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Benefit Plans (Expected Benefit Payments) (Details) $ in Millions | Dec. 31, 2021 USD ($)
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Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2022 | $ 103
Expected benefit payments, 2023 | 100
Expected benefit payments, 2024 | 99
Expected benefit payments, 2025 | 99
Expected benefit payments, 2026 | 99
Expected benefit payments, 2027 - 2031 | 458
Defined Benefit Pension Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2022 | 85
Expected benefit payments, 2023 | 83
Expected benefit payments, 2024 | 82
Expected benefit payments, 2025 | 82
Expected benefit payments, 2026 | 83
Expected benefit payments, 2027 - 2031 | 387
Other Postretirement Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2022 | 18
Expected benefit payments, 2023 | 17
Expected benefit payments, 2024 | 17
Expected benefit payments, 2025 | 17
Expected benefit payments, 2026 | 16
Expected benefit payments, 2027 - 2031 | 71
IPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2022 | 48
Expected benefit payments, 2023 | 47
Expected benefit payments, 2024 | 46
Expected benefit payments, 2025 | 46
Expected benefit payments, 2026 | 45
Expected benefit payments, 2027 - 2031 | 202
IPL [Member] | Defined Benefit Pension Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2022 | 41
Expected benefit payments, 2023 | 40
Expected benefit payments, 2024 | 39
Expected benefit payments, 2025 | 39
Expected benefit payments, 2026 | 38
Expected benefit payments, 2027 - 2031 | 174
IPL [Member] | Other Postretirement Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2022 | 7
Expected benefit payments, 2023 | 7
Expected benefit payments, 2024 | 7
Expected benefit payments, 2025 | 7
Expected benefit payments, 2026 | 7
Expected benefit payments, 2027 - 2031 | 28
WPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2022 | 44
Expected benefit payments, 2023 | 43
Expected benefit payments, 2024 | 42
Expected benefit payments, 2025 | 42
Expected benefit payments, 2026 | 40
Expected benefit payments, 2027 - 2031 | 190
WPL [Member] | Defined Benefit Pension Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2022 | 37
Expected benefit payments, 2023 | 36
Expected benefit payments, 2024 | 35
Expected benefit payments, 2025 | 35
Expected benefit payments, 2026 | 34
Expected benefit payments, 2027 - 2031 | 163
WPL [Member] | Other Postretirement Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2022 | 7
Expected benefit payments, 2023 | 7
Expected benefit payments, 2024 | 7
Expected benefit payments, 2025 | 7
Expected benefit payments, 2026 | 6
Expected benefit payments, 2027 - 2031 | $ 27

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