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Fair Value Measurements (Fair Value Of Net Derivative Assets (Liabilities)) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions | Sep. 30, 2024 | Jun. 30, 2024 | Dec. 31, 2023 | Sep. 30, 2023 | Jun. 30, 2023 | Dec. 31, 2022
--- | --- | --- | --- | --- | --- | ---
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets | $ 37 | $ 51 | $ 24 | $ 43 | $ 54 | $ 19
Excluding Financial Transmission Rights [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets |  |  | 3 |  |  |
Fair value, net derivative liabilities | 0 |  |  |  |  |
Financial Transmission Rights [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets | 37 |  | 21 |  |  |
IPL [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets | 29 | 40 | 19 | 35 | 41 | 16
IPL [Member] | Excluding Financial Transmission Rights [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets |  |  | 3 |  |  |
Fair value, net derivative liabilities | 0 |  |  |  |  |
IPL [Member] | Financial Transmission Rights [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets | 29 |  | 16 |  |  |
WPL [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets | 8 | $ 11 | 5 | $ 8 | $ 13 | $ 3
WPL [Member] | Excluding Financial Transmission Rights [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative liabilities | 0 |  | 0 |  |  |
WPL [Member] | Financial Transmission Rights [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets | $ 8 |  | $ 5 |  |  |

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