Summary Of Significant Accounting Policies (Policy)	6 Months Ended
Jun. 30, 2022
General, Basis of Accounting	The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2021 Form 10-K.In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the six months ended June 30, 2022 are not necessarily indicative of results that may be expected for the year ending December 31, 2022.
General, Use of Estimates	A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred.
General, Reclassification	Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.
Variable Interest Entities	A portion of WPL’s solar generation projects is financed, and is expected to be financed, with capital from tax equity partners through joint ventures. In 2022, WPL 2022 Solar Holdco, LLC was formed as a joint venture to own and operate project companies responsible for the construction, ownership and operation of various solar generation assets. Members of the joint venture are a WPL subsidiary (the managing member) and a tax equity partner. In June 2022, the WPL subsidiary and the tax equity partner contributed $62 million and $29 million, respectively, to WPL 2022 Solar Holdco, LLC in exchange for membership interests. In June 2022, $88 million of the contributed funds were paid to WPL in exchange for equity interests in the project companies. Once asset construction is complete, the WPL subsidiary and the tax equity partner will make additional cash contributions based on the fair value of the solar generation assets. Earnings, tax attributes, and cash flows from the joint venture will be allocated to both the WPL subsidiary and the tax equity partner in varying percentages over the life of the partnership. Once the tax equity partner has earned its negotiated rate of return and the agreed upon contractual date has been reached, WPL has the option to purchase the remaining interest in the joint venture from the tax equity partner at fair value. Alliant Energy and WPL consolidate this joint venture as it is a VIE in which WPL holds a variable interest, and WPL controls decisions that are significant to the joint venture’s ongoing operations and economic results (i.e., WPL is the primary beneficiary). The joint venture is subject to profit sharing arrangements in which the allocation of the joint venture’s cash distributions and tax benefits to members is based on factors other than members' relative ownership percentages. As a result, WPL utilizes the Hypothetical Liquidation at Book Value (HLBV) method to allocate proceeds to each partner at the balance sheet date based on the liquidation provisions of the related joint venture's operating agreement and to adjust the amount of the VIE's net income attributable to Alliant Energy and WPL, as well as the noncontrolling interest during the period. In each reporting period, the application of HLBV to WPL’s consolidated VIE results in a difference between the amount of profit from the consolidated joint venture and the amount included in WPL’s regulated rates. WPL is subject to GAAP provisions for regulated operations and recognizes a regulatory liability or regulatory asset for amounts representing the timing difference between WPL’s profit earned from the joint venture and the amount included in regulated rates for recovery of its solar generation projects. The amounts recorded in income will ultimately reflect the amount allowed in regulated rates to recover WPL’s investments over the useful life of the solar projects. Refer to Note 6 for discussion of a noncontrolling interest associated with the joint venture.
IPL [Member]
General, Basis of Accounting	The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2021 Form 10-K.In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the six months ended June 30, 2022 are not necessarily indicative of results that may be expected for the year ending December 31, 2022.
General, Use of Estimates	A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred.
General, Reclassification	Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.
WPL [Member]
General, Basis of Accounting	The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2021 Form 10-K.In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the six months ended June 30, 2022 are not necessarily indicative of results that may be expected for the year ending December 31, 2022.
General, Use of Estimates	A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred.
General, Reclassification	Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.
Variable Interest Entities	A portion of WPL’s solar generation projects is financed, and is expected to be financed, with capital from tax equity partners through joint ventures. In 2022, WPL 2022 Solar Holdco, LLC was formed as a joint venture to own and operate project companies responsible for the construction, ownership and operation of various solar generation assets. Members of the joint venture are a WPL subsidiary (the managing member) and a tax equity partner. In June 2022, the WPL subsidiary and the tax equity partner contributed $62 million and $29 million, respectively, to WPL 2022 Solar Holdco, LLC in exchange for membership interests. In June 2022, $88 million of the contributed funds were paid to WPL in exchange for equity interests in the project companies. Once asset construction is complete, the WPL subsidiary and the tax equity partner will make additional cash contributions based on the fair value of the solar generation assets. Earnings, tax attributes, and cash flows from the joint venture will be allocated to both the WPL subsidiary and the tax equity partner in varying percentages over the life of the partnership. Once the tax equity partner has earned its negotiated rate of return and the agreed upon contractual date has been reached, WPL has the option to purchase the remaining interest in the joint venture from the tax equity partner at fair value. Alliant Energy and WPL consolidate this joint venture as it is a VIE in which WPL holds a variable interest, and WPL controls decisions that are significant to the joint venture’s ongoing operations and economic results (i.e., WPL is the primary beneficiary). The joint venture is subject to profit sharing arrangements in which the allocation of the joint venture’s cash distributions and tax benefits to members is based on factors other than members' relative ownership percentages. As a result, WPL utilizes the Hypothetical Liquidation at Book Value (HLBV) method to allocate proceeds to each partner at the balance sheet date based on the liquidation provisions of the related joint venture's operating agreement and to adjust the amount of the VIE's net income attributable to Alliant Energy and WPL, as well as the noncontrolling interest during the period. In each reporting period, the application of HLBV to WPL’s consolidated VIE results in a difference between the amount of profit from the consolidated joint venture and the amount included in WPL’s regulated rates. WPL is subject to GAAP provisions for regulated operations and recognizes a regulatory liability or regulatory asset for amounts representing the timing difference between WPL’s profit earned from the joint venture and the amount included in regulated rates for recovery of its solar generation projects. The amounts recorded in income will ultimately reflect the amount allowed in regulated rates to recover WPL’s investments over the useful life of the solar projects. Refer to Note 6 for discussion of a noncontrolling interest associated with the joint venture.

Summary Of Significant Accounting Policies (Policy)

6 Months Ended

Jun. 30, 2022

The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2021 Form 10-K.In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the six months ended June 30, 2022 are not necessarily indicative of results that may be expected for the year ending December 31, 2022.

General, Use of Estimates

A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred.

General, Reclassification

Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.

Variable Interest Entities

A portion of WPL’s solar generation projects is financed, and is expected to be financed, with capital from tax equity partners through joint ventures.

In 2022, WPL 2022 Solar Holdco, LLC was formed as a joint venture to own and operate project companies responsible for the construction, ownership and operation of various solar generation assets. Members of the joint venture are a WPL subsidiary (the managing member) and a tax equity partner. In June 2022, the WPL subsidiary and the tax equity partner contributed $62 million and $29 million, respectively, to WPL 2022 Solar Holdco, LLC in exchange for membership interests. In June 2022, $88 million of the contributed funds were paid to WPL in exchange for equity interests in the project companies. Once asset construction is complete, the WPL subsidiary and the tax equity partner will make additional cash contributions based on the fair value of the solar generation assets. Earnings, tax attributes, and cash flows from the joint venture will be allocated to both the WPL subsidiary and the tax equity partner in varying percentages over the life of the partnership. Once the tax equity partner has earned its negotiated rate of return and the agreed upon contractual date has been reached, WPL has the option to purchase the remaining interest in the joint venture from the tax equity partner at fair value.

Alliant Energy and WPL consolidate this joint venture as it is a VIE in which WPL holds a variable interest, and WPL controls decisions that are significant to the joint venture’s ongoing operations and economic results (i.e., WPL is the primary beneficiary).

The joint venture is subject to profit sharing arrangements in which the allocation of the joint venture’s cash distributions and tax benefits to members is based on factors other than members' relative ownership percentages. As a result, WPL utilizes the Hypothetical Liquidation at Book Value (HLBV) method to allocate proceeds to each partner at the balance sheet date based on the liquidation provisions of the related joint venture's operating agreement and to adjust the amount of the VIE's net income attributable to Alliant Energy and WPL, as well as the noncontrolling interest during the period.

In each reporting period, the application of HLBV to WPL’s consolidated VIE results in a difference between the amount of profit from the consolidated joint venture and the amount included in WPL’s regulated rates. WPL is subject to GAAP provisions for regulated operations and recognizes a regulatory liability or regulatory asset for amounts representing the timing difference between WPL’s profit earned from the joint venture and the amount included in regulated rates for recovery of its solar generation projects. The amounts recorded in income will ultimately reflect the amount allowed in regulated rates to recover WPL’s investments over the useful life of the solar projects.

Refer to Note 6 for discussion of a noncontrolling interest associated with the joint venture.

IPL [Member]

General, Basis of Accounting

General, Use of Estimates

A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred.

General, Reclassification

Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.

WPL [Member]

General, Basis of Accounting

General, Use of Estimates

A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred.

General, Reclassification

Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.

Variable Interest Entities

A portion of WPL’s solar generation projects is financed, and is expected to be financed, with capital from tax equity partners through joint ventures.

Refer to Note 6 for discussion of a noncontrolling interest associated with the joint venture.