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Benefit Plans (Expected Benefit Payments) (Details) $ in Millions | Dec. 31, 2024 USD ($)
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Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2025 | $ 95
Expected benefit payments, 2026 | 91
Expected benefit payments, 2027 | 89
Expected benefit payments, 2028 | 89
Expected benefit payments, 2029 | 88
Expected benefit payments, 2030 - 2034 | 391
Defined Benefit Pension Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2025 | 79
Expected benefit payments, 2026 | 75
Expected benefit payments, 2027 | 74
Expected benefit payments, 2028 | 74
Expected benefit payments, 2029 | 74
Expected benefit payments, 2030 - 2034 | 329
Other Postretirement Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2025 | 16
Expected benefit payments, 2026 | 16
Expected benefit payments, 2027 | 15
Expected benefit payments, 2028 | 15
Expected benefit payments, 2029 | 14
Expected benefit payments, 2030 - 2034 | 62
IPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2025 | 43
Expected benefit payments, 2026 | 40
Expected benefit payments, 2027 | 39
Expected benefit payments, 2028 | 39
Expected benefit payments, 2029 | 38
Expected benefit payments, 2030 - 2034 | 172
IPL [Member] | Defined Benefit Pension Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2025 | 36
Expected benefit payments, 2026 | 34
Expected benefit payments, 2027 | 33
Expected benefit payments, 2028 | 33
Expected benefit payments, 2029 | 32
Expected benefit payments, 2030 - 2034 | 148
IPL [Member] | Other Postretirement Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2025 | 7
Expected benefit payments, 2026 | 6
Expected benefit payments, 2027 | 6
Expected benefit payments, 2028 | 6
Expected benefit payments, 2029 | 6
Expected benefit payments, 2030 - 2034 | 24
WPL [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2025 | 40
Expected benefit payments, 2026 | 37
Expected benefit payments, 2027 | 37
Expected benefit payments, 2028 | 36
Expected benefit payments, 2029 | 36
Expected benefit payments, 2030 - 2034 | 167
WPL [Member] | Defined Benefit Pension Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2025 | 33
Expected benefit payments, 2026 | 31
Expected benefit payments, 2027 | 31
Expected benefit payments, 2028 | 31
Expected benefit payments, 2029 | 31
Expected benefit payments, 2030 - 2034 | 144
WPL [Member] | Other Postretirement Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected benefit payments, 2025 | 7
Expected benefit payments, 2026 | 6
Expected benefit payments, 2027 | 6
Expected benefit payments, 2028 | 5
Expected benefit payments, 2029 | 5
Expected benefit payments, 2030 - 2034 | $ 23

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