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v3.20.2

Fair Value Measurements (Fair Value Measurements) (Details) - USD ($) $ in Millions | Jun. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Assets: |  |
Money market fund investments | $ 198.3 | $ 5.4
Deferred proceeds | 194.1 | 187.7
Liabilities: |  |
Long-term debt (incl. current maturities) | 7,769.8 | 6,919.9
IPL [Member] |  |
Assets: |  |
Money market fund investments | 198.3 | 5.4
Deferred proceeds | 194.1 | 187.7
Liabilities: |  |
Long-term debt (incl. current maturities) | 3,924.7 | 3,489.1
WPL [Member] |  |
Liabilities: |  |
Long-term debt (incl. current maturities) | 2,657.2 | 2,268.2
Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 42.4 | 26.8
Liabilities: |  |
Derivatives | 46.2 | 37.6
Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 37.0 | 22.3
Liabilities: |  |
Derivatives | 20.3 | 17.4
Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 5.4 | 4.5
Liabilities: |  |
Derivatives | 25.9 | 20.2
Level 1 [Member] |  |
Assets: |  |
Money market fund investments | 198.3 | 5.4
Deferred proceeds | 0.0 | 0.0
Liabilities: |  |
Long-term debt (incl. current maturities) | 0.0 | 0.0
Level 1 [Member] | IPL [Member] |  |
Assets: |  |
Money market fund investments | 198.3 | 5.4
Deferred proceeds | 0.0 | 0.0
Liabilities: |  |
Long-term debt (incl. current maturities) | 0.0 | 0.0
Level 1 [Member] | WPL [Member] |  |
Liabilities: |  |
Long-term debt (incl. current maturities) | 0.0 | 0.0
Level 1 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 0.0 | 0.0
Liabilities: |  |
Derivatives | 0.0 | 0.0
Level 1 [Member] | Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 0.0 | 0.0
Liabilities: |  |
Derivatives | 0.0 | 0.0
Level 1 [Member] | Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 0.0 | 0.0
Liabilities: |  |
Derivatives | 0.0 | 0.0
Level 2 [Member] |  |
Assets: |  |
Money market fund investments | 0.0 | 0.0
Deferred proceeds | 0.0 | 0.0
Liabilities: |  |
Long-term debt (incl. current maturities) | 7,768.1 | 6,917.9
Level 2 [Member] | IPL [Member] |  |
Assets: |  |
Money market fund investments | 0.0 | 0.0
Deferred proceeds | 0.0 | 0.0
Liabilities: |  |
Long-term debt (incl. current maturities) | 3,924.7 | 3,489.1
Level 2 [Member] | WPL [Member] |  |
Liabilities: |  |
Long-term debt (incl. current maturities) | 2,657.2 | 2,268.2
Level 2 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 4.6 | 4.8
Liabilities: |  |
Derivatives | 44.8 | 36.8
Level 2 [Member] | Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 3.3 | 2.8
Liabilities: |  |
Derivatives | 19.0 | 16.6
Level 2 [Member] | Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 1.3 | 2.0
Liabilities: |  |
Derivatives | 25.8 | 20.2
Level 3 [Member] |  |
Assets: |  |
Money market fund investments | 0.0 | 0.0
Deferred proceeds | 194.1 | 187.7
Liabilities: |  |
Long-term debt (incl. current maturities) | 1.7 | 2.0
Level 3 [Member] | IPL [Member] |  |
Assets: |  |
Money market fund investments | 0.0 | 0.0
Deferred proceeds | 194.1 | 187.7
Liabilities: |  |
Long-term debt (incl. current maturities) | 0.0 | 0.0
Level 3 [Member] | WPL [Member] |  |
Liabilities: |  |
Long-term debt (incl. current maturities) | 0.0 | 0.0
Level 3 [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 37.8 | 22.0
Liabilities: |  |
Derivatives | 1.4 | 0.8
Level 3 [Member] | Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 33.7 | 19.5
Liabilities: |  |
Derivatives | 1.3 | 0.8
Level 3 [Member] | Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 4.1 | 2.5
Liabilities: |  |
Derivatives | 0.1 | 0.0
Carrying Amount [Member] |  |
Assets: |  |
Money market fund investments | 198.3 | 5.4
Deferred proceeds | 194.1 | 187.7
Liabilities: |  |
Long-term debt (incl. current maturities) | 6,579.8 | 6,190.2
Carrying Amount [Member] | IPL [Member] |  |
Assets: |  |
Money market fund investments | 198.3 | 5.4
Deferred proceeds | 194.1 | 187.7
Liabilities: |  |
Long-term debt (incl. current maturities) | 3,343.5 | 3,147.3
Carrying Amount [Member] | WPL [Member] |  |
Liabilities: |  |
Long-term debt (incl. current maturities) | 2,129.4 | 1,932.7
Carrying Amount [Member] | Commodity Contracts [Member] |  |
Assets: |  |
Derivatives | 42.4 | 26.8
Liabilities: |  |
Derivatives | 46.2 | 37.6
Carrying Amount [Member] | Commodity Contracts [Member] | IPL [Member] |  |
Assets: |  |
Derivatives | 37.0 | 22.3
Liabilities: |  |
Derivatives | 20.3 | 17.4
Carrying Amount [Member] | Commodity Contracts [Member] | WPL [Member] |  |
Assets: |  |
Derivatives | 5.4 | 4.5
Liabilities: |  |
Derivatives | $ 25.9 | $ 20.2

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