease, Total expense | 14 | 14 | $ 13
WPL [Member] | Sheboygan Falls Energy Facility [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | 74 | 79 |
Finance lease liabilities, Other current liabilities | 7 | 11 |
Finance lease liabilities, Other liabilities | 71 | 78 |
WPL [Member] | Leased land for solar generation [Member] |  |  |
Leases [Line Items] |  |  |
Finance lease assets, Property, plant and equipment, net | 136 | 139 |
Finance lease liabilities, Other current liabilities | 0 | 0 |
Finance lease liabilities, Other liabilities | $ 136 | $ 139 |

X
- Definition Amount of interest expense on finance lease liability. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 53 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479589/842-20-55-53 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 4 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479041/842-20-45-4 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-4 + Details
Name: | us-gaap_FinanceLeaseInterestExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Present value of lessee's discounted obligation for lease payments from finance lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-6 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479041/842-20-45-1 + Details
Name: | us-gaap_FinanceLeaseLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Present value of lessee's discounted obligation for lease payments from finance lease, classified as current. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479041/842-20-45-1 + Details
Name: | us-gaap_FinanceLeaseLiabilityCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Indicates line item in statement of financial position that includes current finance lease liability. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479041/842-20-45-2 + Details
Name: | us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList
Namespace Prefix: | us-gaap_
Data Type: | enum2:enumerationSetItemType
Balance Type: | na
Period Type: | instant

X
- Definition Present value of lessee's discounted obligation for lease payments from finance lease, classified as noncurrent. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479041/842-20-45-1 + Details
Name: | us-gaap_FinanceLeaseLiabilityNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Indicates line item in statement of financial position that includes noncurrent finance lease liability. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479041/842-20-45-2 + Details
Name: | us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList
Namespace Prefix: | us-gaap_
Data Type: | enum2:enumerationSetItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount, after accumulated amortization, of right-of-use asset from finance lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479041/842-20-45-1 + Details
Name: | us-gaap_FinanceLeaseRightOfUseAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of amortization expense attributable to right-of-use asset from finance lease. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 53 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479589/842-20-55-53 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 4 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479041/842-20-45-4 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-4 + Details
Name: | us-gaap_FinanceLeaseRightOfUseAssetAmortization
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Indicates line item in statement of financial position that includes finance lease right-of-use asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479041/842-20-45-2 + Details
Name: | us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList
Namespace Prefix: | us-gaap_
Data Type: | enum2:enumerationSetItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average discount rate for finance lease calculated at point in time. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 53 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479589/842-20-55-53 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (g)(4) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-4 + Details
Name: | us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average remaining lease term for finance lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 53 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479589/842-20-55-53 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (g)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-4 + Details
Name: | us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of lease cost recognized by lessee for lease contract. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 53 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479589/842-20-55-53 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-4 + Details
Name: | us-gaap_LeaseCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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 (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-7A Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-3 + Details
Name: | us-gaap_LesseeLeaseDescriptionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=lnt_LeasedLandForSolarGenerationMember
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: |