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Summary Of Significant Accounting Policies (Narrative) (Details) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2023 USD ($) customer MW | Dec. 31, 2022 USD ($)
Cash, Cash Equivalents and Restricted Cash: |  |
Money market fund investments | $ | $ 45 | $ 10
Money market fund investments interest rate, percentage | 5.00% |
Non-utility wind farm in Oklahoma [Member] |  |
General: |  |
Ownership interest | 50.00% |
IPL [Member] |  |
General: |  |
Generation and distribution of steam, number of customers served (in customers) | customer | 2 |
Cash, Cash Equivalents and Restricted Cash: |  |
Money market fund investments | $ | $ 45 | $ 10
Money market fund investments interest rate, percentage | 5.00% |
Property, Plant and Equipment: |  |
AFUDC accrual recorded, percentage of estimated CWIP | 100.00% |
WPL [Member] |  |
Property, Plant and Equipment: |  |
AFUDC accrual recorded, percentage of estimated CWIP | 50.00% |
AFUDC accrual recorded, percentage earning a return as part of rate base | 50.00% |
AFUDC rates, projects with approval | 100.00% |
Alliant Energy Finance, LLC [Member] |  |
General: |  |
Electric capacity of wind farm (in megawatts) | MW | 225 |
Alliant Energy Finance, LLC [Member] | Non-utility wind farm in Oklahoma [Member] |  |
General: |  |
Ownership interest | 50.00% |
Sheboygan Falls Energy Facility [Member] |  |
General: |  |
Fossil-fueled EGU capacity (in megawatts) | MW | 347 |

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