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Benefit Plans (Expected Benefit Payments) (Details) $ in Millions | Dec. 31, 2023 USD ($)
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Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2024 | $ 90
Expected benefit payments, 2025 | 90
Expected benefit payments, 2026 | 90
Expected benefit payments, 2027 | 91
Expected benefit payments, 2028 | 90
Expected benefit payments, 2029 - 2033 | 408
Defined Benefit Pension Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2024 | 73
Expected benefit payments, 2025 | 73
Expected benefit payments, 2026 | 74
Expected benefit payments, 2027 | 75
Expected benefit payments, 2028 | 75
Expected benefit payments, 2029 - 2033 | 343
Other Postretirement Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2024 | 17
Expected benefit payments, 2025 | 17
Expected benefit payments, 2026 | 16
Expected benefit payments, 2027 | 16
Expected benefit payments, 2028 | 15
Expected benefit payments, 2029 - 2033 | 65
IPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2024 | 41
Expected benefit payments, 2025 | 41
Expected benefit payments, 2026 | 41
Expected benefit payments, 2027 | 39
Expected benefit payments, 2028 | 39
Expected benefit payments, 2029 - 2033 | 176
IPL [Member] | Defined Benefit Pension Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2024 | 34
Expected benefit payments, 2025 | 34
Expected benefit payments, 2026 | 34
Expected benefit payments, 2027 | 33
Expected benefit payments, 2028 | 33
Expected benefit payments, 2029 - 2033 | 151
IPL [Member] | Other Postretirement Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2024 | 7
Expected benefit payments, 2025 | 7
Expected benefit payments, 2026 | 7
Expected benefit payments, 2027 | 6
Expected benefit payments, 2028 | 6
Expected benefit payments, 2029 - 2033 | 25
WPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2024 | 39
Expected benefit payments, 2025 | 39
Expected benefit payments, 2026 | 37
Expected benefit payments, 2027 | 37
Expected benefit payments, 2028 | 37
Expected benefit payments, 2029 - 2033 | 170
WPL [Member] | Defined Benefit Pension Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2024 | 32
Expected benefit payments, 2025 | 32
Expected benefit payments, 2026 | 31
Expected benefit payments, 2027 | 31
Expected benefit payments, 2028 | 31
Expected benefit payments, 2029 - 2033 | 146
WPL [Member] | Other Postretirement Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2024 | 7
Expected benefit payments, 2025 | 7
Expected benefit payments, 2026 | 6
Expected benefit payments, 2027 | 6
Expected benefit payments, 2028 | 6
Expected benefit payments, 2029 - 2033 | $ 24

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