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REGULATORY ENVIRONMENT - PGL QIP RIDER (Details) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2025 USD ($) Assurance | Sep. 30, 2024 USD ($) | Sep. 30, 2025 USD ($) Assurance | Sep. 30, 2024 USD ($) | Aug. 31, 2024 USD ($)
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Pre-tax charge to income | $ (304.6) | $ (270.2) | $ (1,353.3) | $ (1,232.1) |
Reduction in revenues | (2,104.0) | (1,863.5) | (7,263.0) | (6,315.7) |
Operation and maintenance expense | 605.1 | 566.8 | 1,809.3 | 1,631.0 |
Interest expense | 223.6 | 204.2 | 667.4 | $ 596.8 |
Illinois Commerce Commission (ICC) | PGL | 2016 Annual QIP Rider Reconciliation |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Disallowed capital costs |  |  |  |  | $ 14.8
Pre-tax charge to income |  | 25.3 |  |  |
Reduction in revenues |  | 12.9 |  |  |
Operation and maintenance expense |  | 12.1 |  |  |
Interest expense |  | $ 0.3 |  |  |
Illinois Commerce Commission (ICC) | PGL | QIP Rider Open Reconciliations 2017-2023 |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Aggregate capital costs during open reconciliation years | $ 2,900.0 |  | $ 2,900.0 |  |
Amount of assurance that QIP rider costs will be recoverable | Assurance | 0 |  | 0 |  |

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