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v3.24.0.1

Fair Value Measurements (Recurring Fair Value Measurements) (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Carrying Amount [Member] |  |
Assets: |  |
Money market fund investments | $ 45 | $ 10
Deferred proceeds | 216 | 185
Liabilities and equity: |  |
Long-term debt (including current maturities) | 9,034 | 8,076
Carrying Amount [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 88 | 237
Liabilities and equity: |  |
Derivatives | 98 | 79
Carrying Amount [Member] | Interest Rate Swap |  |
Assets: |  |
Derivatives | 1 | 0
Money market fund investments | 45 | 10
Deferred proceeds | 216 | 185
Liabilities and equity: |  |
Long-Term Debt, Fair Value | 8,677 | 7,339
Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 88 | 237
Liabilities and equity: |  |
Derivatives | 98 | 79
Interest Rate Swap |  |
Assets: |  |
Derivatives | 1 | 0
Level 1 [Member] |  |
Assets: |  |
Money market fund investments | 45 | 10
Deferred proceeds | 0 | 0
Liabilities and equity: |  |
Long-Term Debt, Fair Value | 0 | 0
Level 1 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 0 | 0
Liabilities and equity: |  |
Derivatives | 0 | 0
Level 1 [Member] | Interest Rate Swap |  |
Assets: |  |
Derivatives | 0 | 0
Level 2 [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 0 | 0
Liabilities and equity: |  |
Long-Term Debt, Fair Value | 8,677 | 7,338
Level 2 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 59 | 206
Liabilities and equity: |  |
Derivatives | 93 | 67
Level 2 [Member] | Interest Rate Swap |  |
Assets: |  |
Derivatives | 1 | 0
Level 3 [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 216 | 185
Liabilities and equity: |  |
Long-Term Debt, Fair Value | 0 | 1
Level 3 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 29 | 31
Liabilities and equity: |  |
Derivatives | 5 | 12
Level 3 [Member] | Interest Rate Swap |  |
Assets: |  |
Derivatives | 0 | 0
IPL [Member] | Carrying Amount [Member] |  |
Assets: |  |
Money market fund investments | 45 | 10
Deferred proceeds | 216 | 185
Liabilities and equity: |  |
Long-term debt (including current maturities) | 3,945 | 3,646
IPL [Member] | Carrying Amount [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 54 | 138
Liabilities and equity: |  |
Derivatives | 30 | 46
IPL [Member] |  |
Assets: |  |
Money market fund investments | 45 | 10
Deferred proceeds | 216 | 185
Liabilities and equity: |  |
Long-Term Debt, Fair Value | 3,664 | 3,228
IPL [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 54 | 138
Liabilities and equity: |  |
Derivatives | 30 | 46
IPL [Member] | Level 1 [Member] |  |
Assets: |  |
Money market fund investments | 45 | 10
Deferred proceeds | 0 | 0
Liabilities and equity: |  |
Long-Term Debt, Fair Value | 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, Fair Value | 3,664 | 3,228
IPL [Member] | Level 2 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 30 | 111
Liabilities and equity: |  |
Derivatives | 25 | 35
IPL [Member] | Level 3 [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 216 | 185
Liabilities and equity: |  |
Long-Term Debt, Fair Value | 0 | 0
IPL [Member] | Level 3 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 24 | 27
Liabilities and equity: |  |
Derivatives | 5 | 11
WPL [Member] | Carrying Amount [Member] |  |
Liabilities and equity: |  |
Long-term debt (including current maturities) | 3,070 | 2,770
WPL [Member] | Carrying Amount [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 34 | 99
Liabilities and equity: |  |
Derivatives | 68 | 33
WPL [Member] |  |
Liabilities and equity: |  |
Long-Term Debt, Fair Value | 2,933 | 2,542
WPL [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 34 | 99
Liabilities and equity: |  |
Derivatives | 68 | 33
WPL [Member] | Level 1 [Member] |  |
Liabilities and equity: |  |
Long-Term Debt, Fair Value | 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, Fair Value | 2,933 | 2,542
WPL [Member] | Level 2 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 29 | 95
Liabilities and equity: |  |
Derivatives | 68 | 32
WPL [Member] | Level 3 [Member] |  |
Liabilities and equity: |  |
Long-Term Debt, Fair Value | 0 | 0
WPL [Member] | Level 3 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 5 | 4
Liabilities and equity: |  |
Derivatives | $ 0 | $ 1

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