XML 113 R79.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Leases (Operating Leases) (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Leases [Line Items] |  |
Operating leases assets, Property, plant and equipment, net | $ 22 | $ 23
Operating leases liabilities, Other current liabilities | 2 | 2
Operating leases liabilities, Other liabilities | 20 | 21
Operating leases liabilities, Total | $ 22 | $ 23
Operating leases, Weighted average remaining lease term | 11 years | 12 years
Operating leases, Weighted average discount rate, percent | 4.00% | 4.00%
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] | Property, plant and equipment, net | Property, plant and equipment, net
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] | Other | Other
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List] | Other | Other
IPL [Member] |  |
Leases [Line Items] |  |
Operating leases assets, Property, plant and equipment, net | $ 12 | $ 13
Operating leases liabilities, Other current liabilities | 1 | 1
Operating leases liabilities, Other liabilities | 11 | 12
Operating leases liabilities, Total | $ 12 | $ 13
Operating leases, Weighted average remaining lease term | 11 years | 12 years
Operating leases, Weighted average discount rate, percent | 4.00% | 4.00%
WPL [Member] |  |
Leases [Line Items] |  |
Operating leases assets, Property, plant and equipment, net | $ 9 | $ 9
Operating leases liabilities, Other current liabilities | 1 | 1
Operating leases liabilities, Other liabilities | 8 | 8
Operating leases liabilities, Total | $ 9 | $ 9
Operating leases, Weighted average remaining lease term | 12 years | 12 years
Operating leases, Weighted average discount rate, percent | 4.00% | 4.00%

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
- Definition Discount rate used by lessee to determine present value of operating lease payments. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 842 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478964/842-20-50-3 + Details
Name: | us-gaap_LesseeOperatingLeaseDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Present value of lessee's discounted obligation for lease payments from operating lease. + 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_OperatingLeaseLiability
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 operating 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_OperatingLeaseLiabilityCurrent
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 operating 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_OperatingLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList
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 operating 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_OperatingLeaseLiabilityNoncurrent
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 operating 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_OperatingLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList
Namespace Prefix: | us-gaap_
Data Type: | enum2:enumerationSetItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of lessee's right to use underlying asset under operating 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_OperatingLeaseRightOfUseAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Indicates line item in statement of financial position that includes operating 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_OperatingLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList
Namespace Prefix: | us-gaap_
Data Type: | enum2:enumerationSetItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average remaining lease term for operating 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_OperatingLeaseWeightedAverageRemainingLeaseTerm1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

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: |