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Fair Value Measurements (Fair Value Measurements) (Details) - USD ($) $ in Millions | Jun. 30, 2022 | Dec. 31, 2021
--- | --- | ---
Assets: |  |
Money market fund investments | $ 9 | $ 32
Deferred proceeds | 244 | 214
Liabilities: |  |
Long-term debt (incl. current maturities) | 7,403 | 8,330
IPL [Member] |  |
Assets: |  |
Money market fund investments | 9 | 32
Deferred proceeds | 244 | 214
Liabilities: |  |
Long-term debt (incl. current maturities) | 3,445 | 4,124
WPL [Member] |  |
Liabilities: |  |
Long-term debt (incl. current maturities) | 2,370 | 2,862
Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 359 | 176
Liabilities: |  |
Derivatives | 95 | 9
Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 207 | 84
Liabilities: |  |
Derivatives | 67 | 4
Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 152 | 92
Liabilities: |  |
Derivatives | 28 | 5
Level 1 [Member] |  |
Assets: |  |
Money market fund investments | 9 | 32
Deferred proceeds | 0 | 0
Liabilities: |  |
Long-term debt (incl. current maturities) | 0 | 0
Level 1 [Member] | IPL [Member] |  |
Assets: |  |
Money market fund investments | 9 | 32
Deferred proceeds | 0 | 0
Liabilities: |  |
Long-term debt (incl. current maturities) | 0 | 0
Level 1 [Member] | WPL [Member] |  |
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 2 [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 0 | 0
Liabilities: |  |
Long-term debt (incl. current maturities) | 7,402 | 8,329
Level 2 [Member] | IPL [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 0 | 0
Liabilities: |  |
Long-term debt (incl. current maturities) | 3,445 | 4,124
Level 2 [Member] | WPL [Member] |  |
Liabilities: |  |
Long-term debt (incl. current maturities) | 2,370 | 2,862
Level 2 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 272 | 146
Liabilities: |  |
Derivatives | 80 | 8
Level 2 [Member] | Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 138 | 65
Liabilities: |  |
Derivatives | 56 | 3
Level 2 [Member] | Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 134 | 81
Liabilities: |  |
Derivatives | 24 | 5
Level 3 [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 244 | 214
Liabilities: |  |
Long-term debt (incl. current maturities) | 1 | 1
Level 3 [Member] | IPL [Member] |  |
Assets: |  |
Money market fund investments | 0 | 0
Deferred proceeds | 244 | 214
Liabilities: |  |
Long-term debt (incl. current maturities) | 0 | 0
Level 3 [Member] | WPL [Member] |  |
Liabilities: |  |
Long-term debt (incl. current maturities) | 0 | 0
Level 3 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 87 | 30
Liabilities: |  |
Derivatives | 15 | 1
Level 3 [Member] | Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 69 | 19
Liabilities: |  |
Derivatives | 11 | 1
Level 3 [Member] | Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 18 | 11
Liabilities: |  |
Derivatives | 4 | 0
Carrying Amount [Member] |  |
Assets: |  |
Money market fund investments | 9 | 32
Deferred proceeds | 244 | 214
Liabilities: |  |
Long-term debt (incl. current maturities) | 7,714 | 7,368
Carrying Amount [Member] | IPL [Member] |  |
Assets: |  |
Money market fund investments | 9 | 32
Deferred proceeds | 244 | 214
Liabilities: |  |
Long-term debt (incl. current maturities) | 3,645 | 3,643
Carrying Amount [Member] | WPL [Member] |  |
Liabilities: |  |
Long-term debt (incl. current maturities) | 2,430 | 2,429
Carrying Amount [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 359 | 176
Liabilities: |  |
Derivatives | 95 | 9
Carrying Amount [Member] | Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 207 | 84
Liabilities: |  |
Derivatives | 67 | 4
Carrying Amount [Member] | Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 152 | 92
Liabilities: |  |
Derivatives | $ 28 | $ 5

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