XML 71 R51.htm IDEA: XBRL DOCUMENT
v3.25.3

Revenue (Disaggregation of Revenues) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | $ 1,210 | $ 1,081 | $ 3,298 | $ 3,005
Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 1,124 | 999 | 2,828 | 2,579
Electric [Member] | Retail - residential [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 408 | 378 | 1,027 | 966
Electric [Member] | Retail - commercial [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 282 | 239 | 705 | 616
Electric [Member] | Retail - industrial [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 306 | 270 | 782 | 730
Electric [Member] | Wholesale [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 51 | 58 | 148 | 147
Electric [Member] | Other [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 77 | 54 | 166 | 120
Gas [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 51 | 49 | 366 | 322
Gas [Member] | Retail - residential [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 24 | 24 | 211 | 189
Gas [Member] | Retail - commercial [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 13 | 13 | 106 | 92
Gas [Member] | Retail - industrial [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 1 | 1 | 10 | 8
Gas [Member] | Other [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 13 | 11 | 39 | 33
Other Utility [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 12 | 12 | 37 | 36
Other Utility [Member] | Steam [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 9 | 9 | 28 | 29
Other Utility [Member] | Other [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 3 | 3 | 9 | 7
Non-Utility and Other [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 23 | 21 | 67 | 68
Non-Utility and Other [Member] | Other [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 23 | 21 | 67 | 68
IPL [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 647 | 561 | 1,676 | 1,527
IPL [Member] | Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 608 | 523 | 1,455 | 1,318
IPL [Member] | Electric [Member] | Retail - residential [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 215 | 202 | 512 | 502
IPL [Member] | Electric [Member] | Retail - commercial [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 192 | 153 | 462 | 385
IPL [Member] | Electric [Member] | Retail - industrial [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 167 | 142 | 403 | 372
IPL [Member] | Electric [Member] | Wholesale [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 11 | 19 | 39 | 45
IPL [Member] | Electric [Member] | Other [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 23 | 7 | 39 | 14
IPL [Member] | Gas [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 27 | 27 | 185 | 175
IPL [Member] | Gas [Member] | Retail - residential [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 12 | 13 | 107 | 103
IPL [Member] | Gas [Member] | Retail - commercial [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 7 | 7 | 49 | 48
IPL [Member] | Gas [Member] | Retail - industrial [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 1 | 1 | 6 | 5
IPL [Member] | Gas [Member] | Other [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 7 | 6 | 23 | 19
IPL [Member] | Other Utility [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 12 | 11 | 36 | 34
IPL [Member] | Other Utility [Member] | Steam [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 9 | 9 | 28 | 29
IPL [Member] | Other Utility [Member] | Other [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 3 | 2 | 8 | 5
WPL [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 540 | 499 | 1,555 | 1,410
WPL [Member] | Electric [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 516 | 476 | 1,373 | 1,261
WPL [Member] | Electric [Member] | Retail - residential [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 193 | 176 | 515 | 464
WPL [Member] | Electric [Member] | Retail - commercial [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 90 | 86 | 243 | 231
WPL [Member] | Electric [Member] | Retail - industrial [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 139 | 128 | 379 | 358
WPL [Member] | Electric [Member] | Wholesale [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 40 | 39 | 109 | 102
WPL [Member] | Electric [Member] | Other [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 54 | 47 | 127 | 106
WPL [Member] | Gas [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 24 | 22 | 181 | 147
WPL [Member] | Gas [Member] | Retail - residential [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 12 | 11 | 104 | 86
WPL [Member] | Gas [Member] | Retail - commercial [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 6 | 6 | 57 | 44
WPL [Member] | Gas [Member] | Retail - industrial [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 0 | 0 | 4 | 3
WPL [Member] | Gas [Member] | Other [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 6 | 5 | 16 | 14
WPL [Member] | Other Utility [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | 0 | 1 | 1 | 2
WPL [Member] | Other Utility [Member] | Other [Member] |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenue from contracts with customers | $ 0 | $ 1 | $ 1 | $ 2

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 606 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-7 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-5 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 91 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479777/606-10-55-91 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 91 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479777/606-10-55-91 Reference 5: http://www.xbrl.org/2003/role/exampleRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 91 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479777/606-10-55-91 Reference 6: http://www.xbrl.org/2003/role/exampleRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 91 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479777/606-10-55-91 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 91 -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479777/606-10-55-91 Reference 8: http://www.xbrl.org/2003/role/exampleRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 91 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479777/606-10-55-91 Reference 9: http://www.xbrl.org/2003/role/exampleRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 91 -Subparagraph (g) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479777/606-10-55-91 + Details
Name: | us-gaap_DisaggregationOfRevenueLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-4 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-14 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 41 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-41 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 42 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-42 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-7 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 270 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482964/270-10-50-1 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 32 -Subparagraph (ee) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-32 Reference 8: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 32 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-32 Reference 9: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 32 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-32 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 924 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 11.L) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479941/924-10-S99-1 Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-5 Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 30 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-30 Reference 13: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 22 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-22 Reference 14: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 40 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-40 Reference 15: http://www.xbrl.org/2003/role/disclosureRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 22 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-22 Reference 16: http://www.xbrl.org/2003/role/disclosureRef -Topic 606 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479806/606-10-50-4 + Details
Name: | us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=lnt_ElectricMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=lnt_RetailResidentialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=lnt_RetailCommercialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=lnt_RetailIndustrialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=lnt_WholesaleMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=us-gaap_OtherCustomerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=lnt_GasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=lnt_OtherUtilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=lnt_SteamMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=us-gaap_AllOtherSegmentsMember
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: |