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Fair Value Measurements (Recurring Fair Value Measurements) (Details) - USD ($) $ in Millions | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Assets: |  |
Money market fund investments | $ 10 | $ 32
Deferred proceeds | 185 | 214
Liabilities and equity: |  |
Long-term debt (including current maturities) | 7,339 | 8,330
Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 237 | 176
Liabilities and equity: |  |
Derivatives | 79 | 9
Level 1 [Member] |  |
Assets: |  |
Money market fund investments | 10 | 32
Deferred proceeds | 0 | 0
Liabilities and equity: |  |
Long-term debt (including current maturities) | 0 | 0
Level 1 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 0 | 0
Liabilities and equity: |  |
Derivatives | 0 | 0
Level 2 [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 0 | 0
Liabilities and equity: |  |
Long-term debt (including current maturities) | 7,338 | 8,329
Level 2 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 206 | 146
Liabilities and equity: |  |
Derivatives | 67 | 8
Level 3 [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 185 | 214
Liabilities and equity: |  |
Long-term debt (including current maturities) | 1 | 1
Level 3 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 31 | 30
Liabilities and equity: |  |
Derivatives | 12 | 1
Carrying Amount [Member] |  |
Assets: |  |
Money market fund investments | 10 | 32
Deferred proceeds | 185 | 214
Liabilities and equity: |  |
Long-term debt (including current maturities) | 8,076 | 7,368
Carrying Amount [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 237 | 176
Liabilities and equity: |  |
Derivatives | 79 | 9
IPL [Member] |  |
Assets: |  |
Money market fund investments | 10 | 32
Deferred proceeds | 185 | 214
Liabilities and equity: |  |
Long-term debt (including current maturities) | 3,228 | 4,124
IPL [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 138 | 84
Liabilities and equity: |  |
Derivatives | 46 | 4
IPL [Member] | Level 1 [Member] |  |
Assets: |  |
Money market fund investments | 10 | 32
Deferred proceeds | 0 | 0
Liabilities and equity: |  |
Long-term debt (including current maturities) | 0 | 0
IPL [Member] | Level 1 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 0 | 0
Liabilities and equity: |  |
Derivatives | 0 | 0
IPL [Member] | Level 2 [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 0 | 0
Liabilities and equity: |  |
Long-term debt (including current maturities) | 3,228 | 4,124
IPL [Member] | Level 2 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 111 | 65
Liabilities and equity: |  |
Derivatives | 35 | 3
IPL [Member] | Level 3 [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 185 | 214
Liabilities and equity: |  |
Long-term debt (including current maturities) | 0 | 0
IPL [Member] | Level 3 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 27 | 19
Liabilities and equity: |  |
Derivatives | 11 | 1
IPL [Member] | Carrying Amount [Member] |  |
Assets: |  |
Money market fund investments | 10 | 32
Deferred proceeds | 185 | 214
Liabilities and equity: |  |
Long-term debt (including current maturities) | 3,646 | 3,643
IPL [Member] | Carrying Amount [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 138 | 84
Liabilities and equity: |  |
Derivatives | 46 | 4
WPL [Member] |  |
Liabilities and equity: |  |
Long-term debt (including current maturities) | 2,542 | 2,862
WPL [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 99 | 92
Liabilities and equity: |  |
Derivatives | 33 | 5
WPL [Member] | Level 1 [Member] |  |
Liabilities and equity: |  |
Long-term debt (including current maturities) | 0 | 0
WPL [Member] | Level 1 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 0 | 0
Liabilities and equity: |  |
Derivatives | 0 | 0
WPL [Member] | Level 2 [Member] |  |
Liabilities and equity: |  |
Long-term debt (including current maturities) | 2,542 | 2,862
WPL [Member] | Level 2 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 95 | 81
Liabilities and equity: |  |
Derivatives | 32 | 5
WPL [Member] | Level 3 [Member] |  |
Liabilities and equity: |  |
Long-term debt (including current maturities) | 0 | 0
WPL [Member] | Level 3 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 4 | 11
Liabilities and equity: |  |
Derivatives | 1 | 0
WPL [Member] | Carrying Amount [Member] |  |
Liabilities and equity: |  |
Long-term debt (including current maturities) | 2,770 | 2,429
WPL [Member] | Carrying Amount [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 99 | 92
Liabilities and equity: |  |
Derivatives | $ 33 | $ 5

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