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REGULATORY MATTERS - APC Rate NDR and Reliability Reserve Accounting Order (Details) - USD ($) | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Jul. 12, 2022
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |
Reclassified amount | $ (97,017,000,000) | $ (90,703,000,000) | $ (97,017,000,000) | $ (90,703,000,000) |  |
Other regulatory assets | 804,000,000 | 1,120,000,000 | 804,000,000 | 1,120,000,000 |  |
Reliability reserve, amount deferred | 84,000,000 | 63,000,000 | 84,000,000 | 63,000,000 | $ 191,000,000 |
Revision of Prior Period, Reclassification, Adjustment |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |
Reclassified amount |  |  |  |  | 600,000,000 |
Other utility plant, net |  |  |  |  | 600,000,000 |
Alabama Power |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |
Minimum natural disaster reserve balance, triggering establishment charge | 50,000,000 |  | 50,000,000 |  |  |
Natural disaster reserve authorized limit | 75,000,000 |  | 75,000,000 |  | 35,000,000 |
Maximum rate NDR charge per month, monthly residential customer account | 2.50 |  | 2.50 |  |  | $ 5.00
Maximum rate NDR charge per month, monthly nonresidential customer account | 5.00 |  | 5.00 |  |  | $ 10.00
Annual recovery amount |  |  | 12,000,000 | 12,000,000 | 14,000,000 |
NDR, expected recovery amount |  |  | 12,000,000 |  |  |
Regulatory asset, amortization period | 70,000,000 | 76,000,000 | 70,000,000 | 76,000,000 |  |
Reclassified amount | (24,760,000,000) | (24,298,000,000) | (24,760,000,000) | (24,298,000,000) |  |
Other regulatory assets | 332,000,000 | 385,000,000 | 332,000,000 | 385,000,000 |  |
Reliability reserve, amount deferred | 63,000,000 | 52,000,000 | $ 63,000,000 | $ 52,000,000 | $ 166,000,000 |
Alabama Power | Reliability reserves |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |
Accrual | $ 12,000,000 | $ 23,000,000 |  |  |  |
Alabama Power | Maximum |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |
Maximum period for recovery deferred stock related operations and maintenance costs and any future reserve deficits |  |  | 48 months |  |  |
Alabama Power | Minimum |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |
Maximum period for recovery deferred stock related operations and maintenance costs and any future reserve deficits |  |  | 24 months |  |  |

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