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Regulatory Matters (Narrative) (Details) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2024 USD ($) MW | Jun. 30, 2023 USD ($) | Jun. 30, 2024 USD ($) MW | Jun. 30, 2023 USD ($)
Public Utilities, General Disclosures [Line Items] |  |  |  |
Depreciation, Nonproduction | $ | $ 13.1 | $ 13.7 | $ 16.6 | $ 9.3
Rosewater |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Nameplate Capacity | 102 |  | 102 |
NIPSCO |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Nameplate Capacity | 400 |  | 400 |

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