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RATE MATTERS - APCo and WPCo Rate Matters (Details) - APCo $ in Millions | 1 Months Ended |  |
--- | --- | --- | ---
Apr. 30, 2025 USD ($) | Mar. 31, 2025 USD ($) | Nov. 30, 2024 USD ($) consecutiveYear | Aug. 31, 2024 USD ($) | Apr. 30, 2024 USD ($) | Mar. 31, 2024 USD ($) | Jan. 31, 2024 USD ($) | Jan. 31, 2025 USD ($) | Feb. 29, 2024 USD ($)
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | $ 2,395.8 |  |  |  |  |  |  |
ENEC Under-Recovery Regulatory Assets (as of February 28, 2023) |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 321.1 |  |  |  |  |  |  |
Undepreciated Utility Plant Balances of Amos, Mitchell and Mountaineer (as of December 31, 2022) |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 1,704.2 |  |  |  |  |  |  |
Forecasted Undepreciated CCR and ELG Investments of Amos, Mitchell and Mountaineer (as of November 30, 2024) |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 236.8 |  |  |  |  |  |  |
Storm-Related Costs |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 117.9 |  |  |  |  |  |  |
Upfront Financing Costs |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 15.8 |  |  |  |  |  |  |
West Virginia |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 2,400.0 |  |  |  |  |  |  |
West Virginia | ENEC Under-Recovery Regulatory Assets (as of February 28, 2023) |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 321.0 |  |  |  |  |  |  |
West Virginia | Forecasted Undepreciated CCR and ELG Investments of Amos, Mitchell and Mountaineer (as of November 30, 2024) |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 237.0 |  |  |  |  |  |  |
West Virginia | Storm-Related Costs |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 118.0 |  |  |  |  |  |  |
APCo Portion |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 1,532.5 |  |  |  |  |  |  |
APCo Portion | ENEC Under-Recovery Regulatory Assets (as of February 28, 2023) |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 174.3 |  |  |  |  |  |  |
APCo Portion | Undepreciated Utility Plant Balances of Amos, Mitchell and Mountaineer (as of December 31, 2022) |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 1,145.5 |  |  |  |  |  |  |
APCo Portion | Forecasted Undepreciated CCR and ELG Investments of Amos, Mitchell and Mountaineer (as of November 30, 2024) |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 87.6 |  |  |  |  |  |  |
APCo Portion | Storm-Related Costs |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 115.0 |  |  |  |  |  |  |
APCo Portion | Upfront Financing Costs |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 10.1 |  |  |  |  |  |  |
Mitchell & Mountaineer Plants | West Virginia | Undepreciated Utility Plant Balances of Amos, Mitchell and Mountaineer (as of December 31, 2022) |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 1,700.0 |  |  |  |  |  |  |
WPCo Portion |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 863.3 |  |  |  |  |  |  |
WPCo Portion | ENEC Under-Recovery Regulatory Assets (as of February 28, 2023) |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 146.8 |  |  |  |  |  |  |
WPCo Portion | Undepreciated Utility Plant Balances of Amos, Mitchell and Mountaineer (as of December 31, 2022) |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 558.7 |  |  |  |  |  |  |
WPCo Portion | Forecasted Undepreciated CCR and ELG Investments of Amos, Mitchell and Mountaineer (as of November 30, 2024) |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 149.2 |  |  |  |  |  |  |
WPCo Portion | Storm-Related Costs |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 2.9 |  |  |  |  |  |  |
WPCo Portion | Upfront Financing Costs |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Regulatory asset, requested to be financed through securitization |  | 5.7 |  |  |  |  |  |  |
ENEC Filing |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Under recovered costs disallowance |  | 232.0 |  |  |  |  | $ 232.0 |  | $ 232.0
Approved recovery under recovered costs |  |  |  |  | $ 321.0 |  |  |  |
Approved carrying charges |  |  |  |  | 4.00% |  | 4.00% |  |
Approved carrying charges, recovery period |  |  |  |  | 10 years |  | 10 years |  |
Requested annual base rate increase |  |  |  |  | $ 58.0 |  |  |  |
ENEC Filing | Period ending February 29, 2024 |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Requested annual base rate increase |  |  |  |  | 20.0 |  |  |  |
Approved annual base rate increase |  | $ 20.0 |  |  |  |  |  |  |
ENEC Filing | Period September 2024 through August 2025 |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Requested annual base rate increase |  |  |  |  | $ 38.0 |  |  |  |
Approved annual base rate increase |  |  |  | $ 38.0 |  |  |  |  |
ENEC Filing | APCo Portion |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Under recovered costs disallowance |  |  |  |  |  |  | $ 136.0 |  |
Approved recovery under recovered costs |  |  |  |  |  |  | $ 174.0 |  |
Virginia Fuel Adjustment Clause |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Under recovered costs disallowance |  |  |  |  |  |  |  | $ 20.0 |
Virginia Fuel Adjustment Clause | Subsequent Event |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Under recovered costs disallowance | $ 20.0 |  |  |  |  |  |  |  |
2024 West Virginia Base Rate Case |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Approved recovery under recovered costs |  |  | $ 118.0 |  |  |  |  |  |
Requested annual base rate increase |  |  | $ 251.0 |  |  |  |  |  |
Requested return on equity |  |  | 10.80% |  |  |  |  |  |
Requested debt capital structure |  |  | 52.00% |  |  |  |  |  |
Requested equity capital structure |  |  | 48.00% |  |  |  |  |  |
Regulatory assets expected to be recovered through securitization |  |  | $ 2,400.0 |  |  |  |  |  |
Requested annual increase without securitization |  |  | $ 37.0 |  |  |  |  |  |
Annual increase april 1st surcharge |  |  | 3.00% |  |  |  |  |  |
Annual increase, surcharges, number of consecutive years | consecutiveYear |  |  | 4 |  |  |  |  |  |
Annual increase april 1st surcharge, proposed filing period |  |  | 4 years |  |  |  |  |  |
Requested recovery, under-recovered costs, period |  |  | 3 years |  |  |  |  |  |
2024 West Virginia Base Rate Case | Subsequent Event |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Average rate base | 13 months |  |  |  |  |  |  |  |
Requested recovery, under-recovered costs | $ 118.0 |  |  |  |  |  |  |  |
Requested recovery, under-recovered costs, period | 5 years |  |  |  |  |  |  |  |
2024 West Virginia Base Rate Case | Subsequent Event | Minimum |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Requested annual base rate increase | $ 49.0 |  |  |  |  |  |  |  |
Requested return on equity | 9.10% |  |  |  |  |  |  |  |
2024 West Virginia Base Rate Case | Subsequent Event | Maximum |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Requested annual base rate increase | $ 91.0 |  |  |  |  |  |  |  |
Requested return on equity | 9.25% |  |  |  |  |  |  |  |
Modified Rate Base Cost |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Requested annual base rate increase |  |  | $ 94.0 |  |  |  |  |  |
Mitchell Base Rate Surcharge |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Requested annual base rate increase |  |  | $ 21.0 |  |  |  |  |  |
West Virginia Modified Rate Base Cost |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |
Requested annual base rate increase |  |  |  |  |  | $ 32.0 |  |  |

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