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v3.23.3

Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022 | Dec. 31, 2022
Derivative Instruments [Line Items] |  |  |  |  |
Non-current interest rate swap liabilities | $ 544 |  | $ 544 |  | $ 518
Accumulated other comprehensive income, interest rate swap | 4 |  | 4 |  | $ 0
Interest expense, interest rate swap | 99 | $ 83 | 289 | $ 235 |
Alliant Energy Finance LLC [Member] | Interest Rate Swap [Member] | Term Loan Credit Agreement [Member] |  |  |  |  |
Derivative Instruments [Line Items] |  |  |  |  |
Interest rate swap | $ 300 |  | $ 300 |  |
Interest rate swap, fixed interest rate percentage | 3.93% |  | 3.93% |  |
Non-current interest rate swap liabilities | $ 6 |  | $ 6 |  |
Accumulated other comprehensive income, interest rate swap | 4 |  | 4 |  |
Interest expense, interest rate swap | $ 1 |  | $ 2 |  |

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