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Fair Value Measurements (Fair Value Of Net Derivative Assets (Liabilities)) (Details) - Commodity Contracts [Member] - USD ($) $ in Millions | Jun. 30, 2022 | Mar. 31, 2022 | Dec. 31, 2021 | Jun. 30, 2021 | Mar. 31, 2021 | Dec. 31, 2020
--- | --- | --- | --- | --- | --- | ---
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets | $ 72 | $ 10 | $ 29 | $ 39 | $ 15 | $ 29
Excluding Financial Transmission Rights [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative liabilities | (11) |  |  |  |  |
Fair value, net derivative assets |  |  | 9 |  |  |
Financial Transmission Rights [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets | 83 |  | 20 |  |  |
IPL [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets | 58 | 7 | 18 | 30 | 14 | 26
IPL [Member] | Excluding Financial Transmission Rights [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative liabilities | (8) |  |  |  |  |
Fair value, net derivative assets |  |  | 8 |  |  |
IPL [Member] | Financial Transmission Rights [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets | 66 |  | 10 |  |  |
WPL [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets | 14 | $ 3 | 11 | $ 9 | $ 1 | $ 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 | (3) |  |  |  |  |
Fair value, net derivative assets |  |  | 1 |  |  |
WPL [Member] | Financial Transmission Rights [Member] |  |  |  |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |
Fair value, net derivative assets | $ 17 |  | $ 10 |  |  |

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