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v3.23.1

Fair Value Measurements (Fair Value Measurements) (Details) - USD ($) $ in Millions | Mar. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Assets: |  |
Money market fund investments | $ 148 | $ 10
Deferred proceeds | 153 | 185
Liabilities: |  |
Long-term debt (incl. current maturities) | 8,462 | 7,339
IPL [Member] |  |
Assets: |  |
Money market fund investments | 30 | 10
Deferred proceeds | 153 | 185
Liabilities: |  |
Long-term debt (incl. current maturities) | 3,335 | 3,228
WPL [Member] |  |
Assets: |  |
Money market fund investments | 83 | 0
Liabilities: |  |
Long-term debt (incl. current maturities) | 2,939 | 2,542
Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 122 | 237
Liabilities: |  |
Derivatives | 95 | 79
Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 69 | 138
Liabilities: |  |
Derivatives | 34 | 46
Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 53 | 99
Liabilities: |  |
Derivatives | 61 | 33
Interest Rate Swap [Member] |  |
Liabilities: |  |
Derivatives | 1 | 0
Level 1 [Member] |  |
Assets: |  |
Money market fund investments | 148 | 10
Deferred proceeds | 0 | 0
Liabilities: |  |
Long-term debt (incl. current maturities) | 0 | 0
Level 1 [Member] | IPL [Member] |  |
Assets: |  |
Money market fund investments | 30 | 10
Deferred proceeds | 0 | 0
Liabilities: |  |
Long-term debt (incl. current maturities) | 0 | 0
Level 1 [Member] | WPL [Member] |  |
Assets: |  |
Money market fund investments | 83 | 0
Liabilities: |  |
Long-term debt (incl. current maturities) | 0 | 0
Level 1 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 0 | 0
Liabilities: |  |
Derivatives | 0 | 0
Level 1 [Member] | Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 0 | 0
Liabilities: |  |
Derivatives | 0 | 0
Level 1 [Member] | Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 0 | 0
Liabilities: |  |
Derivatives | 0 | 0
Level 1 [Member] | Interest Rate Swap [Member] |  |
Liabilities: |  |
Derivatives | 0 | 0
Level 2 [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 0 | 0
Liabilities: |  |
Long-term debt (incl. current maturities) | 8,461 | 7,338
Level 2 [Member] | IPL [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 0 | 0
Liabilities: |  |
Long-term debt (incl. current maturities) | 3,335 | 3,228
Level 2 [Member] | WPL [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Liabilities: |  |
Long-term debt (incl. current maturities) | 2,939 | 2,542
Level 2 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 116 | 206
Liabilities: |  |
Derivatives | 84 | 67
Level 2 [Member] | Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 63 | 111
Liabilities: |  |
Derivatives | 28 | 35
Level 2 [Member] | Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 53 | 95
Liabilities: |  |
Derivatives | 56 | 32
Level 2 [Member] | Interest Rate Swap [Member] |  |
Liabilities: |  |
Derivatives | 1 | 0
Level 3 [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 153 | 185
Liabilities: |  |
Long-term debt (incl. current maturities) | 1 | 1
Level 3 [Member] | IPL [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 153 | 185
Liabilities: |  |
Long-term debt (incl. current maturities) | 0 | 0
Level 3 [Member] | WPL [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Liabilities: |  |
Long-term debt (incl. current maturities) | 0 | 0
Level 3 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 6 | 31
Liabilities: |  |
Derivatives | 11 | 12
Level 3 [Member] | Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 6 | 27
Liabilities: |  |
Derivatives | 6 | 11
Level 3 [Member] | Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 0 | 4
Liabilities: |  |
Derivatives | 5 | 1
Level 3 [Member] | Interest Rate Swap [Member] |  |
Liabilities: |  |
Derivatives | 0 | 0
Carrying Amount [Member] |  |
Assets: |  |
Money market fund investments | 148 | 10
Deferred proceeds | 153 | 185
Liabilities: |  |
Long-term debt (incl. current maturities) | 8,940 | 8,076
Carrying Amount [Member] | IPL [Member] |  |
Assets: |  |
Money market fund investments | 30 | 10
Deferred proceeds | 153 | 185
Liabilities: |  |
Long-term debt (incl. current maturities) | 3,647 | 3,646
Carrying Amount [Member] | WPL [Member] |  |
Assets: |  |
Money market fund investments | 83 | 0
Liabilities: |  |
Long-term debt (incl. current maturities) | 3,067 | 2,770
Carrying Amount [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 122 | 237
Liabilities: |  |
Derivatives | 95 | 79
Carrying Amount [Member] | Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 69 | 138
Liabilities: |  |
Derivatives | 34 | 46
Carrying Amount [Member] | Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 53 | 99
Liabilities: |  |
Derivatives | 61 | 33
Carrying Amount [Member] | Interest Rate Swap [Member] |  |
Liabilities: |  |
Derivatives | $ 1 | $ 0

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