XML 57 R37.htm IDEA: XBRL DOCUMENT
v3.25.3

Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Regulatory Matters [Line Items] |  |  |  |
Asset valuation charge for IPL's Lansing Generating Station | $ 0 | $ 0 | $ 0 | $ 60
IPL [Member] |  |  |  |
Regulatory Matters [Line Items] |  |  |  |
Asset valuation charge for IPL's Lansing Generating Station | $ 0 | $ 0 | $ 0 | $ 60

X
- Definition Regulatory Matters [Line Items] + References No definition available. + Details
Name: | lnt_RegulatoryMattersLineItems
Namespace Prefix: | lnt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-28 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 942 -SubTopic 10 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480095/942-10-S50-1 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 942 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480035/942-10-S99-6 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482130/360-10-45-4 + Details
Name: | us-gaap_AssetImpairmentCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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