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REGULATORY MATTERS - APC Certificate of Convenience and Necessity and RGC (Details) - Alabama Power $ in Millions | Oct. 24, 2024 USD ($) MW | Jun. 30, 2023 MW | Jun. 14, 2023 MW | Jun. 13, 2023 MW | Apr. 04, 2023 MW
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Schedule of Regulatory Assets and Liabilities [Line Items] |  |  |  |  |
Renewable generation certificate, authorized generating capacity (in MWs) |  | 500 |  |  |
Additional renewable capacity (in MWs) |  |  | 2,400 |  |
Size of allowable projects (in MWs) |  |  | 200 | 80 |
Approval limit (in MWs) |  |  | 400 | 160 |
Renewable generation certificate, generating capacity (in MWs) |  |  |  |  | 498
Tenaska Alabama Partners, L.P. |  |  |  |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |  |  |  |
Consideration transferred | $ | $ 622 |  |  |  |
Approximate nameplate capacity (in MWs) | 855 |  |  |  |

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