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Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022
Public Utilities, General Disclosures [Line Items] |  |  |  |
Depreciation, Nonproduction | $ (19.0) | $ (2.2) | $ (9.7) | $ (4.5)
Customer Refund Liability, Current | $ 12.4 |  | $ 12.4 |
Columbia Of Ohio |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Percentage |  |  | 21.30% |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  | $ 221.4 |

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