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Asset Retirement Obligations | 6 Months Ended
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Jun. 30, 2024
Asset Retirement Obligations [Line Items] |
Asset Retirement Obligations | ASSET RETIREMENT OBLIGATIONS A reconciliation of the changes in AROs associated with long-lived assets for the six months ended June 30, 2024 is as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Balance, January 1 | $246 |  | $148 |  | $98
Revisions in estimated cash flows | (2) |  | — |  | (2)
Liabilities settled | (1) |  | — |  | (1)
Liabilities incurred (a) | 355 |  | 102 |  | 253
Accretion expense | 5 |  | 3 |  | 2
Balance, June 30 | $603 |  | $253 |  | $350
(a)In the second quarter of 2024, substantially due to the enactment of the revised CCR Rule, which significantly expands the scope of regulation to include coal ash ponds at sites that no longer produce electricity and inactive landfills, including some IPL and WPL facilities, Alliant Energy, IPL and WPL recorded additional AROs, additional ARO regulatory assets for EGUs no longer in operation, additional property, plant and equipment for EGUs still in operation, and a pre-tax non-cash charge of $20 million recorded to “Other operation and maintenance” in Alliant Energy’s and IPL’s income statements for the portion allocated to IPL’s steam business for IPL’s Prairie Creek Generating Station and the retired Sixth Street Generating Station as established in prior rate reviews. The amounts recorded in the second quarter of 2024 are expected to be adjusted in the future as additional information is obtained for the specific site closure plans, including the determination of whether or not individual sites are considered legal obligations and the acceptance and approval of compliance approaches, which could change management assumptions and result in a material change to the recorded amounts.
IPL [Member] |
Asset Retirement Obligations [Line Items] |
Asset Retirement Obligations | ASSET RETIREMENT OBLIGATIONS A reconciliation of the changes in AROs associated with long-lived assets for the six months ended June 30, 2024 is as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Balance, January 1 | $246 |  | $148 |  | $98
Revisions in estimated cash flows | (2) |  | — |  | (2)
Liabilities settled | (1) |  | — |  | (1)
Liabilities incurred (a) | 355 |  | 102 |  | 253
Accretion expense | 5 |  | 3 |  | 2
Balance, June 30 | $603 |  | $253 |  | $350
(a)In the second quarter of 2024, substantially due to the enactment of the revised CCR Rule, which significantly expands the scope of regulation to include coal ash ponds at sites that no longer produce electricity and inactive landfills, including some IPL and WPL facilities, Alliant Energy, IPL and WPL recorded additional AROs, additional ARO regulatory assets for EGUs no longer in operation, additional property, plant and equipment for EGUs still in operation, and a pre-tax non-cash charge of $20 million recorded to “Other operation and maintenance” in Alliant Energy’s and IPL’s income statements for the portion allocated to IPL’s steam business for IPL’s Prairie Creek Generating Station and the retired Sixth Street Generating Station as established in prior rate reviews. The amounts recorded in the second quarter of 2024 are expected to be adjusted in the future as additional information is obtained for the specific site closure plans, including the determination of whether or not individual sites are considered legal obligations and the acceptance and approval of compliance approaches, which could change management assumptions and result in a material change to the recorded amounts.
WPL [Member] |
Asset Retirement Obligations [Line Items] |
Asset Retirement Obligations | ASSET RETIREMENT OBLIGATIONS A reconciliation of the changes in AROs associated with long-lived assets for the six months ended June 30, 2024 is as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Balance, January 1 | $246 |  | $148 |  | $98
Revisions in estimated cash flows | (2) |  | — |  | (2)
Liabilities settled | (1) |  | — |  | (1)
Liabilities incurred (a) | 355 |  | 102 |  | 253
Accretion expense | 5 |  | 3 |  | 2
Balance, June 30 | $603 |  | $253 |  | $350
(a)In the second quarter of 2024, substantially due to the enactment of the revised CCR Rule, which significantly expands the scope of regulation to include coal ash ponds at sites that no longer produce electricity and inactive landfills, including some IPL and WPL facilities, Alliant Energy, IPL and WPL recorded additional AROs, additional ARO regulatory assets for EGUs no longer in operation, additional property, plant and equipment for EGUs still in operation, and a pre-tax non-cash charge of $20 million recorded to “Other operation and maintenance” in Alliant Energy’s and IPL’s income statements for the portion allocated to IPL’s steam business for IPL’s Prairie Creek Generating Station and the retired Sixth Street Generating Station as established in prior rate reviews. The amounts recorded in the second quarter of 2024 are expected to be adjusted in the future as additional information is obtained for the specific site closure plans, including the determination of whether or not individual sites are considered legal obligations and the acceptance and approval of compliance approaches, which could change management assumptions and result in a material change to the recorded amounts.

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- Definition The entire disclosure for an asset retirement obligation and the associated long-lived asset. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481850/410-20-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org//410-20/tableOfContent Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -SubTopic 20 -Topic 410 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481850/410-20-50-2 + Details
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