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Commitments And Contingencies (Tables) | 9 Months Ended
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Sep. 30, 2025
Commitments and Contingencies [Line Items] |
Other Purchase Commitments | At September 30, 2025, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but will require payment when electricity is generated by the provider, were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Natural gas | $879 |  | $489 |  | $390
Coal | 149 |  | 52 |  | 97
Other (a) | 110 |  | 52 |  | 26
| $1,138 |  | $593 |  | $513
(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2025.
MGP Site Estimated Future Costs And Recorded Liabilities | At September 30, 2025, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Range of estimated future costs | $7 |  | - | $29 |  | $5 |  | - | $18 |  | $2 |  | - | $11
Current and non-current environmental liabilities | $12 |  | $8 |  | $4
IPL [Member] |
Commitments and Contingencies [Line Items] |
Other Purchase Commitments | At September 30, 2025, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but will require payment when electricity is generated by the provider, were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Natural gas | $879 |  | $489 |  | $390
Coal | 149 |  | 52 |  | 97
Other (a) | 110 |  | 52 |  | 26
| $1,138 |  | $593 |  | $513
(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2025.
MGP Site Estimated Future Costs And Recorded Liabilities | At September 30, 2025, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Range of estimated future costs | $7 |  | - | $29 |  | $5 |  | - | $18 |  | $2 |  | - | $11
Current and non-current environmental liabilities | $12 |  | $8 |  | $4
WPL [Member] |
Commitments and Contingencies [Line Items] |
Other Purchase Commitments | At September 30, 2025, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but will require payment when electricity is generated by the provider, were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Natural gas | $879 |  | $489 |  | $390
Coal | 149 |  | 52 |  | 97
Other (a) | 110 |  | 52 |  | 26
| $1,138 |  | $593 |  | $513
(a)Includes individual commitments incurred during the normal course of business that exceeded $1 million at September 30, 2025.
MGP Site Estimated Future Costs And Recorded Liabilities | At September 30, 2025, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Range of estimated future costs | $7 |  | - | $29 |  | $5 |  | - | $18 |  | $2 |  | - | $11
Current and non-current environmental liabilities | $12 |  | $8 |  | $4

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- Definition Tabular disclosure of material liabilities for remediation, site restoration, postclosure, monitoring commitments, or other exit costs that may occur on the sale, disposal or abandonment of a property as a result of unanticipated contamination of the assets. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 275 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482861/275-10-50-9 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 5.Y.Q4) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480102/450-20-S99-1 + Details
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- 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 No definition available. + Details
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- Definition Tabular disclosure of key provisions of an arrangement under which the entity has agreed to purchase goods or services over a period of time greater than one year or the normal operating cycle, if longer, including the item for which expenditures will be made, minimum quantities, milestones, time period and committed amount. + References No definition available. + Details
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